The Analyses of the Failures of Hull Structure Plating Caused by Corrosion

There are a lot of different factors of hull structure degradation such as cracks, damage, fatigue or corrosion. Fatigue and corrosion were the most thoroughly examined in the previous studies. Corrosion is a more dominant form of degradation that causes the reduction of the original thickness of materials over time, which can be expressed through weight loss, in millimeter or percentage of thickness diminution of steel plates. Corrosion process can reduce carrying capacity and longitudinal strength of vessels, cause different types of failures or lead to the pollution of surrounding areas. This study analyzes the corrosion of a structural element of a fuel tank on the old bulk carrier that has been in operation for 25 years. The database consists of thickness measures expressed as percentage of diminution of the original plate thickness and the analysis of the chemical composition of a corroded and replaced steel plate. The study examined the total of 350 measured data after 5, 10, 15, 20 and 25 years of ship exploitation. Similarly, the research observed the chemical composition of the replaced steel plate. Linear corrosion models were developed while the chemical composition was analyzed by means of Energy Dispersive X-ray analysis of the samples from both sides of the corroded plate. The obtained results indicated that the degree of corrosion significantly varies depending on the environment of the plate. Furthermore, the formed linear corrosion model adequately follows the empirical data and value of 1,55 %/year

Recombinant factor Vlla therapy in a patient on long term anticoagulant treatment with a bleeding and acute subdural hematoma

In this paper we report on the successful correction of a coagulopathy with activated recombinant factor seven (rFVIIa) therapy which enabled surgical removal of a life threatening subdural hematoma. The severe coagulopathy developed due to long term warfarin therapy, which followed heart valvular reconstruction and replacement. The coagulopathy failed to improve following fresh frozen plasma and vitamin K therapy. Activated recombinant factor VII therapy became the treatment of choice, which enabled the life saving surgical removal of the subdural hematoma

Recombinant factor Vlla therapy in a patient on long term anticoagulant treatment with a bleeding and acute subdural hematoma

In this paper we report on the successful correction of a coagulopathy with activated recombinant factor seven (rFVIIa) therapy which enabled surgical removal of a life threatening subdural hematoma. The severe coagulopathy developed due to long term warfarin therapy, which followed heart valvular reconstruction and replacement. The coagulopathy failed to improve following fresh frozen plasma and vitamin K therapy. Activated recombinant factor VII therapy became the treatment of choice, which enabled the life saving surgical removal of the subdural hematoma

Metaheuristic approach for solving one class of optimization problems in transport

Problem dodele vezova obuhvata nekoliko važnih odluka koje je potrebno doneti da bi se dosegla maksimalna efikasnost luke. U luci, menadžeri terminala treba da dodele slobodne vezove brodovima koji su najavili dolazak...Berth Allocation Problem incorporates some of the most important decisions that have to be made in order to achieve maximum eciency in a port. Terminal manager of a port has to assign incoming vessels to the available berths, where they will be loaded/unloaded in such a way that some objective function is optimized. It is well known that even the simpler variants of Berth Allocation Problem are NP-hard, and thus, metaheuristic approaches are more convenient than exact methods, because they provide high quality solutions in reasonable computational time. This study considers two variants of the Berth Allocation Problem: Minimum Cost Hybrid Berth AllocationProblem (MCHBAP) and Dynamic Minimum Cost Hybrid Berth AllocationProblem (DMCHBAP), both with xed handling times of vessels. Objective function to be minimized consists of the following components: costs of positioning, speeding up or waiting of vessels, and tardiness of completion for all vessels. Having in mind that the speed of nding high-quality solutions is of crucial importance for designing an ecient and reliable decision support system in container terminal, metaheuristic methods represent the natural choice when dealing with MCHBAP and DMCHBAP. This study examines the following metaheuristic approaches for both types of a given problem: two variants of the Bee Colony Optimization (BCO), two variants of the Evolutionary Algorithm (EA), and four variants of Variable Neighborhood Search (VNS). All metaheuristics are evaluated and compared against each other and against exact methods integrated in commercial CPLEX solver on real-life instances from the literature and randomly generated instances of higher dimensions. The analysis of the obtained results shows that on real-life instances all metaheuristics were able to nd optimal solutions in short execution times. Randomly generated instances were out of reach for exact solver due to time or memory limits, while metaheuristics easily provided high-quality solutions in short CPU time in each run. The conducted computational analysis indicates that metaheuristics represent a promising approach for MCHBAP and similar problems in maritime transportation..

Clinical significance of intraabdominal pressure and abdominal perfusion pressure in patients with acute abdominal syndrome

Elevated intraabdominal pressure (IAP) has been claimed to play a role in abdominal compartment syndrome. We assessed the correlation between the values of IAP, abdominal perfusion pressure (APP) and clinical scoring systems including SIRS, MODS and APACHE II and the patients\u27 survival rate in patients admitted to the ICU with acute abdomen due to ileus, intestinal perforation, peritonitis and trauma. We measured IAP and APP in 50 surgical patients. In this study the IAP was measured in a non-invasive manner via urinary bladder pressure. The APP was calculated as the difference between mean arterial pressure and IAP values. A significantly higher IAP was found in the non-survivors\u27 group in comparison with the survivors\u27 group. On the other hand, the APP inversely correlated with disease severity scores including SIRS, MODS and APACHE II, whereas IAP values did not show any correlation to these clinical parameters. These findings suggest that IAP and APP may be useful tools in the clinical evaluation of patients with acute abdomen

ANALYSIS OF CORROSION DEPTH PERCENTAGE ON THE INNER BOTTOM PLATES OF AGING BULK CARRIERS WITH AN AIM TO OPTIMIZE CORROSION MARGIN

To ensure the better structural integrity and maximum safety of bulk carriers in the ship design phase, an appropriate corrosion margin is introduced by the classification societies, which should enable the exploitation of ships during the projected 25-year life cycle. The new Common Structural Rules introduce even higher corrosion margin value to ensure the structural integrity of the ship. This directly affects the increase in hull weight and thus the need for more total installed power and higher fuel consumption. Higher fuel consumption results in increased emissions which directly affects environmental pollution. For these reasons, efforts are being made to introduce alternative energy sources, cleaner fuel, ship weight reduction, and the overall economic efficiency of ships. Therefore, using experimental data collected on aging bulk carriers, the paper explores the corrosion margin reduction potential considering its impact on hull weight. Assuming that the corrosive processes occur after four years of operation, a linear model that describes the percentage of plate wear as a function of the as build-in the thickness of inner bottom plates (IBP) of fuel oil tanks (FOT) located on the double bottom of aging bulk carriers, is analyzed. Over the course of 25 years, the IBP segment was monitored on 36 different ships surveys. In this way, 520 input data describing the depth of corrosion were formed. At the same time, records were kept on the mean thickness of the original metal plate, which enabled systematization of the empirical database and grouping of measured values by intervals of original plate thicknesses, and simple conversion of corrosion depth into adequate percentage values. Depth corrosion percentages were represented by standard linear models known in the literature. Based on this analysis, representative numerical and graphical results were obtained. Conclusions from the paper can assist to optimize corrosion margin and the energy efficiency of future vessels

Stalni nadzor srčanog izbačaja metodama Picco i Lidco prema Pak-u u septičnih bolesnika: kalibrirati ili ne ?

The accuracy of cardiac output measurement by two most widely used methods of less invasive hemodynamic monitoring and by the standard technique of thermodilution with pulmonary catheter was assessed. The measurements were carried out in septic surgical patients immediately after and between system calibrations. Study results showed satisfactory compatibility of measurements performed by the two methods and by pulmonary catheter in both phases, thus system calibration being recommendable in hemodynamically unstable septic patients.U ovom radu uspoređivala se točnost mjerenja srčanog izbačaja pomoću dviju najčešće upotrebljavanih metoda manje invazivnog hemodinamskog nadzora i standardnom tehnikom termodilucije plućnim kateterom. Mjerenje je provedeno kod septičnih kirurških bolesnika u razdoblju neposredno nakon i između kalibracija sustava. Rezultati su pokazali zadovoljavajuću podudarnost mjerenja u obje faze primjenom obiju metoda i pomoću plućnog katetera, pa se kalibriranje sustava preporuča u hemodinamski nestabilnih septičnih bolesnika

The Analyses of the Rate of Pitting Corrosion of a NiTi Rod in a Natural Marine Environment

The analysis of the behaviour of new materials in the natural environment is important for their application and commercial use. In order to explore the application of Shape Memory Alloys in the Maritime industry, this research focuses on the corrosive behaviour of the NiTi rod that was produced by means of a continuous casting process. The experiment included three samples of NiTi rods that were exposed to the marine environment for 6, 12 and 18 months at a depth of 3 metres below the surface. The morphological and chemical changes were analysed separately during the experiment. Ultrasonic thickness equipment and the Scanning Electron Microscope (SEM) technique were used for the tests that determined the corrosion rates and detected pitting. The changes in the chemical composition of the NiTi rod were investigated by means of an Energy Dispersive X-ray (EDX) analysis, in order to define the pitting behaviour of the rod`s surfaces during its exposure to seawater. The obtained research results prove that the rate of pitting corrosion follows a progressive curve – the minimum value of corrosion rate equalled 0.04 mm/month, while the maximum value was 0.12 mm/month

AN APPROACH TO THE PROBABILISTIC CORROSION RATE ESTIMATION MODEL FOR INNER BOTTOM PLATES OF BULK CARRIERS

This paper gives an approach to the probabilistic corrosion rate estimation model for inner bottom plates of bulk carriers. Firstly, by using the data from thickness measurements for inner bottom plates for considered 25 bulk carriers, the related best fitted linear model for the corrosion wastage is obtained as a function of ship’s age. In this model it is assumed that life of coating is 4 years. The obtained related corrosion rate is equal to mm/year. Notice that the obtained linear model is a particular case of a power model proposed in some earlier investigations. In view of the fact that the corrosion rate of ship hull structures is influenced by many factors, many of an uncertain nature, in recent studies several authors investigated a probabilistic model as more appropriate to describe the expected corrosion. Motivated by these investigations, and using 2926 thickness measurements for corrosion wastage of inner bottom plates of considered 38 special ships surveys, this paper examines the cumulative density function for the corrosion rate involved in the mentioned linear model, and considered here as a continuous random variable. The obtained statistical, numerical and graphical results show that the logistic distribution or normal distribution would be well appropriate for the probabilistic corrosion rate estimation model for inner bottom plates of bulk carriers. It is believed that this fact will be confirmed with greater statistical reliability in our future investigations including many more data collected on the considered corrosion

Function of the Stomatognathic System in Patients with Posttraumatic Stress Disorder

Svrha ovoga istraživanja bila je utvrditi zastupljenost temporomandibularnih disfunkcija (TMD) u veterana Domovinskoga rata koji boluju od posttraumatskog stresnog poremećaja (PTSP). Ispitivanu je skupinu činilo 100 ispitanika muškoga spola, sudionika rata s dijagnozom PTSP-a, a kontrolnu je skupinu činilo 94 ispitanika iste dobi i spola koji nisu sudjelovali u ratu i u kojih je psihijatrijskom dijagnostikom isključen PTSP. Istraživanje se sastojalo od anamnestičog i kliničkoga pregleda Anamnestičko ispitivanje provedeno je upitnikom u kojem su ispitanici odgovarali na postavljena pitanja izborom da−ne odgovora. Kliničkim je pregledom procijenjeno stanje čeljusnih zglobova (zvukovi, osjetljivost i bol prigodom palpacije čeljusnoga zgloba ) i žvačnih mišića (osjetljivost i bol prigodom palpacije žvačnih mišića), te je utvrđena funkcijska sposobnost stomatognatoga sustava (maksimalno otvaranje, maksimalna laterotruzijska kretnja u desno i lijevo, te maksimalna protruzija uz registraciju možebitne pojave boli ili zvuka). Statistički znatna razlika utvrđena je u gotovo svim mjerenim parametrima. Oboljeli od PTSP-a mnogo češće imaju subjektivne simptome i kliničke znakove TMD-a. 82% oboljelih od PTSP-a imalo je najmanje jedan simptom, a 98% najmanje jedan znak disfunkcija u usporedbi s 23,91% odnosno 50% ispitanika kontrolne skupine. Najčešći znak u objema skupinama bio je zvuk u temporomandibularnom zglobu (TMZ), i to u 64% ispitanika s PTSP om i 17,31% ispitanika kontrolne skupine. Statistički znatna razlika postoji i u granicama maksimalno mogućih kretnji jer ispitanici s PTSP-om znatno češće imaju ograničene kretnje otvaranja, desne i lijeve laterotruzije i protruzije. Najveće razlike među skupinama jesu u vezi s parametrima boli. 52% ispitanika s PTSP-om imalo je bolne TMZ-ove, a 91% imalo je bolnu najmanje jednu mšićnu lokaciju. Može se zaključiti da postoji povezanost između PTSP-a i TMD-a.The aim of this study was to determine the incidence of temporomandibular dysfunction (TMD) in veterans of the War for Independence, who suffer from posttraumatic stress disorder (PTSD. The examined group consisted of 100 male subjects with a diagnosis of PTSD, who had participated in the war, and a control group of 94 subjects of the same age and sex who had not participated in the war and in whom psychiatric diagnosis excluded PTSD. The study consisted of case history data and a medical examination. The examination included a questionnaire in which subjects answered questions with yes−no answers. During the medical examination the condition of the jaw joints (sounds, sensitivity and pain during palpation of the jaw joint) and mastication muscles (sensitivity and pain during palpation of the masticatory muscles) was assessed and the functional ability of the stomatognathic system determined (maximal opening, maximal laterotrusion movement left and right and maximal protrusion with registration of eventual occurrence of pain or sound). Statistically significant difference was determined in almost all measured parameters. The subjects with PTSD had subjective symptoms and clinical signs of temporomandibular disfunction (TMD) significantly more frequently. Eighty-two percent (82%) of those with PTSD had at least one symptom and 98% at least one sign of dysfunction, compared with 23.91% and 50% respectively of the subjects in the control group. The most frequent sign in both groups was sound in the temporomandibular joint (TMJ), which occurred in 64% of subjects with PTSD and 17.3% of subjects in the control group. Statistically significant difference was also found in the limitation of maximal possible movements, i.e. the subjects with PTSD had significantly more often restricted movements in opening, left and right laterality and protrusion. The greatest differences between the groups related to parameters of pain. Namely, 52% of subjects with PTSD had painful TMJ and 91% had at least one painful muscular location. It can be concluded that correlation exists between PTSD and TMJ