1,721,076 research outputs found
Drone swarms in fire suppression activities: A conceptual framework
No full textThe recent huge technological development of unmanned aerial vehicles (UAVs) can provide breakthrough means of fighting wildland fires. We propose an innovative forest firefighting system based on the use of a swarm of hundreds of UAVs able to generate a continuous flow of extinguishing liquid on the fire front, simulating the effect of rain. Automatic battery replacement and extinguishing liquid refill ensure the continuity of the action. We illustrate the validity of the approach in Mediterranean scrub first computing the critical water flow rate according to the main factors involved in the evolution of a fire, then estimating the number of linear meters of active fire front that can be extinguished depending on the number of drones available and the amount of extinguishing fluid carried. A fire propagation cellular automata model is also employed to study the evolution of the fire. Simulation results suggest that the proposed system can provide the flow of water required to fight low-intensity and limited extent fires or to support current forest firefighting techniques
Model Predictive Control for the Scheduling of Seedings in an Adaptive Vertical Farm
No full textA model predictive control approach is presented for the scheduling of sowings in an adaptive vertical farm, i.e., an innovative vertical greenhouse in which the spacing between shelves is automatically adapted to crop growth. First, a dynamic model describing the evolution of occupancy and shelf height is developed. The model is affected by disturbances to account for possible deviations of crop growth from the nominal pattern. Then, an optimal control problem over a given timeframe is defined to determine the best time instants to perform seedings in the various shelves with the goal of maximizing production yield. The repeated solution of the optimal control problem over a shorter, moving window over time, according to the receding horizon paradigm, allows to devise robust control strategies with respect to disturbances, even in the absence of predictions about their future realizations. Preliminary simulation results are reported for different control horizons and type of disturbances to showcase the effectiveness of the proposed approach in maximizing production yield while exploiting almost all the available vertical space
Mixed-Integer Linear Programming for the Scheduling of Seedings in an Industrial Adaptive Vertical Farm
No full textWe present a new concept of industrial vertical greenhouse, called adaptive vertical farm, based on the possibility of adapting the distance between the shelves to the growth of the plants cultivated therein. This is possible through a set of sensors able to measure the crop height and a set of actuators to automatically move the shelves. A scheduling approach of seedings is proposed that requires the solution of a mixed-integer linear programming problem to fully utilize all the available vertical space and maximize the production yield. Simulation results obtained when cultivating various types of crops and for different greenhouse configurations in terms of total height and number of shelves are reported. The goal is to evaluate the effectiveness of the proposed scheduling approach and of the adaptive vertical farm concept in general, as compared to a vertical farm with fixed shelves
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Adaptive Vertical Farm for Fresh Food Production in Orbital Stations and Future Lunar Settlements
No full textWe propose an adaptive vertical farm that can be installed in orbital stations and future lunar settlements to produce fresh food for astronauts. Such an innovative greenhouse is based on the idea of progressively adapting the height of the various shelves to the growth of the plants, instead of fixing the height of the shelves to the maximum growth, as commonly done in the case of vertical farms with fixed shelves. The main advantages are the need of conditioning a reduced space as compared to fixed-shelves installations, thus resulting in a reduced energy consumption per unit of production, and the increase of the overall production owing to the possibility of installing a larger number of shelves in the same vertical space. The full efficiency of the proposed adaptive vertical farm requires an optimal scheduling of sowings, for which a mixedinteger linear programming problem is devised with the aim of maximizing the number of seedings, while fully exploiting the total height of the greenhouse. Numerical results in comparisons with a vertical farm with fixed shelves showcase the effectiveness of the proposed ideas
The Adaptive Vertical Farm as an Efficient Tool for the Cultivation of Multiple Crops in Space
No full textThe adaptive vertical farm is proposed to produce a variety of fresh food for astronauts during missions or future space installations. It is an innovative vertical greenhouse that relies on the idea of gradually adjusting the distance between the shelves moving them automatically according to the growth of the plants. We refer to this concept as adaptive principle. In more detail, an optimal scheduling algorithm of sowings is presented for the cultivation of two types of crops using mixed-integer linear programming to fully exploit the available vertical space and maximize the production yield. Numerical results are reported in a case study involving the cultivation of wheat and lettuce to showcase the effectiveness of the approach in comparison with a vertical farm with fixed shelves
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