744 research outputs found

    2D Model of a Floating Body Under Nonlinear Waves

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    A model describing the dynamics of a floating body by solving the NS-equations in a moving grid framework with free surface is presented. The model has several interesting features, like the peculiar way of describing: a) the grid movements; b) the slip boundary conditions in presence of a wet and dry interface; c) the generation of waves and, to some extents, the sponge layers. The investigated feature is the ratio between the oscillation of the floating body and the wave oscillation, which is usually quite overestimated by viscousless models when the load frequency is close to the floating body eigenfrequency. A simulation of this condition with the non-linear model reproduced much more closely the experimental results described in Ruol and Martinelli (Comsol User Conference, 2007) than the corresponding simulation carried out with a classical model based on linear waves and irrotational flow

    Congenital pancreatoblastoma: a case report

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    The literature describes 15 cases of congenital pancreatoblastoma (PB): 5 had prenatal diagnosis, none had metastases at diagnosis, 7 were associated with BeckwitheWiedemann syndrome (BWS). In 13 cases resection was radical, while in 2 there were macroscopic residues. Only one patient underwent chemotherapy after distant recurrence. All children are alive except one who died because of problems related to BWS. Our goal is to describe the approach adopted in an infant with congenital PB treated in our center. After a prenatal third semester diagnosis of abdominal anechoic lesion, the radiological investigations (ultrasound, MRI) performed at birth described a cystic lesion of unclear nature. We proceeded to laparoscopic exploration, transformed into open approach after the detection of a lesion located in the body of the pancreas; this lesion was resected, preserving the head and tail of pancreas. The histological diagnosis showed a completely excised PB. After excluding metastatic lesions, we decided to perform only careful follow-up without chemotherapy. The follow-up at 12 months is negative. Although PB is a malignant tumor that requires a multidisciplinary treatment, the congenital cases seem to have a less aggressive biological behavior. The treatment, therefore, in case of complete resection, could be only surgical, followed by a careful follow-up. These forms are often associated with congenital BWS, but in our case the patient did not have the typical characteristics of the syndrome

    Sulla disposizione ottimale di frangiflutti galleggianti a catamarano combinati a convertitori di energia ondosa

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    - La ricerca in cui \ue8 inserito questo lavoro mira allo sviluppo di un dispositivo ibrido costituito da un convertitore di energia ondosa accoppiato ad un frangiflutti galleggiante. - Il frangiflutti, ancorato con pali, \ue8 costituito da elementi prefabbricati collegati rigidamente, in modo da formare una struttura a catamarano. - La configurazione migliore \ue8 la pi\uf9 stretta tra le due esaminate (8 m e 12 m di larghezza), che risulta molto efficiente pur senza essere soggetta a grosse sollecitazioni. - La struttura a catamarano \ue8 da preferire rispetto a quella tradizionale, a parit\ue0 di massa, sia in termini di trasmissione che di riflessione. - Il convertitore esaminato, idoneo ad integrare frangiflutti singoli, non \ue8 adatto ad integrare le strutture a catamarano

    UNA METODOLOGIA PER LA VALUTAZIONE DI CRITICITĂ€ E PRIORITĂ€ DI INTERVENTO: IL CASO DEL LITORALE VENETO

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    open3nobilancio sedimentario, litorale Veneto, erosione, allagamento costiero, gestione integrata della zona costiera.openRuol, Piero; Martinelli, Luca; Favaretto, ChiaraRuol, Piero; Martinelli, Luca; Favaretto, Chiar

    Coastal Flooding Hazard Due to Overflow Using a Level II Method: Application to the Venetian Littoral

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    In recent years, marine flooding and its impacts have become a question of growing interest, since coastal areas are the most heavily populated and developed land zones in the world. This paper presents a rapid tool for mapping at regional scale the hazard associated with coastal flooding due to overflow. The tool merges a recently developed numerical model that solves a simplified form of the Shallow-Water Equations and is suited for Graphic Processing Unit (GPU) acceleration, with a Level II reliability method that allows producing hazard maps of inland flooding propagation. The procedure was applied to two stretches of the Venetian littoral, i.e., Valle Vecchia and Caorle, located in the northern Adriatic Sea. The application includes the site descriptions and the resulting hazard maps that show the probability of failure in each point of the coast for a given inland inundation level

    Hydraulic Experiments on a Small-Scale Wave Energy Converter with an Unconventional Dummy Pto

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    This paper investigates on a Wave Energy Converter (WEC) named Energy & Protection, 4th generation (EP4). The WEC couples the energy harvesting function with the purpose of protecting the coast from erosion. It is formed by a flap rolling with a single degree of freedom around a lower hinge. Small-scale tests were carried out in the wave flume of the maritime group of Padua University, aiming at the evaluation of the device efficiency. The test peculiarity is represented by the system used to simulate the Power Take Off (PTO). Such dummy PTO permits a free rotation of two degrees before engaging the shaft, allowing the flap to gain some inertia, and then applying a constant resistive moment. The EP4 was observed to reach a 35% efficiency, under short regular waves. The effects, in terms of coastal protection, are small but not negligible, at least for the shortest waves

    Flooding of Piazza San Marco (Venice): Physical model tests to evaluate the overtopping discharge

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    This paper aims at evaluating the wave overtopping discharge over the pavement of "Piazza S. Marco" (Venice) in order to select the best option to mitigate the risk of flooding of the Piazza and to protect the monuments and historic buildings, e.g., the "Basilica S. Marco". In fact, the MO.S.E. (MOdulo Sperimentale Elettromeccanico) system is designed to keep the water level below a certain value, for the safety of the lagoon, but it does not guarantee the defence of the Piazza, where flooding is still possible, being its pavement locally much lower than the maximum expected water level. To completely defend the Piazza, specific additional works are planned to prevent the back-flow through the natural drainage system (now the primary pathway) or by filtration or by overtopping. This paper investigates on the overtopping mechanism, under conditions compatible with a fully operational MO.S.E. system, through 2-D experiments. The pavement of the Piazza is gently sloping towards the masonry quay which, in some parts is formed by 5 descending steps, and in some other parts, is just a vertical wall. Close to the "Marciana" Library, a critical part is present, with a slightly lower crest freeboard. In total, three cross-sections were examined in the 36 m long wave flume of the Padova University. The test programme includes 10 irregular wave attacks and three different water levels. The test results differ considerably from the results of the available formulas, since the investigated cross-sections by far exceed their range of applicability. The presence of the steps affects only the reflection coefficient rather than the overtopping discharges. In general, if the waves incident to the Piazza are higher than 40 cm, which is a possible scenario, some other adaptation works must be considered, such as the pavement rise, temporary barriers or the reduction of the waves impacting the quay through, for instance, floating breakwaters

    Genetic Features of Metachronous Esophageal Cancer Developed in Hodgkin's Lymphoma or Breast Cancer Long-Term Survivors: An Exploratory Study.

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    Background Development of novel therapeutic drugs and regimens for cancer treatment has led to improvements in patient long-term survival. This success has, however, been accompanied by the increased occurrence of second primary cancers. Indeed, patients who received regional radiotherapy for Hodgkin's Lymphoma (HL) or breast cancer may develop, many years later, a solid metachronous tumor in the irradiated field. Despite extensive epidemiological studies, little information is available on the genetic changes involved in the pathogenesis of these solid therapy-related neoplasms. Methods Using microsatellite markers located in 7 chromosomal regions frequently deleted in sporadic esophageal cancer, we investigated loss of heterozygosity (LOH) and microsatellite instability (MSI) in 46 paired (normal and tumor) samples. Twenty samples were of esophageal carcinoma developed in HL or breast cancer long-term survivors: 14 squamous cell carcinomas (ESCC) and 6 adenocarcinomas (EADC), while 26 samples, used as control, were of sporadic esophageal cancer (15 ESCC and 11 EADC). Results We found that, though the overall LOH frequency at the studied chromosomal regions was similar among metachronous and sporadic tumors, the latter exhibited a statistically different higher LOH frequency at 17q21.31 (p = 0.018). By stratifying for tumor histotype we observed that LOH at 3p24.1, 5q11.2 and 9p21.3 were more frequent in ESCC than in EADC suggesting a different role of the genetic determinants located nearby these regions in the development of the two esophageal cancer histotypes. Conclusions Altogether, our results strengthen the genetic diversity among ESCC and EADC whether they occurred spontaneously or after therapeutic treatments. The presence of histotype-specific alterations in esophageal carcinoma arisen in HL or breast cancer long-term survivors suggests that their transformation process, though the putative different etiological origin, may retrace sporadic ESCC and EADC carcinogenesis

    Congenital pancreatoblastoma: a case report

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    The literature describes 15 cases of congenital pancreatoblastoma (PB): 5 had prenatal diagnosis, none had metastases at diagnosis, 7 were associated with BeckwitheWiedemann syndrome (BWS). In 13 cases resection was radical, while in 2 there were macroscopic residues. Only one patient underwent chemotherapy after distant recurrence. All children are alive except one who died because of problems related to BWS. Our goal is to describe the approach adopted in an infant with congenital PB treated in our center. After a prenatal third semester diagnosis of abdominal anechoic lesion, the radiological investigations (ultrasound, MRI) performed at birth described a cystic lesion of unclear nature. We proceeded to laparoscopic exploration, transformed into open approach after the detection of a lesion located in the body of the pancreas; this lesion was resected, preserving the head and tail of pancreas. The histological diagnosis showed a completely excised PB. After excluding metastatic lesions, we decided to perform only careful follow-up without chemotherapy. The follow-up at 12 months is negative. Although PB is a malignant tumor that requires a multidisciplinary treatment, the congenital cases seem to have a less aggressive biological behavior. The treatment, therefore, in case of complete resection, could be only surgical, followed by a careful follow-up. These forms are often associated with congenital BWS, but in our case the patient did not have the typical characteristics of the syndrome
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