esa-sceva/satcom-chunk-collection huggingface dataset:
# Performance Evaluation of a Novel Propulsion System for the Spherical Underwater Robot (SURIII)
## 5 Experiments and Results  
For evaluating the performance of the novel propulsion system, some experiments are conducted in this section. An inflatable swimming pool is prepared with the water at the depth of 25 cm. A load cell with 6-DoF is employed to measure the propulsive force of the multi-vectored water-jet thrusters. Two power supplies are employed as the electric source and each one will give a 7.2 voltage power to two vectored water-jet thrusters. The experimental setup is shown in Figure 18. All vectored water-jet thrusters are connected with the load cell by using the aluminum alloy profile and it can be considered as rigid connection. And all the support parts of the experimental setup are also rigid bodies.  
Although the SURIII has 4 DoFs, our experiments only include three different cases as the low-speed mode for the forward motion, high-speed mode for the forward motion and upward motion due to the limitation of experimental conditions. Each case will be carried out for 10 times.  
Figure 17: Forward motion in surge. (**a**) Pressure contour; (**b**) Velocity vector; (**c**) Velocity streamline.  
Figure 19 displays the experimental results. The average propulsive force for each time is shown in each case. The average propulsive forces of 10 experiments for each case are 3.57 N, 5.36 N and 7.27 N, respectively. In our previous research, the SURII also has two modes for forward motion. Although an experiment which measured propulsive force of single thruster was conducted, the propulsive force of the high-speed motion and up motion can be calculated by vector synthesis. The maximum propulsive force of forward motion is \(2\sqrt{3}\) N. The maximum propulsive force of up motion is 6 N [21]. It indicates that the propulsive force of the novel propulsion system in forward and up motion is better than before. In this experiment, the vectored water-jet thrusters performed in a stable manner. In either case, the changed amplitude of the propulsive force compared with the average value is within 6%.  
The Equation (11) shows the relationship between mass, resistance and propulsive force. Although the SURIII is 0.6 kg heavier than SURII in air, the resistance variety is not greater than the previous research [21]. The variety of mass underwater is less than that in air and the propulsive force is improved significantly, so the speed of the SURIII will be enhanced. When the robot moves at a constant speed, the acceleration is equal to 0, then from Equation (11) the resistance can be obtained and is equals to the propulsive force. The movement process of the SURIII can be inferred, the initial stage is an acceleration process, the propulsive force will be greater than the resistance, then the speed of the robot reaches a constant, the propulsive force will be the same as the resistance, finally the robot reaches the target and the speed is slow down, the propulsive force will be less than the resistance.  
Figure 18: The experimental setup. (**a**) Top view; (**b**) Side view.
# Noninvasive Suspicious Liquid Detection Using Wireless Signals
## 1 Introduction
As the information of the physical layer, the fine-grained WCI contains a lot of channel information which is invisible to the Medium Access Control (MAC) layer. The WCI can measure the frequency response of multiple subcarriers at the same time from a single packet, rather than the overall amplitude response superimposed by all subcarriers. Information about the WCI and frequency-selective channels is described [11]. In the field of wireless sensing, WCI has gradually become a popular area of research [12], such as indoor positioning [13; 14; 15], respiration detection [16; 17; 18], and behavior recognition [19; 20]. [PERSON] et al. proposed using the WCI to detect the presence of people in the environment [21]. Although wireless signals have good applications in indoor positioning and fall detection, there are still relatively few studies on detecting the types and concentrations of liquids by using them. Liquid interferes with the path of radio signals. Different liquids have different degrees of interference to the radio signal propagation path due to their differences in dielectric constants, which leads to different changes in the WCI. These changes can be effectively observed at the signal receiver, so as to realize the detection and identification of various liquids. Table 1 shows the relative dielectric constants of common objects. Following this introduction, the paper is organized into four sections. Section 2 describes the preparatory work. Section 3 details the band selection and method design. Results are analyzed in Section 4 and conclusions are drawn in Section 5. \begin{table}
\begin{tabular}{c c} \hline \hline
**Object** & **Dielectric Constant** \\ \hline Water & 80 \\ Alcohol & 24 \\ Oil & 2 \\ Glycerol & 37 \\ Methanol & 32 \\ Sulfuric Acid & 84 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The relative dielectric constants of common objects.
## 2 Operation and Specifications of the Optoelectronic FDS System
### Other THZ Spectrometers for Comparison Measurements  
The performance of the T-Sweeper was tested by comparing it with two commercially available THz spectrometer instruments: a TDS and FDS, which had been previously calibrated and validated.  
The TDS was a TeraFlash pro from TOPTICA Photonics, employing 1550 nm fibre laser technology and InGaAs photoconductive switches as the emitter and receiver. The THz beam path was the standard configuration of four F/2 parabolic mirrors; an example of this system's performance can be observed in [23]. The THz beam path was contained in an enclosure purged with dry air to eliminate absorption by the atmospheric water vapour. The frequency resolution was set to 5 GHz; and 1000 time-domain averages were used for all measurements. With these settings, the maximum dynamic range was 93 dB, and the cut-off frequency was 5.6 THz.  
The FDS was TeraScan from TOPTICA Photonics similarly employing 1550 nm fibre laser technology and InGaAs photoconductive emitter and receiver. The performance comparison with the optoelectronic FMCW system was further aided by using the same emitter and receiver devices and the same THz beam path in both instruments. The frequency range of the TeraScan is comprised of two bands: 0.1-1.33 THz and 1.33-2.18 THz. The frequency step size was set to 50 MHz, and the integration time was 3 ms. For the measurements with the FDS systems, the terahertz beam path was contained in an enclosure purged with dry air to eliminate absorption by atmospheric water vapour.  
Both TeraFlash pro and TeraScan have been previously calibrated and tested using the same procedures as described below for the T-Sweeper.
## 3 Important Factors in Efficacy of Amphiphiles
### Role of Time  
Role of incubation period of amphiphiles with biomass is an important factor in determining the efficiency of enzymatic hydrolysis. As a result of the recent investigation on this subject, [PERSON] _et al._[73] showed that without PEG 4000 the irreversible adsorption of CBH I to corn stover was about 85% of added enzyme. However, as the time interval of the incubation of corn stover with PEG 4000 was increased from 0.5 h to 1 h and 2 h, the adsorption of CBH I was reduced to 73.75%, 69.37% and 67.22%, respectively. According to this author, as the incubation period increased up to 2 h, the PEG was twisted and whorled further into the lignin which helped to the CBHI desorption by enhancing the hydration shell around the biomass (specially lignin), which generated a higher steric repulsion impact on enzymes.  
Cellulolytic enzymes would otherwise be irreversibly adsorbed by non-productive sites and be deactivated. As a result, the glucose yield was increased by 8.1%, when the incubation interval was raised from 0.5 h to 1 h. However, a significant increase was not observed when further extension in incubation up to 2 h was conducted [73]. According to a systematic study conducted by [PERSON] _et al._[36] to understand the role of incubation time of PEG or Tween 20 with high lignin containing corn stover prior to hydrolysis, time (1-5 h) was not found to be a significant factor. Perhaps further research in this topic can help elucidate the role of this factor.  
It was also proposed that the impacts of enzyme stabilizers are improved to a higher extent as the hydrolysis reaction progressed up to 72 h. According to [PERSON] and [PERSON], [26] at a cellulase and \(\beta\)-glucosidase level of 16.1 and 6.2 mg/g glucan, extending the hydrolysis from 24 h to 72 h for Avicel increased the sugar yield from 14%-19% to \(\sim\)30% when 0.3-0.6 g/g glucan of enzyme stabilizer (e.g., BSA, Tween 20, PEG 6000) was used. It is possible that amphiphiles protect cellulolytic enzyme from the higher inactivation by the increased thermal and shear forces associated with extended hydrolysis time.
## 5 Pre-Identification Method for Continuous Low Thrust Parameters
### Pre-Identification Method of Continuous Normal Thrust Parameters for Changing Inclination  
If \(a_{\mathrm{T}}=0\), i.e., the semi-major axis is constant, then the inclination of the orbit will vary linearly under the action of continuous normal thrusts.  
\[i=i_{0}+\frac{2}{\pi na}a_{\mathrm{N}}t \tag{21}\]  
If \(a_{\mathrm{T}}\
eq 0\), the semi-major axis a varies under the action of tangential thrust, from Equation (20)  
\[a(t)=\frac{\mu}{\Big{(}\sqrt{\frac{\mu}{a_{0}}}-a_{\mathrm{T}}t\Big{)}^{2}} \tag{22}\]  
Substituting Equation (22) into Equation (21) gives  
\[\mathrm{d}i=\frac{2a_{\mathrm{N}}}{\pi n}\left[\frac{\Big{(}\sqrt{\frac{\mu} {a_{0}}}-a_{\mathrm{T}}t\Big{)}^{2}}{\mu}\right]\mathrm{d}t \tag{23}\]  
Integrating both sides gives  
\[i=-\frac{2a_{\mathrm{N}}}{3\pi n\mu a_{\mathrm{T}}}\bigg{(}\sqrt{\frac{\mu}{ a_{0}}}-a_{\mathrm{T}}t\bigg{)}^{3}+c_{i} \tag{24}\]\(c_{i}\) is the constant of integration, when \(t=0\), \(i=i_{0}=-\frac{2a_{\rm N}}{3\pi n\mu a_{\rm T}}\cdot\left(\sqrt{\frac{\mu}{a_{0}}} \right)^{3}+c_{i}\), then  
\[c_{i}=i_{0}+\frac{2a_{\rm N}}{3\pi n\mu a_{\rm T}}\cdot\left(\sqrt{\frac{\mu}{a_ {0}}}\right)^{3} \tag{25}\]  
\[i=i_{0}-\frac{2a_{\rm N}}{3\pi n\mu a_{\rm T}}\left(\sqrt{\frac{\mu}{a_{0}}}-a _{\rm T}t\right)^{3}+\frac{2a_{\rm N}}{3\pi a_{\rm T}} \tag{26}\]  
According to Equation (26), the normal acceleration can be solved from the amount of change in the inclination of the track, the magnitude of the tangential acceleration, and the time interval between the two arc segments.
## 3 EM Analytical Model
### EM Models for Non-Segmented PMS Machines
#### 3.1.2 Cogging Torque  
An analytical cogging torque model is presented in [10]. In this model, the calculation of cogging torque is based on the estimation of the magnetic pressure applied on each slot opening frontiers. The magnetic flux density created by the rotor \(B_{/R}\) is first evaluated in each stator openings and the contributions of each slot frontier are added as shown in (3), for a position of the rotor \(\theta_{r}\).  
\[T_{c,slotted}(\theta_{r})=\frac{L_{z}}{2\mu_{0}}\times\left[\sum_{1}^{Q_{0}} \left\{\int_{\frac{\theta_{r}}{2}}^{\epsilon_{s}}B_{/R}^{2}(\theta)\times(R_{ s}+r_{fl}(\theta))d\theta-\int_{0}^{\frac{\theta_{r}}{2}}B_{/R}^{2}(\theta) \times(R_{s}+r_{fl}(\theta))d\theta\right\}\right] \tag{3}\]  
In the Equation (3), \(\epsilon_{s}\) is the slot-opening width and \(r_{fl}\) is an additional length corresponding to the flux line radius applied on the slot side at the position \(\theta\) as shown in Figure 4. \(R_{s}\) is the internal stator radius, \(L_{z}\) is the iron axial length of the machine, \(\mu_{0}\) the permeability of free space and \(Q_{s}\) is the number of slots.
# Achievable Rate Maximization for Multi-Relay AF Cooperative SWIPT Systems with a Nonlinear EH Model
## 5 Conclusions  
In this paper, we have proposed the optimal TS and PS schemes for the maximization of the achievable rate for the SWIPT multi-relay cooperative AF communication system with a nonlinear EH model. The impact of the resource allocation mismatch due to using the traditional linear EH model in modeling realistic nonlinear EH circuit on the performance, has been investigated for both of the proposed TS and PS schemes. The effect of the relays' position and the channel parameters on the system performance has also been investigated. Simulation results have demonstrated that the use of the linear EH model in modeling the practical EH circuit for the resource allocation brings significant performance degradation for the TS scheme, whereas inconspicuous performance change was observed for the PS scheme. It has also been demonstrated that the TS scheme is more susceptible to the resource allocation mismatch than the PS scheme for given channel parameters, and that the PS scheme is more susceptible to the variation of the relays' location and the channel parameters than the TS scheme.  
**Author Contributions**: Conceptualization and methodology, Y.F.; software and validation, Y.F.; formal analysis and data curation, Y.F.; writing--original draft preparation, Y.F. and Y.C.; supervision, Y.F.; funding acquisition, Y.F. and Y.C. All authors have read and agreed to the published version of the manuscript.  
**Funding**: This research was funded by the National Natural Science Foundation of China, grant number 62171187 and 61871191, the Natural Science Foundation of Guangdong Province, grant number 2214050002022, and the Science and Technology Program of Guangzhou, grant number 201904010373.  
**Institutional Review Board Statement**: Not applicable.  
**Informed Consent Statement**: Not applicable.  
**Data Availability Statement**: The data presented in this study are available on request from the corresponding author.  
**Conflicts of Interest**: The authors declare no conflict of interest.
# BVLOS Unmanned Aircraft Operations in Forest Environments
## 3 BVLOS Operations
### Scenario 1: Soft BVLOS  
Scenario 1 represents a situation that most foresters will face regularly when utilising unmanned aircraft for monitoring and management purposes. In this example, a forester is wanting to fly over a 20 ha rectangular stand of mature _Pinus radiata_ in the 40 m tall height range. The only take-off location is a small skid site on the side of a forest road at one side of the stand that has been kept open, and the skid site is surrounded on all sides by 40 m tall trees. The stand is surrounded, on all sides, by the same age class, and there are also no nearby high points from which to fly from, as the terrain is flat; therefore, the skid is the best take-off point. There is very limited VLOS to the craft and the surrounding airspace from any of the open spaces surrounding the stand, making VLOS operations impossible from this location. EVLOS is not an option here due to the height of the trees, and the height of the neighbouring trees, restricting visibility over the entire stand. It might be possible to bring in a MEWP to raise the height that the pilot is flying from above the height of the trees. However, this would be expensive--due to the height of the trees--and may not be possible given the lack of developed roads. It is also possible to climb trees, but that would require certified climbers who are also experienced unmanned aircraft pilots: labour that will not be cost-efficient due to the highly specialised nature of the work. The use of either a MEWP or climbers would add costs to the point where it might even be cheaper to use a small manned aircraft for the same operation. Figure 3 illustrates the operating area that is described in scenario 1.
## 6 Conclusions  
In this paper, an optimization model based on MILP was introduced with the aim of finding the optimum speed profile for an AEV while considering an important limitation of RB that makes it challenging for the electric motor to extract energy at low speeds. This limitation was further elucidated by analyzing the results of an experimental test on a test motor. The importance of considering this physical RB limitation in finding the optimal speed trajectory was demonstrated by examining two scenarios, of which in only one scenario this constraint was considered in the decision-making process. For each scenario, the results of the MILP-generated profiles were simulated using a MATLAB/SIMULINK simulation model which enabled accurate energy consumption calculations. It was concluded that in the scenario utilizing the proposed approach, 27% more energy could be harvested through RB.  
This study highlights the decisive effect of considering the RB low-speed limitation in the decision-making process when finding optimum speed profiles for AEVs and concludes that if this limitation is not taken into account during the optimization process, noticeably less energy will be recaptured during RB.  
Conceptualization, M.M., P.F. and R.S.; methodology, M.M., P.F. and F.H.; software, M.M. and P.F.; validation, M.M., P.F., R.S. and F.H.; formal analysis, writing--original draft preparation, M.M. and P.F.; writing--review and editing, M.M., P.F., R.S. and F.H.; supervision, P.F. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflict of interest.
## 5 Discussion
### Limitations in Satisfying Security Requirements for Offline Payment Function
#### 5.2.1 Solutions to Satisfy Security Requirement of Unforgeability  
* [PERSON] et al.'s [93] method: In the case of CBDC, using the distributed ledger scheme, forgery attacks can be prevented through the time-based transaction confirmation verification mechanism proposed by [PERSON] et al. [93]. In the blockchain methods available, n--confirmation blocks had to be created to confirm the transaction. Based on this method, in an offline situation using the time-based transaction confirmation verification mechanism, the attacker is forced to create n--confirmation blocks within the time limit \(n\delta\). Thus, the probability of forgery is reduced. The probabilistic relationship between delta and the probability of forgery is described in detail in Section 4.2.
* Method of modifying the increasing conditions of a counter of a device and using sync: In this method, after modification of the increasing conditions of a counter of a device, it is possible to confirm that a forgery attack has occurred through sync. Table 4 shows the description of the variables used.  
To use this method, it is necessary to modify the conditions for T.i to increase. In the current method, the increase in T.i occurred secondary to withdrawal (a process of transferring balances from an online account to an offline wallet) or deposit (a process of transferring money from an offline wallet to an online account). During the process for withdrawal and deposit, when all T.bal changes except the offline payment, the condition  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Variable** & **Definition** & **Function** \\ \hline T.i & A counter in a device & A variable that increases by 1 when a withdraw protocol or deposit protocol \\  & & occurs, indicating how many times both protocols have progressed. \\ \hline S.i & A counter in a server & A variable that increases by 1 when a withdraw protocol or deposit protocol \\  & & occurs along with T.i. \\ \hline T.bal & Account balance of a device & The amount of money the offline payment device holds to make a transaction. \\ \hline \hline \end{tabular}
\end{table}
Table 4: Variables are used in modifying the increasing conditions of the counter of a device and using sync.  
must be modified to increase T.i. Applying this modification will increase T.i when money is forged in offline wallets, in addition to the withdrawal and deposit processes. Next, when the sync process occurs, if the offline payment device intentionally rejects the sync operation, or if the values of T.i and S.i are different, the transaction of the corresponding device must be blocked entirely. Figure 5 is a schematic diagram of the above method.
## 2 Study Areas and Data Sources
### Data Sources  
By the end of 2022, 2681 landslides had been reported in the Liangshan Prefecture. Statistical analysis indicated that earth landslides were the most prevalent, with 2619 occurrences, accounting for 97.7% of the total. In contrast, rocky landslides are relatively rare, with only 62 occurrences, representing 2.3% of the cases. The landslide data and sources of the evaluation factors used in this study are presented in Table 1.  
Figure 1: Geographic overview and landslide distribution in the Liangshan Yi Autonomous Prefecture.
## 9 Experimentation
### Libraries and Frameworks  
The Contiki operating system (OS) and Contiki programming language, which were created especially for CPS devices with limited resources, were used in the experimental setup. The features and protocols required to simulate CPS devices inside the Cooja environment were given by Contiki. The Cooja simulator used a variety of frameworks and libraries, including:  
1. RPL Classic: The ulP stack has capabilities including packet processing, routing, and communication protocols and supports IPv6. It ensured that the CPS network was routed effectively and consistently, which assisted in the evaluation and realistic behavior of the trust mechanisms.
2. Managing Trust: A trust-managing library (TinyDTLS) was employed in the GBG-RPL technique to facilitate the detection of blackhole and greyhole attacks. With the help of these libraries, trust values could be managed and calculated while accounting for a number of variables, such as message overhead, energy consumption, packet loss, and end-to-end delay.
3. Blockchain Library (web3.js): The web3.js package was used to include blockchain technology.