esa-sceva/satcom-chunk-collection huggingface dataset:
## 3 Case Studies
### DCMG Model Control  
As far as the model's mode of operation is concerned, it must be based on bidirectional energy flow, so that the DCMG and the AC distribution network can support each other. When the BESS no longer has storage capacity, to avoid losses, this energy can be injected into the AC distribution network. Thus, there are two main operating modes, the island mode, where the DCMG operates in island mode, i.e., where its operation is maintained by the RES and the BESS, and the AC distribution network is disconnected, and the mode connected to the AC distribution network, in case it is necessary to extract the excess energy produced in the DCMG or also to supply energy to it if necessary.  
The model simulated in MATLAB/Simulink was based on a two-level hierarchical control, i.e., with a lower control level and an upper control level. At the lower level, control is decentralized, which means that each component of the DCMG, such as the RES, power converters and BESS have local controllers. These controllers adjust operating parameters such as voltage, current and power autonomously and in real time in order to maintain the stable and efficient operation of each device. Decentralization provides a rapid response to local events, such as changes in energy production (for example, variation in solar irradiation) or fluctuations in load demand, without relying on communication or coordination with a central controller. This results in greater robustness, as failures in one subsystem do not directly affect the control of the others.  
The upper level, on the other hand, acts centrally and takes on a global coordination and optimization role. A central controller monitors the behavior of the entire DCMG, and receives information from the local controllers. Based on this data, the central controller makes strategic and long-term decisions, such as managing the flow of energy between renewable sources and storage, integrating priority loads, or choosing the most appropriate  
Figure 11: Average wind speed for a February day in Real, Amarante.  
Figure 10: Average Solar Irradiation for a February day in Real, Amarante.  
time to store or export energy. This level also guarantees the stability and optimization of the system in terms of energy efficiency and operating costs, resources are managed more efficiently and it is ensured that the DCMG operates sustainably.  
The combination of these two levels allows the DCMG autonomy and flexibility at the local (decentralized) level, while maintaining global coordination to achieve overall objectives such as stability, economy and efficient resource management. In this way, the ability to respond immediately and the holistic vision of the system are balanced, thus optimizing the overall performance of the DCMG.
# Improved Subsidence Assessment for More Reliable Excavation Activity in Tehran
###### Abstract  
This paper presents a particular tunneling method, the new Austrian tunneling method (NATM), which plays an important role in reducing subsidence of the surface and damage to structures in urban areas. It has a wide range of applications in shallow tunneling projects all over the world. In this study, numerical modeling of the third-line Metro tunnel in Tehran, which is designed and stabilized by the NATM, is under discussion. The foregoing tunnel is excavated manually with a one-meter advancing step. In this project, the constructors use a lattice girder and spray concrete with 31 cm thickness as the initial lining. A suitable numerical software for this modeling is PLAXIS 3D Tunnel, which allows high-resolution finite element modeling (FEM) of the studied object. The performance of this method is investigated and compared with that of other NATMs. The numerical modeling yielded a value of 30.01 mm for earth subsidence in the most damaged area of the settlement, which was confirmed with a dramatically low difference by earth surface monitoring. Moreover, this tunnel was drilled and excavated using various methods, among which the least settlement was obtained by the proposed method. The results are promising, and they indicate that tunneling with this method should continue to be used to expand the subway line in the city.  
NATM; tunnel; FEM; earth surface subsidence; subsidence monitoring Article
###### Abstract  
Synthetic aperture radar (SAR) is more sensitive to the dielectric properties and structure of the targets and less affected by weather conditions than optical sensors, making it more capable of detecting changes induced by management practices in agricultural fields. In this study, the capability of C-band SAR data for detecting crop seeding and harvest events was explored. The study was conducted for the 2019 growing season in Temiskaming Shores, an agricultural area in Northern Ontario, Canada. Time-series SAR data acquired by Sentinel-1 constellation with the interferometric wide (IW) mode with dual polarizations in VV (vertical transmit and vertical receive) and VH (vertical transmit and horizontal receive) were obtained. interferometric SAR (InSAR) processing was conducted to derive coherence between each pair of SAR images acquired consecutively in time throughout the year. Crop seeding and harvest dates were determined by analyzing the time-series InSAR coherence and SAR backscattering. Variation of SAR backscattering coefficients, particularly the VH polarization, revealed seasonal crop growth patterns. The change in InSAR coherence can be linked to change of surface structure induced by seeding or harvest operations. Using a set of physically based rules, a simple algorithm was developed to determine crop seeding and harvest dates, with an accuracy of 85% (n = 67) for seeding-date identification and 56% (n = 77) for harvest-date identification. The extra challenge in harvest detection could be attributed to the impacts of weather conditions, such as rain and its effects on soil moisture and crop dielectric properties during the harvest season. Other factors such as post-harvest residue removal and field ploughing could also complicate the identification of harvest event. Overall, given its mechanism to acquire images with InSAR capability at 12-day revisiting cycle with a single satellite for most part of the Earth, the Sentinel-1 constellation provides a great data source for detecting crop field management activities through coherent or incoherent change detection techniques. It is anticipated that this method could perform even better at a shorter six-day revisiting cycle with both satellites for Sentinel-1. With the successful launch (2019) of the Canadian RADARSAT Constellation Mission (RCM) with its tri-satellite system and four polarizations, we are likely to see improved system reliability and monitoring efficiency.  
SAR; interferometry; Sentinel-1; harvest; seeding; change detection Article
## 3 Results and Discussions
### Simulation
#### 3.1.2 Simulation Results  
Taking the spill scenario with a river flow of 5000 m\({}^{3}\)/s, a south-west wind of 2.1 m/s, and a rupture spill (spill volume of 2600 t, spill time of 0.5 h) as an example, Figure 5 shows the state of oil spill transport at each time point. After the crude oil was spilled into the river, the oil spill continued to migrate downstream along the north bank of the river under the action of the water current and the southwest wind. In the early stage of the spill at t = 1 h, the oil film is more aggregated, the area and length of the oil spill contamination zone are **A** = 8.19 \(\times\) 10\({}^{4}\) km\({}^{2}\) and **L** = 3.37 km, respectively, and the average thickness of the oil film is **T** = 1.07 mm. In the migration process, the oil spill will diffuse and extend  
Figure 4: Rose wind map of the basin.  
continuously along the river channel under the hydrodynamic force of the river, the pulling force of the wind, and the obstructing force of the river bank. When \(t=5\,h\), the oil spill head migrates to the tail of the simulated river section; at this time, the area and length of the oil spill pollution zone are \(\mathbf{A}=77.41\times 10^{4}\) km\({}^{2}\) and \(\mathbf{L}=10.11\) km, respectively, and the average thickness of the oil film \(\mathbf{T}=0.40\) mm.  
Figure 6 shows the variation of oil spill head migration distance (\(\mathbf{D}\)), oil film area (\(\mathbf{A}\)), oil spill contamination length (\(\mathbf{L}\)), and average oil film thickness (\(\mathbf{T}\)) with time (from the moment when the crude oil spill stops to the moment when the oil spill head flows out of the modeled river section). It can be seen that \(\mathbf{D}\), \(\mathbf{A}\), and \(\mathbf{L}\) vary monotonically and incrementally with time, and the existence of fluctuations is caused by the irregularity of the river topography. \(\mathbf{T}\) is monotonically decreasing with time. In the pre-spill period, the oil spill aggregation degree is large, and the easy diffusibility of the crude oil itself makes the oil film thickness decrease rapidly, and the decrease rate slows down obviously after \(1\,h\).
# Data Hiding Method for Color AMBTC Compressed Images Using Color Difference
## 2 Related Works  
In this section, we survey the evolution of the BTC-based compression methods, the color image compression methods.  
A lossy compression technique commonly known as Block Truncation Coding (BTC) [10] was introduced in 1979 by [PERSON] and [PERSON]. The BTC first divides the pixels of an original image into sized \(4\times 4\) non-overlapping blocks, then calculates the mean and standard deviation of each block, and then if the pixels in each block are greater than the mean, '1' is assigned, otherwise, '0' is assigned to generate the bit-plane. Finally, two quantization levels representing each block are generated using the mean and standard deviation. BTC provides a relatively high compression performance while the calculation is simple. Since BTC, the method that provides stable performance is Absolute Moment BTC (AMBTC) [11], which was proposed in 1984 by [PERSON] & [PERSON].  
In 1992, [PERSON] and [PERSON] [19] discussed a new block coding for color images, where they introduced a method of constructing a common bit-plane using three rules (majority, luminance, weight). The bit rate was improved using this method. Encoded BTC is further compressed using adaptive DCT coding. Differential coding and residual error feedback techniques have been introduced to reduce the bit rate and improve mean squared error (MSE) [20] performance. The total compression ratio is about 12:1.  
Color image compression moment BTC (CICMPBTC) [21] was proposed by [PERSON] to improve the compression ratio of color AMBTC (CAMBTC) using a traditional method. After generating BTC, the spectral identification code is used to record the quantization level information. This method consumes more time in the compression process than CAMBTC and causes a significant loss in image quality during the compression process.  
[PERSON] et al. [22] discussed the Two-Layer AMBTC scheme (TLAMBTC) to compress color images. Each quantization level is obtained from each of the CAMBTC-based R, G, and B layers divided into blocks. Then, a common bit-plane is derived by using the correlation. The next step is to code the quantization level by subdividing it into \(2\times 2\) blocks. [PERSON] et al. [23] proposed a color image compression method combining block predictive coding and AMBTC, where quantization level coding are for use to compress blocks, respectively. The bit-plane is generated by using appropriate weights to the corresponding R, G, and B components. This method gives a contribution to the MSE performance of the compressed image.  
The problem is that some color components on one plane may not correlate with other planes. Thus, choosing one of the R, G, or B bitmaps is not appropriate and can cause serious noise. To improve this problem, we extract the luminance from each block (composed of RGB) and apply k-means to the luminance (grayscale) of each block. With this, the common bit plane is extracted and used.
## 6 Conclusions  
In this paper, a self-powered SCEC is used as the interface circuit connected to the PMP for harvesting structural vibration energy. In order to optimize the topology structure of the PMPIC, a binary-like topology optimization process is first presented. Then, simulations are conducted to validate the proposed method. The main highlights of this paper may include the following: (i) A binary-like topology optimization approach is first proposed for the PMPIC by dividing the unit cell into a \(\{0,1\}\) matrix indicating material distribution so that the coupled structure and circuit can be optimized simultaneously; (ii) an elastic-electro-mechanical coupling model is built for the coupled PMP and self-powered SCEC with a resonant inductor; (iii) an extended plane wave expansion method is presented to model the bandgap character of the PMPIC, which is numerically solved by the Bloch theorem; (iv) GA is extended to perform topology optimization of the PMPIC by adding the restriction of NIs. In the future, a better approximation of Equation (11) can be studied to replace the long-wave hypothesis in order to increase its accuracy, and fast optimization algorithms need to be explored to reduce the computation cost. In addition, more experimental tests need to be performed to make sure theoretic results. For real-world experiment design, some uncertainties should be addressed and explored in the future, such as fabrication error, nonuniformity of piezoelectrical material, model approximation error, the time delay of the self-powered switch, etc.  
Conceptualization, Z.C. and Y.X.; methodology, Z.C.; validation, Z.C. and Y.W.; formal analysis, Z.C.; writing--original draft preparation, Z.C.; writing--review and editing, Y.X.; project administration, Z.C.; funding acquisition, Z.C. and Y.X. All authors have read and agreed to the published version of the manuscript.  
This study was supported by the National Natural Science Foundation of China, Grant-Number 51911530202 and 51577189, and the Royal Society under the International Exchanges Scheme-Cost Share Programme, Grant Number IEC\(\backslash\)NSFC\(\backslash\)181462.  
Not applicable.  
We thank all the participants in this study.  
The authors declare no conflict of interest.
# Laser Observations of GALILEO Satellites at the CBK PAN Astroegodynamic Observatory in Borowiec
## 3 GALILEO Constellation
By using the onboard atomic clocks of these satellites (hydrogen masers), it is possible to determine the gravitational redshift with high accuracy. Satellite laser measurements have played a crucial role in these studies, enabling a precise estimation of the orbital uncertainties of the GALILEO satellites [29; 30].
# Role of Blockchain Technology in Combating COVID-19 Crisis
## 4 Results
### Applications of Blockchain Technology to Fight against COVID-19
#### 4.4.1 Contact Tracing  
Contact tracing is an essential element of the control of dangerous epidemic outbreaks. It intends to stop disease transfer and has played a role in combating the COVID-19 outbreak in several regions [45]. It is necessary to calculate the cross ponding physical contact of any case during its' incubation period. This can lead to a lower extent of spread that is caused by COVID-19 [36], according to the researchers in [3], the incubation of SARS-CoV-2(COVID-19) for starting the symptoms would take almost 5.5 days, and as described in previous sections, not all infected people got appearing symptoms [3].  
In response to the surprising outbreak of COVID-19, many authorities have presented noticeable trends to mobile contact tracing apps to assist the hard mission of tracking every contact of recently recognized infected people [46]. The social interaction can be determined using contact tracing. It aims to decrease the spread of COVID-19 by taking the initiative which includes giving the individuals the analysis of the virus extent. The analysis is followed by instructions that can be diagnosed, advised, and quarantined in real danger where it is needed. Smartphones and IoT can make this application more effective. Although the users' privacy policy will be violated, the authorities and the healthcare fields adopted the contact-tracing application [36]. The data that are collected  
Figure 4: Contributions of blockchain technology during the COVID-19 pandemic.  
will have high accuracy and reliability if the blockchain is used in high frequency [36]. It gives real-time data for the affected areas. However, the safe zones or free-virus zones are monitored and reported by blockchain [35; 46; 47]. Blockchain technology integrates with other technologies to collect data, such as geographical information systems (GIS) and AI [35; 46].  
Two systems implement the contact tracing: the mass surveillance system and the P2P-mobile application [37; 47]. The mass surveillance system depends on e-Governments and IoT devices within the streets of smart cities. In contrast, the P2P-Mobile application uses services to send the surveillance system and the blockchain network the collected data; it can show users the probability of getting infected by COVID-19 [48].
# Influence of Structural Parameters on Deformation Behavior of Metal Rhombic Chain Mesh
###### Abstract  
Metal net cages, with their wave resistance, corrosion resistance, and anti-fouling properties, have gained attention as promising ecological aquaculture systems. The deformation of netting directly affects the effective culture volume under load. This study aims to explore the deformation resistance of metal diamond chain netting and the impact of structural parameters on its deformation characteristics. Using beam and contact elements, this study employs finite element analysis (FEA) to simulate static deformation and validate the model with experimental results. Simulations under various structural parameters were performed to assess the effects of netting solidity and initial tension on bending deformation under concentrated and distributed loads. The results show that both increased solidity and initial tension lead to enhanced bending stiffness and reduced deformation. Specifically, increasing netting solidity from 0.11 to 0.29 reduces displacement by 53.07% and 68.68%, respectively, and force by 71.89% and 41.55%. Similarly, increasing initial tension from 200 N to 300 N results in minor reductions in displacement (3.48% and 3.52%). This study concludes that netting solidity has a more significant effect on deformation than initial tension, which aligns with the experimental results showing greater reductions in displacement and wire force with increasing solidity. These findings support the model's validity and offer guidance for metallic netting design.  
metal netting; netting deformation; netting solidity; pretension Article
###### Abstract  
The construction industry strongly relies on concrete and clay bricks for various applications. The escalating demand for these materials, driven by rapid population growth, has led to resource depletion and increased construction and demolition waste (CDW). Recycling CDW into construction materials, particularly in the form of recycled concrete aggregates (RCAs) and recycled brick aggregates (RBAs), has emerged as a promising solution. This study deals with the structural performance of concrete incorporating RCAs and RBAs. The experimental program encompasses material characterization, concrete mix design, and several tests to assess density, compressive strength, bond behavior, and flexural properties. The results indicate that the replacement of fine natural aggregate (NA) with fine RCAs or RBAs has a negligible impact on density, while the partial replacement of coarse NAs with RAs yields modest reductions in compressive strength. Notably, the bond strength between steel rebar and concrete is influenced by the type and content of RA, with specimens containing RCAs exhibiting a higher bond strength than those with RBAs. Empirical models used to predict bond strength generally align with experimental results, with conservative predictions by some models, such as ACI 318, and overestimation by others, such as models proposed by AS-3600 and CEB-FIB. The flexural tests of beams highlight the variation in stiffness and load-bearing capacity with the proportion of NAs replaced by RAs. While beams with 50% NA replacement demonstrate comparable performance to control beams, those with 100% RA replacement exhibit lower cracking and yielding stiffness. Cracking patterns in beams with RAs differ from control beams, with RA-containing beams showing more cracks and an altered crack distribution. The findings underscore the feasibility of using recycled aggregates in construction, with partial NA replacement offering a balance between sustainable material usage and desired structural properties.  
reinforced concrete; recycled aggregates; bond strength; flexural performance; sustainable practice +
Footnote †: journal: Applied Sciences
# Control-Flow Integrity: Attacks and Protections
## 2 Memory Errors
### Stack-Based Buffer Overflow  
A stack-based buffer overflow fault is a type of out-of-bounds write where the buffer being overwritten is allocated on the stack (i.e., a local variable or, rarely, a parameter to a function) [21].  
The overflow occurs when data passes over its boundary and writes over the memory, which is not allocated for itself. This error mainly occurs in programming languages that do not use bound checking mechanisms, like C and C++; thus attackers are able to perform such attacks by assigning more inputs than required. Numbered as CWE-121 in the MITRE's CWE list. An example of code containing this fault is presented in Listing 1.  
```
intmain(intargc,char*argv[]){ charbuff[256]; strcpy(buff,argv[1]); }
```  
Listing 1: Stack-based buffer overflow.  
The most frequent fault is caused when manipulating strings because the length of strings (in C and related languages) is not an attribute of the string, but strings are terminated by a delimiter (the null character byte). Therefore, most programmers assume normal or \"well intended\" inputs and do not check the boundaries. It is also hard (in more complex code, not in the one of the example) for the compiler to figure out potential overflows.  
As we will see later, the exploitability of a fault greatly depends on the type of data that can be overwritten; stack buffer overflow is one of the simplest to exploit due to the presence of the return address.