This paper discusses axially symmetric contact problems of rigid punch and poroelastic foundation interaction employing Cowin-Nunziato linear poroelasticity model. It is assumed that the punch base has a flat or parabolic shape, and the contact friction is neglected. Using Hankel's integral transform the considered contact problem is reduced to a solution of a singular integral equation with unknown contact stress. To solve this integral equation, the collocation technique is used. In the case of parabolic...

In Germany, the Dryopteris affinis complex has its main distribution in southern parts of the country, but also occurs in the Harz Mountains, the northernmost German low mountain range. From 2008 to 2018, the authors made a series of excursions into the Harz Mountains to study this group. To cor-rectly identify the taxa, samples were collected for flow cytometric analyses as well as micro- and macromorphological examinations. The following taxa and cytotypes were detected: D....

Депопулацията и стареенето на населението са основните фактори, които предопределят изменението на демографската ситуация в България през последните три десетилетия. Цел на настоящата разработка е да се изследва въздействието на синергията на тези негативни процеси върху развитието на страната посредством измененията в повъзрастовото разпределение на цялото население и населението в трудоспособна възраст за страната и по общини. Обект на изследването са взаимовръзките между средногодишните темпове на изменение на броя на населението на българските общини и...

The river streamflows analyses can be successfully used in water resource planning and management, depending on the needs of the wide range users. It is possible to use these applications in several general directions: as informal, qualitative guidance for water managers, stakeholders and decision makers and prediction about long-term drought variability; for quantitative assessments of longterm hydrologic variability and assessment the severity and duration of drought cycles; as direct inputs into hydrologic models of a...