Search results for "Cutting"
showing 10 items of 164 documents
Some observations on metal cutting with reference to the mechanical characteristics of working materials
1972
The hypothesis of the minimum work of Merchant is applied to materials with different yield points in traction and in simple compression on the assumption that these materials yield in accordance with the paraboloid yield-criterion. The experimental data obtained from cutting tests like those described in this paper may apparently be in good agreement with theoretical results. But closer examination reveals that the values of the shear angle φ depend largely on the cutting speed and on the feed p. r. All relationship between φ and (λ — γ) (difference between the friction angle on the rake face and the rake angle) must therefore take in account the influence of the above variables.
Plenērs kā caurviju prasmes veicinoša mācību metode
2022
Plenērs kā mācību metode un mācību vide, kā izglītojošs un mērķcentrētu prasmju attīstošs aktivitāšu kopums tradicionāli tiek saistīts ar vizuālās mākslas jomu un nozarēm. Lai veicinātu plenēra, kā ārpustelpu mācību metodes un vides aktualitāti dažādās mācību jomās nepieciešams klasificēt caurviju prasmju metožu kopumu. Izveidot ieteikumus un starpnozaru, starpdisciplinārus mācību metožu moduļus ieteicamus skolotājiem un izglītojošu pasākumu kuratoriem Fenomenoloģiska pētījuma ietvaros veikta situācijas izpēte, daudzveidīgu brīvdabas aktivitāšu pieredzes apkopojums un analīze. Definēti daudzveidīgi kognitīvās spējas stimulējoši mācību stratēģijas moduļi , kuri demonstrē caurviju prasmes iet…
Forage production, N uptake, N2 fixation, and N recovery of berseem clover grown in pure stand and in mixture with annual ryegrass under different ma…
2011
In Mediterranean countries, forage grasses and legumes are commonly grown in mixture because of their ability to increase herbage yield and quality compared with monocrop systems. However, the benefits of intercropping over a monocrop system are not always realized because the efficiency of a grass–legume mixture is strongly affected by agronomic factors. The present study evaluated productivity, N2 fixation, N transfer, and N recovery of berseem clover (Trifolium alexandrinum) grown in pure stand and in mixture with annual ryegrass (Lolium multiflorum) under high or low defoliation frequencies and varying plant arrangements (sowing in the same row or in alternating rows). On average, the b…
Basal heat improves adventitious root quality in Plumeria (Plumeria rubra L.) stem cuttings of different sizes
2014
Root development of hardwood cuttings of Plumeria rubra was investigated in relation to basal heat and the size of cuttings. Terminal cuttings of a clone grown in Sicily were trimmed to various lengths, ranging from 10 to 26 cm. To verify the cutting rooting response to basal heat, half of the cuttings were placed on a basal heated bench (28 ± 3°C, constant temperature) while the remaining were placed on an unheated bench (16-18°C during the night and 20-22°C during the day). Percent rooting and cutting survival were not affected by basal heat and cutting length. However, basal heat positively affected number of roots, length of longest root and bud growth. Increases in the length of the cu…
Mercury uptake into poplar leaves
2016
International audience; Tailings dumps require mercury stabilization to prevent air pollution by evaporated mercury, which can be achieved through plant covers. Plants are considered a net sink for atmospheric Hg via incorporation into leaf tissues. However, most studies related to Hg uptake by plants have considered plants exposed to only atmospheric Hg, whereas in the case of tailings dumps, plants are potentially exposed to both soil and atmospheric Hg. The goal of this work is to evaluate the relative contributions of root and atmospheric pathways by growing poplar (Populus trichocarpa X Populus maximowiczii/var Skado) cuttings on either control or polluted substrates and under either n…
Researches Regarding Optimising the Contouring Precision of CNC Laser Cutting Machines
2014
This paper presents some experimental researches regarding the manufacturing accuracy of a profiling machine together with an approach to eliminate the positioning and contouring errors. A mathematical model based on transfer functions is used as starting approach in order to tune the feed drives of the machine. The accuracy of the profiling machine is tested before and after the tuning process, in order to validate the proposed approach. There are unfolded both positioning tests along one axis and contouring tests on two axes.
Improving the Manufacturing Accuracy of the Profiling Machines
2010
Abstract This paper presents the results of theoretical and experimental researches carried out with regard to the optimization of the dynamic behavior of a CNC laser cutting machine, in terms of cutting precision, for the case of flat metallic parts whose contours comprise right angles and which a profiling machine has to process continuously, without stopping in the corner points. It is aimed especially at detailing the influence of the numerical control equipment's setup on the size of the contouring errors and on the smoothness of the movement, factors that have a direct influence on the accuracy and that have been less addressed until now. The theoretical researches indicate that it is…
Method for improving the contouring accuracy for CNC profiling machines at the shop floor level
2009
Computer Numerically Controlled (CNC) laser cutting machines are capable of producing high-quality precise parts. However, as cutting speeds is increased, in order to achieve higher productivity, the accuracy of the parts is affected. In order to improve the contouring accuracy of these machines, a simple straight-forward joint simulation and experimental strategy is proposed. The position controllers within the feed drives are considered the key factor in improving the dynamic behavior and consequently the contouring accuracy of a CNC laser cutting machine at the shop floor level.
Can changes in starch content and peroxidase activity be used as rooting phase markers for rhododendron leaf bud cuttings?
2011
We examined whether peroxidase activity in cutting bases and leaves and starch content in cutting bases can be used as rooting phase markers in the elepidote rhododendron cv. 'Babites Baltais' (Rhododendron L.). Changes in peroxidase activity in cutting leaves and bases, as well as starch content in cutting bases, were determined in relation to anatomical stages of rhizogenesis in leaf bud cuttings treated with 1% indole-3-butyric acid (IBA+) or without IBA (IBA–). The pattern of change of peroxidase activity was similar in cutting bases and leaves of IBAleaf bud cuttings. Three phases of adventitious root formation were identified: induction, initiation and expression. During the induction…
Blight Caused by Sclerotium rolfsii on Potted Ornamental Citrus in Sicily.
2019
Approximately 140,000 container-grown ornamental citrus plants are produced each year in the province of Catania (eastern Sicily). In the spring of 2006, a severe blight was observed in a commercial nursery in Catania on 2-month-old rooted cuttings of lemon (Citrus limon (L.) Burm.) and calamondin (× Citrofortunella mitis (Blanco) J. W. Ingram & H. E. Moore). Approximately 80% of the nursery stock of 2,000 cuttings was affected. Cuttings were grown in 7.5-cm2 pots made with compressed peat and wood pulp at 28 to 30°C with 95 to 100% relative humidity on benches in a greenhouse, The pot mix was composed of peat, perlite, and soil (2:1:2). Cuttings showed a dark brown necrotic lesion at …