Long term changes and recent state of macrozoobenthic communities along the Bulgarian Black Sea coast

The analysis of macrozoobenthic samples collected from 34 stations along the Bulgarian Black Sea shelf at depths ranging from 12 to 83 m yielded 103 taxonomic units. The average abundance established in the present study was over 5000 ind/m2 with nearly 70% dominance of the polychaetes. The number of species, Shannon-Wiener diversity index (H') and Pielou's evenness (J) were the lowest in Varna and Burgas bays, indicating that they are the most ecologically threatened areas along the Bulgarian Black Sea coast. The quantitative and qualitative data were compared to published data from the pristine period 1954-1957 and from the period 1982-1985 with intensive anthropogenic pressure. The comparison revealed an increase of the share of molluscan species and a decrease of the contribution of crustacean species in the total number of species. A 7-fold increase of the total average abundance was established compared to the pristine period 1954-1957. During the recent period the polychaetes are the most dominant group in the benthic abundance, while during the pristine period 1954-1957 the most abundant were the molluscs with nearly 61% of the total abundance. These changes in the benthic communities are attributed to the process of eutrophication. While in the pelagic environment signs of recovery have been observed, we deem that up to 1997 no such signs are valid for the benthic communities

Coastal benthic diversity in the Black and Aegean Seas

Quantitative data pertaining to the composition of macrobenthic communities of soft bottoms along the coastal zones of the Black and Aegean Seas are reviewed. The study area includes one site in the Russian coastal zone, four sites in Ukraine (at depths 3-125 m), four sites in Bulgaria (at depths 12-83 m), and four sites in Greece (at depths 9-90 m). The species variety, population density and community diversity are compared between Seas, among regions and among stations. The fluctuation of these parameters in connection to anthropogenic impact (ranging from open undisturbed sites to those receiving heavy organic and chemical effluent) are discussed. The low species number of benthic fauna in the Black Sea, as opposed to the richness of the Aegean Sea (three times higher) a ratio well established for other marine groups, is not reflected in the overall abundance. Thus, the average population density of benthic organisms may reach 12352 ind per m2 in the Black Sea (Cocketrice sandy bank) while in the Aegean it did not exceed 4,000 ind per m2 (Saronikos Gulf). Community diversity was always lower in the Black Sea than similar sites in the Aegean Sea. Within the various regions examined, the protected areas exhibited the most complex community structure

Обработка на данни от сложни обекти чрез методи за разпознаване на образи

 In the description of complex objects, we need methods which could reflect the complex interconnections between components and sift out if possible those of them which are substantial for the specific application. It is offered in this publication the pattern recognition methods should be used as a unified method for processing of data from complex objects. The proposed algorithm may be used in the recognition of the condition of objects of various nature. The indicated examples prove the practical applicability of the methodology as they represent the solution of specific practical problems

Optimizing Weight of Housing Elements of Two-stage Reducer by Using the Topology Management Optimization Capabilities Integrated in SOLIDWORKS: A Case Study

This paper presents the results of a conducted topology management optimization study based on the finite element analysis on a two-stage spur gear reducer housing body and cover using the SOLIDWORKS Simulation module. The main goal of the study is to optimize the overall weight of the reducer by thinning specific areas of the casted gearbox housing elements according to the calculated minimal strain energy. The topology optimization algorithm that is used in current research gives an optimal structural shape of the housing elements of the reducer with the largest stiffness, considering the given amount of mass that will be removed from the initial design space. The complete sequence of steps for conducting the topology management optimization study is shown, taking into account the constraints arising from the construction features and the method of manufacturing the housing elements of the gear reducer. Conclusions on the use of the topology optimization results are given and potential directions for further development of the approach are also identified

An algorithm for topology optimization of gear reducer housing elements

In recent years, topology optimization methods are becoming more widely used in many engineering fields, and they are already being successfully integrated at the design stage of the different types of products. An active field of research in this area is the definition of appropriate constraints in topology optimization models in order to facilitate the production of the optimized objects. An algorithm for topology optimization of housing elements from gear reducers by using the capabilities of CAD-CAE topology optimization software is presented in the current work. The purposed algorithm is taking into account the resulting loads during operation of the reducer, the geometrical and manufacturing constraints of the production process of these housing elements. Obtained results from conducted Taguchi experimental study to investigate the impact of some topology optimization control parameters over optimized 3D-model also are shown and discussed. Conclusions on the applicability of the algorithm have been made

Winter wheat varieties responsiveness to soil and foliar fertilization

Common winter wheat (Triticum aestivum L.) makes up more than half of the cereals grown in the European Union and in Bulgaria. For two years (2021-2022) a field experiment was carried out at the experimental plain of the Department of Plant Production at the Technical University of Varna. Two varieties of winter common wheat were grown, a selection of the Dobrudja Agricultural Institute - General Toshevo. The trial pattern included a variant without fertilization (control - Fert 0), a variant with combined foliar feeding and soil fertilization (Fert SF) and a variant with soil fertilization alone (Fert S). The effect of the way of fertilizing on the productivity and quality of winter common wheat was investigated. Grain yield (GY) and its structural elements - spike length (LMS), number of grains per spike (NGS) and grain weight per spike (WGS), weight per 1000 grains (TGW) and hectoliter weight (TestW) were determined. Biochemical analysis of the wheat grain was performed and the content of protein (Pr), starch (St) and ash substances (Ash) was determined. Fertilization has a strong effect on productivity and grain quality in winter common wheat (both alone and in combination with growing conditions). The method of fertilization has an effect on the productivity of winter common wheat - feeding with foliar fertilizers during the spring vegetation (in the tillering and booting phases) increases grain yield as a result of increasing each of the productivity components. The method of fertilization does not have a significant impact on the quality indicators of winter common wheat, with the exception of the hectoliter mass, whose values are proven to be higher during soil nutrition. The two studied Bulgarian varieties, Sladuna and Nikodim, differ from each other in their efficiency in relation to the way of feeding in the spring

Diagnosis and treatment of liver abscesses

Pyogenic abscesses are rare and difficult problem for modern surgery because of the high mortality rate. After the 70s of the last century the introduction of new image methods as ultrasound diagnostics, percutaneous and direct cholangiography and biliary drainage, guided aspiration, and percutaneous drainage of the abscess cavity dramatically changed both the diagnosis and treatment of these patients. The routine diagnostic methods are ultrasound and CT scan. Percutaneous aspiration and drainage under ultrasound or CT control is applied as first-line treatment of hepatic abscesses.Scripta Scientifica Medica 2008; 40(2): 137-139