esa-sceva/satcom-chunk-collection huggingface dataset:
## 6 Conclusions and Future Work  
This paper presented and discussed a novel practical digital TV antenna that is suitable for indoor environments. The antenna can be placed on a wall, for example, since it is very thin--about 6.8 mm including the aluminum foil. The upper dielectric is composed of FR4 with thickness \(h_{s}=1.6\) mm, relative permittivity \(\varepsilon_{r}=4.1\), and tan\(\delta\) = 0.015\(\delta\)1 GHz. The lower dielectric is composed of air, with thickness \(h_{a}=3.2\) mm and relative permittivity equal to unity. The designed antenna has gain of 10.5 dBi, efficiency of 92%, and bandwidth of 25 MHz at the 10 dB return loss level. The proposed antenna overcomes the narrowband characteristics of common microstrip antennas, is mechanically robust, and can be connected to a coaxial cable without requiring any extra electronic components or devices such as baluns.  
Figure 8: S\({}_{11}\) measurements in Smith chart.  
Figure 7: Simulated and measured radiation patterns. (**a**) \(\phi\) = 90\({}^{\circ}\); (**b**) \(\phi\) = 0\({}^{\circ}\).  
The proposed antenna has huge potential to be replicated and rearranged in an array. By adding electronic control to such an array, it is possible to perform smart beamforming in the azimuth plane, enabling new functionalities for DTV. An array of such antennas is quite useful for reducing self-interference caused by secondary transmitters in a single-frequency network (SFN) configuration. The antenna can also be spatially replicated to cover other applications in 5G broadcasting environments [14]. Another advantage of our proposed antenna is its bandwidth of 25 MHz, avoiding interference in the frequency domain. Although the antenna dimensions may seem large (67.3 by 27.0 cm), the experimental demonstration presented here proved the main concept. Further reduction in the dimensions can be achieved by using reflectors or metamaterials with magnetic response, which is reserved for future work. This antenna can be used to receive any modern digital TV signals such as those specified in DVB-T/T2, ISDB-T, or ATSC standards.  
Antenna research and design, A.N., P.M., T.V., and J.M.; simulation, P.M. and T.V., theoretical formulation, J.M. and S.M.; laboratory and field tests, A.N. and P.M.; methodology, A.N. and J.M.; writing, A.N., T.V., J.M., and S.M.; writing--review and editing, A.N. and J.M.; coordination, A.N. All authors have read and agreed to the published version of the manuscript.  
This work is funded by FCT/MCTES through national funds and when applicable cofunded EU funds under the project UIDB/50008/2020-UIDP/50008/2020.  
The authors declare no conflict of interest.
# An Experimental Study on the Formation of Spatial Cognitive Maps in Humans
## 1 Introduction
However, a larger number of objects might degrade those representations by elevating the cognitive load: more object-location bindings must be maintained in spatial memory, straining capacity and increasing the risk of interference. Indeed, the extant literature on human working memory documents that a larger number of items is more difficult to remember [20; 21]. This \"set-size effect\" has also been documented in a wayfinding study [22]. Notably, however, participants in the latter study were asked to repeatedly follow a fixed route, a task that requires serial-order memory and associative memory [23] but not the use of a cognitive map. Whether there exists a set-size effect for cognitive maps, therefore, is still unknown and is investigated in this study by comparing participants' performance in two environments containing a different number of objects. The third purpose was to find out whether the speed of cognitive map formation (locally abrupt vs. gradual) and its set-size effect depend on the perspective from which spatial knowledge is acquired during learning trials. Several studies [24; 25; 26] have compared two encoding conditions. In one, participants walked or were passively transported through the environment and thus encoded spatial information from a first-person perspective; in the other condition, they inspected a cartographic map and thus encoded spatial information from a survey perspective. These studies reported that encoding from a first-person perspective resulted in better performance on tests based on a first-person perspective (judgments of path length and heading from one's current position to an object) compared to tests based on a survey perspective (judgments of straight-line distances and directions between object pairs), while the opposite was the case for encoding from a survey perspective. These findings suggest that the encoding perspective can have an impact on the quality of spatial representations; it therefore may also influence the speed at which cognitive maps emerge (abruptly vs. gradually) and the impact of the number of objects on the formation of those maps. Specifically, if spatial information is encoded from a first-person perspective, it must be transformed into a survey perspective to form a cognitive map, taking into account one's own varying position as signaled by visual, kinesthetic, and other self-motion cues (\"path integration\"; [27]). In contrast, if spatial information is encoded from a survey perspective, no such transformation is needed. Thus, the additional processing demand of first-person encoding may slow down map formation and height vulnerability to overload by an increasing number of item-location bindings. In sum, this study examined (1) whether the formation of cognitive maps is locally abrupt or gradual, (2) whether it is affected by the number of objects (set-size effect), and (3) whether both the emergence speed and the set-size effect vary with the spatial encoding perspective.
## 4 Conclusions  
Fine particle peening (FPP) using hydroxyapatite (HAp) shot particles was performed to improve the fatigue strength and form a HAp transfer layer on a beta titanium alloy (Ti-22V-4 Al). Rotating bending fatigue tests were performed to investigate the effect of FPP on the fatigue properties. The results obtained are summarized as follows:  
1. FPP using HAp shot particles can form a HAp layer on the surface of the Ti-22V-4 Al alloy.  
2. FPP using HAp shot particles increases the fatigue strength at 10\({}^{7}\) cycles and the fatigue life of the Ti-22V-4 Al alloy due to the formation of a work-hardened layer with compressive residual stress on the surface of the Ti-22V-4 Al alloy.  
3. There is no improvement of fatigue life by FPP at high stress levels greater than 700 MPa, whereas at low stress levels lower than 700 MPa, the fatigue life of FPP-treated specimens was improved by FPP. This is due to work hardening and generation of high compressive residual stress by FPP.  
4. The fracture mode of FPP-treated specimens shifted from surface-initiated fracture to subsurface-initiated fracture at a stress level of 600 MPa. FPP-treated specimens showed different failure modes at high and low stress levels.  
Conceptualization and methodology, Y.N. and S.K.; formal analysis, Y.N.; investigation, Y.N., K.N. and T.S.; resources, T.A.; writing--original draft preparation, Y.N.; writing--review and editing, K.N., T.A., T.S. and S.K.; supervision, Y.N. and S.K.; funding acquisition, Y.N. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Japan Society for the Promotion of Science, Japan, grant number 16K17986, and the Naito Science and Engineering Foundation.  
Not applicable.  
The beta titanium alloy (Ti-22V-4 Al) used in this research was supplied by Diado Steel Co., Ltd. FPP treatment was conducted on the basis of the Japanese patent (No. 3314070) applied by Fuji Kihan Co., Ltd., and the Aichi Center for Industry and Science Technology.  
The authors declare no conflict of interest.
# Pilot-Assisted OFDM for Underwater Acoustic Communication
## 3 System Architecture
### Linear Equalization
#### 3.2.2 Zero Forcing (ZF)  
Assuming a perfect knowledge of the channel in terms of \(H_{k}\), i.e., the channel transfer function for the \(k\)th OFDM symbol, the equalized sequence \(\widetilde{C}_{k}\) is given by:  
\[\widetilde{C}_{k}=\frac{H_{k}^{*}}{|H_{k}|^{2}}\;\hat{\mathcal{C}}_{k}=C_{k}+ \frac{H_{k}^{*}}{|H_{k}|^{2}}\;n_{k}. \tag{11}\]  
In this equation, \(n_{k}\) represents the AWGN added to the \(k\)th OFDM symbol and \({}^{*}\) represents the conjugate.
# An Effective Blockchain-Based Defense Model for Organizations against Vishing Attacks
## 3 Preventing Social Engineering Attacks Using Security Principle
### Model Components  
The proposed model encompasses several units:  
* Recipient (front-desk): is a representative who answers all incoming calls from outside the company. Their role is to provide information about the caller's requests if they know the answer. The recipient knows public information. If they do not possess the knowledge, they will ask the information from other employees. The recipient does not know anything considered secret about the organization's data and is not permitted to make any transactions.
* Social engineer (caller): is an external caller wishing to obtain sensitive information or make illegal transactions, such as changing bank account-associated phone numbers.
* Background verifications: are performed by any number of individuals to ensure that the transaction complies with the organization's security regulations. They receive any requests for information or certain transactions made by the recipient. If they suspect the query, they reject it and notify the recipient about a possible SE attack. If all background verifiers confirm the transaction's validity, the transaction is registered and saved in a blockchain. Then, the recipient can deliver the information or transfer the caller to the requested service.
* Blockchain: is the data structure that enables decentralized registration of transactions requested through phone calls. The main goal of using blockchain is to create a new block when all involved parties agree to a transaction: no one can individually decide without others knowing about it. No transaction will be made before creating the new block that records the transaction endorsed by the involved parties. The blockchain manages the endorsement process and resolves the synchronization issues. It implements dual control security principles.
* Blockchain owner: is any organization interested in installing a secure mechanism to avoid social attacks by phone, especially within the banking sector. The blockchain owner is responsible for implementing the various policies, such as assigning permissions to allowed agents that check for a potential SE attack. Those checkers could have the same or different sensitive data according to the organization's policies.
* Key management system: generates access keys used to access the private blockchain. In addition, the keys are used to create the new blocks. A new block will only be formed when it is endorsed by all the parties involved, using their keys during the verification process. The key management system is generally incorporated within the blockchain platforms. In this way, the organization can implement a blockchain network and access management systems from scratch or reuse and adapt existing platforms, such as the hyperledger fabric blockchain network.
## 4 Discussion
The value ascertained experimentally through our study approximates 10% v/v isopropanol, similarly lower than the calculated value just as the reported values are in Figure 5. It is notable that both the calculated and experimental values are starkly less than the boiling point azeotrope composition of 19% v/v isopropanol used by conservators with the expectation that constant composition evaporation will occur [8; 9; 10; 11; 12]. Utilizing the aforementioned methodology [22], estimations were also made for the 2-butanone in cyclohexane system. Figure 6 shows the derived data for T\({}_{\rm AZ}\) and P\({}_{\rm AZ}\). At ambient temperature, the calculated composition of the azeotrope ranges between 38.88 and 38.94% v/v 2-butanone, with an associated P\({}_{\rm AZ}\) spanning 107-121 mmHg. The  
Figure 4: Predicted T\({}_{\rm AZ}\) and P\({}_{\rm AZ}\) for the isopropanol and n-hexane system (gray dots and line) compared to some reported experimental values (black diamonds). Figure 5: Predicted x\({}_{\rm AZ}\) and T\({}_{\rm AZ}\) for the isopropanol and n-hexane system. value documented in the literature at boiling conditions (T\({}_{\rm AZ}\) 72 \({}^{\circ}\)C and P\({}_{\rm AZ}\) 760 mmHg) for this system is 40% v/v 2-butanone. Consequently, this azeotropic mixture does not exhibit significant pressure sensitivity, and the composition remains nearly invariant over a large range of pressures. Considering the empirical data and estimated azeotrope compositions, we revised the temperature-composition equilibrium schematics to clarify these observations. Figure 7 offers relevant illustrations of the systems under study. The equilibrium plots substantially aid in conceptualizing the influence of pressure on the azeotropic temperature and composition. In the instance of the isopropanol and n-hexane system (Figure 7A), the alteration in the vapor pressure of the mixture from 760 mmHg (i.e., under boiling conditions) to a vapor pressure of 135 mmHg at ambient temperature results in a shift in the azeotropic composition of approximately 7%. Conversely, the 2-butanone and cyclohexane system (Figure 7B) does not show a significant change in azeotropic composition within the 112 to 760 mmHg pressures range. Figure 6: Predicted T\({}_{\rm AZ}\) and P\({}_{\rm AZ}\) for 2-butanone and cyclohexane system. Figure 7: Schematic illustrations of temperature-composition equilibrium plots for binary systems: (**A**) isopropanol and n-hexane, and (**B**) 2-butanone and cyclohexane. Orange plots are for boiling points (760 mmHg), while blue plots represent room temperature conditions. Note the impact on azeotrope composition.
## 5 Conclusions  
In this work, the local DIC solution is supplemented with a fast post-processing algorithm to enforce the continuity of tractions across the interfaces of shear ruptures. This procedure allows us to obtain more physically meaningful stress fields near the interface, which is important when DIC is applied to study the dynamics of laboratory frictional ruptures. In the algorithm, the stresses near the interface are calculated from local polynomials that are constructed using a constrained inversion. This inversion is such that the resulting displacements match the displacements of pixels closer to the center of the subset, where the DIC solution is most accurate, while the resulting stresses satisfy traction continuity conditions at the interface.  
We applied the algorithm to the displacement fields of a laboratory shear rupture obtained with a local DIC procedure, to show that the algorithm indeed produces the desired continuous traction fields across the interface. A sensitivity study provided a constraint on the parameters \(n_{x2,inter}\), \(n_{x2,cont}\), and \(n_{x1}\) involved in the construction of the polynomials, such that undesired artifacts in the stress fields were eliminated. We found that parameter ranges of \(8\leq n_{x2,inter}\leq 14\) (1/5 to 1/3 of the subset size) and \(7\leq n_{x2,cont}\leq 15\) gave similar results, independent of the value of \(n_{x1}\). Relatively minor changes in displacement fields around the interface can produce non-negligible gradient changes, resulting in some non-uniqueness regarding the exact stress evolution towards the interface, even if the traction continuity is enforced. Future progress can be made by combining the results inferred by the analysis presented in this work with dynamic rupture modeling that matches the observed full fields. The dynamic solutions can then be interrogated for the spatial dependencies of stress fields next to the interface.  
The averaging procedure for stresses above and below the interface, employed in the previous study [1] to study friction, works well to mimic the traction continuity across the interface due to the special nature of this rupture problem that exhibits certain symmetries across the interface. However, the averaging procedure may not work as well in cases where the symmetries are disrupted, as in the case of ruptures approaching a free surface [27]. We will examine such cases in future studies.  
Conceptualization, Y.T., V.R., A.J.R., and N.L.; Methodology, Y.T.; Investigation, Y.T. and V.R.; Data curation, V.R.; Writing--original draft preparation, Y.T.; Writing--review and editing, V.R., A.J.R., and N.L.; Supervision, A.J.R. and N.L.  
This study was supported by the US National Science Foundation (NSF) (grant EAR-1651235), the US Geological Survey (USGS) (grant G16 AP00106), and the Southern California Earthquake Center (SCEC), contribution No. 18131. SCEC is funded by NSF Cooperative Agreement EAR-1033462 and USGS Cooperative Agreement G12 AC20038.  
We thank [PERSON] for fruitful discussions about the constrained inversion.  
The authors declare no conflict of interest.
# A Review on Anaerobic Digestion of Lignocellulosic Wastes: Pretreatments and Operational Conditions
## 2 Overview of AD Process
### Feedstock Degradation Pathway
#### 2.2.4 (d) Methanogenesis  
In this final step, acetonitrile and hydrogenotrophic methanogens (_Methanobacterium, Methanobrevibacterium, Methanoplanus, Methanospirillum, Methanosaeta, Methanosarcina_) work on converting acetate (by acetoclastic methanogens) and hydrogen and carbon dioxide (carbon dioxide-reducing and hydrogen-oxidizing methanogens) into methane and carbon dioxide. The larger portion of methane is derived from the conversion of acetate and the rest is primarily produced from H\({}_{2}\) and CO\({}_{2}\)[20]. Alternatively, hydrogen and carbon dioxide may be produced through syntrophic acetate oxidation coupled with hydrogenotrophic methanogenesis. Extended methane production can be conducted via the hydrogenotrophic pathway based on process characteristics [22; 23].  
Generally, maintaining a synchronized state between different degradation steps is crucial throughout the process and any fluctuation or decrease in the activity of one or several microbial groups could severely influence the process performance and efficiency, and could even lead to process failure.
# Internal Interface Diversification as a Security Measure in Sensor Networks +
## 2 Interface Diversification
### Attack Scenarios Mitigated by Diversification
#### 2.2.3 An Infected Update  
Internal interface diversification can be used to mitigate the threat of infected updates. The adversary can try to slip malicious code into a remote update at some point along the way. Of course, the remote updates are usually sent in encrypted form and possibly signed, but the keys might get compromised, or the adversary could find a way to tamper with the contents of the update before encryption. Paradoxically, this causes the updates often meant to improve the security of the system to become a potential security risk themselves. However, as long as the adversary does not know the diversification secret of a specific node or insert malicious code before the update is diversified, the harmful code slipped into the update does not work in a diversified system. Of course, if the attacker gets access to the diversified code, he or she can attempt to deduce its meaning and find out the results of the diversification that way. However, this method requires costly analysis, and the results can be used only in that one specific system.  
Of course, having diversification in place can make distributing updates to systems more challenging as the updates need to be compatible with the diversified system. This ties into the question of when the diversification should be performed. If the updates are received pre-diversified, the vendor delivering the updates needs to be aware of the diversification secret. If the updates are diversified on-device before they are applied, the system must pose a way to diversify, and subsequently run, undiversified binaries. Securing these pathways is critical to the security of the entire scheme: if an attacker can find a way to diversify untrusted binaries with the device-specific diversification secret, then he or she is able to run arbitrary code.
# A Through-Transmission Ultrasonic Method for the Detection of Ferrite Tile Defects
## 3 Numerical Modeling  
### Establishment of Simulation Model  
To assess the feasibility of ultrasonic detection for internal defects, this study employed COMSOL Multiphysics v.6 software for modeling the water-immersion ultrasonic inspection method [25; 26; 27; 28; 29]. In the physical field modeling, the pressure acoustics time-domain explicit physics interface was chosen for simulation modeling. The schematic representation of the overall simulation model is shown in Figure 2. Due to the symmetry of the entire model, the geometric model was set as an axisymmetric model to reduce computational time and memory requirements. The model was divided into three parts, namely, A, B, and C. Part A comprised the ultrasonic emission source and the coupling water layer. Part B represented the 3033 aluminum alloy test material with internal defects, with dimensions of 10 mm \(\times\) 42 mm. Part C consisted of the coupling agent layer and the ultrasonic wave receiving transducer. The coupling material was set as water, and the thickness of the coupling layer was set at 3.5 mm. The outer side of the transmission model is completely enclosed by the ideal absorbing layer to prevent the reflection phenomenon in the boundary of the local model, and the simulated sample domain and the coupling domain extend indefinitely in this direction.  
The excitation signal equation \(V_{0}\) was defined as follows:  
\[V_{0}=e^{(\frac{t-2t_{0}}{t_{0}/2})^{2}}sin(2\pi f_{0}t) \tag{8}\]  
where \(t_{0}\) is the period of the ultrasonic wave, and \(f_{0}\) is the frequency of the ultrasonic wave.  
The ultrasonic frequency was set at 10 MHz, and the defect diameter ranged from 0.1 mm to 1.2 mm. The simulation time step was set at 1/10 of the ultrasonic signal period, i.e., 0.2 us, to ensure sufficient sampling of the ultrasonic transmission signal.