Optimal power harness routing for small-scale satellites

This paper presents an approach to optimal power harness design based on a modified ant colony optimisation algorithm. The optimisation of the harness routing topology is formulated as a constrained multi-objective optimisation problem in which the main objectives are to minimise the length (and therefore the mass) of the harness. The modified ant colony optimisation algorithm automatically routes different types of wiring, creating the optimal harness layout. During the optimisation the length, mass and bundleness of the cables are computed and used as cost functions. The optimisation algorithm works incrementally on a finite set of waypoints, forming a tree, by adding and evaluating one branch at a time, utilising a set of heuristics using the cable length and cable bundling as criteria to select the optimal path. Constraints are introduced as forbidden waypoints through which digital agents (hereafter called ants) cannot travel. The new algorithm developed will be applied to the design of the harness of a small satellite, with results highlighting the capabilities and potentialities of the code

Investigation and modelling of large scale cratering events : Lessons learnt from experimental analysis

Initiated as part of the 2010 Spin Your Thesis campaign, a new ESA Education programme, a group from the University of Glasgow Space Advanced Research Team successfully conducted a series of impact cratering experiments under a highly accelerated reference frame. This aimed to: reproduce and define the physical conditions of large-scale cratering events onto highly porous asteroids; provide cratering response data for the validation and advancement of numerical models; and support the generation of a reliable scaling theory for cratering events. Impact cratering is a fundamental process that has shaped and continues to shape the formation and evolution of our solar system and other planetary systems. Although much is known on the impact dynamics of rocky, brittle bodies, such as asteroids, little is known on the physical response of highly porous bodies. Consequently the physical response of porous bodies can not be compared to conventional models. Therefore throughout the experiment campaign, variation into the target material’s porosity and projectile density was examined. All in-situ measurements were recorded relative to the crater’s morphological profile and ejecta distribution. This occurred under increasing levels of acceleration, thereby validating that the experiment occurred within the crater dominated gravity regime. This paper details the programmatics issues of the initiative, experiences and lessons learnt from the student perspective. From its initial proof-of-concept the Spin Your Thesis campaign provided a solid foundation from the development of an experimental idea, enabling high scientific return and personal development

Optimal dynamic operations scheduling for small-scale satellites

A satellite's operations schedule is crafted based on each subsystem/payload operational needs, while taking into account the available resources on-board. A number of operating modes are carefully designed, each one with a different operations plan that can serve emergency cases, reduced functionality cases, the nominal case, the end of mission case and so on. During the mission span, should any operations planning amendments arise, a new schedule needs to be manually developed and uplinked to the satellite during a communications' window. The current operations planning techniques over a reduced number of solutions while approaching operations scheduling in a rigid manner. Given the complexity of a satellite as a system as well as the numerous restrictions and uncertainties imposed by both environmental and technical parameters, optimising the operations scheduling in an automated fashion can over a flexible approach while enhancing the mission robustness. In this paper we present Opt-OS (Optimised Operations Scheduler), a tool loosely based on the Ant Colony System algorithm, which can solve the Dynamic Operations Scheduling Problem (DOSP). The DOSP is treated as a single-objective multiple constraint discrete optimisation problem, where the objective is to maximise the useful operation time per subsystem on-board while respecting a set of constraints such as the feasible operation timeslot per payload or maintaining the power consumption below a specific threshold. Given basic mission inputs such as the Keplerian elements of the satellite's orbit, its launch date as well as the individual subsystems' power consumption and useful operation periods, Opt-OS outputs the optimal ON/OFF state per subsystem per orbital time step, keeping each subsystem's useful operation time to a maximum while ensuring that constraints such as the power availability threshold are never violated. Opt-OS can provide the flexibility needed for designing an optimal operations schedule on the spot throughout any mission phase as well as the ability to automatically schedule operations in case of emergency. Furthermore, Opt-OS can be used in conjunction with multi-objective optimisation tools for performing full system optimisation. Based on the optimal operations schedule, subsystem design parameters are being optimised in order to achieve the maximal usage of the satellite while keeping its mass minimal

A comparative analysis of algorithms for satellite operations scheduling

Scheduling is employed in everyday life, ranging from meetings to manufacturing and operations among other activities. One instance of scheduling in a complex real-life setting is space mission operations scheduling, i.e. instructing a satellite to perform fitting tasks during predefined time periods with a varied frequency to achieve its mission goals. Mission operations scheduling is pivotal to the success of any space mission, choreographing every task carefully, accounting for technological and environmental limitations and constraints along with mission goals.;It remains standard practice to this day, to generate operations schedules manually ,i.e. to collect requirements from individual stakeholders, collate them into a timeline, compare against feasibility and available satellite resources, and find potential conflicts. Conflict resolution is done by hand, checked by a simulator and uplinked to the satellite weekly. This process is time consuming, bears risks and can be considered sub-optimal.;A pertinent question arises: can we automate the process of satellite mission operations scheduling? And if we can, what method should be used to generate the schedules? In an attempt to address this question, a comparison of algorithms was deemed suitable in order to explore their suitability for this particular application.;The problem of mission operations scheduling was initially studied through literature and numerous interviews with experts. A framework was developed to approximate a generic Low Earth Orbit satellite, its environment and its mission requirements. Optimisation algorithms were chosen from different categories such as single-point stochastic without memory (Simulated Annealing, Random Search), multi-point stochastic with memory (Genetic Algorithm, Ant Colony System, Differential Evolution) and were run both with and without Local Search.;The aforementioned algorithmic set was initially tuned using a single 89-minute Low Earth Orbit of a scientific mission to Mars. It was then applied to scheduling operations during one high altitude Low Earth Orbit (2.4hrs) of an experimental mission.;It was then applied to a realistic test-case inspired by the European Space Agency PROBA-2 mission, comprising a 1 day schedule and subsequently a 7 day schedule - equal to a Short Term Plan as defined by the European Space Agency.;The schedule fitness - corresponding to the Hamming distance between mission requirements and generated schedule - are presented along with the execution time of each run. Algorithmic performance is discussed and put at the disposal of mission operations experts for consideration.Scheduling is employed in everyday life, ranging from meetings to manufacturing and operations among other activities. One instance of scheduling in a complex real-life setting is space mission operations scheduling, i.e. instructing a satellite to perform fitting tasks during predefined time periods with a varied frequency to achieve its mission goals. Mission operations scheduling is pivotal to the success of any space mission, choreographing every task carefully, accounting for technological and environmental limitations and constraints along with mission goals.;It remains standard practice to this day, to generate operations schedules manually ,i.e. to collect requirements from individual stakeholders, collate them into a timeline, compare against feasibility and available satellite resources, and find potential conflicts. Conflict resolution is done by hand, checked by a simulator and uplinked to the satellite weekly. This process is time consuming, bears risks and can be considered sub-optimal.;A pertinent question arises: can we automate the process of satellite mission operations scheduling? And if we can, what method should be used to generate the schedules? In an attempt to address this question, a comparison of algorithms was deemed suitable in order to explore their suitability for this particular application.;The problem of mission operations scheduling was initially studied through literature and numerous interviews with experts. A framework was developed to approximate a generic Low Earth Orbit satellite, its environment and its mission requirements. Optimisation algorithms were chosen from different categories such as single-point stochastic without memory (Simulated Annealing, Random Search), multi-point stochastic with memory (Genetic Algorithm, Ant Colony System, Differential Evolution) and were run both with and without Local Search.;The aforementioned algorithmic set was initially tuned using a single 89-minute Low Earth Orbit of a scientific mission to Mars. It was then applied to scheduling operations during one high altitude Low Earth Orbit (2.4hrs) of an experimental mission.;It was then applied to a realistic test-case inspired by the European Space Agency PROBA-2 mission, comprising a 1 day schedule and subsequently a 7 day schedule - equal to a Short Term Plan as defined by the European Space Agency.;The schedule fitness - corresponding to the Hamming distance between mission requirements and generated schedule - are presented along with the execution time of each run. Algorithmic performance is discussed and put at the disposal of mission operations experts for consideration

Differences in parental feeding styles and practices and toddler eating behaviour across complementary feeding methods: Managing expectations through consideration of effect size

Nutritional experiences during infancy and toddlerhood influence the development of healthy eating habits later in life. Interest into solid food introduction practices has experienced resurgence due to the popularization of the baby-led weaning (BLW) approach as an alternative to more traditional parent-led weaning (PLW) practices. Although the literature shows beneficial effects of BLW on eating behaviours, the magnitude of those effects is unknown making parental expectation management challenging. This study provides an estimation of the size of the difference between the solid feeding practices groups for a variety of practices consistent with the development of healthy food preferences and behaviours.565 participants with infants between 12 and 36 months old completed a survey concerning their preferred parental feeding styles, parental feeding practices, sources of information on feeding and toddler's eating behaviour. Participants were categorised to one of four groups reflecting the level of infant self-feeding level a month after the introduction of solid food (Strict PLW, Predominant PLW, Predominant BLW and Strict BLW).Estimated effect sizes of the observed significant differences showed that the magnitude of effects was modest to minimal. Moderate effect sizes were observed in comparisons regarding breastfeeding duration, maternal feeding practices, sources of information and types of first food given to the infants at the beginning of solid feeding introduction. When it comes to toddlers’ eating behaviour and the family food environment, although some differences were statistically significant, the effect sizes were very small. Considering the long-lasting impact of food preferences developed at this stage along with the stress surrounding infant feeding decisions, it is crucial that the complementary feeding advice parents receive reflects realistic expectations of the outcomes regarding the effects on eating behaviour

Use of baby food products during the complementary feeding period: What factors drive parents' choice of products?

It is recommended that infants are introduced to complementary foods from 6 months old, moving from a solely milk diet to eating a family diet by 12 months old. Although home cooking of family foods is recommended, a rapidly growing market producing baby food products (BFP) such as jars, pouches and snacks has developed. These are often accompanied by marketing claims around nutritional, health and developmental impacts despite research highlighting high sugar content. Although numerous studies have explored drivers of infant formula choice and use, little research has examined the drivers of BFP use. This study used an online survey for United Kingdom parents of infants aged 4–12 months to explore use of BFP alongside perceptions and drivers to purchase products. Overall, 271 parents participated (173 used BFP and 98 did not), with a descriptive analysis of closed items and a thematic analysis for open ended text conducted. The top motivators for using BFP were convenience, time saving, and baby's perceived enjoyment of products. The most purchased puree was fruit based and the most purchased baby snacks were vegetable puffs/sticks, with snack purchases being more common than purees in this sample. Aspects such as perceived healthiness drove choice, with snack foods being seen to enhance self‐feeding skills, appetite regulation and motor development. Those who did not use BFP did not trust them and preferred to feed their baby home cooked foods. The findings are important for professionals working with parents, to support them through the transition to solid foods, particularly around raising awareness of marketing techniques and how to check content of foods to make a more informed choice

Ethical consumption: Identities, practices and potential to bring about social change

In recent decades, individuals as well as businesses – mainly those living and operating within advanced capitalist systems – have become increasingly aware of the social context of production and, thus, of the impact consumption has on the environment, animals and other fellow humans. Such reflexivity is echoed both in spheres of production (e.g. corporate social responsibility policies) and consumption (e.g. labelling schemes such as fair-trade and organic). Under these conditions the ‘ethical consumer’ was born. While, however, the concepts of ethical and political consumption have been around for some time now, our understanding of what it really means to be ‘ethical’ as a consumer today is still very fuzzy. In contrast with previous studies which ascribe a priori certain meanings and criteria to the ethical consumer concept, this study follows a bottom-up approach that provides space for individuals to express their own views on ethical consumption. To cater for a deeper understanding of the phenomenon under investigation, the research is designed as a case study within a specific geographical location; Partick, Glasgow. This study makes use of primary data generated through 20 in-depth interviews with self-identified ethical consumers, 10 interviews and 15 questionnaires with managers of grocery shops operating in the area, as well as 112 questionnaires completed by the public in a street survey. The findings challenge our conventional understanding of ‘ethics’ in the context of consumption; being ethical as a consumer extends beyond simply purchasing ethically marketed products and services, to include various lifestyle choices. Consumers raised concerns about the degree and nature of change that conventional ethical consumption can achieve. Utilising insights from this research, the study draws a conceptual distinction between the “ethical Shopper” (representing the side of ethical consumption that is hegemonically market-driven) and the “ethical Consumer” (representing its creative, pro-active, agency-driven counterpart). It is suggested that the latter allows consumption as a tool for social change to reach its full potential, since it escapes the fabricated ‘ethics’ of the market. Feeding back to the theoretical frameworks of ethical and political consumption, this study highlights the class and taste bias built into the (very expensive) idealized model of ethical lifestyle and, thus, calls for the inclusion of different types of consumer action such as downshifting, file-sharing, or even collective shoplifting, which have been –until now – neglected

The awarded young adult novel in Greece (1985-2004)

The purpose of this study was to examine the adolescent novels that were awarded in Greece from 1985 till 2005 by four major organizations. The primary focus was to outline the main characteristics of the awarded adolescent novel that developed during the last 20 years in Greece and secondly, to examine the main characteristics of those awarded novels so as to understand the importance of this newly formed genre and the important role it can play in the development of the adolescent. In the first part of the study we outlined the development and the main characteristics of the adolescent novel while we focused on the different criteria that are used by the four major organizations that award and promote this literary genre in Greece. The second part of the study analyzes the various stages of the buildingsroman as it’s seen through the themes of the novels, while a major component of it deals with the way the Greek identity is portrayed and promoted as well as the model of the adolescent hero. The study suggested that adolescence is the period between childhood and adulthood, during which the adolescent changes both biologically and psychologically and those changes are directly related to his/her future personality. The study also indicates that the adolescent novel describes that period that coincides with the final stages of the maturation of the teenager. Therefore, the adolescent readers identify themselves with the heroes, their emotions, and the various problems with references to the surrounding environment and the every day life. It was also suggested that the adolescent reader can discover a role model in the novel’s heroes and heroines which could lead to a self evaluation and an evaluation of the others around him, while at the same time he/she can enjoy the entertainment and aesthetic values of the novel

Personal relations and social media: The emotional experience on Instagram

Τα κοινωνικά δίκτυα όπως το Facebook και το Instagram αποτελούν πλέον έναν διαδικτυακό τόπο όπου τα άτομα σήμερα δημιουργούν και διατηρούν σχέσεις, κοινωνικοποιούνται και ανταλλάζουν κοινωνική ή άλλου είδους πληροφορία. Η παρούσα μελέτη εξερευνά την εμπειρία του Instagram και τις επιπτώσεις της στα συναισθήματα, το άγχος και σε μία σειρά από άλλες σχετικές μεταβλητές. Τα αποτελέσματα της ποσοτικής συσχετιστικής μεθόδου μέσω αυτοαναφοράς (n=289) ανέδειξαν την αδιαφορία ως το κύριο συναίσθημα που σχετίζεται με τη χρήση του Instagram γενικότερα, με την ευτυχία, την αγάπη και την περηφάνεια να υπερέχουν ελάχιστα μόνο στις περιπτώσεις εκείνες όπου η χρήση του Instagram ήταν θετικά προσωποποιημένη. Αναφορικά με το άγχος στο Instagram, βρέθηκε αρνητική συσχέτιση με την ηλικία, θετική συσχέτιση με το χρόνο χρήσης, ενώ δε βρέθηκαν διαφορές φύλου. Το άγχος στο Instagram βρέθηκε, επίσης, να παρουσιάζει συσχέτιση με την κοινωνική σύγκριση, την παθητική και ενεργητική χρήση καθώς επίσης και με την κοινωνική παρουσία, ευρήματα που καταδεικνύουν ότι το περιεχόμενο και το είδος της εμπλοκής είναι πιθανό να έχουν συναισθηματικές και ψυχολογικές επιπτώσεις. Βρέθηκε, επίσης, υψηλή συσχέτιση μεταξύ άγχους στο Instagram και προβληματικής χρήσης. Η αυτοεκτίμηση βρέθηκε να συσχετίζεται αρνητικά με το άγχος στο Instagram. Θετική σχέση συσχέτισης βρέθηκε μεταξύ κοινωνικής σύγκρισης και χρήσης, ενεργητικής η παθητικής. Τέλος, ο αριθμός των χρηστών που ακολουθεί ένα άτομο βρέθηκε να παίζει ρόλο στα επίπεδα του άγχους στο Instagram.Social network sites such as Facebook and Instagram have become an online venue where people nowadays form and maintain relationships, socialize and exchange social or other information. This study explores the Instagram experience and its effects on feelings, anxiety and a series of other related variables. Results of the self-report quantitative correlative method (n=289) revealed indifference as the primary feeling associated with Instagram use in general, slightly surpassed by happiness, love and pride only in cases when Instagram use was positively personalized. Regarding Instagram anxiety, results showed no sex differences, a negative correlation with age and a positive correlation with amount of use. Instagram anxiety was also found to correlate with social comparison, passive and active use as well as social presence, indicating that content and type of involvement is likely to have emotional and psychological effects. A high correlation was found between Instagram anxiety and problematic use. Self-esteem was found to correlate negatively with Instagram anxiety. A positive relationship was found between social comparison and use, active or passive. Finally, the number of users one follows was found to play a role in the amount of Instagram anxiety

Early feeding experiences, individual characteristics, and their impact on infant feeding outcomes.

Early life experiences impose long lasting effects on health and wellbeing. The early development of eating habits and flavour preferences associated with a healthy diet can help to extend and improve the quality of life. A variety of factors contribute to this process and the resulting early feeding choices have an impact on parents and infants alike. Initially, nutritional factors provide the key influence, with maternal diet affecting the flavour profile of amniotic fluid and breast milk. In doing so, these factors shape the type of flavours recognised as “familiar” and “safe” by the infant. Later parental behavioural inputs interact at different levels, and with an increasing influence, to further mould infants’ and toddlers’ eating related behaviours. This thesis aims to explore elements of the nutrition and behavioural inputs during early life by employing a bi-directional focus. In a small-scale laboratory study comparing vegetable acceptance between breast-fed and formula-fed infants it was found, contrary to hypotheses that the intake of vegetable puree did not vary with milk feeding type. Maternal ratings of their infant’s enjoyment of the vegetables were also comparable between the two groups. With the recognition that mothers likely use multiple means of assessing vegetable preference, the rationale for the enjoyment ratings applied was further explored. Two main categories of cues were derived ‘explicit cues’ and ‘implicit cues, with the first most commonly applied. Finally, the potential for mother-infant interactions to provide insight into vegetable acceptance was explored. Results suggested that mothers might adjust their interactions with their baby during feeding depending on the food familiarity. However, outcomes should be considered with caution due to various methodological limitations and the small sample size. The focus of subsequent research was guided by the methodological limitations identified in the laboratory based. The final online survey was targeted at weaning practices. Specifically, it demonstrated positive associations between the baby-led weaning approach and the use of health promoting parental feeding practices to achieve positive eating behaviour outcomes in toddlers. Although results were encouraging, as BLW is relatively contemporary in the literature, further research is required to explore the long-term benefits of this weaning method