esa-sceva/satcom-chunk-collection huggingface dataset:
## 3 Methodology
### Power Flow Analysis
#### 3.1.1 Network Modeling  
The main components of a distribution network are buses, transmission lines, loads, and generators [41]. Buses serve as connection points where these elements converge, and these buses can be classified into three types:  
* Root Bus: acts as a reference point with a predefined voltage magnitude and phase angle.
* PQ Bus: defines specified levels of active (\(P\)) and reactive (\(Q\)) power.
* PV Bus: specifies active power (\(P\)) and voltage magnitude (\(V\)).  
Transmission lines are represented using a \(\pi\)-equivalent circuit model, which includes both series impedance and shunt admittance. The series impedance \(Z=R+jX\) accounts for resistance (\(R\)) and reactance (\(X\)), while the shunt admittance \(Y\) reflects the line charging effect. This circuit model is illustrated in Figure 3.  
The power generated by the generators at specific buses is expressed as follows:  
\[S_{gen,i}=P_{gen,i}+jQ_{gen,i} \tag{1}\]  
Figure 3: The \(\pi\)-equivalent circuit of an electric power system line.  
Meanwhile, loads are modeled as constant power requirements at each bus:  
\[S_{load,i}=P_{load,i}+jQ_{load,i} \tag{2}\]  
Calculating power flow in distribution systems relies on applying [PERSON]'s laws to determine bus voltages and line currents under steady-state conditions. Due to the distinct features of these systems, such as their high \(R/X\) ratios and predominantly radial topology, traditional power flow methods may not be as efficient. Instead, more tailored approaches, like the forward/backward sweep algorithm [42], are used to leverage the network's radial layout, streamlining the process and improving convergence rates.  
To further enhance the efficiency of these calculations, the use of _BIBC_ (Bus Injection to Branch Current) and _BCBV_ (Branch Current to Bus Voltage) matrices has been introduced. These methods help simplify the mapping of currents and voltages across the network [43].
# Regional Adaptability Analysis of Solar Roof Utilization Technologies in China
## 2 Methodology  
There are many factors influencing the application of solar utilization technologies on building roofs. (1) Solar radiation. Solar radiation is one of the most important factors during the planning, design, and optimization of solar energy systems; therefore, accurate estimation of available solar radiation on rooftops is essential. (2) Building thermal design. Thermal design requirements of buildings change for different climate zones. In the frigid zone and the cold zone, there are higher requirements on the thermal insulation of buildings, while in the hot-summer-and-cold-winter zone and the hot-summer-and-warm-winter zone, there is an emphasis on solar shielding in summer, because the cooling demand of the buildings increases significantly due to the good thermal insulation of the buildings. Therefore, different building requirements for different climate zones will also influence the energy use of the buildings. (3) Economic development level. In economically developed areas, people are more willing to accept solar utilization systems with a longer payback time and a higher economic risk. The initial investment and payback time should be considered with higher priority for such systems in less developed areas in order to reduce economic risks. (4) Architectural design. The design of a building will affect its energy use, demands, and available rooftop area. Different building types follow different requirements in lighting, equipment, and application. (5) Relevant policies and feasibility. Many local governments in China have policies supporting the implementation of solar PV and solar heating systems on building roofs. These policies vary a lot from one region to another; therefore, they must be considered during the design and planning of such systems. The differences in government support and policy are considered in the investigations of the paper.  
This paper will develop new evaluation and zoning methods considering the various influential factors, inclusive solar radiation, thermal climate division, and economic development level. Typical cities from different climate zones will be selected and evaluated using the proposed method. Typical buildings in terms of building types and feature will be identified and analyzed.
## 2 Research Area and Data Sources
### Data Sources Used in This Study
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Data** & **Type** & **Scale** & **Sources** \\ \hline Digital elevation model (DEM) & Raster & 30 m & [[http://gdex.cr.usgs.gov/gdex/](http://gdex.cr.usgs.gov/gdex/)]([http://gdex.cr.usgs.gov/gdex/](http://gdex.cr.usgs.gov/gdex/)) (accessed on 15 \\ November 2020) & & November 2020) \\ \hline Geological data & Raster & 1:500,000 & [[http://geocloud.cgs.gov.cn/](http://geocloud.cgs.gov.cn/)]([http://geocloud.cgs.gov.cn/](http://geocloud.cgs.gov.cn/))\#/portal/home (accessed on 15 November 2020) \\ \hline Annual average rainfall & Datasheet & 30 m & [[http://data.cma.cn/data/detail/dataCode/A.0029.005.html](http://data.cma.cn/data/detail/dataCode/A.0029.005.html)]([http://data.cma.cn/data/detail/dataCode/A.0029.005.html](http://data.cma.cn/data/detail/dataCode/A.0029.005.html)) (accessed on 15 November 2020) \\ \hline Peak ground acceleration (PGA) & Vector & 1:200,000 & [[https://earthquake.usgs.gov/earthquakes/](https://earthquake.usgs.gov/earthquakes/)]([https://earthquake.usgs.gov/earthquakes/](https://earthquake.usgs.gov/earthquakes/)) eventpage/usp000g650/shakemap/pga (accessed on 15 November 2020) \\ \hline Road and river networks & Vector & 1:250,000 & [[https://www.webmap.cn/commres.do?method=](https://www.webmap.cn/commres.do?method=)]([https://www.webmap.cn/commres.do?method=](https://www.webmap.cn/commres.do?method=)) result25W (accessed on 15 November 2020) \\ \hline Seismic intensity & Vector & 1:200,000 & [[https://earthquake.usgs.gov/earthquakes/](https://earthquake.usgs.gov/earthquakes/)]([https://earthquake.usgs.gov/earthquakes/](https://earthquake.usgs.gov/earthquakes/)) eventpage/usp000g650/shakemap/intensity (accessed on 15 November 2020) \\ \hline Land use & Raster & 30 m & [[http://www.webmap.cn/main.do?method=index](http://www.webmap.cn/main.do?method=index)]([http://www.webmap.cn/main.do?method=index](http://www.webmap.cn/main.do?method=index)) (accessed on 15 November 2020) \\ \hline Soil & Raster & 90 m & [[http://www.resdc.cn/data.aspx?DATAID=145](http://www.resdc.cn/data.aspx?DATAID=145)]([http://www.resdc.cn/data.aspx?DATAID=145](http://www.resdc.cn/data.aspx?DATAID=145)) (accessed on 15 November 2020) \\ \hline Landform & Raster & 90 m & [[http://www.resdc.cn/data.aspx?DATAID=124](http://www.resdc.cn/data.aspx?DATAID=124)]([http://www.resdc.cn/data.aspx?DATAID=124](http://www.resdc.cn/data.aspx?DATAID=124)) (accessed on 15 November 2020) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Data sources used in this study.
# A New Method for Detecting Weld Stability Based on Color Digital Holography
## 2 Methods
### The Optical Path of the Color Digital Holography  
The optical path of the color digital holography for detecting the weld stability is shown in Figure 1. The wavelength of the blue laser is 457 nm, the wavelength of the green laser is 532 nm, and the wavelength of the red laser is 671 nm. The pixel size of the charge-coupled device (CCD) (GRAS-50S5M-C) used in the experiment is 3.45 \(\upmu\)m.  
The light waves emitted from the laser are decomposed into reference light and object light after passing through beam splitters (BS) (GCC-4011). Three reference beams are synthesized into white light on BS4, which is then expanded by SF4 and collimated by L1 to form parallel light. Finally, it is refracted into the CCD by BS5. The three beams of object light are, respectively, expanded into spherical waves by spatial filters (GCM-SF03M) (SF1, SF2, and SF3), then diffusely reflected on the surface of the object, and finally, enter CCD through BS5.  
Figure 1 also shows the coordinate system on the optical platform (ZDT-B), where the plane parallel to the surface of the optical platform is defined as the xoz plane in the coordinate system, and the y-axis is perpendicular to the optical platform. Based on the path of the object light, the coordinates of the light points at M8, M9, M10, and OBJECT can be measured to calculate the illumination vectors of the RGB three beams. The distance from the object to the CCD is 840 mm, and the positions of the light points on M8, M9, M10, and OBJECT are (221, 250, 1392), (410, 253, 1593), (679, 250, 1733), and (583, 250, 1111), respectively.
## 8 System Implementation Experimental Studies
### Encoder Implementation  
The encoder was designed with a C language implementation of the encoding algorithm presented in Section 5. Parts of the parity check matrix \(\mathbf{H}_{\text{HR}}\) and \(\mathbf{H}_{\text{IR}}\) are stored in the microcontroller flash memory in the form of positions (indexes) of nonzero submatrices together with corresponding circular shifts, as illustrated by an example in Figure 6.  
We measured the encoding time in the QC-RL-LDPC system with the developed encoder, which was compiled and implemented in the STM32 low-power microcontroller unit. The results are presented in Figure 7. Note that the first part of the encoding (the HR part, shown as chunk-0 in Figure 7) takes a significantly longer time period than the subsequent encoding iterations of the following chunks (the IR part). We also implemented encoders for selected 5G codes, with Base-Graph-1 (BG1, see [17]) and submatrix sizes of 6 and 12, giving codes with information block lengths of 132 and 264, which are similar to our designed codes \(\mathbf{H}3\), \(\mathbf{H}2\) and \(\mathbf{H}5\), respectively. The presented time measurements were then used to assess the energy consumption of the encoder, which is presented in Section 8.4.  
The QC-RL-LDPC encoder stores the parity check matrices in memory using static allocation. Its memory utilization is comparable to the efficient QC-LDPC encoder previously presented by us in [36]. The maximum memory requirement for QC-RL codes is related to the maximum code size, with all chunks. The utilized microcontroller is able to allocate the needed memory and process the encoding.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Matrix** & \(\mathbf{K}\) & \(\mathbf{N_{min}}\) & \(\mathbf{N_{max}}\) & \(\mathbf{R_{max}}\) & \(\mathbf{R_{min}}\) & \(\mathbf{P}\) \\ \hline H1 & 288 & 384 & 720 & 0.75 & 0.4 & 16 \\ \hline H2 & 256 & 384 & 896 & 0.667 & 0.286 & 32 \\ \hline H3 & 144 & 208 & 464 & 0.692 & 0.310 & 16 \\ \hline H4 & 192 & 240 & 600 & 0.8 & 0.320 & 8 \\ \hline H5 & 384 & 480 & 1200 & 0.8 & 0.320 & 16 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Parameters of the QC-RL-LDPC codes used for numerical experiments.  
Figure 6: Parity check matrix of a QC-RL-LDPC code \(\mathbf{H}1\), both HR and IR parts, with submatrix size \(P=16\). The cyclic shift values are provided for nonzero submatrices.
## 2 Materials, Experimental Procedures and Methods
### Experimental Procedures  
#### 2.2.1 Cu Immobilization Experiments  
The GP was reacted with Cu\({}^{2+}\)-bearing solutions at a fluid/solid ratio of 20:1 in 250 mL polyethylene (PE) reactors at 23 \(\pm\) 2 \({}^{\circ}\)C. The Cu/GP mass ratio was set to 1:2, 1:4, 1:8, 1:13 and 1:25, so that these experiments are labeled as Cu:GP-1:2 to Cu:GP-1:25 (henceforth called Cu:GP series). No pH drift corrections were made. All suspensions were stirred at 200 rpm for 24 h. Fluid samples were taken regularly to follow the temporal uptake of Cu\({}^{2+}\) by GP. Reference solutions containing Cu\({}^{2+}\) in the above concentration range (but without GP) were prepared to demonstrate that other mechanisms causing Cu\({}^{2+}\) removal from solution are negligible. Further, a reference experiment with GP but without dissolved Cu\({}^{2+}\) was made to determine the pH development of pure GP in ultrapure water, which equilibrated at pH \(\sim\)11.8. Following up, the effect of pH treatment on Cu\({}^{2+}\) immobilization by GP was studied. The experimental set-up was identical to those described above, except for the adjustment of the solution pH to \(\sim\)11-12 by adding droplets of 1 M sodium hydroxide solution (NaOH, p.a., Roth). This treatment caused less than \(\sim\)2% volume change to the solutions, so that no corrections to the dissolved Cu\({}^{2+}\) concentrations were made. These experiments are labeled as Cu:GP\({}_{\text{pH}}\)-1:2 to Cu:GP\({}_{\text{PH}}\)-1:25 (henceforth called Cu:GP\({}_{\text{PH}}\) series).  
All experiments were terminated after 24 h. The solids were separated by 0.45 \(\upmu\)m cellulose acetate membrane filters (Sartorius, Gottingen, Germany) using a suction filtration unit, rinsed with ultrapure water to remove electrolytes and dried at 40 \({}^{\circ}\)C in preparation for solid-phase analyses. Aliquots were stored under an argon (Ar) atmosphere for subsequent use in ion exchange and leaching experiments. All liquids were acidified using suprapure nitric acid (HNO\({}_{3}\), ROTIPURANR, Roth, Karlsruhe, Germany) in preparation for elemental analyses.
# Light-Induced Ring Pattern in a Dye-Doped Nematic Liquid Crystal
## 3 Mathematical Modeling for Photo-Isomerization in Dye-Doped Liquid Crystals
To describe the dynamics of the photo-isomerization process in the dye-doped nematic layer with planar anchoring, let us consider the concentration of molecules in the _cis_-state \(C(\vec{r}_{\perp},t)\) and the scalar order parameter \(S(\vec{r}_{\perp},t)\), which satisfy the dimensionless rate equations [21; 22]  
\[ \begin{array}{rcl}\partial_{t}C&=&-\lambda[C-C_{0}(I)+\alpha S]+\delta\
abla ^{2}C+D\
abla^{2}S,\\ \partial_{t}S&=&-(A+\beta C)S+B\
abla^{2}-S^{3}+\
abla^{2}S+D\
abla^{2}C.\end{array}  \tag{5}\]  
The \(\alpha\) parameter accounts for the reduction of the _cis_-state concentration when the liquid crystal molecules are more aligned (larger \(S\)) because the dye-dopants tend to be oriented in the direction of the molecules (transition from _cis_ to _trans_) [19]. Indeed, the liquid crystal matrix tends to make the dye-dopants orient and stretch in the direction of the molecular order. The parameter \(\beta\) stands for the entropic effect of the photo-isomerization process; that is, by increasing the concentration of the _cis_ molecules, the disordered or non-oriented state is favored. Then, the linear term in S must decrease if the dye-dopant concentration increases. The parameter \(D\) accounts for the mutual transport process; namely, a gradient in the dopant concentration induces the propagation of the order parameter [35]. In the limit of the large-scale separation between the order parameter S and the concentration of the _cis_-state (\(\lambda\gg 1\)) and for small \(\alpha\) and intensity \(I\), the cis-state concentration satisfies  
\[C=C_{0}(I)\approx\gamma I=\gamma I_{0}e^{-r_{\perp}^{2}/w^{2}}. \tag{6}\]  
Therefore, the cis-state concentration acquires a Gaussian profile. Using this expression in the equation of the order parameter, \(S\) satisfies the Landau-De-Gennes model for the nematic to isotropic transition induced by photo-isomerization [20]. Indeed, the bifurcation parameter \(A(I)\equiv A+\beta\gamma I\) is controlled by the light intensity profile. When the sample is not illuminated, the system is in a NLC phase (\(S_{+}\)). When the sample is illuminated, the light can induce front propagation from the isotropic (\(S_{IS}\)) to the nematic phase [20].
# Environmental Impact of the Natural Gas Liquefaction Process: An Example from China
###### Abstract  
Considering its clean and environmental characteristics, natural gas has gradually attracted attention from countries around the world. China's coal-to-gas project has significantly increased the country's demand for, and supply of, natural gas. Liquefied natural gas (LNG) has also been gradually promoted, owing to its advantages of easy storage and transportation. However, the natural gas liquefaction process includes multiple phases, and each phase generates substantial industrial pollutants, such as CO\({}_{2}\), SO\({}_{2}\), and NOx. Despite this, the resulting environmental impacts have not been quantitatively assessed. Therefore, based on the production process of a liquefaction plant in the Shanxi Province, China, in this study, the Life Cycle Assessment (LCA) model was used to analyze the pollutant discharge in the unit's natural gas liquefaction production process. By collecting data on the production capacity and composition reports of the eight major LNG-producing provinces, such as Henan, Sichuan, Inner Mongolia, Shaanxi, Xinjiang, Shanxi, Ningxia, and Hebei, the total amount of pollutants discharged from the natural gas liquefaction process in China was estimated. Finally, the environmental impact of the natural gas liquefaction process was evaluated according to the results of the environmental impact of pollutants. Our study arrived at the following conclusions: (i) 93.60% of China's natural gas liquefaction output is concentrated in eight provinces; (ii) in terms of the unit's LNG production, the Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), Photochemical Ozone Creation Potential (POCP) and Dust Potential (DP) proportions of each province explained the gas composition of LNG production gas sources in each province; (iii) the environmental problems caused by natural gas liquefaction were different in each provinces. In addition, we suggested relevant policy recommendations. First, the formulation of LNG-related policies should consider environmental pollution produced during the liquefaction stage. Second, if the problem of pollutant discharge in the liquefaction of natural gas is properly solved, it will not only reduce environmental pollution, but also generate additional income. Third, different provinces should optimize production technology based on the different gas qualities.  
natural gas liquefaction; environmental impact; LCA; China +
Footnote †: journal: Applied Physics Letters
# Investigation of Nanogrids for Improved Navy Installation Energy Resilience
## 3 Methodology
### Step 2: Develop and Down-Select Nanogrid Architectures
#### 3.2.2 Step 2.2: Develop One-Line Nanogrid and Microgrid Designs  
Once the AoA is conducted a high-level one-line diagram of the microgrid and proposed nanogrids can be developed. All critical loads, existing DER, other existing power infrastructure (e.g., power lines, transformers, etc.), and proposed nanogrids should be included. This one-line diagram serves as the basis for further analysis within this method. Note that at this point, we are interested in including _all_ potential nanogrids as a down-select step to choose which nanogrids should be implemented occurs later.
# Effect of Inense Ash on the Engineering Properties of Cement-Based Composite Material
###### Abstract
[20] replaced a portion of cement with the ash of joss paper and found that doing so resulted in greater long-term compressive strength of the concrete. [PERSON] et al. [21] observed through scanning electron microscopy (SEM) that replacing cement with the fly ash of biomaterials affected the durability of cement mortar. Researchers have also explored the use of industrial byproducts collected from channels such as coconut husk ash [22; 23], hemp fiber [24; 25], wood ash [26], and agave ash [27], which were ground or cut into a suitable size before being added into structural materials. Incense ash is 8-15% alkali metals, most of which is K (13%). The presence of alkali metals raises the pH of incense ash solution, making molecules require more kinetic energy to form embryo crystallites. Consequently, the presence of alkali metals increases the number of Ca(OH)\({}_{2}\) and C-S-H unit cells in incense ash solution. Upon contact with water, innumerable micropores form on the surface of ash grains, facilitating the invasion of water molecules. At this moment, Si\({}^{4+}\) ions detach from the surface and inside of ash grains and form silicate complexes, increasing the water retained in ash grains. Because the water-saturated incense ash contains large numbers of Ca and Al ions, when ash grains are wrapped by silicate, the high concentration of impurities in the grains increases the activation energy and degrees of freedom of these ions, enabling them to form unit cells that gradually expand and fill the micropores, thereby making the grains more compact and enhancing their compressive strength [28]. Most types of biomass ash can improve the long-term strength of concrete. Therefore, to make incense ash more effective and to achieve desirable early strength in concrete, curing temperatures must be investigated. Under a high curing temperature, the high activation energy increases the number of collisions between cement grains, hastening their hydrated reaction and in turn increasing the early strength of concrete [29]. The amount of Ca(OH)\({}_{2}\) produced increases with the curing temperature, thus promoting a pozzolanic reaction by increasing cement's contact with SiO2 and Al2O3 in the ash [30]. Biomass ash has been used in structural concrete, but reports on the use of and relevant research on incense ash, which can be considered a special product of Taiwan, are scarce. If a method can be established to make use of incense ash, the effectiveness of incense ash can be ascertained. The material may become a resource that can be recycled for use in the concrete industry, with the dual benefits of waste reduction and environmental protection.
# Efficient User-Serving Scheme in the User-Centric Cell-Free Massive MIMO System
## 1 Introduction
* In order to keep the computational complexity and fronthaul requirements to a realistic level, conjugate beamforming (CB) is used for precoding, and the equal gain algorithm is used for power control [8; 13]. Each AP performs channel estimation locally, and the channel model used in this paper is assumed to be flat fading [10; 11]. In addition, all APs support users as the number of installed antennas. * The proposed scheme is derived from the distribution of per-user throughput. It is shown that the majority of per-user throughput is obtained from only a few APs. Based on this observation, the unserved users can be served while existing user data rates are maintained. By applying the proposed scheme, it is possible to obtain an improved per-user throughput through the cumulative distribution function (CDF) for the worst 10% of users compared to the previous scheme in [20] with many users, and also to achieve an improved sum throughput and BER performance. * In this paper, the sum rate performance simulation is conducted in several situations for comparison. For sensitivity analysis, the situation where perfect channel state information (CSI) or channel estimate is applied is compared, and a simulation is performed on the effect of the limitation on the number of pilot sequences. This paper is organized as follows: In Section 2, the network model and downlink spectral efficiency are described. In Section 3, the observation of distribution for per-user throughput is shown. Section 4 discusses the proposed scheme algorithm and the complexity. The power control and pilot assignment method are also explained. Section 5 provides the simulation results, and Section 6 summarizes the paper. Table 1 describes the notations and symbols used in this paper.