Parameterisation and reliability of the functional reach test in people who suffer stroke

AIM: The aim of this study is to analyse the reliability, sensitivity and specificity of the parameterisation of FRT using inertial sensors to record kinematic variables in subjects who have had a stroke. Our hypothesis is that the IS will be reliable instruments for kinematic study of the FRT. METHODS: This is a cross-sectional study of 5 subjects over 65 years who suffer of stroke. During the execution of Funtional Reach Test the subjects carried two inertial sensors, one was placed in the lumbar and the other in the trunk. After analysing the data obtained in the kinematic registration by inertial sensors a number of direct and indirect variables were obtained. The variables extracted directly from FRT through the IS were distance, maximun angular lumbosacral/thoracic displacement, time maximun angular lumbosacral/thoracic displacement, time return starting position and total time. Using this data the speed and the acceleration of each one of them were calculated. A descriptive analysis of all kinematic outcomes recorded by the two inertial sensors was developed (trunk and lumbar) and the average range achieved in the FRT. Reliability measures were calculated by analysing the internal consistency the measures with 95% confidence interval of each outcome variable. The reliability was calculated in the functional reach and the outcomes measured by the IS. RESULTS: The values in the the Functional Reach Test obtained in the present study (2.06 ± 12.75cm) are similar to those obtained in other studies with this population and in the same age range. Intrasubject reliability values observed in the use of inertial sensors are all located above 0.820, ranging from 0.829 (time B_C lumbar area) and 0.891 (A_B displacement of the trunk). Likewise, the observed intersubject values range from 0.821 (Time B_C lumbar area) and 0.883 (B_C trunk displacement). On the other hand, the reliability of the FRT was 0.987 (0.983-0.992) and 0.983 (0.979-0.989) intersubject and intrasubject respectively. CONCLUSION: The main conclusion that can be reached is that the inertial sensors are a tool with excellent reliability, validity, sensitivity and specificity in the parameterisation of the Functional Reach Test in people who have had a stroke.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Organ-Dedicated Molecular Imaging Systems

[EN] In this review, we will cover both clinical and technical aspects of the advantages and disadvantages of organ specific (dedicated) molecular imaging (MI) systems, namely positron emission tomography (PET) and single photon emission computed tomography, including gamma cameras. This review will start with the introduction to the organ-dedicated MI systems. Thereafter, we will describe the differences and their advantages/disadvantages when compared with the standard large size scanners. We will review time evolution of dedicated systems, from first attempts to current scanners, and the ones that ended in clinical use. We will review later the state of the art of these systems for different organs, namely: breast, brain, heart, and prostate. We will also present the advantages offered by these systems as a function of the special application or field, such as in surgery, therapy assistance and assessment, etc. Their technological evolution will be introduced for each organ-based imager. Some of the advantages of dedicated devices are: higher sensitivity by placing the detectors closer to the organ, improved spatial resolution, better image contrast recovery (by reducing the noise from other organs), and also lower cost. Designing a complete ring-shaped dedicated PET scanner is sometimes difficult and limited angle tomography systems are preferable as they have more flexibility in placing the detectors around the body/organ. Examples of these geometries will be presented for breast, prostate and heart imaging. Recently achievable excellent time of flight capabilities below 300-ps full width at half of the maximum reduce significantly the impact of missing angles on the reconstructed images.This work was supported in part by the European Research Council through the European Union's Horizon 2020 Research and Innovation Program under Grant 695536, in part by the EU through the FP7 Program under Grant 603002, and in part by the Spanish Ministerio de Economia, Industria y Competitividad through PROSPET (DTS15/00152) funded by the Ministerio de Economia y Competitividad under Grant TEC2016-79884-C2-1-R.González Martínez, AJ.; Sánchez, F.; Benlloch Baviera, JM. (2018). Organ-Dedicated Molecular Imaging Systems. IEEE Transactions on Radiation and Plasma Medical Sciences. 2(5):388-403. https://doi.org/10.1109/TRPMS.2018.2846745S3884032

Inter-rater and intra-rater reliability of the extended TUG test in elderly participants

Background: To analyse the reliability, variance and execution time of the Extended Timed Up and Go (Extended TUG) test in three age groups of elderly participants (G1: 55–64 years; G2: 65–74 years; G3: 75–85 years). Methods: An analytical cross-sectional study of 114 recruited participants (63 women) of average age 70.17 (± 7.3) years was undertaken. Each participant performed the Extended TUG three consecutive times, with a rest break between tests of 120 s. Both the intragroup and intergroup reliability of the measurements in the Extended TUG were analysed. Results: The reliability of the Extended TUG test is excellent for the first and second decades but drops down to good for the third decade. Specifically, intragroup reliability ranged from 0.784 for G3 to 0.977 for G1 (G2 = 0.858). Intergroup reliability, compared with intragroup reliability, was slightly lower, ranging between 0.779 for G3 and 0.972 for G1 (G2 = 0.853). Conclusion: The reliability of the Extended TUG test progressively decreases with increasing age, being excellent for the younger age groups and good for the oldest age group

In-depth evaluation of TOF-PET detectors based on crystal arrays and the TOFPET2 ASIC

[EN] In recent years high efforts have been devoted to enhance spatial and temporal resolutions of PET detectors. However, accurately combining these two main features is, in most of the cases, challenging. Typically, a compromise has to be made between the number of readout channels, scintillator type and size, and photosensors arrangement if aiming for a good system performance, while keeping a moderate cost. In this work, we have studied several detector configurations for PET based on a set of 8x8 Silicon Photomultiplier (SiPMs) of 3x3 mm(2) active area, and LYSO crystal arrays with different pixel sizes. An exhaustive evaluation in terms of spatial, energy and timing resolution was made for all detector configurations. In some cases, when using pixel sizes different than SiPM active area, a significant amount of scintillation light may spread among several SiPMs. Therefore, we made use of a calibration method considering the different SiPM timing contributions. Best Detector Time Resolution (DTR) of 156 ps FWHM was measured when using 3x3 mm(2) crystal pixels directly coupled to the 3x3 mm(2) SiPMs. However, when using 1.5 mm crystal pixels with the same photosensor array, although we could clearly resolve all crystal pixels, an average DTR of 250 ps FWHM was achieved. We also shed light in this work on the timing dependency of the crystal pixel and photosensor alignment.This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 695536) and by the Spanish Ministerio de Economia, Industria y Competitividad under Grant TEC2016-79884-C2-1-R. The first author has also been supported by Generalitat Valenciana, Spain under grant agreement GRISOLIAP-2018-026.Lamprou, E.; Sánchez Martínez, F.; Benlloch Baviera, JM.; González Martínez, AJ. (2020). In-depth evaluation of TOF-PET detectors based on crystal arrays and the TOFPET2 ASIC. Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment. 977:1-8. https://doi.org/10.1016/j.nima.2020.164295S18977Jones, T., & Townsend, D. (2017). History and future technical innovation in positron emission tomography. Journal of Medical Imaging, 4(1), 011013. doi:10.1117/1.jmi.4.1.011013Surti, S. (2014). Update on Time-of-Flight PET Imaging. Journal of Nuclear Medicine, 56(1), 98-105. doi:10.2967/jnumed.114.145029Lecoq, P. (2017). Pushing the Limits in Time-of-Flight PET Imaging. IEEE Transactions on Radiation and Plasma Medical Sciences, 1(6), 473-485. doi:10.1109/trpms.2017.2756674Surti, S., & Karp, J. S. (2016). Advances in time-of-flight PET. Physica Medica, 32(1), 12-22. doi:10.1016/j.ejmp.2015.12.007Gundacker, S., Auffray, E., Pauwels, K., & Lecoq, P. (2016). Measurement of intrinsic rise times for various L(Y)SO and LuAG scintillators with a general study of prompt photons to achieve 10 ps in TOF-PET. Physics in Medicine and Biology, 61(7), 2802-2837. doi:10.1088/0031-9155/61/7/2802González-Montoro, A., Sánchez, F., Bruyndonckx, P., Cañizares, G., Benlloch, J. M., & González, A. J. (2019). Novel method to measure the intrinsic spatial resolution in PET detectors based on monolithic crystals. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 920, 58-67. doi:10.1016/j.nima.2018.12.056Moses, W. W. (2011). Fundamental limits of spatial resolution in PET. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 648, S236-S240. doi:10.1016/j.nima.2010.11.092Lamprou, E., Gonzalez, A. J., Sanchez, F., & Benlloch, J. M. (2020). Exploring TOF capabilities of PET detector blocks based on large monolithic crystals and analog SiPMs. Physica Medica, 70, 10-18. doi:10.1016/j.ejmp.2019.12.004Lamprou, E., Aguilar, A., González-Montoro, A., Monzó, J. M., Cañizares, G., Iranzo, S., … Benlloch, J. M. (2018). PET detector block with accurate 4D capabilities. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 912, 132-136. doi:10.1016/j.nima.2017.11.002A. Di Francesco, R. Bugalho, L. Oliveira, L. Pacher, A. Rivetti, M. Rolo, et al. TOFPET2: A high-performance ASIC for time and amplitude measurements of SiPM signals in time-of-flight applications, J. Instrum. 11 (03) C03042.Van Dam, H. T., Borghi, G., Seifert, S., & Schaart, D. R. (2013). Sub-200 ps CRT in monolithic scintillator PET detectors using digital SiPM arrays and maximum likelihood interaction time estimation. Physics in Medicine and Biology, 58(10), 3243-3257. doi:10.1088/0031-9155/58/10/3243V. Nadig, D. Schug, B. Weissler, V. Schulz, Evaluation Of The PETsys TOFPET2 ASIC In Multi-Channel Coincidence Experiments, arXiv:1911.08156.Gundacker, S., Turtos, R. M., Auffray, E., Paganoni, M., & Lecoq, P. (2019). High-frequency SiPM readout advances measured coincidence time resolution limits in TOF-PET. Physics in Medicine & Biology, 64(5), 055012. doi:10.1088/1361-6560/aafd52Gundacker, S., Acerbi, F., Auffray, E., Ferri, A., Gola, A., Nemallapudi, M. V., … Lecoq, P. (2016). State of the art timing in TOF-PET detectors with LuAG, GAGG and L(Y)SO scintillators of various sizes coupled to FBK-SiPMs. Journal of Instrumentation, 11(08), P08008-P08008. doi:10.1088/1748-0221/11/08/p0800

Exploring TOF Capabilities of PET Detector Blocks Based on Large Monolithic Crystals and Analog SiPMs

[EN] Monolithic scintillators are more frequently used in PET instrumentation due to their advantages in terms of accurate position estimation of the impinging gamma rays both planar and depth of interaction, their increased efficiency, and expected timing capabilities. Such timing performance has been studied when those blocks are coupled to digital photosensors showing an excellent timing resolution. In this work we study the timing behaviour of detectors composed by monolithic crystals and analog SiPMs read out by an ASIC. The scintillation light spreads across the crystal towards the photosensors, resulting in a high number of SiPMs and ASIC channels fired. This has been studied in relation with the Coincidence Timing Resolution (CTR). We have used LYSO monolithic blocks with dimensions of 50 x 50 x 15 mm(3) coupled to SiPM arrays (8 x 8 elements with 6 x 6 mm(2) area) which compose detectors suitable for clinical applications. While a CTR as good as 186 ps FWHM was achieved for a pair of 3 x 3 x 5 mm(3) LYSO crystals, when using the monolithic block and the SiPM arrays, a raw CTR over 1 ns was observed. An optimal timestamp assignment was studied as well as compensation methods for the time-skew and time-walk errors. This work describes all steps followed to improve the CTR. Eventually, an average detector time resolution of 497 ps FWHM was measured for the whole thick monolithic block. This improves to 380 ps FWHM for a central volume of interest near the photosensors. The timing dependency with the photon depth of interaction and planar position are also included.This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No 695536). It has also been supported by the Spanish Ministerio de Economia, Industria y Competitividad under Grant TEC2016-79884-C2-1-R.Lamprou, E.; González Martínez, AJ.; Sánchez Martínez, F.; Benlloch Baviera, JM. (2020). Exploring TOF Capabilities of PET Detector Blocks Based on Large Monolithic Crystals and Analog SiPMs. Physica Medica. 70:10-18. https://doi.org/10.1016/j.ejmp.2019.12.004101870Surti, S. (2014). Update on Time-of-Flight PET Imaging. Journal of Nuclear Medicine, 56(1), 98-105. doi:10.2967/jnumed.114.145029Spanoudaki, V. C., & Levin, C. S. (2010). Photo-Detectors for Time of Flight Positron Emission Tomography (ToF-PET). Sensors, 10(11), 10484-10505. doi:10.3390/s101110484Szczesniak, T., Moszynski, M., Swiderski, L., Nassalski, A., Lavoute, P., & Kapusta, M. (2009). Fast Photomultipliers for TOF PET. IEEE Transactions on Nuclear Science, 56(1), 173-181. doi:10.1109/tns.2008.2008992Renker, D. (2007). New trends on photodetectors. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 571(1-2), 1-6. doi:10.1016/j.nima.2006.10.016Kim, C. L., Wang, G.-C., & Dolinsky, S. (2009). Multi-Pixel Photon Counters for TOF PET Detector and Its Challenges. IEEE Transactions on Nuclear Science, 56(5), 2580-2585. doi:10.1109/tns.2009.2028075Moses, W. W. (2002). Current trends in scintillator detectors and materials. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 487(1-2), 123-128. doi:10.1016/s0168-9002(02)00955-5Gundacker, S., Auffray, E., Pauwels, K., & Lecoq, P. (2016). Measurement of intrinsic rise times for various L(Y)SO and LuAG scintillators with a general study of prompt photons to achieve 10 ps in TOF-PET. Physics in Medicine and Biology, 61(7), 2802-2837. doi:10.1088/0031-9155/61/7/2802Gundacker, S., Acerbi, F., Auffray, E., Ferri, A., Gola, A., Nemallapudi, M. V., … Lecoq, P. (2016). State of the art timing in TOF-PET detectors with LuAG, GAGG and L(Y)SO scintillators of various sizes coupled to FBK-SiPMs. Journal of Instrumentation, 11(08), P08008-P08008. doi:10.1088/1748-0221/11/08/p08008Surti, S., & Karp, J. S. (2016). Advances in time-of-flight PET. Physica Medica, 32(1), 12-22. doi:10.1016/j.ejmp.2015.12.007Gundacker, S., Knapitsch, A., Auffray, E., Jarron, P., Meyer, T., & Lecoq, P. (2014). Time resolution deterioration with increasing crystal length in a TOF-PET system. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 737, 92-100. doi:10.1016/j.nima.2013.11.025Marcinkowski, R., España, S., Van Holen, R., & Vandenberghe, S. (2014). Optimized light sharing for high-resolution TOF PET detector based on digital silicon photomultipliers. Physics in Medicine and Biology, 59(23), 7125-7139. doi:10.1088/0031-9155/59/23/7125González-Montoro, A., Sánchez, F., Martí, R., Hernández, L., Aguilar, A., Barberá, J., … González, A. J. (2018). Detector block performance based on a monolithic LYSO crystal using a novel signal multiplexing method. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 912, 372-377. doi:10.1016/j.nima.2017.10.098Xi, D., Xie, Q., Zhu, J., Lin, L., Niu, M., Xiao, P., … Kao, C.-M. (2012). Optimization of the SiPM Pixel Size for a Monolithic PET Detector. Physics Procedia, 37, 1497-1503. doi:10.1016/j.phpro.2012.04.101Gonzalez-Montoro A, Aguilar A, Canizares G, Conde P, Hernandez L, Vidal LF, et al. Performance Study of a Large Monolithic LYSO PET Detector With Accurate Photon DOI Using Retroreflector Layers. IEEE Trans Rad Plasma Med Sci. PP. 1-1. DOI: 10.1109/TRPMS.2017.2692819.Krishnamoorthy, S., Blankemeyer, E., Mollet, P., Surti, S., Van Holen, R., & Karp, J. S. (2018). Performance evaluation of the MOLECUBES β-CUBE—a high spatial resolution and high sensitivity small animal PET scanner utilizing monolithic LYSO scintillation detectors. Physics in Medicine & Biology, 63(15), 155013. doi:10.1088/1361-6560/aacec3González-Montoro, A., Sánchez, F., Bruyndonckx, P., Cañizares, G., Benlloch, J. M., & González, A. J. (2019). Novel method to measure the intrinsic spatial resolution in PET detectors based on monolithic crystals. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 920, 58-67. doi:10.1016/j.nima.2018.12.056Van Dam, H. T., Borghi, G., Seifert, S., & Schaart, D. R. (2013). Sub-200 ps CRT in monolithic scintillator PET detectors using digital SiPM arrays and maximum likelihood interaction time estimation. Physics in Medicine and Biology, 58(10), 3243-3257. doi:10.1088/0031-9155/58/10/3243Di Francesco A, Bugalho R, Oliveira L, Pacher L, Rivetti A, Rolo M, et al. TOFPET2: A high-performance ASIC for time and amplitude measurements of SiPM signals in time-of-flight applications. Journal of Instrumentation, vol. 11, no. 03, p. C03042.TOFPET2 ASIC Evaluation kit - Hardware User Guide (v1.2), v1.2, PETsys Electronics SA., 2018.Lamprou, E., Aguilar, A., González-Montoro, A., Monzó, J. M., Cañizares, G., Iranzo, S., … Benlloch, J. M. (2018). PET detector block with accurate 4D capabilities. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 912, 132-136. doi:10.1016/j.nima.2017.11.002Acerbi, F., & Gundacker, S. (2019). Understanding and simulating SiPMs. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 926, 16-35. doi:10.1016/j.nima.2018.11.118Schug D, Nadig V, Weissler B, Gebhardt P, Schulz V. Initial Measurements with the PETsys TOFPET2 ASIC Evaluation Kit and a Characterization of the ASIC TDC IEEE Trans Rad Plasma Med Sci. PP. 1-1. DOI: 10.1109/TRPMS.2018.2884564.Seifert, S., van Dam, H. T., Vinke, R., Dendooven, P., Lohner, H., Beekman, F. J., & Schaart, D. R. (2012). A Comprehensive Model to Predict the Timing Resolution of SiPM-Based Scintillation Detectors: Theory and Experimental Validation. IEEE Transactions on Nuclear Science, 59(1), 190-204. doi:10.1109/tns.2011.2179314Vinke R, Olcott PD, Cates JW, Levin CS. The lower timing resolution bound for scintillators with non-negligible optical photon transport time in time-of-flight PET. Phys. Med. Phys. Med. Biol. 59 6215. Phys Med Biol. 2014; 59(20): 6215–29.Gonzalez AJ, Sanchez F, Benlloch JM. 2018 Organ-Dedicated Molecular Imaging Systems. IEEE Trans Ratiat Plasma Med Sci. 2017; 2(5): 388–403

Identification of Tools for the Functional and Subjective Assessment of Patients in an Aquatic Environment: A Systematic Review

Aquatic therapy is one of the most common treatments for alleviating musculoskeletal pathologies. Its effectiveness has been evaluated with functional tests and questionnaires. Functional tests are used in aquatic therapy; however, in most cases, they are carried out in a non-aquatic environment and, as such, their results may differ from those of tests performed in an aquatic environment. A systematic review was performed to assess the accuracy of functional tests and patient-reported outcomes to assess aquatic therapy interventions. The authors conducted a literature search in July 2019. In total, 70,863 records were identified after duplicates removed. Of these, 14 records were included about functional tests assessment in aquatic environment and 725 records for questionnaires. The majority of the tests had also been assessed in a dry environment, allowing differences and similarities between the tests in the two environments to be observed. Different variables have been assessed in tests included in the present systematic review (cardiorespiratory, neuromuscular, kinematic, physiological, kinetic responses and rating of perceived exertion) which are included in the manuscript. Visual Analogue Scale, Western Ontario and McMaster Universities Osteoarthritis Index and the 12-item Short Form Health Survey were the assessments most commonly used by the different authors

Predictive model for polishing times in mould finishing

El pulido, proceso final utilizado en la producción de piezas, es a menudo lento y se aplica manualmente. Normalmente define la rugosidad superficial y la precisión de la pieza. Se lleva a cabo utilizando partículas duras para producir la abrasión de la superficie de la pieza a pulir. En este documento se propone un modelo para predecir el progreso del frente de pulido. El modelo tiene en cuenta la topografía resultante antes de la mecanización a través de su curva de Abbott - Firestone, la velocidad relativa del material abrasivo, la fuerza aplicada, el material de la pieza y el tamaño de los granos abrasivos. Separa las aportaciones realizadas por el material de la pieza y el tipo abrasivo de la topografía previa. También muestra los valores recomendados para los diferentes parámetros de proceso a ser utilizados en la predicción de la evolución del frente de pulido en algunos materiales. Además se estima el tiempo de pulido necesario para eliminar completamente la topografía resultante del fresado utilizando una estrategia de perforación transversal. Por último, se muestra la predicción del modelo del frente de pulido, lo que confirma que el mecanismo de abrasión caracteriza dicho proceso.Polishing, the final process used in the production of parts, is often slow and often applied manually. It normally defines the surface roughness and part accuracy. It is performed using hard particles to produce abrasion of the workpiece surface to be polished. In this paper a model for predicting the progress of the polishing face is proposed. The model considers the topography resulting from prior mechanizing through its Abbott-Firestone curve, the relative speed of the abrasive material, the applied force, the workpiece material and the size of the abrasive grains. It separates the contributions made by the workpiece material and the abrasive type from the prior topography. It also shows recommended values for different process parameters to be used in predicting the evolution of the polishing front in some materials. Additionally, the polishing time required to completely remove the topography that results from ball milling using a cross drilling strategy is estimated. Finally, the model's correct prediction of the polished front is shown, confirming that the abrasion mechanism characterizes the sandpaper polishing process.Peer Reviewe

Bottoming bending process assisted by electroplasticity

Este estudio reporta la influencia de los efectos atérmicos de la electroplasticidad en el proceso de doblado por estampa. Se fabrica un generador que generar pulsos de 300A y un ancho de 50μs. Los materiales estudiados fueron Al1050 y X5CrNi18-10. Se realizó un análisis por elementos finitos para caracterizar las diferentes fases del comportamiento mecánico de las probetas durante el proceso. Se estudió el efecto que tienen los pulsos de corriente sobre las fases mencionadas, prestando especial atención a las de recuperación elástica y la de máxima deformación plástica. Los resultados muestran que en el proceso asistido eléctricamente se reducen las fuerzas de doblado, hasta en un 18% en el aluminio y un 6% en el acero inoxidable. Además se observa que se reduce la recuperación elástica del material en un 21% y un 12% respectivamente. Se concluye que los efectos atérmicos de la electroplasticidad influyen en el proceso estudiado.The present study reports the influence of electroplasticity athermal effects on bottoming bending. To do so a short-time current pulse generator, capable of inducing 300A current pulses and a 50μs pulse duration, was manufactured. The materials studied were Al1050 and X5CrNi18-10. A finite element analysis was done in order to characterize the different phases of specimen mechanical behavior during bottoming bending. The influence of current pulses on different phases was studied, specifically on the elastic restoring force and the maximum plastic deformation phases. The results show that, compared to the conventional process, during the electrically-assisted process bending forces drop up to 18% in aluminium and 6% in stainless steel. The elastic restoring force is also reduced by 21% and 12% respectively. Therefore it can be concluded that the electroplasticity athermal effects have an influence on the bottoming bending process.Peer Reviewe

Enhanced Parallel Sine Cosine Algorithm for Constrained and Unconstrained Optimization

The sine cosine algorithm’s main idea is the sine and cosine-based vacillation outwards or towards the best solution. The first main contribution of this paper proposes an enhanced version of the SCA algorithm called as ESCA algorithm. The supremacy of the proposed algorithm over a set of state-of-the-art algorithms in terms of solution accuracy and convergence speed will be demonstrated by experimental tests. When these algorithms are transferred to the business sector, they must meet time requirements dependent on the industrial process. If these temporal requirements are not met, an efficient solution is to speed them up by designing parallel algorithms. The second major contribution of this work is the design of several parallel algorithms for efficiently exploiting current multicore processor architectures. First, one-level synchronous and asynchronous parallel ESCA algorithms are designed. They have two favors; retain the proposed algorithm’s behavior and provide excellent parallel performance by combining coarse-grained parallelism with fine-grained parallelism. Moreover, the parallel scalability of the proposed algorithms is further improved by employing a two-level parallel strategy. Indeed, the experimental results suggest that the one-level parallel ESCA algorithms reduce the computing time, on average, by 87.4% and 90.8%, respectively, using 12 physical processing cores. The two-level parallel algorithms provide extra reductions of the computing time by 91.4%, 93.1%, and 94.5% with 16, 20, and 24 processing cores, including physical and logical cores. Comparison analysis is carried out on 30 unconstrained benchmark functions and three challenging engineering design problems. The experimental outcomes show that the proposed ESCA algorithm behaves outstandingly well in terms of exploration and exploitation behaviors, local optima avoidance, and convergence speed toward the optimum. The overall performance of the proposed algorithm is statistically validated using three non-parametric statistical tests, namely Friedman, Friedman aligned, and Quade tests.This research was supported by the Spanish Ministry of Science, Innovation and Universities and the Research State Agency under Grant RTI2018-098156-B-C54 cofinanced by FEDER funds and the Ministry of Science and Innovation and the Research State Agency under Grant PID2020-120213RB-I00 cofinanced by FEDER funds

Estimation of the polishing time for different metallic alloys in surface texture removal

The aim of this work is to propose a novel analytical model for predicting the polishing time and behavior of the surface texture removal in different metal alloys. The surface texture, resulting from a previous milling process, is characterized and investigated by the Abbott–Firestone curve, the relative speed of the abrasive material, the applied force, the type of material and the size of the abrasive grains. Consequently, a model that predicts the surface texture evolution based on the mechanism of abrasion is proposed, in which a constant of the wear model is found to behave linearly with the size of the abrasive grain for each metal alloy. Based on the good agreement between the experimental and the estimated values (R2 equal to 0.993), operational parameters are recommended to predict the required surface texture for AlCu4PbMg, 30CrNiMo8, C45E and X6CrNiMo8 when using abrasive grade between P180 and P1200.Peer ReviewedPreprin