Comparative study of two dynamics-model-based estimation algorithms for distributed drive electric vehicles

The effect of vehicle active safety systems is subject to the accurate knowledge of vehicle states. Therefore, it is of great importance to develop a precise and robust estimation approach so as to deal with nonlinear vehicle dynamics systems. In this paper, a planar vehicle model with a simplified tire model is established first. Two advanced model-based estimation algorithms, an unscented Kalman filter and a moving horizon estimation, are developed for distributed drive electric vehicles. Using the proposed algorithms, vehicle longitudinal velocity, lateral velocity, yaw rate as well as lateral tire forces are estimated based on information fusion of standard sensors in today’s typical vehicle and feedback signals from electric motors. Computer simulations are implemented in the environment of CarSim combined with Matlab/Simulink. The performance of both estimators regarding convergence, accuracy, and robustness against an incorrect initial estimate of longitudinal velocity is compared in detail. The comparison results demonstrate that both estimation approaches have favourable coincidence with the corresponding reference values, while the moving horizon estimation is more accurate and robust, and owns faster convergence.DFG, 325093850, Open Access Publizieren 2017 - 2018 / Technische Universität Berli

Distribution of Soil Organic Carbon Fractions as Related to Land Use and Management in the Loess Plateau, Northern China

Organic C in the soil is not a uniform material but rather a complex mixture of plant, animal and microbial residues at different stages of decomposition (Post and Kwon 2000). So the dynamics of soil organic carbon (SOC) is usually described by dividing total SOC into different fractions (Six et al. 2002). Of all the different fractions, density defined fractions (light- and heavy fractions) may relate better to specific functions or processes (O’Hara et al. 2006), and the changes in SOC due to land use and management may be partly explained by the way C is allocated in these different SOC fractions (Tan et al. 2007). Previous research in the Loess Plateau of northern China indicate that, compared with the grassland restored from cropping, continuous tillage and proper management in cropland increased SOC storage in the lower soil horizons (Li et al. 2008). This study was conducted to investigate the distribution of light- and heavy fractions of SOC under cropland and grassland, aiming to better understand how the density fractions of SOC were affected by the land use conversion

Effects of Rain Events on Carbon Fluxes from Biological Soil Crusts

In dry ecosystems, biological soil crusts (BSCs) have been suggested as one of the factors responsible for the large rate of annual CO2 net uptake (Xie et al. 2009). However, most studies carried out on carbon (C) fluxes in arid and semi-arid ecosystems, such as soil respiration, have neglected the carbon fluxes from BSCs. Although BSCs are a vital component of the dry-land soil C cycle, few studies have parameterized the conditions required for photosynthesis in BSCs or determined BSCs respiration (Elbert et al. 2009, Castillo-Monroy et al. 2011). Precipitation in dry land is dominated by small events (Lauenroth and Bradford 2009). Even the smallest events will influence the carbon fluxes of BSCs, while intermediate pulses might wet the subsurface biotic community, and typically only larger events are used by plants for carbon gain or growth of roots or shoots (Belnap et al. 2005). As BSCs dry quickly and are hence very responsive to moisture pulses, the pulsed nature of precipitation can lead to highly variable carbon fluxes from BSCs (Bowling et al. 2011). Therefore, it is very important to study the effect of rain events upon carbon fluxes through BSCs in the dry ecosystem