856 resultados para geometry features
Resumo:
Integrated in a wide research assessing destabilizing and triggering factors to model cliff dynamic along the Dieppe's shoreline in High Normandy, this study aims at testing boat-based mobile LiDAR capabilities by scanning 3D point clouds of the unstable coastal cliffs. Two acquisition campaigns were performed in September 2012 and September 2013, scanning (1) a 30-km-long shoreline and (2) the same test cliffs in different environmental conditions and device settings. The potentials of collected data for 3D modelling, change detection and landslide monitoring were afterward assessed. By scanning during favourable meteorological and marine conditions and close to the coast, mobile LiDAR devices are able to quickly scan a long shoreline with median point spacing up to 10cm. The acquired data are then sufficiently detailed to map geomorphological features smaller than 0.5m2. Furthermore, our capability to detect rockfalls and erosion deposits (>m3) is confirmed, since using the classical approach of computing differences between sequential acquisitions reveals many cliff collapses between Pourville and Quiberville and only sparse changes between Dieppe and Belleville-sur-Mer. These different change rates result from different rockfall susceptibilities. Finally, we also confirmed the capability of the boat-based mobile LiDAR technique to monitor single large changes, characterizing the Dieppe landslide geometry with two main active scarps, retrogression up to 40m and about 100,000m3 of eroded materials.
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Aim of the study: Mycorrhizal fungi in Mediterranean forests play a key role in the complex process of recovery after wildfires. A broader understanding of an important pyrophytic species as Pinus pinaster and its fungal symbionts is thus necessary for forest restoration purposes. This study aims to assess the effects of ectomycorrhizal symbiosis on maritime pine seedlings and how fire severity affects fungal colonization ability. Area of study: Central Spain, in a Mediterranean region typically affected by wildfires dominated by Pinus pinaster, a species adapted to fire disturbance. Material and Methods: We studied P. pinaster root apexes from seedlings grown in soils collected one year after fire in undisturbed sites, sites moderately affected by fire and sites highly affected by fire. Natural ectomycorrhization was observed at the whole root system level as well as at two root vertical sections (0-10 cm and 10-20 cm). We also measured several morphometric traits ( tap root length, shoot length, dry biomass of shoots and root/shoot ratio), which were used to test the influence of fire severity and soil chemistry upon them. Main results: Ectomycorrhizal colonization in undisturbed soils for total and separated root vertical sections was higher than in soils that had been affected by fire to some degree. Inversely, seedling vegetative size increased according to fire severity. Research highlights: Fire severity affected soil properties and mycorrhizal colonization one year after occurrence, thus affecting plant development. These findings can contribute to a better knowledge of the factors mediating successful establishment of P. pinaster in Mediterranean forests after wildfires.
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In this paper the authors propose a new closed contour descriptor that could be seen as a Feature Extractor of closed contours based on the Discrete Hartley Transform (DHT), its main characteristic is that uses only half of the coefficients required by Elliptical Fourier Descriptors (EFD) to obtain a contour approximation with similar error measure. The proposed closed contour descriptor provides an excellent capability of information compression useful for a great number of AI applications. Moreover it can provide scale, position and rotation invariance, and last but not least it has the advantage that both the parameterization and the reconstructed shape from the compressed set can be computed very efficiently by the fast Discrete Hartley Transform (DHT) algorithm. This Feature Extractor could be useful when the application claims for reversible features and when the user needs and easy measure of the quality for a given level of compression, scalable from low to very high quality.
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Objectives: To describe the clinical features of patients diagnosed with oral lichen planus (OLP) and to establish the prevalence of its malignant transformation in our setting. Study design: A retrospective study was made of 65 patients clinically and histologically diagnosed with OLP in the Service of Oral Surgery (Dental Clinic of the University of Barcelona, Spain) in the period 1990-2005. A descriptive and bivariate statistical analysis was made. Results: The mean patient age was 59 years (SD ± 14.9). Most of the patients (61%) were women, and the most frequent location of the lesions was the buccal mucosa (90.8%). White forms of OLP were noted in 66% of the cases, and 46.2% of the patients reported symptoms of some kind. The patients diagnosed with diabetes mellitus (20%) showed a larger proportion of red lesions (p=0.088). No statistically significant association was observed between chronic liver disease and the OLP lesion types or symptoms. Two cases of squamous cell carcinoma were identified in two patients previously or simultaneously diagnosed with OLP. A statistically significant correlation was observed between dysplastic changes / malignization of the lesions and smoking habit (p=0.019). An association to alcohol abuse was also noted, though in this case statistical significance was not reached (p=0.085). Conclusions: The clinical features of our study population were similar to those described in other studies. Diabetic patients with OLP were seen to be more susceptible to the development of atrophic-erosive lesions. Smokers and/or patients with alcohol abuse in turn showed a greater tendency to develop dysplastic changes / malignization in the histopathological study of the lesions
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Objectives: The purpose of this study was to determine the incidence and clinical symptoms associated with sharp mandibular bone irregularities (SMBI) after lower third molar extraction and to identify possible risk factors for this complication. Study Design: A mixed study design was used. A retrospective cohort study of 1432 lower third molar extractions was done to determine the incidence of SMBI and a retrospective case-control study was done to determine potential demographic and etiologic factors by comparing those patients with postoperative SMBI with controls. Results: Twelve SMBI were found (0.84%). Age was the most important risk factor for this complication. The operated side and the presence of an associated radiolucent image were also significantly related to the development of mandibular bone irregularities. The depth of impaction of the tooth might also be an important factor since erupted or nearly erupted third molars were more frequent in the SMBI group. Conclusions: SMBI are a rare postoperative complication after lower third molar removal. Older patients having left side lower third molars removed are more likely to develop this problem. The treatment should be the removal of the irregularity when the patient is symptomatic
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Pro-gradu –tutkielmani aiheena ovat 1700-luvun ”karanneet orjat” – sanomalehtiilmoitusten genrelle ominaiset piirteet. Tutkimusaineisto koostuu 190 ilmoituksesta, jotka ovat alkuperäisesti ilmestyneet virginialaisissa, pennsylvanialaisissa ja newyorkilaisissa sanomalehdissä 1730-luvulta 1770-luvulle. Tutkimuksen kohteeksi on rajattu ilmoitukset, joissa yksityishenkilöt ilmoittavat orjan/orjien karanneet ja lupaavat kiinniottajalle palkkion. Tutkielman tarkoituksena on tarkastella, millaisia ovat tyypilliset kielelliset piirteet näissä teksteissä ja millainen on prototyyppinen genren edustaja. Genreteorian lisäksi teoriaosuudessa käsittelen jonkin verran 1700- luvun englannin kielen yleisiä piirteitä sekä orjuuden ja sanomalehtien syntyhistoriaa Amerikassa taustoittaakseni tutkimusta. Analyysissa hyödynnän mm. Swalesin ja Bhatian käyttämää käsitettä siirroista (moves). Tutkin ilmoituksien tyypillistä rakennetta jakamalla ne yhdeksään siirtoon, joilla kaikilla on oma tehtävänsä ilmoituksessa. Jotkut siirrot, kuten karkulaisen kuvailu ja palkkion lupaaminen, esiintyvät kaikissa ilmoituksissa, kun taas toiset siirrot ovat läsnä harvemmin. Muita tälle genrelle tyypillisiä ominaisuuksia ovat esim. ilmoituksissa toistuvat kiinteät fraasit ja tietyt sanastolliset erikoisuudet. Lisäksi tutkin ilmoituksissa käytettäviä tapoja viitata asiaan liittyviin henkilöihin, sekä erilaisia toimia, joita ilmoitusten jättäjät ilmoituksien avulla suorittavat. Genressä on havaittavissa pieniä reilun neljänkymmenen vuoden kuluessa tapahtuneita muutoksia, mutta myös eroavaisuuksia eri siirtokuntien ilmoitusten välillä. Yleisesti voidaan todeta, että vaikka ”karanneet orjat” –ilmoitukset voivat vaihdella rakenteeltaan ja sanavalinnoiltaan, suuri osa ilmoituksista seuraa kuitenkin melko prototyyppistä muottia.
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Centrifugal compressors are widely used for example in refrigeration processes, the oil and gas industry, superchargers, and waste water treatment. In this work, five different vaneless diffusers and six different vaned diffusers are investigated numerically. The vaneless diffusers vary only by their diffuser width, so that four of the geometries have pinch implemented to them. Pinch means a decrease in the diffuser width. Four of the vaned diffusers have the same vane turning angle and a different number of vanes, and two have different vane turning angles. The flow solver used to solve the flow fields is Finflo, which is a Navier-Stokes solver. All the cases are modeled with the Chien's k – έ- turbulence model, and selected cases are modeled also with the k – ώ-SST turbulence model. All five vaneless diffusers and three vaned diffusers are investigated also experimentally. For each construction, the compressor operating map is measured according to relevant standards. In addition to this, the flow fields before and after the diffuser are measured with static and total pressure, flow angle and total temperature measurements. When comparing the computational results to the measured results, it is evident that the k – ώ-SST turbulence model predicts the flow fields better. The simulation results indicate that it is possible to improve the efficiency with the pinch, and according to the numerical results, the two best geometries are the ones with most pinch at the shroud. These geometries have approximately 4 percentage points higher efficiency than the unpinched vaneless diffusers. The hub pinch does not seem to have any major benefits. In general, the pinches make the flow fields before and after the diffuser more uniform. The pinch also seems to improve the impeller efficiency. This is down to two reasons. The major reason is that the pinch decreases the size of slow flow and possible backflow region located near the shroud after the impeller. Secondly, the pinches decrease the flow velocity in the tip clearance, leading to a smaller tip leakage flow and therefore slightly better impeller efficiency. Also some of the vaned diffusers improve the efficiency, the increment being 1...3 percentage points, when compared to the vaneless unpinched geometry. The measurement results confirm that the pinch is beneficial to the performance of the compressor. The flow fields are more uniform with the pinched cases, and the slow flow regions are smaller. The peak efficiency is approximately 2 percentage points and the design point efficiency approximately 4 percentage points higher with the pinched geometries than with the un- pinched geometry. According to the measurements, the two best geometries are the ones with the most pinch at the shroud, the case with the pinch only at the shroud being slightly better of the two. The vaned diffusers also have better efficiency than the vaneless unpinched geometries. However, the pinched cases have even better efficiencies. The vaned diffusers narrow the operating range considerably, whilst the pinch has no significant effect on the operating range.
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The promotion of energy-efficient appliances is necessary to reduce the energetic and environmental burden of the household sector. However, many studies have reported that a typical consumer underestimates the benefits of energy-saving investment on the purchase of household electric appliances. To analyze this energy-efficiency gap problem, many scholars have estimated implicit discount rates that consumers use for energy-consuming durables. Although both hedonic and choice models have been used in previous studies, a comparison between two models has not yet been done. This study uses point of sale data about Japanese residential air conditioners and estimates implicit discounts rates with both hedonic and choice models. Both models demonstrate that a typical consumer underinvests in energy efficiency. Although choice models estimate a lower implicit discount rate than hedonic models, the latter models estimate the values of other product characteristics more consistently than choice models.
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This Master's thesis studies the development of interaction and socialization in online communities. A large number of online communities fade away even before they really get started. In many occasions the reason is that the community does not give anything new, or even if they do, the delivery does not satisfy the users. In this thesis guidelines were developed to help to see important things, which might be forgotten when developing an online community. The thesis goes through the characteristic of an online community and human behaviour related to them and also compares behaviour in the Internet and real life. In addition, usability is an important part of the online communities and thus it is also covered in this thesis. As a result of this thesis an 8-step guideline was developed to ease the design of an online community. Guidelines were also applied to two real life cases which are described as one part of this work.
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Determination of virus diversity in the field is vital to support a sustainable breeding program for virus resistance of horticultural crops. The present study aimed to characterize four field potyvirus isolates found naturally infecting sweet pepper (Capsicum annuum) (Sa66 and Sa115) and tomato (Lycopersicon esculentum) (IAC3 and Sa21) plants. Their biological characteristics revealed differences among the isolates in their ability to infect distinct Capsicum spp. and tomato genotypes, and in the severity of symptoms caused by these isolates compared to the infection caused by an isolate of Pepper yellow mosaic virus (PepYMV). Absence of cross-reaction was found among the studied isolates with antiserum against Potato virus Y (PVY). However, all isolates reacted, at different intensities, with antiserum against PepYMV. All isolates showed high identity percentage (97 to 99%) of the amino acid sequence of the coat protein with PepYMV (accession AF348610) and low (69 to 80%) with other potyvirus species. The comparison of the 3' untranslated region also confirmed this finding with 97 to 98% identity with PepYMV, and of 47 to 71% with other potyviruses. The results showed that PepYMV isolates were easily differentiated from PVY by serology and that the host response of each isolate could be variable. In addition, the nucleotide sequence of the coat protein and 3' untranslated region was highly conserved among the isolates.
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This work quantifies two important epidemiological features of the bean (Phaseolus vulgaris)/Phaeoisariopsis griseola pathosystem. The first is the effect of the number of nights of leaf wetness on infection efficiency. Infection efficiency was below 10% when inoculated leaflets were exposed to less than two nights of leaf wetness. Optimum infection efficiencies were obtained after three to four nights of leaf wetness, at about 50%. Further nights of leaf wetness did not increase the infection efficiency. The second feature quantified is the relative rate of leaflet defoliation for varying levels of angular leaf spot severity. It increased with disease severity according to a logarithm-like curve, and a relative rate of 0.23 day-1 was estimated for a severity of 18%. The implications of these results on the disease epidemiology are discussed.
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Valupurseiden ja jäysteiden poistaminen on osa alumiinipainevalujen tuotantoprosessia. Työssä on tutkittu käytössä olevien ja uusien menetelmien mahdollisuuksia taloudellisempaan tuotantoon. Purseiden ja jäysteiden poistamiseen käytettävien menetelmien lisäksi tutkimuskohteita ja ideoita on haettu muista metallien työstömenetelmistä. Valupurseiden ja jäysteiden määritelmiä, muodostumista ja luokittelua on esitelty laajasti. Menetelmien tutkimus on painottunut valupurseiden poistamiseen ja valun jälkeistä leikkaamista on tutkittu erityisesti sisäpuolisten muotojen työstämiseen käytettyjen pistintyökalujen kautta. Muotin ulostyöntötapin purseen poistaminen on ollut tärkeä asia menetelmien tutkimuksissa. Valupurseiden, leikkaus- ja koneistusjäysteiden poistamiseksi lastuavista työstömenetelmistä tutkittuja ovat koneistaminen koneistuskeskuksella, aventaminen, hiertopuhallus, suihkuhiertäminen, vesisuihkuleikkaus, ultraäänityöstö, harjaus, painehiertäminen, hiominen kohdistetuilla ja kohdistamattomilla menetelmillä. Myös terminen jäysteenpoistomenetelmä (TEM), kemiallinen työstö (ECM) ja laserleikkaus on otettu esiin tutkimuksessa. Työn tuloksena on näkemys tutkittujen menetelmien jatkokehitystarpeesta ja mahdollisuudesta soveltaa niitä sarjatuotantoon.
Resumo:
Blood flow in human aorta is an unsteady and complex phenomenon. The complex patterns are related to the geometrical features like curvature, bends, and branching and pulsatile nature of flow from left ventricle of heart. The aim of this work was to understand the effect of aorta geometry on the flow dynamics. To achieve this, 3D realistic and idealized models of descending aorta were reconstructed from Computed Tomography (CT) images of a female patient. The geometries were reconstructed using medical image processing code. The blood flow in aorta was assumed to be laminar and incompressible and the blood was assumed to be Newtonian fluid. A time dependent pulsatile and parabolic boundary condition was deployed at inlet. Steady and unsteady blood flow simulations were performed in real and idealized geometries of descending aorta using a Finite Volume Method (FVM) code. Analysis of Wall Shear Stress (WSS) distribution, pressure distribution, and axial velocity profiles were carried out in both geometries at steady and unsteady state conditions. The results obtained in thesis work reveal that the idealization of geometry underestimates the values of WSS especially near the region with sudden change of diameter. However, the resultant pressure and velocity in idealized geometry are close to those in real geometry
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This work describes a method to determine Cu at wide range concentrations in a single run without need of further dilutions employing high-resolution continuum source flame atomic absorption spectrometry. Different atomic lines for Cu at 324.754 nm, 327.396 nm, 222.570 nm, 249.215 nm and 224.426 nm were evaluated and main figures of merit established. Absorbance measurements at 324.754 nm, 249.215 nm and 224.426 nm allows the determination of Cu in the 0.07 - 5.0 mg L-1, 5.0 - 100 mg L-1 and 100 - 800 mg L-1 concentration intervals respectively with linear correlation coefficients better than 0.998. Limits of detection were 21 µg L-1, 310 µg L-1 and 1400 µg L-1 for 324.754 nm, 249.215 nm and 224.426 nm, respectively and relative standard deviations (n = 12) were £ 2.7%. The proposed method was applied to water samples spiked with Cu and the results were in agreement at a 95% of confidence level (paired t-test) with those obtained by line-source flame atomic absorption spectrometry.