73 research outputs found
Scour depth development at piles of different height under the action of cyclic (tidal) flow
No full textThe impact of cyclic (tidal) flow on scour at cylindrical monopiles in the live-bed regime has been examined on the basis of results from mobile sand bed flume experiments. Four tests were conducted with four 0.114 m diameter piles of differing stickup height placed across the 4 m wide test section of the Fast Flow Facility. The tidal tests Tide01, Tide02 and Tide03 had the same peak current speed in forward and reverse direction with different cycle periods to examine the role of cycle length on scour. The period in Tide01 was approximately halved in Tide02 and doubled in Tide03. A unidirectional test Uni01 was run for comparative purposes. The results have shown how the cycle length adopted in testing has a key controlling effect on the scour achieved in a fixed number of cycles. The scour data measured on two sides of the piles at 1 Hz are plotted both in time-series format and pairwise to illustrate the cyclic nature of the scour development and recycling of sediment within the scour hole. The effective work method of Link et al. (2016) provides a good correlation for the dimensionless scour depth. The cyclic behaviour of the scour difference across the pile diameter has been analysed in terms of a basal slope and the magnitude of the scour depth, akin to geotechnical testing of monopile response to cyclic loads. Comparison with field measurements of scour shows that the cyclic tests can achieve non-dimensional scour depths found in the field. A progressive reduction in the slope angle is demonstrated for increasing number of cycles but further investigation of the different angle observed in field and laboratory is required. Finally the effect of pile stickup height is evaluated using both published and the current data, and a modified value of the Sumer and Fredsøe coefficient is proposed for undirectional and tidal scour
Optical and Morphological Characterization of Nanoscale Oxides Grown in Low-Energy H+-Implanted c-Silicon
No full textNanoscale oxides grown in c-silicon, implanted with low-energy (2 keV) H+ ions and fluences ranging from 1013 cm−2 to 1015 cm−2 by RF plasma immersion implantation (PII), have been investigated. The oxidation of the implanted Si layers proceeded in dry O2 at temperatures of 700 °C, 750 °C and 800 °C. The optical characterization of the formed Si/SiOx structures was conducted by electroreflectance (ER) and spectroscopic ellipsometric (SE) measurements. From the ER and SE spectra analysis, the characteristic energy bands of direct electron transitions in Si are elaborated. The stress in dependence on hydrogenation conditions is considered and related to the energy shifts of the Si interband transitions around 3.4 eV. Silicon oxides, grown on PII Si at a low H+ fluence, have a non-stoichiometric nature, as revealed by IR-SE spectra analysis, while with an increasing H+ fluence in the PII Si substrates and/or the subsequent oxidation temperature the stoichiometric Si-O4 units in the oxides become predominant. The development of surface morphology is studied by atomic force microscopy (AFM) imaging. Oxidation of the H+-implanted Si surface region flattens out the surface pits created on the Si surface by H+ implants. Based on the evaluation of the texture index and mean fractal dimension, the isotropic and self-similar character of the studied surfaces is emphasized
Algorithmic program - support in learning of ‘handspring forward with 1½ tucked salto forward’ on vault
No full textThis paper aimed to increase the learning efficiency of 'Handspring forward with 1½ tucked salto forward’ on vault by exploiting gymnasts’ internal factors of performance and shortening the assimilation time of technical elements using algorithmic programs. Experimental research involves the selection and adjustment of the most efficient means for specific physical and technical training requiered in learning 'Handspring forward with 1½ tucked salto forward’ on vault. This paper also brings evidence to evaluate in an objective and gradual manner the technical preparation o f gymnasts through all three series of algorithmic programme and finds significant and consistent differences between gymnasts’ execution in initial testing relative to final testing. This implies that learning of any elements should be based on algorithmi c program to ensure the perfect execution. The difference between the performance of the two groups of gymnasts in executing 'Handspring forward with 1½ tucked salto forward’ on vault indicates that the proposed objective has been achieved. The results obtained by the two tested groups of gymnasts have shown that algorithmic programme that I have created makes a huge difference in performance score difference which can mean an Olympic medal.
Keywords: Algorithmic programme, technical elements, vault</jats:p
Central pancreatectomy - indications revisited
No full textInstitutul Clinic Fundeni, București, Al XI-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova și cea de-a XXXIII-a Reuniune a Chirurgilor din Moldova „Iacomi-Răzeșu” 27-30 septembrie 2011Pancreatectomia alternativă la rezecțiile standard (duodenopancreatectomia cefalica și
pancreatectomia distală) pentru leziuni situate la nivelul istmului și corpului de pancreas. Principalul avantaj este reprezentat de conservarea atât a
funcției exocrine cât și a celei endocrine a pancreasului. Dezavantajul major este reprezentat de morbiditatea postoperatorie crescută, reprezentată în
principal de fistula pancreatică. Cele mai frecvente indicații ale pancreatectomiei centrale sunt reprezentate de tumorile benigne și cu potențial redus
de malignizare. Chiar dacă acest procedeu chirurgical este contraindicat în carcinomul ductal de pancreas, totuși, o serie de alte malignități speciale ale
pancreasului cum ar fi metastazele pancreatice ale altor neoplazii sau pancreatoblastomul pot beneficia, în anumite situații, de acest tip de intervenție chirurgicală. Deși nu este o procedură chirurgicală foarte frecvent utilizată, pancreatectomia centrală, își găsește locul în arsenalul rezectiilor pancreatice.Central pancreatectomy has emerged as a pancreas-sparing alternative technique to standard pancreatic resections (i.e. pancreatico-duodenectomy and
distal pancreatectomy) for pancreatic lesions located to the isthmus and body. The main advantage is related to a better preservation of both exocrine
and endocrine pancreatic functions. Conversely, the major concern is related to the high postoperative morbidity, mainly related to the postoperative
pancreatic fistula rate. The most frequent reported indications for central pancreatectomy are represented by benign and low-malignant lesions of the
pancreas. Although central pancreatectomy is not indicated for ductal adenocarcinoma of the pancreas, however, for certain special malignancies of
the pancreas (i.e. metastasis to the pancreas of others neoplasia, pancreatoblastoma), central pancreatectomy has been proven to be a safe operation.
Although central pancreatectomy is not a frequent operation, it should be included in pancreatic surgeons’ armamentarium for certain indications
Surgical treatment of chronic pancreatitis a 14 years single center experience
No full textAl XI-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova și cea de-a XXXIII-a Reuniune a Chirurgilor din Moldova „Iacomi-Răzeșu” 27-30 septembrie 2011Tratamentul chirurgical al pancreatitei cronice este indicat la pacienții cu durere persistentă în ciuda tratamentului medicamentos sau endoscopic,
sau în cazul prezenței complicațiilor.Obiectiv: Acest studiu evaluează experiența unui singur centru în ceea ce privește managementul chirurgical al
pancreatitei cronice pe o perioadă de 14 ani, cu privire la indicație,tehnica chirurgicală, rezultate imediate și tardive.Material și metodă: Au fost studiați
265 de pacienți ce au suferit intervenții chirurgicale pentru pancreatita cronicã între anii 1995 și 2008. Rezultatele tardive postoperatorii au fost evaluate
prin sondaj direct, cu o urmãrire medianã de 40 de luni.Rezultate: 265 de pacienți au suferit 275 de intervenții chirugicale pentru pancreatita cronicã
având ca indicțtie principalã durerea abdominalã (46,8%), urmatã de suspiciunea de malignizare 24,8 % și episoade de pancreatitã acutã recurentã
18,6%. Rezecții 54,5% (150), proceduri de drenaj1,09% (3), derivatii, proceduri de neurolizã 44,36% (122) silaparotomii exploratorii 3,27% (9) au fost
efectuate cu o morbiditate totalã de 22 % și o mortalitate imediatã de 2,64%.Dupã o urmãrire medianã de 40 de luni s-au obținut informații pentru
137 de pacienți (51,69%) cu o supraviețuire actuarialã la 5 ani de 74,7% și îmbunãtãțirea calității vieții la majoritatea pacienților, în special la pacienții
rezecati. Concluzie: Rezultatele noastre sugereazã că în cazul pancreatitei cronice tipul interventiei chirurgicale trebuie individualizat (rezectie vs drenaj)
și operațiile conservatoare (organ sparing) sunt eficiente și sigure în tratamentul pe termen lung al durerii și al complicatiilor pancreatitei cronice. Background: Operative treatment of chronic pancreatitis isindicated for patients with intractable pain after failed medicaland endoscopic treatment, or
in the presence of complicationsof the disease.Aims: This study evaluates a single-center experience withoperative management of chronic pancreatitis
over a periodof time of 14 years, regarding indication, surgical technique,early and late results.Patients and Methods: The records of 265 consecutive
patientswho underwent surgery for chronic pancreatitis between 1995and 2008 were retrospectively reviewed and analyzed. Longtermoutcomes were
assessed by patient survey, with a medianfollow-up of 40 months.Results: 265 patients underwent 275 operations for chronicpancreatitis with the main
indication abdominal pain(46,8%), followed by suspected malignancy in 24,8 % andrecurrent episodes of acute pancreatitis in 18,6%. Resectionprocedures
54,5% (150), drainage procedures 1,09% (3), bypassand denervation procedures 44,36% (122) andexploratory laparotomy 3,27% (9) were performed
with anoverall morbidity of 22 % and an in-hospital mortality rateof 2,64%. After a median follow-up of 40 months survivalinformation was available for
137 patients (51,69%) with aCorresponding author:225-and actuarial survival rate of 74,7% and quality of lifeimprovement in most patients, especially
in the resectedgroup.Conclusion: Our results suggest that in chronic pancreatitisthe type of surgery has to be individualized in each patient(resection
VS drainage) and organ preserving operations aresafe and effective in providing long-term pain relief and in treating CP-related complications.Background: Operative treatment of chronic pancreatitis is indicated for patients with intractable pain after failed medical and endoscopic treatment or in the presence of complications of the disease.Aims: This study evaluates a single-center experience with operative management of chronic pancreatitis over a period of time of 14 years, regarding indication, surgical technique, early and late results. Patients and Methods: The records of 265 consecutive patients who underwent surgery for chronic pancreatitis between 1995and 2008 were retrospectively reviewed and analyzed. Long-term outcomes were
assessed by the patient survey, with a median follow-up of 40 months. Results: 265 patients underwent 275 operations for chronic pancreatitis with the main indication abdominal pain(46,8%), followed by suspected malignancy in 24,8 % and recurrent episodes of acute pancreatitis in 18,6%. Resection procedures 54,5% (150), drainage procedures 1,09% (3), bypass and denervation procedures 44,36% (122) and exploratory laparotomy 3,27% (9) were performed with an overall morbidity of 22 % and an in-hospital mortality rate of 2,64%. After a median follow-up of 40 months, survival information was available for 137 patients (51,69%) with a corresponding author: the 225-and actuarial survival rate of 74,7% and quality of life-improvement in most patients, especially
in the resected group. Conclusion: Our results suggest that in chronic pancreatitis the type of surgery has to be individualized in each patient(resection VS drainage) and organ-preserving operations are safe and effective in providing long-term pain relief and in treating CP-related complications
Multi-stage pulsed laser deposition of aluminum nitride at different temperatures
No full textWe report on multi-stage pulsed laser deposition of aluminum nitride (AlN) on Si (1 0 0) wafers, at different temperatures. The first stage of deposition was carried out at 800 °C, the optimum temperature for AlN crystallization. In the second stage, the deposition was conducted at lower temperatures (room temperature, 350 °C or 450 °C), in ambient Nitrogen, at 0.1 Pa. The synthesized structures were analyzed by grazing incidence X-ray diffraction (GIXRD), transmission electron microscopy (TEM), atomic force microscopy and spectroscopic ellipsometry (SE). GIXRD measurements indicated that the two-stage deposited AlN samples exhibited a randomly oriented wurtzite structure with nanosized crystallites. The peaks were shifted to larger angles, indicative for smaller inter-planar distances. Remarkably, TEM images demonstrated that the high-temperature AlN "seed" layers (800 °C) promoted the growth of poly-crystalline AlN structures at lower deposition temperatures. When increasing the deposition temperature, the surface roughness of the samples exhibited values in the range of 0.4-2.3 nm. SE analyses showed structures which yield band gap values within the range of 4.0-5.7 eV. A correlation between the results of single- and multi-stage AlN depositions was observed. © 2015 Elsevier B.V. All rights reserved
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