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Brociek W.,Warsaw University of Technology | Wilanowicz R.,Radom University of Technology
Przeglad Elektrotechniczny | Year: 2011

The paper presents a circuit model of three phase arc arrangement, taking into account the nonlinearity of the arc appearing In the particular phases as well as the windings vector groups of a furnace transformer. This model was designed on the ground of parameters, resulting from a voltage current characteristic of the arc. At modeling of changes of parameters of an arc we applied the random values of resistance. The values of higher harmonics of current and voltage for each considered case have been evaluated by using the simulation program MicroCap - 8. In the paper we have included the exemplary results of numerical calculations.

Religa P.,Radom University of Technology | Kowalik-Klimczak A.,Warsaw University of Technology | Gierycz P.,Warsaw University of Technology | Gierycz P.,Polish Academy of Sciences
Desalination | Year: 2013

Results of studies of the effects of concentrate salt solutions characterized by low pH, on the nanofiltration membrane surface properties used for the separation of chromium(III) have been presented in this paper. It was shown that the low pH of the concentrate salt solutions and cleaning bath with hydrochloric acid irreversibly altered the charge of tested membranes. As the consequence an instability of permeability and selectivity of the membrane during the process was noticed. The effect of alkaline bath used after cleaning with a solution of hydrochloric acid to regenerate the surface charge of tested membranes was also examined. The results showed that the use of bath in the form of sodium hydroxide leads to the partial recovery of a low surface charge of the membranes. In addition a significant improvement in the stability of the tested NF membranes used for the separation of chromium(III) from concentrate salt solutions at low pH was observed. Moreover, SEM images obtained for the tested membranes cleaned with solutions of HCl and NaOH indicated no mechanical defects in the structure of the examined membranes. © 2012 Elsevier B.V.

The paper presents the results of simulation of the power network composed of the main supplying point (PCC) of 15kV, 4km overhead supply line of middle voltage, filter of k th harmonics and 6- and 12-pulse rectifier. In each case we have determined the impedance characteristics of the network as the function of frequency in steady state of AC analysis. The values of the voltage harmonics corresponding to the circuit before and after filter of k th harmonic have been also calculated. The supplying line was simulated by a two-port of the distributed parameters. The numerical data used in experiments have been acquired from the real (physical) power system. All experiments have been performed using Micro-Cap 8 program. In the paper we have included the exemplary results of the numerical calculations.

Bakar M.,Radom University of Technology | Okulska-Bozek M.,Radom University of Technology | Zygmunt M.,Radom University of Technology
Materials Science | Year: 2011

We investigate the effect of polyimide and poly(amic acid) contents on the properties of epoxy resin. Charpy impact strength increases by 80% and 70% with the addition of 10 wt.% poly(amic acid) and 15 wt.% polyimide, respectively. However, the flexural strength is improved by 95% and 73% (as compared with the neat epoxy resin) by the addition of 5 wt.% polyimide and 5 wt.% poly(amic acid), respectively. Moreover, the addition of 10 wt.% polyimide resulted in a twofold increase in the impact adhesive strength, while the tensile adhesive strength of the epoxy increases by 70% with only 5 wt.% polyimide. The infrared spectra show that the obtained compositions containing polyimide or poly(amic acid) exhibit semiinterpenetrating polymer network structures characterized by a relatively high flexibility and very good mechanical properties. © 2011 Springer Science+Business Media, Inc.

Pajak M.,Radom University of Technology
Journal of Intelligent and Fuzzy Systems | Year: 2015

Quality of power units' maintenance schedule is one of the most important factors, which influences reliability and efficiency of power plant exploitation process. The schedule is created during a planning process taking into consideration a lot of different criteria. These criteria result from bidirectional connections between power plant exploitation system and surrounding systems. Therefore they are formulated in completely different domains. The criteria often are defined approximately. Frequently they are contradictory so it is not possible to fulfil all the criteria simultaneously. Because of all these difficulties, the creation process of coherent assessment system, comprising all considered criteria, is very complicated. Additionally, the number of maintenance schedule possible variants is very big. Therefore, to reach high quality of maintenance management, it is necessary to apply automatic system of power units maintenance schedules generation. This paper describes the implementation of artificial intelligence techniques in the area of maintenance management. The automatic system of power units maintenance schedules generation was created using genetic algorithms as optimization technique and developed fuzzy assessment system. In the paper, the industrial implementation of the system is also presented. © 2015 - IOS Press and the authors.

Komorska I.,Radom University of Technology
Solid State Phenomena | Year: 2012

The method of modelling the signal of vibrations of the internal combustion engine based on the discrete wavelet transform (DWT.) is presented in the paper. This method is suitable for the representation of transient processes, which occurs in the vibroacoustic signal (VA) generated by the engine. The model is identified on the basis of the vibration signal recorded when the car is driving at a constant speed. The base model and its measures are created for the new engine and the control measurements, performed either at the determined time periods or car mileage, are compared to them. This base model must be actualised after each engine overhaul and as its wear and tear progresses, due to changes of the vibration characteristics. On account of a random character of vibration responses the envelope of the modelled signal is utilised for diagnostic purposes. The model based diagnostic method was verified in the paper on the example of the engine exhaust valve defect. © (2012) Trans Tech Publications.

Religa P.,Radom University of Technology | Kowalik A.,Radom University of Technology | Gierycz P.,Radom University of Technology
Journal of Hazardous Materials | Year: 2011

The article presents results of investigation concerning an influence of tannery wastewater composition on chromium(III) concentration in the wastewaters during the nanofiltration process (NF). The effectiveness of this process strongly depends on mutual relation between chloride and sulfate ions concentration in tannery wastewater. For this reason, the optimum composition of the tannery wastewater should consist chloride/sulfate ions ratio close to 1. Moreover, an influence of transmembrane pressure (TMP) and the " ageing" of chromium tannery wastewater on the efficiency of the process has been investigated. Optimal range of TMP equal to 14-16. bar has been assumed for the process. It is necessary to point out that the optimum transmembrane pressure can be changed in the case of the membranes with different permeation properties. " Ageing" of the tannery wastewater reduces only a little an efficiency of the process. Experimental results demonstrated that the NF process could be successfully used for the concentration of chromium in the tannery wastewater with high permeate flux, selectivity and performance stability. © 2010 Elsevier B.V.

Bojarczak P.,Radom University of Technology
Insight: Non-Destructive Testing and Condition Monitoring | Year: 2013

Squat flaws, when left unsupervised, can pose a threat to the safety of railway traffic. Unfortunately, as surface flaws, they cannot be detected by traditional ultrasonic methods. The application of eddy current to their detection is extremely difficult in the conditions occurring on the railway track. It seems that vision-based techniques can be a good alternative solution. The paper presents an algorithm allowing for the detection of these flaws. It uses wavelet transform to extract the rail from the background of the image. A Gabor filter bank along with a support vector machine (SVM) as a classifier were used in the squat detection process. The optimal number of features used to discriminate between the squat and the area without squat was selected with the help of the sequential feature selection method. The overall classification rate for the system was 93%.

Religa P.,Radom University of Technology | Kowalik A.,Radom University of Technology | Gierycz P.,Radom University of Technology
Desalination | Year: 2011

This paper presents results concerning the influence of membrane properties on effective recirculation of chromium(III) from tannery wastewater by nanofiltration process. DK, HL, DL "thin film" membranes and asymmetric CK membrane were tested for theirs permeability and selectivity on model chromium solution contained 2gCr3+/dm3, 10gCl-/dm3 and 10gSO4 2-/dm3. Presented results allowed to conclude that both the high permeability and selectivity of NF membranes used for chromium recirculation from low pH, concentrate salt mixture solution are dependent on the membrane surface charge phenomenon. The retaining of the high permeate flux of chromium tannery wastewater at pH below 4, required the use of membranes with their IP as low as possible to assured the negative NF membrane surface charge and low chloride ions retention equal to 7-11%. As a consequence the polarization effect was reduced and the increase of permeate flux was observed. The use of such membranes guarantees obtaining of both a high permeate flux and a concentrated solution of chromium(III) as retentate which is suitable for recirculation. Due to the fouling and aggressive conditions characterized the tanning wastewater the polyamide/polysulfone membranes are suggested. The cellulose acetate membranes do not ensure satisfied results during treatment of tannery wastewater. © 2011 Elsevier B.V.

Bakar M.,Radom University of Technology | Kostrzewa M.,Radom University of Technology
Journal of Thermoplastic Composite Materials | Year: 2010

The present work investigates the mechanical properties of conventional and hybrid composites based on epoxy resin. Diglycidyl ether of bisphenol A was used as the matrix and triethylenetetramine was used as the curing agent. Polyurethane (PUR) used was based on polyether and toluene diisocyanate. Impact strength (IS), critical stress intensity factor (Kc), tensile strength (TS) and flexural strength were evaluated as function of modifiers content. It is shown that IS is increased by approximately 120% and 200% with the addition of respectively 10 phr of glass beads (GB) or 10 phr PUR, in comparison with IS of the unmodified epoxy resin. Moreover, Kc was increased by approximately 20% with 10 phr GB and 35% with 10 phr PUR. The addition of 15 phr PUR gave compositions with 30% enhanced TS and 40% increased tensile strain at break. However, the strain at break decreased with increasing amount of GB. Hybrid composition containing 10 phr PUR and 15 phr GB exhibited the maximum tensile energy to break corresponding to 80% and 85% improvement respectively in relation to the energy at break of the virgin epoxy resin and composition with only 10 phr PUR. Infrared spectra analysis of the compositions containing PUR revealed the formation of an interpenetrating polymer network structure between the modifier and the polymer matrix. © 2010 The Author(s).

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