T. Esch

Efficient musical noise suppression for speech enhancement system

Noise reduction techniques that are relying on spectral weighting rules often generate annoying musical noise artifacts in the processed signal. In this paper, we present a postfilter (PF) for the spectral weighting gains that is capable of reducing musical noise in a simple but efficient way. It includes a robust detector for speech pauses and low SNR conditions and adaptively smoothes the weighting gains over frequency based on soft-decisions. Objective and subjective measurements show consistent improvements if the postfilter is applied to conventional noise reduction techniques.

Der elektromechanische Ventiltrieb — Systembaustein für zukünftige Antriebskonzepte Teil 1

Aktuell werden unterschiedliche Konzepte verfolgt, welche ausgehend vom konventionellen Ottomotor mit Saugrohreinspritzung darauf abzielen, die prinzipbedingten Nachteile des ottomotorischen Arbeitsverfahrens gegenuber dem Dieselmotor zu uberwinden. Die vorhandenen Nachteile beruhen im wesentlichen auf der Drosselsteuerung des Ottomotors. Eine teilweise Entdrosselung des Motors ist bereits mit einfachen Nockenwellen-Phasenstellern moglich. Durch die Betriebspunktverlagerung beim Down-Sizing wird ebenfalls eine Teilentdrosselung erzielt. Ein konsequenterer Weg zur Reduzierung der Drosselverluste stellt der Schichtbetrieb beim DI-Ottomotor dar. Mittels einer variablen Steuerung der Gaswechselventile ist dagegen die vollstandige Vermeidung der Drosselverluste erreichbar. Der folgende Artikel beschreibt das elektromechanische Ventilsteuersystem EMVT der FEV Motorentechnik mit variabler Ein- und Auslasssteuerung der Ventile, dessen Integration ins Fahrzeug, sowie zukunftig wichtige Entwicklungsrichtungen und -schwerpunkte. Teil 2 des Beitrags wird den Motorprozess und die Antriebskonzepte behandeln und in MTZ 1/2001 erscheinen.

Thermal Management in E-Carsharing Vehicles—Preconditioning Concepts of Passenger Compartments

The issue of thermal management in electric vehicles includes the topics of drivetrain cooling and heating, interior temperature, vehicle body conditioning and safety. In addition to the need to ensure optimal thermal operating conditions of the drivetrain components (drive motor, battery and electrical components), thermal comfort must be provided for the passengers. Thermal comfort is defined as the feeling which expresses the satisfaction of the passengers with the ambient conditions in the compartment. The influencing factors on thermal comfort are the temperature and humidity as well as the speed of the indoor air and the clothing and the activity of the passengers, in addition to the thermal radiation and the temperatures of the interior surfaces. The generation and the maintenance of free visibility (ice- and moisture-free windows) count just as important as on-demand heating and cooling of the entire vehicle. A Carsharing climate concept of the innovative ec2go vehicle stipulates and allows for only seating areas used by passengers to be thermally conditioned in a close-to-body manner. To enable this, a particular feature has been added to the preconditioning of the Carsharing electric vehicle during the electric charging phase at the parking station.

Trends in commercial vehicle powertrains

Low emission zones and truck bans, the rising price of diesel and increases in road tolls: all of these factors are putting serious pressure on the transport industry. Commercial vehicle manufacturers and their suppliers are in the process of identifying new solutions to these challenges as part of their efforts to meet the EEV (enhanced environmentally friendly vehicle) limits, which are currently the most robust European exhaust and emissions standards for trucks and buses.

Trends in der Nutzfahrzeug-Antriebstechnik

Umweltzonen und Fahrverbote, kletternde Dieselpreise und steigende Strasenbenutzungsgebuhren setzen dem Transportgewerbe aktuell schwer zu. Nutzfahrzeughersteller und Partner finden auf diese Herausforderungen neue Antworten mit der Erfullung der EEV-Grenzwerte (Enhanced Environmentally Friendly Vehicle) als den gegenwartig anspruchsvollsten europaischen Abgasstandard fur Lkw und Busse.

Investigation of Flow Separation Inside a Conical Rocket Nozzle With the Aid of an Annular Cross Flow

Flow separation is a phenomenon that occurs in all kinds of supersonic nozzles sometimes during run-up and shut-down operations. Especially in expansion nozzles of rocket engines with large area ratio, flow separation can trigger strong side loads that can damage the structure of the nozzle. The investigation presented in this paper seeks to establish measures that may be applied to alter the point of flow separation. In order to achieve this, a supersonic nozzle was placed at the exit plane of the conical nozzle.

Innovative modular valve trains for 2015 logistic benefits by EMVT

Abstract In this paper the way to a 5-day-car with respect to a modular valve train systems for spark ignited combustion engines is shown. The necessary product diversity is shift from mechanical or physical components to software components. Therefore, significant improvements of logistic indicators are expected and shown. The working principle of a camless cylinder head with respect to an electromagnetical valve train (EMVT) is explained and it is demonstrated that shifting physical diversity to software is feasible. The future design of combustion engine systems including customisation can be supported by a set of assistance tools which is shown exemplary.