On equitorsion geodesic mappings of general affine connection spaces onto generalized Riemannian spaces

AbstractIn the papers Minčić (1973) [15], Minčić (1977) [16], several Ricci type identities are obtained by using non-symmetric affine connection. Four kinds of covariant derivatives appear in these identities.In the present work, we consider equitorsion geodesic mappings f of two spaces GAN and GR¯N, where GR¯N has a non-symmetric metric tensor, i.e. we study the case when GAN and GR¯N have the same torsion tensors at corresponding points. Such a mapping is called an equitorsion mapping Minčić (1997) [12], Stanković et al. (2010) [14], Stanković (in press) [13].The existence of a mapping of such type implies the existence of a solution of the fundamental equations. We find several forms of these fundamental equations. Among these forms a particularly important form is system of partial differential equations of Cauchy type

Quarter-symmetric connection on an almost Hermitian manifold and on a K\"ahler manifold

The paper observes an almost Hermitian manifold as an example of a generalized Riemannian manifold and examines the application of a quarter-symmetric connection on the almost Hermitian manifold. The almost Hermitian manifold with quarter-symmetric connection preserving the generalized Riemannian metric is actually the K\"ahler manifold. Observing the six linearly independent curvature tensors with respect to the quarter-symmetric connection, we construct tensors that do not depend on the quarter-symmetric connection generator. One of them coincides with the Weyl projective curvature tensor of symmetric metric $g$. Also, we obtain the relations between the Weyl projective curvature tensor and the holomorphically projective curvature tensor. Moreover, we examine the properties of curvature tensors when some tensors are hybrid

Thermodynamic Analysis of a Cascade Heat Pump Incorporated in High-Temperature Heating System

In this article is presented thermodynamic analysis of a cascade heat pump system designed for using in high-temperature heating systems The own thermodynamic model was built by using properties of working fluids from the Coo/Prop base. The cascade heat pump was designed to use ambient air as heat source with temperature t(amb )= -20 degrees C and for heating water in the high-temperature heating system up to 70 degrees C. The projected heating capacity of the cascade heat pump was 100 kW. The coefficient of performance (COP) of the cascade heat pump system due to use of different working mediums combinations in cycles of the cascade heat pump was investigated. For the best combination of working fluids (mediums) sub-cooling super-heating pressure loss in compressor's suction line, as well as exergy efficiency of the heat pump were analysed as a function of the temperature of the cascade heat exchanger

Thermodynamic Analysis of a Cascade Heat Pump Incorporated in High-Temperature Heating System

In this article is presented thermodynamic analysis of a cascade heat pump system designed for using in high-temperature heating systems The own thermodynamic model was built by using properties of working fluids from the Coo/Prop base. The cascade heat pump was designed to use ambient air as heat source with temperature t(amb )= -20 degrees C and for heating water in the high-temperature heating system up to 70 degrees C. The projected heating capacity of the cascade heat pump was 100 kW. The coefficient of performance (COP) of the cascade heat pump system due to use of different working mediums combinations in cycles of the cascade heat pump was investigated. For the best combination of working fluids (mediums) sub-cooling super-heating pressure loss in compressor's suction line, as well as exergy efficiency of the heat pump were analysed as a function of the temperature of the cascade heat exchanger

Equitorsion holomorphically projective mappings of generalized Kählerian space of the first kind

summary:In this paper we define generalized Kählerian spaces of the first kind $(G\underset 1K_N)$ given by (2.1)--(2.3). For them we consider hollomorphically projective mappings with invariant complex structure. Also, we consider equitorsion geodesic mapping between these two spaces ($G\underset 1K_N$ and $G\underset 1{\overline K}_N$) and for them we find invariant geometric objects

IDENTITIES FOR CURVATURE TENSORS IN GENERALIZED FINSLER SPACE

Abstract In the some previous works we have obtained several curvature tensors in the generalized Finsler space GF N (the space with non-symmetric basic tensor and non-symmetric connection in Rund's sence). In this work we study identities for the mentioned tensors (the antisymmetry with respect of two indices, the cyclic symmetry, the symmetry with respect of pairs of indices)

Current state and perspective of water management policy in terms of climate change: Case study of the Velika Morava River

The purpose of this paper is to set out the policy guidelines and recommendations to harmonise the Serbian water legislation with European Union standards in the area of water system management as impacted by climate change. The EU Water Framework Directive is analysed in the context of implementation of the integrated water management policy presented in the Serbian Water Law (2010), as well as the National Water Management Strategy (2016). It has been found that the water management legislation that deals with the impact of climate change on water resources is incomplete. Although there are numerous challenges related to research of climate change and water systems, water policy and legal aspects cannot be neglected. The so-called soft law instruments represented in a form of strategy documents could be a valuable response in terms of an adaptive and integrated water policy approach. The research is applied to a case study of the Velika Morava River Basin, at Ljubicevski Most hydrological station. Long-term projections suggest a decrease in annual precipitation levels and annual flows up to the year 2100 for climatic scenarios A1B and A2, accompanied by a rapid increase in air temperatures. This study proposes a water management policy and provides recommendations for the Velika Morava River Basin as impacted by climate change, according to the European Union legislation

Study of vacuum and freeze drying of bee honey

The aim of this research is to study the drying kinetics of vacuum-dried and freeze-dried bee honey produced from two different varieties: Sunflower honey (Helianthus Annuus L.) and Acacia honey (Robinia pseudo acacia L.). Vacuum drying treatments were carried out with the honey samples' initial temperatures of +25 degrees C, -20 degrees C, and -40 degrees C. Water content, total soluble solids, as well as the water activity of fresh and dried honey samples were determined. Freeze-drying of bee honey with initial sample temperature of -40 degrees C has resulted in shorter drying time (7-9 hours), moisture content (10%-12%), water activity (0.405-0.427 aW) and effective moisture diffusivity coefficient (8.26.10-7-9.51.0-7 m(2)/s). The high-performance liquid chromatography method was used when analyzing the impact that drying pre-treatments had on honey quality. The application of pre-treatments has led to an increase in hydroxy-methyl-furfural by 39-71%, and a decrease in diastase activity by 17-36%, all compared to fresh honey samples. The solutions of Verma model proved to be the best fit with the experimental results

Study of vacuum and freeze drying of bee honey

The aim of this research is to study the drying kinetics of vacuum-dried and freeze-dried bee honey produced from two different varieties: Sunflower honey (Helianthus Annuus L.) and Acacia honey (Robinia pseudo acacia L.). Vacuum drying treatments were carried out with the honey samples' initial temperatures of +25 degrees C, -20 degrees C, and -40 degrees C. Water content, total soluble solids, as well as the water activity of fresh and dried honey samples were determined. Freeze-drying of bee honey with initial sample temperature of -40 degrees C has resulted in shorter drying time (7-9 hours), moisture content (10%-12%), water activity (0.405-0.427 aW) and effective moisture diffusivity coefficient (8.26.10-7-9.51.0-7 m(2)/s). The high-performance liquid chromatography method was used when analyzing the impact that drying pre-treatments had on honey quality. The application of pre-treatments has led to an increase in hydroxy-methyl-furfural by 39-71%, and a decrease in diastase activity by 17-36%, all compared to fresh honey samples. The solutions of Verma model proved to be the best fit with the experimental results