244 research outputs found

    Diffusion controlled corrosion in gas sparged systems

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    The rate of diffusion - controlled corrosion of the walls of rectangular bubble column and a liquid has been studied with the copper dissolution technique. Variables studied were superficial air velocity, initial height of solution in the column, physical properties of the solution and the presence of suspended solids with different concentrations and different particle size. The rate of diffusion - controlled corrosion in solution free solids was given by the equation J = 0.232 (Fr .Re)-0.22 (L/de)-0.169 while for the presence of suspended solids, the data were correlated by the equation J = 0.171 (Fr .Re)-0.214(L/d p) 0.187 The presence of suspended solids increases the rate of diffusion - controlled corrosion by an amount ranging from 5 to 16 %

    Behavior of bonded and unbonded prestressed normal and high strength concrete beams

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    AbstractThe major disadvantage of using ordinary reinforced concrete (RC) elements is the corrosion of steel, which occurs due to effect of cracks in tension zones. The main advantage of the fully prestressed concrete system is the absence of cracks in the concrete at the nominal service load and therefore better durability will be achieved. Combining the PC system with the use of high strength concrete is a milestone, which will potentially result in a new design approach. The disadvantage of the use of this combination is referred to the reduced ductility of concrete members.This paper presents an experimental program conducted to study the behavior of bonded and unbounded prestressed normal strength (NSC) and high strength concrete (HSC) beams. The program consists of a total of nine beams; two specimens were reinforced with non-prestressed reinforcement, four specimens were reinforced with bonded tendons, and the remaining three specimens were reinforced with unbonded tendons. The overall dimensions of the beams are 160×340×4400-mm. The beams were tested under cyclic loading up to failure to examine its flexural behavior. The main variables in this experimental program are nominal concrete compressive strength (43, 72 and 97MPa), bonded and unbonded tendons and prestressing index (0%, 70% and 100%). Theoretical analysis using rational approach was also carried out to predict the flexural behavior of the specimens. Evaluation of the analytical work is introduced and compared to the results of the experimental work

    Egg parasitoids of the genus Trichogramma (Hymenoptera, Trichogrammatidae) in olive groves of the Mediterranean region

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    A survey of egg parasitoids of the genus Trichogramma (Hymenoptera, Trichogrammatidae) was carried out in olive groves in Portugal, Greece, Egypt, and Tunisia during the years 2002–2004. Parasitoids were obtained either by exposing sentinel eggs (Sitotroga cerealella Olivier or Ephestia kuehniella Zeller) on olive trees or by collecting eggs of lepidopterous olive pests. Parasitized egg samples were reared separately in the laboratory for emergence of parasitoids. These were further reared in separate lines and processed by morphological and molecular biology techniques for species characterization. The recorded fauna of Trichogramma parasitoids in olive groves was species poor and consisted of species mainly known from the Mediterranean region. Trichogramma bourarachae Pintureau and Babault was found in Tunisia and Egypt, T. cordubensis Vargas and Cabello, and T. euproctidis Girault in Egypt, Trichogramma cacoeciae Marchal in Portugal, Greece, Egypt, Tunisia and Trichogramma nerudai Pintureau and Gerding in Portugal. Apart from that, Trichogramma oleae Voegele´ and Pointel was collected in Tunisia. This species is probably not indigenous, but has established after several releases of a French strain were made in recent years. For selected strains, the sequence of the internal transcribed spacer 2 (ITS-2) region of rDNA was determined and deposited in the GenBank database. Differences in important biological attributes were found among collected strains of T. bourarachae, suggesting the existence of biotypes. The results contribute to the limited knowledge on distribution and biodiversity of the genus Trichogramma in the Mediterranean region. They can be helpful for the preservation and use of indigenous Trichogramma species in biological control of lepidopterous pests in olive and other local crops

    Triphelio – an international research project for sustainable control of lepidopterous pests in olive groves.

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    The olive moth (Prays oleae, Lepidoptera: Plutellidae) is known as one of the key pests in olive cultivation. In particular areas, also the jasmine moth (Pal pita zmionalis, Lepidoptera: Pyralidae) can cause serious damage to both leaves and fiuits of the olive tree. Both pests are mainly controlled by insecticide applications. In November 200 I, an international research project was started to promote biological and biotechnical methods for the control of these pests

    Mechanical stability of the CMS strip tracker measured with a laser alignment system

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    Search for massive resonances decaying in to WW,WZ or ZZ bosons in proton-proton collisions at root s=13 TeV

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    Search for R-parity violating supersymmetry with displaced vertices in proton-proton collisions at root s=8 TeV

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