esa-sceva/satcom-chunk-collection huggingface dataset:
# A Brief Review of Mueller Matrix Calculations Associated with Oceanic Particles
## 5 Conclusions  
A general introduction for calculating the Mueller matrix of suspended particles in the ocean is given. The surface and volume integral equations of the electromagnetic field can be given from [PERSON]'s equations. Also, the amplitude scattering matrix and the Mueller matrix with respect to light scattering can be defined to describe the polarization state of a suspended particle. To calculate the amplitude scattering matrix and Mueller matrix, the scattering methods are introduced based on the following categories: numerically exact methods, semi-analytical T-matrix methods, and geometric optics methods. For clarity, three typical methods: the DDA method, the IITM, and the PGOM, are briefly presented. Moreover, the Mueller matrix of an arbitrarily generated hexahedron particle under the random orientation condition is computed while using the ADDA and the IITM when the volume equivalent sphere radius is 1 \(\upmu\)m and using the PGOM and the IITM for a volume equivalent sphere with a radius of 8 \(\upmu\)m, while the incident wavelength is 0.658 \(\upmu\)m. Perfect agreement between the ADDA and the IITM are given since both methods are considered to be the exact solutions. The IITM is more computationally efficient than the ADDA when the particle is under the random orientation condition. Excellent agreement between the PGOM and the IITM are obtained especially for the forward and the backward scattering directions. The PGOM is more computationally efficient than the IITM because of the ray-tracing process. Consequently, the Mueller matrix of suspended particles can be computed by using numerically exact methods, T-matrix methods, and the physical-geometric optics method to cover a complete size range.  
Figure 4: Comparisons of Mueller matrix elements of a hexahedron particle calculated by the IITM and the physical-geometric optics method (PGOM). The volume equivalent sphere radius is 8 \(\upmu\)m and the incident wavelength is 0.658 \(\upmu\)m. The relative refractive index is 1.12 + i0.0005.  
**Author Contributions:** Conceptualization, G.W.K.; Methodology, B.S., P.Y., X.Z. and G.W.K.; Software, B.S.; Validation, B.S., P.Y. and X.Z.; Writing-Original Draft Preparation, B.S., P.Y. and X.Z.; Writing-Review & Editing, B.S., P.Y., X.Z. and G.W.K.; Visualization, B.S.; Supervision, P.Y. and G.W.K.; Project Administration, P.Y.; Funding Acquisition, P.Y. and X.Z.  
**Funding:** This research was partly supported by the National Science Foundation (OCE-1459180) and the endowment funds related to the [PERSON] Chair in Geosciences at the College of Geosciences, Texas A&M University.  
**Acknowledgments:** This research were conducted with high performance research computing resources provided by Texas A&M University.  
**Conflicts of Interest:** The authors declare no conflict of interest.
# Design and Application of a Distribution Network Phasor Data Concentrator
###### Abstract  
The wide area measurement system (WAMS) based on synchronous phasor measurement technology has been widely used in power transmission grids to achieve dynamic monitoring and control of the power grid. At present, to better realize real-time situational awareness and control of the distribution network, synchronous phasor measurement technology has been gradually applied to the distribution network, such as the application of micro multifunctional phasor measurement units (\(\upmu\)MPMUs). The distribution network phasor data concentrator (DPDC), as a connection node between the \(\upmu\)MPMUs and the main station, is also gaining more attraction. This paper first analyzes the communication network structure of DPDCs and \(\upmu\)MPMUs and compares and analyzes the differences in the installation locations, functions, communication access methods and communication protocols of the phasor technology devices of the distribution network and the transmission network. It is pointed out that DPDCs not only need the functions of data collection, storage, and forwarding like transmission network PDCs, but also should be able to access more \(\upmu\)MPMUs, and can aggregate the phasor data of the same time scale from \(\upmu\)MPMUs by different communication methods. The communication protocol selected by DPDC should be expanded to support remote control, telemetry, fault diagnosis and other functions of distribution automation. The application requirements of DPDCs are clarified, and the key indicators of DPDCs are given as a method to evaluate the basic performance of DPDCs. Then, to address the problems of more \(\upmu\)MPMU access, abnormal communication, and data collection with different delays that DPDC encountered, a DPDC that considers multiple communication methods is designed. Based on the Linux system and the libuv library, the DPDC is designed with event-driven mechanism and structured programming, runs multiple threads to implement multitasking, and invokes callbacks to perform asynchronous non-blocking operations. The DPDC test system and test methods are designed. The performance of the designed DPDC is evaluated through the test and the test results are analyzed. Lastly, its real-world application is disclosed, which further confirmed the value of our DPDC.  
distribution network; PDC; key performance indicators; test +
Footnote †: journal: Applied Sciences
## 3 Results
### Validation  
To validate the analytic coordinates of the Sun and Moon, our results were compared with planetary ephemerides. As mentioned in Section 1, the DE is one of the main streams of planetary ephemerides. The DE430 was selected because of the improvements based on the use of additional lunar laser ranging data and improved lunar gravity field for the lunar orbit and attitude. For the lunar position, the coordinates based on DE 430 were tabulated as the origin at the Earth barycenter, that is, the geocentric celestial reference system. The lunar attitude is expressed by three Euler angles based on the DE 430 [24].  
We assumed that the sensor was equipped at (0\({}^{\circ}\), 0\({}^{\circ}\)) on the Moon and the observed point was located at (0\({}^{\circ}\), 0\({}^{\circ}\)) on the Earth. Notice that the mean orbital elements of the Sun and Moon are adopted with respect to the Earth and the ecliptic for decades around the year 2000 [38]. Figure 2 shows comparisons between the results derived from DE430 and our method during one orbital period. Note that the orbital period refers to the period it takes the Moon to complete one revolution relative to the Sun (a synodic month). Considering the relative azimuth angle is defined as the angle between the Moon and Sun, the \(x\)-axis represents the time when the observed point was simultaneously visible by the Moon and Sun. The \(y\)-axis represents the results for the three observational angles. The blue and orange lines represent the angles calculated using DE430 and our proposed method, respectively. The results derived from our proposed method almost coincide with those obtained from DE430, within 1\({}^{\circ}\) of error, verifying the correctness and validity of our analytical method.
# ReDSHIFT: A Global Approach to Space Debris Mitigation
## 6 Conclusions  
After more than two years of work, the H2020 ReDSHIFT project has already reached a number of interesting goals which were briefly summarized in the above sections. In particular, we can highlight:  
* a complete mapping of the LEO to GEO space was performed and the cartography was exploited to devise \"dynamical\" disposal strategies for any orbital regime.
* a prototype small spacecraft \"debris compliant\" was designed and assembled, exploiting the advantages offered by the additive manufacturing procedures. Several parts, including optimized debris shields, were designed and 3D printed.
* the materials and components of the spacecraft were tested for Design for Demise (D4D). Moreover the D4D tests included a novel test on an engineering model of a reaction wheel.
* the possibility to exploit area augmentation devices (e.g., solar and drag sails) was studied both from the dynamical and the hardware point of view.
* a software tool (whose web version will be made public at the end of the project) encompassing all the above findings was produced. The software shall help the users to conceive a \"debris compliant\" space mission from the design to the disposal phase.
* the possible improvements to the international space regulations and standards, stemming from the project's findings, were analyzed.  
[PERSON] is the coordinator of ReDSHIFT and the main writer of this document. [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] contributed mainly to the results in Sections 2 and 4. [PERSON], [PERSON] and [PERSON] contributed mainly to the results in Section 3.2. [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] contributed to the results in Section 3. [PERSON] and [PERSON] contributed to the results in Section 3.1. [PERSON] contributed to the results in Section 4. [PERSON] and [PERSON] contributed to the results in Section 5.  
**Acknowledgments:** The research leading to these results has received funding from the Horizon 2020 European Union's Framework Programme for Research and Innovation (H2020-PROTEC-2015) under REA grant agreement n. [687500]--ReDSHIFT. The authors also express their gratitude to the ESA/ESOC Space Debris Office for granting permission to use the MASTER 2013 reference population in the context of ReDSHIFT.  
**Conflicts of Interest:** The authors declare no conflict of interest.
## Featured Application: Optical light communications.  
**Abstract:** A light signal transmitter based on ultraviolet radiation is realized on GaN-on-silicon platform. The light signal transmitter with ultra-small active area is fabricated by a double-etching process. The absolute value of negative junction capacitance of transmitter is as low as the pF (picofarads) scale in positive bias voltage. Small capacitance is beneficial to improve the communication performance of a transmitter. The dominant EL (electroluminescence) peak of transmitter is located at about 380 nm in the ultraviolet range. With the increase of the current, the dominant peak of transmitter remains stable and the light output power is lineally modulated. A free-space data transmission test in the ultraviolet range with 250 Mbps was conducted to indicate a promising high-speed optical communication capability of a light signal transmitter in the ultraviolet range.  
**Keywords:** LED (light emitting diode); ultraviolet; GaN; optical communication
# Machine Learning Ship Classifiers for Signals from Passive Sonars
## 3 Classifier Models
### Ridge Regression  
Ridge regression is a linear regression that adds a regularization term to ordinary least squares (OLS) regression to prevent overfitting by penalizing large coefficients, which is an extension of OLS with \(\ell_{2}\) regularization [29]. In linear regression, the goal is to find the coefficients \(\beta\) that minimize the sum of the squared differences between the actual and predicted values. The objective function for OLS is  
\[\text{Min}\quad\frac{1}{n}\sum_{i=1}^{n}(y_{i}-\hat{y}_{i})^{2}=\frac{1}{n} \sum_{i=1}^{n}(y_{i}-X_{i}\beta)^{2},\]  
where \(y_{i}\) is the actual value of the target variable, \(\hat{y}_{i}=X_{i}\beta\) is the predicted value (with \(X_{i}\) being the vector of input features for sample \(i\), and \(\beta\) the coefficient vector), and \(n\) is the number of samples. This minimizes the residual sum of squares (RSS); however, if there are highly correlated features or a small dataset, OLS tends to overfit, leading to large unstable coefficients.  
Ridge regression addresses the overfitting problem by adding a penalty term to the OLS objective function. This penalty is proportional to the square of the magnitude of the coefficients; that is, \(\ell_{2}\) regularization:  
\[\text{Min}\quad\frac{1}{n}\sum_{i=1}^{n}(y_{i}-X_{i}\beta)^{2}+\lambda\sum_{j =1}^{p}\beta_{j}^{2},\]  
\(\lambda\) is a regularization parameter that controls the strength of the penalty, \(\beta_{j}\) are the coefficients of the regression model, and \(p\) is the number of features.  
The objective is a combination of fitting the model to minimize the sum of squared errors (SSR) and penalizing the size of the coefficients \(\beta_{j}^{2}\) so that the large coefficients shrink toward zero.
## 2 Generic Pathways for Plant Response to Abiotic Stresses
### Ca2+ Ions  
As reported by many articles, the most important universal secondary messenger is calcium ions (Ca2+). As mentioned before, salinity and drought stresses cause ionic and osmotic stresses for the exposed plant. Hence, the plants adapt to the stresses by retaining the cellular homeostasis by dealing with osmotic and ionic stresses. It was discovered that the Salt Overly Sensitive (SOS) genes are a primer mediator for the ionic hemostasis in plants. _SOS3_ gene encodes for a protein that acts as a receptor for cytosolic Ca2+[32]. Increased levels of Ca2+ lead to the activation of the cascade of events that would activate the genes responsible for protecting the plant from salt stress. For instance, the _SOS1_ gene encodes for the plasma membrane Na+/H+ antiporter, and the _SOS1_ gene is mediated by the _SOS2_, which encodes for a calcium-dependent protein kinase (CDPK) [32; 33; 34]. The plasma membrane Na+/H+ antiporter aids in protecting the plant from salinity stress by maintaining the osmotic balance by compartmentalizing Na+ and chloride into vacuoles or extruding the excessive toxic Na+ to the apoplast or surrounding tissues [35; 36; 37; 38]. Along with SOS, Ca2+ ions cooperate with other signaling molecules, including calcium-dependent protein kinases (CDPKs), which are considered very important phosphorylating agents in the plant response to abiotic stresses [39].  
CDPKs play important roles at the cellular and molecular level in plants: increasing the resistance and adaptation to abiotic stress and modulating metabolic pathways [40]. The CDPKs play a significant role in the biosynthesis of important organic molecules by phosphorylating and activating a variety of biosynthetic metabolic pathways. [PERSON] discovered that a key enzyme in the defense response against abiotic stress, known as the phenylalanine ammonia lyase (PAL) enzyme, could be phosphorylated by a CDPK isoform [41], indicating its connection to the secondary metabolite biosynthetic pathways and abiotic stress resistance.
###### Abstract  
Approximating the complex nonlinear relationships that dominate the exchange of carbon dioxide fluxes between the biosphere and atmosphere is fundamentally important for addressing the issue of climate change. The progress of machine learning techniques has offered a number of useful tools for the scientific community aiming to gain new insights into the temporal and spatial variation of different carbon fluxes in terrestrial ecosystems. In this study, adaptive neuro-fuzzy inference system (ANFIS) and generalized regression neural network (GRNN) models were developed to predict the daily carbon fluxes in three boreal forest ecosystems based on eddy covariance (EC) measurements. Moreover, a comparison was made between the modeled values derived from these models and those of traditional artificial neural network (ANN) and support vector machine (SVM) models. These models were also compared with multiple linear regression (MLR). Several statistical indicators, including coefficient of determination (\(R^{2}\)), Nash-Sutcliffe efficiency (NSE), bias error (Bias) and root mean square error (RMSE) were utilized to evaluate the performance of the applied models. The results showed that the developed machine learning models were able to account for the most variance in the carbon fluxes at both daily and hourly time scales in the three stands and they consistently and substantially outperformed the MLR model for both daily and hourly carbon flux estimates. It was demonstrated that the ANFIS and ANN models provided similar estimates in the testing period with an approximate value of \(R^{2}\) = 0.93, NSE = 0.91, Bias = 0.11 g C m\({}^{-2}\) day\({}^{-1}\) and RMSE = 1.04 g C m\({}^{-2}\) day\({}^{-1}\) for daily gross primary productivity, 0.94, 0.82, 0.24 g C m\({}^{-2}\) day\({}^{-1}\) and 0.72 g C m\({}^{-2}\) day\({}^{-1}\) for daily ecosystem respiration, and 0.79, 0.75, 0.14 g C m\({}^{-2}\) day\({}^{-1}\) and 0.89 g C m\({}^{-2}\) day\({}^{-1}\) for daily net ecosystem exchange, and slightly outperformed the GRNN and SVM models. In practical terms, however, the newly developed models (ANFIS and GRNN) are more robust and flexible, and have less parameters needed for selection and optimization in comparison with traditional ANN and SVM models. Consequently, they can be used as valuable tools to estimate forest carbon fluxes and fill the missing carbon flux data during the long-term EC measurements.  
carbon fluxes; boreal forests; machine learning; eddy covariance; adaptive neuro-fuzzy inference system; generalized regression neural network +
Footnote †: journal: Journal of the American Statistical Association
# The XTRA Option at the NEUTRA Facility--More Than
## 1 Introduction-Method and Instrumentation  
X-ray and neutron-transmission imaging are used for non-destructive measurements of samples originating from a broad range of application areas. Whereas X-ray imaging is well known from its medical applications, neutron imaging is more suitable for transmission through materials like metals or minerals. This is due to the different types of radiation-matter interactions, which for X-rays is proportional to the electron density of a material, i.e., it scales with the number of electrons in the atom, whereas the neutron interacts with the atomic nuclei. Combining both neutron and X-ray measurements of a specific sample allows for the use of the different contrast mechanisms provided by these two imaging modalities to enable enhancements of the information obtained for a sample. By implementing an X-ray source in the neutron imaging instrument NEUTRA [1], we enabled both X-ray and neutron imaging capabilities within a single facility, available for external users at the spallation neutron source SINQ of the Paul Scherrer Institute. This article provides an overview of the facility, but in particular a retrospective of this pioneering installation and its results as a forerunner of bi-modal neutron and X-ray imaging, which is now available or planned for at many leading neutron imaging instruments worldwide, including ICON at PSI, Switzerland; NEXT at ILL Grenoble, France; nEXT at NIST, USA; ODIN at ESS, Sweden; and VENUS at ORNL, USA. Compared to the XTRA setup with its sequential approach, the before mentioned facilities prefer a simultaneous scanning with the source/detectors perpendicular to each other, viewing the sample at the same time. In these cases, the beam geometry cannot be identical, and the comparison can only be done after reconstruction of the data on the voxel level.
# The Evolution and Development Trends of LNG Loading and Unloading Arms
## 3 Development of Land-Used LNG Loading and Unloading Arms
### Land-Used Loading Arm Actuation and Its Intelligence and Automation
With the continuous development of visual recognition technology and the motion control system of loading and unloading arms, the automatic docking of loading and unloading arms will become more stable, precise, and reliable.
## 4 Results
### Denoising Results for Real Data
#### 4.2.1 Denoising Results for Ex Vivo Porcine Cardiac DTI  
Figure 4 shows the denoising results obtained with different methods on an ex vivo porcine dataset. We observe that the residual values of the DW images generated with BM3D, DIP, NB2 NB, and SSECNN are so big that they can not accurately estimate the cardiac fiber orientations or FA and MD maps from the denoised DW images. For instance, the denoised fiber orientations of BM3D and NB2 NB are totally disarranged, and the FA values are much higher than those in the noisy ones, while the MD values are much smaller. However, LPCA, AONLM, P2S, and the proposed Node2 Node result in small residuals in DW images. In particular, in our proposed model, Node2 Node, and LPCA, the residual maps are homogeneous with small values and without structure information. However, the blurring effects of LPCA over Node2 Node on FA and MD maps can also be observed. In terms of HA and TA maps, besides BM3D, all the methods can restore the helix and transverse angle distributions, but the TA maps obtained through DIP, NB2 NB, and P2S are a little noisy.
# FPGA-Based Linear Detection Algorithm of an Underground Inspection Robot
## 5 Conclusions  
In this paper, based on the LSD algorithm, a line segment detection algorithm IP core suitable for an FPGA platform is constructed for the needs of the conveyor belt deviation fault diagnosis. The algorithm module integrates four sub-modules: image preprocessing,  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Resource Category** & \
\begin{tabular}{c} **Algorithm Module** \\ **Occupancy** \\ \end{tabular} &
\begin{tabular}{c} **FPGA Available** \\ **Resources** \\ \end{tabular} & **Occupancy (\%)** \\ \hline Slice LUTs & 3284 & 53,200 & 6.17 \\ FF & 3925 & 106,400 & 3.70 \\ BRAM & 29.50 & 140 & 21.07 \\ DSP & 12 & 220 & 5.45 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Resource occupancy of the line segment detection algorithm.  
Figure 20: Algorithm clock delay analysis.  
gradient information calculation, edge detection, and region growth. After experimental verification, the hardware algorithm constructed in this paper is shown to accurately detect the line segment area, with angles from 45\({}^{\circ}\) to 135\({}^{\circ}\) in the image, and has good stability. Moreover, the logic resource occupied by the IP core is moderate. Taking the clock frequency of 100 MHZ as an example, the processing frame rate of the algorithm can reach 108 FPS, which meets the requirements of real-time processing.  
Conceptualization, C.Z. and S.C.; investigation, S.C.; methodology, C.Z. and S.C.; project administration, L.Z. and X.L.; resources, X.M. and X.L.; software, S.C., X.L., and L.Z.; supervision, X.M.; validation, C.Z.; writing--original draft, S.C. and X.L.; writing--review and editing, S.C. and X.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China: Research on the Integrated Control Method of the Lateral Stability of Distributed Drive Mining Electric Vehicles (51974229), the Shaanxi Provincial Department of Education Science and Technology Plan Project Enterprise Joint Fund (2019 JLP-06), the Shaanxi Province Innovative Talent Promotion Plan--Science and Technology Innovation Team (2021 TD-27), and the National Key Research and Development Program, China (No. 2018 YFB1703402).  
Not applicable.  
The authors declare no conflict of interest.