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Reducing Pollution Levels Generated by Short Sea Shipping. Use of Bayesian Networks to Analyse the Utilization of Liquefied Natural Gas as an Alternative Fuel

ports in the process of SOx emission reduction , Maritime Studies, Vol. 12, No. 10, 2013. [13] Heckerman, D., A tutorial on learning with Bayesian networks. Innovations in Bayesian networks, (pp. 33-82), Springer Berlin Heidelberg, 2008. [14] Kegalj, I., Traven, L., Influence of Cargo flows on Sustainable Development of East Mediterranean “Motorways of the sea” , Journal of Maritime & Transportation Sciences, Vol. 53, No. 1, pp. 19-33, 2017. [15] Laskey, K. B., Sensitivity analysis for probability assessments in Bayesian networks , In Proceedings

Open access
Exact Solution of the Harmonic Problem for a Rectangular Plate in Flat Deformation by the Method of Initial Functions

Abstract

A wide range of applications is based nowadays on analytical developments which allow a precise and effective approach and short time of computations compared with the time required for numerical methods; in this way these developments are suitable for calculations in real time. This work proposes an approach for solving a two-dimensional harmonic problem of a rectangular plate under local surface loading using Vlasov’s symbolic method of initial functions and a general solution of the harmonic equation for a rectangle. Substituting the harmonic functions in symbolic form for the corresponding solutions allows us to give the exact solution of the problem in trigonometric form.

Open access
Development and Examination of a Knee Prosthesis Geometry

Abstract

The necessity for the knee prosthesis is confirmed by the large increase in the number of patients suffering from arthrosis, which is a present-day disease. Despite this need, there doesn’t exist an optimal knee prosthesis. Nowadays the development of the knee prostheses is progressing. It is very difficult to define the required geometry with traditional methods, because the movement conditions to be created by the prostheses should be similar to the movements of the human knee. During previous research the biomechanical research team of the Szent István University occupied with experimental measurements of the healthy human knee joint movement. In this paper I would like to introduce a method of prosthesis geometry development. As a result, a knee prosthesis geometry has been created which is approaching the movement form of the real human knee joint.

Open access
Durability Tests of Ball Valve Prototype with Flowmeter Operation

Abstract

The results of the investigation of the prototypical ball valve are presented in this article. The innovation of the tested valve is a ball with a built-in measuring orifice. The valve has been subjected to durability tests. Leakage under three temperatures: ambient, -30°C and +100°C was analyzed. Sealing elements of the valve were tested for roughness and deviation of shape before and after the cycles of operation. Ball valve operation means cycles of open/close. It was planned to perform 1000 cycles at each temperature condition accordingly. Tests of the valve were performed under gas pressure equal to 10 MPa. The research was carried out under the Operational Program “Intelligent Development” (POIR 01.01.01-00-0013 / 15 “Development of devices for measurement of media flow on industrial trunk-lines”.

Open access
Electromagnetic Launcher Aviation Gun of the Future

Abstract

The electromagnetic rail launcher is a type of high-energy weapon that uses a strong magnetic field to project missiles. To create this field, a current pulse source is needed to provide sufficiently high voltages and currents. The study thoroughly examines the principle of electromagnetic operation of the rail launcher, with particular emphasis on how to achieve the highest electromagnetic field strength. The analysis has been subjected to the source of the impulse current and the tendency of their development in the near future. The subject of the appropriate rails selection and their mutual arrangement has been touched up to attain adequate strength against the harmful effects associated with the flow of high currents. Considerations have been taken to protect the rails from the harmful effects of large-scale current flows, and the topic of the projectile itself to the electromagnetic field was raised. The rapid development of technology over the last few years indicates that high-energy weapons will be the basic weapon of all types of forces in the near future. The development of electromagnetic railroads requires the solution of many mechanical problems and harmful phenomena.

Open access
Influence of Thermal Signal Characteristics on Defect Detection in GFRP by Active Optical Thermography

Abstract

Advances in technological development, since the 1990s, has been associated with the development of two basic domains of knowledge: information technology and material engineering. The development of material engineering is directly related to composite materials. One group of composite materials are fibre-reinforced composites. Due to their unique properties, they are used in various fields of engineering sectors. Composites reinforced with glass fibre (GFRP) are the second most commonly used composite after carbon fibre reinforced composites (CFRP). GFRP in many cases can replace traditional structural materials, which are usually made from metal. Of course, this material is exposed to damage both in production and operation phases. One method of non-destructive testing that effectively identifies defects in GFRP is active optical thermography. In this method, for thermal stimulation of the tested material, various types of heat sources are used for example: heating lamps, lasers etc. This article analyses the influence of the characteristics of the thermal optical sources on detection of typical defects in GFRP.

Open access
Laminar Burning Velocity Predictions of Single-Fuel Mixtures of C1-C7 Normal Hydrocarbon and Air

Abstract

The numerical modelling of combustion phenomena is an important task due to safety issues and development and optimization of engines. Laminar burning velocity (LBV) is one of the most important physical properties of a flammable mixture. Knowing its exact value if crucial for assessment of flame stabilization, turbulent flame structure. It influences strongly safety, probability of knocking combustion and it is one of parameters used for assessment and development of detailed chemical kinetic mechanisms. Hence, the goal of this work is to develop models by means of Machine Learning algorithms for predicting laminar burning velocities of single-fuel C1-C7 normal hydrocarbon and air mixtures. Development of the models is based on a large experimental data set collected from literature. In total more than 1000, LBVs were accumulated for hydrocarbons from methane up to n-heptane. The models are developed in MATLAB 2018a with use of Machine Learning toolbox. Algorithms taken into account are multivariate regression, support vector machine, and artificial neural network. Performance of the models is compared with most widely used detailed chemical kinetics mechanisms’ predictions obtained with use of LOFEsoft. These kind of models might be efficiently used in CFD combustion models based on flamelet approach. The main advantage in comparison to chemical kinetics calculation is much shorter computational time needed for computations of a single value and comparable performance in terms of R2 (coefficient of determination), RMSE (root-mean-square error) and MAE (mean absolute error).

Open access
Experimental Verification of the Use of Dummies for Tests in Empirical Research

Abstract

The issues related to the use of test dummies for experimental research in the field of automotive engineering have been addressed. The article discusses the historical introduction and development of the dummies in the biomechanical tests, which have contributed to the replacement of, previously conducted tests on corpses or volunteers. The evolution of dummies development Evolution of the dummies construction development to the present times has been presented. Question was raised: what is the “similarity” between the dummy living human being. Contemporary dummies reflect very well features of the human body are made of good quality materials and can be equipped with numerous sensors performing various measurements. Comparative empirical tests carried out with an adult dummy and a living adult of similar parameters such as: size (weight and height) body proportions have been presented. The impact of vibrations on the human occupant riding a motor vehicle was examined, with road tests being carried out of realized driving on various road surfaces within that work and with the data recorded being analysed in the time domain and frequency domain. In the time domain, time histories of the accelerations recorded were analysed and the root-mean-square (RMS) acceleration values were calculated. In the frequency domain, the power spectral density (PSD) values and the absolute transmittance (amplification) values were determined for the acceleration signals recorded. The analysis of the measurement results for the ability to absorb vibration by living human being and the dummy has been done. The differences and similarities between the living human subject and the test dummy have been presented from the point of view of utilizing such subjects for experimental tests.

Open access
Wind Power Plants – Types, Design and Operation Principles

Abstract

Many countries worldwide support green energy production on large scale mostly by solar or wind energy subsidizing manufacture and operation of such systems. During the last two decades, there has been significant increase in wind energy production globally. Statistics show continuously growing investments in the development and installation of wind turbines and farms. Currently, wind energy is the second most important source of renewable energy after water energy. By 2016 global cumulative installed wind capacity surpassed 432 k MW [GWEC]. In last several years, most dynamic growth in wind power generation investments was recorded in Asia. Europe, in comparison, has less impressive but steady growth in wind power plants through the years. In this article, authors present global demand on energy in comparison to efficiency of wind power plants in relation to the local and global location as well as to the scale of installed system. Authors also present statistical data concerning wind power plants development. General classification, using number of criteria (ex. power output, construction size, rotor axis orientation and other) of wind to electric power converting devices is presented. Various types of devices, which authors describe in this article, can perform conversion of wind blow energy to the electric energy using different yet similar methods.

Open access
The Methods of Quality Assessment of the Tracked Suspensions of the Combat Vehicles

Abstract

The extortions that result in the vibrations of a hull of the combat vehicle have an impact on the tracked combat vehicle during the off-road driving. They may have a negative impact on the crew, internal equipment, shooting accuracy. A level of the hull loads depends on quality of the suspension system, which main responsibility consists in minimising an amplitude of the vibrations. Therefore, it is necessary both to improve a structure of the suspension system, and its components, as well as their optimisation.

The tests of the driving smoothness of the vehicle and quality of the suspension elements can be realised both within a frame of the model tests and while driving in the real conditions. The assessment criteria of the driving smoothness are directly related to the negative influence of the vibrations to the human body. The suspension quality should be assumed both upon an execution of the vehicle prototype, and during the design or modernisation phase. It results both in reducing the time, and minimisation of the costs and risk related to the structure development. The model tests enable to evaluate the driving smoothness and comfort prior to an execution of the prototype. The tests on the test tracks in the final phase of the development are carried out in order to evaluate the driving smoothness.

Open access