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Digital Inverse Model Control Using Generalised Holds With Extensions to the Adaptive Case
Asier Ibeas,Pedro Balaguer,Carles Pedret,Manuel de la Sen 제어·로봇·시스템학회 2010 International Journal of Control, Automation, and Vol.8 No.4
In this paper, a digital implementation of an inverse-model based control scheme is proposed using Generalised Sampling and Hold Functions. The implementation of the controller using this kind of holds allows overcoming the difficulties related to the presence of unstable zeros in the continuous-time model and the usual appearance of unstable discretisation zeros in the discrete model when a ZOH is applied. The Generalised Sampling and Hold Functions allows obtaining a discrete model of the plant with all its zeros stable which allows realizing an exact inverse model of the plant in comparison to the use of a classical ZOH which only allows, in general, an approximate inversion of the plant. The proposed approach is then extended to the adaptive case where the stability and tracking properties of the general scheme are fully proved. Simulation examples showing the scope and application of the method are also presented.
Data-mining modeling for the prediction of wear on forming-taps in the threading of steel components
Bustillo, Andres,Lopez de Lacalle, Luis N.,Fernandez-Valdivielso, Asier,Santos, Pedro Society for Computational Design and Engineering 2016 Journal of computational design and engineering Vol.3 No.4
An experimental approach is presented for the measurement of wear that is common in the threading of cold-forged steel. In this work, the first objective is to measure wear on various types of roll taps manufactured to tapping holes in microalloyed HR45 steel. Different geometries and levels of wear are tested and measured. Taking their geometry as the critical factor, the types of forming tap with the least wear and the best performance are identified. Abrasive wear was observed on the forming lobes. A higher number of lobes in the chamber zone and around the nominal diameter meant a more uniform load distribution and a more gradual forming process. A second objective is to identify the most accurate data-mining technique for the prediction of form-tap wear. Different data-mining techniques are tested to select the most accurate one: from standard versions such as Multilayer Perceptrons, Support Vector Machines and Regression Trees to the most recent ones such as Rotation Forest ensembles and Iterated Bagging ensembles. The best results were obtained with ensembles of Rotation Forest with unpruned Regression Trees as base regressors that reduced the RMS error of the best-tested baseline technique for the lower length output by 33%, and Additive Regression with unpruned M5P as base regressors that reduced the RMS errors of the linear fit for the upper and total lengths by 25% and 39%, respectively. However, the lower length was statistically more difficult to model in Additive Regression than in Rotation Forest. Rotation Forest with unpruned Regression Trees as base regressors therefore appeared to be the most suitable regressor for the modeling of this industrial problem.
Murat Kaya,Lalehan Akyuz,Idris Sargin,Muhammad Mujtaba,Asier M. Salaberria,Jalel Labidi,Yavuz S. Cakmak,Behlul Koc,Talat Baran,Talip Ceter 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.47 No.-
Sporopollenin-chitosan blendfilms were produced for thefirst time. Sporopollenin is a robust structuralcomponent of plant pollens exhibiting excellent features such as nontoxicity, biodegradability,biocompatibility, high thermal stability, durability to strong acid and base solutions and homogeneityin size. To benefit from these advantages, sporopollenin samples obtained from Betula pendula (silverbirch) were incorporated into chitosanfilm at different concentration; 10, 20 and 40 mg in 100 mLchitosan gel (1%). Stereo microscopy, FT-IR and TG/DTG analyses showed that sporopollenin wassuccessfully incorporated into the chitosan matrix. Incorporation of sporopollenin in gradually increasingamount into chitosanfilms was found advantageous in (1) enhancement in chemical durability of thefilms, (2) increment of hydrophobicity, (3) boosting the mechanical properties, (4) improvement ofantifungal and (5) antioxidant activities. This study revealed that sporopollenin can be suggested as aneffective blend material for biodegradable edible chitosanfilm production.
Simulation of Cryo-cooling to Improve Super Alloys Cutting Tools
Octavio Pereira,Adrián Rodríguez,Amaia Calleja-Ochoa,Ainhoa Celaya,Luis Norberto López de Lacalle,Asier Fernández-Valdivielso,Haizea González 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.1
Improve machining processes from an environmental point of view is a hot topic currently. In this line, cryogenics CO 2 is presented as a solution to substitute conventional oil emulsions. However, to be applied industrially, it is needed to control CO 2 flow rate with the aim of reducing CO 2 consumption to reach what it is known as ECO 2 -performance (economy + ecology). Then, despite currently CO 2 cooling technique is used as external coolant, it is needed to improve its use—especially in milling processes—for achieving this goal. In line with this, in this paper is presented the use of CO 2 as tool internal coolant as a solution to optimize its use. For checking its suitability, a study based on computer fluid dynamics with a new cryogenic tool channels design and experimental tests were carried out for analyzing the differences between using CO 2 as internal and external coolant with the aim of improving the use of cryogenic gases during Inconel 718 milling processes. The results show that the use of CO 2 as internal coolant improves the current milling process not only from environmental point of view but also economic and technical, bringing CO 2 cryogenic technology closer to industrial milling conditions.
Rodríguez-Gómez Irene,Sánchez-Martín Coral,García-García Francisco J.,García-Esquinas Esther,Miret Marta,Vicente-Rodriguez Germán,Gusi Narcís,Mañas Asier,Carnicero José A.,Gonzalez-Gross Marcela,Ayuso 한국역학회 2022 Epidemiology and Health Vol.44 No.-
OBJECTIVES: This study investigated the associations of chronic diseases with changes in lifestyle and health behaviours in older people following the coronavirus disease 2019 (COVID-19) lockdown in Spain and compared the differences in changes over time. METHODS: 1,092 participants (80.3± 5.6 years; 66.5% female) from 2 Spanish cohorts were included. Telephone-based questionnaires were conducted to evaluate lifestyle and health risk behaviours at the end of lockdown and 7 months post-lockdown. Participants were classified as having physician-diagnosed chronic diseases based on self-reported data. Cox proportional models adjusted for major confounders were used. RESULTS: Compared to those without the corresponding chronic diseases, older people with hypertension were less likely to report increased alcohol consumption (hazard ratio [HR], 0.73; 95% confidence interval [CI], 0.55 to 0.99). Pulmonary diseases were associated with lower risks of increased sedentary time (HR, 0.58; 95% CI, 0.39 to 0.86) and worsened sleep quality (HR, 0.56; 95% CI, 0.36 to 0.87), while cardiovascular diseases were associated with a lower risk of decreased sedentary time (HR, 0.58; 95% CI, 0.38 to 0.88). Depression was linked to a higher likelihood of improved diet quality (HR, 1.53; 95% CI, 1.00 to 2.36). Cancer pacients were less likely to have worsened sleep quality (HR, 0.44; 95% CI, 0.22 to 0.89) but more likely to have reduced their frequency of social contact (HR, 2.05; 95% CI, 1.05 to 3.99). CONCLUSIONS: Older people with chronic diseases showed beneficial changes in lifestyle and health risk behaviours after the COVID-19 lockdown. In particular, older people with hypertension, pulmonary disease, and cancer tended to make beneficial lifestyle and health behaviour changes. However, older people with cardiovascular disease and depression engaged in more health risk behaviours.