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298 result(s) for "Hristov, P."
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ENABLING CITY DIGITAL TWINS THROUGH URBAN LIVING LABS
The population density in urban areas is rapidly rising, leading to a constant need for new infrastructure and services for citizens. To reduce the time to implementation and optimise the monetary cost of various solutions, the plans and policies of local authorities and stakeholders would benefit from undergoing a series of virtual stress tests. To this end, prescriptive and predictive technologies are widely adopted to optimise city planning and to understand the urban processes and environment such as air pollution and transportation. Nevertheless, holistic sandboxes tightly integrated with cities are still largely lacking. The city digital twin is a promising concept that provides a tool for exploration of new solutions in a controlled environment before their deployment. The digital twin is a virtual replica of the real city, which collects data from the infrastructure, processes and services using not only the available systems, but also purposely built connected devices and sensors. In this context, the establishment of urban living labs facilitates the monitoring and understanding of urban processes and enriches the digital twin with highly-relevant data. This paper presents an urban living lab, under deployment in the district of Lozenets in Sofia, Bulgaria. It is part of a larger initiative for developing a city digital twin of Sofia to support the design, exploration, and experimentation of different solutions. The living lab is equipped with sensors for monitoring air quality, atmospheric parameters, noise pollution and pedestrian flows. In addition, a Light Detection and Ranging (LiDAR) system is realised as an edge computing facility at one of the busiest intersections of the district. Along with the equipment, the paper describes the architecture and components of the platform for data collection, storage, processing, and visualization. Finally, high-priority studies are presented, and their demographic and economic impact is discussed.
TOWARDS ENERGY ATLAS OF SOFIA CITY IN BULGARIA
This paper proposes the first energy atlas of Sofia in Bulgaria. The research uses a geographical information system (GIS) approach and a statistical tolerance methodology to estimate building energy consumption. The buildings were classified into ten categories, and tolerance intervals were computed, which provide a distribution-free summary for the consumption in each class, suitable for spatial visualisation. GIS is used to classify and visualise the results. The results show a clear contrast in the energy consumption between buildings in highly urbanised areas and those in the suburbs. It was found that the high energy consumption belongs to the areas where the shopping, commercial, industrial and sports buildings are located and already developed. The energy consumption bounds were used to enrich a semantic 3D city model of Sofia. This model can be used for further analysis of energy supply, climate change, urban heat islands, and urban health as well as for calculating the climate scenarios. An extensive outline of the utility and directions for future development of the atlas are provided.
Energy gains at daily periodic changes of the azimuths of PV modules in north-east Bulgaria
The higher efficiency of tracking photovoltaic systems is an indisputable fact and computational methods of the respective energy gains are well known. However the investments in the tracking systems are higher in comparison to the fixed ones due to the needs of additional equipment and automation systems. An options of periodical change of the azimuth of PV modules at single axis solar trackers and the correspondent incident solar energy are studied in this paper. An approach for numerical determination of the daily periods of cyclic rotations of the trackers and the subsequent electricity production is developed. It was applied to estimate the energy gains at such cyclic changes of a PV system in ceramic factory in Bulgaria.
Measurement of the form factors of charged kaon semileptonic decays
A bstract A measurement of the form factors of charged kaon semileptonic decays is presented, based on 4.4 × 10 6 K ± → π 0 e ± ν e ( K e 3 ± ) and 2.3 × 10 6 K ± → π 0 μ ± ν μ ( K μ 3 ± ) decays collected in 2004 by the NA48/2 experiment. The results are obtained with improved precision as compared to earlier measurements. The combination of measurements in the K e 3 ± and K μ 3 ± modes is also presented.
Phylogeny of hymenolepidids (Cestoda: Cyclophyllidea) from mammals: sequences of 18S rRNA and COI genes confirm major clades revealed by the 28S rRNA analyses
The aim of the study is to test a hypothesis for the phylogenetic relationships among mammalian hymenolepidid tapeworms, based on partial (D1–D3) nuclear 28S ribosomal RNA (rRNA) genes, by estimating new molecular phylogenies for the group based on partial mitochondrial cytochrome c oxidase I (COI) and nuclear 18S rRNA genes, as well as a combined analysis using all three genes. New sequences of COI and 18S rRNA genes were obtained for Coronacanthus integrus, C. magnihamatus, C. omissus, C. vassilevi, Ditestolepis diaphana, Lineolepis scutigera, Spasskylepis ovaluteri, Staphylocystis tiara, S. furcata, S. uncinata, Vaucherilepis trichophorus and Neoskrjabinolepis sp. The phylogenetic analyses confirmed the major clades identified by Haukisalmi et al. (Zoologica Scripta 39: 631–641, 2010): Ditestolepis clade, Hymenolepis clade, Rodentolepis clade and Arostrilepis clade. While the Ditestolepis clade is associated with soricids, the structure of the other three clades suggests multiple evolutionary events of host switching between shrews and rodents. Two of the present analyses (18S rRNA and COI genes) show that the basal relationships of the four mammalian clades are branching at the same polytomy with several hymenolepidids from birds (both terrestrial and aquatic). This may indicate a rapid radiation of the group, with multiple events of colonizations of mammalian hosts by avian parasites.
New high statistics measurement of Ke4 decay form factors and ππ scattering phase shifts
We report results from a new measurement of the K e4 decay K ± →π + π - e ± ν by the NA48/2 collaboration at the CERN SPS, based on a partial sample of more than 670 000 K e4 decays in both charged modes collected in 2003. The form factors of the hadronic current (F,G,H) and ππ phase difference (δ=δ s -δ p ) have been measured in ten independent bins of the ππ mass spectrum to investigate their variation. A sizeable acceptance at large ππ mass, a low background and a very good resolution contribute to an improved experimental accuracy, a factor two better than in the previous measurement, when extracting the ππ scattering lengths a 0 0 and a 0 2 . Under the assumption of isospin symmetry and using numerical solutions of the Roy equations, the following values are obtained in the plane (a 0 0 ,a 0 2 ): a 0 0 =0.233±0.016stat±0.007syst,a 0 2 =-0.0471±0.011stat±0.004syst. The presence of potentially large isospin effects is also considered and will allow comparison with precise predictions from Chiral Perturbation Theory.
Federated data storage and management infrastructure
The Large Hadron Collider (LHC)' operating at the international CERN Laboratory in Geneva, Switzerland, is leading Big Data driven scientific explorations. Experiments at the LHC explore the fundamental nature of matter and the basic forces that shape our universe. Computing models for the High Luminosity LHC era anticipate a growth of storage needs of at least orders of magnitude; it will require new approaches in data storage organization and data handling. In our project we address the fundamental problem of designing of architecture to integrate a distributed heterogeneous disk resources for LHC experiments and other data- intensive science applications and to provide access to data from heterogeneous computing facilities. We have prototyped a federated storage for Russian T1 and T2 centers located in Moscow, St.-Petersburg and Gatchina, as well as Russian CERN federation. We have conducted extensive tests of underlying network infrastructure and storage endpoints with synthetic performance measurement tools as well as with HENP-specific workloads, including the ones running on supercomputing platform, cloud computing and Grid for ALICE and ATLAS experiments. We will present our current accomplishments with running LHC data analysis remotely and locally to demonstrate our ability to efficiently use federated data storage experiment wide within National Academic facilities for High Energy and Nuclear Physics as well as for other data-intensive science applications, such as bio-informatics.
ALFA: The new ALICE-FAIR software framework
The commonalities between the ALICE and FAIR experiments and their computing requirements led to the development of large parts of a common software framework in an experiment independent way. The FairRoot project has already shown the feasibility of such an approach for the FAIR experiments and extending it beyond FAIR to experiments at other facilities[1, 2]. The ALFA framework is a joint development between ALICE Online- Offline (O2) and FairRoot teams. ALFA is designed as a flexible, elastic system, which balances reliability and ease of development with performance using multi-processing and multithreading. A message- based approach has been adopted; such an approach will support the use of the software on different hardware platforms, including heterogeneous systems. Each process in ALFA assumes limited communication and reliance on other processes. Such a design will add horizontal scaling (multiple processes) to vertical scaling provided by multiple threads to meet computing and throughput demands. ALFA does not dictate any application protocols. Potentially, any content-based processor or any source can change the application protocol. The framework supports different serialization standards for data exchange between different hardware and software languages.
Effectiveness of glycerin-oxalic acid strips and essential oils in controlling Varroa destructor in honeybee
The decline in the bee colony strength due to high levels of  infestations necessitates the development of new control methods. This study evaluates the effectiveness of glycerin-oxalic acid strips and essential oils in managing . The experiment was conducted in 2022 at the experimental apiary in Debelec, part of the Institute of Animal Husbandry in Kostinbrod. Six experimental groups, each treated with a different preparation, were compared to a control group of untreated colonies. Treatments included Beevital Hiveclean (20 ml per colony), Varro Red (2 ml per frame), ammonium nitrate strips (1.3 mm), glycerin-oxalic acid strips (1.3 mm), and glycerin-oxalic acid strips of paper-cellulose (2.3 mm) or cellulose-cotton (2.3 mm). The control group remained untreated. The glycerin-oxalic acid strips made of cellulose and cotton (2.3 mm) showed the highest efficacy, reducing the mite infestation by 17.79% compared to the control. The glycerin-oxalic acid strips of paper-cellulose (2.3 mm) were also effective, achieving a 17.05% reduction in mite levels. These results provide valuable insights for beekeepers seeking alternative and sustainable methods for controlling infestations.
Analysis of the axisymmetrical ionized gas boundary layer adjacent to porous contour of the body of revolution
The ionized gas flow in the boundary layer on bodies of revolution with porous contour is studied in this paper. The gas electroconductivity is assumed to be a function of the longitudinal coordinate x. The problem is solved using Saljnikov's version of the general similarity method. This paper is an extension of Saljnikov?s generalized solutions and their application to a particular case of magnetohydrodynamic (MHD) flow. Generalized boundary layer equations have been numerically solved in a four-parametric localized approximation and characteristics of some physical quantities in the boundary layer has been studied.