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EISSN : 2073-8994
Current Publisher: MDPI AG (10.3390)
Total articles ≅ 5,886
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Published: 17 April 2021
Symmetry, Volume 13; doi:10.3390/sym13040703

Abstract:
Owing to the increased use of urban rail transit, the flow of passengers on metro platforms tends to increase sharply during peak periods. Monitoring passenger flow in such areas is important for security-related reasons. In this paper, in order to solve the problem of metro platform passenger flow detection, we propose a CNN (convolutional neural network)-based network called the MP (metro platform)-CNN to accurately count people on metro platforms. The proposed method is composed of three major components: a group of convolutional neural networks is used on the front end to extract image features, a multiscale feature extraction module is used to enhance multiscale features, and transposed convolution is used for upsampling to generate a high-quality density map. Currently, existing crowd-counting datasets do not adequately cover all of the challenging situations considered in this study. Therefore, we collected images from surveillance videos of a metro platform to form a dataset containing 627 images, with 9243 annotated heads. The results of the extensive experiments showed that our method performed well on the self-built dataset and the estimation error was minimum. Moreover, the proposed method could compete with other methods on four standard crowd-counting datasets.
Published: 16 April 2021
Symmetry, Volume 13; doi:10.3390/sym13040699

Abstract:
The collision effects on the low-frequency ion-acoustic Trivelpiece–Gould wave are investigated in weakly and completely ionized plasma waveguides by using the normal mode analysis. In weakly ionized plasma waveguides, it is found that the dependence of the harmonic mode on the absolute value of the scaled damping rate shows the opposite tendency for large and small radii of the cylindrical waveguide. It is also is found that the scaled damping rates for both weakly and completely ionized plasma waveguides decrease with an increase of the electron temperature. It is interesting to note that the scaled damping rate for weakly ionized plasma waveguides shows anti-symmetric behavior when the Trivelpiece–Gould wave propagates in the negative-z direction. However, it is found that the scaled damping rate for completely ionized plasma waveguides shows the symmetric behavior when the Trivelpiece–Gould wave propagates in the negative-z direction.
Published: 16 April 2021
Symmetry, Volume 13; doi:10.3390/sym13040696

Abstract:
Cataract is a disease opacifying the crystalline, leading to a blurred vision and ultimately to blindness. With an aging population, the incidence of cataract is increasing, as well as the number of treatments. The solution available is its complete removal, followed by an implant of an intraocular lens (IOL). Although the post-operative complications on cataract surgeries have been decreasing in general, the bag-IOL complex dislocation is still an issue, probably being the most serious complication under this procedure. In this work, an axisymmetric Finite Element (FE) modelling strategy of the crystalline complex during the process of accommodation under cataract surgery is proposed. The goal was to understand the influence of biomechanical alterations promoted by the IOL on bag-IOL dislocation after surgery. An increase of force and stress in the zonules was verified in the pseudophakic eye compared to the complete eye, which could explain why zonules break years after surgery, leading to the bag-IOL dislocation. The axisymmetric FE model proposed in this work is innovative in this field, which still lacks detailed research, and can be an important complement for the clinical and biomechanical work on the crystalline complex.
Published: 16 April 2021
Symmetry, Volume 13; doi:10.3390/sym13040695

Abstract:
The alignment of visceral and brain asymmetry observed in some vertebrate species raises the question of whether this association also exists in humans. While the visceral and brain systems may have developed asymmetry for different reasons, basic visceral left–right differentiation mechanisms could have been duplicated to establish brain asymmetry. We describe the main phenotypical anomalies and the general mechanism of left–right differentiation of vertebrate visceral and brain laterality. Next, we systematically review the available human studies that explored the prevalence of atypical behavioral and brain asymmetry in visceral situs anomalies, which almost exclusively involved participants with the mirrored visceral organization (situs inversus). The data show no direct link between human visceral and brain functional laterality as most participants with situs inversus show the typical population bias for handedness and brain functional asymmetry, although an increased prevalence of functional crowding may be present. At the same time, several independent studies present evidence for a possible relation between situs inversus and the gross morphological asymmetry of the brain torque with potential differences between subtypes of situs inversus with ciliary and non-ciliary etiologies.
Published: 16 April 2021
Symmetry, Volume 13; doi:10.3390/sym13040701

Abstract:
A scheme for the generalized Chaplygin gas equation of state is shown by using the holographic Ricci dark energy. Regression analysis and a chi-square test were performed. A second order polynomial regression has been established as the relation between the Hubble Parameter and redshift. It has established a set of parameters that can predict the Equation of State (EoS) parameter.
Published: 16 April 2021
Symmetry, Volume 13; doi:10.3390/sym13040697

Abstract:
A lack of memory can lead to job failures or increase processing times for garbage collection. However, if too much memory is provided, the processing time is only marginally reduced, and most of the memory is wasted. Many big data processing tasks are executed in cloud environments. When renting virtual resources in a cloud environment, it is necessary to pay the cost according to the specifications of resources (i.e., the number of virtual cores and the size of memory), as well as rental time. In this paper, given the type of workload and volume of the input data, we analyze the memory usage pattern and derive the efficient memory size of data-parallel workloads in Apache Spark. Then, we propose a machine-learning-based prediction model that determines the efficient memory for a given workload and data. To determine the validity of the proposed model, we applied it to data-parallel workloads which include a deep learning model. The predicted memory values were in close agreement with the actual amount of required memory. Additionally, the whole building time for the proposed model requires a maximum of 44% of the total execution time of a data-parallel workload. The proposed model can improve memory efficiency up to 1.89 times compared with the vanilla Spark setting.
Published: 16 April 2021
Symmetry, Volume 13; doi:10.3390/sym13040694

Abstract:
Purpose: Plyometric exercises, in the form of jumping, are extreme physical activities. The aim of the study was to determine how symmetrical-single versus asymmetrical-continued plyometric exercises differ between men and women and affect speed abilities. Methods: Twenty-two healthy females and forty-four males from different sports practices participated in the investigation. The countermovement jump (CMJ) and drop jump (DJ) of 40/60 cm box were performed on two independent and synchronized force platforms (Bilateral Tensiometric Platform S2P, Ljubljana, Slovenia). The measurement of a standing long jump (SLJ) and all continuous jumps: standing five jumps (SFJ), standing bounce triple jump (SBTJ), five double-leg jumps (FD-LJ), and a 10 m horizontal single leg jump (HSLJ-10mL/R) were performed using OptoJump–Next Microgate (OptoJump, Bolzano, Italy). Results: Statistically significant differences were noted in all jump kinematic and somatic parameters, in favor of the men. The correlations between values of height of symmetrical jumps (bilateral) and distance (SLJ) were stronger in women despite the shorter jumps than the men. When an alpha-level of 0.01 was set, this study demonstrated a stronger correlation between symmetrical-single and asymmetrical-continuous plyometrics exercises and sprints, both men and women. This relationship is due to their similar kinematic and dynamic structures with sprinting steps. Conclusions: The results showed a large dispersion of the relationship (p < 0.05) between jumps and sprints divided into 10, 20 and 30 m, both in men and women. Both types of exercises implemented as a plyometric training regime are an extremely important tool for sprint speed development.
Published: 16 April 2021
Symmetry, Volume 13; doi:10.3390/sym13040700

Abstract:
This paper presents a novel parallel quasi-cyclic low-density parity-check (QC-LDPC) encoding algorithm with low complexity, which is compatible with the 5th generation (5G) new radio (NR). Basing on the algorithm, we propose a high area-efficient parallel encoder with compatible architecture. The proposed encoder has the advantages of parallel encoding and pipelined operations. Furthermore, it is designed as a configurable encoding structure, which is fully compatible with different base graphs of 5G LDPC. Thus, the encoder architecture has flexible adaptability for various 5G LDPC codes. The proposed encoder was synthesized in a 65 nm CMOS technology. According to the encoder architecture, we implemented nine encoders for distributed lifting sizes of two base graphs. The eperimental results show that the encoder has high performance and significant area-efficiency, which is better than related prior art. This work includes a whole set of encoding algorithm and the compatible encoders, which are fully compatible with different base graphs of 5G LDPC codes. Therefore, it has more flexible adaptability for various 5G application scenarios.
Published: 16 April 2021
Symmetry, Volume 13; doi:10.3390/sym13040702

Abstract:
The frame-compatible packing for 3D contents is the feasible approach to archive the compatibility with the existing monocular broadcasting system. To perceive better 3D quality, the packed 3D frames are expanded to the full size at the decoder. In this paper, an interpolation technique enhancing and comparing the quality of enlarged halt vertical left and right stereo video in the top–bottom frame-compatible packing is presented. To this end, the appropriate interpolation modes from fourteen available modes for each row segment, which exploit the correlation between left and right stereoscopic as well as current and adjacent frames of individual view, are estimated at the encoder. Based on the information received from the encoder, at the decoder, the interpolation scheme can select the most appropriate available original data to find the missing values of to-be-discarded row segments. The proposed method outperformed than the state-of-the-art interpolation methods in terms of subjective visualization and numerical PSNRs and SSMI about 11%, with an execution time of about 12% comparisons.
Published: 16 April 2021
Symmetry, Volume 13; doi:10.3390/sym13040698

Abstract:
In a smart city, there are different types of entities, such as nature persons, IoT devices, and service providers, which have different computational limitations and storage limitations. Unfortunately, all of the existing authentication and key exchange (AKE) protocols are designed for either client–server or client–client authentication, including the ones designed for smart cities. In this paper, we present the idea of a compatible authentication and key exchange (CAKE) protocol which provides cross-species authentication. We propose the first CAKE protocol for a smart city that any two valid entities can authenticate with each other and create a secure session key without the help of any third party, while there is also no password table and no public key issuing problem. The entity can be a natural person having biometrics, an IoT device embedded with a physical unclonable function (PUF), or a service provider. Moreover, we extend the CAKE protocol to an anonymous CAKE (ACAKE) protocol, which provides natural persons an anonymous option to protect their privacy. In addition, both the proposed CAKE and ACAKE protocols can deal with the entity revocation problem. We define the framework and the security model of CAKE and ACAKE protocols. Under the security model, we formally prove that the proposed protocols are secure under the elliptic curve computational Diffie–Hellman (ECCDH) problem, the decisional bilinear Diffie–Hellman (DBDH) problem, and hash function assumptions. Comparisons with the related protocols are conducted to demonstrate the benefits of our protocols. Performance analysis is conducted and the experience results show that the proposed protocols are practical in a smart city.
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