30 research outputs found
New Hermitian self-dual MDS or near-MDS codes over finite fields
A linear code over a finite field is called Hermitian self-dual if the code is self-dual under the Hermitian inner-product. The Hermitian self-dual code is called MDS or near-MDS if the code attains or almost attains the Singleton bound. In this paper we construct new Hermitian self-dual MDS or near-MDS codes over and of length up to 14
Linear Continuous Sliding Mode-based Attitude Controller with Modified Rodrigues Parameters Feedback
This paper studies an attitude control system design based on modified
Rodrigues parameters feedback. It employs a linear continuous sliding mode
controller. The sliding mode controller is able to bring the existence of the
sliding motion asymptotically. Besides, the attitude control system equilibrium
point is proved to have an asymptotic stability guarantee through further
analysis. This stability analysis is conducted since the sliding mode existence
on the designed sliding surface does not imply the stability guarantee of the
system's equilibrium. This paper ends with some numerical examples that confirm
the effectiveness of the designed attitude control system
Asymptotic Stability of Quaternion-based Attitude Control System with Saturation Function
In the design of attitude control, rotational motion of the spacecraft is usually considered as a rotation of rigid body. Rotation matrix parameterization using quaternion can represent globally attitude of a rigid body rotational motions. However, the representation is not unique hence implies difficulties on the stability guarantee. This paper presents asymptotically stable analysis of a continuous scheme of quaternion-based control system that has saturation function. Simulations run show that the designed system applicable for a zero initial angular velocity case and a non-zero initial angular velocity case due to utilization of deadzone function as an element of the defined constraint in the stability analysis
PENGARUH DIAMETER PENGEROLAN DINGIN TERHADAP KEKUATAN BENDING BAJA KARBON RENDAH
Baja St 41 merupakan baja karbon rendah yang mengandung karbon dibawah 0,30% banyak diaplikasikan untuk konstruksi umum. Pembetukan benda dengan pengerolan banyak dilakukan untuk pembuatan bejana maupun konstruksi penguatan dengan plat baja .Pada penelitian ini dilakukan proses pengerolan dingin, baja AISI 1015 setebal 7,65 mm dengan radius: 500, 1000, 2000 dan 3000 mm. Pengujian yang dilakukan adalah uji komposisi kimia, uji kekerasan uji struktur mikro , dan uji kekuatan bending dengan arah berlawanan dari arah pengerolan. Dari hasil pengujian tersebut dapat disimpulkan bahwa pengerolan akan meningkatkan kekuatan bending sampai pada ukuran tertentu. Setelah Iewat batas tertentu maka bahan akan luluh sehingga menurunkan kekerasan serta kekuatan bendingnya.Kata kunci: Baja St 41, Rolling, Ferit, Kekuatan Bendin
Skew cyclic codes over with derivation: structural properties and computational results
In this work, we study a class of skew cyclic codes over the ring
where with an automorphism
and a derivation namely codes as modules over a skew
polynomial ring whose multiplication is defined
using an automorphism and a derivation We
investigate the structures of a skew polynomial ring
We define -cyclic codes as a
generalization of the notion of cyclic codes. The properties of
-cyclic codes as well as dual -cyclic codes
are derived. As an application, some new linear codes over with
good parameters are obtained by Plotkin sum construction, also via a Gray map
as well as residue and torsion codes of these codes.Comment: 25 page
A general family of Plotkin-optimal two-weight codes over
We obtain all possible parameters of Plotkin-optimal two-Lee weight
projective codes over together with their weight distributions.
We show the existence of codes with these parameters as well as their weight
distributions by constructing an infinite family of two-weight codes.
Previously known codes constructed by Shi et al. (\emph{Des Codes Cryptogr.}
{\bf 88}(3):1-13, 2020) can be derived as a special case of our results. We
also prove that the Gray image of any Plotkin-optimal two-Lee weight projective
codes over has the same parameters and weight distribution as
some two-weight binary projective codes of type SU1 in the sense of Calderbank
and Kantor (\emph{Bull. Lond. Math. Soc.} {\bf 18}:97-122, 1986).Comment: 17 pages, finlar versio