12,174 research outputs found

    Optimization of measurement configurations for geometrical calibration of industrial robot

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    The paper is devoted to the geometrical calibration of industrial robots employed in precise manufacturing. To identify geometric parameters, an advanced calibration technique is proposed that is based on the non-linear experiment design theory, which is adopted for this particular application. In contrast to previous works, the calibration experiment quality is evaluated using a concept of the user-defined test-pose. In the frame of this concept, the related optimization problem is formulated and numerical routines are developed, which allow user to generate optimal set of manipulator configurations for a given number of calibration experiments. The efficiency of the developed technique is illustrated by several examples.Comment: arXiv admin note: text overlap with arXiv:1211.610

    A primary survey of aphid species on almond and peach, and natural enemies of Brachycaudus amygdalinus in As-Sweida, Southern Syria

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    Syria is one of the biggest almond producer country in the world. Few arthropdes that live on almond are consider as pests. Aphids are one of the major pests their. In order to change the product to organic we should know more about the pests and their natural enemies in order to use better bio- and organic decisions. A field survey was done to aphids that attack Almond and Peach in Al-Arab mountain at As- Sweida governorate, between 2002 and 2006. Three species of aphids were considered as important pests on both trees. They are Brachycaudus amygdalinus and Brachycaudus helichrysi, which are aphids that feed on the young leaves causing stunted growth; and Pterochloroides persicae which is a species that attack the bark and excretes large quantities of honeydew. A survey of natural enemies of B. amygdalinus has been done in addition to study its population dynamics during the seasons of 2002, 2003 and 2004. 30 species of natural enemies were recorded includes 15 Coccinellidae, 4 of each Anthocoridae and Miridae, 3 of Syrphidae, one species of each of Chrysopidae and Chamaemyiidae, and one beetle, in addition to one parasitoid. Some Arachinids were also mentioned to prey on this aphid. Most numerous predator at the beginning of the season was Coccinella septempunctata followed later with Scymnus (Pullus) subvillosus and Hyppodamia variegate. Most numerous predatory bug was Orius horvathi

    Optimization study for high speed radial turbine with special reference to design variables

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    Numerical results of a theoretical investigation are presented to provide information about the effect of variation of the different design and operating parameters on radial inflow turbine performance. The effects of variations in the mass flow rate, rotor tip Mach number, inlet flow angles, number of rotor blades and hub to shroud radius ratio, on the internal fluid dynamics of turbine rotors, was investigated. A procedure to estimate the flow deviation angles at the turbine exit is also presented and used to examine the influence of the operating conditions and the rotor geometrical configuration on these deviations. The significance of the results obtained is discussed with respect to improved turbine performance

    A calculation procedure for viscous flow in turbomachines, volume 2

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    Turbulent flow within turbomachines having arbitrary blade geometries is examined. Effects of turbulence are modeled using two equations, one expressing the development of the turbulence kinetic energy and the other its dissipation rate. To account for complicated blade geometries, the flow equations are formulated in terms of a nonorthogonal boundary fitted coordinate system. The analysis is applied to a radial inflow turbine. The solution obtained indicates the severity of the complex interaction mechanism that occurs between the different flow regimes (i.e., boundary layers, recirculating eddies, separation zones, etc.). Comparison with nonviscous flow solutions tend to justify strongly the inadequacy of using the latter with standard boundary layer techniques to obtain viscous flow details within turbomachine rotors. Capabilities and limitations of the present method of analysis are discussed

    A calculation procedure for viscous flow in turbomachines, volume 1

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    A method for analyzing the nonadiabatic viscous flow through turbomachine rotors is presented. The field analysis is based upon the numerical integration of the full incompressible stream function vorticity form of the Navier-Stokes equations, together with the energy equation, over the rotor blade-to-blade stream channels. The numerical code used to solve the governing equations employs a nonorthogonal boundary fitted coordinate system that suits the most complicated blade geometries. A numerical scheme is used to carry out the necessary integration of the elliptic governing equations. The flow characteristics within the rotor of a radial inflow turbine are investigated over a wide range of operating conditions. The calculated results are compared to existing experimental data. The flow in a radial compressor is analyzed in order to study the behavior of viscous flow in diffusing cascades. The results are compared qualitatively to known experimental trends. The solution obtained provides insight into the flow phenomena in this type of turbomachine. It is concluded that the method of analysis is quite general and gives a good representation of the actual flow behavior within turbomachine passages

    Double Higgs peak in the minimal SUSY B-L model

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    Motivated by a ∼3σ\sim 3\sigma excess recorded by the CMS experiment at the LHC around a mass of order ∼137\sim 137 GeV in ZZ→4lZZ\to 4l and γγ\gamma\gamma samples, we analyse the discovery potential of a second neutral Higgs boson in the Supersymmetric B−LB-L extension of the Standard Model (BLSSM) at the CERN machine. We confirm that a double Higgs peak structure can be generated in this framework, with CP-even Higgs boson masses at ∼125\sim125 GeV and ∼137\sim137 GeV, unlike the case of the Minimal Supersymmetric Standard Model (MSSM).Comment: 7 pages, 4 figures. Improved discussion of experimental dat

    Neutrinos as cosmic messengers

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    I briefly review the current status of neutrino oscillation parameters and discuss the role of neutrinos as cosmological probes, that could possibly induce the baryon asymmetry as well as the dark matter in the Universe. I comment on the origin of neutrino masses in seesaw-type and low-scale models and mention some of their laboratory signals.Comment: 14 pages AIP proceedings of 4th International Workshop on the Dark Side of the Universe (DSU08) Conference, Cairo, macros included, 20 figure files, 13 figure

    An investigation of viscous losses in radial inflow turbine nozzles

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    A theoretical model is developed to predict losses in radial inflow turbine nozzles. The analysis is presented in two parts. The first one evaluates the losses which occur across the vaned region of the nozzle, while the second part deals with the losses which take place in the vaneless field. It is concluded that the losses in a radial nozzle would not be greatly affected by the addition of a large vaneless space

    A calculation procedure for viscous flow in turbomachines, volume 3

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    A method for analyzing the nonadiabatic viscous flow through turbomachine blade passages was developed. The field analysis is based upon the numerical integration of the full incompressible Navier-Stokes equations, together with the energy equation on the blade-to-blade surface. A FORTRAN IV computer program was written based on this method. The numerical code used to solve the governing equations employs a nonorthogonal boundary fitted coordinate system. The flow may be axial, radial or mixed and there may be a change in stream channel thickness in the through-flow direction. The inputs required for two FORTRAN IV programs are presented. The first program considers laminar flows and the second can handle turbulent flows. Numerical examples are included to illustrate the use of the program, and to show the results that are obtained
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