Ein Beitrag zur Potenzialanalyse von reifenfülldruckbasierten Fahrerassistenzsystemen

Bei der Wahl des optimalen Reifenfülldrucks besteht ein sehr großes Spannungsfeld zwischen sich gegenüberstehenden Komfort-, Sicherheits- und Umweltanforderungen. Eine intelligent geregelte Reifenfülldruckregelanlage (RDRA), die den Reifeninnendruck hochdynamisch und radselektiv in Abhängigkeit des Fahrzeug- und Fahrbahnzustands adaptiert, verspricht ein großes Potenzial zur Minimierung der Zielkonflikte. Im Rahmen dieser Forschungsarbeit wird eine Methodik zur Realisierung und Bewertung der Leistungsfähigkeit eines reifenfülldruckbasierten Fahrerassistenzsystems erarbeitet. Die Entwicklung eines Reifenmessanhängers sowie eines Corner-Modul-Prüfstands als mobile bzw. stationäre Prüfeinrichtung zur Charakterisierung von Reifeneigenschaften unter Real- bzw. Laborbedingungen sowie die Erarbeitung einer Mess- und Auswertemethode erlauben die Untersuchung des Kraftschlussverhaltens von Reifen. Neben der Bewertung verschiedener Einflussgrößen quantifizieren die analysierten Messergebnisse erstmals den Einfluss großer Reifenfülldruckvariationen auf das Umfangskraftverhalten von Pkw-Reifen. Da die Reifencharakteristiken, die im Labor auf Prüfstandstrommeln sowie auf realer Asphaltfahrbahn erfasst wurden, teilweise voneinander abweichen, wird eine Umrechnungsmethode erarbeitet, die den Fahrbahnkrümmungseinfluss berücksichtigt. Das Verfahren erlaubt es, Umfangskraftbeiwert-Schlupf-Kennlinien anhand von Reifenlatschmessungen zu skalieren. Schließlich wird die allgemeingültige Anwendbarkeit des Umrechnungsverfahrens sowie der Einfluss der Fahrbahnbeschaffenheit auf das bestimmte Kraftschlussverhalten diskutiert. Der Reifen ist das einzige Bindeglied zwischen dem Kraftfahrzeug und der Fahrbahn. Für numerische Analysen ist die Wahl geeigneter Reifenmodelle sowie die Gewährleistung geringer Approximationsfehler daher unabdingbar. Zur Abbildung des Reifenverhaltens werden die für Fahrdynamiksimulationen besonders relevanten Magic Formula-, HSRI- und Deur-Reifenmodelle für große Reifenfülldruckvariationen erweitert. Eine entwickelte Parametrisierungsmethode erlaubt es, die Koeffizienten der Modelle anhand der Messdaten zu identifizieren. Mit den im Rahmen der hier vorliegenden Forschungsarbeit eingeführten Modellerweiterungen wird erstmals die Möglichkeit geschaffen, mit den genannten Reifensimulationsmodellen große Reifenfülldruckvariationen zu berücksichtigen. Ein entwickeltes Gesamtfahrzeug-Co-Simulationsmodell zur numerischen Berechnung des Fahrdynamikverhaltens von Kraftfahrzeugen erlaubt, neben der Implementierung der erweiterten Reifenmodellgleichungen, die Integration eines parametrisierten Radschlupfregelsystems sowie einer erarbeiteten Reifenfülldruckregelanlage als MIL-Modelle. Der interdisziplinäre und ganzheitliche Simulationsansatz bietet erstmals die Möglichkeit, den Einfluss einer radselektiven, hochdynamischen Reifenfülldruckadaption auf die Fahrdynamik von Kraftfahrzeugen zu bewerten. Der Einfluss verschiedener Parametervariationen sowie die Analyse unterschiedlicher Regelphilosophien auf das im Fokus der Forschung stehende Bremswegverkürzungspotenzial wird dargestellt. Die Resultate erlauben die Schlussfolgerung, dass mithilfe einer gezielten Reifenfülldruckadaption der Bremsweg signifikant verringert werden kann. Schließlich werden die Komponenten einer Reifenfülldruckverstellanlage ausgelegt und, zusammen mit einer entwickelten Regelstrategie, in einem Demonstratorfahrzeug implementiert. Damit wird erstmals eine hochdynamische Reifenfülldruckregelanlage in einem Versuchsfahrzeug realisiert und die Möglichkeit geschaffen, das Potenzial einer intelligent geregelten, hochdynamischen Reifenfülldruckregelanlage als Fahrerassistenzsystem experimentell zu bewerten. Durch umfangreiche Fahrversuche auf einem Testgelände wird das Gesamtfahrzeug-Co-Simulationsmodell validiert. Ein Vergleich numerisch berechneter und experimentell analysierter Bremsweguntersuchungen erlaubt es, die Leistungsfähigkeit der erweiterten Reifenmodelle zur Simulation des Bremswegverkürzungspotenzials durch eine Reifeninnendruckadaption zu bewerten. Nicht zuletzt durch die Analyse des Kraftübertragungsverhaltens im Reifen-Fahrbahn-Kontakt mithilfe eines Radkraftsensors wird das Wirkprinzip eines reifenfülldruckbasierten Fahrerassistenzsystems nachgewiesen. Mit der vorliegenden Forschungsarbeit wird ein Beitrag zur simulativen und experimentellen Bewertung des Potenzials, insbesondere zur Bremswegverkürzung, eines reifenfülldruckbasierten Fahrerassistenzsystems geleistet.Since the tyre inflation pressure has a significant influence on comfort, safety and environmental behaviour, the choice of the optimal inflation pressure is always a conflict of aims. An intelligent controlled Tire Pressure Control System (TPCS), that adapts the inflation pressure highly dynamic and wheel-selective according to the vehicle and road conditions, promises a high potential to minimize this conflict of aims. With this work a methodology to realise and to evaluate the performance of a tyre inflation pressure based driver-assistance system was developed. The development of a Tyre Test Trailer and a Corner Module Test Rig as a mobile, respectively stationary, testing device to acquire tyre characteristics under real, respectively laboratory, conditions as well as the development of a measurement and evaluation method allow to investigate the traction characteristics of tyres. In addition to the evaluation of different influencing parameters, the analysed measurement results quantify the influence of large inflation pressure variations on tangential force behaviour of passenger car tyres for the first time. Since the tyre characteristics, acquired in the laboratory on the drums as well as on a real asphalt road, deviate occasionally, a conversion method to consider the track surface curvature was developed. The procedure allows to scale tangential force-slip-characteristics according to tyre footprint measurements. Eventually, the universal application of the conversion method and the influence of the track surface texture on the traction behaviour were discussed. The tyre is the single connection between the vehicle and the road. Consequently, the choice of appropriate tyre simulation models as well as the guarantee of small approximation errors are essential for numerical analyses. To describe the tyre behaviour, the for vehicle dynamics simulations especially relevant Magic Formula, HSRI and Deur tyre models were extended for large inflation pressure changes. A developed parametrisation method allows to identify the model coefficients by the measured data. With the introduced model extensions a possibility to consider large tyre inflation pressure changes is presented for the first time. A created complete vehicle co-simulation model to calculate the driving dynamics of vehicles allows, in addition to the implementation of the extended tyre model equations, the integration of a parametrised anti-lock braking system and a developed Tire Pressure Control System as MIL models. The interdisciplinary and integrated simulation approach offers initially the possibility to evaluate the influence of a wheelselective, highly dynamic inflation pressure adaptation on vehicle dynamics. The influence of different parameter variations as well as the analysis of different control strategies on the potential of increasing braking performance, which is a focus of this research work, were described. The results lead to the conclusion, that a specific adaptation of the tyre inflation pressure can reduce the stopping distance significantly. Subsequently, the components of a Tire Pressure Control System were designed and, together with a developed control strategy, implemented to a demonstrator vehicle. For the first time a test vehicle with a highly dynamic Tire Pressure Control System was realised. Thereby a facility was created to evaluate experimentally the potential of an intelligent controlled, highly dynamic Tire Pressure Control System. On the basis of comprehensive driving tests on a proving ground the complete vehicle co-simulation model was validated. A comparison of numerically calculated and experimentally determined braking manoeuvres allowed to evaluate the performance of the enhanced tyre models to simulate the potential to reduce the stopping distance by adapting the inflation pressure. Not least because of the analysis of the grip performance in the tyre-road-contact with a wheel force transducer, the operating principle of a tyre inflation pressure based driver-assistance system was proved. The presented work provides a substantial contribution to evaluate the potential of a tyre inflation pressure based driver-assistance system, especially for reducing the stopping distance.Bei der Wahl des optimalen Reifenfülldrucks besteht ein großes Spannungsfeld zwischen sich gegenüberstehenden Komfort-, Sicherheits- und Umweltanforderungen. Eine intelligent geregelte Reifenfülldruckregelanlage, die den Reifeninnendruck hochdynamisch und radselektiv in Abhängigkeit des Fahrzeug- und Fahrbahnzustands adaptiert, verspricht ein großes Potenzial zur Minimierung der Zielkonflikte. In dieser Forschungsarbeit wird eine Methodik zur Realisierung und Bewertung der Leistungsfähigkeit eines reifenfülldruckbasierten Fahrerassistenzsystems vorgestellt. Die Entwicklung von Prüfeinrichtungen sowie einer Mess- und Auswertemethode erlauben die Charakterisierung großer Reifenfülldruckvariationen auf das Umfangskraftverhalten von Pkw-Reifen. Zur Abbildung werden die Magic Formula-, HSRI - und Deur-Reifenmodelle erweitert und in ein entwickeltes Gesamtfahrzeug-Co-Simulationsmodell implementiert. Damit wird erstmals die Möglichkeit geschaffen, große Fülldruckvariationen zu berücksichtigen und deren Einfluss auf die Fahrdynamik von Kraftfahrzeugen zu bewerten. Die Integration einer hochdynamischen Reifenfülldruckregelanlage in einem Versuchsfahrzeug ermöglicht erstmalig eine experimentelle Analyse des Potenzials

Torque vectoring for electric vehicles with individually controlled motors: state-of-the-art and future developments

This paper deals with the description of current and future vehicle technology related to yaw moment control, anti-lock braking and traction control through the employment of effective torque vectoring strategies for electric vehicles. In particular, the adoption of individually controlled electric powertrains with the aim of tuning the vehicle dynamic characteristics in steady-state and transient conditions is discussed. This subject is currently investigated within the European Union (EU) funded Seventh Framework Programme (FP7) consortium E-VECTOORC, focused on the development and experimental testing of novel control strategies. Through a comprehensive literature review, the article outlines the stateof- the-art of torque vectoring control for fully electric vehicles and presents the philosophy and the potential impact of the E-VECTOORC control structure from the viewpoint of torque vectoring for vehicle dynamics enhancement

Extending the HSRI tyre model for large inflation pressure changes

The choice of the optimal tyre inflation pressure is always a conflict of aims since the inflation pressure has a significant influence on safety, comfort and environmental behaviour of a vehicle. The development of a dynamic Tyre Pressure Control System (TPCS) can reduce the conflict of minimal rolling resistance and maximal traction. Driven by the requirements for autonomous driving, recently substantial progress was made to predict the road conditions precisely and robust. This premise moves the development of a Tyre Pressure Control System (TPCS) to the focus of research. To study the influence of the tyre inflation pressure on longitudinal tyre characteristics under laboratory conditions, an experimental sensitivity analysis is performed using a multivalent usable Corner Module Test Rig (CMTR) developed by the Automotive Engineering Group at Technische Universität Ilmenau. The test rig is designed to analyse suspension system and tyre characteristics on a roller of the recently installed 4 chassis roller dynamometer. Camber angle, toe angle and wheel load can be adjusted continuously. In addition, it is possible to control the temperature of the test environment between -20°C and +45°C. The results of the experimental study, that covers a wide range of different wheel loads and inflation pressures for three different tyre variations, show a significant influence of the inflation pressure on longitudinal tyre characteristics as slip stiffness or maximum traction force. To simulate the influence of a TCPS on vehicle dynamics with a numerical simulation tool, it is essential to describe the influence of the inflation pressure on tyre characteristics correctly with a tyre simulation model. Consequently, the well-known physically based HSRI tyre model adapted from Dugoff is extended for large inflation pressure changes. The model parameters for the tyre model are determined with a parameter identification method implemented in a developed automatic MATLAB analysis tool. The extended HSRI tyre model shows a good model accuracy to represent the tyre inflation pressure dependent tyre characteristics

Influenza B vaccine lineage selection--an optimized trivalent vaccine.

Epidemics of seasonal influenza viruses cause considerable morbidity and mortality each year. Various types and subtypes of influenza circulate in humans and evolve continuously such that individuals at risk of serious complications need to be vaccinated annually to keep protection up to date with circulating viruses. The influenza vaccine in most parts of the world is a trivalent vaccine, including an antigenically representative virus of recently circulating influenza A/H3N2, A/H1N1, and influenza B viruses. However, since the 1970s influenza B has split into two antigenically distinct lineages, only one of which is represented in the annual trivalent vaccine at any time. We describe a lineage selection strategy that optimizes protection against influenza B using the standard trivalent vaccine as a potentially cost effective alternative to quadrivalent vaccines.Sera used in this research were kindly provided by the following collaborators: for Australia by Dr. Ian Barr, WHO Collaborating Center, Melbourne, Australia, pediatric sera for the United States by Dr. Jackie Katz, WHO Collaborating Center, Atlanta, US, for Japan by Dr. Takato Odagiri, WHO Collaborating Center, Tokyo, Japan, for China by Dr. Yuelong Shu, WHO Collaborating Center, Beijing, China, for the United Kingdom by Dr. John Wood, NIBSC, Hertfordshire, UK. Additional thanks to Drs Nancy Cox, Michael Shaw, and Alexander Klimov. This work was supported by European Union FP7 program EMPERIE (22349). JMF is supported by a Fellowship in Biomedical Informatics from the Medical Research Council (UK) and a Junior Research Fellowship from Homerton College, Cambridge. Funded by: ERCPMC grant number: FP7 22349.This is the final version of the article. It first appeared from Elsevier via https://doi.org/10.1016/j.vaccine.2016.01.04

PET Quantification Of 18F-Flubatine Binding To Nicotinic alpha4beta2 acetylcholine receptors in Human Brains

Objectives: Nicotinic alpha4beta2 acetylcholine receptors (nAChR) are an important target for diagnostic neuroimaging because of their involvement in Alzheimer's disease (AD) and Parkinson's disease. Using 2-[18F]F-A85380 PET a significant decline in alpha4beta2-nAChRs in early AD-patients which correlated to loss of cognitive function was shown (1, 2). However, this tracer is not suited for use as biomarker for early AD-diagnosis in a routine clinical set-up because of its unfavourable slow kinetics. Here we used the new radiotracer (-)-[18F]-Flubatine (formerly (-)-[18F]-NCFHEB) with significantly improved brain uptake, receptor affinity and selectivity (3). nAChR-parameters were determined by full kinetic modeling and the validity of the practically useful tissue ratio and tissue-to-plasma ratio as receptor parameters was evaluated. Methods: After intravenous administration of ~370 MBq (-)-[18F]-Flubatine, the PET brain imaging was performed in 20 healthy controls (age 70.6±4.6) using an ECAT EXACT HR+ system in 3D-acquisition mode. 23 frames were acquired from 0-90 min post injection and motion corrected with SPM2. Kinetic modeling using a 1-tissue compartment model (1TCM) with arterial input-function was applied to the volume of interest (VOI) based tissue-activity curves (TACs) generated for 29 brain regions (anatomically defined via MRI co-registration). Model-based receptor parameters used were the total distribution volume (VT) and the distribution volume ratio (DVR) (reference: posterior corpus callosum). In addition the standardized uptake value ratio (SUVR) (50-70 min) as approximation of the DVR and the tissue-to-plasma concentration ratio (TTPR) (70-90 min) as approximation of VT were used as non model-based receptor parameters. Results: TACs of all 29 regions could be described adequately with the 1TCM and all kinetic parameters could be reliably estimated from 90 min PET data. VT increased as expected with receptor density. Corpus callosum (VT: 5.68±1.01), frontal cortex (9.18±0.59), parietal cortex (9.10±0.61), pons (11.10±0.86), thalamus (25.03±3.33). Mean TTPR values in frontal and parietal cortices were 2% higher than the corresponding VT values but 7% lower in the thalamus. There was a strong linear correlation between the two sets of TTPR and VT values (r2 = 0.98, p < 10-4) (Fig. 1A). As VT, DVR increased with receptor density. Frontal cortex (DVR: 1.66±0.27), parietal cortex (1.64±0.27), pons (2.01±0.35), thalamus (4.52±0.87). Mean SUVR values in frontal and parietal cortices were almost identical to mean DVR values (difference <0.1%) but ~15 % lower in the thalamus. Accordingly there was a strong linear correlation between the SUVR and DVR values (r2 = 0.97, p < 10-4) (Fig. 1B). Conclusions: For (-)-[18F]-Flubatine the receptor parameters TTPR and SUVR in cortical regions are in excellent agreement with corresponding parameters computed by full kinetic modeling. For unbiased estimates of TTPR and SUVR in the thalamus the use of a bolus/infusion scheme for tracer application should be considered. References: 1. O. Sabri, ..P. Brust: Acetylcholine receptors in dementia and mild cognitive impairment. Eur J Nucl Med Mol Imaging 2008; 35 (Suppl. 1): 30-45. 2. K. Kendziorra, ..O. Sabri: Decreased cerebral a4ß2 nicotinic acetylcholine receptors in living patients with mild cognitive impairment and Alzheimer's disease assessed with positron emission tomography. Eur J Nucl Med Mol Imaging 2010; 38: 515-525. 3. P. Brust, ..O. Sabri: In-vivo measurement of nicotinic acetylcholine receptors with [18 F]norchloro-fluoro-homoepibatidine (NCFHEB). Synapse 2008; 62: 205-218. Linear regression analysis. (A) Tissue-to-plasma concentration ratio (TTPR) and total distribution volume (VT). (B) Standardized uptake value ratio (SUVR) and distribution volume ratio (DVR)

The confounded effects of age and exposure history in response to influenza vaccination.

Numerous studies have explored whether the antibody response to influenza vaccination in elderly adults is as strong as it is in young adults. Results vary, but tend to indicate lower post-vaccination titers (antibody levels) in the elderly, supporting the concept of immunosenescence-the weakening of the immunological response related to age. Because the elderly in such studies typically have been vaccinated against influenza before enrollment, a confounding of effects occurs between age, and previous exposures, as a potential extrinsic reason for immunosenescence. We conducted a four-year study of serial annual immunizations with inactivated trivalent influenza vaccines in 136 young adults (16 to 39 years) and 122 elderly adults (62 to 92 years). Compared to data sets of previously published studies, which were designed to investigate the effect of age, this detailed longitudinal study with multiple vaccinations allowed us to also study the effect of prior vaccination history on the response to a vaccine. In response to the first vaccination, young adults produced higher post-vaccination titers, accounting for pre-vaccination titers, than elderly adults. However, upon subsequent vaccinations the difference in response to vaccination between the young and elderly age groups declined rapidly. Although age is an important factor when modeling the outcome of the first vaccination, this term lost its relevance with successive vaccinations. In fact, when we examined the data with the assumption that the elderly group had received (on average) as few as two vaccinations prior to our study, the difference due to age disappeared. Our analyses therefore show that the initial difference between the two age groups in their response to vaccination may not be uniquely explained by immunosenescence due to ageing of the immune system, but could equally be the result of the different pre-study vaccination and infection histories in the elderly.Supported by the NIH First Award R29AG11876 (PI: D. Powers), NIH Director's Pioneer Award, program grant P0050/2008 from the Human Frontier Science Program, European Union FP7 program EMPERIE (22349). This work was supported by the award of a Fellowship in Biomedical Informatics from the Medical Research Council (UK) and a Junior Research Fellowship from Homerton College Cambridge to JMF.This is the final version of the article. It was first available from Elsevier via http://dx.doi.org/10.1016/j.vaccine.2015.11.05