131,189 research outputs found
Video vehicle detection at signalised junctions: a simulation-based study
No full textMany existing advanced methods of traffic signal control depend on information about
approaching traffic provided by inductive loop detectors at particular points in the road. But
analysis of images from CCTV cameras can in principle provide more comprehensive
information about traffic approaching and passing through junctions, and cameras may be
easier to install and maintain than loop detectors, and some systems based on video detection
have already been in use for some time.
Against this background, computer simulation has been used to explore the potential of
existing and immediately foreseeable capability in automatic on-line image analysis to extract
information relevant to signal control from images provided by cameras mounted in
acceptable positions at signal-controlled junctions. Some consequences of extracting relevant
information in different ways were investigated in the context of an existing detailed
simulation model of vehicular traffic moving through junctions under traffic-responsive signal
control, and the development of one basic and one advanced algorithm for traffic-responsive
control. The work was confined as a first step to operation of one very simple signalcontrolled
junction.
Two techniques for extraction of information from images were modelled - a more ambitious
technique based on distinguishing most of the individual vehicles visible to the camera, and a
more modest technique requiring only that the presence of vehicles in any part of the image
be distinguished from the background scene. In the latter case, statistical modelling was used
to estimate the number of vehicles corresponding to any single area of the image that
represents vehicles rather than background.
At the simple modelled junction, each technique of extraction enabled each of the algorithms
for traffic-responsive control of the signals to achieve average delays per vehicle appreciably
lower than those given by System D control, and possibly competitive with those that MOVA
would give, but comparison with MOVA was beyond the scope of the initial study.
These results of simulation indicate that image analysis of CCTV pictures should be able to
provide sufficient information in practice for traffic-responsive control that is competitive
with existing techniques. Ways in which the work could be taken further were discussed with
practitioners, but have not yet been progressed
Modeling the evolution of natural cliffs subject to weathering. 2, Discrete element approach
No full textThe evolution of slopes subjected to weathering has been modeled by assuming Mohr-Coulomb behavior and by using a numerical approach based on the discrete element method (DEM). According to this method, soil and/or rock are represented by an assembly of bonded particles. Particle bonds are subject to progressive weakening, and so the material weathering and removal processes are modeled. Slope instability and material movement follow the decrease of material strength in space and time with the only assumption concerning the weathering distribution within the slope. First, the case of cliffs subject to strong erosion (weathering-limited conditions) and uniform weathering was studied to compare the results of the DEM approach with the limit analysis approach. Second, transport-limited slopes subject to nonuniform slope weathering were studied. Results have been compared with experimental data and other geomorphologic models from the literature (Fisher-Lehmann and Bakker–Le Heux). The flux of material from the slope is modeled assuming degradation both in space and time
Gli spazi pubblici nel post-disastro: questioni di standard
No full textIl modello sociale all’inizio del XX° secolo, in parte legato ad un approccio sociologico strutturalistico e funzionalistico non è più rispondente alle condizioni contemporanee. Pertanto, i suoi prodotti, come l’idea stessa degli standard urbanistici quantitativi, sempre misurabili, e la stessa zonizzazione, entrano in crisi e il loro paradigma necessita di nuovi modelli che non necessariamente sono legati alle forme tradizionali di spazio pubblico, che richiede principi di flessibilità e dinamismo (modifica nel tempo) necessari anche nelle nuove forme di pianificazione. Il ruolo degli spazi pubblici in tale contesto è centrale, e la loro analisi, in relazione ai fattori di forma, funzione, tipo, percezione, tecnologia, architettura, tempo e modelli sociali di riferimento, consente di individuarne le nuove dimensioni, quelle contemporanee, in cui il concetto stesso di forma assume un nuovo significato: il superamento del carattere geometrico-misurabile in favore di quello relazionale/temporale.
L’osservazione degli spazi pubblici in contesti urbani e sociali post disastro, fa emergere elementi sostanziali di cui le politiche di piano devono tener conto nella riorganizzazione e nella gestione ulteriore del territorio coinvolto. Durante un periodo post disastro, si rilevano alcuni fenomeni ricorrenti: spostamento demografico; abbandono e progressivo oblio degli spazi pubblici negati; trasformazione delle esigenze e dei modelli sociali locali; emergenza di nuove priorità sociali. Dall’analisi dei casi studio e dalla sintesi dei dati raccolti viene delineata una prospettiva qualitativa che integra il valore degli standard proprio nei contesti urbani, a partire dal ruolo strutturale ricoperto dagli spazi pubblici nell’armatura urbana
Pristinamycin-inducible gene regulation in mycobacteria
No full textIn this work the Pip-inducible system, already used in eukaryotes, was tested in mycobacteria. This system is based on the Streptomyces coelicolor Pip repressor, the Streptomyces pristinaespiralis ptr promoter and the inducer pristinamycin I. By cloning in an integrative plasmid the ptr promoter upstream of the lacZ reporter gene and the pip gene under the control of a constitutive mycobacterial promoter, we demonstrated that the ptr promoter activity increased up to 50-fold in Mycobacterium smegmatis and up to 400-fold in Mycobacterium tuberculosis, in dependence on pristinamycin I concentration, and that the promoter was fully repressed in the absence of the inducer.
Three mycobacterial genes were cloned under pptr –Pip control, both in sense and antisense direction; both proteins and antisense RNAs could be overexpressed, the antisenses causing a partial reduction of the amount of the targeted proteins. This system was used to obtain two M. tuberculosis conditional mutants in the fadD32 and pknB genes: the mutant strains grew only in the presence of the inducer pristinamycin I. Thus it showed to be an effective inducible system in mycobacteria
Modeling the evolution of natural cliffs subject to weathering. 1, Limit analysis approach
No full textRetrogressive landsliding evolution of natural slopes subjected to weathering has been modeled by assuming Mohr-Coulomb material behavior and by using an analytical method. The case of weathering-limited slope conditions, with complete erosion of the accumulated debris, has been modeled. The limit analysis upper-bound method is used to study slope instability induced by a homogeneous decrease of material strength in space and time. The only assumption required in the model concerns the degree of weathering within the slope, and for this we assumed and tested different weathering laws. By means of this method, the evolution of cliffs subject to strong weathering conditions (weathering-limited conditions) was predicted. The discrete succession of failures taking place was modeled taking into account the geometry assumed by slopes as a consequence of previous mass movements. The results have been compared with published data from long-term slope monitoring and show a good match between experimental observations and analytical predictions. The retrogressive evolution of the slope occurs with decreasing size of the unstable blocks, following a logarithmic volume-frequency relationship. A nonlinear relationship is found between mass flux and average slope gradient. A set of normalized solutions is presented both by nomograms and tables for different values of slope angle, cohesion, and internal friction angle
Métisser l\u27oralité, l\u27écriture et l\u27art floral : la transartialité chez Joseph Zobel
No full textLa communication de Suzanne CROSTA, professeur titulaire en Littératures francophones au Département de français de l\u27Université McMaster (Hamilton, Canada), propose de contribuer à la réception critique du projet d\u27écriture de Joseph Zobel et de dégager les traits saillants des pratiques transartistiques chez Zobel. La réflexion proposée ici se veut un regard sur l\u27oeuvre de ce grand écrivain en général, sur son récit de vie, d\u27Amour et de Silence, tout en mettant en exergue les fils qui lient l\u27oralité à l\u27écriture et celles-ci à l\u27art floral
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Risultati di un Confronto Teorico-Sperimentale nello Studio delle Caratteristiche Aerodinamiche di una Fusoliera di Elicottero
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Modelli idrologico-idraulici per la previsione operativa delle piene: valutazioni sugli effetti delle scale della modellazione idrologica
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