Symmetry

277 KiB

Open AccessFeature PaperArticle

Planar Harmonic and Monogenic Polynomials of Type A

by Charles F. Dunkl

Symmetry 2016, 8(10), 108; https://doi.org/10.3390/sym8100108 - 21 Oct 2016

Viewed by 3145

Harmonic polynomials of type A are polynomials annihilated by the Dunkl Laplacian associated to the symmetric group acting as a reflection group on

R^{N}

. The Dunkl operators are denoted by

T_{j}

for

1 \leq j \leq N

, and the [...] Read more.

Harmonic polynomials of type A are polynomials annihilated by the Dunkl Laplacian associated to the symmetric group acting as a reflection group on

R^{N}

. The Dunkl operators are denoted by

T_{j}

for

1 \leq j \leq N

, and the Laplacian

Δ_{κ} = \sum_{j = 1}^{N} T_{j}^{2}

. This paper finds the homogeneous harmonic polynomials annihilated by all

T_{j}

for

j > 2

. The structure constants with respect to the Gaussian and sphere inner products are computed. These harmonic polynomials are used to produce monogenic polynomials, those annihilated by a Dirac-type operator. Full article

(This article belongs to the Special Issue Symmetry in Orthogonal Polynomials)

911 KiB

Open AccessArticle

Scenario-Based Digital Forensics Challenges in Cloud Computing

by Erik Miranda Lopez, Seo Yeon Moon and Jong Hyuk Park

Symmetry 2016, 8(10), 107; https://doi.org/10.3390/sym8100107 - 20 Oct 2016

Cited by 17 | Viewed by 12417

Abstract

The aim of digital forensics is to extract information to answer the 5Ws (Why, When, Where, What, and Who) from the data extracted from the evidence. In order to achieve this, most digital forensic processes assume absolute control of digital evidence. However, in [...] Read more.

The aim of digital forensics is to extract information to answer the 5Ws (Why, When, Where, What, and Who) from the data extracted from the evidence. In order to achieve this, most digital forensic processes assume absolute control of digital evidence. However, in a cloud environment forensic investigation, this is not always possible. Additionally, the unique characteristics of cloud computing create new technical, legal and architectural challenges when conducting a forensic investigation. We propose a hypothetical scenario to uncover and explain the challenges forensic practitioners face during cloud investigations. Additionally, we also provide solutions to address the challenges. Our hypothetical case scenario has shown that, in the long run, better live forensic tools, development of new methods tailored for cloud investigations and new procedures and standards are indeed needed. Furthermore, we have come to the conclusion that forensic investigations biggest challenge is not technical but legal. Full article

(This article belongs to the Special Issue Symmetry in Secure Cyber World)

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1475 KiB

Open AccessArticle

Security Scheme Based on Parameter Hiding Technic for Mobile Communication in a Secure Cyber World

by Jong Hyuk Park, Hyungjoo Kim and Jungho Kang

Symmetry 2016, 8(10), 106; https://doi.org/10.3390/sym8100106 - 17 Oct 2016

Cited by 1 | Viewed by 4254

Abstract

Long Term Evolution (LTE) and Long Term Evolution-Advanced (LTE-A) support a better data transmission service than 3G dose and are globally commercialized technologies in a cyber world that is essential for constructing a future mobile environment, since network traffics have exponentially increased as [...] Read more.

Long Term Evolution (LTE) and Long Term Evolution-Advanced (LTE-A) support a better data transmission service than 3G dose and are globally commercialized technologies in a cyber world that is essential for constructing a future mobile environment, since network traffics have exponentially increased as people have started to use more than just one mobile device. However, when User Equipment (UE) is executing initial attach processes to access LTE networks, there is a vulnerability in which identification parameters like International Mobile Subscriber Identity (IMSI) and Radio Network Temporary Identities (RNTI) are transmitted as plain texts. It can threat various services that are commercialized therewith in a cyber world. Therefore, a security scheme is proposed in this paper where identification parameters can be securely transmitted and hidden in four cases where initial attach occurs between UE and Mobility Management Entity (MME). The proposed security scheme not only supports encrypted transmission of identification parameters but also mutual authentication between Evolved Node B (eNB) and MME to make a secure cyber world. Additionally, performance analysis results using an OPNET simulator showed the satisfaction of the average delay rate that is specified in LTE standards. Full article

(This article belongs to the Special Issue Symmetry in Secure Cyber World)

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242 KiB

Open AccessReview

Testing Lorentz and CPT Invariance with Neutrinos

by Jorge S. Díaz

Symmetry 2016, 8(10), 105; https://doi.org/10.3390/sym8100105 - 11 Oct 2016

Cited by 13 | Viewed by 4554

Abstract

Neutrino experiments can be considered sensitive tools to test Lorentz and CPT invariance. Taking advantage of the great variety of neutrino experiments, including neutrino oscillations, weak decays, and astrophysical neutrinos, the generic experimental signatures of the breakdown of these fundamental symmetries in the [...] Read more.

Neutrino experiments can be considered sensitive tools to test Lorentz and CPT invariance. Taking advantage of the great variety of neutrino experiments, including neutrino oscillations, weak decays, and astrophysical neutrinos, the generic experimental signatures of the breakdown of these fundamental symmetries in the neutrino sector are presented. Full article

(This article belongs to the Special Issue CPT Symmetry)

858 KiB

Open AccessArticle

A Search Complexity Improvement of Vector Quantization to Immittance Spectral Frequency Coefficients in AMR-WB Speech Codec

by Bing-Jhih Yao, Cheng-Yu Yeh and Shaw-Hwa Hwang

Symmetry 2016, 8(10), 104; https://doi.org/10.3390/sym8100104 - 30 Sep 2016

Cited by 4 | Viewed by 5059

Abstract

An adaptive multi-rate wideband (AMR-WB) code is a speech codec developed on the basis of an algebraic code-excited linear-prediction (ACELP) coding technique, and has a double advantage of low bit rates and high speech quality. This coding technique is widely used in modern [...] Read more.

An adaptive multi-rate wideband (AMR-WB) code is a speech codec developed on the basis of an algebraic code-excited linear-prediction (ACELP) coding technique, and has a double advantage of low bit rates and high speech quality. This coding technique is widely used in modern mobile communication systems for a high speech quality in handheld devices. However, a major disadvantage is that a vector quantization (VQ) of immittance spectral frequency (ISF) coefficients occupies a significant computational load in the AMR-WB encoder. Hence, this paper presents a triangular inequality elimination (TIE) algorithm combined with a dynamic mechanism and an intersection mechanism, abbreviated as the DI-TIE algorithm, to remarkably improve the complexity of ISF coefficient quantization in the AMR-WB speech codec. Both mechanisms are designed in a way that recursively enhances the performance of the TIE algorithm. At the end of this work, this proposal is experimentally validated as a superior search algorithm relative to a conventional TIE, a multiple TIE (MTIE), and an equal-average equal-variance equal-norm nearest neighbor search (EEENNS) approach. With a full search algorithm as a benchmark for search load comparison, this work provides a search load reduction above 77%, a figure far beyond 36% in the TIE, 49% in the MTIE, and 68% in the EEENNS approach. Full article

(This article belongs to the Special Issue Symmetry in Systems Design and Analysis)

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1666 KiB

Open AccessArticle

Cloud-Based Parameter-Driven Statistical Services and Resource Allocation in a Heterogeneous Platform on Enterprise Environment

by Sungju Lee and Taikyeong Jeong

Symmetry 2016, 8(10), 103; https://doi.org/10.3390/sym8100103 - 29 Sep 2016

Cited by 8 | Viewed by 5050

Abstract

A fundamental key for enterprise users is a cloud-based parameter-driven statistical service and it has become a substantial impact on companies worldwide. In this paper, we demonstrate the statistical analysis for some certain criteria that are related to data and applied to the [...] Read more.

A fundamental key for enterprise users is a cloud-based parameter-driven statistical service and it has become a substantial impact on companies worldwide. In this paper, we demonstrate the statistical analysis for some certain criteria that are related to data and applied to the cloud server for a comparison of results. In addition, we present a statistical analysis and cloud-based resource allocation method for a heterogeneous platform environment by performing a data and information analysis with consideration of the application workload and the server capacity, and subsequently propose a service prediction model using a polynomial regression model. In particular, our aim is to provide stable service in a given large-scale enterprise cloud computing environment. The virtual machines (VMs) for cloud-based services are assigned to each server with a special methodology to satisfy the uniform utilization distribution model. It is also implemented between users and the platform, which is a main idea of our cloud computing system. Based on the experimental results, we confirm that our prediction model can provide sufficient resources for statistical services to large-scale users while satisfying the uniform utilization distribution. Full article

(This article belongs to the Special Issue Symmetry in Systems Design and Analysis)

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5501 KiB

Open AccessArticle

A POCS Algorithm Based on Text Features for the Reconstruction of Document Images at Super-Resolution

by Fengmei Liang, Yajun Xu, Mengxia Zhang and Liyuan Zhang

Symmetry 2016, 8(10), 102; https://doi.org/10.3390/sym8100102 - 29 Sep 2016

Cited by 4 | Viewed by 4417

Abstract

In order to address the problem of the uncertainty of existing noise models and of the complexity and changeability of the edges and textures of low-resolution document images, this paper presents a projection onto convex sets (POCS) algorithm based on text features. The [...] Read more.

In order to address the problem of the uncertainty of existing noise models and of the complexity and changeability of the edges and textures of low-resolution document images, this paper presents a projection onto convex sets (POCS) algorithm based on text features. The current method preserves the edge details and smooths the noise in text images by adding text features as constraints to original POCS algorithms and converting the fixed threshold to an adaptive one. In this paper, the optimized scale invariant feature transform (SIFT) algorithm was used for the registration of continuous frames, and finally the image was reconstructed under the improved POCS theoretical framework. Experimental results showed that the algorithm can significantly smooth the noise and eliminate noise caused by the shadows of the lines. The lines of the reconstructed text are smoother and the stroke contours of the reconstructed text are clearer, and this largely eliminates the text edge vibration to enhance the resolution of the document image text. Full article

(This article belongs to the Special Issue Symmetry in Complex Networks II)

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3946 KiB

Open AccessArticle

Smartphone User Identity Verification Using Gait Characteristics

by Robertas Damaševičius, Rytis Maskeliūnas, Algimantas Venčkauskas and Marcin Woźniak

Symmetry 2016, 8(10), 100; https://doi.org/10.3390/sym8100100 - 29 Sep 2016

Cited by 65 | Viewed by 8315

Abstract

Smartphone-based biometrics offers a wide range of possible solutions, which could be used to authenticate users and thus to provide an extra level of security and theft prevention. We propose a method for positive identification of smartphone user’s identity using user’s gait characteristics [...] Read more.

Smartphone-based biometrics offers a wide range of possible solutions, which could be used to authenticate users and thus to provide an extra level of security and theft prevention. We propose a method for positive identification of smartphone user’s identity using user’s gait characteristics captured by embedded smartphone sensors (gyroscopes, accelerometers). The method is based on the application of the Random Projections method for feature dimensionality reduction to just two dimensions. Then, a probability distribution function (PDF) of derived features is calculated, which is compared against known user PDF. The Jaccard distance is used to evaluate distance between two distributions, and the decision is taken based on thresholding. The results for subject recognition are at an acceptable level: we have achieved a grand mean Equal Error Rate (ERR) for subject identification of 5.7% (using the USC-HAD dataset). Our findings represent a step towards improving the performance of gait-based user identity verification technologies. Full article

(This article belongs to the Special Issue Symmetry in Secure Cyber World)

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470 KiB

Open AccessArticle

Structural Distortion Stabilizing the Antiferromagnetic and Semiconducting Ground State of BaMn₂As₂

by Ekkehard Krüger

Symmetry 2016, 8(10), 99; https://doi.org/10.3390/sym8100099 - 28 Sep 2016

Cited by 4 | Viewed by 4264

Abstract

We report evidence that the experimentally found antiferromagnetic structure as well as the semiconducting ground state of BaMn

_{2}

As

_{2}

are caused by optimally-localized Wannier states of special symmetry existing at the Fermi level of BaMn

_{2}

As

_{2}

. In addition, [...] Read more.

We report evidence that the experimentally found antiferromagnetic structure as well as the semiconducting ground state of BaMn

_{2}

As

_{2}

are caused by optimally-localized Wannier states of special symmetry existing at the Fermi level of BaMn

_{2}

As

_{2}

. In addition, we find that a (small) tetragonal distortion of the crystal is required to stabilize the antiferromagnetic semiconducting state. To our knowledge, this distortion has not yet been established experimentally. Full article

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1702 KiB

Open AccessArticle

Maternal Stress Affects Fetal Growth but Not Developmental Instability in Rabbits

by Jessica Bots, Matteo Breno, Luc De Schaepdrijver and Stefan Van Dongen

Symmetry 2016, 8(10), 101; https://doi.org/10.3390/sym8100101 - 27 Sep 2016

Cited by 2 | Viewed by 4341

Abstract

Developmental instability (DI), often measured by fluctuating asymmetry (FA) or the frequency of phenodeviants (fPD), is thought to increase with stress. However, specifically for stressors of maternal origin, evidence of such negative associations with DI is scarce. Whereas effects of maternal stress on [...] Read more.

Developmental instability (DI), often measured by fluctuating asymmetry (FA) or the frequency of phenodeviants (fPD), is thought to increase with stress. However, specifically for stressors of maternal origin, evidence of such negative associations with DI is scarce. Whereas effects of maternal stress on DI have predominately been examined retroactively in humans, very little is known from experiments with well-defined stress levels in animal model systems. The aim of this study was to examine the effects of maternal exposure to three doses (plus a control) of a toxic compound affecting maternal condition on DI of their offspring in rabbits. Presence of maternal stress induced by the treatment was confirmed by a decrease in food consumption and weight gain of gravid females in the medium and high dose. Major abnormalities and mortality were unaffected by dose, suggesting the lack of toxic effects of the compound on the offspring. In spite of string maternal stress, offspring FA did not increase with dose. The treatment did lead to elevated fPD, but most were transient, reflecting growth retardation. Furthermore, a consistent association between fPD and FA was absent. These findings indicate that DI is not increased by maternal stress in this animal model. Full article

(This article belongs to the Special Issue Fluctuating Asymmetry 2016)

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Symmetry, Volume 8, Issue 10 (October 2016) – 10 articles

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