esa-sceva/satcom-chunk-collection huggingface dataset:
## 3 Electromagnetic Model and Current Decoupling  
### Electromagnetic Model Analysis  
#### 3.1.1 Parameter and Coordinate Definition  
Figure 2 shows the model of the concentric winding in the Halbach magnetic field. This can be seen from Figure 2 that one set of concentric windings consists of the outer and inner coils. They are connected in series, but the currents circulating in them are in opposite directions. To simplify the calculation, each of them is simplified into four different cuboids. \(\tau_{n}\) is the pole pitch; \(l_{w}\) is the equivalent linear length of the outer coil; \(l_{n}\) is the equivalent linear length of the inner coil; \(w_{c}\) is the coil width; \(h_{c}\) is the coil height; and \(c_{t}\) and \(c_{b}\) are the height coordinate positions of the coil.  
Figure 1: The maglev planar motor structure.  
Figure 2: Top views and A-A view of the components of a maglev planar motor: a Halbach array and a concentric structure winding.  
\[\mathbf{K}(\boldsymbol{p})=\left[\begin{array}{cccc}F_{x1}(\boldsymbol{p})&F_{x2} (\boldsymbol{p})&\cdots&F_{x16}(\boldsymbol{p})\\ F_{y1}(\boldsymbol{p})&F_{y2}(\boldsymbol{p})&\cdots&F_{y16}(\boldsymbol{p}) \\ F_{z1}(\boldsymbol{p})&F_{z3}(\boldsymbol{p})&\cdots&F_{z16}(\boldsymbol{p}) \\ T_{x1}(\boldsymbol{p})&T_{x2}(\boldsymbol{p})&\cdots&T_{x16}(\boldsymbol{p}) \\ T_{y1}(\boldsymbol{p})&T_{y2}(\boldsymbol{p})&\cdots&T_{y16}(\boldsymbol{p}) \\ T_{z1}(\boldsymbol{p})&T_{z2}(\boldsymbol{p})&\cdots&T_{z16}(\boldsymbol{p}) \end{array}\right] \tag{27}\]  
where \(\boldsymbol{p}\) is the position vector and \(\boldsymbol{K}(\boldsymbol{p})\) is a coefficient matrix about the electromagnetic force and torque relevant to the position.  
It can be seen from Equation (25) that the forces and the torques can be calculated when the current in the winding is known. In practical control, however, the current in each winding needs to be derived based on the expected forces and torques. The currents can be derived through the generalized inverse matrix method. In general, more than one answer can be obtained in the above process. To get only one answer for the practical control, we still need to add extra constraints. The heat loss has a significant impact on the performance of the control system and, therefore, we choose the answer that can generate the least heat loss. This extra constraint is expressed as:  
\[\boldsymbol{i}=\underset{i}{\text{argmin}}\|\boldsymbol{i}\|_{2} \tag{28}\]  
The Moore-Penrose generalized inverse matrix of \(\boldsymbol{K}(\boldsymbol{p})\) is shown as:  
\[\boldsymbol{K}^{-}(\boldsymbol{p})=\boldsymbol{K}(\boldsymbol{p})^{\text{T}} \Big{(}\boldsymbol{K}(\boldsymbol{p})\boldsymbol{K}(\boldsymbol{p})^{\text{T }}\Big{)}^{-1} \tag{29}\]  
Thus, we can derive the current in each winding as:  
\[\boldsymbol{i}=\boldsymbol{K}^{-}(\boldsymbol{p})\boldsymbol{W} \tag{30}\]  
From Equation (30) the needed current in each winding to obtain the desired forces and torques can be derived, and the derived current is the input of the maglev planar motor.
# A Wideband Circularly Polarized Filtering Dipole Antenna
## 2 Antenna Design  
### Antenna Configuration  
Figure 1 illustrates the proposed wideband CP filtering crossed-dipole antenna. The structure comprises two dielectric substrates, including a reflector layer and a dipole antenna radiating layer. Both substrates employ [PERSON] (Chandler, AZ, USA) RO4003 (\(\tan\delta=0.0027\), \(\epsilon_{r}=3.55\)). Figure 1b,c depict the upper and lower surfaces of the dipole antenna layer, respectively. It can be observed that both the upper and lower surfaces of the dipole antenna layer are printed with one arm of the cross dipoles aligned along the x- and y-directions, which are interconnected through a quarter-wavelength delay line. The coaxial inner conductor is connected to the x-oriented printed on the upper surface dipole arm. Furthermore, the y-oriented printed on the upper surface dipole arm is excited at the same through the quarter-wavelength delay line. The x-oriented and the y-oriented printed on the lower surface dipole arms are then connected to the coaxial outer conductor. Therefore, the dipole along the x-direction has a 90\({}^{\circ}\) phase lead over the dipole along the y-direction, achieving left-handed circular polarization (LHCP) performance. As illustrated in Figure 1b,c, to realize the filtering performance, the ends of the four dipole arms are vertically extended. This configuration induces loop currents between adjacent dipoles, generating a radiation null in the upper band. To broaden the axial ratio bandwidth, four parasitic patches are introduced parallel to the dipole arm ends. These patches not only create an additional radiation null in the upper band, but also enhance frequency selectivity at band edges while extending the axial ratio bandwidth. Furthermore, Figure 1d shows a square-ring slot etched in the ground plane to introduce a radiation null in the lower band. The optimized parameters are presented in Figure 1. This structure ultimately  
realizes a wideband circularly polarized (CP) antenna with integrated filtering radiation performance. Based on this structure, a wideband CP antenna with filtering radiation performance is realized.  
Figure 1: Antenna structure. (**a**) Total view. (**b**) Dipole antenna layer top side. (**c**) Dipole antenna layer bottom side. (**d**) Ground plane (\(G_{1}=90;G_{2}=70;G_{3}=66;h=30;t_{1}=0.813;w_{1}=5;w_{2}=13;w_{3}=1.2;w_{4}=7.4;w_{5}=3; w_{6}=7;g_{1}=0.5;g_{2}=0.9;g_{3}=2;l_{1}=70;l_{2}=26;l_{3}=24;l_{4}=13;l_{5}=7; l_{6}=4.2;\ R_{1}=4,\)all in mm).
# A Heuristics-Guided Simplified Discrete Harmony Search Algorithm for Solving 0-1 Knapsack Problem
## 3 Simplified Discrete Harmony Search Algorithm for the 0-1 KP  
The HS algorithm is a simple, effective, and flexible metaheuristic for both continuous and discrete optimization problems. Among the three components of the HS algorithm, the memory consideration operator, which learns from historical experience stored in the harmony memory, is the core component. The other two components, the pitch adjustment operator and the random search operator, are designed to enhance its intensification ability and enlarge its diversification, respectively.  
The cooperation of these two components can obtain good balance between exploration and exploitation for the HS algorithm. Although the basic HS algorithm is both simple and easy to implement, to design an HS algorithm with excellent performance for a specific problem is far from a simple task.  
Based on the characteristics of the problem at hand, we must analyze the three components of the basic HS algorithm carefully to answer the following two questions: (1) whether a component is needed for the problem at hand, and (2) how to implement this component if it is needed. The 0-1 KP has the following two characteristics. One is that each variable has only two possible values, i.e., 0 or 1. The other is that an item with a high profit-weight ratio or profit should be picked with high priority. Based on these two key characteristics of the 0-1 knapsack problem (0-1 KP), the necessity and implementation details of the memory consideration operator, pitch adjustment operator, and random search operator are explored in the following subsections.
## 3 Results  
### Static GNSS Measurements  
Static measurements were made at 36 points spaced about 20 km apart. Figure 5 shows the mean annual elevation change at these points.  
The catchment areas of the two glaciers Helheim (East coast in Figure 5) and Ilulissat Isbrae (West coast in Figure 5) are clearly visible. The watershed is located at km 420 (in Figure 5) and represents the highest point along the route. The 2002, 2006, 2010, and 2015 measurements seem to indicate an acceleration of mass loss, but the 2020/21 measurement does not confirm this. It appears that longer time series are needed to identify more reliable trends.  
Figure 6 shows the absolute elevation changes at the camps between 2002 and 2021. While there is hardly any increase in the accumulation area (max. 2.1 m), there is an elevation loss of max. 38.7 m in the reservoirs in the Ilulissat Isbrae catchment. An elevation decreases of max. 6.4 m in the comparable area in the Helheim Glacier catchment and 10.1 m in the marginal area of the ice sheet on the east coast can be seen in Figure 6.
## 5 Limitations  
The results presented in this work are affected by limitations that can be summarized as follows. The models and simulation results did not consider the interaction between blood flow and arterial walls, the real stent mechanical behavior and the arterial compliance. The rigid walls approximation could of course influence flow patterns and hence the WSS related indices. Furthermore, no information about the stent structural behavior and arterial stresses and strains can be given. However, in the literature it is stated that the vessel motion in cerebral aneurysm hemodynamics is limited [39].  
Additionally, in the literature, the necessity of using FSI in stented artery is still debated as its influence on the WSS related variables is limited [47].  
Additionally, the results are not validated with an appropriate experimental study or with a clinical follow up study. Finally, it has to be observed that the present study offers the possibility of more extended patient-specific analyses in which the real effect of the stent placement on the geometry of the cerebral artery can be more accurately studied. The latter include the straightening promoted by the FDS depending on its rigidity/porosity, etc. [24; 33].  
Lastly, there are common locations of the aneurysm which are very different from that considered, such as the cavernous portion of internal carotid artery and/or portions of the vertebral artery. In the former, the parental artery is more curved compared to that considered in the present study. In the latter, the aneurysm sacs have a lower dome/neck ratio, rather than a spherical shape. These aspects reinforce the necessity of patient-specific studies, as discussed in the literature [10; 48].
# Sulfonic Resins as Catalysts for the Oxidation of Alcohols with H\({}_{2}\)O\({}_{2}\)/KBr
## 2 Results and Discussion
Under these conditions, and after nine runs, the cumulative productivity is around 20 mol of methyl 9(10)-oxostearate (**2a** + **2b**) per mol of sulfonic group; meanwhile, in the homogeneous phase, the productivity is only five. The method was then applied to the oxidation of other alcohols (Scheme 4), including fatty primary alcohols (**3**) and cyclic secondary alcohols (**6** and **8**). The most relevant results are shown in Table 4. The primary alcohols (**3**) were oxidized to the corresponding carboxylic acids (**4**), whereas the aldehydes were not detected, in agreement with the related oxidation methods [30]. The increase in the chain length of the fatty alcohols makes the reaction slower, as shown by the less efficient oxidation of 1-octadecanol (**3b**) in comparison with 1-dodecanol (**3a**). The presence of an acidic catalyst favors the reaction of the formed carboxylic acid with the unconverted alcohol, leading to esters (**5**) being produced as the main products and the possibility of the total conversion of the fatty alcohols being prevented, even after increasing the amount of oxidant or KBr. In the case of secondary cyclic alcohols, they are more easily oxidized to ketones but the effectiveness of the method depends on the steric hindrance around the hydroxyl. 2-Methylcyclohexanol (**6**) was tested as a 1:1 mixture of _trans_ and _cis_. The residual unconverted alcohol was always the _trans_ isomer, showing that it was less reactive to oxidation. This effect explains the lower reactivity of (\(-\))-menthol (**8**), which possesses a bulkier isopropyl group in the _trans_ relative position to the hydroxyl. The corresponding cyclohexanes, 2-methylcyclohexanone (**7**) and (\(-\))-menthone (**9**), were obtained with high selectivity, namely 87%; however, some by-products were detected in low amounts. It was not possible to identify them, although the presence of Br in the molecules was confirmed by GC-MS, a result that again confirms the role of bromine species in the oxidation process. Figure 1: Recovery of Dowex 50W\(\times\)8 in the oxidation of methyl 9(10)-hydroxystearate (**1a** + **1b**) with H\({}_{2}\)O\({}_{2}\)/KBr. Reaction conditions: 0.5 mmol of methyl 9(10)-hydroxystearate, 0.1 mmol of KBr, 0.75 mmol of 60% H\({}_{2}\)O\({}_{2}\), 0.2 mmol of sulfonic groups, 1 mL of CH\({}_{2}\)Cl\({}_{2}\)/H\({}_{2}\)O (9:1 \(v\)/\(v\)), rt, 24 h. Blue bars indicate the result after the reactivation of the resin with HCl.
Therefore, the drug development research studies for [PERSON]'s disease are focused on controlled and targeted levodopa release to provide reduced dosage frequency and prolonged therapeutic effect. Controlled drug delivery systems offer some advantages, such as reduced side effects, reduced toxicity, reduced dosage frequency, improved patient compliance, and prolonged pharmacological effects in comparison to conventional methods [6; 7]. In the present study, levodopa-loaded scaffolds, based on poly (lactic) acid (PLA) and chitosan (CS), were produced using 3D-printing technology as a drug delivery patch. PLA is a biodegradable synthetic material that is suitable for many tissue engineering applications. This polymer is frequently preferred in studies for 3D-printing technology, due to its properties of biocompatibility, high mechanical strength, low cost, and compatibility with drug delivery systems [8; 9]. It was found that PLA-based scaffolds can induce the desired release kinetics of the active substances by eliminating the initial burst [10; 11]. CS, a natural biopolymer, provides the scaffolds with improved biological properties and assists the efficient adhesion and growth of cells, due to its high biocompatibility in the case of using it to form a scaffold. It is a preferred biomaterial for many tissue engineering applications, thanks to its unique properties, such as being biodegradable, flexible, antimicrobial, non-toxic, and easy to use [12; 13]. The increased absorption and prolonged release properties of the drugs are due to the mucoadhesive surface properties of CS [14]. Moreover, CS has a higher affinity for biological membranes and is a good candidate for drug delivery systems [11]. These scaffolds used for tissue engineering applications may be commonly used to mimic the microenvironment required for the improvement of the performance of the cells [15]. The 3D printing method has a high potential to produce scaffolds with the mentioned properties. It is possible to create structures that have complex geometry for mimicking the microenvironment by 3D printing, compared to mold casting and other traditional tissue engineering techniques. 3D-printing allows the modification of scaffolds' characteristics such as thickness and pore size [16]. In this study, novel levodopa-loaded 3D-printed PLA/CS scaffolds were produced for [PERSON]'s disease, and these scaffolds were found to possibly be a promising alternative drug delivery system for drug administration routes, such as intranasal or transdermal.
# IoT Privacy and Security Challenges for Smart Home Environments
## 6 A Suitable Smart Home Architecture for Security
### Cloud Architectures and Security  
Collaboration between devices is an important aspect of IoT. Such interoperable functions require high processing power which most IoT devices are not capable of. To solve the performance problem of IoT devices, researchers have proposed cloud-based solutions for IoT. The cloud has the resources to monitor, collect, store and process data from IoT devices. By analyzing this data, the cloud can trigger actions according to user-defined policies to achieve complex Smart Home control. The cloud-based architecture of IoT is also known as the Cloud of Things (CoT).  
The authors in [32] propose an IoT cloud architecture based on the IETF's CoAP protocol [22]. The architecture consists of three decoupled stages which are the network, protocol and business logic stages. Each stage includes an incoming event queue, a thread pool and an event handler that processes the stage logic. The lightweight DTLS [29] is used by this architecture as its security protocol for authentication and communication.  
A secure scheme for the Home Area Network (HAN) based on cloud computing has been introduced in [33]. A Home Management System (HMS) manages devices and policies, and provides the access point for users. In the paper, the authors implement the HMS functions in the cloud and the HMS interfaces with the cloud services. This scheme employs symmetric key encryption to apply confidentiality between end-to-end communications and each smart object is assigned a unique key.  
The cloud-based solution removes the need for a separate home controller and provides a good way for IoT to connect and cooperate; however, it replaces the need for local computation with a need for substantial Internet communication. Due to the resource-limited nature of IoT, large amounts of raw data generated by IoT devices have to be transferred to the cloud without pre-processing; therefore, devices in the home need a high-speed, low-latency, always-on Internet connection, but such always-on high-speed Internet connections are not always available, especially in rural or remote areas. Control latency is increased, especially if the servers are overseas or the network is congested.  
All devices must be accessible via the Internet which presents a broad attack surface, and each device needs to have sufficient resources to implement full network security protocols. Denial of service attacks, based on limiting access to the broader Internet, or occasional network outages may cause mission-critical tasks such as home healthcare and physical security systems to fail. Furthermore, because users do not have the full control of their cloud services, they have to trust cloud providers to implement appropriate and sufficient security measures for their data, but it is not always the case.  
Because cloud-based systems fail without always-on network connectivity, we do not believe that they can provide a secure and available Smart Home system by themselves, and they also expose all network devices to network attacks.
applied sciences Article  
Efficient Realization for Third-Order Volterra Filter Based on Singular Value Decomposition  
[PERSON], [PERSON], [PERSON]  
1 Faculty of Engineering Science, Kansai University, Osaka 564-8680, Japan College of Information Science and Engineering, Ritsumeikan University, Kusatsu 525-8577, Japan Correspondence: [EMAIL_ADDRESS] These authors contributed equally to this work.  
Nonlinear distortion in loudspeaker systems degrades sound quality and must be properly compensated for by linearization techniques. One technique to reduce nonlinear distortion is to use a Volterra Filter, which approximates the nonlinearity of the target loudspeaker using the Volterra series expansion. In general, the Volterra Filter is computationally very expensive, and the amount of computation needs to be reduced for real-time processing. In this paper, we propose an efficient implementation of the third-order Volterra filter based on singular value decomposition[PERSON] The proposed method determines the necessary coefficients based on the symmetry of the third-order Volterra filter and applies singular value decomposition to them[PERSON] In the filter structure consisting of singular values and their corresponding singular vector, the computational complexity of the third-order Volterra filter can be reduced by eliminating the part of the filter with small singular values. By focusing on the magnitude of the singular values, the proposed method can improve the computational efficiency of the third-order Volterra filter without decreasing its approximation accuracy. Simulation results show that the proposed method can improve the computational efficiency by 60% while maintaining the nonlinear distortion compensation performance of the micro-speaker for smartphones by about 8 dB.  
nonlinear signal processing; volterra filter; compensation of nonlinear distortions; singular value decomposition; micro-speaker
## 4 Experiments
### The Performance of Similar User Recommendation  
To evaluate the performance of user recommendation and to deal with posts in different languages, we further collected a larger dataset (denoted as Dataset_2) where 12 tags were randomly selected from the list of top 100 hashtags on Instagram in 2018 as queries. There were 1143 users and 49,353 posts in Dataset_2, where the major language was Chinese.  
In order to compare the performance of different models in similar user recommendation, we established the ground truth for similar users as follows: in the absence of real user preferences, we assumed that the hashtags in each user's posts represents the user's implicit preference and attributes. Thus, the set of hashtags \(\textit{Tags}(u_{i})\) for each user \(u_{i}\) was collected from all the posts as the real preference. The similarity between users was calculated by Jaccard similarity as follows:  
\[\text{sim}\big{(}u_{i},u_{j}\big{)}=\text{Jaccard}\big{(}\text{Tags}(u_{i}), \ \text{Tags}(u_{j})\big{)}. \tag{6}\]  
Then, the ground truth of top \(k\) similar users for a given user \(u_{i}\) was defined as follows:  
\[SL_{k}(u_{i})=\big{\{}u_{j}|argmax\_k_{j}\,sim\big{(}u_{i},u_{j})\big{\}}, \tag{7}\]  
where \(j\
eq i\). That is, top \(k\) users with the highest similarity to the given user were regarded as the ground truth.  
With the recommendation ground truth, we then defined the evaluation metric of the top-\(k\) accuracy of a user \(u_{i}\) by calculating the Jaccard similarity between the recommendation list \(RL_{k}(u_{i})\) generated by the proposed method and the ground truth \(SL_{k}(u_{i})\), as follows:  
\[\text{Accuracy}_{k}(u_{i})=\frac{RL_{k}(u_{i})\cap\ SL_{k}(u_{i})}{RL_{k}(u_ {i})\cup\ SL_{k}(u_{i})}. \tag{8}\]  
Then, the overall performance of the model was calculated by the average of the top-\(k\) accuracies for all users. To compare the performance of different models, we evaluated the average top-\(k\) accuracies for each model when recommending top \(k\) similar users, for different values of \(k\).
# Fault Diagnosis Method of Rolling Bearing Based on CBAM_ResNet and ACON Activation Function
## 2 Materials and Methods
### Proposed Methodology  
Fault diagnosis is actually inseparable from the classification task. CNN has obvious advantages in classification tasks and key feature extraction. However, on the one hand, traditional CNN extracts deeper features by deepening the number of network layers. Unfortunately, when the number of layers is too large, the network model faces the problem of gradient dispersion or explosion and network degradation [35], which will lead to a decrease in the accuracy of fault diagnosis models.  
On the other hand, in actual industrial production, the vibration signal is highly susceptible to interference from environmental noise, and the transforming load work increases the complexity of the collected data, thus, weakening the ability of the model to extract key features. To cope with these problems, this paper constructs a CNN with residual connections while combining the CBAM attention mechanism and ACON activation function, and proposes a rolling bearing fault diagnosis model based on CBAM_ResNet and ACON activation function.  
Figure 3: Structure of the CBAM.