Influence of plastic deformation on the change of electrical and mechanical properties oxygen-free (OF) copper and copper alloy wires

This article is devoted to the comparison of changes in mechanical and electrical properties due to the applied deformation of copper and copper alloy rods. Bars from four different production technologies were deformed in the drawing process, including oxygen-free (OF) copper, electrolytic copper ETP, copper from cable granulate and silver copper with a high silver content up to 15 wt. % obtained in laboratory technology. The article presents the chemical purity, physical and electrical properties of rods before deformation. The summary of the research on the selected materials are changes in mechanical properties and electrical conductivity as a function of deformation up to 3,5 on a logarithmic scale and the coefficient of electromechanical efficiency WEM

Power cycling analysis of enameled aluminium winding wires connections pprepared with the use of SHARK-Al® type connectors

The article presents the research results of current cyclic thermal tests performed on enamelled aluminium wires connections, made with the use of a new type of Shark-Al quick-connectors. In particular, the main purpose of the conducted research was to analyse the effect of cyclic heating on the contact resistance change during the tests which allows to test the stability of the connections in simulated working conditions under current flow. Tests included a total of 300 thermal cycles, of which the first 200 were carried out to the 65 °C temperature measured in the connector at above the ambient temperature, and then additional 100 cycles were performed for the temperature of the connector at 140 °C (tolerance +5 °C). During the tests, the resistance of samples was monitored, which allowed to verify the correctness of performed connections

New generation of cable screw connectors for electrical power engineering systems

The article presents a material analysis for a new generation of cable screw connectors with shear bolts designed for not only 1st and 2nd class of cables but also 5tth class of aluminium and copper conductors that have not been previously supported. The set of properties of aluminium series 6xxx designated for screw connectors production has been determined. Finite Element Method (FEM) simulation of the controlled shear of the bolt at the body of the screw connector has been carried out. The repeatability of the bolt shear in the actual conditions was also conducted in order to verify the prototypes of the new generation of cable screw connectors

New generation of cable screw connectors for electrical power engineering systems

The article presents a material analysis for a new generation of cable screw connectors with shear bolts designed for not only 1st and 2nd class of cables but also 5tth class of aluminium and copper conductors that have not been previously supported. The set of properties of aluminium series 6xxx designated for screw connectors production has been determined. Finite Element Method (FEM) simulation of the controlled shear of the bolt at the body of the screw connector has been carried out. The repeatability of the bolt shear in the actual conditions was also conducted in order to verify the prototypes of the new generation of cable screw connectors

Optimal numerical design of bucket elevators using discontinuous deformation analysis

Bucket elevators are efficient machines to transport granular materials in industrial and civil engineering applications. These materials are composed of hundreds, thousands or even more particles, the global behavior of which is defined by contact interactions. The first attempts to analyze the transportation of granular materials were treated by very simple continuum methods that do not take into account these interactions, producing simulations that do not fit the experimental results accurately. Given the internal discontinuity nature of granular media, it is reasonable to use numerical methods to model their behavior, such as discontinuous deformation analysis (DDA)-a member of the discrete element method family that started to be used in the 90s to analyze similar problems. The version of DDA used in the current work treats grains as rigid circular particles with friction, damping and eventually cohesion with the objective of simulating and analyzing in detail the discharge of granular materials with bucket elevators. A deterministic computer code has been implemented and validated against simplified analytical formulae and experimental results taken from the literature. This computer code is then used to obtain optimum two-dimensional bucket geometries under specific working conditions. The optimization aims to maximize transport distance and to minimize remaining material, taking into account bucket velocity and the properties of the grains. The resulting geometries are discussed and compared against standard designs.J.L. Perez-Aparicio, R. Bravo were partially supported by the MFOM I+D (2004/38), both by MICIIN #BIA 2008-00522 and the first also by Polytechnic University of Valencia under grant PAID 05-10-2674. J.J. Gomez-Hernandez was partially supported by MICIIN #CGL 2011-23295.Pérez Aparicio, JL.; Bravo, R.; Gómez-Hernández, JJ. (2014). Optimal numerical design of bucket elevators using discontinuous deformation analysis. Granular Matter. 16(4):485-498. https://doi.org/10.1007/s10035-014-0485-5S485498164Rademacher, F.: Non-spill discharge characteristics of bucket elevators. Powder Technol. 22(2), 215–241 (1979)Koster, K.: Bulk material discharge of bucket elevators, especially high-capacity bucket elevators. [zum schuettgutabwurf bei becherwerken, insbesondere bei hochleistungsbecherwerken]. Aufbereitungs-Technik 25(8), 450–463 (1984)Koster, K.: Use of high-capacity bucket elevators in the cement industry. [zum einsatz von hochleistungsbecherwerken in der zementindustrie]. Zement-Kalk-Gips 33(3), 116–119 (1980)Koster, K.: Development and state of the art in heavy-duty bucket elevators with central chains—part 2 [entwicklung und stand der technik von hochleistungs-becherwerken mit zentralkette—teil 2]. ZKG Int. 49(4), 173–187 (1996)Koster, K.: Centrifugal discharge of bucket elevators. Bulk Solids Handl. 5(2), 449–460 (1985)Koster, K.: Problem of complete emptying of high-speed elevator buckets. Aufbereitungs-Technik 27(9), 471–481 (1986)Korzen, Z.: Mechanics of gravitational discharge of cell-less bucket wheels in reclaiming machines. Bulk Solids Handl. 7(6), 801–812 (1987)Korzen, Z., Dudek, K.: Mathematical model of the operational efficiency of a multibucket centrifugal discharge wheel [model matematyczny wydajnosci roboczego procesu kola wieloczerpakowego z odsrodkowym wysypem]. Politechnika Warszawska Prace Naukowe Mechanika 1(121), 187–199 (1989)Shi, G., Goodman, R.: Two dimensional discontinuous deformation analysis. Int. J. Numer. Anal. Methods Geomech. 9(6), 541–556 (1985)Pérez-Aparicio, J., Bravo, R.: Discrete Elements, vol. 2, pp. 41–77. Consorcio TCN (2006)Shi, G.: Discontinuous Deformation Analysis: A New Model for the Statics and Dynamics of Block Systems. Ph.D. thesis, University of California, Berkeley (1988)Moosavi, M., Grayeli, R.: A model for cable bolt-rock mass interaction: integration with discontinuous deformation analysis (DDA) algorithm. Int. J. Rock Mech. Min. Sci. 43(4), 661–670 (2006)Pérez-Aparicio, J., Bravo, R., Ortiz, P.: Refined element discontinuous numerical analysis of dry-contact masonry arches. Eng. Struct. 48, 578–587 (2013)McBride, W., Sinnott, M., Cleary, P.: Discrete element modelling of a bucket elevator head pulley transition zone. Granul. Matter 13(2), 169–174 (2011)Kruggel-Emden, H., Sudbrock, F., Wirtz, S., Scherer, V.: Experimental and numerical investigation of the bulk behavior of wood pellets on a model type grate. Granul. Matter 14(6), 681–693 (2012)Walton, O., Moor, C., Gill, K.: Effects of gravity on cohesive behavior of fine powders: implications for processing lunar regolith. Granul. Matter 9(5), 353–363 (2007)Gao, Y., Muzzio, F., Ierapetritou, M.: Optimizing continuous powder mixing processes using periodic section modeling. Chem. Eng. Sci. 80, 70–80 (2012)Shmulevich, I.: State of the art modeling of soil-tillage interaction using discrete element method. Soil Tillage Res. 111(1), 41–53 (2010)Moon, T., Oh, J.: A study of optimal rock-cutting conditions for hard rock tbm using the discrete element method. Rock Mech. Rock Eng. 45(5), 837–849 (2012)Makokha, A., Moys, M., Bwalya, M., Kimera, K.: A new approach to optimising the life and performance of worn liners in ball mills: experimental study and DEM simulation. Int. J. Miner. Process. 84(1–4), 221–227 (2007)Balevičius, R., Kačianauskas, R., Mroz, Z., Sielamowicz, I.: Discrete element method applied to multiobjective optimization of discharge flow parameters in hoppers. Struct. Multidiscip. Optim. 31(3), 163–175 (2006)Hu, L.: Gradual deformation and iterative calibration of Gaussian-related stochastic models. Math. Geol. 32(1), 87–108 (2000)Bravo, R., Pérez-Aparicio, J., Laursen, T.: An energy consistent frictional dissipating algorithm for particle contact problems. Int. J. Numer. Methods Eng. 92(9), 753–781 (2012)Belytschko, T., Liu, W., Moran, B.: Nonlinear Finite Elements for Continua and Structures. Wiley, New York (2000)Beckert, R., Föll, R.: Untersuchung der abwurfverhältnisse an kettenbecherwerken. Förden Heben 1(15), 833–836 (1966)Jaskulski, A.: Engineer-to-order approach to high speed bucket elevator design in a small-enterprise. Appl. Eng. Agric. 24(5), 545–557 (2008)Beverley, G.: Mechanics of High Speed Bucket Elevator Discharge. Ph.D. thesis. University of Newcastle (1986)Beverley, G., Roberts, A., Hayes, J.: Mechanics of high speed elevator discharge. Bulk Solids Handl. 3(4), 853–859 (1983)Korzen, Z., Dudek, K.: Reclaiming with a high-speed bucket wheel with centrifugal discharge. Bulk Solids Handl. 11(3), 615–626 (1991)Bravo, R., Pérez-Aparicio, J., Laursen, T.: An enhanced energy conserving time stepping algorithm for frictionless particle contacts. Int. J. Numer. Methods Eng. 85(11), 1415–1435 (2011)Jaskulski, A.: Methodology of Multi-Criteria Optimization of Appliances for Vertical Grain Transportation. Ph.D. thesis. Warsaw University of Technology (1992

A Re-Evaluation of the nuclear Structure Function Ratios for D, He, Li, C and Ca

We present a re-evaluation of the structure function ratios F2(He)/F2(D), F2(C)/F2(D) and F2(Ca)/F2(D) measured in deep inelastic muon-nucleus scattering at an incident muon momentum of 200 GeV. We also present the ratios F2(C)/F2(Li), F2(Ca)/F2(Li) and F2(Ca)/F2(C) measured at 90 GeV. The results are based on data already published by NMC; the main difference in the analysis is a correction for the masses of the deuterium targets and an improvement in the radiative corrections. The kinematic range covered is 0.0035 < x < 0.65, 0.5 < Q^2 <90 GeV^2 for the He/D, C/D and Ca/D data and 0.0085 < x < 0.6, 0.84 < Q^2 < 17 GeV^2 for the Li/C/Ca ones.Comment: 6 pages, Latex, 3 figures as uuencoded compressed tar file included at the end, in case of problems contact [email protected] (Antje Bruell

Percepção dos consumidores relativamente à carne de bovino: critérios de escolha a partir de grupos de discussão

Nas economias desenvolvidas, a segurança dos alimentos, o bem‑estar animal e o ambiente têm vindo a assumir relevância nas preocupações dos consumidores. Procurámos saber, através da metodologia dos grupos de discussão (focus groups) realizados em duas cidades de Portugal, Lisboa e Porto, as preocupações e perceções dos consumidores relativamente a estes atributos, os quais são essencialmente acreditados. Este conhecimento é fundamental para a aplicação posterior de métodos de preferências declaradas. Foi ainda possível obter, com base em exercícios de seleção entre carnes diferenciadas, e através de um modelo logit, intervalos de preços passíveis de serem utilizados posteriormente na definição de cenários em experiências de escolha (método de preferências declaradas) -----ABSTRACT-----In developed economies, food safety, animal welfare and the environment have become relevant consumers’ concerns. We conducted several focus groups in two Portuguese cities, Lisboa and Porto, in order to get participants perceptions and concerns for these attributes, which are essentially credence attributes. This knowledge is critical for the subsequent application of stated preference methods. It was also possible to estimate, based on exercises of selection among different meats, and through a logit model, price ranges that could be used in the definition of scenarios for choice experiments (stated preference method)info:eu-repo/semantics/publishedVersio