The trade-off between taxi time and fuel consumption in airport ground movement

Environmental impact is a very important agenda item in many sectors nowadays, which the air transportation sector is also trying to reduce as much as possible. One area which has remained relatively unexplored in this context is the ground movement problem for aircraft on the airport’s surface. Aircraft have to be routed from a gate to a runway and vice versa and it is still unknown whether fuel burn and environmental impact reductions will best result from purely minimising the taxi times or whether it is also important to avoid multiple acceleration phases. This paper presents a newly developed multi-objective approach for analysing the trade-off between taxi time and fuel consumption during taxiing. The approach consists of a combination of a graph-based routing algorithm and a population adaptive immune algorithm to discover different speed profiles of aircraft. Analysis with data from a European hub airport has highlighted the impressive performance of the new approach. Furthermore, it is shown that the trade-off between taxi time and fuel consumption is very sensitive to the fuel-related objective function which is used

Short Communication: Development of a food composition table to analyze Senegalese food expenditure data

Household Consumption and Expenditure Surveys (HCES) are increasingly used to estimate the potential of food fortification programs. Senegal’s latest HCES, Enquête de Suivi de la Pauvreté au Sénégal, was completed in 2011. As no Senegalese food composition table exists, one had to be constructed to analyze Senegal’s HCES, which contains 50 foods or food groups. These are millet, sorghum, maize, fonio, millet porridge, whole rice, broken rice, red rice, groundnut, peanut paste, groundnut paste, palm oil, vegetable oil, groundnut oil, soya oil, tomato paste, cabbage, tomato, onion, dried cowpea, bouillon cube, mango, fried egg sandwich, salt, herring, smoked catfish, dried whitefish, beef, goat, lamb, pork, chicken, sugar, coffee bean, instant coffee, green tea, hibiscus tea, Coca Cola, baobab fruit, beer, baguette, croissant, water biscuit, yoghurt, powder milk, milk, and gruyere cheese. A food composition table was constructed with 13 micronutrients (biotin, folate, iodine, iron, niacin, pantothenic acid, riboflavin, thiamin, vitamin A, vitamin B6, vitamin B12, vitamin D, and zinc) for the 50 food items in the Household Consumption and Expenditure Survey. Nutrient information was collected from the Table de Composition des Aliments d'Afrique de l'Ouest, United States Department of Agriculture’s Food Composition Databases, Frida Fooddata, several journals, and books. In the survey, there were food groups such as alcoholic beverages that needed to be reclassified as a specific food, such as beer, to construct the food composition table. To accomplish this, food balance sheet data from the Food and Agriculture Organization of the United Nations were used as well as information from a Senegalese key informant. To consider the potential impact of food fortification on apparent nutrient intakes, nutrient information for ten fortified foods (bouillon cube, salt, palm oil, vegetable oil, groundnut oil, soya oil, and four wheat flour-containing foods such as baguette, croissant, water biscuit, and fried egg sandwich) were also included in the food composition table. With the newly developed Senegalese food composition table, it is possible to analyze Senegal’s 2011 HCES.Keywords: Micronutrients, Nutrient Database, West Africa, Household Income and Expenditure Survey, Senega

Halving Balls in Deterministic Linear Time

Let \D be a set of $n$ pairwise disjoint unit balls in $\R^d$ and $P$ the set of their center points. A hyperplane \Hy is an \emph{$m$-separator} for \D if each closed halfspace bounded by \Hy contains at least $m$ points from $P$. This generalizes the notion of halving hyperplanes, which correspond to $n/2$-separators. The analogous notion for point sets has been well studied. Separators have various applications, for instance, in divide-and-conquer schemes. In such a scheme any ball that is intersected by the separating hyperplane may still interact with both sides of the partition. Therefore it is desirable that the separating hyperplane intersects a small number of balls only. We present three deterministic algorithms to bisect or approximately bisect a given set of disjoint unit balls by a hyperplane: Firstly, we present a simple linear-time algorithm to construct an $\alpha n$-separator for balls in $\R^d$, for any $0<\alpha<1/2$, that intersects at most $cn^{(d-1)/d}$ balls, for some constant $c$ that depends on $d$ and $\alpha$. The number of intersected balls is best possible up to the constant $c$. Secondly, we present a near-linear time algorithm to construct an $(n/2-o(n))$-separator in $\R^d$ that intersects $o(n)$ balls. Finally, we give a linear-time algorithm to construct a halving line in $\R^2$ that intersects $O(n^{(5/6)+\epsilon})$ disks. Our results improve the runtime of a disk sliding algorithm by Bereg, Dumitrescu and Pach. In addition, our results improve and derandomize an algorithm to construct a space decomposition used by L{\"o}ffler and Mulzer to construct an onion (convex layer) decomposition for imprecise points (any point resides at an unknown location within a given disk)

Do Race and Ethnicity Matter? An Examination of Racial/Ethnic Differences in Perceptions of Procedural Justice and Recidivism Among Problem-Solving Court Clients

Over the years, a distinct body of research has emerged that examines procedural justice in problem-solving courts. However, there is virtually no research to date on racial and ethnic differences in perceptions of procedural justice among problem-solving court clients. The present study seeks to understand the complexities of judicial procedural justice and race/ethnicity within problem-solving courts. Using a convenience sample of 132 clients from two problem-solving courts in a southern state, this study addresses a void in the literature by examining the influence of race/ethnicity on perceptions of procedural justice as well as the impact of race/ethnicity and procedural justice on clients’ likelihood of recidivism. Results suggest that Black problem-solving court clients’ have significantly lower perceptions of procedural justice, while also having a lower likelihood of recidivism. Perceptions of procedural justice did not influence recidivism outcomes. Policy implications and recommendations for future research are discussed

On the temporal analysis of acoustic waves using schlieren imaging

The primary objective of the present study was to develop a quantitative schlieren-imaging technique that can be used to study the dynamics of instability waves. The technique was initially validated by optically capturing a controlled acoustic wave generated by a compression driver and excellent agreement was obtained with microphone measurements. An underexpanded jet was considered as an ideal test case due to the complexity and multitude of instability mechanism. Further analysis of the underexpanded jet demonstrated that this technique can be used to capture the very high frequency mode related to the phenomenon of screech

Lessons from building an automated pre-departure sequencer for airports

Commercial airports are under increasing pressure to comply with the Eurocontrol collaborative decision making (CDM) initiative, to ensure that information is passed between stakeholders, integrate automated decision support or make predictions. These systems can also aid effective operations beyond the airport by communicating scheduling decisions to other relevant parties, such as Eurocontrol, for passing on to downstream airports and enabling overall airspace improvements. One of the major CDM components is aimed at producing the target take-off times and target startup-approval times, i.e. scheduling when the aircraft should push back from the gates and start their engines and when they will take off. For medium-sized airports, a common choice for this is a “pre-departure sequencer” (PDS). In this paper, we describe the design and requirements challenges which arose during our development of a PDS system for medium sized international airports. Firstly, the scheduling problem is highly dynamic and event driven. Secondly, it is important to end-users that the system be predictable and, as far as possible, transparent in its operation, with decisions that can be explained. Thirdly, users can override decisions, and this information has to be taken into account. Finally, it is important that the system is as fair as possible for all users of the airport, and the interpretation of this is considered here. Together, these factors have influenced the design of the PDS system which has been built to work within an existing large system which is being used at many airport

The effect of treatment of liraglutide on quality of life and depression in young obese women with PCOS and controls

Polycystic ovary syndrome (PCOS) is associated with reduced quality of life (QoL), though the role of associated obesity is unclear. In this study we examined the effects of six months treatment with liraglutide, 1.8 mg od, on obesity, depression and QoL in young women with PCOS and obesity compared to age- and weight-matched controls. In a cross-sectional study, 36 women were recruited (19 PCOS, 17 controls), age 33.9 ± 6.7 vs. 33.5 ± 7.1 yr, and weight 102.1 ± 17.1 vs. 100.4 ± 15.1 kg, respectively. PCOS was diagnosed according to the Rotterdam criteria. Depression was measured using the Centre for Epidemiologic Studies Depression Scale (CES-D). QoL was measured using the World Health Organization QoL questionnaire (WHOQOL-BREF). At baseline there was no difference in QoL or CES-D scores between the two groups. At six months, weight was reduced by 3.0 ± 4.2 kg, p = .01, in the PCOS group and 3.8 ± 3.4 kg, p = .001, in controls. Psychological health improved in the PCOS group (percentage change 11.3%, p smaller than .02). Combining the two groups revealed significant improvement (p smaller than .05) in physical (82.6 ± 11.2 vs. 78.9 ± 13.6), psychological (62.4 ± 16.5 vs. 57.5 ± 16.4) and social health (76.6 ± 15.3 vs. 71 ± 16.8) components of the WHOQOL-BREF at six months. Weight loss is associated with an improvement in QoL; and when matched for age and obesity, PCOS was not independently associated with reduced QoL or depression