esa-sceva/satcom-chunk-collection huggingface dataset:
## 2 Problems with CSI Feedback and Overview of IBF  
### Problems with CSI Feedback  
Figure 1 shows the frame format for a MU-MIMO system with CSI feedback. To initiate MU-MIMO transmission in the downlink channel, period A is required as a negotiation time for user selection. As shown in Figure 1, the CSI is estimated at the UTs using the information in period B, and the estimated CSI must be returned to the BS within period C. When considering the MU-MIMO system, the number of transmit antennas \(N_{T}\) should be greater than or equal to the number of receive antennas multiplied by the number of users, that is, \(N_{R}\times N_{U}\). Therefore, period B incurs a large overhead. Although user scheduling is effective in the context of MU-MIMO transmission, as discussed in the previous section, period C incurs a very large overhead when user scheduling is considered. The influence of this CSI feedback overhead is discussed in Section 5.  
Figure 1: Frame format for multi-user multiple-input multiple-output (MU-MIMO) transmission with channel state information (CSI) feedback.
## 3 Improved CKF Localization Algorithm Based on Volume Criterion
### SVD Method Decomposes Estimated Covariance Array  
The volume criterion is used to pass a series of point sets with a nonlinear function and then approximate the posterior mean and variance of the nonlinear function based on the weighted summation [22]. When the standard CKF algorithm is used to calculate the volume points, Cholesky matrix decomposition is usually used to solve the estimated covariance matrix \(\mathbf{P}_{k-1|k-1},\mathbf{P}_{k|k-1}\). After several filters, the estimated covariance matrix in the algorithm easily loses the positive characterization. When the system covariance matrix is affected by the complex environment to form a pathological matrix, the CKF algorithm cannot decompose the covariance matrix via Cholesky decomposition, which leads to the failure of the whole filtering algorithm. In this study, SVD decomposition is used to decompose and estimate the covariance matrix based on the CKF algorithm. Its estimation accuracy is improved by up to 37.4% over three degrees of freedom compared with Cholesky decomposition [23]. In numerical matrix decomposition, the SVD method reduces the dimensionality by retaining only the most important singular values and vectors and estimates the pure signal by removing the noisy signal vector components that fall in the noise space. Therefore, the SVD decomposition method can improve the robustness of numerical computation and enhance the stability of the CKF algorithm.
# Classification Models for Nitrogen Concentration in Hop Leaves Using Digital Image Processing
## 2 Materials and Methods  
### Location of the Experiment  
Hop plants of the Cascade variety were cultivated in a protected environment (greenhouse) belonging to the LUPAM group (Hops, Research, Applications, and Management), located in the experimental area of the School of Agricultural Sciences (FCA) of Sao Paulo State University (UNESP \"[PERSON] de Mesquita Filho\") in Botucatu, Sao Paulo, Brazil.  
The greenhouse is located at 22\({}^{\circ}\)51\({}^{\prime}\) south latitude, 48\({}^{\circ}\)26\({}^{\prime}\) west longitude, and 786 m altitude. It measures 24 \(\times\) 7 \(\times\) 2.5 m and is constructed with an arched metal frame. The roof is made of transparent low-density polyethylene with a diffuser (100 mm thick) and the sides are closed with an anti-snake mesh. The climate of the municipality of Botucatu according to the Koppen classification is Aw, with hot, humid summers and cold, dry winters [24].
## 3 Results and Discussion  
### HPLC Profile of Orange Extracts from Waste Orange Peels  
The average retention times for hesperidin, neo-hesperidin, and naringin were identified as 31.98 min, 35.01 min, and 29.55 min, respectively. Figure 1 displays the representative HPLC profiles of hesperidin [Figure 1a] and orange extracts from waste orange peels [Figure 1b]. The result indicates that the main composition of orange extracts was hesperidin, which agrees with the observations of [PERSON] [40] and [PERSON] et al. [31; 38]. The investigated ranges for the determination of all analytes exhibited good linearity in the calibration curves, with R\({}^{2}\) > 0.9999. The hesperidin content in orange extracts was calculated to be 46.82 \(\pm\) 5.23 \(\mathrm{\SIUnitSymbolMicro g}\)/40 g dried orange. The dried navel orange peels extracted by 70% ethanol solution with successive extraction with ethyl acetate were investigated [41]. Hesperidin content was reported to be 31.45 \(\pm\) 0.38 \(\mathrm{\SIUnitSymbolMicro g}\)/dry weight of extracts [41]. The orange extracts were also detected by terahertz spectroscopy (THz), and their THz spectra were similar to those of the hesperidin standard [31], which is consistent with current observation where the main component of orange extracts was identified to be the hesperidin. Hesperidin was reported to be 100% detected in the sweet orange, whereas only a 20% probability of naringin can be found in the sweet orange [38]. For neo-hesperidin, it is not detected in sweet orange peels [38].  
Figure 1: HPLC profile of representative standard hesperidin (**a**) and orange extracts (**b**). **Note:** The \(x\)-axis is retention time (min) and the \(y\)-axis is milli-absorbance (mAU). The numbers beside the absorbance are the retention times.
## 5 Conclusions  
In this study, we characterized the viability of two lubricant additives, nano-graphene platelets and a phosphonium-phosphate-based ionic liquid, in rotorcraft gearbox oil for improving the scuffing resistance of gear steels under starved, loss of lubricated conditions. The experiments showed initial promise of the additives in increasing time to scuffing and even exhibited a synergistic effect when mixed together. This increase was higher for the two additives than the sum of the parts. The additives continue to be compatible at higher ionic liquid concentration when evaluating loss-of-lubrication performance. However, when evaluating the scuffing load, it was found that the additives, which individually outperformed the baseline oil, were a detriment when mixed together. In addition, the experiments suggest the additives have a complicated effect on the friction and run-in of the steels, dependent on the contact conditions.  
Overall, an increase in the time before initiation of scuffing in high-speed mechanical contacts when the oil is removed will aid in extending the operation of a rotorcraft gearbox during a loss of lubrication. However, the capacity of the contact to carry a significant load is also important to the properties of an oil for rotorcraft transmissions and is one of the metrics that an oil passing the DOD-PRF-85734 standard must meet. This initial look at the additives appears promising, but further studies are needed to optimize the additive concentrations for better compatibility across a wider range of conditions, and to see if the decrease in load capacity general occurs. Further, studies of the tribofilms on the surfaces may reveal the effect that the IL is having on the run-in process, and the interplay between the IL and NG during both starved lubrication and under increased loads.  
Conceptualization, A.K.R.; methodology, N.M, A.K.R. and S.B; formal analysis, N.M.; investigation, N.M. and A.K.R.; resources, A.K.R. and S.B.; writing--original draft preparation, N.M; writing--review and editing, N.M, A.K.R. and S.B; project administration, S.B; funding acquisition, A.K.R. All authors have read and agreed to the published version of the manuscript.  
This research was funded by U.S. Army, grant number W911 QX-13-C-0174.  
The authors are grateful to [PERSON] of Covalent Associates, Inc. for many fruitful discussions on ionic liquids. The authors would like to acknowledge the guidance and encouragement from [PERSON] during the course of this work.
# A Nonlinear Convolutional Neural Network-Based Equalizer for Holographic Data Storage Systems
## 3 Proposed Model  
### Channel Modeling  
In this study, we model the HDS channel as in [14], where user signal \(u[k]\) is modulated and stored in the HDS channel as a 2D data page \(s[j,k]\). Readback signal \(r[j,k]\) is then collected and distorted by the 2D ISI and electric noise using the following equation:  
\[r[j,k]=s[j,k]\otimes\mathbf{H}+w[j,k] \tag{11}\]  
where \(\otimes\) is the 2D convolution operator. \(\mathbf{H}\) is a \(3\times 3\) matrix representing the channel impulse response of the HDS system. \(w[j,k]\) represents the white noise with the Gaussian distribution (mean zero and variance \(\sigma_{w}^{2}\)). In addition, we define the SNR as follows:  
\[SNR=10\log_{10}\left(\frac{1}{\sigma_{w}^{2}}\right) \tag{12}\]  
To obtain the parameters of \(\mathbf{H}\) in the simulation, they are calculated from the continuous PSF as follows:  
\[h_{n,m}=\int\limits_{n-1/2}^{n+1/2}\int\limits_{m-1/2}^{m+1/2}h(x,y)dxdy \tag{13}\]  
Here,  
\[h(x,y)=\frac{1}{\sigma_{b}^{2}}\sin c^{2}\left(\frac{x-m_{x}}{\sigma_{b}}, \frac{y-m_{y}}{\sigma_{b}}\right) \tag{14}\]  
Here, \(\text{sinc}(x,y)=(\sin(\tau\text{x})/\tau\text{x})(\sin(\tau y)/\tau\text{y})\); \(m_{x}\) denotes the misalignment in the horizontal direction; \(m_{y}\) denotes the misalignment in the vertical direction; and \(\sigma_{b}\) denotes the blur grade. Channel matrix \(\mathbf{H}\) has the following form:  
\[\mathbf{H}=\begin{bmatrix}h_{-1,-1}&h_{-1,0}&h_{-1,1}\\ h_{0,-1}&h_{0,0}&h_{0,1}\\ h_{1,-1}&h_{1,0}&h_{1,1}\end{bmatrix} \tag{15}\]
## 3 The Proposed SensorAnt Protocol
### SensorAnt Description
#### 3.6.4 Path Recovery Steps  
In this proposed method, when the source transmits data to the sink within a period of this session it will start sending Ant-F to explore and update the information about the current routes used and check for any other better routes using a proactive mechanism. This process periodically checks the changes in the WSN caused by link failured, either by movement of the sensor nodes or the depletion of sensor nodes in the available path. This process involves the same concept of path searching. It updates the pheromone information to guide the ants to track new routes for data transmission by spreading the pheromone value using the dissemination message, to its neighbors and checking the energy level to compute path quality function of alternative routes. Figure 5 described the structure of the dissemination message where the pointer field indicates if the pheromone value is real or non-real. The non-real pheromone, is obtained by reinforcement learning scheme to update the pheromone table, replacing the maximum (best) value of the pheromone trace based on the multi-criteria function qualities, of both path and hop, which frequently monitor the energy level of the sensors in relaying the data. The advantages is that, this strategy will avoid routing the data packet using the same path all the time and prevent the sensor node from being drained very quickly, resulting in prolonged network life time. This mechanism hence increases the chances of selecting a better route between multiple paths available to forward packets to the sink.  
Figure 5: The dissemination message scheme.
# All About Audio Equalization: Solutions and Frontiers
## 4 Graphic Equalizers
### FIR Graphic Equalizers  
FIR-type graphic equalizers have been developed since the early years of digital equalizers [72; 73; 74; 75]. An advantage of FIR filters here is the possibility to realize a linear phase response, causing no phase distortion and thus largely retaining the waveform of the signal [73; 76]. However, many audio engineers doubt whether linear phase filters are a good choice for audio signal processing, as they may lead to pre-echos or ringing of transients [77; 78; 76]. Furthermore, just like in the case of tone controls, linear phase filters produce more delay than minimum phase filters, which may be noticeable in live sound reproduction. Nevertheless, it is also possible to convert an FIR filter to be minimum phase, which reduces the delay [79].  
For FIR graphic equalizers, there are two basic implementation strategies to choose from: a single high order FIR filter and a parallel structure. These choices are different from those used in the IIR case, mainly because the cascade structure is pointless in the case of standard FIR filters: cascading several low order FIR filters leads to a less powerful system than a single high order filter with the same number of coefficients.  
In principle, a single high order FIR filter could approximate the frequency response specification dictated by the command gains of a graphic equalizer [75; 77]. However, as the command points are usually located logarithmically in frequency, it will be necessary to use interpolation to obtain a smooth target response [70; 75; 79; 80]. Still, a fundamental problem remains: the order of the FIR filter must be large, at least several thousand, to approximate well the desired magnitude response at the lowest band [75; 77; 79]. That is clearly more costly than using a biquad IIR filter per band. To reduce the computational cost of long FIR equalizing filters at low frequencies, [PERSON] _et al._ have suggested a multirate system in which downsampled filters running at a low rate improve the approximation performed by a fullband filter running at the audio sample rate [75]. [PERSON] describes in his patent how a graphic equalizer can be implemented using a frequency-warped FIR filter [81].
# Enhanced Fall Detection Using YOLOv7-W6-Pose for Real-Time Elderly Monitoring
## 3 Materials and Methods
### Materials  
The primary hardware was the INSTA360 GO3, 64 GB, Wi-Fi camera, chosen for its affordability, ease of use, and advanced safety monitoring features. It records in up to 2.7K resolution, providing clear, stable images even during motion, and syncs easily with an app for real-time video streaming and analysis.  
The system was implemented in Python, utilizing several key libraries:  
* OpenCV for video capture and image processing [52].
* PyTorch for machine learning, enabling real-time applications [53].
* Torchvision for datasets and image transformations [54].
* NumPy for handling multi-dimensional arrays and mathematical operations [55].  
For our research, we used a GPU with the following characteristics: nVidia GeForce RTX 4070, 12 GB, GDDR6. This parallelism allows the YOLOv7 model to process video frames quickly and accurately, ensuring immediate responses to potential falls. The integration of CUDA Python with the system enabled us to achieve the necessary performance levels to meet the real-time requirements of our application.  
For detecting and estimating human body key points such as shoulders, elbows, knees, and feet, we utilized YOLOv7-W6-Pose. YOLOv7-W6-Pose is specifically designed to integrate these two tasks, allowing for efficient analysis of human posture in real-time applications.  
The model setup and training process were performed according to the documentation available in the official YOLOv7 repository. The model's ability to accurately predict these key points is important for fall detection applications.  
We sourced pre-trained models directly from the official YOLOv7 repository on GitHub [56], which provides access to various versions optimized for different scenarios. YOLOv7-W6-Pose allows us to achieve simultaneous person detection and key point estimation, which is essential for our fall detection application.
# Phase-Coded and Noise-Based Brillouin Optical Correlation-Domain Analysis
## 2 Phase-Coded Brillouin Optical Correlation-Domain Analysis
### The Overlay of Pump Pulses
**(a)** Calculated normalized magnitude of the stimulated acoustic wave density fluctuations as a function of time and position along 6 m of fiber. Both pump and signal waves are co-modulated by a perfect Golomb phase code that is 127 bits long with a symbol duration of 200 ps. The pump wave is further modulated by a single amplitude pulse of 26 ns duration. The acoustic wave is confined to discrete and periodic narrow correlation peaks. Acoustic waves at peak locations are stimulated sequentially, one after another, with no temporal overlap. Reproduced with permission from [22], Optical Society of America, 2014. **(b)** Measured normalized Brillouin gain as a function of correlation peak position and frequency offset between the pump and signal waves. The fiber under test was over 1600 m long. Phase-coded B-OCDA with an overlaid pump pulse was performed with a spatial resolution of 2 cm. All 80,000 resolution points were successfully addressed. The gain map shows a magnified view of 3 m towards the far end of the fiber, containing a few-centimeters-long hot spot. The heated region is clearly identified in the measurements. Reproduced with permission from [42], SPIE, 2014. \(2\tau/T_{p}\), an improvement of 2 orders of magnitude compared to that of Equation (5). The OSNR no longer degrades with the measurement range. In a more recent example, phase-coded B-OCDA with a pulsed pump was successfully demonstrated over 17.5 km of fiber with a spatial resolution of 8.3 mm (see Figure 5, [20; 43]). The number of potential resolution points, over 2 million, is arguably the largest such set among all Brillouin sensors reported to date [20; 43]. This milestone result highlights the importance and potential of bringing together correlation-domain and time-domain analysis principles. It should be noted that similar pulse-amplitude modulation of the pump wave was also successfully introduced to frequency-modulation-based B-OCDA [44].
# Mapping with Pleiades--End-to-End Workflow
## 2 Related Work  
The proposed end-to-end workflow for 3D mapping with VHR Pleiades satellite stereo imagery touches various scientific independent topics that are reviewed in this section. Due to the goal of end-to-end mapping, those topics are intertwined like pieces of a puzzle, together bringing the complete processing chain into being. The presented topics are multidisciplinary and touch the fields of remote sensing, photogrammetry, computer vision and applied mathematics. This section follows the structure as given in Figure 1, thus touching the four core tasks of model adjustment, DSM generation, DTM generation and ortho-rectification, including all required sub-tasks.
## 1 Introduction
This study assessed the performance of a compact unit for OWTS consisting of a stacked vertical flow filter unit (VFF) and horizontal flow filter unit (HFF), both packed with biochar as the filter medium, in removal of organic matter, nitrogen and pathogens from household wastewater. Specific objectives of the work were to: (i) assess the progress of organic matter degradation, nitrification and denitrification in the combined VFF-HFF biochar filters over an operating period of 126 weeks, (ii) determine the effects of hydraulic loading rate (HLR) on nitrification, denitrification and removal of _Escherichia coli_ and _Salmonella_ spp. and (iii) assess the long-term removal of organic matter, nitrogen and pathogens. The principles of the VFF-HFF biochar filter design are that (1) the large specific surface and high porosity of the biochar and the unsaturated flow mode in the VFF provide a suitable environment for development of aerobic biofilm, where biodegradation of organic matter and nitrification occur; and (2) the saturated flow mode and limited oxygen access in the HFF provide an anoxic environment for denitrification, while the large micropore space in the biochar hosts anoxic microzones to sustain denitrification.
## 5 Category I: Energy Transaction
### Transaction Settlement Method
#### 5.3.3 Market Transaction Model  
Three market transaction models are studied in [111, 112]. First, the market is cleared the day before it operates [113]. The products considered in the proposed day ahead market are energy and flexibility. The next day's hourly clear of demand and supply generates 24 market prices and quantities. The supply and demand participants are matched before the payment is executed. If the supply and demand do not match, a distributed flexible load is allocated to cover an inflexible supply. The load owners need to set a price and the cheapest loads will be to cover the inflexible supply. If there is still a mismatch between supply and demand after the allocation, the rest will be traded in the wholesale market. Similar ideas are applied in [9]; the gap between the market and renewable energy pricing is explored firstly, and then an hourly alternative energy pricing scheme is proposed that would help expand renewable energy production while reducing the carbon footprint. One of the projects that has been done so far is an international project called SolarCoin, which advocates that all solar manufacturers, for every kilowatt-hour of energy they produce and put into the grid, get a SolarCoin to drive renewable energy generation [70]. In another project in Belgium, the idea behind NRGcoin is to compensate for inadequate subsidies for renewable energy and encourage citizens to use local renewable energy by paying them in a cryptocurrency called NRGcoin [73]. It is a virtual currency that can be redeemed with a legal tender (the euro).  
Real time trading is performed to conduct market clearing at the same time, or close to, as operation [111; 113; 114]. It generally has a certain frequency. periodically, the node sends the predicted deviation to the market and eliminates it by trading energy. In contrast to the previous settlement model, it uses a flexible payload to correct bid bias. If the flexible load in the system can successfully eliminate deviations, then the market price will be the price of the last accepted flexible load.  
The final model is a system based on grid operators sending quotes and node responses. When the operator anticipates congestion, the node provides flexibility to reduce power at its own time stage, then the node sends the quantity and price it can offer, and the operator selects the tender that meets the requirements.