Recursive Bayesian Initialization of Localization Based on Ranging and Dead Reckoning

The initialization of the state estimation in a localization scenario based on ranging and dead reckoning is studied. Specifically, we start with a cooperative localization setup and consider the problem of recursively arriving at a uni-modal state estimate with sufficiently low covariance such that covariance based filters can be used to estimate an agent's state subsequently. A number of simplifications/assumptions are made such that the estimation problem can be seen as that of estimating the initial agent state given a deterministic surrounding and dead reckoning. This problem is solved by means of a particle filter and it is described how continual states and covariance estimates are derived from the solution. Finally, simulations are used to illustrate the characteristics of the method and experimental data are briefly presented

A method for inferring hierarchical dynamics in stochastic processes

Complex systems may often be characterized by their hierarchical dynamics. In this paper do we present a method and an operational algorithm that automatically infer this property in a broad range of systems; discrete stochastic processes. The main idea is to systematically explore the set of projections from the state space of a process to smaller state spaces, and to determine which of the projections that impose Markovian dynamics on the coarser level. These projections, which we call Markov projections, then constitute the hierarchical dynamics of the system. The algorithm operates on time series or other statistics, so a priori knowledge of the intrinsic workings of a system is not required in order to determine its hierarchical dynamics. We illustrate the method by applying it to two simple processes; a finite state automaton and an iterated map.Comment: 16 pages, 12 figure

Understanding the Global in Global Finance and Regulation

A simple and statistically robust method for passive clock synchronization in sensor networks is presented. The method is not limited to passive (one-way communication) synchronization, but this scenario justifies the method. The recursive nature of the method and the targeted passive setup mean that it adds a minimum of requirements on the system in which it is used. Statistical characteristics of the method are quantified and real measurements are used to illustrate the robustness and performance gain relative to a naive Kalman filter based clock synchronization. Finally, C++ code that implements the suggested clock synchronization method, is provided in this article.QC 20140423</p

Childhood Poverty and Labour Market Exclusion. Findings from a Swedish Birth Cohort.

Research has consistently shown that poverty and economic hardship have negative consequences for children. Few studies, however, have examined whether these consequences persists into adulthood. In the present paper we broaden the focus and analyse how living conditions during childhood and adolescence structure socio-economic circumstances also in midlife. How does exposure to poverty during childhood and adolescence affect future probabilities for labour market exclusion and inclusion in early adulthood and in midlife? The data are drawn from a new longitudinal Swedish data set – the Stockholm Birth Cohort Study (SBC) – in which we can follow a cohort of Swedes from birth (1953) to the age of 48 (2001). Our results show that childhood poverty clearly has a negative impact on attainment in adulthood. Persistent poverty in the family of origin and entering poverty in adolescence are particularly detrimental for life chances. This is most salient in the analysis of exclusion in midlife. Educational achievement and deviant behaviour (criminality and drug abuse) are identified as important intervening variables. The results are interpreted as a process of cumulative disadvantage. In our final analyses we focus on those excluded from the labour market in early adulthood and their likelihood to be included in midlife. We find that resource attainment in terms of education and family has positive effects for the chance for inclusion and may in that respect be regarded as turning points.childhood poverty; socio-economic circumstances; labour market exclusion

Alkali-silica reactions in Scania, Sweden : a moisture problem causing pop-outs in concrete floors

Problemen med alkali-kiselsyrareaktioner i Sverige ('AKRIS') är nya och började uppträda då ett cement med högre alkalihalt ersatte det tidigare lågalkalicementet som använts i södra Skåne, där betonggrus normalt innehåller alkalireaktiva korn av opalflinta och opalsandsten.Bara på 'fuktiga inomhuskonsruktioner', som har haft en speciell fukthistoria, har pop-outs uppkommit

A new model for CO₂-absorption of concrete structures. CO₂-cycle in cement and concrete Part 7: Models for CO₂-absorption.

After further laboratory and field studies we have now used the previous and new findings to create a model for CO₂-absorption of concrete structures. Some knowledge is still missing and some results are still not fully understood. In those cases we have done our best to base the model on reasonable assumptions, from what could be expected from some new literature that has been studied

Moisture transport under a temperature gradient – some old and new studies

Moisture transport in concrete under a temperature gradient is a topic that has challenged researchers for at least some 60 years. No conclusions are still drawn on how to describe it theoretically and how to quantify it experimentally. In this paper some of the theoretical and experimental work done is summarized. A description of the flux of moisture by the relative humidity and the water vapour content as the two transport potentials is proposed. A comparison with laboratory and field data is given and the consequences in some applications are discussed

A comparison between different methods to determine moisture transport properties of cementitious materials

A number of methods for measuring moisture transport properties of cementitious materials were compared in a series of experiments. Two OPC mortars with two water-binder-ratios were wet cured for six months and used to produce specimens as discs with different thicknesses and diameters. The cup methods were easy to use, reliable and fairly rapid but need a stable, surrounding, CO2-free climate, however. Evaluating the fundamental potential PSI eliminates the derivation that adds to the uncertainty. Steady-state moisture distribution measurements are very time-consuming and the RH-profiling is a delicate matter. Moisture contents are scattering. Sorption experiments are very easy to perform but difficult to evaluate, because of the peculiar moisture-dependency of the diffusivity Dw and the difficulties to estimate the equilibrium conditions. Initial uniform conditions are difficult to obtain for low w/c-materials, except to initial self-desiccation. Sorption experiments in small steps are uncertain; the initial and final conditions are difficult to define properly