Search results for "LAV"
showing 10 items of 3985 documents
Occurrence of the LiverwortPallavicinia lyelliiin Poland
2018
Stebel, A., Fojcik, B., Rosadzinski, S. & Wierzcholska, S. 2018. Occurrence of the liverwort Pallavicinia lyellii in Poland. – Herzogia 31: 26–36.Pallavicinia lyellii, a liverwort species threatened in Europe, is a rare component of the bryoflora in Poland. This paper presents information on its 27 published and new sites, a brief discussion about ecology and threats, as well as a map of its current distribution in Poland.
New data and taxa for Orthoptera Tettigoniidae and Acrididae from tropical Africa.
2017
The results of a long-term study on the Orthoptera collected in tropical Africa and preserved in different European natural history museums are reported. Horatosphaga bazeletae n. sp. is described from South Africa, Dapanera falxcercata n. sp. from Cameroon, Eurycorypha specularia n. sp. from Zambia (Tettigoniidae Phaneropterinae), and Eucoptacra popovi n. sp. (Acrididae Coptacrinae) from the Gabon. Furthermore, the new genus Pigalua n. gen. is described for Eulioptera insularis Ragge, 1980 from Annobón Is. (Equatorial Guinea). The new tribe Kevaniellini n. trib. is proposed for Kevaniella bipunctata Chopard, 1954. Besides, the hitherto unknown males of Eurycorypha flavescens (Walker, 1869)…
Settlement dynamics and recruitment responses of Mediterranean gorgonians larvae to different crustose coralline algae species
2020
International audience; Sessile marine species such as Anthozoans act as ecosystem engineers due to their three-dimensional structure. Gorgonians, in particular, can form dense underwater forests that give shelter to other species increasing local biodiversity. In the last decades, several Mediterranean gorgonian populations have been affected by natural and anthropogenic impacts which drastically reduced their size. However, some species showed unexpected resilience, mainly due to the supply of new individuals. To understand the mechanisms underlying recovery processes, studies on the first life history stages (i.e. larval dispersal, settlement and recruitment) are needed. In tropical cora…
Regarding the influence of the particle size of crumb rubber from waste rubber on the physical and mechanical characteristics of reclaimed rubber
2017
Thus, at present, a large amount of rubber waste cannot be higher harnessed due to recovery technologies used. Also, the requirements for new products of rubber worldwide are greater than the production capacity and the availability of raw materials. To offset this balance is necessary to improve technologies for recycling waste rubber so to can get regenerated rubber with the best mechanical physical characteristics. The main technology for obtaining the regenerated rubber is based on the rubber waste shredding and making the powder, so that it can be carried out de-vulcanization in autoclave. All the time it was monitored as the de-vulcanization process to be as economical and less pollut…
Analysis of Electrical Energy Demands in Friction Stir Welding of Aluminum Alloys
2017
Abstract Manufacturing processes, as used for discrete part manufacturing, are responsible for a substantial part of the environmental impact of products. Despite that, most of metalworking processes are still poorly documented in terms of environmental footprint. To be more specific, the scientific research has well covered conventional machining processes, concerning the other processes there is a lack of knowledge in terms of environmental load characterization instead. The present paper aims to contribute to fill this knowledge gap and an energetic analysis of Friction Stir welding (FSW) is presented. Following the CO2PE! methodological approach, power studies and a preliminary time stu…
Advancing manufacturing systems research at NAMRC 46
2018
Research on manufacturing systems is further enriched and becomes stronger at the 46th North American Manufacturing Research Conference (NAMRC 46) at Texas A&M University, College Station, TX, USA. Advancing manufacturing systems is more prevalent than before due to recent industrial revolution (or Industry 4.0), continuous business decentralisation and needs for better overall resource efficiency and effectiveness. Manufacturers are competing in a global, dynamic marketplace that demands excellence in quality and service, throughput, innovativeness, agility in production, short response time to changing markets, and tight profitable margins. In the 21st century, manufacturing will be g…
Energy demand reduction of aluminum alloys recycling through friction stir extrusion processes implementation
2019
Abstract Aluminum alloys are characterized by high-energy demands for primary production. Recycling is a well-documented strategy to lower the environmental impact of light alloys production. Despite that, conventional recycling processes are still energy-intensive with a low energy efficiency. Also, permanent material losses occur during remelting because of oxidation. Recently, several solid-state recycling approaches have been analyzed; in fact, by avoiding the remelting step both energy and material can be saved and, therefore, the embodied energy of secondary production can be substantially reduced. In this paper, the solid-state approach Friction Stir Extrusion (FSE) is analyzed for a…
Towards criteria for sustainable process selection: On the modelling of pure subtractive versus additive/subtractive integrated manufacturing approac…
2017
Additive Manufacturing (AM) processes can be counted among the disruptive technologies that are capable of transforming conventional manufacturing routes. The ability to create complex geometries, the reduction in material scraps during manufacturing, and the light-weighting due to the think-additive redesign of the components represent the main points of strength of AM. However, for some applications (such as the production of metal components for the automotive and aerospace industries), the surface finishing and dimensional/geometrical part tolerancing that can be achieved via AM processes might not be adequate to satisfy the imposed product specifications, and finish machining operation…
Weld quality prediction in linear friction welding of AA6082-T6 through an integrated numerical tool
2016
Abstract A numerical and an experimental campaign were carried out with varying oscillation frequency and interface pressure. The local values of the main field variables at the contact interface between the specimens were predicted by a Lagrangian, implicit, thermo-mechanical FEM model and used as input of a dedicated Neural Network (NN). The NN, integrated in the FEM environment, was designed in order to calculate both a Boolean output, indicating the occurrence of welding, and a continuous output, indicating the quality of the obtained solid state weld. The analysis of the obtained results allowed three different levels of bonding quality, i.e., no weld, sound weld and excess of heat, to…
Effect of the mutual position between weld seam and reinforcement on the residual stress distribution in Friction Stir Welding of AA6082 skin and str…
2016
Abstract In the paper, a numerical and experimental study was carried out to highlight the effect of the distance d between the weld seam and the reinforcement on the residual stress distribution in Friction Stir Welded AA6082-T6 structures. An L-shaped profile was welded to a sheet metal with varying tool rotation and distance d from the weld seam. The Cut Compliance method was used to determine the resulting longitudinal residual stress. A dedicated FE model for FSW was set up, validated and utilized to predict the longitudinal residual stress in the assembled part. The analysis allowed the identification of a few design guidelines in order to reduce the detrimental effects of the residua…