Turbocharger turbine blades suffer from periodic vibration and flow induced excitation. The blade vibration signal is a typical non-stationary and sometimes nonlinear signal that is often encountered in turbomachinery research and development. An example of such signal is the pulsating pressure and strain signals measured during engine ramp to find the maximum resonance strain or during engine transient mode in applications. As the pulsation signals can come from different disturbance sources, detecting the weak useful signals under a noise background can be difficult. For this type of signals, a novel method based on optimal parameters of Ensemble Empirical Mode Decomposition (EEMD) and Teager Energy Operator (TEO) is proposed. First, an optimization method was designed for adaptive determining appropriate EEMD parameters for the measured vibration signal, so that the significant feature components can be extracted from the pulsating signals. Then Correlation Kurtosis (CK) is employed to select the sensitive Intrinsic Mode Functions (IMFs). In the end, TEO algorithm is applied to the selected sensitive IMF to identify the characteristic frequencies. A case of measured sound signal and strain signal from a turbocharger turbine blade was studied to demonstrate the capabilities of the proposed method.
A. Brandowski, Hoang Nguyen and Wojciech Frąckowiak
The neural network tuning procedure applied to reliability analyses of anthrop technical systems, based on judgements of experts - experienced operating practicians. Numerical and linguistic elicitation of the judgements, analyses of the network input and output data correlation and of the AHP method processing deviation are presented. Example of data elicitation and correlation analysis of a reliability arrangement of the seagoing ship propulsion system are included to the article.
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K undu S., K hare D., M ondal A. 2016. Future changes in rainfall, temperature and reference evapotranspiration in the central India
Michał Pająk, Łukasz Muślewski, Bogdan Landowski and Andrzej Grządziela
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.
Modern solutions used in compression-ignition internal combustion engines are quite similar to each other. The use of high-pressure, direct fuel injection results in high combustion rates with controlled exhaust emissions. One of the combustion system quality criteria is to obtain adequately high thermodynamic indicators of the combustion process, which are obtained through, among others, the right combustion chamber geometry. Its shape influences the fuel atomization process, turbulence of fuel dose, evaporation and the combustion process. Optimizing the combustion chamber shape is one of the decisive factors proving the correct execution of the combustion process. This article presents the methodology of choosing the combustion chamber shape (changes of three selected combustion chamber dimensions) by using the optimization methods. Generating multidimensional data while maintaining the correlation structure was performed by using the Latin hypercube method. Chamber optimization was carried out by using the Nelder-Mead method. The combustion chamber shape was optimized for three engine load values (determined by the average indicated pressure) at selected engine operating conditions. The presented method of engine combustion chamber optimization can be used in low and high speed diesel propulsion engines (especially in maritime transport applications).
Olgun Konur, Murat Bayraktar, Murat Pamik, Barış Kuleyin and Mustafa Nuran
The Turkish Merchant Shipping Industry has recently witnessed an increasing awareness of the importance to minimize environmental pollution and fuel oil consumption. Together with certain non-governmental organizations and media concerns about environmental protection, the International Maritime Organization (IMO) has been strict on controlling undesirable effects on the environment and, consequently, forcing shipping companies to minimize their emissions. Besides, today’s highly advanced technology companies over the world have developed various innovative systems that can be utilized to minimize carbon emission, thus giving assurance to relevant investors that their investments are most likely to turn out well with a considerable financial gain in the short or long term. Despite all such favorable developments, in a general look, shipping companies seem reluctant in making use of technologies providing efficiency in energy consumption. This reluctance has eventually brought about the term “Energy Efficiency Gap”. This research conducts a questionnaire, created by Acciaro et al. , among the shipping companies in Turkey. 20 respondent companies, who represent 26 percent of the Turkish owned merchant marine fleet of over 1000 gross tonnage in terms of deadweight cargo capacity, participated in the research. The Pearson correlation analysis was used, and interpretations were made according to the obtained statistical values. The aim of the research was to identify reasons and points restraining the use of new technologies regarding energy efficiency, as well as to develop proposals for the innovators in this field about how to overcome this handicap concerning technical and managerial aspects of gaining energy efficiency.
Terrain database is the reference basic for autonomous underwater vehicle (AUV) to implement underwater terrain navigation (UTN) functions, and is the important part of building topographical features model for UTN. To investigate the feasibility and correlation of a variety of terrain parameters as terrain navigation information metrics, this paper described and analyzed the underwater terrain features and topography parameters calculation method. Proposing a comprehensive evaluation method for terrain navigation information, and constructing an underwater navigation information analysis model, which is associated with topographic features. Simulation results show that the underwater terrain features, are associated with UTN information directly or indirectly, also affect the terrain matching capture probability and the positioning accuracy directly.
Jianhua Zhang, Won-Hee Kang, Chunwei Zhang and Ke Sun
Typical tripod foundations are designed using deterministic computational models according to relevant standards and codes. However, for more cost-safety balanced design, uncertainties in significant parameters should be considered in preliminary design to ensure meeting a specific probabilistic safety target in the context of the complex configuration of a tripod structure. In this article, uncertainties associated with design parameters and modelling errors are considered using Monte Carlo simulations, in order to determine the key structural design parameters, and to determine the optimal balance between design parameters and design requirements. A Spearman rank-order correlation based analysis is carried out to understand the effects of design variables on maximum deformation, total weight, and natural frequency, and to have insight about important design parameters for improvement of a preliminary design. It is found that the tower diameter has the most significant effect on the maximum displacement on the hub as validated through engineering case studies. In addition, a statistical framework, which identifies influential design parameters and provides reliability evaluation, is proposed for the structural design of a tripod OWT system. The design cases considered in this study indicate that a simple deterministic design check cannot guarantee the required reliability level of the structure, and the cost-safety balance can be achieved by a reliability analysis with the consideration of the uncertainties in the structure.
Dumitru Mihăilă, Andrei-Emil Briciu and Gina Ursul
The daily, monthly and annual variations of the tropospheric ozone in the area of Suceava municipality are described and explained by using the correlations between the ozone concentration and the local meteorological parameters. The meteorological parameters are as follows: the air temperature, the air humidity, the sunshine duration, the wind speed and direction. All parameters represent hourly datasets recorded in the interval 2004-2007. The Pearson correlation coefficients and the linear regressions were obtained for daily, monthly and yearly scales. Significant positive correlations between the O3 and the temperature and strong negative correlations between the O3 and the air humidity were found, especially between 11 a.m. and 8 p.m., during the warm season. The sunshine duration and the wind speed and direction were found to have weaker, but good positive correlation with the O3 during the same hourly interval. The weekend effect of the ozone exists in the City of Suceava too, as the reduced road traffic during the weekend causes higher concentrations of ozone. The wavelet analyses were conducted in order to further explain the variability of the ozone.
Anbazhagan S., Paramasivam C.R., (2016). Statistical Correlation between Land Surface Temperature (LST) and Vegetation Index (NDVI) using Multi-Temporal Landsat TM Data. Int. Journal of Advanced Earth Science and Engineering 2016, Vol. 5, pp. 333-346.
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