Academic literature on the topic 'Sailor (Computer network)'

Abstract The weather has a major impact on the profitability, safety, and environmental sustainability of the routes sailed by seagoing vessels. The prevailing weather strongly influences the course of routes, affecting not only the safety of the crew, but also the fuel consumption and therefore the emissions of the vessel. Effective decision support is required to plan the route and the speed of the vessel considering the forecasted weather. We implement a genetic algorithm to minimize the fuel consumption of a vessel taking into account the two most important influences of weather on a ship: the wind and the waves. Our approach assists route planners in finding cost minimal routes that consider the weather, avoid specified areas, and meet arrival time constraints. Furthermore, it supports ship speed control to avoid areas with weather conditions that would result in high fuel costs or risk the safety of the vessel. The algorithm is evaluated for a variety of instances to show the impact of weather routing on the routes and the fuel and travel time savings that can be achieved with our approach. Including weather into the routing leads to a savings potential of over 10% of the fuel consumption. We show that ignoring the weather when constructing routes can lead to routes that cannot be sailed in practice. Furthermore, we evaluate our algorithm with stochastic weather data to show that it can provide high-quality routes under real conditions even with uncertain weather forecasts.

In a recent gaming anthology, Henry Jenkins cannot help contrasting his son's cramped, urban, media-saturated existence with his own idyllic, semi-rural childhood. After describing his own Huck Finn meanderings over "the spaces of my boyhood" including the imaginary kingdoms of Jungleoca and Freedonia, Jenkins relates his version of his son's experiences: My son, Henry, now 16 has never had a backyard He has grown up in various apartment complexes, surrounded by asphalt parking lots with, perhaps, a small grass buffer from the street… Once or twice, when I became exasperated by my son's constant presence around the house I would … tell him he should go out and play. He would look at me with confusion and ask, where? … Who wouldn't want to trade in the confinement of your room for the immersion promised by today's video games? … Perhaps my son finds in his video games what I found in the woods behind the school, on my bike whizzing down the hills of suburban backstreets, or settled into my treehouse with a good adventure novel intensity of experience, escape from adult regulation; in short, "complete freedom of movement". (Jenkins 1998, 263-265) Games here are connected with a shrinking availability of domestic and public space, and a highly mediated experience of the world. Despite his best intentions, creeping into Jenkins's piece is a sense that games act as a poor substitute for the natural spaces of a "healthy" childhood. Although "Video games did not make backyard play spaces disappear", they "offer children some way to respond to domestic confinement" (Jenkins 1998, 266). They emerge, then, as a palliation for the claustrophobic circumstances of contemporary urban life, though they offer only unreal spaces, replete with "lakes of fire … cities in the clouds … [and] dazzling neon-lit Asian marketplaces" (Jenkins 1998, 263), where the work of the childish imagination is already done. Despite Jenkins's assertion that games do offer "complete freedom of movement", it is hard to shake the feeling that he considers his own childhood far richer in exploratory and imaginative opportunities: Let me be clear I am not arguing that video games are as good for kids as the physical spaces of backyard play culture. As a father, I wish that my son would come home covered in mud or with scraped knees rather than carpet burns ... The psychological and social functions of playing outside are as significant as the impact of "sunshine and good exercise" upon our physical well-being. (Jenkins 1998, 266) Throughout the piece, games are framed by a romantic, anti-urban discourse: the expanding city is imagined as engulfing space and perhaps destroying childhood itself, such that "'sacred' places are now occupied by concrete, bricks or asphalt" (Jenkins 1998, 263). Games are complicit in this alienation of space and experience. If this is not quite Paul Virilio's recent dour contention that modern mass media forms work mainly to immobilise the body of the consumer--Virilio, luckily, has managed to escape the body-snatchers--games here are produced as a feeble response to an already-effected urban imprisonment of the young. Strikingly, Jenkins seems concerned about his son's "unhealthy" confinement to private, domestic space, and his inability to imaginatively possess a slice of the world outside. Jenkins's description of his son's confinement to the world of "carpet burns" rather than the great outdoors of "scraped knees" and "mud" implicitly leaves the distinction between domestic and public, internal and external, and even the imagined passivity of the domestic sphere as against the activity of the public intact. For those of us who see games as productive activities, which generate particular, unique kinds of pleasure in their own right, rather than as anaemic replacements for lost spaces, this seems to reduce a central cultural form. For those of us who have at least some sympathy with writers on the urban environment like Raban (1974) and Young (1990), who see the city's theatrical and erotic possibilities, Jenkins's fears might seem to erase the pleasures and opportunities that city life provides. Rather than seeing gamers and children (the two groups only partially overlap) as unwitting agents in their own confinement, we can arrive at a slightly more complex view of the relationship between games and urban space. By looking at the video games arcade as it is situated in urban retail space, we can see how gameplay simultaneously acts to regulate urban space, mediates a unique kind of urban performance, and allows sophisticated representations, manipulations and appropriations of differently conceived urban spaces. Despite being a long-standing feature of the urban and retail environment, and despite also being a key site for the "exhibition" of a by-now central media form, the video game arcade has a surprisingly small literature devoted to it. Its prehistory in pinball arcades and pachinko parlours has been noted (by, for example, Steven Poole 2000) but seldom deeply explored, and its relations with a wider urban space have been given no real attention at all. The arcade's complexity, both in terms of its positioning and functions, may contribute to this. The arcade is a space of conflicting, contradictory uses and tendencies, though this is precisely what makes it as important a space as the cinema or penny theatre before it. Let me explain why I think so. The arcade is always simultaneously a part of and apart from the retail centres to which it tends to attach itself.1 If it is part of a suburban shopping mall, it is often located on the ground floor near the entrance, or is semi-detached as cinema complexes often are, so that the player has to leave the mall's main building to get there, or never enter. If it is part of a city or high street shopping area, it is often in a side street or a street parallel to the main retail thoroughfare, or requires the player to mount a set of stairs into an off-street arcade. At other times the arcade is located in a space more strongly marked as liminal in relation to the city -- the seaside resort, sideshow alley or within the fences of a theme park. Despite this, the videogame arcade's interior is usually wholly or mostly visible from the street, arcade or thoroughfare that it faces, whether this visibility is effected by means of glass walls, a front window or a fully retractable sliding door. This slight distance from the mainstream of retail activity and the visibility of the arcade's interior are in part related to the economics of the arcade industry. Arcade machines involve relatively low margins -- witness the industry's recent feting and embrace of redemption (i.e. low-level gambling) games that offer slightly higher turnovers -- and are hungry for space. At the same time, arcades are dependent on street traffic, relentless technological novelty and their de facto use as gathering space to keep the coins rolling in. A balance must be found between affordability, access and visibility, hence their positioning at a slight remove from areas of high retail traffic. The story becomes more complicated, though, when we remember that arcades are heavily marked as deviant, disreputable spaces, whether in the media, government reports or in sociological and psychological literature. As a visible, public, urban space where young people are seen to mix with one another and unfamiliar and novel technologies, the arcade is bound to give rise to adult anxieties. As John Springhall (1998) puts it: More recent youth leisure… occupies visible public space, is seen as hedonistic and presents problems within the dominant discourse of 'enlightenment' … [T]he most popular forms of entertainment among the young at any given historical moment tend also to provide the focus of the most intense social concern. A new medium with mass appeal, and with a technology best understood by the young… almost invariably attracts a desire for adult or government control (160-161, emphasis mine) Where discourses of deviant youth have also been employed in extending the surveillance and policing of retail space, it is unsurprising that spaces seen as points for the concentration of such deviance will be forced away from the main retail thoroughfares, in the process effecting a particular kind of confinement, and opportunity for surveillance. Michel Foucault writes, in Discipline and Punish, about the classical age's refinements of methods for distributing and articulating bodies, and the replacement of spectacular punishment with the crafting of "docile bodies". Though historical circumstances have changed, we can see arcades as disciplinary spaces that reflect aspects of those that Foucault describes. The efficiency of arcade games in distributing bodies in rows, and side by side demonstrates that" even if the compartments it assigns become purely ideal, the disciplinary space is always, basically, cellular" (Foucault 1977, 143). The efficiency of games from Pong (Atari:1972) to Percussion Freaks (Konami: 1999) in articulating bodies in play, in demanding specific and often spectacular bodily movements and competencies means that "over the whole surface of contact between the body and the object it handles, power is introduced, fastening them to one another. It constitutes a body weapon, body-tool, body-machine complex" (Foucault 1977,153). What is extraordinary is the extent to which the articulation of bodies proceeds only through a direct engagement with the game. Pong's instructions famously read only "avoid missing ball for high score"--a whole economy of movement, arising from this effort, is condensed into six words. The distribution and articulation of bodies also entails a confinement in the space of the arcade, away from the main areas of retail trade, and renders occupants easily observable from the exterior. We can see that games keep kids off the streets. On the other hand, the same games mediate spectacular forms of urban performance and allow particular kinds of reoccupation of urban space. Games descended or spun off from Dance Dance Revolution (Konami: 1998) require players to dance, in time with thumping (if occasionally cheesy) techno, and in accordance with on-screen instructions, in more and more complex sequences on lit footpads. These games occupy a lot of space, and the newest instalment (DDR has just issued its "7th Mix") is often installed at the front of street level arcades. When played with flair, games such as these are apt to attract a crowd of onlookers to gather, not only inside, but also on the footpath outside. Indeed games such as these have given rise to websites like http://www.dancegames.com/au which tells fans not only when and where new games are arriving, but whether or not the positioning of arcades and games within them will enable a player to attract attention to their performance. This mediation of cyborg performance and display -- where success both achieves and exceeds perfect integration with a machine in urban space -- is particularly important to Asian-Australian youth subcultures, which are often marginalised in other forums for youthful display, like competitive sport. International dance gamer websites like Jason Ho's http://www.ddrstyle.com , which is emblazoned with the slogan "Asian Pride", explicitly make the connection between Asian youth subcultures and these new kinds of public performance. Games like those in the Time Crisis series, which may seem less innocuous, might be seen as effecting important inversions in the representation of urban space. Initially Time Crisis, which puts a gun in the player's hand and requires them to shoot at human figures on screen, might even be seen to live up to the dire claims made by figures like Dave Grossman that such games effectively train perpetrators of public violence (Grossman 1995). What we need to keep in mind, though, is that first, as "cops", players are asked to restore order to a representation of urban space, and second, that that they are reacting to images of criminality. When criminality and youth are so often closely linked in public discourse (not to mention criminality and Asian ethnicity) these games stage a reversal whereby the young player is responsible for performing a reordering of the unruly city. In a context where the ideology of privacy has progressively marked public space as risky and threatening,2 games like Time Crisis allow, within urban space, a performance aimed at the resolution of risk and danger in a representation of the urban which nevertheless involves and incorporates the material spaces that it is embedded in.This is a different kind of performance to DDR, involving different kinds of image and bodily attitude, that nevertheless articulates itself on the space of the arcade, a space which suddenly looks more complex and productive. The manifest complexity of the arcade as a site in relation to the urban environment -- both regulating space and allowing spectacular and sophisticated types of public performance -- means that we need to discard simplistic stories about games providing surrogate spaces. We reify game imagery wherever we see it as a space apart from the material spaces and bodies with which gaming is always involved. We also need to adopt a more complex attitude to urban space and its possibilities than any narrative of loss can encompass. The abandonment of such narratives will contribute to a position where we can recognise the difference between the older and younger Henrys' activities, and still see them as having a similar complexity and richness. With work and luck, we might also arrive at a material organisation of society where such differing spaces of play -- seen now by some as mutually exclusive -- are more easily available as choices for everyone. NOTES 1 Given the almost total absence of any spatial study of arcades, my observations here are based on my own experience of arcades in the urban environment. Many of my comments are derived from Brisbane, regional Queensland and urban-Australian arcades this is where I live but I have observed the same tendencies in many other urban environments. Even where the range of services and technologies in the arcades are different in Madrid and Lisbon they serve espresso and alcohol (!), in Saigon they often consist of a bank of TVs equipped with pirated PlayStation games which are hired by the hour their location (slightly to one side of major retail areas) and their openness to the street are maintained. 2 See Spigel, Lynn (2001) for an account of the effects and transformations of the ideology of privacy in relation to media forms. See Furedi, Frank (1997) and Douglas, Mary (1992) for accounts of the contemporary discourse of risk and its effects. References Douglas, M. (1992) Risk and Blame: Essays in Cultural Theory. London ; New York : Routledge. Foucault, M. (1979) Discipline and Punish: The Birth of the Prison. Trans. Alan Sheridan. Harmondsworth, England: Penguin,. Furedi, F.(1997) Culture of Fear: Risk-taking and the Morality of Low Expectation. London ; Washington : Cassell. Grossman, D. (1995) On Killing: The Psychological Cost of Learning to Kill in War and Society. Boston: Little, Brown. Jenkins, H. (1998) Complete freedom of movement: video games as gendered play spaces. In Jenkins, Henry and Justine Cassell (eds) From Barbie to Mortal Kombat : Gender and Computer Games. Cambridge, Mass.: MIT Press. Poole, S. (2000) Trigger Happy: The Inner Life of Videogames. London: Fourth Estate. Raban, J. (1974) Soft City. London: Hamilton. Spigel, L. (2001) Welcome to the Dreamhouse: Popular Media and the Postwar Suburbs. Durham and London: Duke University Press. Springhall, J. (1998) Youth, Popular Culture and Moral Panics : Penny Gaffs to Gangsta-rap, 1830-1996. New York: St. Martin's Press. Young, I.M. (1990) Justice and the Politics of Difference. Princeton, NJ: Princeton University Press. Websites http://www.yesterdayland.com/popopedia/s... (Time Crisis synopsis and shots) http://www.dancegames.com/au (Site for a network of fans revealing something about the culture around dancing games) http://www.ddrstyle.com (website of Jason Ho, who connects his dance game performances with pride in his Asian identity). http://www.pong-story.com (The story of Pong, the very first arcade game) Games Dance Dance Revolution, Konami: 1998. Percussion Freaks, Konami: 1999. Pong, Atari: 1972. Time Crisis, Namco: 1996. Links http://www.dancegames.com/au http://www.yesterdayland.com/popopedia/shows/arcade/ag1154.php http://www.pong-story.com http://www.ddrstyle.com Citation reference for this article MLA Style Wilson, Jason A.. "Performance, anxiety" M/C: A Journal of Media and Culture 5.2 (2002). [your date of access] < http://www.media-culture.org.au/0205/performance.php>. Chicago Style Wilson, Jason A., "Performance, anxiety" M/C: A Journal of Media and Culture 5, no. 2 (2002), < http://www.media-culture.org.au/0205/performance.php> ([your date of access]). APA Style Wilson, Jason A.. (2002) Performance, anxiety. M/C: A Journal of Media and Culture 5(2). < http://www.media-culture.org.au/0205/performance.php> ([your date of access]).

A coupled aerodynamic/structures approach is presented for predicting the flying shape and performance of yacht sails in upwind conditions. The method is incorporated in a flow simulation computer program, and is part of an ultimate objective for a simultaneous aeroelastic/hydro analysis in a Dynamic Velocity Prediction Program (DVPP), that will include a 6DOF motion solver, and at some point could include calculations in waves. The time-stepping aerodynamic module uses an advanced vortex lattice method for the sails and a panel method with special base separation treatment to represent the abovewater part of the hull and mast. A coupled inverse boundary layer analysis is applied on all surfaces including both sides of each sail membrane; this computes the skinfriction drag and the source displacement effects of the boundary layers and wakes, including bubble and leeside “trailing-edge” type separations. . At each step, the computed aerodynamic pressure and skin-friction loads are transferred to a coupled structures module that uses a network grid of tension “cords” in each sail membrane, each cord representing a collection of fiber “strings”. The solution of a structural equilibrium matrix provides the displacements needed to achieve balance between the aerodynamic and tension loads at each grid point as the shape iterations proceed. Details of the methodology used are presented and comparisons of predicted aerodynamic forces to wind tunnel results and an existing VPP sail model are provided. In addition, predictions are compared to some simple experiments to demonstrate the aerodynamic/structural coupling necessary to predict flying shape. Finally, an outline is given for incorporation of this methodology into the planned Dynamic Velocity Prediction Program.

Yacht races are won by good sailors racing fast boats. A good skipper takes decisions at key moments of the race based on the anticipated wind behavior and on his position on the racing area and with respect to the competitors. His aim is generally to complete the race before all his opponents, or, when this is not possible, to perform better than some of them. In the past two decades some methods have been proposed to compute optimal strategies for a yacht race. Those strategies are aimed at minimizing the expected time needed to complete the race and are based on the assumption that the faster a yacht, the higher the number of races that it will win (and opponents that it will defeat). In a match race, however, only two yachts are competing. A skipper’s aim is therefore to complete the race before his opponent rather than completing the race in the shortest possible time. This means that being on average faster may not necessarily mean winning the majority of races. This papers present the development of software to compute a sailing strategy for a match race that can defeat an opponent who is following a fixed strategy that minimizes the expected time of completion of the race. The proposed method includes two novel aspects in the strategy computation: A short-term wind forecast, based on an Artificial Neural Network (ANN) model, is performed in real time during the race using the wind measurements collected on board. Depending on the relative position with respect to the opponent, decisions with different levels of risk aversion are computed. The risk attitude is modeled using Coherent Risk Measures. The software is tested in a number of simulated races. The results confirm that maximizing the probability of winning a match race does not necessarily correspond to minimizing the expected time needed to complete the race.