Polynomial Approach and Non-linear Analysis for a Traffic Fundamental Diagram

Vehicular traffic can be modelled as a dynamic discrete form. As in many dynamic systems, the parameters modelling traffic can produce a number of different trajectories or orbits, and it is possible to depict different flow situations, including chaotic ones. In this paper, an approach to the wellknown density-flow fundamental diagram is suggested, using an analytical polynomial technique, in which coefficients are taken from significant values acting as the parameters of the traffic model. Depending on the values of these parameters, it can be seen how the traffic flow changes from stable endpoints to chaotic trajectories, with proper analysis in their stability features

A chemical representation of a chaotic system with a unique stable equilibrium point

"In this paper we present a chemical representation of a chaotic system with only one stable equilibrium point. The approach invokes cooperative catalysis and slow-fast reactions, primarily. The obtained chemical based chaotic dynamical system preserves the eigenvalues of the unique and stable equilibrium point along with the Lyapunov’s dimension and exponents of the original one.

Performance analysis of a PID fractional order control in a differential mobile robot

[EN] This work deals with the tracking trajectory problem for a differential-drive mobile robot taking into account a dynamic extension from the kinematic model and, controlling a front point located at a certain distance perpendicular to the mid-axis of the wheels. Two controls are proposed, a PID fractional order controller (PIδDµ) and a PD fractional order controller (PDµ), both based on the tracking errors. The proposed controllers are obtained by means of the input-output linearization technique. On the other hand, the controller fractional terms are based on the Caputo’s operator. Numerical simulations with different fractional orders are presented and compared with the integer order PID controller, showing the variations that occurred when changing only the controller order.[ES] Este trabajo aborda el problema de seguimiento de trayectorias de un robot móvil tipo diferencial considerando una extensión dinámica del modelo cinemático y, controlando un punto frontal situado a una cierta distancia perpendicular al eje medio de las ruedas. Se proponen dos tipos de controladores, un controlador PID de orden fraccionario (PIdeltaDmu) y un controlador PD fraccionario (PDmu), ambos basados en errores de seguimiento. Los controladores propuestos se obtienen empleando la técnica de linealización entrada-salida. Por otra parte, los términos fraccionarios del controlador se basan en el operador de Caputo. Se presentan simulaciones numéricas con diferentes órdenes fraccionarios y se comparan con el controlador PID de orden entero, mostrando las variaciones ocurridas al cambiar únicamente el orden del controlador.División de Investigación y Posgrado (DINVP) de la Universidad IberoamericanaVázquez, U.; González-Sierra, J.; Fernández-Anaya, G.; Hernández-Martínez, EG. (2021). Análisis del desempeño de un control PID de orden fraccional en un robot móvil diferencial. Revista Iberoamericana de Automática e Informática industrial. 19(1):74-83. https://doi.org/10.4995/riai.2021.15036OJS7483191Al-Mayyahi, A., Wang, W., Birch, P., 2016. Design of fractional-order controller for trajectory tracking control of a non-holonomic autonomous ground vehicle. Journal of Control, Automation and Electrical Systems 27 (1), 29-42. https://doi.org/10.1007/s40313-015-0214-2Betourne, A., Campion, G., 1996. Dynamic modelling and control design of a class of omnidirectional mobile robots. In Proceedings of IEEE International Conference on Robotics and Automation 3, 2810-2815.Buslowicz, M., 2012. Stability analysis of continuous-time linear systems consisting of n subsystems with different fractional orders. Bulletin of the Polish Academy of Sciences. Technical Sciences 60 (2), 279-284. https://doi.org/10.2478/v10175-012-0037-2Buslowicz, M., 2013. Frequency domain method for stability analysis of linear continuous-time state-space systems with double fractional orders. In Advances in the Theory and Applications of Non-integer Order Systems, Springer, Heidelberg, 31-39. https://doi.org/10.1007/978-3-319-00933-9_3Campion, G., Bastin, G., Dandrea-Novel, B., 1996. Structural properties and classification of kinematic and dynamic models of wheeled mobile robots. IEEE transactions on robotics and automation 12 (1), 47-62. https://doi.org/10.1109/70.481750Contreras, J., Herrera, D., Toibero, J., Carelli, R., 2017. Controllers design for differential drive mobile robots based on extended kinematic modeling. In 2017 European Conference on Mobile Robots, 1-6.Fierro, R., Lewis, F., 1998. Control of a nonholonomic mobile robot using neural networks. IEEE transactions on neural networks 9 (4), 589-600. https://doi.org/10.1109/72.701173Kanjanawanishkul, K., Zell, A., 2009. Path following for an omnidirectional mobile robot based on model predictive control. In 2009 IEEE International Conference on Robotics and Automation, 3341-3346. https://doi.org/10.1109/ROBOT.2009.5152217Khalil, H., Grizzle, J., 2002. Nonlinear systems. Upper Saddle River, NJ: Prentice hall 3.Martínez, E., Ríos, H., Mera, M., Gonzalez-Sierra, J., 2019. A robust tracking control for unicycle mobile robots: An attractive ellipsoid approach. In 2019 IEEE 58th Conference on Decision and Control (CDC), 5799-5804. https://doi.org/10.1109/CDC40024.2019.9029954Matignon, D., 1996. Stability results for fractional differential equations with applications to control processing. In IMACS Multiconference on Computational engineering in systems applications 2 (1), 963-968.Matignon, D., 1998. Stability properties for generalized fractional differential systems. In ESAIM: Proceedings 5, 145-158. https://doi.org/10.1051/proc:1998004Miller, K., Ross, B., 1993. An introduction to the fractional calculus and fractional differential equations.Orman, K., Basci, A., Derdiyok, A., 2016. Speed and direction angle control of four wheel drive skid-steered mobile robot by using fractional order pi controller. Elektronika ir Elektrotechnika 22 (5), 14-19. https://doi.org/10.5755/j01.eie.22.5.16337Ovalle, L., Ríos, H., Llama, M., Dzul, V. S. A., 2019. Omnidirectional mobile robot robust tracking: Sliding-mode output-based control approaches. Control Engineering Practice 85, 50-58. https://doi.org/10.1016/j.conengprac.2019.01.002Park, B., Yoo, S., Park, J., Choi, Y., 2008. Adaptive neural sliding mode control of nonholonomic wheeled mobile robots with model uncertainty. IEEE Transactions on Control Systems Technology 17 (1), 207-214. https://doi.org/10.1109/TCST.2008.922584Petrás, I., 2008. Stability of fractional-order systems with rational orders. Fractional Calculus and Applied Sciences 10.Petrás, I., 2011. Fractional-order nonlinear systems: Modeling, analysis and simulation. Nonlinear Physical Science Book Series, Springer. https://doi.org/10.1007/978-3-642-18101-6Petrás, I., Dorcák, L., 1999. The frequency method for stability investigation of fractional control systems. J. of SACTA 2 (1-2), 75-85.Podlubny, I., 1998. Fractional differential equations: an introduction to fractional derivatives, fractional differential equations, to methods of their solution and some of their applications. Elsevier, 340.Radwan, A., Soliman, A., Elwakil, A., Sedeek, A., 2009. On the stability of linear systems with fractional-order elements. Chaos, Solitons & Fractals 40 (5), 2317-2328. https://doi.org/10.1016/j.chaos.2007.10.033Rasheed, L., Al-Araji, A., 2017. A cognitive nonlinear fractional order pid neural controller design for wheeled mobile robot based on bacterial foraging optimization algorithm. Engineering and Technology Journal 35 (3), 289-300.Rodriguez-Cortes, H., Aranda-Bricaire, E., 2007. Observer based trajectory tracking for a wheeled mobile robot. In 2007 American Conference Control, 991-996. https://doi.org/10.1109/ACC.2007.4282706Rojas-Moreno, A., Perez-Valenzuela, G., 2017. Fractional order tracking control of a wheeled mobile robot. IEEE XXIV International Conference on Electronics, Electrical Engineering and Computing, 1-4. https://doi.org/10.1109/INTERCON.2017.8079683Sabatier, J., Moze, M., Farges, C., 2010. Lmi stability conditions for fractional order systems. Computers & Mathematics with Applications 59 (5), 1594-1609. https://doi.org/10.1016/j.camwa.2009.08.003Siegwart, R., Nourbakhsh, I., Scaramuzza, D., 2011. Introduction to autonomous mobile robots. MIT press.Sira-Ramírez, H., López-Uribe, C., Velasco-Villa, M., 2013. Linear observer-based active disturbance rejection control of the omnidirectional mobile robot. Asian Journal of Control 15 (1), 51-63. https://doi.org/10.1002/asjc.523Tawfik, M., Abdulwahb, E., Swadi, S., 2014. Trajectory tracking control for a wheeled mobile robot using fractional order piadb controller. Al-Khwarizmi Engineering Journal 10 (3), 39-52.Tepljakov, A., 2017. Fractional-order modeling and control of dynamic systems; fomcon: Fractional-order modeling and control toolbox. Springer Theses, 107--129. https://doi.org/10.1007/978-3-319-52950-9Tepljakov, A., Petlenkov, E., Belikov, J., Finajev, J., 2013. Fractional-order controller design and digital implementation using fomcon toolbox for matlab. IEEE Conference on Computer Aided Control System Design, 340--345. https://doi.org/10.1109/CACSD.2013.6663486Valerio, D., Costa, J. D., 2013. An introduction to fractional control. IET 91, 32-208.Vázquez, J., Velasco-Villa, M., 2008. Path-tracking dynamic model based control of an omnidirectional mobile robot. IFAC Proceedings Volumes 41 (2), 5365-5370. https://doi.org/10.3182/20080706-5-KR-1001.00904Yang, H., Fan, X., Shi, P., Hua, C., 2015. Nonlinear control for tracking and obstacle avoidance of a wheeled mobile robot with nonholonomic constraint. IEEE Transactions on Control Systems Technology 24 (2), 741-746. https://doi.org/10.1109/TCST.2015.2457877Zhang, L., Liu, L., Zhang, S., 2020. Design, implementation, and validation of robust fractional-order pd controller for wheeled mobile robot trajectory tracking. Complexity 2020, 1-12. https://doi.org/10.1155/2020/9523549Zhao, Y., Chen, N., Tai, Y., 2016. Trajectory tracking control of wheeled mobile robot based on fractional order backstepping. In 2016 Chinese Control and Decision Conference, 6730-6734. https://doi.org/10.1109/CCDC.2016.753220

A General Solution for Troesch's Problem

The homotopy perturbation method (HPM) is employed to obtain an approximate solution for the nonlinear differential equation which describes Troesch’s problem. In contrast to other reported solutions obtained by using variational iteration method, decomposition method approximation, homotopy analysis method, Laplace transform decomposition method, and HPM method, the proposed solution shows the highest degree of accuracy in the results for a remarkable wide range of values of Troesch’s parameter

Biobanco de Órganos Dentales de la Facultad de Odontología, Universidad de El Salvador

Objective: to publish a manuscript on the creation of the Biobank of Dental Organs of the Faculty of Dentistry, Universidad de El Salvador. This is a nonprofit entity. It has been created from donations and contains a collection of teeth duly classified, stored, labeled and catalogued. The objective of the biobank is to provide students, professors and researchers with dental organs that comply with standardized protocols, with ethical, legal and biosafety specifications to reduce and/or eliminate the illegal trade of organs. This will present benefits to academic activities and research projects. Materials and methods: the manuscript corresponds to the design of a bibliographic review. A search was carried out in biomedical databases and institutional repositories. In total, 32 scientific articles, 7 academic programs of the undergraduate program in Dental Surgery of the FOUES, 3 national health standards and the National Policy on Ethics and Legality for the Creation of the biobank were included. Results: The BBOD was created as a special academic project, attached to the FOUES Research Center. It is governed by national and international ethical, legal and biosafety standards. At the same time, it is governed by internal protocols for the correct operation, maintenance and conservation of the biological samples storedObjetivo: publicar manuscrito de creación del Biobanco de Órganos Dentales de la Facultad de Odontología, Universidad de El Salvador, una entidad sin fines de lucro que contiene, a partir de donaciones, una colección de dientes debidamente clasificados, almacenados, etiquetados y catalogados. El objetivo del biobanco es proporcionar a estudiantes, profesores e investigadores órganos dentales que cumplan protocolos estandarizados, especificaciones éticas, legales y de bioseguridad para disminuir y/o eliminar el comercio ilegal de órganos, beneficiando de esta manera las actividades académicas y proyectos de investigación. Materiales y métodos: el manuscrito corresponde al diseño de una revisión bibliográfica, se realizó una búsqueda en bases de datos biomédicas y repositorios institucionales, se incluyeron 32 artículos científicos, 7 programas académicos del pregrado en Cirugía Dental de la FOUES, 3 normas sanitarias nacionales y la Política Nacional sobre Ética y Legalidad para la Creación del biobanco. Resultados: creación del BBOD como proyecto académico especial, adscrito al Centro de Investigación de la FOUES, regido bajo las normas éticas, legales y de bioseguridad nacionales e internacionales, por protocolos internos para el correcto funcionamiento, mantenimiento y conservación de las muestras biológicas resguardadas. Conclusión: el biobanco es un centro regido bajo normas éticas, legales y de bioseguridad nacionales e internacionales y por protocolos internos para el funcionamiento, mantenimiento y conservación de las muestras biológicas, con el propósito principal de proveer órganos dentales para fines académicos y de investigación

Impact of treatment and clinical characteristics on the survival of children with medulloblastoma in Mexico

IntroductionData on medulloblastoma outcomes and experiences in low- and middle-income countries, especially in Latin America, is limited. This study examines challenges in Mexico’s healthcare system, focusing on assessing outcomes for children with medulloblastoma in a tertiary care setting.MethodsA retrospective analysis was conducted, involving 284 patients treated at 21 pediatric oncology centers in Mexico.ResultsHigh-risk patients exhibited markedly lower event-free survival than standard-risk patients (43.5% vs. 78.3%, p<0.001). Influential factors on survival included anaplastic subtype (HR 2.4, p=0.003), metastatic disease (HR 1.9, p=0.001); residual tumor >1.5cm², and lower radiotherapy doses significantly impacted event-free survival (EFS) and overall survival (OS). Platinum-based chemotherapy showed better results compared to the ICE protocol in terms of OS and EFS, which was associated with higher toxicity. Patients under 3 years old displayed notably lower OS and EFS compared to older children (36.1% vs. 55.9%, p=0.01)

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries