esa-sceva/satcom-chunk-collection huggingface dataset:
## 2 Study Area and Materials
### Data  
The network of rainfall gauges in the study area is characterized by its dense and evenly distributed nature, ensuring reliable data quality and high accuracy of the observations. The observation data used in this study were obtained from gauges operated by the Fujian Provincial Bureau of Hydrology, which are not classified as international exchange stations. The spatial distribution of meteorological stations can be seen in Figure 1, with a total of 15 rain gauges in the entire basin. Hourly data from 425 rainfall events from 2006 to 2018 were selected as the research data. The training period was from 2006 to 2014, and the testing period was from 2015 to 2018. The dataset was prepared through sliding windows,  
Figure 1: Location of the study area and spatial distribution of rain gauges.  
resulting in a training set with a sample size of 272,916 and a test set with a sample size of 109,858.  
To evaluate the accuracy improvement of the fusion model for different magnitudes of rainfall data, the maximum 12 h cumulative rainfall was calculated based on the selected 425 rainfall events. Rainfall was classified into four categories: light, moderate, heavy, and torrential, based on their magnitude as per the classification criteria listed in Table 1.  
The satellite precipitation data were obtained from the Integrated Multi-Satellite Retrievals for Global Precipitation Measurement Mission (IMERG). Global Precipitation Measurement (GPM) is an international satellite mission conducted by the National Aeronautics and Space Administration (NASA) and Japan Aerospace Exploration Agency (JAXA), which uses multi-sensors, multi-satellites, and multi-algorithms combined with satellite networks and rain gauge inversion to obtain more accurate precipitation data. IMERG algorithm is designed to calibrate, combine, and interpolate satellite microwave precipitation estimates from the TRMM and GPM, as well as microwave-calibrated infrared satellite estimates, precipitation measurement analyses, and potentially other precipitation estimates. It has now been updated to product version V06B. This study uses GPM (IMERG V06) Final Run data with a spatial resolution of 0.1\({}^{\circ}\) and a temporal resolution of half an hour from January 2006 to December 2018 ([[https://earthdata.nasa.gov/](https://earthdata.nasa.gov/)]([https://earthdata.nasa.gov/](https://earthdata.nasa.gov/)); accessed on 15 October 2022).
# Experimental Study of a Signal Modulation Method to Improve eLORAN Data Channel Communications
## 3 Results
### Experimental Results
#### 3.3.2 Result Analysis  
All test times were selected as day, because the night sky wave signal is enhanced, which will cause serious cross interference. The time of arrival (TOA) value of the eLORAN receiver is as shown in Figure 10. At all the test points, the TOA value is less than 37.5 \(\upmu\)s, it can be determined that the receiver is locked to the ground wave signal.  
Figure 9: Test site distribution.  
At the XJSS test point, the TOA value has reached 31 us, as shown in Figure 10, indicating that the sky wave signal has caused serious interference to the ground wave signal. The rising edge of the eLORAN pulse signal lags behind and the signal is distorted, as shown in Figure 11, causing deviations in standard zero-crossing detection. The performance of the standard zero crossing determines the error of the TOA value.  
The standard zero crossing (SZC) is the positive zero crossing at the point 30 microseconds into a positively phase coded pulse on the antenna-current waveform, as shown in Figure 12. Given in [7], this zero crossing is phase-locked to the eLORAN station's cesium time reference. The standard zero crossing is used as a timing reference for measurement of eLORAN signal specifications.  
It can be seen from Table 3 that as the distance from the BPL station is increasingly further away, the decoding success rate of 3S-PPM and APM signals decreases. When field strength of the ground wave signal is weakened, such as the XJSS test point, the field strength has reached the minimum limit specified by RTCM, the demodulation success rate of 3S-PPM is greatly reduced, while the demodulation success rate of APM has maintained a high level. When the field strength of the test point becomes weaker, it is more susceptible to noise interference, which will cause difficulty in standard zero-crossing detection, and the error of TOA measurement results will increase. The demodulation success rate of 3S-PPM will decline rapidly, while the demodulation success rate of APM will still maintain a high level. However, at the same test point, the decoding success rate of APM signal is higher than that of 3S-PPM signal, which is consistent with the result of theoretical analysis.  
Figure 11: XJSS test point waveform.  
Figure 10: TOA error.
# High Frequency Transformers for Solid-State Transformer Applications
## 5 Conclusions  
SST's are increasingly used to replace traditional transformers (50/60 Hz) because of the many advantages they provide, such as smaller dimensions, higher power density, ease of integration with alternative systems, supply of loads in direct current, and integration of systems for the improvement of power quality, among others. However, utilizing HFTs instead of low frequency transformers may present higher costs because numerous power components and auxiliary control circuits are required, which can be relatively complex and expensive.  
Several simulation tests were performed in Matlab/Simulink on the application of the SST to a fast charger of an electric vehicle supplied by an electrical network. In these simulation tests, an efficiency of around 99.5% was obtained for a 50 kVA constant resistive load operating at 1 kHz. Another test was also performed, in which the load was changed from 25 kVA to 50 kVA. Despite the extreme load variation, the controller presented good performance and fast stabilization. The maximum efficiency was 99.7% obtained at 25 kVA. The bidirectionality power flow of the solution was also tested and confirmed, showing a gradual transition from battery charging (Grid-to-Vehicle--G2V) to battery discharging (Vehicle-to-Grid--V2G) while the phase shift angle changed from positive to negative values to regulate the power delivered to the load.  
According to the simulation results obtained, all our objectives were verified, such as the validation of the theoretical model of the HFT, the validation of the control scheme developed for SST control, and the verification of the ability to support power bidirectionality. Furthermore, temporal evolutions and efficiency values consistent with the theoretical concepts were obtained.  
Figure 14: Temporal voltage evolution at of the terminal’s transformer.  
**Author Contributions:** Conceptualization, N.S. ([PERSON]), M.C. and P.G.; methodology, N.S. ([PERSON]), M.C. and P.G.; software, N.S. ([PERSON]); investigation, N.S. ([PERSON]); writing--original draft preparation, N.S. ([PERSON]); writing--review and editing, N.S. ([PERSON]), M.C., P.G., A.C., N.S. ([PERSON]) and S.F.P.; visualization, N.S. ([PERSON]), M.C., P.G., A.C., N.S. ([PERSON]) and S.F.P.; supervision, N.S. ([PERSON]), M.C. and P.G. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work was supported through funds from Fundacao para a Ciencia e Tecnologia (FCT) with project reference UIDB/50021/2020 and and PTDC/EEI-EEE/32550/2017.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** Not applicable.  
**Acknowledgments:** The authors acknowledge the project funded by the Fundacao para a Ciencia e a Tecnologia (FCT) PTDC/EEI-EEE/32550/2017--Smart Transformer for Sustainable Grids.  
**Conflicts of Interest:** The authors declare no conflict of interest.
## 3 Materials and Methods
### Quality Control Data (QCD)
#### 3.4.3 Geo-Accumulation Index (Igeo)  
The Geo-accumulation Index (Igeo) is calculated using the following equation:  
\[\text{Igeo}=\text{Log}_{2}(\text{Cn})/1.5(\text{Bn})\]  
where Cn is the measured concentration of a given metal in the sediment, and Bn is the corresponding geochemical background concentration. The constant factor 1.5 serves as a background matrix correction factor, accounting for possible variations in the lithogenic background due to natural fluctuations in the environment.  
The Igeo scale, originally introduced by [PERSON] [46; 47], categorises sediment contamination into seven distinct classes: Class 0 (practically unpolluted): Igeo \(\leq\) 0; Class 1 (unpolluted to moderately polluted): 0 < Igeo < 1; Class 2 (moderately polluted): 1 < Igeo < 2; Class 3 (moderately to heavily polluted): 2 < Igeo < 3; Class 4 (heavily polluted): 3 < Igeo < 4; Class 5 (heavily to extremely polluted): 4 < Igeo < 5; and Class 6 (extremely polluted): 5 > Igeo [22; 48].
# Measuring the Centrality of DNS Infrastructure in the Wild
## 1 Introduction
Furthermore, we found that 60% combinations of name server providers share their infrastructure directly or indirectly, which suggests that enterprises may implicitly rely on the same infrastructure even if they outsource their DNS service to multiple DNS providers. In summary, our key contributions are as follows:  
* We propose a novel and lightweight resolver pool measurement approach based on NS chain reflecting, which is capable of discovering the implicit resolver pool structure of the DNS service in a fast and low-cost manner. * We conducted a comprehensive quantitative analysis of DNS centrality from the client-side and server-side in terms of the infrastructure on various dimensions, including IP address, domain name, DNS service provider, and IP provider, providing a multi-faceted view of DNS infrastructure centralization. * We uncovered several previously unknown insights about the centrality of DNS infrastructure. On the client side, more than 90% of FDNSes are actually backed by less than 5% of iRDNSes. On the server side, more than 98% of all domain names rely on a single name server provider, with the top 10 leading name server providers serving 48.5% of all domain names. The remainder of this paper is organized as follows. Section 2 introduces related work and Section 3 discusses the basic concepts of DNS. Section 4 describes our methodology to measure the centrality of DNS infrastructure. In Section 5, we measure the centrality of the client-side DNS infrastructure, and we analyze the centrality of the server-side DNS infrastructure in Section 6. Finally, we conclude the paper in Section 7.
# Influence of Altitude on Phytochemical Composition of Hemp Inflorescence: A Metabolomic Approach
## 2 Results and Discussion  
Multi-targeted applications of industrial hemp with the environmental benefits related to its cultivation, have raised interest in its production. Special attention has been paid to _C. sativa_ infloresances that represent a promising added-value product with remarkable pharmacological and nutraceuticalal effects [13; 16; 22; 23]. The phytochemical composition of infloresances has been studied intensively, but there is not substantial information that regards the differences that may rise due to geographical/microclimate factors. In this experiment, raw infloresances material obtained from plants cultivated in the Italian Alps at two different elevations was evaluated. Mountain (M) region was located in the commonality of Alagna Valsesia (1200 m ASL), whereas plains (P) cultivation was performed in the Province of Vercelli (130 m ASL).
## 3 Findings
### Feedback on App Usability and Workflow Modifications
#### 3.3.6 Suggestions for Improvement  
After analyzing the content of interviews, it was evident that the field workers completely understood the app workflow and appreciated the benefits of using ODK Scan in improving their work efficiency and performance. Moreover, field workers were eager to continue application use. In addition to simple aggregation reports, field workers wanted to enhance the features of the application. For instance, they suggested including a bookmark feature to tag any patient record, if he/she is not accessible via telephone at the first attempt. With the number of the records available in a table on the user's device, the most popular requirement was the patient look-up feature. As TB treatment involves multiple visits of the same patient for medical checkup, it is becoming increasingly difficult for field workers to retrieve a relevant patient's record from the ODK Tables default interface upon patient's revisit. A look-up feature will help field workers to avoid re-scanning and re-verifying forms, and the follow up service will be updated in an existing patient's record.  
Figure 7: Process of Follow up Visit Report (**left** to **right**).  
Currently, synchronization involves the movement of data in either direction. This means new records on the device are sent to the server and at the same time new records available at the server, synced by others, are downloaded onto the user's device. Deleting a record, either deliberately or mistakenly, is a potential threat of data loss. Therefore, defining user permission attributes to restrict data access to only the appropriate individuals would improve the Scan workflow. Lastly, one of the field workers suggested that instead of scanning, a direct-to-digital solution seems more feasible.
# Multiuser Equalizer for Hybrid Massive MIMO mmWave CE-OFDM Systems
### Notations  
Capital boldface letters denote matrices, and lower boldface letters denote column vectors. The operators \(\text{tr}(.)\), \((.)^{*}\), \((.)^{T}\), \((.)^{H}\), and \(\|.\|_{\text{F}}\) are the trace, the conjugate, the transpose, the Hermitian, and the Frobenius norm of a matrix, respectively. \(\{\alpha_{k}\}_{k=1}^{S}\) represents a \(S\)-length sequence. The operator \(\text{diag}(\mathbf{a})\) is the diagonal matrix, where the diagonal entries are equal to vector \(\mathbf{a}\), while \(\text{diag}(\mathbf{A})\) is a vector equal the diagonal entries of the matrix \(\mathbf{A}\). \(\mathbf{A}(n,m)\) represents the element of the \(n\)th row and \(m\)th column of \(\mathbf{A}\), while \(\left[\mathbf{B}\right]_{n,n}\) represents the \(n\)th element of diagonal of the square matrix \(\mathbf{B}\). The identity matrix of size \(N\times N\) is denoted by \(\mathbf{I}_{N}\), while \(\mathbf{e}_{u}\in\mathbb{C}^{U}\) is a \(U\)-length vector of zeros with the \(u\)th entry equal to one. The operator \(\arg(c)\) gives the phase of \(c\). Finally, the indexes \(t\), \(k\) and \(u\) represent the time, subcarrier and user terminal indexes, respectively.
# Two-Degrees-of-Freedom (2 DOF) Magnetic Spring-Based Electromagnetic Energy Harvester
## 1 Introduction
The simplest form of a 2 DOF system has two floating magnets and two fixed magnets. [PERSON] et al. proposed a two-degrees-of-freedom (2 DOF) electromagnetic energy harvester (EMEH) using a magnetically levitating 1 DOF oscillator system in a cylindrical housing to harvest energy from human body motion [18]. The theoretical model of the 2 DOF EMEH was validated experimentally. The experimental results showed that the performance of the 2 DOF system is much better than that of the 1 DOF system-based energy harvester. However, the magnetic restoring, linear and nonlinear coefficient, and system dynamics were not studied. Moreover, 2 DOF magnetic spring-based electromagnetic energy harvesters have been studied numerically and experimentally [19]. The proposed model consisted of two floating magnets and a bottom fixed magnet. The model did not have any top fixed magnet; therefore, the top floating magnet can oscillate with low frequencies. The proposed system has two resonance frequencies tuned to two fundamental frequencies. The proposed model was studied numerically and experimentally for vehicle monitoring, particularly railway monitoring applications. The findings showed that the 2 DOF system improved performance by 10% compared with the 1 DOF configuration. From the literature, it has been seen that some research works have been conducted based on 2 DOF magnetic spring-based electromagnetic generator systems [18; 19; 20]. However, no single paper in the literature has validated the theoretical model with the experimental model of the 2 DOF magnetic-based electromagnetic generator systems. The dynamics of the proposed linear generator system are very important for deeply understanding and developing electromagnetic generator systems. Therefore, this paper aims to investigate the dynamics of a 2 DOF magnetic spring-based generator system analytically and experimentally and the power generation capabilities of the electromagnetic generator system. This paper deals with the architecture of the 2 DOF magnetic spring-based linear generator system, analytical modelling, the system's behavior in relation to various design criteria, and an experimental analysis of the proposed linear generator system.
# Joint Maintenance Strategy Optimization for Railway
## 5 Conclusions  
In this paper, a maintenance strategy that combines periodic and preventive maintenance is developed by analyzing the characteristics and correlation of wheel flange and wheel diameter wear. Starting from the failure mechanism of the wheel wear and based on the cumulative shock model, a deterioration model of wheel flanges and diameters are established using the compound Poisson process. The Weibull distribution is used to describe the failure probability of the tread surface. The wear of the wheel flange, wheel diameter and tread surface failures are considered comprehensively. After that, the maintenance strategy optimization model is established to minimize the cost rate, taking the wheel flange thickness over the limit as the risk failure constraint. Finally, the validity of the model is verified by a numerical analysis. The results show that the proposed strategy can prolong the life of the wheelset and can reduce the maintenance cost rate, and it can ensure that the wheel flange thickness is kept in a safe state. The wheel does not need to be reprofiled frequently, improving maintenance efficiency. It has both practical application value and also economic significance for the maintenance work of railway vehicles.  
The developed maintenance strategy provides an alternative for the practical maintenance of railway bogie wheelsets. However, further expansion of this work can be conducted. In this paper, parameters such as the \(Sh\) and \(Qr\) values of the wheelset are not considered. In line with the actual situation of wheelset maintenance, future research can consider flange height and \(Qr\) value to develop maintenance strategy optimizations. This paper only studies the maintenance strategy of one wheelset, and the constraints on the wheel diameter and the difference between wheels on the same axle, bogie or rolling stock can also be further explored. Furthermore, it does not consider the internal degradation of the wheelset. Wheelset maintenance optimization for competitive failures can be further investigated.  
Conceptualization, H.Z. and X.W.; methodology, H.Z. and X.W.; software, H.Z.; validation, H.Z. and X.W.; formal analysis, H.Z., X.W. and Q.G.; investigation, H.Z., X.W., Q.G. and W.Z.; resources, H.Z., X.W. and W.Z.; writing--original draft preparation, H.Z.; writing--review and editing, H.Z., X.W., Q.G. and W.Z. All authors have read and agreed to the published version of the manuscript.  
This work is supported by the National Key R&D Program of China (Contract No.2020 YFB1600704).  
Not applicable.  
The authors declare no conflict of interest.  
Figure 15: Numerical comparison chart of wheel flange thickness deterioration.
# Novel Internet of Things Platform for In-Building Power Quality Submetering
###### Abstract  
As the number of facilities adopting a Building Management System under the Industry 4.0 paradigm increases, it is critical to ensure the good health of their operations. Business continuity and uninterrupted operations are key requirements for any building, for which Power Quality and Supply Reliability sophisticated monitoring can play an extremely important role. Submetering, as opposed to bulk-metering, implies measuring power consumption for individual units or appliances in a building complex. An Internet of Things mesh network, which brings ubiquitous power quality submetering inside the entire facility, would be extremely beneficial for the management of the building thus ensuring seamless business operations. This work describes a novel low-cost Internet of Things sensor for measuring and analyzing power quality at the input of any individual Alternating Current (AC) appliance, providing an early detection and analysis system which controls those critical variables inside the facility and leads to anticipate faults with early-stage alerts based on on-time data streams treatment. Moreover, the recorded power quality parameters that are processed in the Cloud system can help to reduce energy consumption, as power quality disturbances can be automatically analyzed and even compared to standard values. The proposed Internet of Things sensor will help users to detect most power quality steady-state and events disturbances, while monitoring the energy consumption. This Internet of Things Power Quality sensor is built around a flexible microcontroller, which manages an energy metering Integrated Circuit (IC) through Serial Peripheral Interface (SPI), increasing its original capabilities by including new sophisticated software functionality. Additionally, it wirelessly communicates with a cloud-based Internet of Things Platform to allow the storage and supervision of the different power quality events for the entire facility. An example of the access to the data is also included.  
advanced metering infrastructure; building energy management system; internet of things; power quality; smart grid +
Footnote †: journal: Applied Soft 2018
## 1 Introduction
However, when the system only bears a Gaussian variable or pure Brownian noise, the Hurst exponent [26] can be applied as the analytical standard for distinguishing the Gaussian variable, white Gaussian noise and long-range dependence automatically [27]. To this end, the application fields of the SSA method have been significantly expanded. In this paper, we apply a filter based on the basic SSA method and the Hurst exponent to reduce the femtosecond laser absolute distance measurement uncertainty automatically in the case of a wide range of absolute distance changes with a series of speeds. Both numerical simulation and an absolute ranging experiment based on a pair of free-running femtosecond lasers show that the basic SSA filter is capable of retrieving a moving target trajectory from the measurement data that is degraded by noise. The distance measurement uncertainty after filtering reaches 110 nm at a 200-Hz update rate. This method shows great potential to extend the femtosecond laser ranging technique to a wide range of LiDAR and dynamic measurement applications.