Lateral string stability of vehicle platoons

This internship report is part of a larger assignment which is an analysis of lateral string stability and the development of a controller design method with guaranteed lateral string stability. Lateral string stability is an issue when a look-ahead sensing method is used in combination with a vehicle-following control strategy. The coupling between vehicles enables errors to increase while they propagate upstream through a string of vehicles. Communicating desired yaw rate or lateral acceleration and use this information for controller design could be an option to achieved guaranteed lateral string stability. One of the applications of lateral control will be conducting maneuvers like merging or lane changes. During these maneuvers the side-slip angles of the tyres stay within theinterval of linear tyre response, this means that side-slip angles of the tyres are within 0:5. On this interval the non-linear and linearized tyre model have the same linear response. This makes is possible to use a linearized vehicle model with linear tyres for the modeling of the lateral and yaw dynamics of the vehicle. This is validated using experimental data and it is shown that the response of the linearized vehicle model is almost equal to the actual vehicle response

"Connect & drive" C&D C-ACC for reducing congestion dynamics

This paper concentrates on a recently started project (Q4-2008), entitled "Connect &amp; Drive" (C&amp;D) defined in The Netherlands and subsidized by government funding. This project combines Adaptive Cruise Control techniques, vehicle-to-vehicle and vehicle-to-infrastructure communication to dampen congestion dynamics. This is termed "Cooperative Adaptive Cruise Control" (CACC). The use of this Advanced Driver Assistant (ADA) system will result in currently unforeseeable benefits on emissions and congestions, particularly since they are mutually enforcing mechanisms. The paper describes the Connect &amp; Drive definition, motivation for this definition and some preliminary expected results on congestion damping. Furthermore, the underlying research and development work that is currently ongoing in The Netherlands within the framework of the Connect &amp; Drive project is also briefly addressed throughout the paper.</p

Educational differences in the validity of self-reported physical activity

BACKGROUND: The assessment of physical activity for surveillance or population based studies is usually done with self-report questionnaires. However, bias in self-reported physical activity may be greater in lower educated than in higher educated populations. The aim of the present study is to describe educational differences in the validity of self-reported physical activity. METHODS: We included 196 healthy adults (age 57 ± 15.4, of whom 17 % low, 24 % medium and 59 % high educated). Criterion validity of an adapted International Physical Activity Questionnaire was assessed against the ActiGraph GT3X+ accelerometer. RESULTS: While criterion validity of self-reported physical activity was low to moderate in the total sample (Spearman rho ranged from 0.16 to 0.27, depending on the variables used), the validity in lower educated respondents was poor (-0.07 to 0.05). CONCLUSIONS: The results confirm the hypothesis that self-report physical activity questionnaires are less valid in lower educated populations

European Sitting Championship: Prevalence and Correlates of Self-Reported Sitting Time in the 28 European Union Member States

Objective: Sedentary behaviour is increasingly recognized as an important health risk, but comparable data across Europe are scarce. The objective of this study was to explore the prevalence and correlates of self-reported sitting time in adults across and within the 28 European Union Member States. Methods: This study reports data from the Special Eurobarometer 412. In 2013, 27,919 randomly selected Europeans (approximately 1000 per Member State) were interviewed face-to-face. Sitting time on a usual day was self-reported and dichotomised into sitting less- and more than 7.5 hours per day. Uni- and multivariate odds ratios of sitting more than 7.5 hours per day were assessed by country and socio-demographic variables using binary logistic regression analyses. The analyses were stratified by country to study the socio-demographic correlates of sitting time within the different countries. Results: A total of 26,617 respondents were included in the analyses. Median sitting time was five hours per day. Across Europe, 18.5 percent of the respondents reported to sit more than 7.5 hours per day, with substantial variation between countries (ranging from 8.9 to 32.1 percent). In general, northern European countries reported more sitting than countries in the south of Europe. ‘Current occupation’ and ‘age when stopped education’ were found to be the strongest correlates of sitting time, both across Europe and within most Member States. Compared to manual workers, the odds ratio of sitting more than 7.5 hours per day was 5.00 for people with white collar occupations, 3.84 for students, and 3.65 for managers. Conclusions: There is substantial variation in self-reported sitting time among European adults across countries as well as socio-demographic groups. While regular surveillance of (objectively measured) sedentary behaviour is needed, the results of this study provide entry points for developing targeted interventions aimed at highly sedentary populations, such as people with sedentary occupations

Interpretation of results from on-farm experiments: manure-nitrogen recovery on grassland as affected by manure quality and application technique. 1. An agronomic analysis

In a 5-year field experiment, a comparison was made between the manure application practices of two adjacent dairy farms in the north of the Netherlands. Grassland management systems at Drogeham and Harkema contrasted in manure application technique (surface application versus shallow injection, respectively), quality of applied manure (slurry + MX: slurry with Euromestmix&reg; clay mineral additive versus regular slurry), and some relevant site characteristics (high versus low soil organic matter content and soil moisture supply). Effects of manure types and application techniques, and treatment of the soil with a micro-organism supplement, were tested in a factorial experiment at the two sites, two blocks per site, one with and one without additional application of 157 kg N ha–1 year–1 inorganic fertilizer. Apparent N recovery was higher after shallow injection than after surface application. For plots receiving no additional inorganic fertilizer, this difference was largest for slurry + MX applied at site Harkema, since this slurry–site combination resulted in the highest observed average apparent N recovery following shallow injection (47%) and the lowest N recovery following surface application (20%). For plots receiving additional inorganic fertilizer N the contrasts between treatments were less pronounced. Year effects on N uptake and dry matter production could be related to cumulative temperature and precipitation surplus over the growing season. A simple comparison between the grassland management systems was carried out based on the response curves derived from the experiment. This demonstrated that the grassland system where slurry was applied by shallow injection is not necessarily the lowest in actual amount of N not accounted for (i.e., potentially lost). The efficiency of the Harkema system strongly depended on high N recovery, but showed high potential losses in some years and a high herbage crude protein content in other years, due to the low DM production capacity. On the other hand, the Drogeham system was tuned to high DM production and was characterized by higher system stability, as reflected by more stable relationships between DM production and N not accounted for and herbage crude protein content. These differences between the systems were probably to a large extent caused by differences in water balance and soil organic matter content

Interpretation of results from on-farm experiments: manure-nitrogen recovery on grassland as affected by manure quality and application technique. 2. A sociological analysis

This article discusses the outcomes of a re-analysis of a grassland experiment, by locating it within the wider institutional context composed of well-established routines used in agronomic research and the dominant epistemological tradition of agricultural sciences. It is argued that both, research routines and epistemological tradition, are strategic pillars of the reigning socio-technical regime. They contribute to path-dependency, thus reinforcing the uni-lateral development tendency centring on technological solutions that fit within the dominating regime. An important, albeit probably unintended consequence is that promising novelties are obscured within and through research, thus blocking a potentially highly effective road towards sustainability