Notranji in zunanji transportni upor v procesu nestacionarne adsorbcije vlage v les

The assumption that non-stationary sorption processes associated with wood canbe evaluated by analysis of their transient system response to the disturbance developed is undoubtedly correct. In general it is, in fact, possible to obtain by time analysis of the transient phenomenon - involving the transition into an arbitrary new state of equilibrium - all data required for a credible evaluation of the observed system. Evaluation of moisture movement during drying or moistening requires determination of external moisture transfer resistance from or to wood surfaces, as well as internal resistance. Time-dependent changes in the moisture content of the spruce (Picea abies Karst.) samples of different thickness were monitored gravimetrically, during which the frequency of weighing was in accord with thespeed of moistening. It was assumed that quasi-isothermal sorption processes associated with wood could be evaluated as first order systems. The characteristic time constant ? determines, wholly and uniformly, the time dependence of the sorption process for the relevant sorption range of wood tissue. The connection between the time constant and the thickness of the sample measured in the direction of the material flux is potential, with the power depending solely on the relationship between the external mass transfer convection and internal diffusion resistance. To determine the said resistances or coefficients of mass transfer convection and diffusivity, the experiment must be carried out on samples of varying thickness. It is only in this way that the external mass transfer convection and internal diffusion resistance can be correctly distinguished.Predpostavka, da je možno nestacionarne sorptivne procese, povezane z lesom, ovrednotiti z analizo njihovega časovnega prehodnega sistemskega odziva na nastalo motnjo, je nedvomno pravilna. V splošnem je namreč s časovno analizo prehodnega pojava, gre za prehod v poljubno novo ravnovesno stanje, možno pridobiti vse potrebne podatke za verodostojno vrednotenje opazovanega sistema. Vsak prehod v novo ravnovesno stanje je ne glede na lastnosti opazovanega sistema nestacionaren in kot tak primeren za analizo nestacionarnih pojavov, kot so na primer sorptivni procesi, povezani z lesom. Za analizo sorpcijskih transportnih značilnosti je treba poznati tako notranjidifuzijski kakor tudi zunanji masni prestopni upor. Časovno odvisne spremembe vlažnosti v smrekovih vzorcih (Picea abies Karst.) različnih debelinsmo spremljali gravimetrično, pri čemer je bila pogostnost tehtanja skladna hitrosti navlaževanja, se pravi v začetku največja, z naraščajočo masovzorcev pa se je zmanjševala. Predpostavljeno je bilo, da lahko sorbcijskeprocese, povezane z lesom, vrednotimo kot sisteme prvega reda. Značilna časovna konstanta ? določa časovno odvisnost sorbcijskega procesa za relevantno sorptivno območje lesnega tkiva v celoti in enolično. Zveza med časovno konstanto in debelino vzorca, merjeno v smeri snovnega toka, je potenčna, pri čemer je vrednost potence odvisna zgolj od razmerja med zunanjimprestopnostnim in notranjim difuzijskim uporom. Za določitev omenjenihuporov oziroma koeficientov snovne prestopnosti in difuzivnosti je treba napraviti eksperiment na vzorcih različnih debelin. Samo tako je mogoče korektno ločiti zunanji prestopnostni in notranji difuzijski upor

Oak forests of Croatia

Hrastovi predstavljaju važnu komponentu šumske vegetacije u Hrvatskoj. Različite vrste hrastova dolaze u različitim vegetacijskim zajednicama diljem zemlje. Osim ekološke važnosti, bitni su i u industriji kao drvni materijal. Ovaj rad donosi pregled najvažnijih fitocenoza Hrvatske koje uključuju hrastove kao bitnu komponentu. Nakon kratkog osvrta na hrastove kao rod slijedi pregled po klimazonalnim zajednicama.The oaks represent an important component of forest vegetation of Croatia. Different oak species form a variety of phytocoenosis all over the country. Except for their ecological value, they're industrially important as wood material. This paper brings an overview of most important oak phytocoenosis in Croatia. A short review of oak species growing in Croatia is followed by an overview of its plant communities through climatic zones

Stairway to Excellence. Country Report: Slovenia

In the frame of the Stairway to Excellence project, complex country analysis was performed for the EU MS that joined the EU since 2004, with the objective to assess and corroborate all the qualitative and quantitative data in drawing national/regional FP7 participation patterns, understand the push–pull factors for FP7/H2020 participation and the factors affecting the capacity to absorb cohesion policy funds. This report articulates analysis on selected aspects and country-tailored policy suggestions aiming to tackle the weaknesses identified in the analysis. The report complements the complex qualitative/ quantitative analysis performed by the IPTS/KfG/S2E team. In order to avoid duplication and cover all the elements required for a sound analysis, the report builds on analytical framework developed by IPTS.JRC.J.2-Knowledge for Growt

Structural Violence and Migration: Explaining Global and Local Total Institutions

Decades ago Johan Galtung presented his perspective on violence which includes the distinction between structural, direct and cultural violence. This paper tries to incorporate his approach and present the connection between structural violence and migrations with focus on immigration in the EU. The author argues that the consequence of structural violence is the appearance of two types of excluded spaces: a) global total institutions, which include countries or entire regions of economically less or underdeveloped countries; b) local total institutions within the economically developed countries, which include physical spaces (immigrant neighbourhoods, ghettos, prisons, detention centers for foreigners, etc.) and also social spaces of exclusion in which immigrants are put due to stereotype, prejudice and consequential discrimination.要旨数十年前、ヨハン・ガルトゥングは構造的、直接的、文化的な暴力の違いを含む暴力についての見解を示した。本稿ではその視角を取り入れながら、ＥＵ内の移民政策に焦点を当て構造的暴力と移住の関係について述べたい。構造的暴力とは、以下の２つのタイプの排除された空間の出現であると考えられる。a) 経済的に遅れている国や発展途上国などを含むグローバルな空間の出現。b) 物理的な空間を含む経済先進国内の地域空間（移民地域、ゲットー、刑務所、外国人拘留センターなど）や固定観念による先入観や差別を受け移民が排除される社会的空間の出現

Razglednice iz Japana pripadnika austrougarske mornarice

Many of the old Japanese postcards archived in Slovenia today date from the period between the 1890s and 1920s when Austro-Hungarian Navy members were active and travelled to Japan as a part of their duties. Collectors and users of these postcards were of Slovenian origin. Their postcards were identified in the National and University Library in Ljubljana and in the Maritime Museum “Sergej Mašera” Piran. A postcard in private possession has also been added to the list. The format regulation of postcard printing changed in Japan in 1907 and this is confirmed using the postcards identified in Slovenia. The main motifs of the pictures were of scenery, portraits and individual objects. Among them, the category of scenery is dominated by ports, such as Yokohama, Kobe and Nagasaki, which are later overtaken as they become tourist destinations. The most characteristic postcards from this period around the turn of the century fall under the category of portrait: clothing and hairdos, customs and professions were all the focus of attention. These photos were made in photo studios with the aim of introducing Japan and its culture to Western visitors. As for the category of individual objects, picture postcards of Russian and Japanese warships attract our eyes.Mnoge stare japanske razglednice arhivirane u današnjoj Republici Sloveniji su iz razdoblja između 90-ih godina 19. i 20-ih godina 20. stoljeća, kada su pripadnici austrougarske mornarice bili aktivni i kao dio svojih dužnosti putovali u Japan. Kolekcionari i korisnici ovih razglednica bili su slovenskoga podrijetla. Njihove se razglednice čuvaju u Nacionalnoj Sveučilišnoj knjižnici u Ljubljani i u Pomorskome muzeju “Sergej Mašera” Piran. Na popisu se također nalaze i razglednice u privatnome vlasništvu. U Japanu se regulacija formata tiskanja razglednica promijenila 1907. godine, što potvrđuju i razglednice u Sloveniji. Glavni motivi slika bili su krajolik, portret i pojedinačni objekt. Među njima, u kategoriji krajolika dominiraju luke, kao što su Yokohama, Kobe i Nagasaki, koje kasnije bivaju zamijenjene turističkim destinacijama. Najkarakterističnija za ovo razdoblje na prijelazu stoljeća je kategorija portreta, u čijem su središtu pozornosti bili odjeća i frizure te običaji i zanimanja. Te fotografije snimljene su u fotostudijima da bi predstavile Japan i njegovu kulturu Zapadnim posjetiteljima. Što se tiče kategorije pojedinačnih objekata našu pozornost najviše privlače razglednice sa slikama ruskih i japanskih ratnih brodova

What Does the (In)ability to React to the Covid-19 Coronavirus Reveal About Our Societies?

The many questions raised by the novel coronavirus pandemic go far beyond medical issues. Everything that was self-evident recently became impossible after the global spread of the virus. Despite the declarative EU emphasis of solidarity, the novel coronavirus pandemic clearly demonstrated the limits of solidarity and opened doors to nationalism. This crisis reveals all the anomalies of globalisation and the capitalist system in its currently dominant version of neoliberalism. The present crisis is indeed posing a serious challenge to the existing state system and capitalist economy. Evidence in support of this argument may be found in the surprising generosity of governments in many countries. Former enthusiastic advocates of austerity measures have come to realise that the legitimacy of the system is being tested at this time

Resonance in idling circular saw blades

V članku je prikazana analiza aerodinamičnega vzbujanja prosto vrtečega se krožnega žagnega lista. Ko se krožni žagni list prosto vrti, se zrak v pazdušnem prostoru ozobljenega dela orodja pri prehodu rezila loči od njegovihmejnih bočnih površin in tvori spremenljivo valovito brazdo oziroma turbolentni tok zraka. Posledica časovno spremenljivega turbolentnega toka je nastanek spremenljivega tlaka zraka ob površnah rezila, kar predstavlja aerodinamično vzbujanje žagnega lista. Za pojav prečnega resonančnega nihanja orodja ne zadošča zgolj aerodinamično generirana vzbujevalna sila s primerno frekvenco. Poleg omenjenega pogoja morata biti namreč izpolnjena še dodatna pogoja, in sicer morajo biti vzbujevalne tlačne razlike okoliškega zraka primerno velike, dušilne sposobnosti materiala nosilnega telesa žagnega lista pa dovolj majhne. Ugotovili smo, da nikoli nista vzbujena dva ali več lastnih načinov nihanja hkrati in da je prehod iz enega resonančnega stanja v drugega skokovit. Z naraščajočo frekvenco vrtenja se praviloma povečuje tudi območje vrtljajev, v katerem pride do aerodinamične vzbuditve lastnih nihajnih načinov.The article deals with the analysis of the aerodynamic excitation of a freely rotating circular saw blade. When the circular saw blade rotates freely, the air in the gullet spaces of the rim area of the tool separates (in the passing of the knife from its border flanking surfaces) and forms a variable waveform wake or turbulent airflow. The consequence of the time-variable turbulent airflow is the occurrence of variable air pressure along the knife surfaces, which constitutes the aerodynamic excitation of the saw blade. For the occurrence of transversal resonant vibration of the tool, there does not suffice only aerodynamically generated excitation force at a suitable frequency. In addition to the said condition, two additional conditions must also be met: the exciting pressure differences of the surrounding air must be adequately large, and the damping capabilities of the material of the saw plate sufficiently small. We have found that two or more natural manners of vibration are never excited simultaneously and that the transition from one resonant condition into another is abrupt. With the increasing frequency of rotation there is also, as a rule, an increase in the range of rotations in which the aerodynamic excitation of natural manners of vibration occurs

Oblique cutting as a method for determination of the fractural properties of oriented wood tissue

Prikazana je metoda določevanja kritične koncentracije napetosti na podlagi dolžine segmenta odrezka tipa I, nastalega v procesu premočrtnega ortogonalnega odrezavanja bukovine (Fagus silvatica) v smeri 90°-0°. Eksperimentalni rezi so bili narejeni na 10 mm debelih vzorcih pri cepilnem kotu 31° in 42°, debelina odrezka pa se je spreminjala v območju med 0,1 in 0,3 mm. Z metodo končnih elementov smo modelirali reprezentativni segment odrezka različnih dolžin in debelin. Spreminjali smo obremenitev segmenta ter vsakič izračunali koncentracijo napetosti na konici razpoke ter tlačno napetost v hipotetičnem odrezku. Ob predpostavki, da se razpoka pri ločevanju tkiva širi zgolj v primeru, ko je koncentracija napetosti v njenem korenu kritična, ter da se tlačne napetosti v nastajajočem odrezku nenehno povečujejo vse do mejne vrednosti, lahko na osnovi znane dolžine reprezentativnega segmenta odrezka in tlačne trdnosti vzdolž poteka tkiva izračunamo kritično koncentracijo napetosti oziroma določimo lomno togost aktualnega materiala. Razpoka napreduje namreč vse dokler tlačna napetost ne doseže porušne vrednosti, kar se zgodi na mestu loma odrezka. Kritične koncentracije napetosti, ki smo jih določili na osnovi dolžine reprezentativnega segmenta odrezka debeline 0,3 mm, se zelo dobro ujemajo z vrednostmi, dobljenimi s klasičnim frakturnim testom. Pri manjših debelinah odrezka prihaja do manjših odklonov, kar je najverjetneje posledica povečane asimetrije vzorca. Prikazano metodo lahko nedvomno označimo kot učinkovito in verodostojno, kar je tudi najbolj pomembno. Metoda je zelo enostavno in hitra, kajti lomne lastnosti aktualnega materiala je praktično moč določiti že z enim samim premočrtnim rezom. Treba je tudi poudariti, da je priprava vzorčnega materiala nezahtevna, kajti edino, na kar moramo paziti, je usmerjenost tkiva.The method for determination of critical stress intensity factor based on chip segment length of chip type-I originating from orthogonal oblique cutting of beech wood (Fagus silvatica) in the 90°-0° direction is shown. Experimentalcuts on 10 mm thick specimen with rake angles 31° and 42° were made, and the chip thickness varied between 0,1 mm and 0,3 mm. Using the finite element method, we modelled a representative chip segment of varying length and thicknesses. We varied the load at the chip segment and calculated,for each case, stress intensity at the crack tip and compressive stress in hypothetical chip. On presumption that the crack propagates during tissue separation only when the stress intensity at the crack tip equals the critical stress intensity and the compressive stress rises in chip formation process up to the limit strength, we can calculate the critical stress intensity factor by knowing the chip segment length and compressive strength in longitudinal direction. Specifically, the crack propagates until the compressive stress reaches the strength, which occurs at the place of chip break. Critical stress intensity factor calculated from representative 0.3 mm thick chip segment length agrees well with values obtained with classical fracture tests. The results obtained from thinner chip segments deviates to a lesser extent, which is most probably a consequence of highly unsymmetrical specimen. The method has been undoubtedly shown as effective and reliable, which is the most important. The method is very simple and fast, enabling us to determine the fracture properties practically with a single oblique cut. It has to be emphasized, that the specimen preparation is also undemanding, for the only thing we have to pay attention to is the tissue orientation