Mechanical characterization of coir epoxy composites and effect of processing methods on mechanical properties

Abstract: Composite materials have now attracted wide acceptance in product development and manufacture especially in automotive and aerospace applications where weight reduction and low fuel consumption are critical product performance metrics. In most applications, glass and carbon fibre composites are used. However, natural fibre composites also offer attractive properties. They are competitive especially in terms of price and density when compared to glass and carbon fibre composites while providing similar mechanical properties. Commonly available natural fibres include coir and sisal. Resin transfer moulding (RTM) process is also an established technique for manufacturing composites as it offers good surface finish and dimensional control. The aim of this paper is to investigate the effect of resin transfer rate on the performance of the product. Coir fibre / epoxy resin composites are prepared using RTM for differing resin transfer rates and fibre fraction for treated and untreated fibres. The results obtained indicate a slight reduction in performance with reduction in resin transfer rate. However, stiffness remained unaffected. Improvement in stiffness and strength with increasing volume fraction was reported which was in agreement with literature. However, the data exhibited an optimum fibre volume fraction of 30% beyond which performance deteriorated. This investigation indicates that further work is required to optimise the production of natural fibre composites using RTM

Influence of manufacturing conditions on fatigue life of welded joints

Abstract: This paper presents a study on the influence of manufacturing conditions on the fatigue life of welded joints of high strength steels P355NL-1 and P355NL-2. Welding conditions were varied by adjusting the welding parameters and component-welding positions for a range of railway bogie welded joints. Prepared joints were then assessed for cracks and porosity defects. It was observed that an increase in welding speed resulted in an increase in crack and pore sizes. The same applied to increase in welding angle. Identified crack sizes ranged from 0.2 to 2.6 mm. Impact of such defects on fatigue life was assessed by evaluating the residual fatigue life of the component using the Paris law for stress amplitude of 150 MPa. The fatigue life of the bogie was estimated to be 6.23 × 105 instead of the required 1 × 106 cycles. It was concluded that manufacturing conditions have a significant effect on fatigue life of high strength steel welded joints. Travel speed and welding angle are critical

Effect of Wood-derived Charcoal Content on Properties of Wood Plastic Composites

The effect of wood-derived charcoal flour on the water resistance and mechanical properties of wood plastic composite (WPC) panels was investigated. The hot press molded WPC panels were produced from polypropylene (37 wt%) with maleic anhydride-grafted polypropylene (MAPP, 3 wt%) and different mixtures of wood flour and charcoal flour. The amount of charcoal flour was gradually increased up to 60 wt%. The thickness swelling and water absorption of WPC panels considerably decreased with increasing charcoal flour content. The internal bond strength and bending properties of the WPC panels significantly improved with increasing charcoal flour content. This was mainly attributed to the high amount of pores and gaps in the charcoal flour. Melted polypropylene could get into the pores and gaps during the hot press molding, which lead to a better interfacial adhesion between polymer matrix and wood filler. The results showed that the charcoal flour could be partially substituted for the wood flour in the production of WPC panels having higher dimensional stability and internal bond strength

Exchange of nutrients and oxygen across the sediment-water interface below a Sparus aurata marine fish farm in the north-western Mediterranean Sea

Purpose: This study analyzes the effects of aquaculture activities in open seawater in the north-western coastal waters of the Mediterranean Sea. It is the first of its kind to be based on benthic flux data gathered in situ below fish farms for this particular area. Materials and methods: Samples were collected on four sampling campaigns over a 1-year cycle under a Sparus aurata fish farm facility where benthic fluxes were measured in situ using light and dark benthic chambers. Bottom water and sediment samples were also collected. Data were compared to those for a nearby control station. Results and discussion: Significant differences were found (ANOVA, p < 0. 05) between concentrations of organic matter (OM), total phosphorus and redox potentials in sediments located under the cages and those of the control station. The consumption of dissolved oxygen (DO) by sediment and positive ammonium (NH4 +) fluxes was stimulated by OM content, with correlations of r = -0. 60 (p < 0. 01) and r = 0. 70 (p < 0. 01), respectively. The OM content of sediments was found to be consistently higher under the cages than at the control station, with the highest value (1. 8 ± 0. 7 %) under the cages observed during the early summer; values of DO and NH4 + fluxes were -64 ± 17 and 12. 7 ± 1. 0 mmol m-2 day-1, respectively. PO4 3- fluxes were consistently higher in the fish farm sediments (between 0. 58 and 0. 98 mmol m-2 day-1) than those observed at the control station. Nitrate (NO3 -) fluxes were found to be consistently negative due to denitrification occurring in the sediments and were related to the concentration of NO3 - in bottom waters (r = 0. 92, p < 0. 01). Si fluxes were shown to be associated with water temperature (r = 0. 59, p < 0. 05). Conclusions: The results imply that sediments located below cages accumulate organic matter originating from aquaculture activities, especially during summer months when this activity increases. Sediments undergo biogeochemical changes that mainly affect fluxes of DO, NH4 + and soluble reactive phosphorus, although these do not seem to have a significant impact on the quality of the water column due to the hydrodynamic characteristics of the area. © 2012 Springer-Verlag.We would like to thank the Caja del Mediterraneo for a predoctoral fellowship fund for this research and Antonio Asuncion Acuigroup Maremar manager for the facilities and support in conducting the study. The translation of this paper was funded by the Universidad Politecnica de Valencia, Spain. We are grateful for the valuable comments of the anonymous reviewers on previous versions of the manuscript.Morata Higón, T.; Sospedra, J.; Falco Giaccaglia, SL.; Rodilla Alama, M. (2012). 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J Appl Ichthyol 18:129–133Borja A, Rodríguez JG, Black K, Bodoy A, Emblow C, Fernandes TF, Forte J, Karakassis I, Muxika I, Nickell TD, Papageorgiou N, Pranovi F, Sevastou K, Tomassetti P, Angel D (2009) Assessing the suitability of a range of benthic indices in the evaluation of environmental impact of fin and shellfish aquaculture located in sites across Europe. Aquaculture 293:231–240Cermelj B, Ogrinc N, Faganeli J (2001) Anoxic mineralization of biogenic debris in near-shore marine sediments (Gulf of Trieste, northern Adriatic). Sci Total Environ 266:143–152Dell’Anno A, Mei ML, Pusceddu A, Danovaro R (2002) Assessing the trophic state and eutrophication of coastal marine systems: a new approach based on the biochemical composition of sediment organic matter. Mar Pollut Bull 44:611–622Dosdat A (2001) Environmental impact of aquaculture in the Mediterranean: nutritional and feeding aspects. Environmental impact assessment of Mediterranean aquaculture farms. 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Hydrobiologia 587:25–36Pergent-Martini C, Boudouresque CF, Pasqualini V, Pergent G (2006) Impact of fish farming facilities on Posidonia oceanica meadows: a review. Mar Ecol 27:310–319Pitta P, Karakassis I, Tsapakis M, Zivanovic S (1999) Natural versus mariculture induced variability in nutrients and plankton in the Eastern Mediterranean. Hydrobiologia 391:181–194Redfield AC, Ketchum BH, Richards FA (1963) The influence of organisms on the composition of seawater. In: Hill MN (ed) The sea, vol 2. Interscience, New YorkRiise JC, Roos N (1997) Benthic metabolism and the effects of bioturbation in a fertilized polyculture fish pond in northeast Thailand. Aquaculture 150:45–62Rodríguez J (1999) Ecología. Ed. Pirámide. pp 411Sakamaki T, Nishimura O, Sudo R (2006) Tidal time-scale variation in nutrient flux across the sediment-water interface of an estuarine tidal flat. 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Subregional DXA-derived vertebral bone mineral measures are stronger predictors of failure load in specimens with lower areal bone mineral density, compared to those with higher areal bone mineral density

Measurement of areal bone mineral density (aBMD) in intravertebral subregions may increase the diagnostic sensitivity of dual-energy X-ray absorptiometry (DXA)-derived parameters for vertebral fragility. This study investigated whether DXA-derived bone parameters in vertebral subregions were better predictors of vertebral bone strength in specimens with low aBMD, compared to those with higher aBMD. Twenty-five lumbar vertebrae (15 embalmed and 10 fresh-frozen) were scanned with posteroanterior- (PA) and lateral-projection DXA, and then mechanically tested in compression to ultimate failure. Whole-vertebral aBMD and bone mineral content (BMC) were measured from the PA- and lateral-projection scans and within 6 intravertebral subregions. Multivariate regression was used to predict ultimate failure load by BMC, adjusted for vertebral size and specimen fixation status across the whole specimen set, and when subgrouped into specimens with low aBMD and high aBMD. Adjusted BMC explained a substantial proportion of variance in ultimate vertebral load, when measured over the whole vertebral area in lateral projection (adjusted R2 0.84) and across the six subregions (ROIs 2–7) (adjusted R2 range 0.58–0.78). The association between adjusted BMC, either measured subregionally or across the whole vertebral area, and vertebral failure load, was increased for the subgroup of specimens with identified ‘low aBMD’, compared to those with ‘high aBMD’, particularly in the anterior subregion where the adjusted R2 differed by 0.44. The relative contribution of BMC measured in vertebral subregions to ultimate failure load is greater among specimens with lower aBMD, compared to those with higher aBMD, particularly in the anterior subregion of the vertebral body

Review of experimental methods to determine spontaneous combustion susceptibility of coal – Indian context

This paper presents a critical review of the different techniques developed to investigate the susceptibility of coal to spontaneous combustion and fire. These methods may be sub-classified into the two following areas: (1) Basic coal characterisation studies (chemical constituents) and their influence on spontaneous combustion susceptibility. (2) Test methods to assess the susceptibility of a coal sample to spontaneous combustion. This is followed by a critical literature review that summarises previous research with special emphasis given to Indian coals

Mining industry and sustainability

20th International Mining Congress and Exhibition of Turkey (IMCET 2007) -- JUN 06-08, 2007 -- Ankara, TURKEYWOS: 000248289300028From the seventies, the concept of sustainable development (SD) has undergone various changes and more recently has begun to be understood as a development activities of modem industrial activities including mining sector. Due to the mainstream definition from the Brundtland commision report, SD is: a concept of needs, an idea of limitation, a future oriented paradigm, and a dynamic process of change and it says "development that meets the needs of the present without compromising the ability of future generations to meet their own needs". SD, which has emerged as the prevailing paradigm for balansing society's environment, social and economic goals, offers a framework within which the appropriate combination of consumption and preservation can be sought. However, there are many alternative definitions of SD, each reflecting a different political and philosophical perspective. In this paper, foresights from literature dealing with relationship of sutainable development and mining are review and an assessment was implemented by using some statistical data for energy and coal industry in Turkey.Sci & Technol Res Council Turkey, Turkish Coal Enterprises, Eti Mine Works Gen Management, Turkish Hardcoal Enterprises, Yildizlar Holding, Black Sea Copper Works, Eti Copper Corp, Dedeman Holding, Chamber Mining Engineers Turke

Bezpieczeństwo systemów zasilania w przemyśle kolejowym

Within its structure railway transportation systems contain very critical subsystems that can seriously harm the system itself, people or the environment if not properly controlled. Therefore, these critical subsystems are analysed according to the related standards and necessary safety functions are implemented, verified and operated. On the other hand, railway power supply system, which is a critical subsystems, is generally properly analysed from a reliability perspective whereas the corresponding safety related functions are roughly examined. This paper proposes that the railway power supply systems should be considered as safety critical systems and justifies this proposal using risk analysis as presented in the standard IEC 61508. The safety related functions of the system are examined and each function is modelled in detail using Markov modelling method. These models are implemented over a power supply system of Istanbul Transportation Co. and SIL values of the safety functions are calculated using these modular and easily adaptable Markov models. Furthermore the obtained results are compared with simplistic Fault Tree analysis (FTA) and the significance of accurate calculation is demonstrated.W skład struktury kolejowych systemów transportowych wchodzą krytyczne podsystemy, które, nieodpowiednio monitorowane, mogą narażać sam system, a także ludzi oraz środowisko na poważne szkody. Dlatego też, podsystemy krytyczne analizuje się zgodnie z odpowiednimi normami oraz wdraża w nich, weryfikuje i realizuje niezbędne funkcje bezpieczeństwa. W przypadku systemów zasilania kolei, które należą do grupy podsystemów krytycznych, system na ogół analizuje się dokładnie z punktu widzenia niezawodności, natomiast funkcje bezpieczeństwa bada się jedynie pobieżnie. W prezentowanej pracy postuluje się że systemy zasilania kolei powinny być traktowane jako krytyczne dla bezpieczeństwa, co autorzy uzasadniają z wykorzystaniem analizy ryzyka przedstawionej w normie IEC 61508. W proponowanym rozwiązaniu, bada się funkcje bezpieczeństwa systemu, przy czym każda funkcja zostaje szczegółowo zamodelowana za pomocą metody modelowania Markowa. Modele tego typu wdrożono w systemie zasilania firmy Istanbul Transportation Co. Wartości poziomu nienaruszalności bezpieczeństwa (SIL) badanych funkcji bezpieczeństwa obliczano za pomocą wspomnianych modularnych modeli Markowa charakteryzujących się łatwością adaptacji. Ponadto, uzyskane wyniki porównano z symplistyczną analizą drzewa błędów (FTA), a także wykazano znaczenie prowadzenia dokładnych obliczeń

Late Cretaceous to Recent kinematics of SE Anatolia (Turkey)

Five different deformation phases have been recognized in the SE Anatolian orogen and the Arabian Platform based on palaeostress inversion studies using fault-slip data sets. The timing and duration of these phases are determined using various criteria including the age of the affected strata, syndepositional structures, cross-cutting structures and overprinting slickensides. The oldest deformation phase is characterized generally by NE-SW-directed extension. The extension is thought to have resulted from slab-roll back processes during the Maastrichtian to Middle Eocene interval (c. 60 Ma to 40-35 Ma). The second deformation phase is characterized by east-west to NW-SE-directed compression and thought to result from cessation of roll-back processes possibly due to subduction of younger oceanic crust or increase in the convergence rate between Africa and Eurasia during the post-Middle Eocene to Late Oligocene interval (c. 40-35 Ma to 25 Ma). The third deformation phase is characterized by east-west to NW-SE-directed extension possibly due to slab detachment that initiated in Iran and migrated westwards during the latest Oligocene to Middle Miocene period (25-11 Ma). The fourth deformation phase is characterized by approximately north-south-directed compression due to collision and further northwards indentation of Arabian Plate by the end of Middle Miocene (11-3.5 Ma). The fifth and present deformation phase is characterized by NE-SW compression which might result from tectonic re-organization in the region since the Middle Pliocene (c. 3.5 Ma to recent)