esa-sceva/satcom-chunk-collection huggingface dataset:
# Effects of Isometric and Isotonic Training on Health-Related Fitness Components in Young Adults
###### Abstract  
Isometric and isotonic exercises are important modes of resistance training for enhancement of athletic performance. However, less is known about their effects on fitness and health in recreationally physically active individuals. This study evaluates the effect of isometric and isotonic training protocols on health-related fitness components in young university students. A group of one hundred males (18-24 years) underwent a 12-week isotonic and isometric training program (two days per week, 45 min per session). They were randomized into two groups, group A (\(n=50\)) and group B (\(n=50\)). While group A underwent the isotonic resistance training, the group B completed isometric resistance training. Prior to and after training programs, body mass index (BMI) was measured and the bench press 1 RM test, sit-ups test, sit and reach test, and 12 min run/walk test were performed. Results showed significant improvements in BMI, bench press 1 RM test, sit-ups test, sit and reach test, and 12 min run/walk test after both isotonic and isometric training protocols. The isotonic training group increased in BMI by 2.70%, bench press 1 RM by 34.45%, number of sit-ups by 24.13%, sit and reach distance by 29.12%, and 12 min run/walk distance by 19.82%. Isometric training group increased in BMI by 1.96%, between press 1 RM by 14.23%, number of sit-ups by 7.80%, sit and reach distance by 6.92%, and 12 min run/walk distance by 6.99%. A comparison of these training protocols revealed that the isotonic group improved significantly more than the isometric group in the bench press 1 RM (20.22%), number of sit-ups (16.33%), and sit and reach distance (22.2%) but not in the 12 min run/walk distance (12.83%) and BMI (0.74%). These findings indicate that both isotonic and isometric resistance training protocols improve health-related fitness components in young adults; however isotonic training is more efficient than isometric training in increasing their muscle strength, muscular endurance, and flexibility.  
c 2022 2022  
2  
Acdiovascular endurance; flexibility; muscular endurance; muscle strength; resistance training
# Self-Organized Fast Routing Protocol for Radial Underwater Networks
###### Abstract  
An underwater wireless sensor networks (UWSNs) is an emerging technology for environmental monitoring and surveillance. One of the side effects of the low propagation speed of acoustic waves is that routing protocols of terrestrial wireless networks are not applicable. To address this problem, routing strategies focused on different aspects have been proposed: location free, location based, opportunistic, cluster based, energy efficient, etc. These mechanisms usually require measuring additional parameters, such as the angle of arrival of the signal or the depth of the node, which makes them less efficient in terms of energy conservation. In this paper, we propose a cross-layer proactive routing initialization mechanism that does not require additional measurements and, at the same time, is energy efficient. The algorithm is designed to recreate a radial topology with a gateway node, such that packets always use the shortest possible path from source to sink, thus minimizing consumed energy. Collisions are avoided as much as possible during the path initialization. The algorithm is suitable for 2D or 3D areas, and automatically adapts to a varying number of nodes, allowing one to expand or decrease the networked volume easily.  
Keywords:underwater; UWSN; location free; routing protocol; self-organized; self-configured; wireless networks; proactive +
Footnote †: journal: Sensors
## 6 Results and Discussions
### The Shell Centre Case  
The heat transfer coefficient value across the concrete-soil interface was adjusted from 3 to 6 (Wm\({}^{-2}\)K\({}^{-1}\)). Figure 13 shows that when \(h=6\) Wm\({}^{-2}\)K\({}^{-1}\), the curves match each other in the three heating mode sections, while \(h=4\) Wm\({}^{-2}\)K\({}^{-1}\) makes the curves matched at the cooling mode section. Therefore, the hypothesis described in Methodology is supported in this case.  
In the Shell Centre project, the difference in values of \(h\) is smaller than that of the Lambeth College case. The most likely reason is the pile diameter. In the Lambeth College case, the pile diameter is 610 mm at the top and 550 mm for most of the depth. In the Shell Centre case, the borehole was enlarged to a diameter of 300 mm. As the temperature raises/drops, the pile body can expanse/contracts by a certain rate, therefore the large diameter pile can expanse/contract more movement than the small diameter ones. Therefore, the heat transfer coefficient difference in the Shell Centre is smaller than that of the Lambeth College one.  
Figure 13: _Cont._  
Figure 13: TRT outlet liquid temperatures when the heat transfer coefficient is adjusted.  
There is another probable reason for the smaller heating/cooling effect of Shell Centre case. Not as in Lambeth College case, there is no load on the pile of Shell Centre project. The load may cause side friction at the surface of the pile and the interface between the pile body and the ground could be tighter. A tighter interface can have a better \(h\) across it. Therefore, the impact from the heat extension and cold contraction could be larger as well. Further experiments could be developed to compare the \(h\) change with or without load on the pile.  
Considering the variation of \(h\) on heat transfer is important to secure the stable performance of energy pile in the long-term. The influence of using an appropriate \(h\) value can get increased along with time because of the impact accumulation. Over a long time, the practical system yield can be different from the design value and the problem may come out regarding the uncertainty of energy supply. If the design supply is overestimated, there would be a waste on both the pile and the heat pump capacities. If the design supply is underestimated, the problem can be more severe as lack of energy supply would make people run the system for more operation hours. This action will not only reduce the system lifetime, but also increase the possibility of causing the thermal pollutions of the underground.
## 3 RF-EH Techniques
### RF Energy Transfer between Mobile Devices  
Wireless communication devices are able to serve as RF sources to transfer power among nearby devices stably. Previously, certain RF energy transmitters/receivers were designed to simultaneously transmit/receive power and information. The power splitting or time switching setting provides a cheap approach for sustainable wireless system operations in the absence of any transmitter modification. It allows a similar antenna or antenna array to be used for both the RF-EH and the information receiver. In short, mobile devices can be used to transfer information-based RF energy for the relay nodes to prevent the unbalanced consumption of energy [34].
# Efficient and HRA Secure Universal Conditional Proxy Re-Encryption for Cloud-Based Data Sharing
### Related Work  
[PERSON] et al. [1] proposed the notion of proxy re-encryption to achieve delegation rights from ciphertexts for [PERSON] to ciphertexts for [PERSON]. PRE has many real-world applications, such as outsourcing computation, distributed file storage systems, and secure email forwarding [34]. Since the concept of PRE was introduced by [PERSON] et al. [1], a rich line of works has studied the construction of PRE schemes [2; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21] with kinds of properties to satisfy different application demands. For instance, to integrate PRE into identity-based encryption (IBE) setting, [PERSON] and [PERSON] [6] defined the notion of identity-based proxy re-encryption (IB-PRE). They also proposed two constructions in the random oracle model where the proxy can transfer ciphertexts from [PERSON]'s identity to [PERSON]'s identity. Later on, a PRE scheme with an anonymous technique designed by [PERSON] et al. [9] has anonymous about the identity information of users and holds multisharing that the proxy can conditionally and securely share multiple times a ciphertext. Recently, [PERSON] et al. [10] proposed a new notion of autonomous path PRE in which the delegator designates a privilege path with his predetermined multiple delegatees from high to low. In the meantime, a collusion-resistant IB-PRE scheme is designed by [PERSON] et al. [11] that satisfies a CCA security based on the random oracle. However, the existing PRE schemes cannot support ciphertext switching between two encryption schemes. To solve this issue, [PERSON] and [PERSON] [2] present the notion of universal proxy re-encryption that allows the proxy to convert ciphertext into one of the possibly different encryption schemes. However, this scheme exist some disadvantages: first, it is a relaxed case that the delegator needs to execute a modified decryption algorithm to decrypt the ciphertext; second, the computing costs of the delegatee increase with the number of delegations.  
Another interesting research is conditional proxy re-encryption (CPRE) which was introduced by [PERSON] et al. [22]. CPRE is a variant of PRE, enabling the delegator to enforce fine-grained delegation of decryption rights. Later, [PERSON] et al. [23] proposed a new CPRE scheme by reformalizing the definitions and security concepts. Subsequently, lots of CPRE schemes [24; 25; 26; 27; 28] have been proposed to improve efficiency and security. For instance, [PERSON] et al. [26] proposed a conditional proxy re-encryption scheme based on hierarchical identity-based encryption that is efficient and achieves CCA security. Lately, an identity-based CPRE scheme with a revocable feature for secure cloud data sharing was presented by [PERSON] et al. [27]. In the meantime, [PERSON] et al. [28] presented an efficient CPRE scheme in which there are no pairing operations. Unfortunately, none of these works addressed the ciphertext switching issue.  
Figure 1: UCPRE in a cloud data sharing system.
# Research on Satellite Network Traffic Prediction Based on Improved GRU Neural Network
## 4 Traffic Prediction Method of the AT-GRU Satellite Network
### Design of Decoding Unit Based on Attention Mechanism  
To simplify the model design, the decoding unit still adopts the GRU unit. In the decoding stage, the time attention mechanism and GRU neural network are combined to select and weight the hidden state \(h_{t}\) of the encoder. In this way, the time relationship of the input sequence can be learned. The decoding stage is shown in Figure 4.  
Assuming the hidden state \(h_{t}\) of the encoder at the moment, the attention weight of the hidden state of the encoder can be expressed as  
\[l_{t}=v_{d}^{T}\tanh(W_{d}[d_{t-1},h_{t}]), \tag{10}\]  
\[\beta_{t}=\frac{\exp(l_{t})}{\sum\limits_{j=1}^{T}\exp(l_{t}^{j})}, \tag{11}\]  
where \(d_{t-1}\) represents the historical hidden state of the previous decoder, \(v\) and \(W\_t\) represent the parameters to be learned by the neural network, and \(l_{t}\) can be obtained by the \(\tanh\) transformation. \(\beta\_t\) represents the importance of the hidden state of the \(t\)-th encoder. The intermediate quantity \(c_{t}\) can be calculated as follows:  
\[c_{t}=\sum\limits_{t=1}^{T}\beta_{t}h_{t}. \tag{12}\]  
After obtaining the intermediate vector, combine it with the satellite network traffic data sequence \((y_{1},y_{2},\dots,y_{T})\), as follows:  
\[\widetilde{y}_{t}=W[y_{T},c_{t}]+\widetilde{b}. \tag{13}\]  
The hidden state of the decoder at t time can be expressed as  
\[d_{t}=f_{d}(d_{t-1},\widetilde{y}_{t}), \tag{14}\]  
Figure 4: Decoding stage.  
where \(f_{d}(\cdot)\) stands for GRU unit, and \(d_{t}\) can be updated to:  
\[r_{t}=\sigma(W_{r}[d_{t-1},\widetilde{y}_{t-1}]+b_{r}), \tag{15}\]  
\[z_{t}=\sigma(W_{z}[d_{t-1},\widetilde{y}_{t-1}]+b_{z}), \tag{16}\]  
\[\widetilde{d}_{t}=\tanh\bigl{(}W_{\widetilde{d}}[d_{t-1}\cdot r_{t}, \widetilde{y}_{t-1}]+b_{\widetilde{d}}\bigr{)}, \tag{17}\]  
\[d_{t}=(1-z_{t})\cdot d_{t-1}+z_{t}\cdot\widetilde{d}_{t}, \tag{18}\]  
where \(r_{t}\) is the reset gate, and how many previous states can be controlled by the reset gate that need to be memorized and stored; \(z_{t}\) is the update gate, which is used to control how cells store information; \(W_{r}\), \(W_{z}\), \(W_{\widetilde{d}}\) represent the hidden layer weight; \(b_{r}\), \(b_{z}\), \(b_{\widetilde{d}}\) are offset values, which are all parameters that need to be optimized for learning; : indicates point multiplication relation; \([d_{t-1},\widetilde{y}_{t-1}]\) represents the concatenation of the previous hidden state and the decoder input data; \(\sigma\) means activation function.  
Get the network prediction value \(\tilde{y}_{T+t}\) at the \(t\) moment:  
\[\widetilde{y}_{T+t}=F_{cd}(y_{1},y_{2},\ldots,y_{T})=g(d_{t},c_{t}), \tag{19}\]  
where \(g(\cdot)\) is a linear change; the softmax function is selected in this paper.
## 4 Key Parameters of Cavitating Jet
### Nozzle Geometry and Diameter  
As mentioned above, the vortex cavitation in the cavitating jet is an important phenomenon, and the nozzle geometry, especially nozzle outlet geometry, is one of the key factors of the aggressive intensity of the cavitating jet, as the vortex is strongly affected by the nozzle outlet geometry. Figure 20 shows a schematic diagram of nozzle outlet geometry and the relative aggressive intensity of the cavitating jet from data published in previous reports [28, 39, 75, 79]. Whereas a similar figure was introduced by [PERSON] [3], the data of nozzles K and L [28, 75] were added in Figure 20. Nozzles A-E in Figure 20 are conventional nozzles for a water jet, and nozzle F is the standard nozzle for a standard test method for the erosion of solid materials by a cavitating jet [15]. Nozzle G is the nozzle obtained by optimizing the outlet bore and length experimentally [74]. Nozzle I and J had a guide pipe and a cavitator, as these enhance the aggressive intensity by about two times [39]. When both the guide pipe and the cavitator were installed, the aggressive intensity became four times larger that of nozzle J [39]. For nozzle K, when water flow holes were made near nozzle outlet, the aggressive intensity improved by 34%. When a long guide pipe with holes and water flow holes near the nozzle outlet were installed for nozzle L [28], the aggressive intensity of its cavitating jet L was 2.5 times larger than that of nozzle J and nearly 60 times larger than that of conventional water jet nozzles, as shown in Figure 20. The effect of nozzle geometry was also discussed in [14]. Resonating nozzles were also proposed and investigated [105, 106].  
The other important factor regarding nozzles is nozzle size. As mentioned above, vortex cavitation is an important phenomenon in the cavitating jet. In view of the Reynolds number, which is a key parameter of vortical flow, the larger velocity and the larger size are effective for the cavitating jet. However, too high a speed, i.e., too high an injection pressure, decreases the aggressive intensity of the cavitating jet, as shown in Figure 14b, as the sound velocity is decreased at too low a cavitation number, i.e., too-high speed condition. Thus, in the case of practical applications of the cavitating jet, the cavitating jet using a large nozzle at a relatively low injection pressure is better than that of a small nozzle at a high injection pressure [80]. The scaling law of nozzle size on the aggressive intensity of the cavitating jet is discussed in reference [107].  
Figure 20: Effect of nozzle outlet geometry on aggressive intensity of cavitating jet.
# Low Power Wide Area Network, Cognitive Radio and the Internet of Things: Potentials for Integration
## 5 Integrating Cognitive Radio in LPWAN for the Internet of Things
### CR-LPWAN at the PHY Layer
We suggest that LNAs be deployed to ensure that low power consumption rates are maintained to maximize the battery lifetime of CR-LPWAN systems. 4. **Filtering and Down Conversion**: The front-end of the CR-LPWAN system filters and down-converts the signal frequencies to their intermediate frequencies (IF). It achieves this by using a mixer to obtain the in-phase and quadrature signal components at the IF. It can then process the signal either at both the IF and baseband levels to minimize design complexities in CR-LPWAN systems. 5. **Analogue to Digital Converter**: The ADC transforms the analogue signal to its digital form. As an example, CR-LPWAN systems can be deployed with sigma delta ADCs to convert the input data and then all subsequent signal processing and demodulation processes can be performed in the digital domain. 6. **Fast Fourier Transform Module**: CR-LPWAN systems will adopt an FFT module to compute the signal's input energy. For example, an FFT LogiCORE IP core module can be used in this regard since it implements the Cooley-Tukey FFT algorithm in an efficient manner [80]. 7. **Threshold Estimator:** Most CR-LPWAN systems will be required to compute threshold values for accurate signal detection. Since this process often depends on the noise floor, simple threshold estimation techniques can be considered in CR-LPWAN systems such as the fixed threshold technique. However, while the fixed threshold technique is readily deployed in most LPWANsystems, e.g., LoRa [66; 81; 82], other approaches can be used such as the peak and average threshold mode techniques. In the peak threshold mode, the threshold level corresponds to the peak value of the received signal strength (RSS). In the absence of an input signal, or during the reception of zero bits, the acquired peak value is decremented until it reaches the noise floor threshold [83]. On the other hand, the average threshold mode simply computes the mean of the entire dataset supplied by the RSS block. However, this approach may not be efficient in the presence of DC (direct current) encoded data. Summarily, it is worth noting that appropriate configuration of threshold values is fundamental to the success of CR-LPWAN systems, and its choice may be application dependent. The decision module refers to a comparator, which can be used to determine the presence or absence of PU signals in the input band. Other functions such as modulation/demodulation are applicable based on existing brands such as LoRa, Sigfox, or Weightless. Summarily, the somewhat generic framework of Figure 3 can be leveraged to develop CR-LPWAN systems alongside an appropriate choice of the CRN scheme. Other PHY layer functions that can be executed within the LPWAN framework in the CR-LPWAN system are shown in Figure 4. These are known functions, which are often developed for use in most proprietary LPWAN technologies, for example, in the SX1276 LoRa architecture [83].
# Plasmonics in the Ultraviolet with Aluminum, Gallium, Magnesium and Rhodium
## 6 Conclusions  
UV plasmonics constitutes a new focus of research due to new challenges arising in fields such as biology, chemistry or spectroscopy. In our quest to find suitable metals for the UV range, we have analyzed recent work developed for four metals that present plasmonic behavior in this spectral region: aluminum, magnesium, gallium and rhodium. These metals have been classified into two categories: those with high oxidation tendency (Al and Mg) and those with low oxidation tendency (Ga and Rh).  
Figure 5: (a) Logarithmic scale \(|E|^{2}\) maps at E = 3.82 eV (\(\lambda\) = 325 nm, HeCd laser), (b) maximum near-field enhancement at the center of the gap and (c) spectral absorption cross-section Cabs for tripod star (left) and nanocubes (right) dimers of several gaps, varying from 1 to 10 nm, illuminated under normal incidence with polarization parallel to the dimer axis.  
By comparing the plasmonic response of small NPs (sizes smaller than 10 nm) made of these metals with their corresponding oxide layers, it can be concluded that the plasmonic performance of Al and Mg NPs is strongly affected by an oxide layer. This weakens their absorption efficiency and near-field enhancement. This effect is less noticeable as the size of the particle increases, specially for Al, which forms a self-terminating oxide shell. Recently, Rh, an oxide-free metal, has drawn the attention because it enhances its already favorable catalytic activity by UV illumination near its plasmonic resonance. From the experimental point of view, two geometries can be chemically synthesized: tripod stars and nanocubes. Rhodium NPs have shown the best UV plasmonic performance as compared with the other metals (highest values of absorption cross-section and near-field enhancement, specially on those geometries with edges and corners). In this review, we have also analyzed cooperative effects on dimers of Rh nanoparticles for those two geometries.  
This research has been supported by MICINN (Spanish Ministry of Science and Innovation, project FIS2013-45854-P) and sponsored by the Army Research Laboratory and was accomplished under Cooperative Agreement Number W911 NF-17-2-0023. [PERSON] wants to thank the University of Cantabria for her FPU grant. [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] conceived the original idea. [PERSON] and [PERSON] carried out numerical calculations. [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] analyzed the results and figures. [PERSON] wrote the paper. [PERSON] supervised the study. All authors reviewed the manuscript. The authors declare no conflict of interest.
## 6 Security Solutions
### End Device Security
#### 6.1.2 Secure Bootstrap  
A secure boot routine [110] can prevent malicious applications from loading during the system start-up process. A secure boot routine is a piece of code that can detect any modification in the operating system and system software during the start-up phase. Thus, a secure boot routine can ensure system integrity and bring the system to a known and trusted state. The bootstrap code is stored in the flash memory, such as NOR or NAND flash, and is executed directly from there. This ROM-based execution approach prevents an adversary from perceiving the bootstrap process. The complete bootstrap solution consists of additional security features, including a software update routine which receives and integrates new code and libraries to upgrade the system to a new version of the software image.
## 3 Experimental Results and Discussion
### Heat Flow  
Figure 6 describes the heat flow as a function of age for four different composites. In general, as the MWCNTs were added, the cumulative heat of the composites tended to decrease slightly compared with the plain cement paste. The cumulative heat decreased with the increasing amount of powder MWCNTs because the heat generated during hydration was released by the MWCNTs. However, the reduced heat was approximately 4-12 Joule/g, denoting no significant difference, and there was no effect of the MWCNTs on the strength due to their chemical reactions in the composites.