esa-sceva/satcom-chunk-collection huggingface dataset:
# Joint Cell Association and User Scheduling in Carrier Aggregated Heterogeneous Networks
## 3 Joint Cell Association Scheme for Multi-Flow Carrier Aggregation
### Iterative Dual Analysis Based Joint Cell Association  
The relaxed problem reformulation (9) has changed the proposed problem (8) from combinatorial optimization into convex optimization. The original problem could be considered as a special case where the users are all associated with only one BS on one carrier band.  
To solve this problem, the Lagrangian Dual Decomposition approach [36] is involved after (9) is rewritten as  
\[\begin{array}{ll}&\underset{\overline{\boldsymbol{\
abla}},\boldsymbol{L}}{ \text{max}}\quad\sum\limits_{n=1}^{N}\sum\limits_{k=1}^{K}\sum\limits_{m=1}^{M }\psi_{k,m  
where \(\mathbf{\Psi}=(\psi_{k,m}^{n})_{k\in\mathcal{K},m\in\mathcal{M}}^{n\in\mathcal{N}}\), and  
\[\begin{array}{ll}&\max\limits_{\mathbf{L}}\quad\sum\limits_{n=1}^{N}\sum\limits_ {k=1}^{K}\lambda_{k}^{n}L_{k}^{n}-\sum\limits_{n=1}^{N}\sum\limits_{k=1}^{K}L_ {k}^{n}log(L_{k}^{n})\\ =&\max\limits_{\mathbf{L}}\quad\sum\limits_{n=1}^{N}\sum\limits_{k=1}^{K}L_{k}^{n} (\lambda_{k}^{n}-log(L_{k}^{n}))\\ &\text{s.t.}\quad\quad L_{k}^{n}=\sum\limits_{m=1}^{M}\psi_{k,m}^{n},\ \ \forall k,n,\\ &\quad\quad 0\leq L_{k}^{n}\leq M,\ \ \forall k,n,\end{array} \tag{14}\]  
where \(\mathbf{L}=(L_{k}^{n})_{k\in\mathcal{K}}^{n\in\mathcal{N}}\).  
This dual formulation has already proved by [PERSON]'s condition [PERSON] (1961) to have a zero dual gap with the primal problem when the optimal resolution of (13) and (14) converges into the same, which means that solving the dual problem (12) offers the original problem (9) with an optimal solution.  
For each \(\lambda_{k}^{n}\), the optimal determination of \(\psi_{k,m}^{n}\) in (13) is to determine which user should be associated with which BS on which carrier which is  
\[f^{*}(m)=\arg\max\limits_{(k,n)}\ (log(C_{k,m}^{n})-\lambda_{k}^{n}),\ \ \forall m. \tag{15}\]  
Apply the well known Karush-Kuhn-Tucker (KKT) method on problem (14) and get  
\[L_{k}^{n}=\left\lceil e^{\lambda_{k}^{n}-1}\right\rceil_{0}^{M}. \tag{16}\]  
To summarize, searching for the maximum sum rate is proceeded by two layers of iterations. The first layer is implemented between the optimal results of (13) and (14). The second layer is the rate adaptation along with the updation of the Lagrangian multipliers. The second layer iteration takes place between the Lagrangian multipliers \(\lambda\) and the converged sum rate achieved from the first layer iteration. The subgradient method is used for the updation of \(\lambda\) as for any \(k\) or \(n\) there is  
\[\lambda_{k}^{n}(Iter+1)=\left\lceil\lambda_{k}^{n}(Iter)-s(Iter)(L_{k}^{n}- \sum\limits_{m=1}^{M}\psi_{k,m}^{n})\right\rceil_{0}^{+}, \tag{17}\]  
where \(Iter\) is the iteration number and \(s\) is the iteration step chosen by the subgradient method [PERSON] (1961).
# Optimal Design and Control of MMC STATCOM for Improving Power Quality Indicators
## 4 Modular Multilevel Converter-Based STATCOM (MMC STATCOM)
### Design of Arm Inductance  
Typically, the inductors used in the arms of the MMC are dry-type air-cored ones. The value of the inductance of the arm can be determined based on the way that the short circuits on the DC-side will be demonstrated. In addition, the inductance of the converter arm plays an important role in enhancing the characteristics of the inter-circulating current and limiting the fault current. Where bypass thyristors are used in the sub-modules or where they are separated using additional diode-based power modules, the AC sharing of the fault current on the DC-side does not need to be restricted to provide protection for the sub-modules' anti-parallel diodes. The arm inductance helps in the limitation of the high frequency harmonics in the inter-circulating current and to provide a smooth control for the circulating current. A typical value of the arm inductance occurs around 0.05 p.u. [24].  
On the other hand, when bypass thyristors are not used in the sub-modules or they are not separated using additional diode-based power modules, protection for the anti-parallel diodes on the DC-side of the converter have to be designed to protect the sub-modules from the high sharing from the AC-side to the fault current in the DC-side. Consequently, as the slow-acting breakers interrupt under this fault current, the arm inductors must restrict the current magnitude to give protection for the anti-parallel diodes, which act as a conduction path for the fault currents. The value of the arm inductance is determined using DC-fault actual time simulation, taking into account the interruption time of the circuit breakers, the time delay until fault detection and the strategy of performing the fault in the control system. Typically, the value of the inductance occurred in a range of 0.10-0.15 p.u.  
Moreover, a short circuit between the terminals of the DC-buses is performed in order to present the most critical fault condition. In order to make a limitation on the short circuit current, the value of the arm inductance should be determined according to [29]:  
\[\mathrm{L_{arm}=V_{dc}/2\alpha} \tag{27}\]  
where \(\alpha\) (kA/s) denotes the maximum rising rate of the current. Based on (27), when the maximum rising rate is = 0.1(kA/\(\upmu\)s) [29], for grid connected converters, the p.u. value of the arm inductance values are restricted at 0.3 pu for Double-Star Chopper Cell (DSCC-MMC), as well as for Single-Delta Bridge Cell (SDBC-MMC) configurations.  
Consequently, modern metaheuristic techniques such as Atom Search Optimization (ASO) and Harris hawk's optimization (HHO) have been proposed in this work for the optimization the of the values of capacitors and the coefficients of the DC voltage regulator of the MMC STATCOM, in order to minimize the total harmonic distortion (THD) in the power system under consideration, keeping the ripple voltage in the allowable ranges and obtaining minimum current circulation within the converter.
_Appl. Sci._**2015**, \(5\), 88-113; doi:10.3390/app5020088  
_applied sciences_  
**ISSN 2076-3417**  
www.mdpi.com/journal/applsci  
_Review_  
**Symmetry-Related Electromagnetic Properties of Resonator-Loaded Transmission Lines and Applications**  
**[PERSON], [PERSON] *, [PERSON] and [PERSON]**  
GEMMA/CIMITEC, Departament d'Enginyeria Electronica, Universitat Autonoma de Barcelona,  
08193 BELLATERRA, Barcelona, Spain; E-Mails: [PERSON]ESS] (J.N.);  
[PERSON].); [PERSON]S] ([PERSON].)  
* Author to whom correspondence should be addressed; E-Mail: [PERSON]DRESS];  
Tel.: +34-93-581-35-22; Fax: +34-93-581-26-00.  
Academic Editor: [PERSON]  
_Received: 12 February 2015 / Accepted: 7 May 2015 / Published: 18 May 2015_  
**Abstract:** This paper reviews the recent progress in the analysis and applications of the symmetry-related electromagnetic properties of transmission lines loaded with symmetric configurations of resonant elements. It will be shown that the transmission characteristics of these reactively loaded lines can be controlled by the relative orientation between the line and the resonant elements. Two main types of loaded lines are considered: (i) resonance-based structures; and (ii) frequency-splitting structures. In resonance-based transmission lines, a line is loaded with a single resonant (and symmetric) element. For a perfectly symmetric structure, the line is transparent if the line and resonator exhibit symmetry planes of different electromagnetic nature (electric or magnetic wall), whereas the line exhibits a notch (resonance) in the transmission coefficient if the symmetry planes behave as either electric or magnetic walls (symmetric configuration), or if symmetry is broken. In frequency-splitting lines, paired resonators are typically loaded to the transmission line; the structure exhibits a single notch for the symmetric configuration, whereas generally two split notches appear when symmetry is disrupted. Applications of these structures include microwave sensors (e.g., contactless sensors of spatial variables), selective mode suppressors (of application in common-mode suppressed differential lines, for instance) and spectral signature barcodes, among others.  
**Keywords:** symmetry properties; transmission lines; microwave sensors; differential sensors; balanced lines; electrically small resonators; metamaterials; common-mode rejection
## 3 Results and Discussion  
### Isolation and Identification of F19  
In our preliminary screening work, nine strains were isolated, and their nitrogen removal capabilities under aerobic conditions were examined. A strain exhibiting more than 90% ammonium and TN removal efficiency within 24 h without nitrite accumulation was identified and named F19. Strain F19 also exhibited the highest ammonium removal efficiency under a low C/N ratio (<4:1). A fragment of 16S rDNA \(\sim\)1400 bp in length was obtained by PCR, sequenced, and submitted to the GenBank database under accession number MH628667. BLAST homology searches against GenBank indicated that the novel strain F19 was most closely related to _J. svalbardensis_ (100% similarity). To determine the genus relationship, a neighbor-joining phylogenetic tree was subsequently constructed based on the 16S rRNA gene sequence of the isolate and those of phylogenetically related strains and other strains with nitrogen removal capability (Figure 1). The results suggested that strain F19 was a member of the genus _Janthinobacterium_.
# Ice Thickness Detection of Transmission Lines Based on Cross-Guide-UNet
## 3 Cross-Guide-UNet (CG-UNet)  
The CG-UNet edge detection model, illustrated in Figure 1, follows an encoder and decoder framework. In this model, the image of ice-covered power lines is input into the encoder to extract image features at various levels.  
\begin{table}
\begin{tabular}{c c c} \hline
**Classification** & **Algorithm** & **Advantages and Disadvantages** \\ \hline \multirow{6}{*}{Traditional edge detection algorithms} & \multirow{2}{*}{Canny} & It can recognize simple edge information, but the overall detection accuracy is not high. \\ \cline{2-3}  & & Ratio & Capable of detecting multi-scale and multi-directional edge information, sensitive to noise. \\ \cline{2-3}  & \multirow{2}{*}{Improvement Canny} & Improved the detection accuracy of the Canny operator, but the calculation process is more complex. \\ \cline{2-3}  & & LSD & The LSD algorithm is used for linear detection, but it performs poorly in complex backgrounds. \\ \hline \multirow{6}{*}{Deep learning algorithms} & \multirow{2}{*}{S\_UNet} & The use of IBP algorithm to determine the parameters of convolutional layers is a complex training process and difficult to optimize parameters. \\ \cline{2-3}  & & The use of transfer learning and attention mechanisms for ice-covered area segmentation is not precise enough for edge detail processing. \\ \cline{2-3}  & \multirow{2}{*}{Mask RCNN} & The use of object detection technology for ice thickness recognition can only determine whether the ice thickness is within a certain range. \\ \cline{1-1} \cline{2-3}  & & The use of object detection technology for ice thickness recognition can only determine whether the ice thickness is within a certain range. \\ \hline \end{tabular}
\end{table}
Table 1: Comparison of edge detection algorithms for ice-covered transmission lines.  
In CG-UNet, the encoder extracts different levels of features from the image through multi-layer convolution operations, including basic features such as color, texture, and shape. For example, in early convolutional layers, low-level features such as the edges and lines of the image are mainly extracted, which help the model to preliminarily identify the contours of transmission lines and ice; as the convolutional layer deepens, more advanced and abstract features are gradually extracted, such as the spatial relationship between the ice and transmission lines, providing rich information for subsequent ice edge detection and thickness calculation.  
We implemented a CGM during decoding to facilitate interaction between information from different features. The features extracted by the encoder and decoder traverse the CGM, where calculated attention weights are derived. These weights are subsequently cross-multiplied with the input features to achieve deep-level feature fusion. Ultimately, the edge detection image is generated through multiple sampling modules.
_Applied_  
_sciences_  
Application of Semiconductor Optical Amplifier (SOA) in Managing Chirp of Optical Code Division Multiple Access (OCDMA) Code Carriers in Temperature Affected Fibre Link  
[PERSON] *\({}^{\copyright}\) and [PERSON]\({}^{\copyright}\)  
Department of Electronic and Electrical Engineering, University of Strathclyde, Glasgow G1 1 XW, UK,  
[EMAIL_ADDRESS]  
\({}^{\copyright}\) Correspondence: [EMAIL_ADDRESS]; Tel.: +44-745-901-1635  
Received: 27 March 2018; Accepted: 30 April 2018; Published: 3 May 2018  
Featured Application: The application of a semiconductor optical amplifier (SOA) in an incoherent Optical Code Division Multiple Access (OCDMA) system based on multi-wavelength picosecond code carriers is explored for mitigation of temporal distortion of an OCDMA auto-correlation affected by the temperature induced dispersion changes in a fibre optic transmission link.  
Chromatic and temperature induced dispersion can both severely affect incoherent high data rate communications in optical fibre. This is certainly also true for incoherent optical code division multiple access (OCDMA) systems with multi-wavelength picosecond code carriers. Here, even a relatively small deviation from a fully dispersion compensated transmission link can strongly impact the overall system performance, the number of simultaneous users, and the system cardinality due to the recovered OCDMA auto-correlation being strongly distorted, time-skewed, and having its full width at half maximum (FWHM) value changed. It is therefore imperative to have a simple tunable means for controlling fibre chromatic or temperature induced dispersion with high sub-picosecond accuracy. To help address this issue, we have investigated experimentally and by simulations the use of a semiconductor optical amplifier (SOA) for its ability to control the chirp of the passing optical signal (OCDMA codes) and to exploit the SOA ability for dispersion management of a fibre link in an incoherent OCDMA system. Our investigation is done using a 19.5 km long fibre transmission link that is exposed to different temperatures (20 \({}^{\circ}\)C and 50 \({}^{\circ}\)C) using an environmental chamber. By placing the SOA on a transmission site and using it to manipulate the code carrier's chirp via SOA bias adjustments, we have shown that this approach can successfully control the overall fibre link dispersion, and it can also mitigate the impact on the received OCDMA auto-correlation and its FWHM. The experimental data obtained are in a very good agreement with our simulation results.  
group velocity dispersion; chirp; optical code division multiple access auto-correlation; fibre propagation; chromatic dispersion; temperature induced dispersion; super-continuum generation; optical code division multiple access transmitter; optical code division multiple access receiver/decoder; semiconductor optical amplifier
# The Development and Analysis of a Multistage Spraying Method for Liquids in an Ultrasonic Field
## 4 Results and discussion
### Dependence on Liquid Surface Tension  
It is known that surface tension is the key factor affecting the wavelength of generated Faraday capillary waves and, consequently, the diameter of generated liquid droplets [16]. A solution of ethyl alcohol in water in proportions of 20%, 30%, 40%, 60%, and 80% was used as the spray liquid. The respective surface tensions of the solutions were equal: 40.9 mN/m, 36 mN/m, 32.1 mN/m, 28.8 mN/m, and 25.6 mN/m [36]. The sound pressure level was 182 dB, and the liquid flow rate was 5 mL/s. Figure 14 shows comparative histograms of droplet distribution formed at minimum and maximum ethyl alcohol content in solution.  
It follows from the presented histograms that a decrease in the surface tension (higher alcohol content in the solution) contributed to a decrease in the diameter of the formed droplets. This was caused by a decrease in the wavelength of the generated Faraday  
Figure 12: Histograms of liquid droplet diameter distribution at different liquid viscosities: (a) 1.8 mPa-s; (b) 10.8 mPa-s.  
Figure 13: Dependence of median droplet diameter on liquid viscosity. Error bars indicate standard deviation. Experimental data fit polynomial regression (\(n=2\)).  
capillary waves (see Equation (1)). In addition, the spread of the formed droplets' diameters also decreased. The histogram in Figure 13(b) becomes narrower.  
Figure 15 shows the dependence of the median diameter of the formed droplets on the surface tension of the liquid. Each experimental point in Figure 15 was obtained by averaging 10 Sauter diameter measurements (determined using Malvern SprayTech). The experimental data correspond to polynomial regression. The error bars indicate standard deviation.  
Figure 15 shows that the median diameter of the formed droplets monotonically decreased with the decreasing surface tension of the liquid. However, the dependence (a decrease by 8 \(\upmu\)m) of the median droplet size on the surface tension was not as significant as that on the sound pressure level.  
Thus, a multistage spraying technique, consisting of the generation of a large number of large-initial-diameter particles (to ensure high productivity) and their subsequent breakdown during propagation in an ultrasonic field, was proposed. The disperse characteristics of the formed droplets, from the modes of ultrasonic exposure and the properties of the liquid, were studied. It was shown that the method of multistage spraying of a liquid enables the generation of liquid droplets of smaller diameters and with higher productivity than other commonly used techniques of ultrasonic spraying (spraying in a layer and spraying in a fountain).  
Figure 14: Histograms of liquid droplet diameter distribution at different liquid surface tensions: (a) surface tension of 40.9 mN/m; (b) surface tension of 25.6 mN/m.  
Figure 15: Dependence of median droplet diameter on liquid surface tension. Error bars indicate standard deviation. Experimental data fit polynomial regression (\(n=2\)).
## 3 Results and Discussion
### Effect of Particle-Box Interaction  
As discussed, the gradual increase in shear stress following the curve inflection point was observed both in Type 3a and Type 3b and its main cause was still not clear. This phenomenon was further studied and elaborated upon. In this regard, two more displacement transducers attached to front and rear of the shear box were introduced for assessing particle movement while shearing in LSDS mode. Figure 12 shows the vertical displacement at front and rear of the shear box versus the RHD for the loess-PHW mixture specimen at \(\omega=18\%\) and \(22\%\), respectively, as subjected to the normal pressures of 100, 200 and 300 kPa. The vertical upwards displacement at front of the shear box was at most 5.3 mm, while the vertical downwards displacement at rear was typically 6-12 mm. The magnitude of the vertical displacements was more distinct at the rear of the shear box than at the front. Additionally, the greater the normal pressure applied, the larger the vertical displacement. The above results indicate that the particles, during shearing, tended to move to front and rear of the shear box and that the greater normal pressure largely promoted the movement of particles. The observed movement of particles was deemed as the main cause to lead to the further gradual increase in the shear stress observed both in Type 3a and Type 3b.  
Figure 11: Variation of loess height, unit weight and friction angle from LSDS at %PHW of 0.45, 0.6, 0.75 and 1.0: (**a**) specimen at \(\omega=14\%\), (**b**) specimen at \(\omega=18\%\) and (**c**) specimen at \(\omega=22\%\).  
Figure 12: Vertical displacement at front and rear of the shear box versus relative horizontal displacement (RHD) considering three normal pressures of 100, 200 and 300 kPa: (**a**) specimen at \(\omega=18\%\) and (**b**) specimen at \(\omega=22\%\).
# Nonlinear Dynamics of a Resonant-Impact Dielectric Elastomer Actuator
## 3 Numerical and Experimental Study Results
### Effects of Number of DEA Layers  
To improve the output performance, multiple layers of DEAs can be stacked together to actuate in parallel, which enhances the power/work outputs. This subsection investigates the effects of the number of DEA layers on the frequency responses of the resonant-impact DEA system. First, through a non-dimensional numerical study, the layer number of the resonant-impact DEA system is varied from 1 to 8 with the other parameters remaining unchanged; the frequency response results are shown in Figure 9a. It can be noted that increasing the layer number leads to a higher peak frequency \(\omega_{e}\), although it shows negligible influence on the peak oscillation amplitude. Figure 9b shows that the peak impact force \(\mid\)_f\({}_{max}\)\(\mid\)_ increases with the number of layers, which is as expected due to the multiplied power/work outputs. The \(\mid\)_f\({}_{max}\)\(\mid\)_ for the 8-layer case is more than twice that for the single-layer case.  
The experimental and corresponding modelling results on the effects of the number of layers are shown in Figure 10, where 1, 2, and 3 layers of resonant-impact DEA systems were investigated. It can be noted from Figure 10 that while more layers of DEAs results in a higher peak frequency \(\Omega_{p}\) and peak impact force \(\mid\)_F\({}_{max}\)\(\mid\)_, there is a negligible effect on the peak amplitude \(\mid\)_Amp._\(\mid\); hence, the results successfully verify the findings reported in the nondimensional numerical study in Figure 9.  
Figure 8: Experimental and modelling results on the effects of excitation voltage amplitude on (**a**) peak frequency and oscillation amplitude and (**b**) peak impact force. The discrete markers represent the experimental data and the continuous curves are the modelling results.  
Figure 9: Effects of the number of DEA layers on (**a**) the frequency responses and (**b**) the peak frequency and peak impact force of the resonant-impact DEA system.