One-Dimensional Control System for a Linear Motor of a Two-Dimensional Nanopositioning Stage Using Commercial Control Hardware

A two-dimensional (2D) nanopositioning platform stage (NanoPla) is in development at the University of Zaragoza. To provide a long travel range, the actuators of the NanoPla are four Halbach linear motors. These motors present many advantages in precision engineering, and they are custom made for this application. In this work, a one-dimensional (1D) control strategy for positioning a Halbach linear motor has been developed, implemented, and experimentally validated. The chosen control hardware is a commercial Digital Motor Control (DMC) Kit from Texas Instruments that has been designed to control the torque or the rotational speed of rotative motors. Using a commercial control hardware facilitates the applicability of the developed control system. Nevertheless, it constrains the design, which needs to be adapted to the hardware and optimized. Firstly, a dynamic characterization of the linear motor has been performed. By leveraging the dynamic properties of the motor, a sensorless controller is proposed. Then, a closed-loop control strategy is developed. Finally, this control strategy is implemented in the control hardware. It was verified that the control system achieves the working requirements of the NanoPla. It is able to work in a range of 50 mm and perform a minimum incremental motion of 1 mu m

Development of a computer program to simulate the predictions of the replaced elements model of Pavlovian conditioning

Vogel, E.H. Universidad de Talca, Escuela de Psicología, Casilla N° 747, Talca, Chile. Disponible http://www.psicothema.com/pdf/3392.pdfPese a la aparente simpleza del condicionamiento pavloviano, la investigación acerca de sus mecanismos ha despertado considerable debate, como es el caso de la disputa acerca de si los estímulos que se asocian son codificados en forma >(un estímulo compuesto es equivalente a la suma de sus componentes) o >(un estímulo compuesto es un ejemplar único). Esta controversia es evidente en la abundante investigación sobre las predicciones contrastantes de los modelos elementalistas y configuracionales. Recientemente, han surgido soluciones mixtas, con las ventajas de ambos enfoques, pero difíciles de evaluar dada su complejidad. Este artículo presenta un programa computacional para ejecutar simulaciones de un modelo mixto (replaced elements model o REM). Se incluyen instrucciones y ejemplos para utilizar el simulador con fines investigativos y educacionales

Grader Bias in Cattle Markets? Evidence from Iowa

Live cattle are increasingly priced as an explicit function of U.S. Department of Agriculture yield and quality grades. Human graders visually inspect each slaughtered carcass and call grades in a matter of seconds as the carcass passes on a moving trolley. We examine whether there is systematic bias in grade calls using a sample of loads delivered to three different midwestern packing plants during 2000–2002. Overall, results indicate that indeed there is a bias, and that grading standards vary significantly across packing plants. Results also are consistent with a behavioral model where graders are more accurate when grading relatively low-quality carcasses

Analysis of the Machinability of Carbon Fiber Composite Materials in Function of Tool Wear and Cutting Parameters Using the Artificial Neural Network Approach

[EN] Local delamination is the most undesirable damage associated with drilling carbon fiber reinforced composite materials (CFRPs). This defect reduces the structural integrity of the material, which affects the residual strength of the assembled components. A positive correlation between delamination extension and thrust force during the drilling process is reported in literature. The abrasive effect of the carbon fibers modifies the geometry of the fresh tool, which increases the thrust force and, in consequence, the induced damage in the workpiece. Using a control system based on an artificial neural network (ANN), an analysis of the influence of the tool wear in the thrust force during the drilling of CFRP laminate to reduce the damage is developed. The spindle speed, feed rate, and drill point angle are also included as input parameters of the study. The training and testing of the ANN model are carried out with experimental drilling tests using uncoated carbide helicoidal tools. The data were trained using error-back propagation-training algorithm (EBPTA). The use of the neural network rapidly provides results of the thrust force evolution in function of the tool wear and cutting parameters. The obtained results can be used by the industry as a guide to control the impact of the wear of the tool in the quality of the finished workpiece.The Ministry of Economy and Competitiveness of Spain, projects DPI2017-89197-C2-1-R and DPI2017-89197-C2-2-R] and the Ministry of Science, Innovation and Universities, grant number [FJCI-2017-34910], funded this research.Feito-Sánchez, N.; Muñoz-Sánchez, A.; Diaz-Alvarez, A.; Loya, J. (2019). Analysis of the Machinability of Carbon Fiber Composite Materials in Function of Tool Wear and Cutting Parameters Using the Artificial Neural Network Approach. Materials. 12(17):1-13. https://doi.org/10.3390/ma12172747S1131217Huang, X. (2009). Fabrication and Properties of Carbon Fibers. Materials, 2(4), 2369-2403. doi:10.3390/ma2042369Yang, Y., Jiang, Y., Liang, H., Yin, X., & Huang, Y. (2019). Study on Tensile Properties of CFRP Plates under Elevated Temperature Exposure. Materials, 12(12), 1995. doi:10.3390/ma12121995Liu, D., Tang, Y., & Cong, W. L. (2012). A review of mechanical drilling for composite laminates. Composite Structures, 94(4), 1265-1279. doi:10.1016/j.compstruct.2011.11.024Hocheng, H., & Tsao, C. . (2003). Comprehensive analysis of delamination in drilling of composite materials with various drill bits. Journal of Materials Processing Technology, 140(1-3), 335-339. doi:10.1016/s0924-0136(03)00749-0Hocheng, H., & Tsao, C. C. (2006). Effects of special drill bits on drilling-induced delamination of composite materials. International Journal of Machine Tools and Manufacture, 46(12-13), 1403-1416. doi:10.1016/j.ijmachtools.2005.10.004Hocheng, H., & Tsao, C. C. (2005). The path towards delamination-free drilling of composite materials. Journal of Materials Processing Technology, 167(2-3), 251-264. doi:10.1016/j.jmatprotec.2005.06.039Davim, J. ., & Reis, P. (2003). Study of delamination in drilling carbon fiber reinforced plastics (CFRP) using design experiments. Composite Structures, 59(4), 481-487. doi:10.1016/s0263-8223(02)00257-xSardiñas, R. Q., Reis, P., & Davim, J. P. (2006). Multi-objective optimization of cutting parameters for drilling laminate composite materials by using genetic algorithms. Composites Science and Technology, 66(15), 3083-3088. doi:10.1016/j.compscitech.2006.05.003Fernandes, M., & Cook, C. (2006). Drilling of carbon composites using a one shot drill bit. Part I: Five stage representation of drilling and factors affecting maximum force and torque. International Journal of Machine Tools and Manufacture, 46(1), 70-75. doi:10.1016/j.ijmachtools.2005.03.015Fernandes, M., & Cook, C. (2006). Drilling of carbon composites using a one shot drill bit. Part II: empirical modeling of maximum thrust force. International Journal of Machine Tools and Manufacture, 46(1), 76-79. doi:10.1016/j.ijmachtools.2005.03.016Feito, N., Diaz-Álvarez, A., Cantero, J. L., Rodríguez-Millán, M., & Miguélez, H. (2015). Experimental analysis of special tool geometries when drilling woven and multidirectional CFRPs. Journal of Reinforced Plastics and Composites, 35(1), 33-55. doi:10.1177/0731684415612931Feito, N., Díaz-Álvarez, J., Díaz-Álvarez, A., Cantero, J., & Miguélez, M. (2014). Experimental Analysis of the Influence of Drill Point Angle and Wear on the Drilling of Woven CFRPs. Materials, 7(6), 4258-4271. doi:10.3390/ma7064258Iliescu, D., Gehin, D., Gutierrez, M. E., & Girot, F. (2010). Modeling and tool wear in drilling of CFRP. International Journal of Machine Tools and Manufacture, 50(2), 204-213. doi:10.1016/j.ijmachtools.2009.10.004Abrão, A. M., Rubio, J. C. C., Faria, P. E., & Davim, J. P. (2008). The effect of cutting tool geometry on thrust force and delamination when drilling glass fibre reinforced plastic composite. Materials & Design, 29(2), 508-513. doi:10.1016/j.matdes.2007.01.016Rawat, S., & Attia, H. (2009). Wear mechanisms and tool life management of WC–Co drills during dry high speed drilling of woven carbon fibre composites. Wear, 267(5-8), 1022-1030. doi:10.1016/j.wear.2009.01.031Fernández-Pérez, J., Cantero, J. L., Díaz-Álvarez, J., & Miguélez, M. H. (2017). Influence of cutting parameters on tool wear and hole quality in composite aerospace components drilling. Composite Structures, 178, 157-161. doi:10.1016/j.compstruct.2017.06.043Tsao, C. C., & Hocheng, H. (2007). Effect of tool wear on delamination in drilling composite materials. International Journal of Mechanical Sciences, 49(8), 983-988. doi:10.1016/j.ijmecsci.2007.01.001Chen, W.-C. (1997). Some experimental investigations in the drilling of carbon fiber-reinforced plastic (CFRP) composite laminates. International Journal of Machine Tools and Manufacture, 37(8), 1097-1108. doi:10.1016/s0890-6955(96)00095-8Murphy, C., Byrne, G., & Gilchrist, M. D. (2002). The performance of coated tungsten carbide drills when machining carbon fibre-reinforced epoxy composite materials. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 216(2), 143-152. doi:10.1243/0954405021519735Fernández-Pérez, J., Cantero, J., Díaz-Álvarez, J., & Miguélez, M. (2019). Hybrid Composite-Metal Stack Drilling with Different Minimum Quantity Lubrication Levels. Materials, 12(3), 448. doi:10.3390/ma12030448Tsao, C. ., & Hocheng, H. (2004). Taguchi analysis of delamination associated with various drill bits in drilling of composite material. International Journal of Machine Tools and Manufacture, 44(10), 1085-1090. doi:10.1016/j.ijmachtools.2004.02.019Palanikumar, K., Prakash, S., & Shanmugam, K. (2008). Evaluation of Delamination in Drilling GFRP Composites. Materials and Manufacturing Processes, 23(8), 858-864. doi:10.1080/10426910802385026Mohan, N. S., Kulkarni, S. M., & Ramachandra, A. (2007). Delamination analysis in drilling process of glass fiber reinforced plastic (GFRP) composite materials. Journal of Materials Processing Technology, 186(1-3), 265-271. doi:10.1016/j.jmatprotec.2006.12.043Srinivasa Rao, B., Rudramoorthy, R., Srinivas, S., & Nageswara Rao, B. (2008). Effect of drilling induced damage on notched tensile and pin bearing strengths of woven GFR-epoxy composites. Materials Science and Engineering: A, 472(1-2), 347-352. doi:10.1016/j.msea.2007.03.023Enemuoh, E. U., El-Gizawy, A. S., & Chukwujekwu Okafor, A. (2001). An approach for development of damage-free drilling of carbon fiber reinforced thermosets. International Journal of Machine Tools and Manufacture, 41(12), 1795-1814. doi:10.1016/s0890-6955(01)00035-9Saravanan, M., Ramalingam, D., Manikandan, G., & Kaarthikeyen, R. R. (2012). Multi Objective Optimization of Drilling Parameters Using Genetic Algorithm. Procedia Engineering, 38, 197-207. doi:10.1016/j.proeng.2012.06.027Feito, N., Milani, A. S., & Muñoz-Sánchez, A. (2015). Drilling optimization of woven CFRP laminates under different tool wear conditions: a multi-objective design of experiments approach. Structural and Multidisciplinary Optimization, 53(2), 239-251. doi:10.1007/s00158-015-1324-yKrishnaraj, V., Prabukarthi, A., Ramanathan, A., Elanghovan, N., Senthil Kumar, M., Zitoune, R., & Davim, J. P. (2012). Optimization of machining parameters at high speed drilling of carbon fiber reinforced plastic (CFRP) laminates. Composites Part B: Engineering, 43(4), 1791-1799. doi:10.1016/j.compositesb.2012.01.007Krishnamoorthy, A., Rajendra Boopathy, S., Palanikumar, K., & Paulo Davim, J. (2012). Application of grey fuzzy logic for the optimization of drilling parameters for CFRP composites with multiple performance characteristics. Measurement, 45(5), 1286-1296. doi:10.1016/j.measurement.2012.01.008Abhishek, K., Datta, S., & Mahapatra, S. S. (2014). Optimization of thrust, torque, entry, and exist delamination factor during drilling of CFRP composites. The International Journal of Advanced Manufacturing Technology, 76(1-4), 401-416. doi:10.1007/s00170-014-6199-3El Kadi, H. (2006). Modeling the mechanical behavior of fiber-reinforced polymeric composite materials using artificial neural networks—A review. Composite Structures, 73(1), 1-23. doi:10.1016/j.compstruct.2005.01.020Altinkok, N., & Koker, R. (2004). Neural network approach to prediction of bending strength and hardening behaviour of particulate reinforced (Al–Si–Mg)-aluminium matrix composites. Materials & Design, 25(7), 595-602. doi:10.1016/j.matdes.2004.02.014Karnik, S. R., Gaitonde, V. N., Rubio, J. C., Correia, A. E., Abrão, A. M., & Davim, J. P. (2008). Delamination analysis in high speed drilling of carbon fiber reinforced plastics (CFRP) using artificial neural network model. Materials & Design, 29(9), 1768-1776. doi:10.1016/j.matdes.2008.03.014Altinkok, N., & Koker, R. (2006). Modelling of the prediction of tensile and density properties in particle reinforced metal matrix composites by using neural networks. Materials & Design, 27(8), 625-631. doi:10.1016/j.matdes.2005.01.005Stone, R., & Krishnamurthy, K. (1996). A neural network thrust force controller to minimize delamination during drilling of graphite-epoxy laminates. International Journal of Machine Tools and Manufacture, 36(9), 985-1003. doi:10.1016/0890-6955(96)00013-2Kuo, C.-F. J., Chang, C.-D., Su, T.-L., & Fu, C.-T. (2008). Optimization of the Dyeing Process and Prediction of Quality Characteristics on Elastic Fiber Blending Fabrics. Polymer-Plastics Technology and Engineering, 47(7), 678-687. doi:10.1080/03602550802129569Chen, W.-C., Fu, G.-L., Tai, P.-H., & Deng, W.-J. (2009). Process parameter optimization for MIMO plastic injection molding via soft computing. Expert Systems with Applications, 36(2), 1114-1122. doi:10.1016/j.eswa.2007.10.020Ko, Y.-D., Moon, P., Kim, C. E., Ham, M.-H., Myoung, J.-M., & Yun, I. (2009). Modeling and optimization of the growth rate for ZnO thin films using neural networks and genetic algorithms. Expert Systems with Applications, 36(2), 4061-4066. doi:10.1016/j.eswa.2008.03.010Faraz, A., Biermann, D., & Weinert, K. (2009). Cutting edge rounding: An innovative tool wear criterion in drilling CFRP composite laminates. International Journal of Machine Tools and Manufacture, 49(15), 1185-1196. doi:10.1016/j.ijmachtools.2009.08.002Ashrafi, H. R., Jalal, M., & Garmsiri, K. (2010). Prediction of load–displacement curve of concrete reinforced by composite fibers (steel and polymeric) using artificial neural network. Expert Systems with Applications, 37(12), 7663-7668. doi:10.1016/j.eswa.2010.04.076Levenberg, K. (1944). A method for the solution of certain non-linear problems in least squares. Quarterly of Applied Mathematics, 2(2), 164-168. doi:10.1090/qam/10666Khashaba, U. A., El-Sonbaty, I. A., Selmy, A. I., & Megahed, A. A. (2010). Machinability analysis in drilling woven GFR/epoxy composites: Part II – Effect of drill wear. Composites Part A: Applied Science and Manufacturing, 41(9), 1130-1137. doi:10.1016/j.compositesa.2010.04.011Heisel, U., & Pfeifroth, T. (2012). Influence of Point Angle on Drill Hole Quality and Machining Forces When Drilling CFRP. Procedia CIRP, 1, 471-476. doi:10.1016/j.procir.2012.04.084Díaz-Álvarez, A., Díaz-Álvarez, J., Santiuste, C., & Miguélez, M. H. (2019). Experimental and numerical analysis of the influence of drill point angle when drilling biocomposites. Composite Structures, 209, 700-709. doi:10.1016/j.compstruct.2018.11.01

Chapter 07: Vulnerability of macroalgae of the Great Barrier Reef to climate change

Assessing the vulnerability of benthic macroalgae is complicated by the fact that the taxon ‘algae’ is an unnatural (and, some suggest, outdated) grouping that encompasses several distinct and diverse evolutionary lines. Adl et al.3 suggest that ‘algae’ remains a useful functional term, denoting photosynthetic protists and their multicellular derivatives which are not embryophytes (higher plants), as well as cyanobacteria. However, they also show that ‘algae’, like ‘protists’, is not a formal taxon (and therefore should not be capitalised), nor a single, homogeneous group.This is Chapter 7 of Climate change and the Great Barrier Reef: a vulnerability assessment. The entire book can be found at http://hdl.handle.net/11017/13

The tan(beta) - M_H^\pm bound from inclusive semi-tauonic B-decays in the MSSM

We compute the O(alpha_s) SUSY-QCD corrections to the W and charged Higgs mediated inclusive semi-tauonic B-decay, B->tau antineutrino_tau X. Combining the SUSY contribution with the SM result obtained from the heavy quark effective field theory, plus ordinary QCD corrections, we find that the allowed region in the (tan(beta),M_H^\pm)-plane could be significantly modified by the short-distance supersymmetric effects. Since the sensitivity to the SUSY parameters other than mu (the higgsino mixing mass) is rather low, the following effective bound emerges for mu<0 at the 2 sigma level: tan(beta)~< 0.43 (M_H^\pm/GeV). Remarkably, for mu>0 there could be no bound at all. Finally, we provide a combined (tan(beta,M_H^\pm) exclusion plot using our B-meson results together with the recent data from top quark decays.Comment: 15 pages, LaTeX, 1 table and 3 figs included as a separate file, full postscript version avaliable at ftp://ftp.ifae.es/preprint/ft/uabft407.ps . New comments and references added. Accepted version in Phys. Lett.

Pulsatile flow in coronary bifurcations for different stenting techniques

The objective of this work is to analyze the local hem odynamic changes caused in a coronary bifurcation by three different stenting techniques: simple stenting of the main vessel, simple stenting of the main vessel with kissing balloon in the side branch and culotte. To carry out this study an idealized geometry of a coronary bifurcation is used, and two bifurcation angles, 45º and 90º, are chosen as representative of the wide variety of re al configurations. In order to quantify the influence of the stenting technique on the local blood flow, both numeri- cal simulations and experimental measurements are performed. First, steady simulations are carried out with the commercial code ANSYS-Fluent, and then, experimental measurements with PIV (Particle Image Velocimetry) obtained in the laboratory are used to validate the numerical simulation. The steady computational simulations show a good overall agreement with the experimental data. Second, pulsatile flow is considered to take into account the tran- sient effects. The time averaged wall shear stress, scillatory shear index and pressure drop obtained numerically are used to compare the behavior of the stenting techniques