Modelling of dynamic reliability stages of a ship propulsion system with safety and exhaust emission

U radu je prikazana uspješnost primjene spoja Markovljevih lanaca i sustavno dinamičkog modeliranja pri istraživanju problema pouzdanosti tehničkih sustava. Prikazan je originalni matematički model brodskog porivnog sustava sa šest stanja. Sam spoj Markovljevog modela sa sustavno dinamičkim simulacijskim modelom, doprinosi originalnosti rješavanja problema pouzdanosti brodskog porivnog sustava. Primjena sustavno dinamičkog simulacijskog modela omogućuje kvantifikaciju parametara efektivnosti održavanja strukture sustava i utječe na poboljšanje pouzdanosti i raspoloživosti konkretnog tehničkog sustava. Izrađeni simulacijski model simuliran je pomoću simulacijskog programa POWERSIM. Korištena je baza podataka programskog paketa održavanja AMOS, koji se koristi na M/B Explorer. Na temelju dobivenih rezultata može se planirati te pravodobno i učinkovito utjecati na kvalitetnije upravljanje brodskim porivnim sustavima.This paper elaborates on the efficacy of application of the combination of Markov chains and systematic-dynamic modelling during research on technical systems reliability problem. The original mathematical model of a ship propulsion system has been shown in six stages. The very combination of Markov model with systematic-dynamic model contributes to original solution to the problem of the ship propulsion system reliability. By the application of systematic-dynamic simulation model it is possible to quantify the system structure maintenance efficacy parameters and enable better reliability and availability of a specific technical system. Simulation programme POWERSIM has been used to simulate the subject simulation model. AMOS maintenance programme package data base has been applied, which is being used on board the m/v Explorer. On the basis of the results obtained it is possible to plan and timely and efficiently influence a higher quality ship propulsion systems management

Bolna dijabetička polineuropatija

Diabetic polyneuropathy represents mostly symmetrical damage of the peripheral nerves associated with diabetes mellitus. Clinical picture depends on the duration of diabetes, glucose blood level and insulin use. Distal symmetric polyneuropathy is the most common neuropathy of diabetes. It presents with sensory symptoms, paresthesiae and fingers pain in the hands and legs. Isolated forms of DPN are asymmetrical (focal or multifocal) and autoimmune form.Dijabetička polineuropatija kao jedna od komplikacija dijabetesa melitusa klinički se manifestra kao simetrično oštećenje strukture i funkcije perifernih živaca. Stupanj oštećenja i klinička slika ovise o trajanju dijabetesa, terapiji koju bolesnici uzimaju te vrijednostima glukoze u krvi. Distalna simterična polineuropatija kao najčešća komplikacija dijabetesa klinički se prezentira senzornim simptomima, parestezijama i bolovima u prstima ruku i nogu. Izolirane forme disalne dijabetičke polineuropatije mogu biti i asimterične (fokalne i multifokalne) i autoimune forme

Bolna dijabetička polineuropatija

Diabetic polyneuropathy represents mostly symmetrical damage of the peripheral nerves associated with diabetes mellitus. Clinical picture depends on the duration of diabetes, glucose blood level and insulin use. Distal symmetric polyneuropathy is the most common neuropathy of diabetes. It presents with sensory symptoms, paresthesiae and fingers pain in the hands and legs. Isolated forms of DPN are asymmetrical (focal or multifocal) and autoimmune form.Dijabetička polineuropatija kao jedna od komplikacija dijabetesa melitusa klinički se manifestra kao simetrično oštećenje strukture i funkcije perifernih živaca. Stupanj oštećenja i klinička slika ovise o trajanju dijabetesa, terapiji koju bolesnici uzimaju te vrijednostima glukoze u krvi. Distalna simterična polineuropatija kao najčešća komplikacija dijabetesa klinički se prezentira senzornim simptomima, parestezijama i bolovima u prstima ruku i nogu. Izolirane forme disalne dijabetičke polineuropatije mogu biti i asimterične (fokalne i multifokalne) i autoimune forme

Mechanical ventilation in chronic obstructive pulmonary disease patients, noninvasive vs. invasive method (randomized prospective study) [Usporedba neinvazivne i invazivne umjetne ventilacije kod bolesnika s kroničnom opstruktivnom plućnom bolesti: prospektivna randomizirana studija]

Acute respiratory failure due to chronic obstructive pulmonary disease (COPD) presents an increasing problem throughout the world. The aim of this study was to compare invasive and non-invasive mechanical ventilation (MV) for patients with COPD. A prospective, randomized trial was performed in a multidisciplinary intensive care unit for the period of 36 months and included 156 patients with COPD. MV procedure was performed using standard methods, and was applied as either invasive MV (IMV) or noninvasive MV (NIMV). Patients were randomized in two groups for application of MV using closed, nontransparent envelops. Comparison was made based on patient characteristics, objective parameters on admission and 1h, 4h, 24h, and 48h after admission and based on treatment outcome. We have confirmed that NIMV method is superior to IMV for patients with COPD. MV duration NIMV:IMV was 94:172 hours, p<0.001, time spent in Intensive Care Unit 120:223 hours, p<0.001. Ventilator associated pneumonia 5(6%):29(37%), p<0.001.The advantage of NIMV in COPD patients, especially in the early stages was confirmed

Modelling the Stages of Turbocharger Dynamic Reliability by Application of Exploitation Experience

Turbocharger is an important part of marine diesel engine installed as main propulsion on board. It is in operation from the outset and throughout the marine diesel engine exploitation. In order to meet high reliability criteria, a combination of mathematical, IT and simulation methods should be used. The original mathematical model of turbocharger has been shown in five stages. The paper presents database link from the AMOS maintenance software package, a mathematical model elaborated by using Markov chains and a systematic-dynamic simulation model elaborated in the POWERSIM simulation programme. Results will be used to monitor and predict reliability and availability of turbocharger in ship’s propulsion system

Prognostic value of left ventricular longitudinal strain in patients with aortic stenosis

Left ventricular (LV) hypertrophy in patients with aortic stenosis (AS) is an adaptive mechanism that tries to maintain left ventricular systolic function despite obstruction.1 The appearance of myocardial fibrosis (MF) is a turning point from adaptive hypertrophy to maladaptation, that changes ventricular function and represents the basis for development of ventricular arrhythmias. There are two types of MF: reversible interstitial MF in early stage, and irreversible replacement MF in the later stage of disease. MF occupies LV midwall, usually in LV posterobasal part. Cardiac magnetic resonance (CMR) by late gadolinium enhancement (LGE) is the „gold standard“ in diagnosis of replacement MF. Positive LGE results indicate significantly greater risk of adverse outcome than it is in patients without MF. Echocardiography suggests the presence of MF with significant reliability, because global longitudinal strain (GLS) shows good correlation with results of CMR. Consequently, GLS can serve as a surrogate marker of MF and an indicator of adverse events in AS.2-4 MF mostly influences LV longitudinal function, while circumferential and radial deformation are less modified. In severe compensated AS circumferential deformation and apical rotation (ApR) are increased, what is likely a compensative mechanism for keeping cardiac output. The increased ApR is also associated with worse survival. With disease progression these compensative changes disappear. Mechanical dispersion (MD) is an indicator of contractile heterogeneity caused by fibrosis. Increased MD demonstrates significant association with mortality and can serve as an additional prognostic parameter. Along with more extensive MF the risk for sudden cardiac death increases what raises the question of the benefit of cardioverter-defibrillator. In conclusion, impaired GLS suggests MF, what must be confirmed by CMR. MF classifies the patients with severe asymptomatic AS into the group with increased risk of adverse outcome. Therefore, it is to be expected that these new facts will result in new guidelines for treatment of severe asymptomatic AS