Postcatastrophic Relicts and Relics: the Fate of Images after the Holocaust (on the Basis of Works by Dina Gottliebová-Babbitt and Christian Boltanski)

The text concerns itself with the afterlife of visual representations of the victims of the Holocaust. With regard to Classe terminale du lycée chases en 1931: Castelgasse, Vienne by the French artist Christian Boltanski and drawings made by Dina Gottliebová-Babbitt in Auschwitz, questions of ownership and the appropriation are discussed. The article addresses the aporias of postcatastrophic attitudes towards the remnants of the Holocaust as well as the way in which they are treated and dealt with. The paper states, that the dynamics of dispossession, appropriation and re-appropriation that have been set into motion by the Holocaust, have not come to an end nor will they come to an end in the foreseeable future

Akustična svojstva drvnih i nedrvnih materijala za izradu kućišta klavira

This article presents the possibilities of substituting expensive and scarce wood materials in the construction of piano cases, especially the front panels of upright pianos. Three-layer blockboard, multi-layer plywood, medium-density fibreboard (MDF), and Purenit were selected for the study. These materials were long-time climatised at 20 °C and 50 % relative air humidity. Their frequencies, damping coefficient and relative amplitude were measured. The density r, sound velocity v, dynamic modulus of elasticity E´, sound impedance Zn, and Acoustic Conversion Efficiency (ACE) were calculated. With the materials used to make the front panels of an upright piano, a subjective assessment of the instrument’s acoustic response was made. The presence of front panels of any type was found to have a negative effect on the sound except at low frequencies. With panels fitted, the best acoustic properties were achieved by blockboard, followed by plywood, MDF and Purenit panels in that order; this was affirmed by the subjective assessment. The best acoustic performance was achieved by blockboard and plywood. Taking both price and performance into consideration, MDF presented the best compromise. Purenit was ruled out due to its high damping properties.U ovom su članku prikazane mogućnosti zamjene skupih i rijetkih drvenih materijala za izradu kućišta klavira, posebice prednjih ploča uspravnih klavira. Za istraživanje su odabrane stolarska ploča, furnirska ploča, srednje gusta ploča vlaknatica (MDF) i purenit ploča. Ti su materijali dugotrajno klimatizirani pri temperaturi 20 °C i 50 %-tnoj relativnoj vlažnosti zraka. Mjerene su njihove frekvencije, koeficijent prigušenja i relativna amplituda. Izračunane su gustoća r, brzina zvuka v, dinamički modul elastičnosti E´, zvučna impedancija Zn i učinkovitost akustične pretvorbe (ACE). Napravljena je subjektivna procjena akustičkog odziva instrumenta za materijale upotrijebljene za izradu prednjih ploča uspravnog klavira. Utvrđeno je da prednje ploče uspravnih klavira izrađene od bilo koje vrste odabranih ploča imaju negativan utjecaj na zvuk, osim na niskim frekvencijama. Prema subjektivnoj procjeni, najbolja akustična svojstva pokazala je stolarska ploča, zatim furnirska ploča te MDF i purenit ploča. Najbolja akustična svojstva imaju stolarska i furnirska ploča. Uzimajući u obzir cijenu i performanse, MDF je najbolji kompromis. Purenit je isključen zbog jakog prigušivanja zvuka

Effects of species and moisture content on the behaviour of solid wood under impact

The article's main aim is to assess the effects of species and moisture content (MC) on the behaviour of solid wood material under the low velocity of impact and present a pattern for predicting loading vs time curves for these species in different moisture levels. Three groups of samples (300 x 20 x 20 mm) were made from beech, oak, and spruce wood. Each group was subdivided into two groups with low moisture content (LMC) level (10-12%) and high moisture content (HMC) level (40-60%). A drop-weight impact machine did the tests, and high-speed cameras recorded the lateral specimens' surface during the impact. The digital image correlation technique (DIC) determined the strain pattern and the deflection. The timing of the crack initiation was also observed. Also, the force-time charts, the maximum force required for crack initiation, the work needed for crack initiation, and the total work required for the breakage of every specimen were gathered. A general force-time pattern with five identifiable steps was determined for each group. It turned out that the maximum deflection and longitudinal tensile strain of the beams up to crack initiation increase with increased moisture content while maximum force decreases. Unlike beech, the required work for rupture of HMC samples of oak and spruce is higher than LMC group.OA-hybri

Incipient decay in beech (Fagus sylvatica L.) and linden (Tilia cordata Mill.): An interspecific static and dynamic material analysis

With increasing awareness of the ecological value of trees in urban areas, there is a growing need to preserve mature specimens often colonised by wood-decay fungi. Nonetheless, cases of stem collapse or uprooting of such trees under adverse weather conditions remain a significant issue requiring further investigation. Depending on the decay type and the wood structure of the host tree, different combinations of wood-decaying fungi and host species can have varying impacts on the mechanical and vibroacoustic properties of green wood. This study compares the physical and mechanical properties of green European beech (Fagus sylvatica L.) and small-leaved linden (Tilia cordata Mill.) artificially exposed to Fomes fomentarius (L.) Fr. and Kretzschmaria deusta (Hoff.) P.M.D. Martin after different exposure periods. Mass loss () caused by both fungi differed according to the wood species. A statistically significant difference between the two fungal species was observed in beech wood, but not in linden. Significant differences in the modulus of rupture () and dynamic bending modulus of elasticity () were observed among the fungus-wood combinations, also depending on the exposure time. The relationships between and varied according to the fungal species, where at the same values, K. deusta caused a higher loss in both wood species. Strong relationships between and were demonstrated for all fungus-wood combinations, without significant differences related to the decay type. The is a reliable parameter for predicting loss even at incipient degradation stages, irrespective of the type of decay. The presented results can lead to better prediction of the impact of fungal colonization on standing trees and improve non-destructive methods used for tree stability assessment.OA-hybri

Elasto-plastic material model of oak at two moisture content levels

The mechanical properties of wood show a very high dependence on the moisture content (MC). A consideration of MC in numerical simulations increases the applicability of such prediction with respect to application and moisture states of the wood material. The goal of this work is to develop an accurate orthotropic elasto-plastic model for oak wood (Quercus robur L.) at two different MC levels applicable for finite element analysis (FEA). To achieve this goal, the following steps were carried out: (a) in-house standard specimens tests in compression, tension, and shear and in all three orthogonal directions, followed by three-point bending, where all specimens were conditioned to a 12 and 25.6% MC, prior to the mechanical test; (b) integration of all obtained material characteristics into the consistent numerical material models; (c) validation of the developed material models by comparing the numerically predicted values with the experimental ones; and (d) iterative calibration of the material models by adjusting the individual material characteristics to minimize error using a reference. Material models were successfully developed with the following mean relative errors: 5.2% for 12% MC and 5.8% for 25.6% MC, respectively. Both numerical material models consistently predicted the oak elasto-plastic response that can be easily integrated into any FEA.OA-hybri