Results 31 to 40 of about 567 (106)

On Quasi‐Hermitian Varieties in Even Characteristic and Related Orthogonal Arrays

Journal of Combinatorial Designs, Volume 33, Issue 3, Page 109-122, March 2025.
ABSTRACT In this article, we study the BM quasi‐Hermitian varieties, laying in the three‐dimensional Desarguesian projective space of even order. After a brief investigation of their combinatorial properties, we first show that all of these varieties are projectively equivalent, exhibiting a behavior which is strikingly different from what happens in ...
Angela Aguglia, Luca Giuzzi, Alessandro Montinaro, Viola Siconolfi   +3 more
wiley   +1 more source

Conformal Vector Fields on Doubly Warped Product Manifolds and Applications

Advances in Mathematical Physics, Volume 2016, Issue 1, 2016., 2016
This article aimed to study and explore conformal vector fields on doubly warped product manifolds as well as on doubly warped spacetime. Then we derive sufficient conditions for matter and Ricci collineations on doubly warped product manifolds. A special attention is paid to concurrent vector fields.
H. K. El-Sayied, Sameh Shenawy, Noha Syied, Andrei Moroianu   +3 more
wiley   +1 more source

Proper Matter Collineations of Plane Symmetric Spacetimes [PDF]

, 2006
We investigate matter collineations of plane symmetric spacetimes when the energy-momentum tensor is degenerate. There exists three interesting cases where the group of matter collineations is finite-dimensional.
Guo Z. K., Ratra B., Sen A., Sen A., Sen A., WEI WANG, YING SHAO, YUAN-XING GUI   +7 more
core   +4 more sources

2‐Conformal Vector Fields on the Model Sol Space and Hyperbolic Ricci Solitons

Journal of Mathematics, Volume 2025, Issue 1, 2025.
In this study, we present the notion of 2‐conformal vector fields on Riemannian and semi‐Riemannian manifolds, which are an extension of Killing and conformal vector fields. Next, we provide suitable vector fields in Sol space that are 2‐conformal. A few implications of 2‐conformal vector fields in hyperbolic Ricci solitons are investigated.
Rawan Bossly, Ghodratallah Fasihi-Ramandi, Mohd Danish Siddiqi, Antonio Masiello   +3 more
wiley   +1 more source

Paracomplex Paracontact Pseudo‐Riemannian Submersions

Geometry, Volume 2014, Issue 1, 2014., 2014
We introduce the notion of paracomplex paracontact pseudo‐Riemannian submersions from almost para‐Hermitian manifolds onto almost paracontact metric manifolds. We discuss the transference of structures on total manifolds and base manifolds and provide some examples.
S. S. Shukla, Uma Shankar Verma, Bennett Palmer   +2 more
wiley   +1 more source

symmetries of the Ricci tensor of static space times with maximal symmetric transverse spaces

, 2006
Static space times with maximal symmetric transverse spaces are classified according to their Ricci collineations. These are investigated for non-degenerate Ricci tensor ($det.(R_{\alpha}) \neq 0$).
A.Z. Petro, Cai Rong-Gen, G.H. Katzin, G.H. Katzin, M Akbar   +4 more
core   +2 more sources

Multivariate Methods Based Soft Measurement for Wine Quality Evaluation

Abstract and Applied Analysis, Volume 2014, Issue 1, 2014., 2014
Soft measurement is a new, developing, and promising industry technology and has been widely used in the industry nowadays. This technology plays a significant role especially in the case where some key variables are difficult to be measured by traditional measurement methods.
Shen Yin, Lei Liu, Xin Gao, Hamid Reza Karimi, Josep M. Rossell   +4 more
wiley   +1 more source

Geometric equations of state in Friedmann-Lema\^{i}tre universes admitting matter and Ricci Collineations

, 2003
As a rule in General Relativity the spacetime metric fixes the Einstein tensor and through the Field Equations (FE) the energy-momentum tensor. However one cannot write the FE explicitly until a class of observers has been considered.
Apostolopoulos, Pantelis S., Tsamparlis, Michael   +1 more
core   +1 more source

Curvature collineations on Lie algebroid structure

, 2014
Considering prolongation of a Lie algebroid equipped with a spray, defining some classical tensors, we show that a Lie symmetry of a spray is a curvature collineation for these tensors.
Arcus, C. M., Peyghan, E., Sharahi, E.
openaire   +2 more sources

Conformal Ricci collineations of static spherically symmetric spacetimes

, 2010
Conformal Ricci collineations of static spherically symmetric spacetimes are studied. The general form of the vector fields generating conformal Ricci collineations is found when the Ricci tensor is non-degenerate, in which case the number of independent
Asghar Qadir, Bokhari A H, Camci U, Duggal K L, K Saifullah, Keane A J, Maartens R, Qadir A, Stephani H, Ugur Camci, Ziad M   +10 more
core   +1 more source