Tightly Coupled GNSS and Vision Navigation for Unmanned Air Vehicle Applications

This paper explores the unique benefits that can be obtained from a tight integration of a GNSS sensor and a forward-looking vision sensor. The motivation of this research is the belief that both GNSS and vision will be integral features of future UAV avionics architectures, GNSS for basic aircraft navigation and vision for obstacle-aircraft collision avoidance. The paper will show that utilising basic single-antenna GNSS measurements and observables, along with aircraft information derived from optical flow techniques creates unique synergies. Results of the accuracy of attitude estimates will be presented, based a comprehensive Matlab® Simulink® model which re-creates an optical flow stream based on the flight of an aircraft. This paper establishes the viability of this novel integrated GNSS/Vision approach for use as the complete UAV sensor package, or as a backup sensor for an inertial navigation system

Mathematical analysis of a discrete fracture model coupling Darcy flow in the matrix with Darcy-Forchheimer flow in the fracture

We consider a model for flow in a porous medium with a fracture in which the flow in the fracture is governed by the Darcy-Forchheimer law while that in the surrounding matrix is governed by Darcy's law. We give an appropriate mixed, variational formulation and show existence and uniqueness of the solution. To show existence we give an analogous formulation for the model in which the Darcy-Forchheimer law is the governing equation throughout the domain. We show existence and uniqueness of the solution and show that the solution for the model with Darcy's law in the matrix is the weak limit of solutions of the model with the Darcy-Forchheimer law in the entire domain when the Forchheimer coefficient in the matrix tends toward zero

Optimal scaling for partially updating MCMC algorithms

In this paper we shall consider optimal scaling problems for high-dimensional Metropolis--Hastings algorithms where updates can be chosen to be lower dimensional than the target density itself. We find that the optimal scaling rule for the Metropolis algorithm, which tunes the overall algorithm acceptance rate to be 0.234, holds for the so-called Metropolis-within-Gibbs algorithm as well. Furthermore, the optimal efficiency obtainable is independent of the dimensionality of the update rule. This has important implications for the MCMC practitioner since high-dimensional updates are generally computationally more demanding, so that lower-dimensional updates are therefore to be preferred. Similar results with rather different conclusions are given for so-called Langevin updates. In this case, it is found that high-dimensional updates are frequently most efficient, even taking into account computing costs.Comment: Published at http://dx.doi.org/10.1214/105051605000000791 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

Understanding effective management of postoperative wounds

Acute surgical wounds generally heal with no problems. However, some wounds blister around the periwound area and surgical site infection postoperatively, partly due to inappropriate choice of wound dressing. These complications can cause pain, discomfort, persistent wound leakage, and possible risk of surgical site infection (Jester et al, 2000; Bhattacharyya et al, 2005; Cosker et al, 2005). Postoperative blistering and infection have been identified as the main problems in hip and knee replacement surgery (Ravenscroft et al, 2006)

A New Method for Exposing Deposit Feeders to Contaminated Sediments for Food Chain Studies

(excerpt) The ubiquity and refractory nature of certain organic compounds, such as chlorinated pesticides and polychlorinated biphenyls (PCB\u27s), results in their accumulation in aquatic sediments (Holdrinet et al. 1978, Peck et al. 1980, Wang et al. 1979). Their continuous release from this reservoir through physico-chemical and biogenic processes to the overlying water column results in the accumulation of xenobiotic compounds in the food chain

The myth of the overworked American

A challenge to the popular presumption that U.S. workers are experiencing declining levels of leisure time, finding that the total hours of work have not changed much over the past decade, but that the composition of labor has shifted from home work to market work, mostly as a result of changes in the total hours worked by women.Labor productivity

Economic precariousness and living in the parental home in the UK

Today’s young adults are facing increased economic uncertainty as a result of unemployment, the continued growth of low-paid, insecure and often part-time employment, accelerated by the recent economic downturn. Recent media attention has focused on the trend for increased co-residence of adult children with their parent(s). It is generally assumed that this trend relates directly to the increased economic uncertainty of young adults, combined with the challenges of affordability in the housing market. This research is motivated by the need to identify which groups are most at risk of economic uncertainty and to investigate the consequences for young adults’ abilities to make successful transitions to adulthood. The paper contributes to the literature on both youth employment and housing transitions and the intersection of both. The aim of the paper is three fold: 1) To explore how different aspects of precariousness (labour market insecurity, employment insecurity, and income insecurity) can be operationalised using quantitative data; 2) To use these indicators to provide estimates of precarity amongst young men and women aged 18-34; 3) To examine how these indicators are related to the likelihood of living in the parental home. We use data from the first wave of the United Kingdom Household Longitudinal Study (UKHLS) which was conducted in 2009/10, at the height of the economic downturn. By disaggregating analyses by gender and age we get beneath aggregate summary statistics and provide new insights into how young people’s experience of employment changes across the transition from older teenager, to those in their twenties and for those in their early thirties. The survey data suggest considerable income inequalities between young adults. Not surprisingly, the unemployed and economically inactive are concentrated in the lowest income quartiles. Among employed young adults, income levels differ significantly according to the hours worked, and occupational status. Our analyses show that young people are over-represented in routine and semi-routine jobs, most of these jobs tend to be low-paid and are in the bottom income quartile. Whilst the proportion in routine and semi-routine jobs decreases with age as young people gain the necessary skills and experience to climb the occupational ladder, a sizeable proportion – about one in five men and women in their early thirties remain in a routine or semi-routine job.A significant minority of young adults are self-employed. Among this group, we find a bi-modal income distribution, suggesting that for some, self-employment is an entrepreneurial success story. However, over one half of the self-employed in their late twenties and early thirties are in the lowest quartile suggesting that for others, self-employment is a new form of precarity. This research also quantifies the extent to which different indicators of precarity are related. We find that young adults often face multiple dimensions of economic precarity. For example, male part-time workers tend to have lower personal incomes, and part-time work is associated with being on a temporary contract and being in semi-routine or routine jobs. Almost all the indicators of precariousness were found to be associated with a higher likelihood of living in the parental home, suggesting that these young adults face constraints on their ability to make the transition to residential independence. Some differences are seen according to age. For men and women aged under 25, both unemployment, being temporary or part-time employed, or being in a (semi)routine job are associated with a higher likelihood of remaining in the parental home. By their late twenties only a small proportion of women, but a higher proportion of men remain living with their parents. At these ages, it is unemployed and economically inactive and men in (semi) routine jobs, and men with lower levels of personal income who are significantly more likely to remain living with their parent(s). This research has implications for various actors including national and local government, housing agencies and employee groups as well as the self-employed. Young adults are concentrated in parts of the economy dominated by zero and short-hours contracts and governments should regulate these types of contracts. In addition, uncertainties associated with self-employment need to be recognised since they may have implications for making stable housing and family transitions. New policies need to consider the groups struggling most with housing costs; young single people, especially those without children, who are renting single bedroom properties, particularly in London. Furthermore, policies need to be developed to support pay and skills progression among young adults.<br/

Measuring economic precarity among UK youth during the recession

What are the key aspects of economic precariousness and which are most relevant to analysing young people’s lives? In this study we use data from the United Kingdom Household Longitudinal Study (UKHLS) to identify the proportion of men and women aged 18-34 who might be considered to be in an economically precarious situation and investigate how the dimensions of precariousness are interrelated. This paper summarises findings from the CPC Working Paper 55

Educational aspirations among UK young teenagers: exploring the role of gender, class and ethnicity

This paper presents an overview of teenagers’ aspirations for higher levels of education during the recent economic recession. We analyse the responses of 4899 young people aged 10 to 15, who participated in the UK Household Longitudinal Study in 2009-10. The timing of the survey is especially significant given the political emphasis on raising aspirations as a means to stimulate the economy. We consider the impact of gender, parental occupational class, parental educational background, family structure and parental attitudes towards education upon teenagers’ educational aspirations, and use multiple regression analyses to consider whether their effects are consistent across ethnic groups. Until now, only limited nationally representative data on young people’s aspirations have been available, especially in respect of ethnic differences. This research aims to fill that gap. It was undertaken as part of a wider study into the aspirations for living and learning among young people in the UK