Ship Hull Representation by Non-Uniform Rational B-Spline Surface Patches

The purpose of this work is to propose a new method for representing the ship hull shape with mathematic surfaces so that geometric data can be generated for any point on the hull where required to assist the production process. An extensive survey of previous work is presented covering both the use of parametric curves and surfaces to model the ship hull and also the most relevant software systems developed for that purpose. The main methods and algorithms available for the generation and edition of curves and surfaces are presented and compared taking into consideration the intended application. From the analysis of the formulations available it was concluded that the most adequate one, which however had not yet been extensively used to model ship hulls was the Non-Uniform Rational B-Splines (NURBS), due to the potential of their capability to represent exactly conic curves and surfaces. Therefore these surfaces were selected as the basis of the method developed in this thesis. A procedure is proposed for the representation of a given hull form in a two step approach, creating first a wireframe model over which the surface patches are generated. Both curves and surfaces are based on the NURBS formulation. To create the wireframe model, first a set of longitudinal boundary lines is selected, dividing the surface into areas of similar shape. Then, these lines are fitted by curves and faired to some extent. Next, transverse sections are defined and split by the boundary lines. Surface patches are then generated over the transverse section curves within the limits of each patch. Finally, to obtain the traditional representation of the ship surface by transverse sections, buttocks and waterlines, contour lines are generated for constant values of x, y and z coordinates. A computer system has been developed incorporating an interface that allows the visualization of the curves and surfaces being modeled. The system incorporates several algorithms for generation and edition of curves and surfaces, in addition to the main contribution of this thesis which is the use of NURBS to represent the ship hull surface. The system also incorporates curve and surface analysis tools and some basic fairing algorithms so that during the several steps of the creation of the model, the fairness of the curves and surfaces can be evaluated and improved to some extent. The procedure is tested and compared with an existing commercial system through some application examples, of a complete hull and in more detail in the bow region, showing that good results can be obtained with the system presented here

Patients with multiple sclerosis do not necessarily consume more alcohol or tobacco than the general population

Peer reviewedPublisher PD

Porphyrin-Based Metal-Organic Frameworks as Heterogeneous Catalysts in Oxidation Reactions

Porphyrin-based Metal-Organic Frameworks (Por-MOFs) constitute a special branch of the wide MOF family that has proven its own value and high potential in different applications. In this mini-review the application of these materials as catalysts in oxidation reactions is highlighted

Neuroretinitis caused by Bartonella henselae: case report

Bolest mačjeg ogreba je zarazna bolest uzrokovana bakterijom Bartonella henselae, a obilježena je regionalnom limfadenopatijom i vrućicom. Iako i drugi organi mogu biti zahvaćeni, oči su rijetko zahvaćene (5% - 10%), što se može manifestirati kao neuroretinitis. Prikazujemo slučaj 11-godišnjeg dječaka primljenog na hitni odjel zbog gubitka vida na desnom oku, što je otkriveno probirnim testiranjem vida. Oftalmološki pregled pokazao je otok diska, peripapilarna mikrokrvarenja i edem makule s eksudatima bogatim lipidima, što je ukazivalo na zvjezdastu makulu. Serološki testovi pokazali su povišeni titar protutijela na Bartonella henselae. Bolesnik je liječen rifampicinom i doksiciklinom, uz optimalan terapijski odgovor. Neuroretinitis je rijetka manifestacija infekcije bakterijom Bartonella henselae i na njega treba posumnjati u svakog bolesnika u kojega se uz gubitak vidne oštrine utvrdi oticanje diska, zvjezdasti eksudati makule te kontakt s mačkama u anamnezi. Kod većine bolesnika predinfekcijska vidna funkcija oporavi se u većoj mjeri ili potpuno, međutim, u manjeg broja bolesnika s naročito teškim neuroretinitisom mogu ostati posljedice u funkciji vida. Nema randomiziranih istraživanja učinkovitosti liječenja, no čini se da antibiotska terapija rifampicinom i doksiciklinom skraćuje tijek bolesti i ubrzava oporavak vida.Cat scratch disease is an infectious disease caused by Bartonella henselae characterized by regional lymphadenopathy and fever. Although it may involve other organs, ocular involvement is rare (5%-10%) and may manifest as neuroretinitis. We present a case of an 11-year-old patient admitted to the emergency department because of vision loss on the right eye, detected on a vision screening test. Ophthalmological evaluation showed disc swelling, peripapillary microhaemorrhages and macular oedema with lipid-rich exudates, suggestive of the macular star pattern. Serological studies revealed elevated titre of antibodies to Bartonella henselae. The patient was treated with rifampicin and doxycycline, with optimal response. Neuroretinitis is an uncommon manifestation of Bartonella henselae infection and should be suspected in any patient presenting loss of visual acuity, along with the fi nding of disc swelling, macular star exudates, and a history of contact with cats. Most patients recover most or all of their pre-infection visual function, however, a small subset of patients with particularly severe neuroretinitis may be left with optic sequelae. There are no randomized trials on the eff ectiveness of treatment but antibiotic therapy with rifampicin and doxycycline seems to shorten the course of the disease and hasten visual recovery

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Optimisation of Perioperative Cardiovascular Management to Improve Surgical Outcome II (OPTIMISE II) trial: study protocol for a multicentre international trial of cardiac output-guided fluid therapy with low-dose inotrope infusion compared with usual care in patients undergoing major elective gastrointestinal surgery.

INTRODUCTION: Postoperative morbidity and mortality in older patients with comorbidities undergoing gastrointestinal surgery are a major burden on healthcare systems. Infections after surgery are common in such patients, prolonging hospitalisation and reducing postoperative short-term and long-term survival. Optimal management of perioperative intravenous fluids and inotropic drugs may reduce infection rates and improve outcomes from surgery. Previous small trials of cardiac-output-guided haemodynamic therapy algorithms suggested a modest reduction in postoperative morbidity. A large definitive trial is needed to confirm or refute this and inform widespread clinical practice. METHODS: The Optimisation of Perioperative Cardiovascular Management to Improve Surgical Outcome II (OPTIMISE II) trial is a multicentre, international, parallel group, open, randomised controlled trial. 2502 high-risk patients undergoing major elective gastrointestinal surgery will be randomly allocated in a 1:1 ratio using minimisation to minimally invasive cardiac output monitoring to guide protocolised administration of intravenous fluid combined with low-dose inotrope infusion, or usual care. The trial intervention will be carried out during and for 4 hours after surgery. The primary outcome is postoperative infection of Clavien-Dindo grade II or higher within 30 days of randomisation. Participants and those delivering the intervention will not be blinded to treatment allocation; however, outcome assessors will be blinded when feasible. Participant recruitment started in January 2017 and is scheduled to last 3 years, within 50 hospitals worldwide. ETHICS/DISSEMINATION: The OPTIMISE II trial has been approved by the UK National Research Ethics Service and has been approved by responsible ethics committees in all participating countries. The findings will be disseminated through publication in a widely accessible peer-reviewed scientific journal. TRIAL REGISTRATION NUMBER: ISRCTN39653756.The OPTIMISE II trial is supported by Edwards Lifesciences (Irvine, CA) and the UK National Institute for Health Research through RMP’s NIHR Professorship

Automatic feeding of screw machines

Dissertação de Mestrado Integrado em Engenharia Mecânica apresentada à Faculdade de Ciências e TecnologiaNo presente contexto industrial assiste-se a uma constante e acelerada evolução de tecnologias, conceitos e técnicas com vista a dar resposta a uma enorme competitividade e satisfação da procura exigida, sendo a indústria automóvel um dos maiores motores dessa evolução.A competitividade requere às empresas elevados grau de qualidade e de respostas imediatas. Como consequência, há uma crescente complexidade e importância das máquinas e processos produtivos, tornando cada vez mais dispendiosas as paragens de produção. Neste sentido, as empresas procuram desenvolver sistemas de gestão de manutenção que permitam reduzir não só o número de paragens nos processos, como também a duração de cada paragem e, consequentemente, todos os custos associados. A dissertação apresentada tem como objetivo a melhoria produtiva no processo de alimentação autónoma de parafusos nas máquinas de roscagem. Trata-se de um processo difícil e personalizado, onde a flexibilidade é um aspeto fulcral. Assim é apresentado o estudo de um dos sistemas de maior preocupação na alimentação desta maquinaria, estudando-o e encontrando o gargalo do sistema, para encontrar medidas corretivas para o diminuir e assim aumentar a sua cadência, flexibilidade e fiabilidade. Em paralelo, são também estudadas soluções de substituição para o sistema de orientação e alimentação em estudo, encontrando assim soluções mais flexível, com menores e menos paragens, e para uma adaptação mais rápida, tanto para novas referencias como também para outras funções.In the present industrial context, there is a constant and accelerated evolution of technologies, concepts and techniques in order to respond to the enormous competitiveness and satisfaction of demand demanded, with the automotive industry being one of the main drivers of this evolution.Competitiveness requires companies to achieve high quality and immediate responses. As a consequence, there is a growing complexity and importance of machines and production processes, making production stoppages increasingly costly. In this sense, companies seek to develop maintenance management systems that reduce not only the number of stops in the processes, but also the duration of each stop and, consequently, all associated costs.The dissertation presented has as objective the productive improvement in the process of autonomous feeding of screws in the threading machines. It is a difficult and personalized process, where flexibility is a key aspect. Thus, it is presented the study of one of the systems of greatest concern in the feeding of this machinery, studying it and finding the bottleneck of the system, to find corrective measures to reduce it and thus increase its cadence, flexibility and reliability.In parallel, replacement solutions are also studied for the orientation and feeding system under study, thus finding more flexible solutions, with smaller and less stops, and for a faster adaptation, for new references as well as for other functions. With this dissertation, will be implementing improvements in the system and compare with the new solutions