esa-sceva/satcom-chunk-collection huggingface dataset:
## 3 Overview of the VLC-IoT Paradigm
### VLC: An Overview  
Currently, LED lights are widely spread in our daily life. In addition, the IEEE 802.15.7 group recently issued a draft standard on OWC based on the progress in actual research regarding the improvement at the physical and data link layers of the performance of LED-based VLC. Moreover, VLC is defined in IEEE 802.15.7-2011 [IEEE_802.15.7-2011] as one of the communication solutions for meeting specific communication challenges using visible light. For example, some industry areas may be subject to limited RF communication environments, such as factories, mines, or underground facilities. In such environments, a dedicated communication technology is required [11]. The choice of VLC as a physical media support for IoT communication is due to several factors among them the network scalability, the interference mitigation, and the RF frequency bands scarcity. Moreover, VLC offers no interference to existing RF-based communications with the main advantage of being not subject to a license to use the spectrum of visible light. Additionally, VLC provides  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Ref.** & **Year** & **Applied** & \begin{tabular}{c} **Proposed a** \\ **VLC Design/** \\ **Architecture** \\ \end{tabular} & \begin{tabular}{c} **Reviewed** \\ **prospects and** \\ **Approaches** \\ **of VLC** \\ **of VLC** \\ \end{tabular} & \begin{tabular}{c} **Reviewed** \\ **VLC-IoT** \\ **Challenges** \\ \end{tabular} & \
\begin{tabular}{c} **Offered** \\ **Solutions to** \\ **Challenges** \\ \end{tabular} &
\begin{tabular}{c} **Identified** \\ **Future** \\ **Research** \\ **Directions** \\ \end{tabular} \\ \hline
[1] & 2015 & VLC systems & ✓ & X & X & X & X \\ \hline
[5] & 2016 & IoT & ✓ & X & X & X \\ \hline
[9] & 2016 & IoT & ✓ & X & X & X & X \\ \hline
[18] & 2018 & VLC systems & ✓ & ✓ & X & X & X \\ \hline
[28] & 2019 & 5G, IoT & ✓ & ✓ & X & X & X \\ \hline
[3] & 2019 & IoT, LS & ✓ & ✓ & ✓ & X & X \\ \hline
[4] & 2020 & V2V, LiFi & ✓ & ✓ & ✓ & X & X \\ \hline
[26] & 2020 & 6G & ✓ & ✓ & ✓ & X & ✓ \\ \hline
[27] & 2020 &
\begin{tabular}{c} Industrial \\ application \\ \end{tabular} & ✓ & ✓ & ✓ & X & ✓ \\ \hline
[10] & 2020 & OIoT & ✓ & ✓ & ✓ & X & X \\ \hline This paper & 202x & IoT & ✓ & ✓ & ✓ & ✓ & ✓ \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of this paper with related works.  
accurate location-based communication, in contrast to existing low-power communication, such as Bluetooth low energy (BLE) and near-field communication technologies [27].
# Towards Secure Searchable Electronic Health Records Using Consortium Blockchain
## 3 System Model
### System Model Design
#### 3.3.1 Phase 1: Registration Process  
In this phase, firstly, before seeing a doctor, patients must register with the hospital's blockchain network, and the system manager provides the patient with an Ethereum address which is unique and is equal to the visit cards of patients. Secondly, the system manager produces the pair key (public key, private key) for the patient and the doctor. Thirdly, the system manager generates new keywords from the key server.  
In this step, the preparation of the data samples was made by registering the patients, doctors, and data users (third parties) to produce the blockchain accounts for them. We use four entities in the system: medical service provider (doctor), system manager, data owner (patient) and finally data users (third parties). In this paper, the public key encryption with conjunctive keyword search features are used to permit any third party to search a document containing several keywords while using an encryption public key. This phase runs as follows.  
* _KeyGen(\(\lambda\))_: a security parameter \(\lambda\) as an input and a pair of the public and private keys (_Sk,Pk_) as an output for a given doctor and patients;
* _PEKS_ (_Pkpi_, \(\omega\)_)_: a patient public key _Pkpi_ and a selected set of keywords \(\omega\) = (\(\omega_{1}\),..., \(\omega_{n}\)) as inputs. The public key of the patient to generate a searchable encryption \(\omega\) for \(\omega\);
* _Trapdoor_ (_Skpi_, \(\mathcal{Q}\)_)_: The private key of a patient _Skpi_ and the keyword query Q = (\(\Omega_{1}\),..., \(\Omega_{n}\)) as inputs. The trapdoor \(T_{\mathbb{Q}}\) is computed for the conjunctive search of a possible keyword query;
* _KeyRenew_ (\(\omega\),\(e\))_: Each key server _Ksi_ (here 2 \([1;n]\)) can update its secret share without affecting the secret shared by all key servers to produce a new keyword \(\hat{\omega}\). It needs to be executed only once in an epoch (A period, often known as an epoch, is a definite and predetermined time frame).
## 7 Future Application: The Hydrogen Case  
The use of hydrogen as an energy carrier is a very topical issue, because it allows meeting, together with the use of fuel cells, the requirements of zero local emissions. One aspect that limits the diffusion on a large scale of hydrogen is its low volumetric energy density. Pure hydrogen reaches acceptable storage densities only at cryogenic temperatures, at \(-253\)\({}^{\circ}\)C, at high pressure, or both at high pressure and low temperature. The solution with the higher level of technology maturity is the storage at high pressure, at the same pressure levels considered for LNG.  
In considering the loading and unloading processes of hydrogen, it must also be taken into account that the energy density of H\({}_{2}\) is much less dependent on temperature than that of methane, as shown in Figure 21. Moreover, the compressor efficiency changes with molecular weight, in particular with the volumetric ones. It is mainly due to the valve loss power, which is lower with low molecular weight. For example, as reported in [21], the maximum adiabatic efficiency drops from 93% with CH\({}_{4}\) to a still very good 88% with H\({}_{2}\) at a compression ratio of 3 but from 91% to 70% at a compression ratio of 1.4.  
Simulations carried out with H\({}_{2}\) on the same plant considered for the loading and unloading of CNG show that the temperature reached at the end of the loading is much higher, as can be seen comparing Figure 7 with Figure 22, with reference to the adiabatic case. In addition, the maximum required compressor power becomes higher and exceeds the maximum design value of 10 MW, as shown in Figure 23.  
Figure 21: Energy density of CH\({}_{4}\) vs. H\({}_{2}\).  
Figure 22: Pressure vessels conditions (H\({}_{2}\) loading).  
Taking into account the entire process, the specific energy consumption is almost ten times higher than that of methane, as reported in Table 4.
## 4 Case Study
### Determination of System Parameters  
The first step consists of determining the parameters of the system in Equation (11), which are uniquely determined when the system is fixed. A calibration board is fixed on the wall as shown in Figure 13--each grid size \(L\) is a standard of 1 cm, and the average length of all grids of the calibration board is set as the target. the measuring system in Figure 3 is used to capture the calibration board vertically from 2 to 36 m, and the distance from the system to the calibration board by laser rangefinder is recorded. In order to check the variability of the distances measured by the laser rangefinder, two sets of data are obtained by two operators separately. The basic parameters \(f\) is 0.2 m, and \(U\) is the measured value; the unit pixel size is 4.4 \(\times\) 10\({}^{-6}\) m, and the unit pixel aspect ratio is set as 1 as expressed in the camera manual. The parameters X and Y are calculated as 1.1306 and 1.1421 by the least squares method, respectively. Another 34 images of the calibration board are measured as two test groups, and the results are presented in Figure 14. It can be seen that after correcting the parameters, the measurement results are concentrated near the true value. However, some fluctuations occur in the measurement range more than 30 m, which could  
Figure 11: The HICHANCE-CK103 crack width measuring instrument for verification.  
Figure 12: Accuracy verification results of the adopted crack width measuring instrument: (**a**) crack scale board with several standard widths; (**b**) measurement results for standard widths.  
Note that the system parameter tests were confirmed before practical application, and the camera parameters (such as focal length) and measurement setup can be adjusted for different circumstances. Because the base line distance \(BL\) is about 20 cm and much less than the measured distance \(U\), as stated in Section 3.1.2, the value of \(BL\) is ignored in the following experiment.
## 3 Results and Analysis
### Geothermal Characteristics of Lushan Geothermal Springs
#### 3.1.4. Recharge, Runoff, and Discharge of Geothermal Water  
According to the study of hydrogen and oxygen isotopes of geothermal water, most geothermal water is recharged by local precipitation. The water quality analysis data of hot spring also shows that it is mainly recharged by atmospheric precipitation. The atmospheric precipitation infiltrates along the structural fracture or fracture zone, passes through deep circulation heating, and then rises along the fracture channel, forming local geothermal anomaly or overflowing the surface to form hot spring. Its recharge, runoff, storage, and discharge conditions are strictly controlled by the fault structure. The five hot springs have sufficient supply sources, good heat storage permeability and strong runoff, for example, the self-flow of the boreholes in Shangtang is up to 137.29 m\({}^{3}\)/h, and the maximum water head is 15.58 m higher than the ground. All hot springs contain the same ions, and the content of each ion is relatively close, indicating that they have similar recharge sources, runoff and discharge channels, and have certain hydraulic connection [41].
## 4 Results and Discussion
### Evaluation Metrics
#### 4.4.3 Mean Square Error (MSE)  
The MSE is described as the mean squared error between actual values and expected outcomes, and it is computed using Equation (38).
## 2 Materials and Methods
### Simulation Setup  
The simulations of the proposed frequency reconfigurable antenna were performed using Higher Frequency Structural Simulator (HFSS). For frequency reconfigurability two RF PIN diodes \(D_{1}\) and \(D_{2}\) (Infineon, model # BAR50-02) were utilized. Two capacitors \(C_{1}\) and \(C_{2}\) were used to connect the pads with the radiator physically and to block current flow from biasing pads to the radiator. Capacitor \(C_{DC}\) is utilized to stop the flow of current toward the connector which may affect the performance of the antenna. The pads for diode are connected using a vias to biasing pads presented at the backside of the antenna, as depicted in Figure 1b. Inductor \(I\) is employed to stop the unwanted RF-current from the source VDC. The biasing voltage is provided from the backside of the antenna to mitigate the effects of DC-wires on the performance of the antenna.
# A Dependable Localization Algorithm for Survivable Belt-Type Sensor Networks
## 1 Introduction
However, there are relatively few studies on algorithms which are suitable for special environments such as belt-type, crossover, and annular areas. For special occasions, the node deployment and positioning requirements are different compared with open flat space [22; 23]. Generally, any kind of security algorithm will consume part of the available resources, including the computing energy and communication costs. Therefore, for a specific positioning system, we need to consider the system application background, security requirements of attack models, resource conditions and other factors [24; 25]. Since special node deployments have different effects on network connectivity, many existing algorithms are greatly limited by their capacity [26; 27; 28; 29; 30; 31; 32]. The motivation of this paper is that the nodes cannot always achieve correct and stable positioning information, which may trigger network security risk. In particular, the wireless transmission medium is susceptible to temperature, humidity and other environmental impacts. Any failures or errors may generate unpredictable security risks. In this scenario, the node location method which is applicable for the wide area cannot be used directly in the long zone. At the same time, the resources of a single node are limited and it is difficult to add additional devices for positioning. In this paper, we fully consider the special structure of the region to deploy the belt-type sensor networks. More importantly, the addition of extra hardware devices is avoided and the network infrastructure is utilized as much as possible to locate the target. If the non-ranging method is used directly, the positioning accuracy cannot meet the requirements well. In order to get more precise results, an iterative refinement mathematical treatment method is introduced during the process. The limited resource of a single node is an important prerequisite, which has been fully considered. For the contradiction between energy consumption and positioning accuracy, an acceptable balance is established. We make the following contributions:1. We design a node deployment mechanism that could effectively save energy. 2. A hop-distance calculation method that can eliminate blurring is proposed. 3. We improve the accuracy of the proposed algorithm. The remainder of our paper is organized as follows: Section 2 presents the modeling of the belt-type topology and node deployment mechanism based on energy-efficiency. Section 3 describes the improvement measures of the proposed algorithm in different stages from three aspects. How to determine the security of location information is also discussed in this section. Section 4 illustrates our simulations and experimental results. Finally, the conclusions are presented in Section 5.
## 2 Materials and Methods  
According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement (PRISMA) criteria [11], a systematic literature search was performed on PubMed, Scopus, and ISI Web of Science databases. The search aimed to identify studies focusing on epigenetic effects induced by formaldehyde exposure published until the 1 st of November 2019 (Figure 1). The terms \"formaldehyde,\" \"exposure,\" \"epigenetic,\" combined with the Boolean operator \"AND,\" were employed to assess the exposure context and the outcome of the investigation. All titles and abstracts retrieved were independently examined by two of the authors who selected articles that met the inclusion criteria. Peer-reviewed research articles, i.e., cross-sectional, cohort, case-control studies, published in English and exploring epigenetic alterations determined by FA exposure in humans have been included together with studies performed on animal and cellular models. Exclusion criteria regarded articles published in languages other than English, papers exploring epigenetic effects of endogenous FA, studies carried out on experimental models different from cells, animals and human subjects, review and conference papers, as well as publications not addressing the possible relationship between FA exposure and epigenetic effects. Our preliminary search retrieved 13, 25, and 15 references through PubMed, Scopus, and ISI Web of Science databases, respectively, for a total of 53 articles. After duplicate removal, 29 articles remained. Among those, the studies that did not meet the inclusion criteria were excluded and specifically, 17 were removed because they were considered out of the topic from title and abstract analysis, 5 were excluded as review articles, and 1 as performed in experimental settings different from those considered suitable for inclusion. Indeed, 6 publications could be identified in this preliminary phase. Therefore, an extended search, including the following terms: \"formaldehyde exposure,\" individually combined with \"DNA methylation,\" \"histone,\" and \"microRNA,\" was performed and could retrieve the above mentioned papers. Four further eligible articles could be included through the assessment of the reference list accompanying published articles and implement the pool of relevant publications found via the electronic search. All full texts of the articles considered valuable for the aim of our review have been obtained and a critical evaluation was performed. Overall, our search retrieved a total of 10 publications for review.
# Photodynamic Inactivation of Human Coronaviruses
## 3 Results  
### Measurement of Phototoxic Threshold of PhytoQuin in Huh7.5 Cells and BHK-21 Cells  
Photodynamic inactivation (PDI) employs a photosensitizer (PS), light, and oxygen to create a local burst of reactive oxygen species (ROS) that inactivate microbes. For our experiments to investigate the PDI of human coronaviruses, we employed a PS, PhytoQuin, which is an extract from _Polygonum cuspidatum_ (common name: Japanese Knotweed) prepared by PhotoDynamic, Inc. We began by evaluating cell viability with and without light exposure following treatment with PhytoQuin or the solvent, dimethyl sulfoxide (DMSO). We chose Huh7.5 (human hepatocellular carcinoma) cells and baby hamster kidney-21 (BHK-21) cells for these analyses because they are susceptible to infection by HCoV-229E and HCoV-OC43, respectively.  
To establish the phototoxic threshold concentrations of PhytoQuin, Huh7.5 cells were treated with PhytoQuin or vehicle control at room temperature with exposure to LED light (49 J/cm\({}^{2}\) or 98 J/cm\({}^{2}\)) or protected from light followed by culture at 37 \({}^{\circ}\)C for 48 h. DMSO concentrations above 2% were toxic to Huh7.5 cells where no additional toxicity was observed with either light treatment (Figure 1A). The 50% cytotoxic concentration (CC\({}_{50}\)) of PhytoQuin in Huh7.5 cells was 10 \(\upmu\)g/mL at 49 J/cm\({}^{2}\) of photoactivation and 4 \(\upmu\)g/mL after 98 J/cm\({}^{2}\) of photoactivation (Figure 1A). PhytoQuin was less toxic in the absence of photoactivation (\"Dark\"), with a CC\({}_{50}\) of 17 \(\upmu\)g/mL. BHK-21 cells behaved similarly with DMSO treatment, with no cytotoxicity up to the highest concentration tested (0.8%; Figure 1B). While only 49 J/cm\({}^{2}\) of light exposure was tested using BHK-21 cells, cytotoxicity was only observed with PhytoQuin concentrations of 78 \(\upmu\)g/mL, suggesting that the BHK-21 cells are more resistant to transient ROS-mediated damage than Huh7.5 cells (Figure 1B). Altogether, these experiments demonstrate the low cytotoxicity of PhytoQuin in these human cell lines. A concentration of 4 \(\upmu\)g/mL PhytoQuin (equivalent to 0.5% DMSO, indicated by the vertical dashed lines in Figure 1) was selected as the maximal dose used in all subsequent infection experiments, which falls well below the CC\({}_{50}\) value for both cell lines.
# Enzymatic Synthesis of Biobased Polyesters and Polyamides
## 8 Lipase-Catalyzed Synthesis of Sustainable Polyesters and Polyamides from Biobased Monomers
### Biobased Saturated Aliphatic Polyesters
#### 8.1.3 Other Biobased Aliphatic Polyesters  
Many other (potential) biobased aliphatic polyesters are synthesized via lipase-catalyzed polycondensation. Some examples are discussed as follows.  
The lipase-catalyzed solvent-free polycondensation of aliphatic diacids (C2-C12) and aliphatic diols (C2-C12) was performed by [PERSON] et al. [253] The enzymatic polymerization yielded various aliphatic polyesters with \(\overline{M_{\text{m}}}\)'s and dispersities of around 1300-14,000 g/mol, and 1.1-2.3, respectively.  
Biodegradable \(\varco\)-polyesters containing malic acid units were synthesized via the N435-catalyzed polycondensation of adipic acid and 1,8-octanediol with l-malic acid, a natural occurring monomer (Scheme 27) [254]. The solvent-free enzymatic polycondensation gave poly(octamethylene adipate-\(\varco\)-malate), with \(\overline{M_{\text{w}}}\)'s, dispersities and reaction yields of 4700-9500 g/mol, 1.50-1.92, and 88-96%, respectively.  
The lipase-catalyzed polymerization of aliphatic diacid ethyl esters (C2, C4 and C8) and diols (C4, C6 and C8) were performed in bulk or by using \(\beta\)-cyclodextrinrin as the support architecture. Various saturated aliphatic polyesters were produced, with \(\overline{M_{\text{w}}}\)'s ranging from 5300 to 44,600 g/mol [255,256].  
Recently, we succeeded in preparing a series of (potentially) biobased poly(butylene dicarboxylate)s via the N435-catalyzed polycondensation of 1,4-butanediol and diacid ethyl esters differing in chain length (C2, C3, C4, C6, C8 and C10) (Scheme 28) [257]. High molecular weight poly(butylene dicarboxylate)s were obtained, with \(\overline{M_{\text{w}}}\)'s of up to 94,000 g/mol. We found that increasing the chain length of diacid ethyl ester from C2 to C4 resulted in poly(butylene dicarboxylate)s of significant higher molecular weights; however, upon further increasing the chain length from C4 to C10, poly(butylene dicarboxylate)s with lower molecular weights were obtained. Meanwhile, the enzymatic polymerization with diethyl succinate (C2) gave the lowest molecular weight products. This suggested that CALB possesses a higher selectivity towards diacid ethyl esters with a >C2 chain length; and CALB prefers diethyl adipate (C4) over the other tested counterparts.  
Moreover, biobased telechelic polyesters were produced via N435-catalyzed polycondensation of azelaic acid and 1,6-HDO with different functional end-cappers in supercritical CO\({}_{2}\)[258]. The \(\overline{M_{\text{m}}}\)dispersion and reaction yield of the resulting telechelic poly(hexamethylene azelate)s were around 1500-2400 g/mol, 1.73-2.18, and 78%-88%, respectively. The obtained telechelic polyesters can be further modified by cross-linking or by chain extension reactions.