236,407 research outputs found
Modelling and control of a variable-speed switched reluctance generator based wind turbine
No full textThis paper studies the system modelling and control aspects of switched reluctance generator (SRG) based variable speed wind turbines. A control system is implemented to provide proper operation of the SRG as well as power tracking capabilities for varying wind speeds. The control system for the grid side inverter that will allow the SRG to properly generate power to the system is also presented. Studies are presented of both the SRG and inverter control systems capabilities during a balanced three-phase fault. The paper will demonstrate that the SRG based wind turbine presents a feasible variable wind speed solution with good fault response capabilities
Simulating Speed in Language: Contributions from vision, audition and action
No full textEmbodied theories propose that understanding meaning in language requires the mental simulation of entities being referred to. These mental simulations would make use of the same modality-specific systems involved in perceiving and acting upon such entities in the world, grounding language in the real world. However, embodied theories are currently underspecified in terms of how much information from an event is contained in mental simulations, and what features of experience are included. The thesis addresses comprehension of language that describes speed of events. Investigating speed allows embodied theories to be extended to a more complex feature of events. Further, speed is a fine-grained feature and thus testing an embodied theory of speed will reveal whether or not mental simulations include the fine details of real-world experience. Within the thesis four main methods of investigation were used, assessing simulation of speed with different types of speed language under different conditions: behavioural testing combining speed in language with speed in perception and action, eye-tracking investigating whether eye-movements to a visual scene are affected by speed in sentences, a psychophysics paradigm assessing whether speed in language affects visual perception processes, and finally, as a crucial test of embodiment, whether or not Parkinson’s patients, who have difficulty moving speedily, also have problems with comprehension of speed language. The main findings of the thesis are that: (1) speed, a fine-grained and abstract dimension, is simulated during comprehension, (2) simulations are dynamic and context-dependent, and (3) simulations of speed are specific to biological motion and can encode specific effectors used in an action.
These results help to specify current embodied theories in terms of what the nature of simulations are and what factors they are sensitive to, in addition to broadly providing support for the sharing of cognitive/neural processes between language, action and perception
Galileo's Refutation of the Speed-Distance Law of Fall Rehabilitated
No full textGalileo's refutation of the speed-distance law of fall in his Two New Sciences is routinely dismissed as a moment of confused argumentation. We urge that Galileo's argument correctly identified why the speed-distance law is untenable, failing only in its very last step. Using an ingenious combination of scaling and self-similarity arguments, Galileo found correctly that bodies, falling from rest according to this law, fall all distances in equal times. What he failed to recognize in the last step is that this time is infinite, the result of an exponential dependence of distance on time. Instead, Galileo conflated it with the other motion that satisfies this ‘equal time’ property, instantaneous motion
Speed and income
No full textThe relationship between speed and income is established in a micro- economic model focusing on the trade-off between travel time and the risk of receiving a penalty for exceeding the speed limit. This is used to determine when a rational driver will choose to exceed the speed limit. The relationship between speed and income is found again in the empirical analysis of a cross-sectional dataset comprising 60.000 observations of car trips. This is utilised to perform regressions of speed on income, distance travelled and a number of controls. The results are clearly significant and indicate an average income elasticity of speed of 0.03; it is smaller at short distances and about twice as large at the longest distance investigated of 200 km.Speed, income
Automating the determination of wave speed using the pu-loop method
No full textThe PU-loop (pressure-velocity loop) is a method for determining wave speed and relies on the linear relationship between the pressure and velocity in the absence of reflected waves. This linearity of the PU-loop during early systole, which is directly related to wave speed, has always been established by eye. This paper presents a new technique that establishes this linearity and thus determining wave speed online. Pressure and flow were measured in the ascending aorta of 11 anesthetised dogs. The slope of the PU-loop, indicating wave speed was determined by eye and by using the new technique. The difference between the slopes of the two methods is in the order of 3%. The new technique is convenient and allows for the online assessment of wave speed, which could be used as a bedside tool for the assessment of arterial compliance
Speed Choice, Speed Preference and Risk Perception: Relevance for the Problem of Speed Variability in Traffic
No full textFifty percent of drives have been found to frequently violate speed limits (OECD/ECMT, 2006), and speed limit compliance appears to depend on the perceived credibility of a road’s speed limit (Goldenbeld & van Schagen, 2007). Credibility of speed limits, in turn, appears to be determined by the match between drivers’ speed preferences and the design of the road (Goldenbeld & van Schagen, 2007). Yet, a challenge has been that not all drivers’ prefer the same speeds, and individual differences with regards to speed preference lead to speed variability and speed conflicts in traffic (Elvik, 2010). The aim of this thesis was to explore whether the speed drivers like to drive when motivated by different driving goals (speed preference) correspond to the speeds that they actually drive on those same roads (speed choice). Additionally, this thesis sought to explore the relationship between speed preference and risk perception. Data was collected in two ways, from a speed gun and from a questionnaire. The speed gun collected on-road measures of driving speeds on seven different roads, while the questionnaire collected measures of drivers’ self-reported speed, speed preference and risk perception. For the speed preference measures, participants were asked what speed they would choose on a given road when: 1) motivated by safety, 2) considering fuel savings, or 3) motivated by fun, and additionally 4) what speed they usually drove on the road. In total 200 drivers were interviewed at five different parking lots, and they referred to the seven roads that were sampled with the speed gun. The results indicated that speed preference helped to explain actual driving speeds. More specifically, drivers’ different driving goals and their large individual differences with regards to speed preference corresponded to different speed choices. No relationship was found, however, between drivers’ speed preferences and their risk perceptions. The results are discussed with regards to implications for the problem of speed variability in traffic
The hyperactive state : ADHD in its historical context
No full textDescribes the historical context of attention deficit hyperactivity disorder (ADHD)
Bounds on the speed and on regeneration times for certain processes on regular trees
No full textWe develop a technique that provides a lower bound on the speed of transient random walk in a random environment on regular trees. A refinement of this technique yields upper bounds on the first regeneration level and regeneration time. In particular, a lower and upper bound on the covariance in the annealed invariance principle follows. We emphasize the fact that our methods are general and also apply in the case of once-reinforced random walk. Durrett, Kesten and Limic [11] prove an upper bound of the form b/(b + d) for the speed on the b-ary tree, where d is the reinforcement parameter. For d > 1 we provide a lower bound of the form g^2b/(b + d), where g is the survival probability of an associated branching process.Random walk in a random environment; once edge-reinforced random walk; lower bound on the speed; regeneration times; regular trees.
Structural and synthetic studies in chemical entomology
No full textThe alarm pheromones of the Ponerine ant Odontomachus troglodytes were found to be an homologous series of 2,6-dimethyi-a-n-aiicyiprazinesz the syntheses of these and 2,5-dimethyl-3-n-alkylprazines and 2,3-dimethyl-5-n-alkylpyrazines are described. The natural products were identified by solid sample gas chromatography, of whole ant heads, linked with mass spectrometry. Their structures were confirmed by spectral and chromatographic comparisons with synthetic samples. The major components were found to be 2,6-dimethyl3-n-butylpyrazine and n-pentylpyrazine with ethylpyrazine and n-hexylpyrazine present as minor components. Caste specific behavioural differences were found between males and workers in response to gland equivalent quantites of the synthetic pheromones. The passive males retreated from the alkylprazines, whereas the workers were attracted to and attacked the pheromone source. The multicomponent sex pheromone system of the Pine Beauty Moth, Panolis flammea, was identified. A variety of techniques including aeration,-so-Wd she gas chromatography and combined gas chromatography-mass spectrometry of solvent extracts of female abdomen tips were used in this study. The components were identified as three mono-unsaturated alkenyl acetates; 9-tetradecenyl acetate, 11-hexadecenyl acetate and 11-tetradecenyl acetate present in the female solvent extract in an approximate ratio of 100:20:1. Unambiguous identification of the natural products was obtained by the technique of methoxymercuration-demercuration with subsequent analysis of the methoxylated derivatives by gas chromatography-mass spectrometry. An initial study of the biological activity of synthetic samples of the (Z)isomers of the proposed natural products showed activity in the field. The Oak Leaf Roller Moth, Tortrix viridana, was also studied mainly by the technique of solid sample gas chromatography and the use of abstractor post loops. Sex specific components could not, however, be identified. The synthesis of three alkenyl acetates, (Z)-ll-tridecenyl acetate, (E)11-tridecenyl acetate and (Z,E)-9,12-tetradecadienyl acetate are described. An approach to the synthesis of the sex pheromone mimic of the American cockroach, Periplaneta americana, germacrene-D is presented. The proposed synthesis involves the formation of the ten-membered ring via a Grob type fragmentation. The synthesis of the fragmentation precursor and preliminary investigations of fragmentation reactions are described. The analysis of a sample of germacrene-D from the cortex oil of Dendroporattrifidus with the spectral data is presented.</p
The kingdome of China [cartographic material] /
No full textMap of China including Japan as well as the Ile Corea [i.e. the "island" of Korea]. Eastern India is displayed on the left of the map. The map displays many decorative features mainly vignettes at the top showing land-yachts for travelling by land, execution by crucifixation, pictorial bird's-eye views of the cities of Macao and Quinzay [i.e. Hangchow], and on the sides eight costumes from men and women of Asian cultures. Relief is shown pictorially.; Title in cartouche.; Decorative border of painted scenes at top of map: Ye. Ma[n]ner of their Trauelling by la[n]d' -- 'Macao' -- [Blank shield without coat of arms] -- Quinzay -- the Manner of their Execution.; Decorative border of painted scenes at left of map: A Chinian woman -- A souldier of Iapan -- A Chinian -- A men of Pegu.; Decorative border of painted scenes at right of map: A Chinian men -- A Chinian men -- A Souldier of Iapon -- A women of Pegu.; Imprint on map: [London] : Are to be sold by Tho. Bassett in Fleet Street and Ric. Chiswell in St. Pauls Church Yard, 1626.; Text on verso entitled: The description of the Kingdom of China, p. 38-39 (includes signature: T).; Map 19 from: A prospect of the most famous parts of the world, viz, Asia, Africa, Europe, America with these empires and kingdoms ... / by John Speed. London : Printed for Thomas Bassett at the George in Fleet Street and Richard Chiswell at the Rose and Crown in St. Pauls Church Yard, 1676.; Shirley, R. Maps in the atlases of the British Library ; T-SPE-2f; Also available in an electronic version via the Internet at: http://nla.gov.au/nla.map-rm272.Kingdom of ChinaVerso text title Description of the Kingdom of Chin
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