Efficiency optimization of the push-belt CVT by variator slip control

Continuously Variable Transmissions (CVT) are becoming increasingly popular in automotive applications. What makes them attractive is the ability to vary the transmission ratio in a stepless manner without interrupting the torque transfer. This increases comfort by eliminating the discrete shifting events and increases performance by choosing the most suitable transmission ratio for every driving situation. Using a CVT could potentially save more than 15% of fuel consumption compared to manually shifted vehicles. This figure however is never met, because of the internal losses in the CVTs in production today. If the losses in a CVT can be lowered, then the overall fuel economy of a CVT equipped vehicle will be improved with the same amount. With current CVTs ranging around 80% efficiency, an improvement of around 10% is possible compared to currently available CVTs if an optimal actuation and control system is used. This thesis is about the optimization of the control system of the CVT by using slip as the control variable. This is part of a larger project focussing on the entire actuation and control system. Also a CVT with Electro-Mechanically Pulley Actuation (EMPAct) is developed aiming to reduce the power consumption of the CVT actuation system. Combined, these two projects aim to improve the fuel economy of the CK2 transmission from Jatco with 10%. Models for the clamping forces and traction in the variator are compared. The continuous belt model is compared with a pushbelt model. A parameter study shows the influence of the model parameters on the outcome of the models. The output of the models are also compared to measured values. A nonlinear dynamic model for slip in the variator is derived. This model can be linearized in certain operating points. This model can be used for the design of a control system, simulation of slip in the variator or for analysis. Measurement of slip directly is not possible, therefore a good estimation method is needed. Several estimations of slip in the variator are compared. The position measurement of the pulley is used in the measurements shown in this thesis. Measurements on a beltbox testrig are given that clearly show a relation between slip and efficiency and slip and traction. This relation changes as a function of other parameters like speed, ratio, clamping force etc. Estimation of the efficiency potential of the pushbelt variator shows that a potential of between 5% for high torques and 20% for low torques exists. A slip control system is developed to show the possible efficiency improvement. First, a beltbox setup is used to test a simplified slip controlled variator. Ratio changing is not taken into account in this setup. After successful tests with this setup another setup is used that incorporates a Jatco CK2 transmission and an internal combustion engine. This test setup is more realistic, but therefore also more complicated to control. A gain scheduled approach is used to compensate for the slower actuation system. This system is then also applied to a testing vehicle

Animals and Biographies: Integrated Units for Third/Fourth Looped Classes

This handbook was designed for teachers in a third-to-fourth grade looping classroom. The lessons integrate reading and writing, and the second year (fourth grade) builds upon skills and strategies introduced in the first year (third grade). The third grade set of lessons focuses study on animals while the fourth grade set of lessons focuses on biographies. The handbook contains a OLE/Lesson plan matrix, information for teachers before beginning both sets of lessons, twelve third grade lessons, thirteen fourth grade lessons, and extension activities for both animals and biographies. The final section in the handbook is an appendix that contains every worksheet needed to complete the lessons. Current literature and research regarding child development, various organizational structures in classrooms, looping, learning to read versus reading to learn, and the importance of nonfiction in the elementary classroom were reviewed

Slip controller design and implementation in a Continuously Variable Transmission

Continuously Variable Transmissions (CVT) can be used to operate a combustion engine in a more optimal working point. Unfortunately, due to the relatively low efficiency of modern production CVT’s the total efficiency of the driveline is not increased significantly. This low efficiency is mainly caused by losses in the hydraulic actuation system and the variator. Decreasing the clamping forces in the variator greatly improves the efficiency of the CVT. However, lower clamping forces increase the risk of excessive belt slip, which can damage the system. In this paper a method is presented to measure and control slip in a CVT in order to minimize the clamping forces while preventing destructive belt slip. To ensure robustness of the system against torque peaks, a controller is designed with optimal load disturbance response. A synthesis method for robust PI(D)-controller design is used to maximize the integral gain while making sure that the closed loop system remains stable. Experimental results prove the validity of the approach

The Innovation Institute : from creative inquiry through real-world impact at MIT

Thesis (S.M.M.O.T.)--Massachusetts Institute of Technology, Sloan School of Management, Management of Technology Program, 2006.Includes bibliographical references (leaf 108).This document is an exploration into the past, present, and emerging future of MIT from the perspective of a participant-in and observer-of Institute life and learning, and seeks to better understand how creative inquiry at the Institute leads to real-world impact. We explore the Institute's history, mission, and creative ethos. We survey MIT's links to industry, highlight the inner-connections between the triad of research, education and extracurriculars, and explore the rich entrepreneurial ecosystem, how the Institute formally and informally educates and inspires new generations of founders, builders, and leaders. We conclude by observing how distributed initiative, inquiry, and leadership enable organizational reinvention and survey a few of MIT's emergent future frontiers.by Joost Paul Bonsen.S.M.M.O.T

Mosaik-Defizienz des oxidativen mitochondrialen Metabolismus bei Patient:innen mit Vorhofflimmern

Merit zur Bonsen Dissertation Humanmedizin Promoviert am 02.08.2023 Innere Medizin III der Universität zu Köln, Kardiologie Mosaik-Defizienz des oxidativen mitochondrialen Metabolismus bei Patient:innen mit Vorhofflimmer

Findings and Graduation of Sarcoidosis-Related Uveitis: A Single-Center Study

Ocular involvement is present in up to 79% of sarcoid patients. Uveitis is the main ocular manifestation and presents as a chronic intraocular inflammatory condition with potentially detrimental effects on visual acuity and quality of life. This retrospective study was conducted to explore the incidence and characteristics of ocular sarcoidosis in a single tertiary ophthalmology center. Medical records of 84 patients presenting between June 2007 and March 2021 were analyzed. Based on the "International Workshop on Ocular Sarcoidosis" (IWOS) criteria, ocular sarcoidosis was determined as: definite (n = 24; 28.6%), presumed (n = 33; 39.3%), probable (n = 10; 11.9%), and indefinite (n = 17; 20.2%) in our study population. In 43.9% of the definite and presumed cases, the eye was primarily affected. In addition to specific ocular findings, the diagnosis was supported by biopsy (28.6%) and chest x-ray or computer tomography (66.7%). Moreover, an increased soluble interleukin-2 receptor (sIL-2R) expression (76.2%), elevated angiotensin-converting enzyme (ACE) levels (34.8%), and lymphocytopenia (35.1%) were valuable laboratory findings. Co-affected organs were lungs (60.7%), skin (15.5%), and central nervous system (8.3%). Our findings support the prominent role of the eye in the early detection of sarcoidosis. In addition to the IWOS criteria, sIL-2R, in particular, was shown to be relevant in establishing the diagnosis

Communities of practice in academia

Up to now, the relationships among the fundamental notions of communities of practice (CoPs), i.e. knowledge, participation, identity, and artefact development have been based mainly on results from qualitative studies; they are not yet sufficiently based on quantitative evidence. Starting from a literature review, we formulate a quantitative, causal model of CoPs that describes these variables in the context of academic communities, and aim to validate this model in two academic CoPs with a total of N = 208 participants. A cluster analysis classifies the participants into clusters that are in line with the core-periphery structure known from previous qualitative studies. A regression analysis provides evidence for the hypothesized model on the basis of quantitative data. Suggested directions for future research are to focus on factors that determine CoP participants’ contributions to artefact development and on approaches to automated monitoring of virtual CoPs

Kompetenzen erweitern: Weiterbildungen für Hebammen

Die Berner Fachhochschule hat eine Erhebung zum Weiterbildungsbedarf von Hebammen durchgeführt. Besonders beliebt sind Fachkurse und CAS-Studiengänge. Thematisch wünschen sich Hebammen interprofessionelle Notfall- oder Skillstrainings, aber auch eine Vertiefung zur Unterstützung gesundheitserhaltender Prozesse im perinatalen Setting

The Empact CVT: modeling, simulation and experiments

This paper shows the implementation of a simulation model for newelectromechanically actuated metal V-belt type continuously variabletransmission (CVT), referred to as the Empact CVT. An analysis ofthe dynamics of the actuation system and of the driveline shows thatthe eigenfrequencies of the system depend on both the CVT ratio andthe slip in the variator. An accurate variator model is required to incorporateall characteristic dynamics. The implemented variator modelis an explicit formulation of a model which gives an estimation of thetension forces and compression forces in the pushbelt. The simulationmodel also includes slip, shifting losses based on transient variator modelsand friction. Simulations are compared to measurements, showinggood results