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We continue our research in the enumeration of Hamiltonian cycles (HCs) on thin cylinder grid graphs Cm × Pn+1 by studying a triangular variant of the problem. There are two types of HCs, distinguished by whether they wrap around the cylinder. Using two characterizations of these HCs, we prove that, for fixed m, the number of HCs of both types satisfy some linear recurrence relations. For small m, computational results reveal that the two numbers are asymptotically the same. We conjecture that this is true for all m ≥ 2.

The article deals with the morphogenesis of the through cave Pećina na Reci Zamni (meaning in Serbian: Cave on the Zamna River; in further text: the Zamna Cave). The Zamna Cave was the subject of several geomorphological studies, mostly aimed at explaining the cave genesis through the evolutionary concept from through caves to natural bridges. In order to get better insight into the morphogenesis of this cave, modern geomorphometrical methods were applied. The cave and the surface topography above it were scanned in high resolution using the instrument Leica Nova MS50, applying the method of terrestrial laser scanning (TLS). Data processing produced the model for the analysis of the relation between surface and underground forms of karst relief. The results point to the conclusion that the Zamna Cave is an example showing that in the process of natural bridges formation by cave roof collapse, it is not necessary that there is a dry valley above the cave, as previously thought.

Solving traffic problems, rather than in a conventional manner, i.e. through the construction of infrastructure and customization requirements, began to be implemented in a different way, by applying measures to motivate users to -use passenger car less, and that more of their daily activities are reached by nonmotorized modes of movement. Sustainable urban transport plans (SUP) were introduced in legislation of the EU, strategic documents that help create a better quality of life in cities. For the purposes of this study, a review of the literature related to existing plans of some major European cities was carried out, as well as small, focusing on cities of the surroundings. On this basis, the similarities and differences were ephasized in proposed measures to reach the goals of sustainable development of transportation systems. In conclusion recommendations are given on the possibility of use of experiences and applications in all the individual local communities.

The impregnation of differently prepared chitosan gels with thymol using supercritical carbon dioxide (scCO2) was studied in order to obtain new materials with added value without the use of organic solvents. The optimum conditions of supercritical impregnation (15 MPa, 35 °C and 24 h) were defined based on previously investigated thymol solubility in scCO2. Cross-linkers formaldehyde and glutardialdehyde were used to prepare chitosan hydrogels. The obtained hydrogels of chitosan were converted in acetogels and then dried with air or by using scCO2 in order to obtain xerogels and aerogels. The best results, in terms of morphology and yield of impregnation with thymol, have been achieved for the aerogel of chitosan (11.30%) which was obtained with cross-linker formaldehyde and dried with scCO2 at 15 MPa and 50 °C.

Mountains are usually understood as high elevation areas, which are sparsely populated and where nature is preserved. The elevation above sea level is the most commonly taken as a criterion for mountain delineation, but the complexity of the task arises when definitions are compared in different national contexts, between projects and particularly when they are applied in decision-making process. Therefore, this paper aims to give a review of the existing palette of mountain definitions and mountain area delineations, to recognize some common criteria used in the definitions, as well as to review topics and situations in which the delineations are applied and used in spatial planning. Due to the diversity of cases, it was necessary to reduce scope of the topic; therefore the paper is limited to the European context and particularly to countries representing the largest European mountain massifs - Alps, Apennines, Pyrenees, Dinaric Alps and Carpathians.

Size effect of the subharmonic Shapiro steps on the behavior of harmonic ones is studied in the ac driven overdamped Frenkel-Kontorova model with different types of physically important realistic substrate potentials. The properties of harmonic Shapiro steps are directly correlated with the size of halfinteger steps; and according to that in their amplitude dependence, three distinctive types of behavior have been classified. Our results on other realistic systems show that these classifications are not universal, and that not only the size of halfinteger steps but also the type of the substrate potential determines the properties and correlation between the Shapiro steps. While for some potentials such as variable and double-barrier potential, system evolves through different types of amplitude dependence as the size of halfinteger steps changes, in the case of double-well potential, the system maintains the standard behavior (the behavior for small halfinteger steps) even in the presence of large halfinteger steps. [ABSTRACT FROM AUTHOR]