Predviđanje optimalne gustoće ekspandiranog polistirena za najbolje performanse toplinske izolacije polistirenske kompozitne iverice primjenom umjetne neuronske mreže

The objective of this study is to predict the optimum expanded polystyrene (EPS) densities for the best insulation properties of the particleboards manufactured with waste EPS instead of formaldehyde-based adhesives used in particleboard production with artificial neural network (ANN). For this purpose, the waste EPS particles of five different densities were used in the production of composite particleboards. The experimental dana used in the study were obtained from the previous study. Half of the beech, poplar, alder, pine and spruce chips were dried in a drying oven and the other half were naturally conditioned at room temperature, and then 18 mm thick three-layer composite particleboards were produced. The thermal conductivity of panels was determined according to ASTM C 518. The prediction model with the best performance and acceptable deviations was determined by using statistical and graphical comparisons between the experimental data and the prediction values obtained as a result of ANN analysis. Then, using this prediction model, the thermal conductivity coefficient values were estimated for the intermediate EPS densities that were not experimentally tested. According to the analysis findings, the thermal insulation performance for both beech and spruce polystyrene composite particleboards (PCP) panels increased with using of waste EPS foams with a density of 30 kg/m3. The lowest thermal conductivity values were obtained from the EPS waste foams with the density of 18, 13 and 22 kg/m3 for the PCP panels produced with poplar, alder and pine in the natural drying, respectively. In the technical drying, these values were found to be 15, 14 and 11-13 kg/m3, respectively. Technical drying showed much better thermal performance than natural drying while poplar indicated the best performance among the wood species.Cilj je ove studije primjenom umjetne neuronske mreže (ANN) predvidjeti optimalne gustoće ekspandiranog polistirena (EPS) radi postizanja najboljih izolacijskih svojstava iverice proizvedene s otpadnim EPS-om umjesto s ljepilom na bazi formaldehida, kakvo se rabi u proizvodnji iverice. Stoga je za proizvodnju iverice upotrijebljen otpadni EPS pet različitih gustoća. Eksperimentalni podatci primijenjeni u studiji dobiveni su prijašnjim istraživanjem. Jedna je polovica iverja bukovine, topolovine, johovine, borovine i smrekovine osušena u sušioniku, a druga je polovica iverja kondicionirana na sobnoj temperaturi. Od osušenoga i kondicioniranog iverja proizvedene su troslojne kompozitne iverice debljine 18 mm. Toplinska vodljivost ploča određena je metodom ASTM C 518. Predikcijski model najboljih svojstava i prihvatljivih devijacija određen je statističkom i grafičkom usporedbom eksperimentalnih podataka s vrijednostima predviđenima ANN analizom. Potom su primjenom predikcijskog modela procijenjeni koeficijenti toplinske vodljivosti za one gustoće ekspandiranog polistirena koje nisu eksperimentalno ispitane. Prema toj analizi, termoizolacijska svojstva polistirenske kompozitne iverice (PCP) od bukovine i smrekovine poboljšana su pjenom od otpadnog EPS-a gustoće 30 kg/m3. Najniže vrijednosti toplinske vodljivosti za polistirensku kompozitnu ivericu od prirodno osušene topolovine, johovine i borovine dobivene su uz uporabu pjene otpadnog ESP-a gustoće 18, 13 i 22 kg/m3. Za polistirensku kompozitnu ivericu od tehnički osušenog iverja te su vrijednosti bile 15, 14 i 11-13 kg/m3. Tehničkim sušenjem iverja postignuta su znatno bolja toplinska svojstva polistirenske kompozitne iverice nego prirodnim sušenjem, a topolovina je pokazala najbolja svojstva od svih ispitivanih vrsta drva

Comparison of thermal performances of plywood shear walls produced with different thermal insulation materials

Shear walls are one of the envelopes of light-frame wooden buildings where thermal insulation is most required. The thermal performance of shear walls can vary according to the type, properties and thickness of the wood and insulation materials used in their production. In this study, it was aimed to compare the thermal performances of plywood shear walls produced with different thermal insulation materials. For this aim, the archetype walls with properties similar to commonly used plywood shear walls were designed and produced for each thermal insulation material type and wood specie. The shear wall groups were formed by using Scots pine (Pinus sylvestris), black pine (Pinus nigra) and spruce (Picea orientalis) as wood species and cellulose, flax, felt, XPS, EPS, sheep’s, rock and glass wool as thermal insulation materials. Thermal conductivity of the shear wall groups was determined according to the ASTM C518-04 standard. Thermal resistance and other thermal performance parameters were calculated using the thermal conductivity values. As a result of the study, rock wool was the best thermal insulation material among the Scots pine shear wall groups while glass wool was the best thermal insulation material among the black pine and spruce shear wall groups. The shear walls produced with EPS foam boards indicated the worst thermal performance among all group

Utjecaj materijala za oblaganje na svojstva posmičnog zida od furnirske ploče

Wooden buildings are intensely preferred especially in earthquake regions due to their many advantages such as lightness, durability, environmental friendliness, insulation and aesthetics. Shear walls provide the lateral resistance needed for light-frame wood structures to withstand earthquake loads. When sheathed with wooden structural panels such as plywood, shear walls can be strong, stiff, and ductile. This study focuses on the effects of production factors (wood species, thickness of panels) of plywood and fibre direction of sheathing material on the racking performance of the shear wall. The displacement at ultimate load decreased with increasing the thickness of plywood panels. It was also concluded that the black pine plywood panels were the best sheathing materials for the shear walls among wood species in terms of ductility. Scots pine plywood panels are the best sheathing materials for the shear walls among wood species in terms of load carrying capacity. Moreover, it was found that the wall formed perpendicular to fibre direction of sheathing materials could carry more load than the wall formed parallel to fibre direction.U potresnim su područjima osobito zastupljene drvene građevine zbog njihovih brojnih prednosti kao što su lakoća, trajnost, ekološka prihvatljivost, izolacija i estetika. Posmični zidovi osiguravaju bočnu otpornost kako bi lagane drvene konstrukcije izdržale potresna opterećenja. Kada su obloženi drvenim strukturnim pločama kao što je furnirska ploča, posmični zidovi mogu biti jaki, kruti i duktilni. Ovo je istraživanje fokusirano na učinke proizvodnih čimbenika furnirske ploče (vrstu drva, debljinu ploče) te na smjer vlakanaca materijala za oblaganje na svojstva posmičnog zida. Pokazalo se da se s povećanjem debljine furnirske ploče smanjuje pomak pri krajnjem opterećenju. Također je zaključeno da su sa stajališta duktilnosti furnirske ploče od drva crnog bora bolji izbor za oblaganje posmičnih zidova nego furnirske ploče od ostalih istraživanih vrsta drva. Sa stajališta nosivosti, za oblaganje posmičnih zidova najboljima su se pokazale furnirske ploče od drva bijelog bora. Osim toga, utvrđeno je da zid formiran okomito na smjer vlakanaca materijala za oblaganje može nositi veće opterećenje nego zid formiran paralelno sa smjerom vlakanaca materijala za oblaganje

Assessment of forest roads and firebreaks in Turkey

No Abstrac

Thrombosis with Behçet’s disease should be evaluated different conditions

No Abstract

Oslobađanje formaldehida iz uslojene drvene ploče proizvedene od furnira obrađenih usporivačima gorenja i lijepljenih dvama tipovima urea-formaldehidnih ljepila

In the present study, it was aimed to investigate the formaldehyde release of plywood panels manufactured from beech, poplar, alder and scots pine veneers treated with 5 % aqueous solutions of commonly used fire retardants: zinc borate, boric acid, monoammonium phosphate and ammonium sulfate. Two types of urea formaldehyde (UF) resin with different free formaldehyde ratios (0.16 % and 0.20 %) in adhesive were used as adhesive. Formaldehyde release of plywood panels was determined according to fl ask method described in EN 717-3 standard. As a result of this study, it was found that formaldehyde release from panels produced by beech, poplar, alder and scots pine veneers treated with zinc borate and boric acid were higher than those of control panels, while lower formaldehyde release was obtained for panels treated with monoammonium phosphate and ammonium sulfate. This is valid for all four wood species. Treatment of monoammonium phosphate and ammonium sulfate caused considerable reduction in formaldehyde emission from manufactured plywood panels. In some usage areas, where high strength properties are not expected, plywood panels manufactured from veneers treated with monoammonium phosphate and ammonium sulfate may be used for reducing formaldehyde release.U radu je predstavljeno istraživanje oslobađanja formaldehida iz uslojenih drvenih ploča proizvedenih od furnira bukve, topole, johe i običnog bora tretiranih s 5 %-tnim vodenim otopinama najčešće upotrebljavanih usporivača gorenja: cinkova borata, borne kiseline, monoamonijeva fosfata i amonijeva sulfata. Za lijepljenje furnira upotrijebljene su dvije vrste urea-formaldehidnog ljepila (UF) različitog omjera slobodnih formaldehida (0,16 i 0,20 %) u njemu. Oslobađanje formaldehida iz uslojenih drvenih ploča određeno je perforatorskom metodom opisanom u standardu EN 717-3. Istraživanja su pokazala da je oslobađanje formaldehida iz uzoraka ploča proizvedenih od furnira bukve, topole, johe i običnog bora i tretiranih cinkovim boratom i bornom kiselinom veće nego iz kontrolnih uzoraka ploča, dok je za ploče tretirane monoamonijevim fosfatom i amonijevim sulfatom ustanovljena manja količina oslobođenog formaldehida. To vrijedi za sve četiri vrste drva. Tretiranje ploča monoamonijevim fosfatom i amonijevim sulfatom rezultirala je znatnim smanjenjem emisije formaldehida iz proizvedenih uslojenih drvenih ploča. Stoga se u nekim područjima uporabe u kojima se ne zahtijeva velika čvrstoća ploča mogu upotrebljavati ploče od uslojenog drva izrađene od furnira tretiranih monoamonijevim fosfatom i amonijevim sulfatom jer se iz njih oslobađaju manje količine formaldehida

Epicardial fat thickness and cardiovascular involvements.

No Abstrac

Ankle-brachial index in coronary artery disease

Ankle-brachial index in coronary artery diseas

True knot of the umbilical cord in advanced weeks of pregnancy: a case report

True knot of the umbilical cord is a very rare condition. Usually a true knot is noticed after delivery and does not lead to problems. It is relatively less common than the other umbilical cord anomalies. Most authors agree that there is little that can be done to prevent fetal death in undiagnosed true knot. In our case, the patient gave birth to a healthy male baby weighing 2700 grams by normal vaginal delivery after an ultrasound was suggestive of intrauterine growth restriction (IUGR). The baby’s Apgar scores were 8 at one minute and 9 at five minutes. The umbilical cord measured 125 cm and contained two loose true knots. It was surprising that the baby could survive until term with these two knots and we hypothesize that this was the cause of the IUGR. Our case was interesting as neither neurologic sequela nor intrauterine death developed, despite two true umbilical cord knots