The contribution of innovations in total factor productivity of organic olive enterprises

This paper measures the contribution of innovations in total factor productivity(TFP) of organic olive farmers. By constructing an innovation variable instead of the use of a time trend, technical change is replaced by technical difference and TFP growth becomes TFP difference. Primary cross section data on organic olive enterprises from a Greek region is used in the application of the restricted frontier profit function. Farmers are classified into groups according to their innovative ‘profile’. TFP difference among consecutive innovation groups is decomposed into technical difference and adjustment in innovativeness effects. Furthermore, efficiency differences among innovation groups are estimated. Results indicate that more innovative farmers perform better than less innovative ones regarding TFP and efficiency scores. Adoption of innovations has a positive contribution in the reduction of inefficiency and profit-loss. The rate of technical difference is always positive in the formulation of TFP difference whereas the adjustment in innovativeness effects varies among the innovation groups. Finally, high-tech capital is more or less under-utilized, regardless of the innovation group.Innovations, total factor productivity, profit efficiency, organic farming, Greece, Productivity Analysis,

PECULIARITIES AND USEFULNESS OF MULTIPLIERS, ELASTICITIES AND LOCATION QUOTIENTS FOR THE REGIONAL DEVELOPMENT PLANNING: AN OTHER VIEW

In this paper, the peculiarities of type I multipliers and elasticities and their differences on the generated results for the proposed developmental priorities are examined. Moreover the influences of the used non-survey techniques (Simple Location Quotient, Cross Industry Location Quotient and Flegg’s Location Quotient) among the sectoral rankings from the type I multipliers and elasticities are scrutinized. For the target of the paper, the economy of Western Macedonia region in Greece has been used as an example for the secondary simulation. The results show that the type I multipliers and elasticities are not end up to same sectoral rankings due to their different definition and are not the same suitable indicators for short-term and long-term developmental planning. Nevertheless, their coexistence could improve the economic prosperity both on short and long period of time. As for the used location quotient, the FLQ technique improves the proximity of the sectoral rankings that are generated from all the used indicators and also reduces the magnitudes of type I multipliers and elasticities.Input-output analysis, regional planning, multipliers, elasticities, non-survey techniques

Transmitter Beam Bias Verification for Optical Satellite Data Downlinks with Open-Loop Pointing – the 3-OGS-Experiment

Optical free-space data downlinks from LEO satellites benefit considerably from reduced effort on the space segment, when a dedicated pointing mechanism and active tracking of a ground beacon can be avoided. Instead, the attitude of the satellite is dynamically determined from its star cameras and other sensors. Initial calibration for this technique requires recording of the spatial and temporal beam distribution on the Earth’s surface. We describe the measurement of the beam intensity on ground by the power detectors of three ground stations in parallel, exemplarily for one specific downlink. From this data we derive the instantaneous center of gravity of the beam spot, and its dynamic movement during the downlink. By comparison with the satellite’s own recorded attitude data and its error, the dynamic offset to be corrected on the satellite can be calculated, resulting in optimized pointing-control for future operational open-loop downlinks

Identification of plastic constitutive parameters at large deformations from three dimensional displacement fields

The aim of this paper is to provide a general procedure to extract the constitutive parameters of a plasticity model starting from displacement measurements and using the Virtual Fields Method. This is a classical inverse problem which has been already investigated in the literature, however several new features are developed here. First of all the procedure applies to a general three-dimensional displacement field which leads to large plastic deformations, no assumptions are made such as plane stress or plane strain although only pressure-independent plasticity is considered. Moreover the equilibrium equation is written in terms of the deviatoric stress tensor that can be directly computed from the strain field without iterations. Thanks to this, the identification routine is much faster compared to other inverse methods such as finite element updating. The proposed method can be a valid tool to study complex phenomena which involve severe plastic deformation and where the state of stress is completely triaxial, e.g. strain localization or necking occurrence. The procedure has been validated using a three dimensional displacement field obtained from a simulated experiment. The main potentialities as well as a first sensitivity study on the influence of measurement errors are illustrated

A generalisation of the Hill's quadratic yield function for planar plastic anisotropy to consider loading direction

© 2017 The Authors In this work, a new generalised quadratic yield function for plane stress analysis that is able to describe the plastic anisotropy of metals and also the asymmetric behaviour in tension-compression typical of the Hexagonal Closed-Pack (HCP) materials, is developed. The new yield function has a quadratic form in the stress tensor and it simultaneously predicts the r-values and directional flow stresses, which is shown to agree very well with experimental results. It also accurately describes the biaxial symmetric stress state which is fundamental for the accurate modelling of aluminium alloys. The new quadratic yield function represents the non-symmetric biaxial stress state by performing a linear interpolation from pure uniaxial loading to a biaxial symmetric stress state. The main advantages of this new yield function is that it can be used for the modelling of metals with any crystallographic structure (BCC, FCC or HCP), it only has five anisotropic coefficients and also that it is a simple quadratic yield criterion that is able to accurately reproduce the plastic anisotropy of metals whilst using an associated flow rule

Influence of the characteristics of the experimental data set used to identify anisotropy parameters

This work presents an investigation into the effect of the number and type of experimental input data used in parameter identification of Hill’48, Barlat’91 (Yld91) and Cazacu and Barlat’2001 (CB2001) yield criteria on the accuracy of the finite element simulation results. Different sets of experimental data are used to identify the anisotropy parameters of two metal sheets, exhibiting different anisotropic behaviour and hardening characteristics: a mild steel (DC06) and an aluminium alloy (AA6016-T4). Although it has been shown that the CB2001 yield criterion can lead to an accurate description of anisotropic behaviour of metallic sheets, its calibration requires a large set of experimental input data. A calibration procedure is proposed for CB2001 based on a reduced set of experimental data, i.e. where the results are limited to three uniaxial tensile tests, combined with artificial data obtained using the Barlat’91 yield criterion. Evaluation of the predictive capacity of the studied yield criteria, calibrated using different sets of experimental data, is made by comparing finite element simulation results with experimental results for the deep drawing of a crossshaped part. A satisfying agreement is observed between experimental and numerical thickness distributions, with a negligible effect of the number and type of experimental data for the Hill’48 and Yld91 yield criteria. On the contrary, CB2001 calibration is quite sensitive to the experimental data available, particularly biaxial values. Nevertheless, CB2001 calibration based on the combination of effective and artificial experimental data achieves satisfying results, which in the worst case are similar to the ones obtained with the Yld91.The authors gratefully acknowledge the financial support of the Portuguese Foundation for Science and Technology (FCT) via the projects PTDC/EMS-TEC/1805/2012 and PEst-C/EME/UI0285/2013 and by FEDER funds through the program COMPETE – Programa Operacional Factores de Competitividade, under the project CENTRO-07-0224-FEDER-002001 (MT4MOBI). The first author is also grateful for the Post-Doc grant.info:eu-repo/semantics/publishedVersio

Influence of boundary conditions on the prediction of springback and wrinkling in sheet metal forming

The high-strength steel sheets currently used in the automotive industry are prone to non-traditional behaviour during forming, being wrinkling and springback two of the most challenging geometrical predictions for numerical simulation. Thus, the finite element method requires accurate and reliable numerical models. This study presents the experimental and numerical analysis of a rail component with high tendency to develop wrinlding and 2D springback. Two different materials are used for the sheet blank, namely a mild steel (DC06) and a dual phase steel (DP600). The frictional behaviour between each metallic sheet and the forming tools is evaluated through the flat-die test, allowing the determination of a friction coefficient as a function of the normal pressure. The influence of the applied boundary conditions on the numerical results is evaluated by means of two distinct numerical models (full blank geometry and 1/4 of the blank with symmetry conditions). The results show that the wrinkling behaviour is strongly affected by the blanks material, as well as by the symmetry conditions defined in the numerical model. In fact, considering the full model of the blank, the numerical results are in better agreement with the experimental ones. However, the computational cost of the numerical simulation considering the full blank is substantially higher than using 1/4 of the blank.The authors gratefully acknowledge the financial support of the Portuguese Foundation for Science and Technology (FCT) under the projects with reference P2020-PTDC/EMS-TEC/0702/2014 (POCI-010145-FEDER-016779) and P2020-PTDC/EMS-TEC/6400/2014 (POCI01-0145-FEDER-016876) by UE/FEDER through the program COMPETE 2020. The first author is also grateful to the FCT for the Postdoctoral grant SFRH/BPD/101334/2014.info:eu-repo/semantics/publishedVersio