Vjetrozaštitni pojasi uspostavljaju se kao barijere od redova stabala ili grmlja koje se sade s namjenom reduciranja brzine vjetra, smanjenja evapotranspiracije, zaštite od eolske erozije, ...istovremeno izravno se koriste za zaštitu kultura i nasada te osiguravaju povoljnije stanišne uvjete. Jedna od bitnih pretpostavki uspjeha podizanja pojasa je korištenje autohtonih vrsta drveća i grmlja prilagođenih na stanišne uvjete. Tehnologije i postupci zaštite mogu biti usmjerene na biološko-tehničke postupke pošumljivanja i podizanja nasada s ciljem ublažavanja udara vjetra. Izbor biljnih vrsta za podizanje nasada uvjetovan je različitim klimatskim zonama, biološko-ekološkim značajkama vrsta, ali i kompoziciji s ostalim elementima krajobraza. Zaštita od vjetra postavlja se prema pravcu udara glavnog vjetra. Uspostava vjetrozaštitnih pojasa ponajprije smanjuje snagu vjetra i reducira njegovu brzinu. Na taj način ublažavaju se klimatski ekstremi povezani s olujnim vjetrom (na kršu se ponajprije radi o buri) i utječe na mikroklimatske uvjete, što u konačnici može osigurati zaštitu poljoprivrednog i šumskog zemljišta.
Windbreaks are established as barriers of rows of trees or shrubs that are planted to reduce wind speed, reduce evapotranspiration, protect against aeolian erosion, while being used directly to protect crops and plantations and provide favorable habitat conditions. One of the essential preconditions for the success of belt raising is the use of indigenous species that are adapted to habitat conditions. Technologies and protection procedures can be focused on biological-technical procedures of afforestation and raising plantations with the aim of mitigating wind gusts. The goal of windbreaks and raising plantations with different species is shown in the following figures (Figures 3,4,5,6,7). The choice of plant species for raising plantations is conditioned by different climatic zones, biological and ecological characteristics of the species, but also the composition with other elements of the landscape. An important feature of windbreaks is their wind permeability and impact on wind speed. Permeability depends on the habitus of the plant, and the type of trees and shrubs. The density of the windbreak changes its impact and effectiveness; the permeable belt ensures a balanced distribution as part of the wind skips it and part passes through the belt. The wind protection is placed in the direction of the main wind. Technical wind protection procedures include the construction of barriers made of building materials such as brick, stone, timber, glass, hard plastic or a combination of several types of materials (Figures 1 and 2). Biological procedures in terms of species selection and consideration of habitat conditions are much more complex. All this in the context of frequent changes in the “wind structure” in the karst area. Belt lifting can be differentiated according to purpose and expected performance as follows: impermeable belt, semi-permeable and permeable belt. The establishment of windbreaks primarily reduces wind strength and reduces its speed. In this way, the climatic extremes associated with the stormy wind are alleviated (the karst is primarily a bora) and it affects the microclimatic conditions, which can ultimately ensure the protection of agricultural and forest land.
Bosna i Hercegovina ima pretežno brdsko-planinsku konfiguraciju terena, bogata je razvijenom hidrografskom mrežom. Pri projektiranju i izgradnji mreža šumskih cesta učestala je pojava presijecanja ...stalnih ili povremenih vodotoka pa je zato prijeko potrebno planirati i graditi vodopropusne objekte.Najrizičnija su mjesta, kada je u pitanju negativan utjecaj vodotoka na erozijske procese, upravo točke presijecanja šumske ceste rijekama i brdsko-planinskim vodotocima. Da bi se smanjio postotak neupotrebljivosti primarne mreže šumske transportne infrastrukture, treba pristupiti kvalitetnim rješenjima odvodnje površinskih voda i izgradnji prelazaka preko postojećih planinskih vodotoka. Vodna je erozija jedna od mogućih pojava, koja može nastati na kolničkoj konstrukciji, ako na odgovarajući način nije riješeno pitanje odvodnje površinskih i oborinskih voda.Procjena erozijskih procesa prilikom provođenja istraživanja utjecaja hidrografske mreže na primarnu mrežu šumske transportne infrastrukture obavlja se na osnovi terenskoga snimanja stanja vodopropusnih objekata i kolničke konstrukcije u njezinoj neposrednoj blizini.Prilikom istraživanja nisu analizirani tehnički elementi šumskih cesta (osim erodiranosti kolničke konstrukcije), aktivnosti su usmjerene na vodopropusne objekte, odnosno njihovo stanje i eventualni utjecaj na erodiranje kolničke konstrukcije. Istraživanja su provedena u GJ »Neretvica« u okviru ŠPP »Konjičko«.Analizirano je ukupno 129 različitih vodopropusnih objekata, od kojih su 16 mostova, 73 cijevna betonska propusta i 40 drugih tipova objekata. U okviru provedene analize vodopropusnih objekata obrađena je oštećenost i funkcionalnost vodopropusnih objekata te erodiranost kolničke konstrukcije u njezinoj neposrednoj blizini.
Water permeable structures on strip roads play a very important role in regulating the flow of surface water and rainwater. Although the
forestry operative of B&H does not use patterns that can be used to
correctly determine the dimensions of water-permeable structures, most often the selection of the dimensions of the structure that can ensure the smooth flow of water is done experientially.
Previous analyses show that investments in forest road infrastructure are insufficient (Sokolović and Bajrić 2011, 2013) and that this is the most common reason for the poor condition of forest road infrastructure. Erosion is a common occurrence on all unpaved roads, especially in heavy rain events and on steep slopes (Wang et al. 2021). Poor technical solutions, along with irregular maintenance of water-permeable structures, are a common cause of intensification of erosive processes and destruction of the road structure.
In the present study, a total of 129 water-permeable structures of various types were analyzed, of which 16 bridges, 73 concrete pipe culverts, and 40 ‘other’ types (improvised solutions of water-permeable structures, most often made of stone slabs). Bridges have the most efficient functionality, which allows water to flow freely through the flow profile. Also, concrete culverts of larger dimensions (Ø 80 and 100
cm) have better functionality than culverts of smaller dimensions (Ø 40
and 60 cm). Namely, in the case of specific small culverts, frequent partial blockages were observed, the maintenance of which was difficult due to the small dimensions of the culvert.
The worst functionality was observed with ‘other types’ of water-permeable structures, where collapses often occur, and as a result, they cannot be cleaned and have to be replaced instead. Of the total number of ‘other types’ of structures, 50% have difficult or disabled functionality, with 20% of the total number having disabled functionality. It is obvious that the choice of the type of water-permeable structures, as well as their dimensions, play a very important role when it comes to their future functionality.
Also, field research has determined the direct correlation between the functionality of water-permeable structures and the occurrence of erosive processes on the pavement structure in the immediate vicinity. That is, in the case of structures with impaired or disabled functionality, the water partially or completely overflows over
the pavement structure, whereby the surface rubs off the pavement and causes its erosion.
U ovome radu prikazani su rezultati analize realizacije poljozaštitnih šumskih pojaseva u postupku komasacije. Istraživanjem su obuhvaćena tri karakteristična projekta komasacije u Autonomnoj ...pokrajini Vojvodini, kroz čije provođenje je trebalo realizirati i projekte poljozaštitnih šumskih pojaseva. S obzirom da se izabrani projekti nalaze u različitim dijelovima područja istraživanja, zaključci izvedeni u ovome radu mogu se smatrati reprezentativnim za teritorij Vojvodine. Studija je pokazala da nije iskorištena prilika za povećanjem šumovitosti Vojvodine, odnosno da projekti poljozaštitnih šumskih pojaseva nisu uopće razmatrani u postupku komasacije ili ako su i uzimani u obzir, zemljište odvojeno za njih nikad nije privedeno namjeni.
The forests as a necessary condition for human civilization existence also are of great ecological and economic importance. This fact is often neglected in practice despite the fact on wide spread scientific knowledge about it. The authors noticed that practice and made research about shelterbelts realization in the numerous cases of theoretical researches as well as in projects of land consolidation projects in Serbia (mostly of them provided in Autonomous Province of Vojvodina as a region where agricultural land dominates). The benefits of shelterbelts are well known from scientific literature and practice for agricultural land protection, but the realization of them in concrete projects are connected with a lot of obstacles. In this paper more than the author ivestigated the projects of land consolidation from the aspect of the chances for building shelterbelts and their realization in practice. The research provided on more than eight hunderd projects of land consolidation has shown that only in a few of them the shelterbelts were forseen and no one of them was realized as designed. The reasons are mostly connected with the resistance of participants in land consolidation to give up of their land for shelterbelts building, with lack of capacities for seedlings providing and with the insufficient attention paid to this issue in legal regulation.
In this paper the results of analysis of shelterbelts in the process of land consolidation are shown. Research encompassed three different and distinguished projects of land consolidation in Autonomous Province of Vojvodina - The Republic of Serbia, through which realization was required to provide the projects of shelterbelts. Bearing in mind that chosen projects are spread in different geographical areas of research fields, the conclusions obtained in this paper could be considered as representative for Vojvodina. The Vojvodina is especcialy interesting for research because this region is lacking with forest. To reach the standards of 0.16 hecteares per citizen the woodlands in Vojvodina shall be increased from actual value of 193,621 hectares to the values of 308,045 hectares. Bearing in mind that importance of agricultural land and its preservation in the future from the aspect of sustainable development the land consolidation projects are the best chance for reaching before mention goal of increasing woodlands in Vojvodina. The study has shown that chance for increasing forest area in Vojvodina was not utilized, i.e. that projects of shelterbelts were not taken into consideration, and even if they were, the considered area was never brought to the designed goals. The visualization of project solutions and the actual implementation of the shelterbelts in the considered municipalities is shown in Figures 1-6. Overview of the number of analyzed projects of land consolidation, the number of land consolidation projects where was planned the establishment of shelterbelts and the number of land consolidation projects where are realized shelterbelts is given in Table 1.
Internal erosion is one of the most common failure mechanisms in hydraulic structures. The internal erosion is generally initiated by horizontal seepage in earth-filled embankments such as levees. ...With a newly developed apparatus we carried out a set of internal erosion experiments in horizontal seepage. The experiments used gap-graded granular soil to prepare the specimens. The experimental results revealed that, in a horizontal column, the upper part of the specimen is preferentially eroded, sequentially forming a dominant seepage area. When the erosion progresses, the dominant seepage area gradually expands from the upper part to the lower part of the column. At the particle scale, the localized fine-particle movement can be observed in the erosion process when the hydraulic gradient is relatively small, e.g., less than 0.62. During the early stage of erosion, the particles are rapidly eroded. With the erosion time increasing, the particle loss slows down and even ceases if there is sufficient time.
The atmospheric plasma spray process is one of the procedures used for the deposition of coatings resistant to wear due to friction, erosion, cavitation and corrosion. In this paper, the APS process ...produced a Cu10wt.%Al intermetallic coating which is a reliable candidate for use in tribological environments because of a combination of low price and exceptional resistance to abrasion under different work conditions. The aim of this study was to investigate the mechanical properties and the structure of the Cu10wt.%Al intermetallic coating and develop an efficient method for repairing and improving light alloy resistance to wear. Many components of copper alloys tend to be degraded due to corrosive environment, friction, erosion and cavitation. Such components can be saved by surface engineering with the use of appropriate coatings on surface areas exposed to degradation. A typical microstructure of a coating for the APS process is lamellar, with micro pores, unmelted particles, inter- lamellar oxides and precipitates present in it. The mechanical properties of Cu10wt.% Al coatings were investigated by measuring the microhardness of coating layers using the HV0.3 method while the bond strength was tested on a tensile machine. The morphologies of powder particles and the coating surfaces were analyzed on a scanning electron microscope (SEM). The analysis of the coating microstructure was carried out with the use of an optical microscope, and a share of micro pores was determined by analyzing the micrographs through an optical microscope (OM). / Плазменное напыление является одним из методов нанесения износостойких покрытий, устойчивых в т.ч. к истеранию, эрозии, кавитации и коррозии. В данной работе описан процесс создания интерметаллического покрытия Cu10вес.%Al, являющегося надежным кандидатом для применения в трибологических условиях эксплуатации. Преимуществом покрытия данного вида является сочетание низкой стоимости и повышенной стойкости к абразии в различных режимах эксплуатации. Цель данного исследования заключается в изучении механических свойств и структур интерметаллических покрытий Cu10вес.%Al и развитии эффективной методологии нанесения покрытия, а также в повышении износостойкости легких сплавов. Многие компоненты сплава меди в коррозийных условиях подвергаются кавитационному и эрозийному разрушению, но своевременная инженерия поверхности соответсвующим покрытием деградирующих слоев, поможет сохранить их. Типичная микроструктура покрытия напылением – ламеллярная, с микропорами, несплавленными частицами, межламеллярными оксидами и преципитатами. Испытания механических характеристик покрытия Cu10вес.%Al проводились методом HV0.3 а испытания прочности соединений − методом растяжения. Морфология частиц порошка и поверхности покрытия испытаны методом электронной микрографии (SEM) . Испытания микроструктуры покрытия проведены методом оптической микроскопии, а микропоры исследованы методом оптической микрографии ( ОМ). / Atmosferski plazma sprej je jedan od postupaka koji se koristi za depoziciju prevlaka otpornih na habanje usled trenja, erozije, kavitacije i korozije. U ovom radu, APS postupkom proizvedena je intermetalna prevlaka Cu10tež.%Al, koja je pouzdana za primenu u tribološkim okruženjima zbog kombinacije niske cene i izuzetne otpornosti na abraziju pri različitim uslovima rada. Cilj ovoga rada bio je da se izuče mehanička svojstva i struktura intermetalne prevlake Cu10tež.%Al i razvije efikasan metod za reparaciju i poboljšanje otpornosti lakih legura na habanje. Mnoge komponente od legure bakra imaju tendenciju da se degradiraju zbog korozivne sredine, trenja, erozije i kavitacije. Takve komponente mogu se spasti inženjerstvom površina sa primenom odgovarajućih prevlaka na površinama izloženim degradaciji. Tipična mikrostruktura prevlake za APS postupak je lamelarna u kojoj su prisutne mikropore, neistopljene čestice, međulamelarni oksidi i precipitati. Mehaničke karakteristike prevlake Cu10tež.%Al ispitane su merenjem mikrotvrdoće slojeva prevlake metodom HV0.3 i čvrstoće spoja metodom ispitivanja na zatezanje. Morfologija čestica praha i površina prevlake analizirana je na skening elektronskom mikroskopu (SEM). Analiza mikrostrukture prevlake urađena je uz korišćenje optičkog mikroskopa, a udeo mikropora određen je analizom mikrofotografija sa optičkog mikroskopa (OM).
The author proves the existence of four lakes on a Mercator's map from AD 1593. In thefirst part he explains the genesis of the map. The causes why the lakes disappeared and when it happened were ...adduced in the second part of the paper.
Vodogradbeni protipoplavni ukrepi predstavljajo pomemben del varstva pred poplavami. Z njimi lahko obvladujemo določen del poplavnega tveganja. Njihov osnovni namen je zmanjševanje poplavne ...nevarnosti na poplavnih območjih, ki si jih je prisvojil človek s svojimi najrazličnejšimi dejavnostmi. Predstavljeni so nekateri najpogostejši vodogradbeni ukrepi za varstvo pred škodljivim delovanjem hudourniških poplav, njihov osnovni princip delovanja, glavne prednosti in slabosti ter vplivi na okolje.
Recreational activity has a significant impact on the Priol’khonie steppes and forest steppes, which are part of the Pribaikalskyi National Park (western coast of Lake Baikal, Russia). The aim of ...this investigation is the assessment of different landscapes’ values for the provision of ecosystems functions and services. To meet these objectives, fieldwork was conducted in the Priol’khonie steppes and forest steppes during the summer of 2013. The function of phytomass formation was considered for different land-cover types identified in the area, and the above-ground phytomass and inter-rill erosion were measured. The level of landscape degradation was estimated and draft maps of phytomass stocks and vulnerability to soil erosion of the investigated area were compiled. To show the dependence between the studied ecosystem functions and the ecosystem services provided by them, a scoring of the latter was made. It was found that characteristics of ecosystem functions varied significantly in the steppes of the Priol’khonie.
Na stepe v Priolhonju in gozdne stepe, ki so del nacionalnega parka Pribajkalskij (zahodna obala Bajkalskega jezera, Rusija) imajo pomemben vpliv rekreacijske aktivnosti. Namen raziskave je ocena različnih vrednosti krajine za zagotavljanje ekosistemskih funkcij in uslug. Izvedli smo terenske raziskave v stepi Priolhonje in gozdnih stepah poleti leta 2013. Za različne krajine smo v raziskovanem območju ocenili funkcijo nastanka fitomase in izmerili nadzemno fitomaso in erozijo med jarki. Ocenili smo stopnjo degradacije krajine in naredili karto zaloge fitomase in ranljivosti zaradi erozije tal raziskovanega območja. Da bi prikazali odvisnost med obravnavanimi ekosistemskimi funkcijami in ekosistemskimi uslugami, ki jih le-te zagotavljajo, smo slednje ovrednotili. Ugotovili smo, da se značilnosti ekosistemskih funkcij v stepi v Priolhonju značilno razlikujejo
The purpose of the present research work was to observe the effects of drug solubility on their release kinetics of water soluble verpamil hydrochloride and insoluble aceclofenac from hydrophilic ...polymer based matrix formulations. Matrix formulations were prepared by the direct compression method. The formulations were evaluated for various physical parameters. Along with the dynamics of water uptake and erosion, SEM and in vitro drug release of the tablets were studied. Applying an exponential equation, it was found that the kinetics of soluble drug release followed anomalous non-Fickian diffusion transport whereas insoluble drug showed zero-order release. SEM study showed pore formation on the tablet surface that differed depending on drug solubility. t-Test pointed to a significant difference in amount of both drugs released due to the difference in solubility. Solubility of the drug effects kinetics and the mechanism of drug release.
Cilj rada bio je praćenje učinka topljivosti na kinetiku oslobađdanja vodotopljivog verapamil hidroklorida i netopljivog lijeka aceklofenaka iz matriksnih sustava na bazi hidrofilnog polimera. Matriksni sustavi pripravljeni su izravnom metodom kompresije. Uz ispitivanje uobičajenih fizikalnih svojstava, ispitivana je i dinamika primanja vode, te erozija, SEM i in vitro oslobađanje ljekovite tvari iz tableta. Primjenom eksponencijalne jednadžbe utvrđeno je da mehanizam oslobađanja topljivih lijekova slijedi anomalni ne-Fickov difuzijski transport, dok netopljivi lijekovi slijede kinetiku nultog reda. SEM ispitivanja pokazala su pore na površini matriksa ovisne o topljivosti ljekovite tvari. t-test ukazuje da količina oslobođenog lijeka značajno ovisi o njegovoj topljivosti. Topljivost lijeka ima značajan učinak na kinetiku i mehanizam oslobađanja.
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