• Title/Summary/Keyword: skew

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ON GENERALIZATIONS OF SKEW QUASI-CYCLIC CODES

  • Bedir, Sumeyra;Gursoy, Fatmanur;Siap, Irfan
    • Bulletin of the Korean Mathematical Society
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    • v.57 no.2
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    • pp.459-479
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    • 2020
  • In the last two decades, codes over noncommutative rings have been one of the main trends in coding theory. Due to the fact that noncommutativity brings many challenging problems in its nature, still there are many open problems to be addressed. In 2015, generator polynomial matrices and parity-check polynomial matrices of generalized quasi-cyclic (GQC) codes were investigated by Matsui. We extended these results to the noncommutative case. Exploring the dual structures of skew constacyclic codes, we present a direct way of obtaining parity-check polynomials of skew multi-twisted codes in terms of their generators. Further, we lay out the algebraic structures of skew multipolycyclic codes and their duals and we give some examples to illustrate the theorems.

ON COEFFICIENTS OF NILPOTENT POLYNOMIALS IN SKEW POLYNOMIAL RINGS

  • Nam, Sang Bok;Ryu, Sung Ju;Yun, Sang Jo
    • Korean Journal of Mathematics
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    • v.21 no.4
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    • pp.421-428
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    • 2013
  • We observe the basic structure of the products of coefficients of nilpotent (left) polynomials in skew polynomial rings. This study consists of a process to extend a well-known result for semi-Armendariz rings. We introduce the concept of ${\alpha}$-skew n-semi-Armendariz ring, where ${\alpha}$ is a ring endomorphism. We prove that a ring R is ${\alpha}$-rigid if and only if the n by n upper triangular matrix ring over R is $\bar{\alpha}$-skew n-semi-Armendariz. This result are applicable to several known results.

The timing do-skew modeling and design in a high speed digital system (고속 디지털 시스템에서 전달 시간차의 보정 모델링 및 구현)

  • Oh, Kwang-Suhk
    • Proceedings of the KIEE Conference
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    • 2002.11c
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    • pp.601-604
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    • 2002
  • In this paper, the timing do-skew modeling for a high speed logic tester channels is developed. The time delay of each channel in a logic tester are different from other channels and it can produce timing error in a test. To get the best timing accuracy in the test with a logic tester, the timing skew must be compensated. The timing skew of channels is due to the difference of time delay of pin-electronics devices composing channels and length of metal line placed on PCB. The expected timing difference of channels can be calculated according to the specifications of pin electronics devices and strip line modeling of PCB. With the calculated delay time, the timing skew compensation circuit has been designed. With the timing skew compensation circuit, the timing calibration of a logic tester can be peformed easily and automatically without other time measuring instruments. The calibration method can then be directly applied to logic testers in mass production lines.

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The skew-t censored regression model: parameter estimation via an EM-type algorithm

  • Lachos, Victor H.;Bazan, Jorge L.;Castro, Luis M.;Park, Jiwon
    • Communications for Statistical Applications and Methods
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    • v.29 no.3
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    • pp.333-351
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    • 2022
  • The skew-t distribution is an attractive family of asymmetrical heavy-tailed densities that includes the normal, skew-normal and Student's-t distributions as special cases. In this work, we propose an EM-type algorithm for computing the maximum likelihood estimates for skew-t linear regression models with censored response. In contrast with previous proposals, this algorithm uses analytical expressions at the E-step, as opposed to Monte Carlo simulations. These expressions rely on formulas for the mean and variance of a truncated skew-t distribution, and can be computed using the R library MomTrunc. The standard errors, the prediction of unobserved values of the response and the log-likelihood function are obtained as a by-product. The proposed methodology is illustrated through the analyses of simulated and a real data application on Letter-Name Fluency test in Peruvian students.

On n-skew Lie Products on Prime Rings with Involution

  • Ali, Shakir;Mozumder, Muzibur Rahman;Khan, Mohammad Salahuddin;Abbasi, Adnan
    • Kyungpook Mathematical Journal
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    • v.62 no.1
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    • pp.43-55
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    • 2022
  • Let R be a *-ring and n ≥ 1 be an integer. The objective of this paper is to introduce the notion of n-skew centralizing maps on *-rings, and investigate the impact of these maps. In particular, we describe the structure of prime rings with involution '*' such that *[x, d(x)]n ∈ Z(R) for all x ∈ R (for n = 1, 2), where d : R → R is a nonzero derivation of R. Among other related results, we also provide two examples to prove that the assumed restrictions on our main results are not superfluous.

Skew Correction of Business Card Images for PDA Application (PDA 응용을 위한 명함 영상의 회전 보정)

  • 박준효;장익훈;김남철
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.12C
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    • pp.1225-1238
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    • 2003
  • We present an efficient algorithm for skew correction of business card images obtained by a PDA (personal digital assistant) camera. The proposed method is composed of four parts: block adaptive binarization (BAB), stripe generation, skew angle calculation, and image rotation. In the BAB, an input image is binarized block by block so as to lessen the effect of irregular illumination and shadow over the input image. In the stripe generation, character string clusters are generated merging adjacent characters and their strings, and then only clusters useful for skew angle calculation are output as stripes. In the skew angle calculation, the direction angles of the stripes are calculated using their central moments and then the skew angle of the input image is determined averaging the direction angles. In the image rotation, the input image is rotated by the skew angle. Experimental results shows that the proposed method yields skew correction rates of about 93% for test images of several types of business cards acquired by a PDA under various surrounding conditions.

Free vibration and static analysis of functionally graded skew magneto-electro-elastic plate

  • Kiran, M.C.;Kattimani, S.C.
    • Smart Structures and Systems
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    • v.21 no.4
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    • pp.493-519
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    • 2018
  • This article presents a finite element (FE) model to assess the free vibration and static response of a functionally graded skew magneto-electro-elastic (FGSMEE) plate. Through the thickness material grading of FGSMEE plate is achieved using power law distribution. The coupled constitutive equations along with the total potential energy approach are used to develop the FE model of FGSMEE plate. The transformation matrix is utilized in bringing out the element matrix corresponding to the global axis to a local axis along the skew edges to specify proper boundary conditions. The effect of skew angle on the natural frequency of an FGSMEE plate is analysed. Further, the study includes the evaluation of the static behavior of FGSMEE plate for various skew angles. The influence of skew angle on the primary quantities such as displacements, electric potential, and magnetic potential, and secondary quantities such as stresses, electric displacement and magnetic induction is studied in detail. In addition, the effect of power-law gradient, thickness ratio, boundary conditions and aspect ratio on the free vibration and static response characteristics of FGSMEE plate has been investigated.

Realtime Clock Skew Estimator for Time Synchronization in Wireless Sensor Networks of WUSB and WBAN (무선 센서네트워크에서의 시각동기를 위한 실시간 클럭 스큐 추정)

  • Hur, Kyeong
    • Journal of Korea Multimedia Society
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    • v.15 no.11
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    • pp.1391-1398
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    • 2012
  • Time synchronization is crucial in wireless sensor networks such as Wireless USB and WBAN for diverse purposes from the MAC to the application layer. This paper proposes online clock skew estimators to achieve energy-efficient time synchronization for wireless sensor networks. By using recursive least squares estimators, we not only reduce the amount of data which should be stored locally in a table at each sensor node, but also allow offset and skew compensations to be processed simultaneously. Our skew estimators can be easily integrated with traditional offset compensation schemes. The results of simulation and experiment show that the accuracy of time synchronization can be greatly improved through our skew compensation algorithm.

Time domain buffeting analysis of long suspension bridges under skew winds

  • Liu, G.;Xu, Y.L.;Zhu, L.D.
    • Wind and Structures
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    • v.7 no.6
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    • pp.421-447
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    • 2004
  • This paper presents a time domain approach for predicting buffeting response of long suspension bridges under skew winds. The buffeting forces on an oblique strip of the bridge deck in the mean wind direction are derived in terms of aerodynamic coefficients measured under skew winds and equivalent fluctuating wind velocities with aerodynamic impulse functions included. The time histories of equivalent fluctuating wind velocities and then buffeting forces along the bridge deck are simulated using the spectral representation method based on the Gaussian distribution assumption. The self-excited forces on an oblique strip of the bridge deck are represented by the convolution integrals involving aerodynamic impulse functions and structural motions. The aerodynamic impulse functions of self-excited forces are derived from experimentally measured flutter derivatives under skew winds using rational function approximations. The governing equation of motion of a long suspension bridge under skew winds is established using the finite element method and solved using the Newmark numerical method. The proposed time domain approach is finally applied to the Tsing Ma suspension bridge in Hong Kong. The computed buffeting responses of the bridge under skew winds during Typhoon Sam are compared with those obtained from the frequency domain approach and the field measurement. The comparisons are found satisfactory for the bridge response in the main span.

Bending analysis of a micro sandwich skew plate using extended Kantorovich method based on Eshelby-Mori-Tanaka approach

  • Rajabi, Javad;Mohammadimehr, Mehdi
    • Computers and Concrete
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    • v.23 no.5
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    • pp.361-376
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    • 2019
  • In this research, bending analysis of a micro sandwich skew plate with isotropic core and piezoelectric composite face sheets reinforced by carbon nanotube on the elastic foundations are studied. The classical plate theory (CPT) are used to model micro sandwich skew plate and to apply size dependent effects based on modified strain gradient theory. Eshelby-Mori-Tanaka approach is considered for the effective mechanical properties of the nanocomposite face sheets. The governing equations of equilibrium are derived using minimum principle of total potential energy and then solved by extended Kantorovich method (EKM). The effects of width to thickness ratio and length to width of the sandwich plate, core-to-face sheet thickness ratio, the material length scale parameters, volume fraction of CNT, the angle of skew plate, different boundary conditions and types of cores on the deflection of micro sandwich skew plate are investigated. One of the most important results is the reduction of the deflection by increasing the angle of the micro sandwich skew plate and decreasing the deflection by decreasing the thickness of the structural core. The results of this research can be used in modern construction in the form of reinforced slabs or stiffened plates and also used in construction of bridges, the wing of airplane.