esa-sceva/satcom-chunk-collection huggingface dataset:
###### Abstract  
This paper presents a detailed analysis of commutation failure, AC/DC power flow, and voltage stability of multi-infeed high-voltage direct current (HVDC). The use of HVDC power transmission technology has become common in modern power systems. During the past two decades, HVDC technology has been extensively used for long-distance bulk power transmission to remote areas. Throughout the world, the demand for power has drastically increased in recent years due to industrialization; such situations make HVDC an economic candidate because the distance between power generation plants and load areas is significantly very long. The line-commutated converter (LCC) technology-based HVDC system is well more mature than other available conversion schemes (i.e., voltage source converters), and it is widely used in high-power projects. China had approximately 50 HVDC-LCC links in 2020, and a single LCC-based link with the highest capacity is 12 GW. The installation of several HVDC links in an existing power network has led to a situation where two or more HVDC links terminate in the electric vicinity of each other's AC network or even in same AC busbar. Such scenarios are termed multi-infeed HVDC system. Multi-infeed HVDC systems bring various challenges related to voltage stability, local and concurrent commutation failure, and AC/DC power flow. Here, the literature available on these phenomena of LCC-based HVDC is discussed for future research. The assumptions and drawbacks of various techniques used for investigating the mentioned phenomena are also highlighted.  
l pacs: 17 September 2021
## 3 Results
### Quantitative Results  
The image classification networks and object detection networks were trained using four prepared datasets for comparison, including the data augmentation method proposed in this study. The types of datasets are as follows: (1) original dataset, (2) one-channel dataset with the original dataset, (3) three-channel grayscale dataset with the original dataset, and (4) three-channel color dataset with the original dataset.  
During the evaluation process, the trained network was validated (1) using the original validation data with the augmented validation data and (2) only using the original validation data.  
The networks were trained ten times for each experimental condition to verify the reproducibility and repeatability of each metric. Subsequently, we showed average, standard deviation, and boxplot for each metric.
## 5 Conclusions  
In this paper, we proposed an improved and efficient local alternative search algorithm for phase retrieval named GARLM. Specifically, the proposed GARLM algorithm is a local search iterative algorithm to recover the sparse signal from its Fourier transform magnitude. The proposed algorithm is preferred to existing greedy methods of phase retrieval. The problem of phase retrieval is a non-convex problem of minimizing the sum of squared errors with support information. To recover the unknown signal, we first transformed this non-convex problem to a linear least squares problem, and then invoked ILM and 2-opt algorithms to recover the original signal. Simulation results have confirmed that compared to the classic greedy algorithm GESPAR for phase retrieval, our algorithm performs well in terms of recovery probability, robustness to noise, and effectiveness. The proposed algorithm GARLM has also proved to be effective in solving phase retrieval problems and performs well in terms of noise robustness via simulations.  
Conceptualization, Z.X. and D.Z.; methodology, Z.X.; software, K.Z.; validation, Y.Z. and G.G.; writing-original draft preparation, Z.X.; writing-review and editing, Z.X. and G.G.; supervision, Y.Z.; project administration, Z.X.  
This research was funded by the National Natural Science Foundation of China (61571240), Jiangsu, Specially-Appointed Professor Grant (RK002 STP16001), Innovation and Entrepreneurship of Jiangsu High-Level Talent Grant (CZ0010617002), the Horizontal Foundation of Fuyang Normal University (XDHX201741), Anhui Provincial Major Projects of Scientific Research of Universities (KJ2018 ZD036), Anhui Provincial Department of Education Natural Science Research Project (KJ2018A0336) and 1311 Talent Plan of Nanjing University of Posts and Telecommunications.  
The authors declare no conflict of interest.
# Secure D2D Communication for 5G IoT Network Based on Lightweight Cryptography
## 2 Related Work  
### Typical Security Threats of D2D Communication  
D2D communication involves three steps, device discovery, link setup and data transmission, to make a direct connection between devices. In the device discovery step, the device searches for nearby devices. Then devices that are discovered in the previous step make a connection for transmitting data in the link setup step. After a connection is established, the data is transmitted through a direct link in the data transmission step. However, if there are no proper security measures, the data can be vulnerable to some security threats by attackers. Typical security threats of D2D communication introduced in [5] are as follows:  
* Impersonation attack. In this attack the attacker acts like a legitimate user by using an identity such as an international mobile subscriber identity (IMSI). To prevent this attack proper authentication of users has to be considered.
* Eavesdropping. This is a type of attack where the attacker passively listens to communication between users and thereby the attacker can capture the transmitted data and also can fabricate the data. To prevent this attack, data confidentiality and integrity have to be considered.
* Privacy sniffing. D2D communication has to broadcast request messages to search for nearby devices. However, the attacker uses this feature to find and track the victim device. To mitigate this security threat, the devices have to use an anonymous identity, and it has to be authenticated.
* Free riding attack. Selfish devices receive the desired data from other devices but do not share their resources because of energy consumption and because of this they reduce system availability. To mitigate this attack, the user identity has to be authenticated and managed by a base station.
* Location spoofing. In this attack a malicious device may broadcast a request message with wrong or artificial location information to disrupt D2D communication in the device discovery step. To mitigate this attack, the request message has to be processed only from validated devices in D2D communication.
# Gaussian Dynamic Convolution for Semantic Segmentation in Remote Sensing Images
## 4 Experiments
### Dataset and Metric  
The iSAID is a large dataset for the high-resolution remote sensing image segmentation task. Its original images are derived from the large-scale aerial dataset DOTA, which is captured by aircraft, UAVs, and satellites from different platforms. The dataset contains 2806 images and 655,451 object instances in 15 categories. The categories are defined as: storage tank (ST), baseball diamond (BD), tennis court (TC), basketball court (BC), ground field track (GTF), large vehicle (LV), small vehicle (SV), helicopter (HC), swimming pool (SP), roundabout (RA), soccer ball field (SBF). Since the work in this paper involves only semantic segmentation, only the semantic mask annotations of this dataset are used.  
The LoveDA was released by the team from Wuhan University and contains 5987 high-resolution images of remote sensing from the cities of Nanjing, Changzhou, and Wuhan. The dataset is divided into two parts: urban and rural, and contains seven categories.  
We adopt mean intersection over union (mIoU), commonly used in semantic segmentation, as the main evaluation metric to demonstrate the performance of our method.
# An Efficient Library for Reliability Block Diagram Evaluation
## 2 Reliability Block Diagrams
### Reliability Evaluation Using RBD  
The same mathematics described in Section 2.2 can be used to analytically compute the reliability curve of a block given the reliability curves of its components. In order to perform this time-dependent analysis, it is sufficient to replace each occurrence of \(p_{x}\) and \(q_{x}\) in equations from Equation (2) to Equation (12) with, respectively, \(R_{x}(t)\) and \(F_{x}(t)\).  
The statement above is trivial and it is justified as follows: recall the probabilistic definition of reliability, i.e., the probability that the state of a given system or component at a given time \(t\) is equal to _success_ given that it was correctly operating at the initial time \(t_{0}\). We can then apply the same mathematics in Section 2.2 to quantitatively evaluate the probability that the state of an RBD block is equal to _success_ at time \(t\), i.e., its reliability.  
The described approach can be easily adapted to those applications for which the analytical reliability curve is not needed but only samples acquired from it are sufficient. For example, the reliability curve of a system can be sampled at time instants \(t_{0}+k\cdot\Delta t\), where \(t_{0}\) is the initial time, \(k\in\mathbb{N}\) and \(\Delta t\) is the sampling period, by sampling the reliability curves of its components and by applying the proper equations for each evaluated time instant.
## 2 Power Quality in DC Microgrids
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Problem** & **Common Causes** & **Common Effects** & **AC** & **DC** \\ \hline Voltage & Variable load, & Light flicker, & Yes & No \\ Fluctuations & compensator failures & equipment malfunction & & \\ \hline Voltage Sags & Motor starting, & Shutdown of & Yes & Yes \\  & short circuits & sensitive equipment & & \\ \hline Voltage Swells & Lightning strikes, & Damage to electronic & Yes & Yes \\  & grid switching & devices and insulation & & \\ \hline Electrical Noise & Electromagnetic & Corrupted data, & Yes & Yes \\  & interference (EMI), & instability in sensitive & & \\  & industrial sources, & circuits, audible noise, & & \\  & poor shielding, & communication errors & & \\  & switching devices & & & \\ \hline Frequency & Overloaded grid, & Degraded motor and & Yes & No \\ Fluctuations & intermittent generation & relay performance & & \\ \hline Transient & Lightning strikes, & Damage to insulation & Yes & Yes \\ Voltages & load switching & and electronic circuits & & \\ \hline Unbalance & Unequal phase & Neutral overheating, & Yes & No \\  & distribution & motors low efficiency & & (unipolar) \\  & or fault & & & \\ \hline Harmonics & Power Electronics, & Overheating, & & \\  & nonlinear loads, & equipment malfunction & & \\  & PWM inverters & & & \\ \hline Ripple & Poorly regulated power & Component overheating, & No & Yes \\  & supplies, rectifier & audible motor noise, & & \\  & design issues, & reduced lifespan & & \\  & inadequate filtering & of components & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summary of power quality problems, their common causes, effects, and relevance to AC and DC systems. employed in electrical systems. Establishing a common voltage level would be beneficial, as even though certain devices can handle wide-range input voltages, system dynamics and behavior remain significantly affected. For example, the classification of voltage dips differs across systems. In terms of power quality, there is no clear consensus on which types of voltage events, such as dips and swells, are acceptable. The same challenge applies to voltage ripple. Key Performance Indicators (KPIs) need to be defined for phenomena like distortion, similar to how Total Harmonic Distortion (THD) is used for AC grids. Additionally, for Electromagnetic Compatibility (EMC) concerns, such as switching frequencies, standardized limit values have not yet been established.
## 4 Analysis and Discussion
### Analysis of Cross-Attentions
#### 4.3.2 Cross-Attention between the Different Languages  
This analysis is designed to observe how the cross-attentions are calculated when a source and a target language are quite different. This analysis is illustrated in Figure 5. The results are presented in Table 7 and Figure 6.  
(1) We can assert that the respective word orders of Korean and Japanese are almost the same. In the attention \(AttnI_{\rightarrow K}^{K}\) of the Japanese-Korean model, the number of tokens aligned in the reverse order is still below 1%, while that of the English-Korean model soars to 17.256%.  
(2) The number of non-aligned and aligned tokens in the reverse order in \(Attn_{E\rightarrow K}^{EK}\) goes up to 41.279%, while that in \(AttnI_{\rightarrow K}^{K}\) still remains at 14.651%.  
From the analyses of cross-attentions between the languages, we can conclude that Japanese and Korean are very similar in terms of machine translation. The word orders of the two languages are very similar, and thus the alignment between the two languages monotonically increases, excepting about 1%, and below 15% when considering non-aligned tokens. Conversely, about 41% of the alignments of cross-attentions between English and Korean are reversed in word order, or has meaningless attentions.
## 2 Materials and Methods
### Model Parameter Obtaining Process
#### 2.2.2 The Genetic Algorithm  
To minimize the described function (MSE of the power spectrum), the Global Optimization Toolbox of the Matlab environment was utilized [28].  
To ensure robustness and avoid possible local minima problems, the algorithm was conducted with the population size of 256. The parameter obtaining process stopped after 150 populations, when the performance stagnated. Selection of parents for the consecutive generations was conducted using the stochastic universal sampling. In the reproduction step, 13 (5% of the population size) best individuals were guaranteed to survive to the next generation. The remaining 243 individuals were obtained in 80% by crossover and in 20% by Gaussian mutation.  
The algorithm sought the function values in the ranges presented in Table 2, among real numbers.  
\begin{table}
\begin{tabular}{c c c} \hline
**Parameter** & **Lower Search Range** & **Upper Search Range** \\ \hline \(A\) (mV) & 2.25 & 4.25 \\ \(B\) (mV) & 12 & 32 \\ C & 70 & 675 \\ \(v0\) (mV) & 5 & 7 \\ \(e0\) (s\({}^{-1}\)) & 2 & 3 \\ r & 0.5 & 0.6 \\ Lower noise limit (pps) & 50 & 300 \\ Noise range (pps) & 200 & 1000 \\ \hline \end{tabular}
\end{table}
Table 2: Ranges of the search domains of particular parameters.  
Figure 3: Visualization of the function minimized in this study. Plots (**a**–**c**) show spectra of the signals: original, modeled, and their difference, respectively. Note, that plot (**c**) is an absolute value of the difference.
# Promoting Urban Farming for Creating Sustainable Cities in Nepal
## 4 Food and Human Health
In a highly dense city like those in the Kathmandu Valley, shallow-rooted vegetables are grown on rooftops, on balconies, in facades, indoors, in windows [36; 37] of abandoned buildings, and in interstitial spaces between legal lands. Taller buildings obstruct the solar radiation, thus hindering the process of photosynthesis [38]. These built-in infrastructures offer very little room to produce vegetables and fruit; often, crops are grown on vertical structures [39]. These spaces do not have the provisions required to grow deep-rooted plants. In vertical structures, often light becomes insufficient. To supplement this solar radiation, LED light is used. In such narrow spaces, using animal dung to grow crops emits methane gas; however, using compost helps in sequestering greenhouse gases. Light Emitting Diode (LED)-produced light can be used to sustain light intensity in a controlled environment. This will help create more efficient growth and a much higher yield per growing area. Several crops with adventitious roots can be grown in biodegradable pots such as those made from coconut husk. For example, mushrooms, lettuce, kale, cauliflower, broccoli, pepper, and zucchini can be grown in such pots. In addition to these crops, other tubers and legumes can be cultivated on an urban rooftop in a horizontal manner. However, in peri-urban farms, they could be grown in a horizontal manner directly on the ground soil in the open spaces on building sites. It is estimated that gray area farming may contribute to 5 and 10% of the global production, while also ameliorating global climate change [40, 41]. If urban and peri-urban areas are efficiently utilized to produce agricultural crops, the food produced there can be enough to feed approximately 30% of the total urban population in different geographic regions of the world [42]. Coffee and tea wastes, along with the barks peeled from cucumbers and potatoes and the stems and leaves from the salad can be used to grow such agricultural crops. Though such crops require water, the quantity of water used is 70% less than in the traditional farms for the same amount of harvest. Urban farming helps in cooling the urban areas by using less water and less space and mitigating the heat radiated by built-up hard surfaces [36]. Ambient cooling happens in two ways. First, soil moisture cools the nearby environment, and second, evapotranspiration and oxygen generated from plants also contribute to the cooling of the environment. Thus, urban farming can contribute to accomplishing twin goals, increase in local food production and environmental cooling. Most importantly, urban farming will help to reduce the mounting food waste.
# Bamboo Garden Trimming Problem: Priority Schedulings +
###### Abstract  
The paper deals with the _Bamboo Garden Trimming_ (BGT) problem introduced in [[PERSON] et al., SOFSEM'17]. The problem is difficult to solved due to its close relationship to _Pintwheel scheduling_. The garden with \(n\) bamboos is an analogue of a system of \(n\) machines that have to be attended (e.g., serviced) with different frequencies. During each day, bamboo \(b_{i}\) grows an extra height \(h_{i}\), for \(i=1,\ldots,n\) and, on the conclusion of the day, at most one bamboo has its entire height cut.The goal is to design a perpetual schedule of cuts to keep the height of the tallest ever bamboo as low as possible. The contribution in this paper is twofold, and is both theoretical and experimental. In particular, the focus is on understanding what has been called _priority schedulings_, i.e., cutting strategies where priority is given to bamboos whose current height is above a threshold greater than or equal to \(H=\sum_{i=1}^{n}h_{i}\). Value \(H\) represents the total daily growth of the system and it is known that one cannot keep bamboos in the garden below this threshold indefinitely. As the first result, it is proved that, for any distribution of integer growth rates \(h_{1},\ldots,h_{n}\) and any priority scheduling, the system stabilises in a fixed cycle of cuts. Then, the focus is on the so-called ReduceMax strategy, a greedy priority scheduling that each day cuts the tallest bamboo, regardless of the growth rates distribution. ReduceMax is known to provide a \(O(\log n)\)-approximation, with respect to the lower bound \(H\). One of the main results achieved is that, if ReduceMax stabilises in a round-robin type cycle, then it guarantees 2-approximation. Furthermore, preliminary results are provided relating the structure of the input instance, in terms of growth rates, and the behavior of ReduceMax when applied to such inputs. Finally, a conjecture that ReduceMax is 2-approximating for the BGT problem is claimed, hence an extended experimental evaluation was conducted to support the conjecture and to compare ReduceMax with other relevant scheduling algorithms. The obtained results show that ReduceMax: (i) provides 2-approximation in all considered inputs; and (ii) always outperforms other considered strategies, even those for which better worst case approximation guarantees have been proven.  
Keywords:bamboo garden trimming; periodic scheduling; approximation algorithms; perpetual testing; experimental evaluation +
Footnote †: 2019, 12, 74; doi:10.3390/a12040074
## 4 Experiment
### Comparison of Experimental and Simulation Results  
The results of Simulation #1 and Experiment #1 were compared. The physical fidelity of the simulation model, including the simulator and control policy, was validated.  
Figure 20 shows the sensor signals obtained by the simulation and experiment. The NMSEs between the experimental and simulation signals from the No. 1 to No. 4 sensors are 14%, 17%, 15% and 19%, respectively. Figure 21 shows the actuator signals obtained  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Uncontrolled (V2/Hz)** & **Controlled (V2/Hz)** & **Reduction (\%)** \\ \hline \multirow{3}{*}{No. 1 Sensor} & @53 Hz & 0.0099 & 0.0007 & 92.65\% \\  & @56 Hz & 0.0121 & 0.0012 & 90.39\% \\  & @59 Hz & 0.0138 & 0.0029 & 79.31\% \\ \hline \multirow{3}{*}{No. 2 Sensor} & @53 Hz & 0.0061 & 0.0017 & 72.52\% \\  & @56 Hz & 0.0092 & 0.0017 & 81.76\% \\  & @59 Hz & 0.0122 & 0.0041 & 66.49\% \\ \hline \multirow{3}{*}{No. 3 Sensor} & @53 Hz & 00032 & 0.00008 & 97.55\% \\  & @56 Hz & 0.0027 & 0.0001 & 95.78\% \\  & @59 Hz & 0.0021 & 0.0002 & 90.00\% \\ \hline \multirow{3}{*}{No. 4 Sensor} & @53 Hz & 0.0129 & 0.0049 & 61.80\% \\  & @56 Hz & 0.0191 & 0.0049 & 74.47\% \\ \cline{1-1}  & @59 Hz & 0.0244 & 0.0116 & 52.53\% \\ \hline \hline \end{tabular}
\end{table}
Table 8: Peak values of PSD curves of sensor signals: Experiment #3.  
Figure 19: PSDs of sensor signals obtained by experiments.  
by the simulation and experiment. The NMSEs between the experimental and simulation signals from the No. 1 to No. 4 actuators are 17%, 11%, 13% and 15%, respectively.  
Figure 21: Comparison of actuator signals in time domain. Comparison of Experiment #1 and Simulation #1.  
Figure 20: Comparison of sensor signals in time domain. Comparison of Experiment #1 and Simulation #1.  
The errors mainly come from the errors between the real-world vibration system and the simulator, the time delay and signal interference of the electronic components, external disturbances, and so on. However, the errors can be accepted. On the one hand, the errors are smaller than 20%, which can be accepted in most engineering problems. On the other hand, the experiment results also show that the simulation model has enough physical fidelity, and the proposed method for designing the vibration controller is effective and useful.