esa-sceva/satcom-chunk-collection huggingface dataset:
# Tunable Perforated Panel Sound Absorbers for Variable Acoustics Room Design
## 4 Results and Discussion
### Case Study: Application to Variable Acoustics Room Design
On the other hand, the RT is reduced at the frequency of maximum sound absorption of the corresponding tunable configuration, whereas the D50 and C80 increase, thus improving the clarity or intelligibility of speech as the energy of sound reflections is reduced. Specifically,  
Figure 5: Average results of the case study room simulated using the ray tracing method for each of the five configurations of variable solution TS-A and different occupancy levels: (**a**) Reverberation Time, RT; (**b**) Definition, D50; and (**c**) Clarity, C80 (**top**: empty room; **center**: one-third occupation; and **bottom**: full occupation). Gray shade indicates frequencies outside the domain of validity. a shift of two octave bands from 1000 Hz to 250 Hz can be achieved by using the proposed tunable solution. Analyzing the results in more detail, when no occupants are inside the room, activating more absorbent solutions helps to decrease the global reverberation and increase the Definition (D50) and Clarity (C80). It is particularly interesting to note that configuration A#1, which has a lower perforation rate but exhibits a low resonant frequency, allows the good control of the reverberation and of the quality parameters (D50 and C80) throughout the analyzed frequency range. In the opposite case, when a full room is assumed, opting for solutions with higher absorption coefficients may induce an excessively \"dry\" acoustic environment, with reverberation times below 0.7 s, if the A#1 solution is used; thus, for such a case, the A#1 configuration or even a solution with all perforations closed (reflective) could be used for the better control of the room's acoustic environment. Observing the results for the one-third occupation configuration, a very similar trend can be seen, although with a less pronounced decrease in reverberation with the different solutions. It should also be noted that, besides the cases studied here, in which the configuration is homogeneous throughout the treated surfaces, other possible combinations could be used (for example half of the area with A#1 and the remaining half with A#4), allowing us to adapt the room's behavior to reach intermediate values between the reference (all rigid surfaces) value and the values obtained for the three parameters with the A#1-A#5 configurations. The use of such combinations could even allow us to control and adjust the acoustic behavior of the space so that it remains approximately constant, independent of the room's occupation. An example of an architectural approach developed to provide good speech intelligibility by optimizing the dimensions and positions of the acoustic treatments for different audiences can be found in [30].
# One-Step Synthesis of Bunsenite Cadmium Oxide Nanoparticles
## 3 Results  
### Formation of Bunsenite Cadmium Oxide NPs  
The interaction of the capping agent (PVP) with the Ni\({}^{2+}\) and Cd\({}^{2+}\) ions is depicted in Figure 1, which is held together by the strong ionic interactions generated between the metallic ions and the polymer chain amide groups. Metallic salts have been observed to dissolve in the presence of amide groups in pyrrolone rings and methylene groups in polymers due to the constant advancement of electrostatic and steric stabilization while the sample is still in the solution stage. The metallic ions are frequently enclosed by shorter polymer chains after surface absorption [30; 31; 41; 42; 43], which probably arose initially due to some degree of crumbling in the PVP stabilizer. Short polymer chain capping allowed for the homogeneous scattering of metallic ions in the material's vacant spaces and networks. Furthermore, the calcination procedure, which oxidized Ni\({}^{2+}\) and Cd\({}^{2+}\) ions, led to the formation of bunsenite cadmium oxide nanoparticles. A solid-state interaction between NiO and CdO was initiated at high temperatures during the beginning of the metal phase growth, resulting in binary nanoparticles. During this step, organic components were removed, and the nanoparticles began to combine as a result of the action of higher calcination temperatures. Organic compound-containing gases, such as NO, N\({}_{2}\), CO, or CO\({}_{2}\), disintegrated during the subsequent calcining process. Furthermore, the other organic components were removed during the calcination stage, and the increased temperature causes fusion among the nanoparticles, increasing particle size while obtaining the lowest surface energy. The use of PVP has a purpose that extends beyond the solution and drying stages, as the nucleation of bunsenite cadmium oxide nanoparticles is stimulated throughout the calcination process. The formation of smaller nanoparticles was decreased due to the high molecular weight and the creation of repulsive forces by the polyvinyl groups. As a result, particles grew larger with lower surface energy. The PVP addition had an effect that extended beyond the solution and drying stages, as evidenced by its ability to enhance bunsenite cadmium oxide nanoparticle nucleation throughout the calcination process. Smaller nanoparticles grouped to a lesser amount when PVP was absent due to their high molecular weight and the electrostatic repulsion created by polyvinyl groups [21; 44]. The capping agent action of PVP can have a considerable impact on the formation of bunsenite and cadmium oxide nanoparticles. PVP also regulates nanoparticle growth by capping them, decreasing the rate of accumulation, improving crystallinity, and assisting in the consistency of the prepared samples' characterization [41; 45].
## 4 Evaluation of Normalization Results
### Comparisons among Bands  
To compare evaluation methods among bands, scatter analysis was applied to the normalized subjects and reference images. The coefficient and bias of fitting equation results are shown in Figure 6; normalization is much more precise when the fitting coefficient is closer to 1 and the bias is closer to 0. Except for band 2 of point\(-\)multi, coefficients obtained from polygon\(-\)multi are much closer to 0, which means the reflectance of the two images has better radiometric consistency. The polygon\(-\)single method follows closely, and then, in order, SpecLib\(-\)single and SpecLib\(-\)multi that only consider bandwidth. The fitting coefficients are less than 1, which is counter to results from other methods. The bias results show that the polygon\(-\)single and polygon\(-\)multi methods are relatively more accurate for most bands. As indicated by R\({}^{2}\) and RMSE evaluation (Figure 7), polygon\(-\)multi has the best fit and point\(-\)multi the worst, indicating that the calibrated subject image has satisfactory radiometric consistency with the reference image.  
Figure 5: Statistical results by pseudo\(-\)invariant polygon features with single\(-\)band data.
## 3 Results and Discussion
### ROAV Analysis  
A total of 245 volatile compounds were identified by gas chromatography-mass spectrometry (GC-MS), and their ROAVs were determined. As shown in Table 2, a total of 34 aromatic compounds with ROAV \(\geq\)1 were identified across the four rose beverage samples. Among them, the UFR, SFR, LFR, and LSFR samples contained 27, 25, 29, and 32 compounds, respectively. Based on the ROAV values and the classification by [PERSON] et al. [80], the aromas were categorized into three groups: light (1 \(\leq\) ROAV \(<\) 10), medium (10 \(\leq\) ROAV \(<\) 100), and intensive (ROAV \(\geq\) 100). Intensive aromas included eugenol, D-ctronellol, linalool, citronellol, geraniol, phenylethyl alcohol, \(\beta\)-myrrene (7-methyl-3-methylenedcta-1,6-diene), 1-nonanol, 2,4-di-tert-butylphenol, 2-methoxy-2-methylbutane, isoamyl acetate, D-limonene ((4R)-4-isopropyl-1-methylcyclohexene), nonanal, 2-phenylethyll acetate, ethyl hexanoate, 2-(methylamino)benzoic acid methyl ester, \(\beta\)-phellandrene (1-methyl-4-(1-methylethenyl)cyclohexene), \(\beta\)-nerol ((ZZ)-3,7-dimethyla-2,6-dien-1-ol), 2-undecanol. Compounds such as methyl salicate, \(\alpha\)-Terpineo, methyleugenol, (Z)-3,7-Dimethyl-2,6-octadienyllethanoate, \(\alpha\)-phellandrene ((5S)-5-isopropyl-2-methylcyclohexa-1,3-diene), 2-nonanol, 1-decanol (decan-1-ol), 1-hexanol, benzaldehyde, and ethyl octanoate had medium aromas.  
A heatmap (Figure 5) was created to clearly show the contribution of volatile compounds with ROAV \(\geq\)1 in different rose beverages. In the LFR, the aroma contribution of compounds such as methyl salicylate (apple aroma), linaloalool (rose aroma), nonanal (floral aroma), citronellol (rose and fruits aroma), geraniol (rose aroma), and eugenol (cloves aroma) was significant. In the LSFR, the aroma contribution of compounds like 1-decanol (rose aroma), 2-phenylethyl acetate (rose and fruits aroma), \(\beta\)-nerol (rose and orange aroma) was notable. In the SFR, the aroma contribution of compounds including ethyl octanoate (pineapple aroma), ethyl hexanoate (fruity aroma), and isoamyl acetate (banana aroma) was evident. However, in the UFR, the aroma contribution of compounds such as (E)-\(\beta\)-ionone (sweet citrus aroma), benzaldehyde (nut aroma), and nonanal (rose and orange aroma) were pronounced.  
Figure 4: Heatmap and cluster analysis of aroma compounds in four rose beverage samples (\(n=4\)). (**A**) Alcohol compounds; (**B**) Terpene compounds; (**C**) Ester compounds; (**D**) Aldehyde compounds; (**E**) Ketone compounds; (**F**) Acid compounds; (**G**) Phenol compounds. UFR: rose beverage without fermentation; LFR: rose beverage fermentation by \(L\). _plantarum_; SFR: rose beverage fermentation by \(S\). _cerevisiae_; LSFR: rose beverage fermentation by \(L\). _plantarum_ and \(S\). _cerevisiae_ collectively.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Compounds** & **CAS** & **Odor Description** & **Threshold (mg/kg)** & \multicolumn{2}{c}{**OAV**} \\ \cline{2-7}  & & & & **LSFR** & **LFR** & **SFR** & **UFR** \\ \hline
4–Allyl\(-2\)–MeMeMeMeMeMeMeMeMeMeMeMeMeMeMeMeMe
# Polarization Imaging Method for Underwater Low-Visibility Metal Target Using Focus Dividing Plane
## 4 Experimental Results and Analysis
### Polarization Imaging Experiment of Metal Target in Low-Visibility Underwater Scene  
The metal target detection experiment of the underwater low-visibility scene consists of the following parts. First, the bottom of the experimental water tank is covered with irregular sediment to simulate the real underwater background. The metal target is placed on the upper part of the sediment irregularly. Then, clean water is injected into the experimental water tank, and the water injection depth is about 30 cm. Above the water surface, a tripod is used to fix the polarization camera and the light source. Finally, by adjusting the focal length of the camera, the brightness of the light source and the rotation angle of the polarizer, the original polarization image of the metal target is collected by the upper computer software. The polarization information and image quality evaluation data are calculated by the processing module. This experiment uses different metal targets of silver, gold and black, as shown in Figure 11.  
Figure 11: Physical figure of metal target.  
Figure 10: Image DOP quality evaluation of different targets.  
The experimental results are shown in Figure 12, including the light intensity I and DOP images of three metal targets. It can be seen that the targets in the background can be easily recognized without image enhancement processing. Compared with the light intensity image, the contrast enhancement of the polarization image is significant, the texture details are rich and the contour features are significant. This is due to the polarization characteristics of the reflected light on the material surface. Sediment and other objects are depolarized due to multiple scattering due to surface roughness, while metal materials have good polarization retention and a high degree of polarization. Therefore, the degree of polarization image is suitable for the detection of metal targets in the underwater complex sediment background.  
The experimental image quality evaluation data are shown in Table 1. Among them, the values of EME, information entropy and average gradient of _DOP_ images of three kinds of metal targets are significantly higher than those of light intensity image I, further verify the effectiveness of using polarization imaging to detect metal targets in underwater low-visibility scenes.
# Visible Light Communication: A System Perspective--Overview and Challenges
## 3 Applications
### Entertainment and Advertisement Industry  
VLC requires line of sight (LoS) or semi line of sight. This can be used for applications requiring access to localise information. Theme parks, toy or advertisements are such applications, where the aim is to produce products with reducing costs. For example, most of the toys are battery powered and operates in LoS, and typically require a wireless connection to control the toy [51]. Some researchers have explored battery-free VLC communication system. [PERSON] et al. have developed a new VLC based communication, called passive VLC that uses the backscatter communication for battery-free IoT applications [52]. This system is based on RetroVLC which tackles the challenges of directional communication and low optical coupling (mostly less than 20% via solar panel) for wideband VLC. RetroVLC uses the concept of retroflecting which involves sending light back, almost, along with the incoming path, achieving a pointed communication. Miller codes are used to double bandwidth utilisation compared to Manchester coding. Trend-based modulation and code-assisted demodulation are proposed for reducing the modulation time. Two proof of concept systems are developed to validate their proposed scheme. A data rate of 1 Kbps was achieved with the RetroVLC system.  
A single LED light can be used for transmission and reception as well as providing the visualisation to entertain kids. This would save energy and cost, also not polluting the precious RF spectrum. Another use of VLC could be in the advertising industry, where large billboards made of LED's are used for advertisement. Such large billboards with high light intensity and equipped with hundreds of LED's can be used for providing free outdoor network connectivity that can work as hotspots for users, machines or smart cities applications.
## 4 Experimental Methods and Results
### Comparison Results between Difference Advanced Versions of EMD  
From the previous three experiments, the best architecture of the proposed model was PCA-EMD-LSTM. However, there are advanced versions of EMD such as EEMD and CEEMDAN. Therefore, this experiment changed the EMD part from the proposed model to both EEMD and CEEMDAN, called PCA-EEMD-LSTM and PCA-CEEMDAN-LSTM, respectively. To create the prediction model, closing price of the stock market in Thailand and principal components from PCA are used as input features.  
The experiment result shows in Table 10 that the PCA-EMD-LSTM had the lowest model performance and PCA-EEMD-LSTM had a moderate model performance. On the other hand, using the EMD as a decomposition method is the most effective for prediction with PCA-LSTM. Finally, the PCA-EMD-LSTM architecture had the highest model performance and Figure 3 can exclude the news sentiment score part with blue background.
## 3 Materials and Methods
### Raw Material and Sample Preparation  
Whole salmon fish (_Salmo salar_) from Norwegian aquaculture were purchased in a local market in Valencia (Spain) during different weeks of June 2019. They were immediately transported to the laboratories of the University of Valencia under refrigerated conditions. Individual salmon were dissected as a simulation of fish processing for human consumption. Then, muscle leftovers, complete heads, viscera, flesh-free skin, and tailfins were placed separately inside aluminum containers and frozen at \(-\)80 \({}^{\circ}\)C for 48 h. Next, they were freeze-dried (LABCONCO, 2.5. FREE ZONE, USA) for 72 h, and keep in a desiccator until reaching a constant weight. Then, water content was determined gravimetrically. The moisture percentages were 67.61% \(\pm\) 1.04%, 61.66% \(\pm\) 2.52%, 52.31% \(\pm\) 1.98%, 45.04% \(\pm\) 1.60%, and 45.63% \(\pm\) 0.71% for muscle remains, heads, viscera, skin, and tailfins, respectively. Similar values for salmon head, viscera, and skin were reported by [PERSON] et al. [6] and [PERSON] et al. [5]. Each type of sample was ground in an analytical mill (A11 basic IKA(r) WERKE, Staufen, Germany) and stored at \(-\)25 \({}^{\circ}\)C until the extraction process and the determination of possible food contaminants.
## 2 Research Object and Test Arrangement
### Vibration Inducement  
Five fundamental conditions (shutdown, power generation and phase control, the operation of power generation, pumped storage, and pumped phase control), along with twelve specific conditions, feature in the running process of a PSPS. The transitions between these conditions can result in increased vibrations within the power station structure. Theoretically, no vibrations occur in shutdown conditions; therefore, units 1#, 2#, 3#, 4#, and 5# in pumping conditions were compared with shutdown conditions.  
Before the test, this study primarily concentrated on the propagation of z-direction vibrations. The presence of horizontal vibrations was inconsequential. A portable vibration calibrator was utilized to calibrate the acceleration sensor to reduce the experimental error as much as possible. In the data analysis, the digital filter of Butterworth was utilized to filter the signal. The order of the filter was four, to maximize the fidelity of the detected signal. The critical frequency was 0.5. The filter utilized was a low-pass filter. And the measured data were processed using the detrend function to remove data trend items and reduce external ambient interference. Subsequently, the z-direction vibration acceleration spectrum maps and root mean of vibration were obtained for each measuring point, as shown in Figures 3 and 4. The specific working conditions are shown in Table 3. The power generation conditions required a power higher than 0 MW, and the pumping conditions required a power lower than 0 MW.  
Figure 3: The spectrum maps of shutdown conditions and five units in pumping conditions. (**a**) P1—upper reservoir; (**b**) P3—upper inclined shaft; (**c**) P8—horizontal flat tunnel; (**d**) P9—lower flat tunnel.  
The above results indicate that the amplitude of the z-direction vibration of each measuring point was negligible under shutdown conditions. The spectrum maps resemble white noise. Under pumping conditions, however, the amplitude of the z-direction vibration at each measuring point significantly increased compared with shutdown conditions. Moreover, a dominant frequency emerges near 70 Hz in the spectrum maps. This comparison proves that ambient vibration was generated during the operation of the units and had an impact on the ground. The subsequent analysis depended on this conclusion.  
As shown in Figure 4, the root-mean of vibration of each measuring point in the five units while running significantly changed compared with the shutdown conditions, proving the conclusion regarding the spectrum maps. Analyzing the shutdown condition revealed an ambient vibration of approximately 0.02 cm/s\({}^{2}\) in the whole division pipeline area, and this did not affect the daily lives of nearby residents.
# Experimental Study and Parameter Optimization of a Magnetic Coupled Piezoelectric Energy Harvester
## 2 Modeling and Analysis  
### Operation Principle  
The magnetic coupled piezoelectric energy harvester studied in this paper is shown in Figure 2 and some parameters are marked in the figure. The structure consists of one unimorph cantilever beam and one auxiliary beam without piezoelectric material. The cantilever beams are fixed on a base parallel and the auxiliary beam is set below. The ends of the two cantilever beams are attached with the same type of magnets, which are aligned to introduce a vertical nonlinear magnetic force on the tips.  
The resonance frequencies of the beams in the structure are different and determined by the material, size and mass parameters. In order to ensure the alignment of the magnets and facilitate the analysis, the length and width of the beams are the same and the frequency separation is performed by setting the mass and the height of the beams.
## 2 Connector Design
### PB Connector  
The PB connector allows a connection from the infusion and drainage bags of the PISA(r) system to the transfer line of the Baxter(r) system, favoring the exchange of peritoneal fluid necessary to carry out peritoneal dialysis treatment. This connector has essential characteristics in terms of its internal conduit and input and output connection. Additionally, the connector characteristics are divided into five main parts:  
1. An inlet flow connection for the PISA(r) bags system;
2. Circumference limitation to avoid contamination of the nozzle connection between devices;
3. A PB malleability connector;
4. A cylindrical body of the PB connector.
5. A flow outlet connection for the Baxter(r) transfer line.  
Additionally, the geometry and ornament have specific characteristics, which are described below:  
* For handling: special finger fasteners geometry with a chamfer and a 1 mm offset for handling with fingers;
* Internal duct reduction from 6.50 to 2.50 mm, through a chamfer of 2 mm with an inclination of 45\({}^{\circ}\);
* For the fingers: circular area with a diameter of 28 mm, a thickness of 2 mm, circular area at the top of 1 mm, and circular area at the bottom of 0.50 mm;
* A mechanical seal to avoid fluid leakage;
* A suitable thread geometry connection of peritoneal PISA(r) bags to the Baxter(r)'s transfer line.  
Figure 4 shows the technical drawing of the PB connector, shown in an isometric view and horizontal cross-section, as well as a description of its main parts.  
Figure 3: Isometric cross-section view of the BP connector.  
The BP and PB connectors are designed to establish a successful connection between the commercial Baxter(r) and PISA(r) systems to favor emergency patient care. Both connectors have a slot in which to place a hermetic mechanical seal (o-ring) and prevent the leakage of the dialysis solution to ensure the connection between devices is airtight during the peritoneal dialysis treatment. The connector's shape geometry allows the correct manipulation of the device to avoid contamination that could cause peritonitis. The material used for manufacturing the connectors for the experimental tests is titanium \"Ti-6 Al-4 VELI\", which is used in medical devices and for the CAPD procedure; it can also be subjected to the cleaning process for reuse in the same treatment.
## 2 Methodology
### Feature Extraction  
Statistical feature extraction plays a key role in distinguishing between normal and faulty states by numerically expressing various statistical properties of vibration signals [16]. Fault conditions in machinery often lead to changes in the statistical distribution of vibration signals, and utilizing representative statistical features can significantly enhance classification performance [17]. Due to their simplicity and clear interpretability, statistical features  
Figure 1: Denoising Autoencoder Structure.  
are widely adopted in vibration-based condition monitoring and fault prediction [16; 18]. In this study, five statistical features were used: mean, RMS, standard deviation, kurtosis, and skewness.