Untersuchungen zur ergonomiegerechten Gestaltung der Mensch-Maschine- Schnittstellen von aktuellen Pkw-Bremsanlagen

Die Rückgewinnung von kinetischer Fahrzeugenergie beim Bremsvorgang ist eine wichtige Maßnahme zur Effizienzerhöhung von Kraftfahrzeugen mit Elektromotor. Je nach maximal verfügbarem rekuperativen Bremsmoment und Bremssituation muss ein zusätzlicher Anteil an Reibbremsmoment erzeugt werden, um das Zielbremsmoment zu erreichen. Solche Pkw-Bremsanlagen stellen besondere Anforderungen an die ergonomiegerechte Ausgestaltung der Mensch-Maschine-Schnittstellen. Zunächst werden Möglichkeiten zur Erfassung der Abläufe bei der Bremsbetätigung aus humanphysiologischer Sicht beschrieben. Die Besonderheiten unterschiedlicher entkoppelter Bremsanlagen werden unter Nutzung einer speziell für solche Anwendungen entwickelten Pedalbetätigungsautomatik herausgearbeitet. Einen weiteren Schwerpunkt bilden gezielte Probandenuntersuchungen zu Fühlbarkeits- und Akzeptanzschwellen des Fahrers bei der Bremsbetätigung. Abschließend werden Empfehlungen für die Auslegung von Bremsanlagen mit Schwerpunkt auf den Pedalcharakteristiksimulatoren und Bremsmomenterzeugungssystemen von entkoppelten Bremsanlagen abgeleitet.The recovery of the kinetic energy of the car during braking is an important measure to increase the efficiency of electric and hybrid electric vehicles. Till today, no car in series production is known that brakes exclusively via recuperative brake torque and therefore disclaims of a conventional friction brake at all. Depending on the maximum available recuperative brake torque and the braking situation an additional frictional braking moment has to be generated to reach the total brake torque demand. Such braking systems have special requirements for the design of the human-machine interface. This thesis is a contribution to ergonomics-oriented design of human-machine-interfaces of current passenger car braking systems. In particular this includes recuperative braking systems and decoupled braking systems. Basic methodologies are developed and applied, considering physiological and psychological factors beside the technical aspects. First, methods to capture the processes during the brake actuation are described from the human physiological point of view. It examines the influences of cockpit designs, braking maneuvers, driver and brake pedal characteristics on the actuation processes. The special characteristics of different decoupled braking systems are evaluated using a purpose-built pedal actuation robot. In particular, potentially perturbations which may occur during regenerative braking (e. g. disturbances in the deceleration behavior) and the pedal characteristic simulation (unsuitable and/or synthetic pedal and braking characteristics) are in the focus of attention. Another focus deals with customer clinics regarding tactility and acceptance thresholds of the driver during the brake actuation. Basic examinations will be presented that indicate, which characteristics of the brake feel of decoupled brake systems can be recognized or even be disturbing for the driver. Finally, recommendations for the design of pedal characteristic simulators and decoupled brake systems will be given

Research in hydraulic brake components and operational factors influencing the hysteresis losses

Up-to-date automotive brake systems place stringent requirements upon the performance, reliability, and active safety. Such advanced systems as antilock braking systems (ABS), the electronic stability programme system, and the anti-slip control system assist a driver in ensuring driving safety under many conditions. The influence of the brake components on active safety systems is mainly determined through the hysteresis loop width. Among other negative outcomes, this parameter limits the possible frequency of cyclic braking during ABS operation. This paper presents an experimental analysis of the factors influencing the hysteresis pressure losses in a hydraulic brake system. The factors under investigations are the brake pedal stroke velocity, the gaps between the brake pads and the brake disc, and the configuration of the brake system. Experiments were carried out on the brake test equipment at the Automotive Engineering Department, Faculty for Mechanical Engineering, Technische Universität Ilmenau, Germany

Cathepsin D Expression and Gemcitabine Resistance in Pancreatic Cancer.

BackgroundCathepsin-D (CatD), owing to its dual role as a proteolytic enzyme and as a ligand, has been implicated in cancer progression. The role of CatD in pancreatic ductal adenocarcinoma is unknown.MethodsCatD expression quantified by immunohistochemistry of tumor-tissue microarrays of 403 resected pancreatic cancer patients from the ESPAC-Tplus trial, a translational study within the ESPAC (European Study Group for Pancreatic Cancer) trials, was dichotomously distributed to low and high H scores (cut off 22.35) for survival and multivariable analysis. The validation cohort (n = 69) was recruited based on the hazard ratio of CatD from ESPAC-Tplus. 5-fluorouracil-, and gemcitabine-resistant pancreatic cancer cell lines were employed for mechanistic experiments. All statistical tests were two-sided.ResultsMedian overall survival was 23.75 months and median overall survival for patients with high CatD expression was 21.09 (95% confidence interval [CI] = 17.31 to 24.80) months vs 27.20 (95% CI = 23.75 to 31.90) months for low CatD expression (χ2 LR, 1DF = 4.00; P = .04). Multivariable analysis revealed CatD expression as a predictive marker in gemcitabine-treated (z stat = 2.33; P = .02) but not in 5-fluorouracil-treated (z stat = 0.21; P = .82) patients. An independent validation cohort confirmed CatD as a negative predictive marker for survival (χ2 LR, 1DF = 6.80; P = .009) and as an independent predictive marker in gemcitabine-treated patients with a hazard ratio of 3.38 (95% CI = 1.36 to 8.38, P = .008). Overexpression of CatD was associated with a concomitant suppression of the acid sphingomyelinase, and silencing of CatD resulted in upregulation of acid sphingomyelinase with rescue of gemcitabine resistance.ConclusionsAdjuvant gemcitabine is less effective in pancreatic ductal adenocarcinoma with high CatD expression, and thus CatD could serve as a marker for biomarker-driven therapy