Contextual Trajectories Research Articles

Bidirectional Long Short-Term Memory Development for Aircraft Trajectory Prediction Applications to the UAS-S4 Ehécatl

The rapid advancement of unmanned aerial systems in various civilian roles necessitates improved safety measures during their operation. A key aspect of enhancing safety is effective collision avoidance, which is based on conflict detection and is greatly aided by accurate trajectory prediction. This paper represents a novel data-driven trajectory prediction methodology based on applying the Long Short-Term Memory (LSTM) prediction algorithm to the UAS-S4 Ehécatl. An LSTM model was designed as the baseline and then developed into a Staked LSTM to better capture complex and hierarchical temporal trajectory patterns. Next, the Bidirectional LSTM was developed for a better understanding of the contextual trajectories from both its past and future data points, and to provide a more comprehensive temporal perspective that could enhance its accuracy. LSTM-based models were evaluated in terms of mean absolute percentage errors. The results reveal the superiority of the Bidirectional LSTM, as it could predict UAS-S4 trajectories more accurately than the Stacked LSTM. Moreover, the developed Bidirectional LSTM was compared with other state-of-the-art deep neural networks aimed at aircraft trajectory prediction. Promising results confirmed that Bidirectional LSTM exhibits the most stable MAPE across all prediction horizons.

Progressive Contextual Trajectory Prediction with Adaptive Gating and Fuzzy Logic Integration

Progressive Contextual Trajectory Prediction with Adaptive Gating and Fuzzy Logic Integration

Same but different: The latency of a shared expectation signal interacts with stimulus attributes

Predictive coding theories assert that perceptual inference is a hierarchical process of belief updating, wherein the onset of unexpected sensory data causes so-called prediction error responses that calibrate erroneous inferences. Given the functionally specialised organisation of visual cortex, it is assumed that prediction error propagation interacts with the specific visual attribute violating an expectation. We sought to test this within the temporal domain by applying time-resolved decoding methods to electroencephalography (EEG) data evoked by contextual trajectory violations of either brightness, size, or orientation within a bound stimulus. We found that following ∼170 ms post stimulus onset, responses to both size violations and orientation violations were decodable from physically identical control trials in which no attributes were violated. These two violation types were then directly compared, with attribute-specific signalling being decoded from 265 ms. Temporal generalisation suggested that this dissociation was driven by latency shifts in shared expectation signalling between the two conditions. Using a novel temporal bias method, we then found that this shared signalling occurred earlier for size violations than orientation violations. To our knowledge, we are among the first to decode expectation violations in humans using EEG and have demonstrated a temporal dissociation in attribute-specific expectancy violations.

Juventudes, patrimônio disposicional e aprendizagem situada: proposição de um modelo teórico para pesquisas

Abstract This theoretical essay links the discussion between popular media, dispositional heritage, and situated learning, proposing a theoretical model for future research. It is suggested that the dispositional heritage of young people from popular backgrounds (inclinations, behaviors, and social practices) is forged from individual and contextual trajectories and implies the process of situated learning and socialization. The proposal contributes to understanding youth from a sociological perspective and social practices, unlike research conducted within the administration mainstream, which tends to focus on professional training and the insertion of young people into the job market based on organizational behavior. After connecting the concepts, a theoretical model is suggested that can guide empirical studies. Finally, some possibilities for conducting this research are presented.

Attention and prediction modulations in expected and unexpected visuospatial trajectories.

Humans are constantly exposed to a rich tapestry of visual information in a potentially changing environment. To cope with the computational burden this engenders, our perceptual system must use prior context to simultaneously prioritise stimuli of importance and suppress irrelevant surroundings. This study investigated the influence of prediction and attention in visual perception by investigating event-related potentials (ERPs) often associated with these processes, N170 and N2pc for prediction and attention, respectively. A contextual trajectory paradigm was used which violated visual predictions and neglected to predetermine areas of spatial interest, to account for the potentially unpredictable nature of a real-life visual scene. Participants (N = 36) viewed a visual display of cued and non-cued shapes rotating in a five-step predictable trajectory, with the fifth and final position of either the cued or non-cued shape occurring in a predictable or unpredictable spatial location. To investigate the predictive coding theory of attention we used factors of attention and prediction, whereby attention was manipulated as either cued or non-cued conditions, and prediction manipulated in either predictable or unpredictable conditions. Results showed both enhanced N170 and N2pc amplitudes to unpredictable compared to predictable stimuli. Stimulus cueing status also increased N170 amplitude, but this did not interact with stimulus predictability. The N2pc amplitude was not affected by stimulus cueing status. In accordance with previous research these results suggest the N170 is in part a visual prediction error response with respect to higher-level visual processes, and furthermore the N2pc may index attention reorientation. The results demonstrate prior context influences the sensitivity of the N170 and N2pc electrophysiological responses. These findings add further support to the role of N170 as a prediction error signal and suggest that the N2pc may reflect attentional reorientation in response to unpredicted stimulus locations.

Evaluating Spatio-temporal Data Models for Trajectories in PostGIS Databases

Research in transport, ecology, health and other fields stands to profit from an improved understanding of movement. As movement data availability improves, the need for appropriate movement data analysis increases. However, the limited support for modelling moving objects in GIS hampers data exploration and analysis. This paper discusses trajectory data models and their implementation in the open-source spatial database system PostGIS. We quantify the difference in performance between PostGIS default trajectory support, dedicated trajectory data models, and commonly used point-based data models. To the best of our knowledge, this is the first paper to evaluate PostGIS default trajectory support and compare it to a proposed dedicated trajectory data type from the literature. Our experiments include computing trajectory duration and length, temporal and spatial filters, extracting positions at a certain time, and visualizing trajectories in desktop GIS. We also discuss the limitations of, and potential for, contextual trajectories and moving area object trajectories. Our results show that PostGIS functions for moving point object trajectories are fast, reduce query complexity, and provide good indexing integration, especially concerning multi-dimensional indices; the results also reveal that trajectory data models outperform commonly used point-based data models.

Social enterprise in Rwanda: an overview

PurposeThe purpose of this paper is to analyze the context, the concept and the main types of social enterprises in Rwanda, and to present its main institutional and contextual trajectories.Design/methodology/approachThe author carried out a literature review and interviews. Six categories were identified; each one is illustrated by one emblematic case.FindingsThe paper presents the evolution of economically oriented social organizations in Rwanda, mostly under the form of cooperatives and NGOs and with inspiration from traditional forms of mutual help. The context of emergence of social enterprise in Rwanda was shaped, among other factors, by Anglo-Saxon influence. Other factors include notably the aftermath of the 1994 genocide against Tutsi, the current governance prevailing in the country and the current entrepreneurships trends. The paper also underlines the absence of research on the subject in Rwanda. Six categories of social enterprises in Rwanda and their main features have been identified and analyzed, namely, NGOs, cooperatives, informal organizations, social entrepreneurs, public/private partnerships and companies carrying out social activities. Finally, the paper analyzes the institutional and contextual trajectories of social enterprise in Rwanda.Originality/valueThe paper explores and provides insights into the specificities and the current trends of social enterprise in Rwanda with a view to fostering further analysis for several research avenues.

The Activity of “Writing for Learning” in a Nursing Program.

This article explores the activity of writing in higher education as a mediational means for student meaning making. From a dialogic perspective, writing is not about learning and applying formulas and making fixed kinds of texts, but about ways of working and ways of acting that brings writers, readers, resources and contexts into trajectories. The argument is that processes of writing enhance student meaning making and that these processes are formed by complex interaction. Contextual interpretation and use of mediational means is constituted in social systems of activities that depend on and promote particular kinds of texts. We need insights in contextual trajectories to understand the relationship between writing and student meaning making. Empirically, I draw on a study investigating portfolio writing as a pedagogical tool in a nursing program in Norway. The rationale of the study was an identified need for information about how processes of writing develop, how texts come into being and how institutional tasks of writing are being unpacked. The aim of the paper is to explore a dialogical approach to the activity of writing and to discuss possible methodological implications from the theoretical framework. The empirical study is used as an illustration

Children of War and Peace

Political conflicts and intractable wars can be conceived as disasters of human activities and they affect the entire life of children and their families. An ecological-transactional perspective of human development is adopted in order to identify multilevel developmental and contextual trajectories that might facilitate or impede the willingness and readiness of people to engage openly and flexibly in conflict-resolution paradigms. It is proposed that building early trustful relationships at the interpersonal level is likely to enhance one’s willingness and ability to explore the other side’s goals in the conflict, and ultimately to consider reconciliation. At the same time, the absence of such trustful relationships is likely to induce more rigid and one-sided approaches in adulthood. Toward that end, the Palestinian–Israeli conflict serves as the main context of analysis.

Coordination of innovation policies in the catching-up context: a historical perspective on Estonia and Brazil

This paper highlights some of the crucial weaknesses of innovation- policy-research that limit the relevance of this research for policy-making practices in catching-up countries. The paper proposes a framework that takes a multi-level and dynamic approach towards studying innovation-policy-making processes. This framework is applied herein to examine the evolution of innovation policy and governance trajectories of Estonia and Brazil and how this has affected the capacities for technological accumulation and development. The paper argues that crucial aspects of these contextual trajectories are being overlooked by standard innovation policy and governance analyses. In terms of policy implications, the paper concludes that the increasing influence of external pressures on innovation policy trajectories of catching-up countries is only reinforcing the use of narrow analytical perspectives and threatens to further de-contextualise innovation-policy-making in these countries. The spread of 'participatory' or 'networked' innovation policy models is presented as an example of these tendencies. Reference to this paper should be made as follows: Karo, E. and Kattel, R. (2010) 'Coordination of innovation policies in the catching-up context: a historical perspective on Estonia and Brazil', Int. J. Technological Learning, Innovation and Development, Vol. 3, No. 4, pp.293-329.

Non-government organisations and the dialectics of state and civil society

This paper is concerned with envisioning the development of non-government organisations (NGOs) in Australia over the next 200 years. It begins with a discussion of a hypothetical NGO, providing vignettes of its activities in 2104 and 2204, and sketching out contextual factors that might influence NGO development. This discussion is followed by an outline of the methodology upon which the projections indicated in the hypothetical case-study are based. Three methodological approaches are used. The first approach begins from an analysis of current contextual trajectories, and projects the role of NGOs within these trajectories. The second approach postulates that the changes that will occur will be affected by the reflexive nature of social change, involving continual reflection and action. The third methodological approach draws on this notion of reflexivity, but emphasises that social change is not only a reflexive process, it is also a dialectical one. The dialectical approach rests on the premise that change occurs through a process of the accumulation of contradictions, challenge and resolution. Using these methodological approaches the paper proceeds to identify three factors which will influence the Australian NGO sector in the next 200 years. These factors are the shifting relations between the state and civil society, including the rise of the neo-authoritarian state in the 21st century; the ways in which least advantaged people are dealt with and, finally, the idea of risk society. While it is more difficult to identify the contextual and NGO trajectories into the 22nd and 23rd centuries, the paper postulates a more utopian vision for NGOs in Australia in 200 years time, where the category of people who had been previously marginalised disappears, and the major roles of NGOs are to ensure cultural diversity and develop civil labour.