APPLICATION POSSIBILITIES OF THE S960 STEEL IN UNDERWATER WELDED STRUCTURES

In this paper, the application possibilities of the ultra-high strength (UHSS) Domex 960 steel in the underwater welded structures are analyzed. In the research, the investigated material has been tested in bead-on-plate wet welding conditions with the usage of different heat input values, namely 0.63 kJ/mm, 0.72 kJ/mm and 0.93 kJ/mm. Specimens were performed by the manual metal arc (MMA) welding method with the usage of rutile covered electrodes. Firstly, the nondestructive visual testing (VT) was carried out. In the next step, the metallographic macro- and microscopic tests were performed. Finally, the hardness of the weld metal and heat-affected zone (HAZ) was measured by the Vickers HV10 method. The performed experiments allow the statement that the Domex 960 steel could be welded in a water environment. It also showed that increasing heat input leads to decreasing the hardness in HAZ by 30 HV10. It may result in decreasing the susceptibility to cold cracking during butt- and filet welding in the water environment

Rotating systems misalignment identification using fuzzy clustering method

In the phase of operation, a technical system accomplishes goals which were the reason of the system designing and creation. The execution of operation tasks by the system causes changes in the system state. The changes in the dynamic state of rotating systems can be early identified by means of vibrations measurement. Therefore, the operational tests were performed in order to register time histories of vibrations. Next, characteristics of the collected vibration signals were recorded and the most significant of them were taken as an input for further studies. The studies were performed to formulate a method of identifying the rotating systems misalignment with high reliability. The method consists in fuzzy clustering implementation. According to the method the input signals were used to formulate the fuzzy clusters of the ability and inability states of the system. Thanks to the method, it is possible to identify the operation position of the system on base of the vibration signals analysis. In the paper the proposed method was described. The results of the method application for a gas turbine engine as an example of a rotating system are also presented. It should be emphasized that the reliability of the described operation state identification is higher than other methods implemented by the authors previously

PRELIMINARY STUDIES OF SEAMLESS FLUX CORED WIRES STORED IN EXTREME CONDITIONS

In the paper preliminary experimental studies of flux cored wires moisturized under controlled conditions are described. Three seamless wires of different grades have been placed in environmental chamber and moisturized in extremely adverse conditions (temperature T = 60° C, relative humidity H = 90%) for 240 hours. During this time measurements of weight gain and observations of surface of wires have been carried out. Also diffusible hydrogen amount in deposited metal has been determined by mercury method for one of moisturized wire. Significant increase of hydrogen level was observed (from H5 to H10 level). Further research will be aimed on determination of the effect of storage conditions on hydrogenation of deposited metal and quality of flux cored wires

Demographic characteristics of children with early clinical manifestation of inflammatory bowel disease

Abstract Introduction: Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), is a chronic condition of the colon and small intestine. The disease is common in young people (children and young adults), but it is rare in children younger than five years of age. Therefore, IBD developing during the first years of life (under the age of 5) is known as an early-onset IBD (EO-IBD), and it is considered to be a specific entity with a distinct phenotype. However, the available data on that issue are still insufficient. Aim: To determine the characteristics and clinical course of children with early-onset IBD. Material and methods: We performed a retrospective database analysis of 47 infants younger than 5 years old diagnosed with IBD. Patient's demographic data, including age, sex, and age at disease onset, were collected in 6 paediatric hospitals in Poland. Disease location was established on the basis of the review of all endoscopic, colonoscopic, histopathological, and radiological records. All possible complications were reported, as well as any treatment and its efficacy. Since the diagnosis was established all patients have been on follow up. Results: Among 47 children registered in the database, 23 (49%) had a diagnosis of CD, 16 (34%) had UC, and 8 (17%) had IC (indeterminate colitis). The mean age at diagnosis was 28.5 ±27.5 months; 57.4% were male. The most common location/type of disease was ileocolonic disease (L3). The most common complication of IBD was anaemia, found in 30 (63.8%) children. The observed course of the disease was either severe or moderate. In 4 children younger than 2 years old, surgery was performed. Conclusions: Inflammatory bowel disease in children younger than 5 years old includes UC, CD, and a relatively high proportion of IC. In early-onset IBD severe and moderate course of the disease is usually observed. Disease manifestation in these patients is predominantly ileocolonic

Mechanical and structural investigations of wings of selected insect species

This paper presents research and measurements leading to obtaining the Young’s modulus of wing bearing structures of selected insect species. A small testing machine intended for three-point bending and equipped with instruments registering low forces was constructed for the needs of the experiment. The machine was used to perform numerous bending tests of wings of three species of insects (obtained from a breeding farm): Attacus atlas, Vespa crabro, Libellula Depressa at various air-humidity conditions. Values of the force and displacement obtained in the course of the tests were used to calculate Young’s modulus. In order to do so, it was also necessary to obtain the moment of inertia of the wing cross-section. These values were measured on the basis of the images obtained with a SEM microscope. Obtained results were averaged and presented with a breakdown by air-humidity conditions. It was observed that Young’s modulus decreased with an increase of humidity, hence the calculations of the percentage decrease of this mechanical parameter were performed. Obtained results were compared with the observed structure which was also presented under light microscope. It transpired that the construction of a wing does not only influence the mechanical values but also it influences their susceptibility to the changes occurring in the environment. Thereby, differences between Lepidoptera and Hymenoptera insects were indicated also within the aspect discussed in this paper

Method for initial assessment of unit costs of public city transport means operation

The study deals with the problems connected with modeling and simulation of technical objects operation processes carried out within a certain class of complex technical systems. The analyzed system is a city bus transport system. The study presents a method for assessment of unit costs involved in a technical object’s being in selected operational states. One of the subsets of data to be used for modeling the process of a technical object operational state changes, includes data concerning the costs borne by the system when the object is in the analyzed operational states. In order to determine this data, it is often necessary to modify the system of costs registration used in a given operation system. Since it is a very expensive and log process, a method of initial assessment of indispensable data has been proposed, on the basis of a costs registration method and simulation of the operation process. The study also includes basic assumptions of the operation process model, being an important element of the developed method. The assumptions of the operation model have been formulated on the basis of identification of a real operation system of city bus transport system and experimental tests carried out in system

Method for initial assessment of unit costs of public city transport means operation

The study deals with the problems connected with modeling and simulation of technical objects operation processes carried out within a certain class of complex technical systems. The analyzed system is a city bus transport system. The study presents a method for assessment of unit costs involved in a technical object’s being in selected operational states. One of the subsets of data to be used for modeling the process of a technical object operational state changes, includes data concerning the costs borne by the system when the object is in the analyzed operational states. In order to determine this data, it is often necessary to modify the system of costs registration used in a given operation system. Since it is a very expensive and log process, a method of initial assessment of indispensable data has been proposed, on the basis of a costs registration method and simulation of the operation process. The study also includes basic assumptions of the operation process model, being an important element of the developed method. The assumptions of the operation model have been formulated on the basis of identification of a real operation system of city bus transport system and experimental tests carried out in system

Method of Building a Model of Operational Changes for the Marine Combustion Engine Describing the Impact of the Damages of This Engine on the Characteristics of Its Operation Process

This article deals with the modeling of the processes of operating both marine main and auxiliary engines. The paper presents a model of changes in operating conditions of ship’s internal combustion engine. The semi-Markov decision process was used to mathematically describe the process model of the engine. The developed model describes the effect of engine damage on the characteristics of its operation. A change in the input parameters of the model can simulate the influence of internal and external factors on the course of the analyzed process. A simplified calculation example is also presented for illustration purposes. The presented method together with developed algorithms and IT tools can be used to solve a wide range of problems related to the operation of marine main engines and other marine equipment as well as maritime and port facilities. This concerns primarily the economic, risk management and operational security issues of complex technical systems, as well as the readiness and reliability analysis of technical facilities

Fuzzy Identification of The Reliability State of The Mine Detecting Ship Propulsion System

The study presents the evaluation and comparative analysis of engine shaft line performance in maritime transport ships of the same type. During its operation, a technical system performs functions for which it was designed. It goes through different states. Dynamic state changes of a rotational system can be identified by means of its vibration measurement. For this purpose, a research was carried out which involved recording vibrations of the analysed rotational systems. The recordings were used for calculating selected characteristics in the time-domain, where one of the most unique is the value of the normalized mutual correlation function. On the basis of the concentration values, the characteristics which unambiguously determine the ability state were selected for further studies. Then an identification method for rotational system non-coaxiality was proposed. The method involves using fuzzy clustering. According to this method the values of input signal characteristics were used to formulate fuzzy clusters of system ability and inability states. The method can be used for identifying the current state of the system. The study presents the results of the application of this method in engine turbine shaft lines of minesweepers, with the rotational system selected as an example. It needs to be noted that the efficiency of identifying the operating state of the system with this method is higher than with other methods described in the literature by authors who deal with this issue. The research results have a significant impact on the evaluation of mechanical properties of the studied objects and directly affect operational states of mechanical systems, including those installed in minesweepers, thus determining their reliability

A Method for Determining the Usability Potential of Ship Steam Boilers

Ship large-power steam boiler may serve as an example of complex critical technical system. A basis for rational control of operation of such system is knowledge on its capability of fulfilling the tasks to which it was intended. In order to make it possible to apply computer aiding to operational decision-making the capability should be described analytically. In this paper it was proposed to express the capability of ship steam boiler ( considered a complex system) to perform service tasks, by calculating components of its usability potential in a given instant t. To this end , was distinguished a set of steam boiler fundamental features which formulate space of its technical states. Values and characteristic intervals of the features were defined and this way sub-spaces of serviceability and non-serviceability states of the object in question were determined. Next, in the considered space, technical state of the boiler and its usability potential was determined. Owing to this it become possible to quantitatively express the steam boiler functioning capability which served as a basis for elaborating an algorithm for controlling the operational processes of a complex technical system under action. In this paper is also described a way of application of the presented method to calculation of ship steam boiler usability potential, which may be especially instrumental in the case of operational control of the boilers of the kind , equipped with interstage reheaters, i.e. those operating with high values of operational parameters