esa-sceva/satcom-chunk-collection huggingface dataset:
# A Survey on Physical Layer Techniques and Challenges in Underwater Communication Systems
## 1 Introduction
For simplicity, a calm sea surface has been chosen to acquire a stable channel impulse response (CIR). To design the UWA-based transmission system, many issues need careful and thorough investigation. A few of the encountered problems include [16]: (1) limitation in the distance of propagation for sound waves due to attenuation from the absorption of the UWA waves; (2) reduction in the speed of propagation of sound waves, i.e., approximately 1500 m/s; (3) interference and echoes generated due to multipath reflection from the top and bottom of the sea surface; (4) the transmitter and receiver motion inducing heterogeneous characteristics to the underwater transmitted signal as well as the Doppler's effect; (5) the ocean noises. Moreover, the impulsive noise adversely affects the noise due to the presence of Gaussian noise and the performance of the signal processors degrades [17; 18; 19]. The underwater channel properties are extremely variable and can be changed in both time and space. Fluctuations induced due to the environment include seasonal changes, the movement of the targets and the acoustic systems, internal waves, tides, currents, seabed relief, geographical salinity, temperature differences, etc. The above-mentioned characteristics make the UWA signal fluctuate randomly. As a result, both the error correction techniques and the selection of modulation technologies become more challenging. Multicarrier modulation in the UWA channel is used to alleviate the limitations of the bandwidth. The delays in a long-time UWA channel are overcome using this alternative approach. It decreases the ISI by increasing the symbol interval [20]. This paper delivers a summary of the important theoretical and practical advances in the UWAC field. Moreover, the modeling of underwater channels for the consequent duration is also discussed. Awareness is also provided into some of the open research challenges faced by researchers in this field to empower the subsequent generation of UWCs. An extensive review of all UWCs research is avoided by concentrating only on the technologies of acoustic modulation and modeling of the UWA channel. This paper reviews numerous characteristics of UWAC. Figure 1 depicts the outline of UWA physical layer technologies, channel problems, and challenges. For simplicity and ease for the reader, the abbreviations list is mentioned in Table 1. \begin{table}
\begin{tabular}{c c} \hline \hline
**Abbreviations** & **Full Forms** \\ \hline AI & Artificial Intelligence \\ BER & Bit Error Rate \\ BPF & Bandpass Filter \\ CFO & Carrier Frequency Offset \\ CIR & Channel Impulse Response \\ CP-OFDM & Cyclic Prefix Orthogonal Frequency Division Multiplexing \\ CSI & Channel State Information \\ CPM & Continuous Phase Modulation \\ DFE & Decision Feedback Equalizer \\ DFT & Discrete Fourier Transform \\ \hline \hline \end{tabular}
\end{table} 
Table 1: List of Abbreviations. Figure 1: Outline of UWA physical layer technologies, channel problems, and challenges.
## 2 Materials and Methods
### Multiphoton Nonlinear Optical Microscope with a Microcubator  
The imaging system is a femtosecond laser-based multiphoton nonlinear optical microscope with submicron 3D spatial resolution. The laser wavelength operates at approximately 1230 nm, which falls in the penetration window (1200-1300 nm) of most biological tissues. The penetration depth at 1230 nm is about 425 \(\mathrm{\SIUnitSymbolMicro m}\). Our home-build laser has a 25 nm full-width at half maximum in the power spectrum, 100 fs pulse-width, and a 110 MHz pulse repetition rate. The average power after the objective was 60 mW, corresponding to a 5454 W instantaneous peak power for each laser pulse. Compared with the commonly used Ti: sapphire laser (700-1000 nm), this wavelength does not two-photon excite the Soret band of many endogenous fluorophores in cells and tissues and thus has minor on-focus damage. With these advantages of in vivo imaging in deep tissues, it has been widely applied in developmental biology studies [19] and human clinical use [20,21], Because most autofluorescence is suppressed, optical contrast agents that can efficiently excite approximately 615 nm would have high contrast and benefit deep tissue imaging. The laser beam was XY-scanned by a scanning unit (FV300, Olympus, Tokyo,Japan) cascaded with an inverted microscope (IX71, Olympus, Tokyo, Japan). The laser beam then transmitted a multiphoton dichroic beam splitter (edged at 665 nm) and focused by a water immersion objective (NA = 1.2, 60X, Olympus). The generated two-photon fluorescence (TPF), second harmonic generation (SHG), and third harmonic generation (THG) were epi-collected by the same objective. The TPF signals (>665 nm) transmit a dichroic beamsplitter and are detected by a photomultiplier tube (PMT) in the scanning unit. The SHG and THG signals were reflected and then separated by another dichroic beam splitter edged at 490 nm. They were detected separately by two other PMTs. All three channels of signals were reconstructed to 512 \(\times\) 512 images with software in a computer with a 2-Hz frame rate.  
To image live cells, we used a micro incubator on the microscope to create an environment with a temperature of 37 \({}^{\circ}\)C and 5% CO\({}_{2}\)/95% air. The temperature of the thermostat (LAUDA Ecoline Staredition RE 204) was set at 50 \({}^{\circ}\)C to achieve 37 \({}^{\circ}\)C at the distal ends of the objective. The vapor reached the micro incubator through the duct and maintained the micro incubator at approximately 37 \({}^{\circ}\)C. The gas controller (OkO Lab, Pozzuoli, Italy) supplied 5% CO\({}_{2}\) continually and kept the outlet at 1 atm absolute pressure. The water immersion objective with 1.2 NA was heated by a dual temperature controller (TC-144, WARNER Instrument, Hamden, CT, USA), so that the contacting objective could be maintained at approximately 37 \({}^{\circ}\)C. The average power density after the objective is approximately 6.5 \(\times\) 10\({}^{6}\) W/cm\({}^{2}\).
## 3 Simulated Results and Analysis
### Effects of the Dominant Mode (\(TE_{101}\)) of the Rectangular Cavity Dimensions  
Normally, the effects of the dominant mode (\(TE_{101}\)) of the rectangular cavity dimensions vary according to the rectangular cavity dimensions '\(c_{x}\)' = '\(c_{y}\)' whereas other parameters are fixed. The following parameter values are fixed: the positions of the rectangular cavity '\(d_{y}\)', the square patch length '\(l_{p}\)', the rectangular slot length '\(l_{s}\)', the rectangular slot width '\(w_{
# Hybrid Task Allocation of an AGV System for Task Groups of an Assembly Line
## 3 Problem Definition  
In a BCAL, the assembly operations involve a variety of materials with significant differences in size, shape and weight; the task allocation problem is a typical hybrid task allocation problem. Therefore, we take the task allocation problem in the BCAL as the research object.  
A BCAL with an AGV system is simplified, the schematic layout is shown in Figure 1. The BCAL simplified consists of processing line 1 and processing line 2, and it contains 16 stations. Each station is equipped with a storage area for accessories. A bus under manufacturing enters the BCAL from station 1, passes through each station of processing line 1 in sequence, and the corresponding operation is completed at the same time, and then enters the buffer area, after that, it enters processing line 2 and passes through each station in sequence; after all the operations in processing line 2 are completed, it leaves the BCAL from station 16. Each operation needs to consume some materials, which are stored in a parts warehouse before being sent to stations by AGVs. Some materials, such as bus chassis frames and front axle assemblies, need to be transported by a multi-AGV group because they are too large or heavy for an AGV. Some materials, such as tires, can be transported by an AGV individually. It should be noted that an AGV can transport several sets of accessories concurrently for a station, for small-sized and lightweight accessories. When an AGV handles a task, it first departs from its current location, then arrives at the parts warehouse and waits for loading until other AGVs handling the same task arrive at the parts warehouse; then it reaches the target station and unloads the materials after the start time and finally stays at the target station until it handles the next task. We should notice that when the AGVs assigned to handle a task are not from the same multi-AGV group, there will be a disassembly time \(\Delta t_{\text{b}}\) to disassemble old multi-AGV groups and an adjustment time \(\Delta t_{\text{c}}\) to combine these AGVs into a new multi-AGV group.  
As shown in Figure 1, a task group, consisting of a two-AGV task T1 and a four-AGV task T2, serves the next operation at station 1. There is a cooperative relationship between the two multi-AGV tasks. When anyone of them is late, the operation cannot begin and the station will be idle.
## 4 Experimental Stations
### Experimental Station Bernina
#### 4.2.11 trRIXS and Energy Analyzer  
In 5d transition metal oxides such as iridates, the strong spin-orbit coupling--in addition to the complex interactions of spin, charge, orbital and lattice--mixes spin and electronic degrees of freedom. New classes of materials are predicted such as quantum spin liquids, topological insulators and new superconductors. High resolution hard X-ray spectrometers (resolving power \(\simeq 2\times 10^{5}\)) to perform momentum resolved RIXS (qRIXS) experiments exist at synchrotrons [177; 178] and a first fs time-resolved qRIXS experiment has recently been performed to directly determine the dynamics of magnetic correlations for the Mott insulator Sr\({}_{2}\)IrO\({}_{4}\)[179]. At Bernina to study mixed electro-magnetic modes and spin correlation dynamics in Ir-perovskites, a dedicated compact qRIXS spectrometer is being designed that can be mounted both on the GPS goniometer and on the dual-arm of the six-circle diffractometer. It is operated in horizontal scattering geometry with the incident photon polarization in the scattering plane. Using the Si(444) reflection of the DCM Si(111) and a spherically-bent, diced Si(844) crystal located one meter away from the sample, the overall energy resolution at the Ir L\({}_{3}\)-edge (11.216 keV) is \(<\)100 meV. The position-sensitive detector is a 0.5 M JUNGFRAU pixel detector or a position-sensitive silicon microstrip detector mounted in Rowland geometry with the diced spherical analyzer. Momentum-resolved trRIXS will greatly benefit from the enhanced spectral flux by self-seeding operation [168; 180] of Aramis in the future.
## 3 Characterization of the Compounds Presented in Balsamic Vinegas
### Phenolic Compounds  
Phenolic compounds belong to the group of substances called antioxidants [93], as they help fight oxidative stress, which can be the cause of liver, neurodegenerative, and cardiovascular diseases [94; 95]. Their presence in vinears is associated with original raw material, aging in wooden barrels (e.g., siringol, eugenol), or with the biological decarboxylation of acids (e.g., ethylphenol, ethylguaiacol) [10]. Although some phenols may have a beneficial effect on the overall aroma of vinegar (e.g., vanillin, eugenol), yeast-formed phenols have a negative impact on organoleptic properties, and their aroma is characterized as a spicy, animal, etc. [96; 97].  
Various volatile phenolic compounds have been identified in balsamic vinears [10; 35; 39; 41; 96]. The main phenols in vinears are phenolic acids, which, because of their lower volatility, cannot be identified by GC without derivatization procedures. Therefore, HPLC predominates in their analysis, but phenols can be determined by GC after derivatization with bis(trimethylsilyl)trifluoroacetamide [98].  
HPLC coupled with DAD or MS detection is the most commonly used method for the analysis of phenolic compounds in samples with a complicated matrix, such as vinegars [11; 62; 63; 64; 65; 96]. The main phenolic compound is gallic acid (Figure 6), whose content increases during maturation in chestnut barrels [64]. On the contrary, in other types of vinegar, gallic acid belongs to substances with a minor content. At the same time, balsamic vinears have the highest antioxidant activity compared to other vinears [62; 63]. Phenolic acids generally have higher content in balsamic vinears than other groups of phenols. In addition to gallic acid, other major acids are protocatechuric acid, caffe acid, and \(p\)-comaric acid. Of the other substances, protocatechuric aldehyde, ethyl gallate, and tyrosol should be referred to [11; 65; 96].  
Figure 6: Comparison of the phenolic profile of balsamic vinegar samples obtained by HPLC analysis. Blue box—Greek balsamic vinegar; Red box—BVM; Green box—”premium” BVM; Purple box—TBVM. The first compound is gallic acid. Figure adapted from [96].
## 5 Guidance of Traffic Parameters for Signal Control Optimization
### Decision Support for Offset Optimization  
Offset constitutes the core parameter for arterial coordination control, directly affecting green wave bandwidth and coordination effectiveness. Link average travel times and average speeds extracted from trajectory data provide precise data foundation for offset calculation and optimization.  
Traditional offset calculation typically assumes constant vehicle speeds, while actual traffic flow speeds exhibit significant spatiotemporal variations. By analyzing travel time distribution characteristics across different time periods and links, a more refined offset design can be achieved:  
1. Basic offset determination: Calculate typical travel times between adjacent intersections based on link average travel times. For instance, if a link's average travel time is 45 s, the basic offset should be set as an integer multiple of 45 s to ensure vehicles can pass through downstream intersections during green phases.
2. Dynamic adjustment strategy: For links with high speed fluctuations (such as link '4,6' and links '21,22' and '16,22' in the experimental results), offsets need fine-tuning based on speed distribution standard deviations. When standard deviations are large, safety margins for offsets should be appropriately increased to prevent vehicles from missing green phases due to speed fluctuations.
3. Tidal phenomenon response: Pronounced directional imbalances exist during morning peak periods. Through analyzing bidirectional flow ratios and speed differences, offsets can be optimized accordingly. Experimental data indicates that directions 8-1, 16-9, and 22-17 (reverse green waves) carry substantial flows during morning peaks, warranting increased green wave bandwidth in these directions with corresponding offset adjustments to match actual demands.
4. Multi-path coordination: Based on OD matrix analysis, identify primary traffic flow paths and ensure offset settings along critical paths can form continuous green wave effects. This multi-path offset optimization approach can enhance overall network operational efficiency.
# Gating Hysteresis as an Indicator for Silicon Nanowire FET Biosensors
## 1 Introduction
Here we present a thrombin detection platform using large area Schottky barrier silicon NW FET devices, which consist of multiple nanowires connected in parallel, and integrated into a microfluidic channel for sensing purposes. The Schottky barrier silicon NW transducers do not require doping, strongly simplifying the technological complexity compared to other ion-sensitive FET approaches. We have recently proven that the Schottky junctions do not impair the sensitivity of the devices, since near Nernstian sensitivity can be reached [32]. As demonstrated recently [8; 32; 33; 34; 35], such multi-wire devices, assembled using a thin-film-transistor (TFT) format, reveal remarkably high output currents (up to \(\sim\)mA) preserving the high on-to-off current ratio (in average up to \(\sim\)10\({}^{6}\)), which greatly outperform the single wire FET, mostly employed for biosensor measurements [33]. Thus, devices connected by NW arrays are able to deliver a broader dynamic range for the measurements and lower device-to-device variation in current and sensitivity due to the averaging of the different signals coming from the individual wires [36; 37]. These aspects are critically important for ISFET devices in general and are considered to be typical drawbacks of sensors encompassing individual nanowire channels, in particular. Human \(\upalpha\)-thrombin is further detected in a wide dynamic range and down to 200 pM, at real time analyzing the FET transfer curves upon the gradual increase of the molecules' concentration. Here we explore the continuous gate sweeping mode (change of the voltage from negative to positive values and back) to monitor the entire transfer characteristic shift in a time domain (Figure 1a). Furthermore, we follow the evolution and shrinkage of the hysteresis in the transfer curves (Figure 1b) of the NW FET [38], which is observed frequently for the nanoscaled devices in the gate sweeping regime. For the first time we implement the hysteresis width as a reliable parameter to control and calibrate the concentration of biomolecules in solution. Interestingly, these observations partially resemble the appearance of a voltage hysteresis in output curves when sweeping source-to-drain voltage \(V_{SD}\) upon functionalization with antibodies in silicon nanowire devices that were modelled by a memristor equation, and related to the capacitive effects [39; 40]. Finally, we compare the sensing results obtained via quantitative analysis of hysteresis, with the results obtained from the voltage shift \(dV_{T}\) in the subthreshold region [41], and demonstrate the qualitative agreement for both methods.
###### Abstract  
For underwater vehicles navigating in Arctic Sea ice-covered waters, fatigue damage is a crucial issue. Many scholars have conducted low-temperature fatigue analysis on low-temperature materials and substrate platforms for ships, and the results show that low temperature is beneficial for improving the mechanical properties of materials. However, they have mainly focused on low-temperature performance experiments and simulation analysis of standard components of materials, and there are very few fatigue life experimental studies on underwater vehicle mechanical structures. This paper conducts experimental investigations on a scaled model of an underwater vehicle rudder mechanism in a polar environment laboratory. Using a comparative analysis method involving simulations and experiments, the low-temperature fatigue test data of the scaled underwater vehicle rudder mechanism are analyzed, and the quantified analysis between fatigue and different low-temperature loading cycles, as well as the influence of icing on the fatigue life, is explored. It is indicated that the Arctic environment can decrease the fatigue life of the underwater vehicle rudder mechanism by deteriorating its material properties. The paper builds the foundation for the fatigue life of an underwater vehicle rudder mechanism in Arctic low-temperature environments.  
arctic; low temperature; rudder; fatigue Article
## 4 Results
### Results to Minimize Energy Consumption  
The results shown in Table 8 were obtained from the measurements taken to know the energy consumption for each of the 19 mm and 25 mm specimens. Together with the mean, the table shows the signal-to-noise ratio (S/N) using a smaller-the-better quality response, as it was desired to minimize energy consumption. As with the surface roughness, a high S/N ratio represents an experiment where the combination of factors and levels provides a more robust response, meaning that the energy consumption changes less from one replicate to the next. A low mean represents lower energy consumption.  
Figure 8: Contour plot of the S/N ratio for the surface roughness as a function of pulse on-time (Ton) and voltage (V) within the limits studied. As the values of the S/N ratio are negative, values closer to zero are better.  
Figure 9: Contour plot of the mean for the surface roughness as a function of pulse on-time (Ton) and voltage (V) within the limits studied. Smaller values are better.  
Table 12 summarizes the levels that minimize the surface roughness and the energy consumption, together with the contribution percentages that the factors have for each of the responses. Ideally, suppose one factor has a strong contribution to one response and a weak one to the other. In that case, it is possible to say that it is more convenient to select as a better value than the one that improves the result on the response where the factor has a strong influence. However, if such a decision cannot be simply made because the percentage contribution to both responses is similar, other methods or performance characteristics must be considered.  
Fortunately, the simple approach described above worked here. The pulse on-time (Ion) had a contribution of around 42% for the energy consumption and around 68% for the surface roughness. Hence, it was possible to select the level for Ton based on the result that minimized the surface roughness, which was level 1.  
For the voltage (V), its contribution to the energy consumption was around 50% whereas for the surface roughness, it was around 23%. Therefore, the best level for the voltage could be selected based on the results of the energy consumption, that is, level 3.  
The wire tension (WT) level could be selected based on the energy consumption alone, since it was only relevant for that response. In consequence, the best level for the wire tension was level 3.  
Wire speed was a weak contributor to both responses, so any of the levels chosen for this factor could work. Higher wire speeds could lead to increased machining efficiency and a higher material removal rate, so a wire speed of 7 m/min, corresponding to its level 3, was chosen.  
Using the above arguments, the levels that optimized both responses were a pulse on-time of 10, a pulse off-time of 11, a servo voltage of 44 volts, a wire tension of 50 g-force, a wire speed of 7 m/min, and a voltage of 9 volts.