esa-sceva/satcom-chunk-collection huggingface dataset:
# Study of an Atmospheric Refractivity Estimation from a Clutter Using Genetic Algorithm
###### Abstract  
In this paper, a method for estimating atmospheric refractivity from sea and land clutters is proposed. To estimate the atmospheric refractivity, clutter power spectrums based on an artificial tri-linear model are calculated using an Advanced Refractive Prediction System (AREPS) simulator. Then, the clutter power spectrums are again obtained based on the measured atmospheric refractivity data using the AREPS simulator. In actual operation, this spectrum from measured reflectivity can be replaced with real-time clutter spectrums collected from radars. A cost function for the genetic algorithm (GA) is then defined based on the difference between the two clutter power spectrums to predict the atmospheric refractivity using the artificial tri-linear model. The optimum variables of the tri-linear model are determined at a minimum cost in the GA process. The results demonstrate that atmospheric refractivity can be predicted using the proposed method from the clutter powers.  
radio propagation; radar; optimization algorithms; clutter images Article  
Study of an Atmospheric Refractivity Estimation from a Clutter Using Genetic Algorithm. _Appl. Sci._**1000**  
**2022**, 12, 8566. [[https://doi.org/10.3390/app12178566](https://doi.org/10.3390/app12178566)]([https://doi.org/10.3390/app12178566](https://doi.org/10.3390/app12178566))
## 2 Experimental Program
### Mix Proportions  
The eight optimized alkali-activated paste binders resulting from four binary/ternary combinations of SCMs, and two powder-based reagents' having two different dosages (from authors' research) were used to develop AAMs with a constant amount of silica sand [23]. The objective was to achieve fresh and rheological characteristics comparable to that of the control mortar (FP\({}_{\text{C}}\)M) previously established at Ryerson University for producing fiber-reinforced engineered cementitious composites (ECCs) [25,26]. The mix proportions for one-part AAMs and control mortar are presented in Table 2. The total fly ash content varied from 50 to 60%, and the amount of ground granulated blast furnace slag (GGBFS) varied from 40 to 50% by mass of the total binder content similar to the fly ash and cement content in the control mortar (Table 2). Two dosages/combinations of powder-based reagents were used. A constant amount of silica sand (0.3 of total binder content) was added to the binder when it obtained the desired fluidity. One of the objectives was to use these mortars to develop engineered AACs in further studies. Therefore, the quantity of sand (sand to binder ratio of 0.3) was kept similar to fiber reinforced engineered cementitious and geopolymer composites (ranging from 0.3 to 0.36) from authors and other existing studies [25, 26, 27] to ensure adequate matrix fracture and crack-tip toughness. Additionally, use of such low quantity sand will ensure adequate workability for the uniform dispersion of fibers responsible for strain hardening behavior [25, 26, 27]. The water to binder ratio varied from 0.35 to 0.375 to achieve a minimum slump flow diameter of 150 mm. The dosage of HRWRA was kept constant as it is acidic and should not act differently for varying mix compositions with alkaline reagents.  
The reagent component and the initial chemical ratios in the mix compositions are presented in Table 3. Reagent 1 has a reagent component ratio (calcium hydroxide to sodium metasilicate) of 1:2.5, while reagent 2 has a reagent component ratio (calcium hydroxide to sodium sulfate) of 2:5:1. The performed of these component ratios was superior in terms of compressive strength from authors' research on AABs [23]. The fundamental chemical ratios in terms of silicon oxide to aluminum oxide, sodium oxide to silicon oxide, calcium oxide to silicon oxide and sodium oxide to aluminum oxide were evaluated from the XRF results of the precursors/source materials and the chemical composition of the reagents. These chemical ratios are found to fall within the range of AAMs with adequate workability and strength characteristics as per recent studies on fly ash and slag-based mortars [1].  
Figure 1: Grain size distribution of SCMs, cement and silica sand.
###### Abstract  
This paper proposes an improvement of the conventional Lightweight Steel Frame (LSF) wall structure suitable for the design of high-performance modular buildings. A mobile module, named MUZA, is used as a case study building to analyse the performance of such LSF structures in terms of their thermal bridging effect on the _U_-value of the opaque envelope elements, linear heat losses at junctions, and moisture condensation risk, as well as thermal bridging effect on the overall energy performance of the building. The study included an additional climate- and orientation-dependent analysis that examined the performance of MUZA under various conditions. The main conclusion is that the steel studs increase the _U_-value from 28.4% to 41.6% compared to cases without the studs, which consequently increases transmission losses through opaque elements. Thanks to the continuous covering of the metal studs with thermal insulation, the thermal bridges at the element junctions are minimized, and in almost all cases, the \(\Psi\)-values are well below 0.1 W/(m-K) and are free from moisture condensation. The overall impact of thermal bridges on heating energy demand is significant, while the impact on cooling energy is less pronounced. The designed module with the proposed LSF wall structure can meet the Croatian requirements for Nearly Zero-Energy Buildings (NZEB), but the shading devices and photovoltaics orientation must be optimized depending on the climatic conditions and the orientation of the large transparent openings. MUZA can be a promising solution for post-disaster housing, providing better indoor environmental quality, healthy living conditions, and low energy bills for the affected people. In addition, it can also be used for permanent housing when a fast and robust modular construction is required which is also energy efficient and sustainable.  
Keywords:modular construction; lightweight steel frame building; Nearly Zero-Energy Building; thermal bridge; energy performance; numerical simulations; thermal transmittance +
Footnote †: journal: Applied Sciences
###### Abstract  
In recent times, the field of wireless sensor networks (WSNs) has attained a growing popularity in observing the environment due to its dynamic factors. Sensor data are gathered and forwarded to the base station (BS) through a wireless transmission medium. The data from the BS is further distributed to end-users using the Internet for their post analysis and operations. However, all sensors except the BS have limited constraints in terms of memory, energy and computational resources that degrade the network performance concerning the network lifetime and trustworthy routing. Therefore, improving energy efficiency with reliable and secure transmissions is a valuable debate among researchers for critical applications based on low-powered sensor nodes. In addition, security plays a significant cause to achieve responsible communications among sensors due to their unfixed and variable infrastructures. Keeping in view the above-mentioned issues, this paper presents an energy-aware graph clustering and intelligent routing (EGCIR) using a supervised system for WSNs to balance the energy consumption and load distribution. Moreover, a secure and efficient key distribution in a hierarchy-based mechanism is adopted by the proposed solution to improve the network efficacy in terms of routes and links integrity. The experimental results demonstrated that the EGCIR protocol enhances the network throughput by an average of 14%, packet drop ratio by an average of 50%, energy consumption by an average of 13%, data latency by an average of 30.2% and data breaches by an average of 37.5% than other state-of-the-art protocols.  
energy efficiency; graph clustering; key distribution; link security; wireless sensor networks +
Footnote †: journal: Accepted: 4 August 2020; Published: 6 August 2020
# Characterization of the Migration of Soil Particles in Lateritic Soils under the Effect of Rainfall
## 3 Experimental Phenomena  
In this experiment, we conducted experiments for different rainfall intensities and found some characteristic phenomena exhibited by slopes when subjected to rainfall erosion. Although the order of appearance of these characteristic phenomena may vary slightly depending on the rainfall intensity, similar phenomena are presented under each rainfall intensity. The specific phenomena can be categorized into the following three stages:  
* \"Mud mask\" stage  
This stage occurs at the beginning of the rainfall and the appearance and disappearance of the clay film is significantly earlier as the intensity of rainfall increases. Due to the clay particles in laterite and a very small amount of organic matter with viscous, when the rainfall began, the electrostatic force on the surface of the soil fine particles of the slope surface caused by the bonding of the water film will be fine particles linked, the formation of the \"mud film\" shown in Figure 7a. The appearance of the \"mud film\" on the slope surface slows down soil erosion and water flow rate to a certain extent, but as the rainfall continues, the impact of raindrops and the hydrodynamic force is further enhanced, and the fine particles on the slope surface begin to lose. At this time, the slope changes will enter the following second stage:  
* Fine channel erosion stage In this stage, the water flow forms narrow and shallow small gullies on the slope surface, and the fine gullies are first formed at the toe of the slope and gradually develop towards the top of the slope. As shown in Figure 7b,c, with the formation and development of fine gullies, a large amount of fine granular material on the slope surface is carried away, which is also the most serious stage of slope erosion. However, the development of fine watercourses is uncertain due to the random nature of the distribution of large gravels on the slope surface. The presence of large-grained gravel causes the watercourse to curve or widen, causing the watercourse to erode along and around the gravel. Erosion causes the adjacent gravels on the slope surface to collapse at some point, and the tumbling of the gravels and re-erosion of the newly exposed fines cause a sudden increase in the rate of sand transport on the slope. With the loss of fine particles, the gradual exposure of large particles will lead to the following stage:  
* Roughening stage As the rainfall continues, the fine particles are carried away, and the slope gravel (feldspar, quartz, etc.) gradually accumulates to cover the slope surface. As shown in Figure 7d, when the slope surface appears obvious \"coarsening phenomenon\", the slope runoff will become clarified, and after the coarsening of the slope surface, the pore size will be more conducive to rainfall infiltration, resulting in increased erosion within the slope.
# Review on Application of Quaternary Ammonium Salts for Gas Hydrate Inhibition
## 3 Gas Hydrate Inhibition
### Thermodynamic Hydrate Inhibitors (THIs) and Low Dosage Hydrate Inhibitors (LDHIs)  
Conventional THIs are usually based on anti-freezing solvents like methanol and mono ethylene glycol (MEG) [32], which principally works by shifting hydrate liquid vapor equilibrium (HLVE),  
Figure 1: The three common gas hydrate structures with assembling of unit cells. (a) Structure I, (b) Structure II and (c) Structure sH.  
however once the hydrate formation initiates, they facilitated the hydrate nucleation process and demonstrated kinetic promoters characteristics [20; 33]. Meanwhile, LDHIs are generally classified into two types, kinetic hydrate inhibitors (KHIs) and anti-agglomerants (AAs). The inhibition mechanism of LDHIs differs from THIs. The inhibition by KHIs is achieved by delaying the nucleation process of the hydrate formation [34], whereas AAs allow hydrate formation however avoid agglomeration. Typically, KHIs are water-soluble polymers like polyvinyl pyrrolidone (PVP) and polyvinyl caprolactam (PVCap) [35]. Figure 2 shows a schematic diagram of kinetic hydrate inhibition mechanisms via adsorption and perturbation [36]. Adsorption inhibition shows that inhibitor molecules are adsorbed on the hydrate crystals, whereas perturbation inhibition works by disturbing the water molecules' structure. In the past decade, ionic liquids (ILs), amino acids (AACs) and quaternary ammonium salts (QAS) [37] have been introduced as green hydrate inhibitors, as well as dual function inhibitors, because they are environmentally friendly and have shown good inhibitory performance as both THIs and KHIs [38; 39; 40; 41; 42; 43; 44; 45]. ILs are salts that are generally composed of heterocyclic cations and inorganic anions [38]. ILs have been developed as both green chemicals and designer solvents since their structure and physical properties can be fine-tuned for diverse and specific applications [10; 46; 47]. ILs are water-soluble, non-volatile, and less toxic than methanol, and the thermodynamic inhibition performance of some ILs is comparable to that of methanol [19; 20]. Therefore, ILs are good substitutes to methanol as THIs.
# Radio Wave Propagation and WSN Deployment in Complex Utility Tunnel Environments +
## 1 Introduction
Finally, an infrastructure security and a work safety monitoring application prototype is developed in order to warrant work safety legislation. The paper is organized as follows: the 3D-RL deterministic employed technique, as well as the considered real and simulated underground scenario are described in Section 2. Section 3 presents the radio channel analysis and the required convergence analysis due to the particular characteristics of the scenario. This analysis was performed compared with experimental measurements in the real utility tunnel in order to obtain the optimal simulation parameters. Once the optimal parameters were obtained, large- and small-scale simulation results within the tunnel were presented in order to characterize the radio wave propagation within this particular environment. In Section 4, the WSN deployment issues are discussed, and the infrastructure security and work safety monitoring application prototype are presented. Finally, the conclusions are given in Section 5. A schematic view of the structure of this paper is presented in Figure 1.
# Wi-Senser: Contactless Head Movement Detection during Sleep Utilizing WiFi Signals
## 2 Preliminaries
\begin{array}{ll}|H(f_{i},t)|^{2}&=|H_{\rm s}(f_{i})|^{2}+\sum\limits_{k\in P _{d}}|a_{k}(f_{i},t)|^{2}\\ &+\sum\limits_{k\in P_{d}}2|H_{\rm s}(f_{i})||a_{k}(f_{i},t)|\cos\Bigl{(}2\pi \frac{d_{k}(0)+v_{k}t}{\lambda_{i}}+\phi_{\rm s}-\phi_{k}\Bigr{)}\\ &\sum\limits_{\begin{subarray}{c}k\in P_{d}\\ k\
eq l\end{subarray}}2|a_{k}(f_{i},t)||a_{l}(f_{i},t)|\cos\Bigl{(}2\pi\frac{( v_{l}-v_{k})t+d_{l}(0)-d_{k}(0)}{\lambda_{i}}+\phi_{k}\\ &-\phi_{l}\Bigr{)}\end{array}  \tag{7}\]  
where \(\phi_{\rm s}\), \(\phi_{k}\), and \(\phi_{l}\) represent the initial phase under static and dynamic paths, respectively, which can be regarded as constants. In addition, \(2\pi\frac{d_{k}(0)}{\lambda_{i}}\) and \(2\pi\frac{d_{l}(0)}{\lambda_{i}}\) represent the initial phase shifts under different dynamic paths, which can also be regarded as constants. Therefore, we can obtain:  
\[2\pi\frac{d_{l}(0)-d_{k}(0)}{\lambda_{i}}+\phi_{k}-\phi_{l}=\phi_{kl} \tag{8}\]  
\[2\pi\frac{d_{k}(0)}{\lambda_{i}}+\phi_{\rm s}-\phi_{k}=\phi_{sk} \tag{9}\]Substituting Equations (8) and (9) into Equation (7), we can obtain:  
\[ \begin{split}|H(f_{i},t)|^{2}=|H_{s}(f_{i})|^{2}+\sum\limits_{k\in P _{d}}|a_{k}(f_{i},t)|^{2}+\sum\limits_{k\in P_{d}}2|H_{s}(f_{i})||a_{k}(f_{i},t )|\cos\Bigl{(}2\pi\frac{v_{k}t}{\lambda_{i}}+\phi_{sk}\Bigr{)}\\ +\sum\limits_{\begin{subarray}{c}k\in P_{d}\\ k\
eq l\end{subarray}}2|a_{k}(f_{i},t)||a_{l}(f_{i},t)|\cos\Bigl{(}2\pi\frac{ (v_{l}-v_{k})t}{\lambda_{i}}+\phi_{kl}\Bigr{)}\end{split}  \tag{10}\]  
Since \(|H_{s}(f_{i})|^{2}\) and \(\sum\limits_{k\in P_{d}}|a_{k}(f_{i},t)|^{2}\) are approximately constants, the amplitude change in CSI caused by human movement (\(|H(f_{i},t)|\)) can be approximated as a sum of DC components and cosine signals whose frequencies change at a speed of \(v_{k}\) of dynamic paths and amplitudes change with the length \(d_{k}\) of dynamic paths. In summary, human body movement causes changes in dynamic paths in WiFi signal multipath propagation, which in turn leads to changes in the CSI amplitude of the received signal.
# Topology and Response Surface Optimization of a Bicycle Crank Arm with Multiple Load Cases
## 4 Conclusions  
In this paper, topology and response surface optimization methods have been applied to a bicycle crank arm with multiple load conditions. Several scenarios of mass minimization have been investigated resulting in several optimized crank arm designs. The following conclusions are obtained:  
1. The topology optimization successfully provides structural mass reduction up to 70% from the initial mass. This is a very effective way to create a lightweight structure that is important in the development of future bicycle design. From several constraint investigations, the topology  
Figure 24: Normalized Von Mises stress comparison to [PERSON] et al. [32].  
Figure 23: Dynamic test result (double crank arms operation).  
optimization method is also capable of providing many geometrical options for the design of a lightweight crank arm.
2. The response surface method is also found to be effective as a shape optimization tool for this crank arm case. It is able to enhance the stress level performance of the optimized crank arm obtained from topology optimization.
3. The optimized model has been validated by static and dynamic experiments which shows a very well agreement. A comparison study with the previous conventional bike crank arm design shows that the optimized geometry, with less mass, can give a similar performance and possibly be improved in the future.
4. Improvement opportunities can be made in the future involving more detail of dynamic analysis and experimental studies, i.e., speed variations and road conditions to enhance the application of the crank arm in some particular application, i.e., hybrid and electric bicycle.  
In summary, the topology and response surface optimization are the effective combination tools for the bicycle crank arm design optimization.  
Conceptualization, A.Y.I. and B.K.; methodology, A.Y.I. and B.K.; software, B.K.; validation, A.Y.I. and B.K.; formal analysis, A.Y.I. and B.K.; investigation, A.Y.I., G.N., and B.K.; resources, A.Y.I. and B.K.; data curation, A.Y.I. and G.N.; experiment, A.Y.I. and N.T.; writing--original draft preparation, A.Y.I.; writing--review and editing, B.K.; visualization, A.Y.I. and B.K.; supervision, B.K.; project administration, B.K.; funding acquisition, B.K. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Research Foundation of Korea (NRF) grant by the Korea government (no. NRF-2018R1D1A1B07050370) and the Human Resources Development Program (grant no. 20194010201800) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grants by the Korea government.  
The authors declare no conflict of interest.
# Structural Evaluation of Cable Bolts under Static Loading
## 2 Literature Review
### Rock Bursts  
The first rock burst was recorded in South Africa at the Witwatersrand Gold Mines in the early 1900s, where sudden failure of rock masses occurred. Since this incident, there has been a clear link between mining activities, particularly at greater depths, and rock burst incidents, where it has been established that rock bursts are highly associated with hard rocks and geological faults [16].  
Initially, [PERSON] and [PERSON] (1994) [17] proposed a classification of differing rock burst types, categorising them into five main types, which were strain bursting, buckling, face crushing (now known as fault slips), shear ruptures and fault slips. However, these rock burst types have more recently been refined into three distinct categories by [PERSON] and [PERSON] (2012) [9], which are strain bursts, where high stress concentrations at the edge of excavations exceed rock strength; pillar bursts, where support pillars fail violently due to large volume of rock failure; and fault slip bursts, where failure occurs due to slippage between existing faults and newly generated shear ruptures within the rock mass.  
To manage and create ground support systems capable of mitigating rock burst damage, it is necessary to understand the damage mechanisms of rock bursts. Rock burst damage mechanisms and their causes have been classified into three types by [PERSON] et al. (1996): rock bulking, where rock mass with high stress but low stored stress energy fractures; rock ejection, where rock with excess stored energy ruptures or remote seismic events transfer dynamic stress creating a strain burst; and seismically induced rock fall, where rock strength is inadequate to resist forces that are accelerated due to seismic waves [9].  
Therefore, to design a support system that adequately negates the damage mechanisms of rock bursts, [PERSON] et al. (1996) devised three necessary support functions that must operate concurrently: reinforce the rock mass to strengthen it, such that it can support itself and control bulking [18]; retain broken rock mass to prevent unravelling and further failure by using surface supports; and holding rock, reinforcement and surface elements securely to allow for the dissipation of dynamic energy [16]. These three support functions have been further built upon, and [PERSON] and [PERSON] (2009) [15] advise that an effective rock support system must also account for dynamic energy absorption capacity, large displacement capacity and large load carrying capacity simultaneously, and thus created seven rock burst design principles. As burst-prone excavations cannot always be avoided, especially as mining depth increases, the next best thing is utilising effective and capable ground support systems.