Stanilov-Tsankov-Videv Theory

We survey some recent results concerning Stanilov-Tsankov-Videv theory, conformal Osserman geometry, and Walker geometry which relate algebraic properties of the curvature operator to the underlying geometry of the manifold.Comment: This is a contribution to the Proceedings of the 2007 Midwest Geometry Conference in honor of Thomas P. Branson, published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA

Complete curvature homogeneous pseudo-Riemannian manifolds

We exhibit 3 families of complete curvature homogeneous pseudo-Riemannian manifolds which are modeled on irreducible symmetric spaces and which are not locally homogeneous. All of the manifolds have nilpotent Jacobi operators; some of the manifolds are, in addition, Jordan Osserman and Jordan Ivanov-Petrova.Comment: Update paper to fix misprints in original versio

Examples of signature (2,2) manifolds with commuting curvature operators

We exhibit Walker manifolds of signature (2,2) with various commutativity properties for the Ricci operator, the skew-symmetric curvature operator, and the Jacobi operator. If the Walker metric is a Riemannian extension of an underlying affine structure A, these properties are related to the Ricci tensor of A

5G-CLARITY : 5G-advanced private networks integrating 5GNR, WiFi, and LiFi

The future of the manufacturing industry highly depends on digital systems that transform existing production and monitoring systems into autonomous systems fulfilling stringent requirements in terms of availability, reliability, security, low latency, and positioning with high accuracy. In order to meet such requirements, private 5G networks are considered as a key enabling technology. In this article, we introduce the 5G-CLARITY system that integrates 5GNR, WiFi, and LiFi access networks, and develops novel management enablers to operate 5G-Advanced private networks. We describe three core features of 5G-CLARITY, including a multi-connectivity framework, a high-precision positioning server, and a management system to orchestrate private network slices. These features are evaluated by means of packet-level simulations and an experimental testbed demonstrating the ability of 5G-CLARITY to police access network traffic, to achieve centimeter-level positioning accuracy, and to provision private network slices in less than one minute

In vitro gas production of different feeds and feed ingredients at ruminants

Abstract. Investigation for determining the amount of in vitro gas production after feeding different groups of forages was performed at the Agricultural Institute- ® Stara Zagora. Forages from different regions were collected and analyzed for in vitro gas production at 24 h and 48 h by Ankom Technology . The following parameters of the tested forages were determinated: Neutral detergent fibre (NDF, %), Acid detergent fibre (ADF, %), Digestibility of dry matter (DDM, %), Dry matter intakе (DMI, %) and Relative Feed Value (RFV, %). RFV was calculated on the base of DDM and DMI in comparison with alfalfa biomass in flowering stage. Collected feeds (46 samples) were divided in 11 groups on the base of their composition and structure - fibre component content. Depending on the amount of gas production forages can be divided in 3 groups: 1) Grain feeds generating the highest amount of gas - average 387.93 ml/g DM; 2) Combined feeds, fresh forages, complete feed mixtures - average 213.87- 245.15 ml/g DM 3) Hay, silage, straw, complete feed mixtures + bioadditives - average 115.06 - 208.34 ml/g DM. Intensity of gas production in grain feeds was higher at 24 h, while on the opposite, was higher at 48 h in roughage feeds due to the different speed of degradation of feeds - concentrated had a very intensive and quick degradation, roughages - slow degradation. Supplementation of combined feeds with bioadditives Rumanol, Biolife, Bibor decreased the amount of gas production by 9.87% - 29.05%