Papers by Keyword: Energy

Abstract: The use of renewable (alternative) energy sources of energy is still a hot topic. In the electrical engineering laboratories of the Department of technical subjects created a model of micro energy sources that can be operated in various operating modes to simulate in various operating conditions. The machine set is dedicated for laboratory of electric engeneering. Goal is to show students in the subject Renewable energy sources and their application, practical use and parameters an the asynchronous generator. The article deals with the mechanical concept and mechanical construction of laboratory machine set.

Abstract: The article deals concept of measuring the electric motor-generator sets and represents the completion of a comprehensive design laboratory for electrical energy mikrozdroje laboratories. Given that the test set is powered energy industrial installations can not underestimate the risks arising from its operations. The seemingly simple design of the electrical part with manual control may seem a step back (in particular, from the viewpoint of universal, sometimes precipitous and unnecessary digitization anything), on the other hand the solution chosen allows combination possibilities that are not in the conventional digital control feasible.

Abstract: In this paper a study on the magnetostrictive-piezoelectric composite material with different configuration in a variety of external magnetic field changes was presented. An experimental setup for investigation of properties of magnetostrictive-piezoelectric materials was prepared. The hybrid structure was made of magnetostrictive composite (based on Terfenol-D) and piezoelectric materials. Experimental results shown the response of prepared hybrid material to the rate of magnetic field changes at the same direction of magnetic field vector. Based on the obtained results, it was found that the prepared composite material exhibits magneto-electric effect in the case of work in a variable magnetic field. This phenomenon could be used as a support for the tensiometers during measurements of deformation or cracks propagation of the samples during fatigue tests.

Abstract: Composite materials are a regular part of many industries - aerospace, automotive, mechanical engineering. Lower weight and comparable in some ways even better mechanical properties, are the reason why composites progressively substitute traditional metal based material. The article describes the design of composite tub with metal reinforcement. Compares the theoretical and real output of sample produced from CF prepreg specially designed for absorbing the energy during crash impact. The results show that the sample due to its deformation is able to absorb some energy and become a material usable in structural applications.

Abstract: This paper reports the results of measurements during hardening and drying of specimens made of alkali activated slag mortars. The aim of this paper is introduce the effect of curing method and time on the microstructure of alkali activated slag mortars. An understanding of microstructure−performance relationships is the key to true understanding of material behaviour. The results obtained in the laboratory are useful to understand the various stages of micro-cracking activity during the hardening process in quasi-brittle materials such as alkali activated slag mortars and extend them for field applications.

Abstract: The VZN shock absorber concept granted with European Patent EP 1 190 184 is characterized by damping coefficients self according with road and load conditions.The simulations made on vehicles equipped with new VZN shock absorbers concept relative to standard one, indicates better behavior concerning stability, comfort and reduced dissipated energy, with fuel consumption and pollution reducing effect.Starting on these remarks the paper evaluates the influence of the damping characteristic in suspension performances and dissipated energy, based a simulation on a Californian road realized with Matlab Simulink software.Since year 2006 simulations on model ¼ cars demonstrates the VZN damper concept give skyhook behavior, decrease squat, vertical acceleration, the number and intensity of stopper bumper collision, the adherence, increasing thus the vehicle stability, comfort and reliability.Tests on models ½ car, show the VZN concept increases stability at pitch and roll and confirm the previous results obtained on ¼ models.The current work completed previous research with one demonstrating other VZN qualities e.g. its capacity to manage damping coefficient, no more and no less, assuring high performances and thus reducing the dissipated energy, with favorable effect for reducing fuel consumption and pollution.The comparison between the behaviors of the VZN shock absorber relative to the standard shock absorber has been realized for body displacement, squat, acceleration and dissipated energy.The VZN progressive damper concept gives better behavior comparative to standard one, 6% at car body bounce, 37 % for RMS acceleration and 28.4 % for dissipated energy, these means it confer better body-ground clearance, comfort and fuel consumption and pollution.The VZN damping coefficients accorded with the vehicles load and with road unevenness confer a soft response at low excitation and strong reactions at high excitations, dissipating energy function of the needs, assuring thus comfort at small and medium excitation and protecting the axles and body at hard conditions.

Abstract: Oral adjusting of ceramic prostheses involving abrasive machining using dental high-speed rotary cutting instruments is a central process in restorative dentistry, because this process affects not only restorative quality but also patients’ comfort. However, the dental grinding process, especially dental grinding of high-strength ceramic prostheses, is less understood in clinical dentistry. This paper presents dental grinding of an innovative high-strength lithium disilicate ceramic in in vitro oral adjusting regime using a dental high-speed electric handpiece and diamond burs. The dental abrasive machining characteristics were quantitatively evaluated in terms of normal and tangential forces, force ratio, and specific grinding energy as functions of clinically relevant dental grinding variables including depth of cut and feed rate and feed direction of burs. The results showed that the dental tangential and normal forces and specific grinding energy exhibited significant dependences on depth of cut, feed rate and direction of burs, but revealed significantly small scales compared to engineering machining regime. Clinical implication was given that down grinding undoubtedly reduced the abrasive adjusting forces to relieve patients’ discomfort in oral regime. Moreover, dentists must be cautious in dental abrasive adjusting of the lithium disilicate ceramic prostheses at or beyond the specific material removal rate of 2.4 mm³/min due to significantly large forces and vibrations.

Abstract: One between fundamental problems of mechanical engineering are accordingly to available energy from nature after an adequate modification at a certain point where is using to generate a practical operation. Sonique theory establish by romanian scientist George Constantinescu is one of the method who permit this operation. This paper is demonstrating possibility for using mechanical power-transmission through sonique and ultrasonique waves in heating systems, in economic advantages conditions. Applications of this theory is to generate heat with sonique and ultrasonique waves, and pass over (send forward) through cold pipes, and heating only sonique resistance at wished place

Abstract: Energy consumption of buildings is increasing steadily and occupying approximately 30-40% of total energy use. It is important to predict heating and cooling loads of a building in the initial stage of design to find out optimal solutions among various design options, as well as in the operating stage after the building has been completed for energy efficient operation. In this paper, an artificial neural network model has been developed to predict heating and cooling loads of a building based on simulation data for building energy performance. The input variables include relative compactness, surface area, wall area, roof area, overall height, orientation, glazing area, and glazing area distribution of a building, and the output variables include heating load (HL) and cooling load (CL) of the building. The simulation data used for training are the data published in the literature for various 768 residential buildings. ANNs have a merit in estimating output values for given input values satisfactorily, but it has a limitation in acquiring the effects of input variables individually. In order to analyze the effects of the variables, we used a method for design of experiment and conducted ANOVA analysis. The sensitivities of individual variables have been investigated and the most energy efficient solution has been estimated under given conditions. Discussions are included in the paper regarding the variables affecting heating load and cooling load significantly and the effects on heating and cooling loads of residential buildings.

Abstract: This paper proposes the correlation of absorbed energy with calculated energy using the power spectrum density (PSD) method. The total absorbed energy was obtained using the dial/encoder system may significantly vary depending on the strength and ductility of the material. In addition, according to ASTM E23, over 80% of absorbed energy is inaccurate and approximate. For this reason, we determined the energy collected from the dial/encoder Charpy impact test using the signal processing approach. Strain gauges were connected to the Charpy impact striker and the high frequency data acquisition system in order to capture the dynamic impact strain response. Specimens of an aluminium alloy of 6061-T6 and carbon steel 1050 with different velocities and thicknesses were used in the experiment. The specimens are prepared based on the ASTM E23. A collection of signal was converted from the time domain to the frequency domain by means of PSD method and the area under its plot was used to calculate strain energy. The comparison between energy absorbed during the experiment with PSD peak and the strain energy were performed using different materials, velocities and thicknesses. The total energy absorbed for both material with the PSD peak and the strain energy using the dial/encoder system can be linked by a power law equation with R² 96% and R² 94 %. Thus, the effects of the strain signal pattern and impact duration with different parameters were correlated with the PSD peak and the strain energy. This correlation using PSD can be used as an alternative for the charpy impact test and solve the problem of inaccurate absorbed energy.