4,438 research outputs found

    The knowledge that shapes the city:the human city beneath the social city

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    In the Atlanta Symposium (Hillier, 2001, 2003a) a theory of the social constructionof the city was presented. In this paper it is proposed that underlying the variouskinds of social city there is a deeper, more generic human city, which arises from thepervasive intervention of the human cognitive subject in the shaping and workingof the city. This intervention is explored at two critical stages in the forming of thecity: in the 'vertical' form-creating process by which the accumulation of built formscreates an emergent spatial pattern; and in the 'lateral' form-function process bywhich the emergent spatial pattern shapes movement and sets off the process bywhich an aggregate of buildings becomes a living city. The nature of these cognitiveinterventions is investigated by asking a question: how do human beings 'synchronise'diachronically acquired (and diachronically created) spatial information into asynchronic picture of ambient urban spatial patterns, since it is such synchronicpictures which seem to mediate both interventions? A possible answer is sought bydeveloping the concept of 'description retrieval', originally proposed in 'The SocialLogic of Space' as the means by which human beings retrieve abstract informationfrom patterns of relations in the real world. Our ability to retrieve such descriptionhappens, it is argued, at more than one level, and can includes the high-level notionsof the grid which seems to plays a key role in cognitive intervention in the city.Finally we ask what the ubiquity of the human cognitive subject in the formation ofthe city implies for how we should see cities as complex systems. It is argued that,as with language, there is a 'objective subject' at the heart of the processes by whichcities come into existence, and that this provides us both with the need and themeans to mediate between the social physics paradigm of the city, with its focus onthe mathematics of the generation of the physical city and phenomenologicalparadigm with its - too often anti-mathematical - focus on the human experience ofthe city. Since the intervention of the cognitive subject involves formal ideas andhas formal consequences for the structure of the city, we cannot, it is argued, explaineither without the other

    Vision technology/algorithms for space robotics applications

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    The thrust of automation and robotics for space applications has been proposed for increased productivity, improved reliability, increased flexibility, higher safety, and for the performance of automating time-consuming tasks, increasing productivity/performance of crew-accomplished tasks, and performing tasks beyond the capability of the crew. This paper provides a review of efforts currently in progress in the area of robotic vision. Both systems and algorithms are discussed. The evolution of future vision/sensing is projected to include the fusion of multisensors ranging from microwave to optical with multimode capability to include position, attitude, recognition, and motion parameters. The key feature of the overall system design will be small size and weight, fast signal processing, robust algorithms, and accurate parameter determination. These aspects of vision/sensing are also discussed

    Improving the altimetric rain record from Jason-1 & Jason-2

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    Dual-frequency rain-flagging has long been a standard part of altimetric data analysis, both for quality control of the data and for the study of rain itself, because altimeters can provide a finer spatial sampling of rain than can passive microwave instruments. However, there have been many varied implementations, using different records of the surface backscatter and different thresholds. This paper compares four different measures available for the recently-launched Jason-2. The evaluation compares these measures against clearly desired properties, finding that in most cases the adjusted backscatter and that from the ice retracker perform much better than that recommended in the users' handbook. The adjusted backscatter measure also provides a much better link to observations from Jason-1, opening up a much longer period for consistent rain investigations, and enabling greatly improved analysis of the short-scale variability of precipitation. Initial analysis shows that although the spatial and temporal gradients of backscatter increase at very low winds, the spatial gradients in rain attenuation are concentrated where rainfall is greatest, whilst the temporal changes have a simple broad latitudinal pattern

    Combining perceptual features with diffusion distance for face recognition

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    Analysis on Using Synthesized Singing Techniques in Assistive Interfaces for Visually Impaired to Study Music

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    Tactile and auditory senses are the basic types of methods that visually impaired people sense the world. Their interaction with assistive technologies also focuses mainly on tactile and auditory interfaces. This research paper discuss about the validity of using most appropriate singing synthesizing techniques as a mediator in assistive technologies specifically built to address their music learning needs engaged with music scores and lyrics. Music scores with notations and lyrics are considered as the main mediators in musical communication channel which lies between a composer and a performer. Visually impaired music lovers have less opportunity to access this main mediator since most of them are in visual format. If we consider a music score, the vocal performer’s melody is married to all the pleasant sound producible in the form of singing. Singing best fits for a format in temporal domain compared to a tactile format in spatial domain. Therefore, conversion of existing visual format to a singing output will be the most appropriate nonlossy transition as proved by the initial research on adaptive music score trainer for visually impaired [1]. In order to extend the paths of this initial research, this study seek on existing singing synthesizing techniques and researches on auditory interfaces

    Titan's atmosphere as observed by Cassini/VIMS solar occultations: CH4_4, CO and evidence for C2_2H6_6 absorption

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    We present an analysis of the VIMS solar occultations dataset, which allows us to extract vertically resolved information on the characteristics of Titan's atmosphere between 100-700 km with a characteristic vertical resolution of 10 km. After a series of data treatment procedures, 4 occultations out of 10 are retained. This sample covers different seasons and latitudes of Titan. The transmittances show clearly the evolution of the haze and detect the detached layer at 310 km in Sept. 2011 at mid-northern latitudes. Through the inversion of the transmission spectra with a line-by-line radiative transfer code we retrieve the vertical distribution of CH4_4 and CO mixing ratio. The two methane bands at 1.4 and 1.7 {\mu}m are always in good agreement and yield an average stratospheric abundance of 1.28±0.081.28\pm0.08%. This is significantly less than the value of 1.48% obtained by the GCMS/Huygens instrument. The analysis of the residual spectra after the inversion shows that there are additional absorptions which affect a great part of the VIMS wavelength range. We attribute many of these additional bands to gaseous ethane, whose near-infrared spectrum is not well modeled yet. Ethane contributes significantly to the strong absorption between 3.2-3.5 {\mu}m that was previously attributed only to C-H stretching bands from aerosols. Ethane bands may affect the surface windows too, especially at 2.7 {\mu}m. Other residual bands are generated by stretching modes of C-H, C-C and C-N bonds. In addition to the C-H stretch from aliphatic hydrocarbons at 3.4 {\mu}m, we detect a strong and narrow absorption at 3.28 {\mu}m which we tentatively attribute to the presence of PAHs in the stratosphere. C-C and C-N stretching bands are possibly present between 4.3-4.5 {\mu}m. Finally, we obtain the CO mixing ratio between 70-170 km. The average result of 46±1646\pm16 ppm is in good agreement with previous studies.Comment: 51 pages, 28 figure

    In-situ health monitoring for wind turbine blade using acoustic wireless sensor networks at low sampling rates

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    PhD ThesisThe development of in-situ structural health monitoring (SHM) techniques represents a challenge for offshore wind turbines (OWTs) in order to reduce the cost of the operation and maintenance (O&M) of safety-critical components and systems. This thesis propos- es an in-situ wireless SHM system based on acoustic emission (AE) techniques. The proposed wireless system of AE sensor networks is not without its own challenges amongst which are requirements of high sampling rates, limitations in the communication bandwidth, memory space, and power resources. This work is part of the HEMOW- FP7 Project, ‘The Health Monitoring of Offshore Wind Farms’. The present study investigates solutions relevant to the abovementioned challenges. Two related topics have been considered: to implement a novel in-situ wireless SHM technique for wind turbine blades (WTBs); and to develop an appropriate signal pro- cessing algorithm to detect, localise, and classify different AE events. The major contri- butions of this study can be summarised as follows: 1) investigating the possibility of employing low sampling rates lower than the Nyquist rate in the data acquisition opera- tion and content-based feature (envelope and time-frequency data analysis) for data analysis; 2) proposing techniques to overcome drawbacks associated with lowering sampling rates, such as information loss and low spatial resolution; 3) showing that the time-frequency domain is an effective domain for analysing the aliased signals, and an envelope-based wavelet transform cross-correlation algorithm, developed in the course of this study, can enhance the estimation accuracy of wireless acoustic source localisa- tion; 4) investigating the implementation of a novel in-situ wireless SHM technique with field deployment on the WTB structure, and developing a constraint model and approaches for localisation of AE sources and environmental monitoring respectively. Finally, the system has been experimentally evaluated with the consideration of the lo- calisation and classification of different AE events as well as changes of environmental conditions. The study concludes that the in-situ wireless SHM platform developed in the course of this research represents a promising technique for reliable SHM for OWTBs in which solutions for major challenges, e.g., employing low sampling rates lower than the Nyquist rate in the acquisition operation and resource constraints of WSNs in terms of communication bandwidth and memory space are presente

    Preliminary system design of a Three Arm Capture Mechanism (TACM) flight demonstration article

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    The overall objective of the Three Arm Capture Mechanism (TACM) is to serve as a demonstration of capability for capture of objects in space. These objects could be satellites, expended boosters, pieces of debris, etc.; anything of significant size. With this capability we can significantly diminish the danger of major collisions of debris with valuable space assets and with each other, which would otherwise produce many smaller, high velocity pieces of debris which also become concerns. The captured objects would be jettisoned into the atmosphere, relocated in 'parking' orbits, or recovered for disposition or refurbishment. The dollar value of satellites launched into space continues to grow along with the cost of insurance; having a capture capability takes a positive step towards diminishing this added cost. The effort covered is a planning step towards a flight demonstration of the satellite capture capability. Based on the requirement to capture a communication class satellite, its associated booster, or both, a preliminary system definition of a retrieval kit is defined. The objective of the flight demonstration is to demonstrate the techniques proposed to perform the mission and to obtain data on technical issues requiring an in situ space environment. The former especially includes issues such as automated image recognition techniques and control strategies that enable an unmanned vehicle to rendezvous and capture a satellite, contact dynamics between the two bodies, and the flight segment level of automation required to support the mission. A development plan for the operational retrieval capability includes analysis work, computer and ground test simulations, and finally a flight demonstration. A concept to perform a selected mission capturing a precessing communications satellite is described. Further development efforts using analytical tools and laboratory facilities are required prior to reaching the point at which a full commitment to the flight demonstration design can be made

    Atypical MEG inter-subject correlation during listening to continuous natural speech in dyslexia

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    Listening to speech elicits brain activity time-locked to the speech sounds. This so-called neural entrainment to speech was found to be atypical in dyslexia, a reading impairment associated with neural speech processing deficits. We hypothesized that the brain responses of dyslexic vs. normal readers to real-life speech would be different, and thus the strength of inter-subject correlation (ISC) would differ from that of typical readers and be reflected in reading-related measures. We recorded magnetoencephalograms (MEG) of 23 dyslexic and 21 typically-reading adults during listening to ∼10 min of natural Finnish speech consisting of excerpts from radio news, a podcast, a self-recorded audiobook chapter and small talk. The amplitude envelopes of band-pass-filtered MEG source signals were correlated between subjects in a cortically-constrained source space in six frequency bands. The resulting ISCs of dyslexic and typical readers were compared with a permutation-based t-test. Neuropsychological measures of phonological processing, technical reading, and working memory were correlated with the ISCs utilizing the Mantel test. During listening to speech, ISCs were mainly reduced in dyslexic compared to typical readers in delta (0.5–4 Hz) and high gamma (55–90 Hz) frequency bands. In the theta (4−8 Hz), beta (12–25 Hz), and low gamma (25−45 Hz) bands, dyslexics had enhanced ISC to speech compared to controls. Furthermore, we found that ISCs across both groups were associated with phonological processing, technical reading, and working memory. The atypical ISC to natural speech in dyslexics supports the temporal sampling deficit theory of dyslexia. It also suggests over-synchronization to phoneme-rate information in speech, which could indicate more effort-demanding sampling of phonemes from speech in dyslexia. These irregularities in parsing speech are likely some of the complex neural factors contributing to dyslexia. The associations between neural coupling and reading-related skills further support this notion.Peer reviewe
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