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The study presents the results of research on the process of geraniol (GA) transformation in the presence of natural minerals: montmorillonite, mironekuton, halloysite and also in the presence of halloysite modified with 0.1 M water solution of H2SO4. To obtain information on the structure of the used catalysts, instrumental studies were performed (SEM, XRD, FT-IR, XRF, BET). The second part of the research consisted in examining the influence of individual parameters (temperature, catalyst content, and reaction time) on the course of GA transformation process. The syntheses were carried out without the application of solvent and under atmospheric pressure. To determine the most beneficial process conditions, two functions were selected: GA conversion and selectivity of GA. The proposed method of GA transformation on such minerals: montmorillonite, mironekuton, halloysite, has not been described in the literature so far.

This paper introduces optimization of machining parameters for high-pressure abrasive water jet cutting of Hardox 500 steel utilizing desirability function analysis (DFA). The tests were carried out according to the orthogonal matrix (Taguchi) L9. The control parameters of the process such as pressure, abrasive flow rate, and traverse speed was optimized under multi-response conditions namely cutting depth and surface roughness. The optimal set of control parameters was established on the basis of the composite desirability value obtained from desirability function analysis and the significance of these parameters was determined by analysis of variance (ANOVA). The effects show that optimal sets for high cutting depth and small surface roughness is high pressure, middle abrasive flow rate, and small traverse speed. A confirmation test was also leaded to validate the test results. Results of the research have shown that machining efficiency at keeping good level quality of cut surface can be improved this approach.

This paper presents the modeling of the geraniol transformation process using response surface methodology (RSM). It uses a combination of both statistical and mathematical modeling methods to study the relationships occurring between several explanatory variables and one or more response variables. Interactions occurring between process variables are studied using statistical techniques. In this paper, the influence of the most important process parameters, such as temperature 20–110 °C, catalyst concentration (mironecuton) 1.0–5.0 (wt.%), and reaction time 0.25–2 (h), is presented. The response functions were the conversion of geraniol (GA), the selectivity of conversion to thumbergol (TH), and the selectivity of conversion to 6,11-dimethyl-2,6,10-dodecatriene-1-ol (DMC). In addition, the effects of all control parameters on each of the response parameters were presented in the form of second-order polynomials. Attempts were made to identify process conditions that would allow high values of the process function.

Composites are materials with a heterogeneous structure, composed of two or more components with different properties. The properties of composites are never the sum or average of the properties of their components. There is a lot of research and many models on the different property assessments of composite materials. Composites are used as construction materials in key areas of technology, including in civil and mechanical engineering, aviation and space technology, and others. This work presents a modern composite material created with 3D-printing technology using the SLM method, and the possibility of its processing with one of the advanced manufacturing technologies, i.e., the Abrasive Water Jet (AWJ). Tests planned using DoE methods were carried out by changing control parameters such as the pressure, abrasive flow, and traverse speed. As a dependent parameter, the surface roughness parameter Sq (squared mean height) was selected and measured in different places of the cut composite. Based on the S/N ratio, the most favorable control parameters of the cutting process were also determined to achieve the lowest roughness of the cut surface. A clear effect of the controlled cutting process on the surface roughness was observed, as well as roughness variation for the metal and polymer component. In addition, the contact surface of the polymer with the metal in the cut zone was analyzed. Analysis of the contact surfaces on the microscope showed that the gap between the polymer–metal contact surfaces does not exceed 2.5 μm.

High-pressure water jet machining is characterized by wide possibilities of cutting diverse materials together with multi-layer materials with dissimilar properties, accurate cutting complex profiles, as well as conducting them in uncommon conditions, especially in cases of thick materials. An additional advantage of water jet technology is its environmental friendliness. This paper presents tests of the cutting performance of tool steel with the use of an abrasive water jet (AWJ). The state-of-the-art has shown insufficient scientific evidence in AWJ tool steels cutting using recycled abrasive materials. Therefore, the main motivation for this paper was to carry out research from an environment aspect. The reuse of abrasives and the use of recycled materials have immense potential to reduce processing costs while remaining environmentally friendly. The RSM method was used for modeling and optimization. A response surface design (RSM) is a package of an advanced design-of-experiment (DOE) approaches that support better understanding and optimize response, exploring the relationships between several explanatory variables and one or more response variables. Based on this research, feed rate is the key factor influencing the depth of cut, while the water nozzle diameter has a secondary effect, and the concentration of abrasive has the least influence on the depth of cut. High level of variance (the percentage of variability in the reaction that is interpreted by the formula) confirms that the models fit well to the investigational data.

This paper presents the results of tests obtained for the transformation of geraniol in the presence of garnet as a catalyst by the response surface method (RSM). The method analyzed the influence of the following parameters: a temperature of 50–150 °C, a catalyst concentration (garnet) of 1.0–10.0 wt% and a reaction time of 0.25–24 h. Response functions included the conversion of geraniol (GA), selectivity for conversion to neral (NE) and selectivity for conversion to citronellol (CL). In addition, the influence of all control parameters on each of the response parameters is presented in the form of second-order polynomials. The optimal parameters of the geraniol transformation process were a temperature of 55 °C, a catalyst concentration of 5 wt% and a reaction time of 2 h, for which high values of the GA conversion function and the selectivity of conversion to NE and CL were obtained. For the GA conversion, the optimum was obtained at 94 mol% at 60 °C, a catalyst concentration of 5.0 wt% and a reaction time of 2 h. For NE selectivity, the optimum value was reached at 49 mol% at 60 °C, a catalyst concentration equal to 2.5 (5.0) wt% mole and a reaction time of almost 2 h. For CL selectivity, the optimum value of 49 mol% was obtained for control factors: a temperature equal to 20 °C, a catalyst concentration equal to 5.0 wt% and a response time equal to 2 h. The optimal set of control factors for all power factors is characterized by a temperature of 55 °C, a catalyst concentration of 5 wt% and a reaction time of 2 h.

The paper presents the use of Taguchi method to optimize the cutting of stainless steel by Abrasive Water Jet. Shown are the influence of the most important machining parameters, such a traverse speed, abrasive grains size and concentration of abrasive in the jet on the maximum depth of cut. Analysis of variance - ANOVA was used to determine the effect of machining parameters on the cutting depth. Based on the calculated signal/noise ratios for individual parameters of the cutting process, their impact on cutting depth was determined and optimal process conditions were determined in order to reach the maximum depth of cut. The empirical verification of this process was also performed by comparing the depth of cut predicted and achieved in the tests.

Corundum-based abrasives are commonly used for cutting extremely hard materials like e.g. ceramics by means of abrasive waterjets. Due to a reduced lifetime of the used focusing tubes, this type of abrasive is only applied under special consideration of economic circumstances. The cutting centres which use this technology retain only a small amount of used abrasives because of the limited application of this grain type. Nevertheless, observing the disintegration of particles which have interacted with mostly advanced materials is of scientific interest. Garnet-based abrasives are commonly classified in different grain size classes after sieving to evaluate their recycling potential. Based on a feasibility study, this paper will present some results on achieved cutting data and also shows the geometrical change of the used focusing tubes which was realized by non-destructive examination. The mass loss factor of the used focusing tubes was calculated for different corundum materials and compared with the commonly used in AWJ machining abrasive, garnet. Additionally, cutting and recycling properties of the tested corundum-based abrasive was tested. The disintegration properties of the corundum-based abrasive were monitored by sieving and optical test methods. Particle identification after cutting process (grain or chip) was realized by energy-dispersive X-ray microanalysis (EDX). Finally, the results obtained were used to make a rough calculation for lifetime estimations of the focusing tubes related to the observed wear process.

The size and distribution of abrasive particles have a significant influence on the effectiveness of the cutting process by the high-speed abrasive water jet (AWJ). The paper deal with the abrasive materials disintegration intensity in AWJ cutting during the creation of the abrasive jet. An evaluation of the abrasive materials grabbed after forming in the cutting head was carried out and its grain distribution was evaluated. Used here the arithmetic, geometric and logarithmic method of moments and Folk and Ward method. The influence of abrasive concentration of abrasive materials as alluvial garnet, recycled garnet, corundum, and olivine on grain distribution was studied. A recovery analysis was also carried out and the recycling coefficient for each tested abrasive material was determined.

The paper shows multiple performance optimisation of Hardox steel machining effects by the Abrasive Water Jet (AWJ). An innovative Entropy/VIKOR approach is implemented for the optimisation of parameters in cutting like pressure, feed rate, and abrasive flow rate over cutting depth, cut surface roughness, and angle of cut kerf was conducted. For determine the best set of the process control parameters VIKOR approach with entropy-based weights determining was done. To establish the weights of the initial parameters, it was proposed to calculate individual weights based on entropy. For the multiple criteria optimisation VIKOR approach was assumed.

This paper documents the application of the maximum available pressure for cutting operations using a special pump. This increase of the water pressure, and its conversion to an ultra-high-speed waterjet results in deeper and/or faster cutting. Theoretical aspects of using these ultra-high-speed waterjets are presented. The behavior of this waterjet when it hits the target material is shown. The thermal properties of the waterjet were analyzed. Research into the influence of selected pressure levels on the quality of the cutting edge of processed carbon fiber composite, and into the wear on the water nozzle subjected to ultra-high pressure (UHP) is presented.

This paper presents the results of the Abrasive Water Jet (AWJ) cutting process optimization for Hardox® steel. This type of steel makes it possible to reduce the weight of a work piece and increases the service life of steel elements in comparison with common steel applications. The special combination of features, such as hardness, strength, and toughness, allows using elements with smaller cross-sections. The effect of different pressure levels, traverse speeds and abrasive flow rates, on cutting depth, kerf width and roughness on the cut surface of the Hardox® 500 steel was experimentally tested. In order to determine the most beneficial control parameters of the cutting process, multi-criteria optimization by means of the Gray Relation Analysis (GRA) combined with the Taguchi approach was carried out.

The article presents research on the erosion of the metamorphic rock - marble by the Abrasive Water Jet (AWJ). The fragmentation of abrasive grains during the erosion process is demonstrated. The effect of the cutting process's most important parameters as traverse speed, nozzle ID, and abrasive mass flow rate, on the maximum cutting depth, is shown. To create a mathematical-statistic model of the erosion process, the methodology of the response surface (RSM) was used for modeling. The polynomial equation of the second degree is chosen for developing the regression model. Studies have shown the optimal parameters of the process, to reach the highest depth of the cut. Additionally, the erosion wear of a focusing tube under different process conditions is presented.

Experimental research on high-pressure abrasive water-jet cutting of a popular titanium alloy, grade 5 (Ti6Al4V), is presented. Three types of abrasive material, garnet, olivine, and a cheaper alternative—crushed glass abrasive, were investigated. The influence of basic cutting parameters such as traverse speed and concentration of abrasive on cutting depth was shown, as was the effect of the ratio of the diameter of the water nozzle to the diameter of the focusing tube on the cutting depth. A slower traverse speed resulted in a deeper depth of cut for all abrasive materials. The variation of cutting depth became irrelevant when the concentration of the jet was increased. On basic regression analysis, the cutting depth control models were formulated. The cutting efficiency and the focusing tube wear for all abrasives were compared in order to determine the degree of effectiveness for each abrasive.

The study on the effect of abrasive water jet machining process parameters on micro alloyed steel surface roughness was described. Taguchi method to predict machining parameters of due to minimum surface roughness was used. The influence of pressure, abrasive flow rate and traverse speed on the Rz and Rmax roughness parameters were presented. The optimum combination of processing parameters was established. Verified parameters were tested and the achieved results were compared to predicted values. This method allows limiting the amount of research needed to achieve the desired test results, thereby reducing the time as well as the cost required to carry them out. The Taguchi signal/noise (S/N) ratio enables the assessment of the relevance of the impact of various parameters on the process, which is still not well enough understood. Rezanje z visokotlačnim vodnim curkom je nekonvencionalni postopek obdelave. Rezanje z visokotlačnim abrazivnim vodnim curkom je kompleksnejši proces od konvencionalnih postopkov. Obstoječi modeli za napovedovanje rezultatov rezanja ne podajajo zadovoljivih napovedi na širšem območju procesnih parametrov, še posebej za raznolike materiale. Ena izmed metod modeliranja vpliva procesnih parametrov je metoda Taguchi. Metoda omogoča sistematični pristop k optimizaciji procesa in je uporabno orodje za načrtovanje visoko kakovostnih sistemov. Pri rezanju z abrazivnim vodnim curkom sta tipična optimizacijska kriterija čim večja globina rezanja in čim manjša hrapavost odrezanih površin. V primeru preciznega rezanja je nižja hrapavost rezalne površine ključnega pomena. V članku je predstavljena uporaba metode Taguchi za napovedovanje obdelovalnih parametrov za doseganje minimalne hrapavosti pri rezanju mikrolegiranega jekla. Predstavljen je vpliv tlaka, masnega pretoka abraziva in podajalne hitrosti na parametra hrapavosti R z in R max . S pomočjo uporabljene metode so bile določene optimalne vrednosti procesnih parametrov. Izveden je bil tudi verifikacijski preizkus. Z uporabo metode Taguchi smo preko zmanjšanja potrebnega števila eksperimentov in posledično eksperimentalnega časa dosegli signifikantno znižanje stroškov eksperimentalnega dela. Raziskava je bila opravljena s pomočjo visokotlačne črpalke z ojačevalnikom tipa BYPUMP 50APC. Največji testiran tlak je bil 400 MPa pri volumskem pretoku vode 5 dmsup/min. Uporabljen abraziv je bil Garnet (Almadine) z zrnatostjo 80. Kot material obdelovanca je bilo uporabljeno mikrolegirano jeklo 27MnSiVS6 (DIN 1.5232). To je feritno-perlitno visoko trdnostno jeklo, nizko legirano z manganom in vanadijem. Izbira optimalnih obdelovalnih parametrov je kompleksen proces. Običajno je potrebno izvesti veliko število eksperimentov s pomočjo katerih je moč oceniti njihov vpliv na željeno karakteristiko končnega izdelka. Načrtovanje eksperimentov se z uporabljeno metodo poenostavi. Za implementacijo metode Taguchi je bil uporabljen program Minitab 16. Vpliv kontrolnih faktorjev je bil analiziran z metodo analize variance - ANOVA. Na podlagi eksperimentalnih rezultatov, izračuna razmerja signal/šum in potrditve verifikacijskega preizkusa zaključujemo, da so optimalne vrednosti procesnih parametrov sledeče: - tlak = 360 MPa, - masni pretok abraziva = 80 g/min, - podajalna hitrost = 20 mm/min. Uporabljena metodologija je primerna za raziskave za rezanje novih materialov, s katero je moč pridobiti vpogled v vplive posameznih procesnih parametrov na rezanje.

The need of precision for underwater positioning and navigation should be considered as strict as those present at the sea surface. GNSS provides 4D positioning (XYZT). Each satellite contains two rubidium and two cesium atomic clocks. They are monitored by an atomic clock on the ground, and the entire system is constantly calibrated to a universal time standard, Coordinated Universal Time (UTC). GNSS receivers determine the time T to within 100 billionths of a second without the cost of owning, operating and maintaining an atomic clock. Of particular importance is the measurement of XYZT underwater. We assume that some surface vehicles are additionally equipped with an Acoustic Speaker, which transmits the XY coordinates of the vessel with an indication of accuracy and the time T of the vessel. Submarine vehicles determine their position by help of acoustic signals from several surface acoustic sources using the Time of Arrival (ToA) algorithm. Detection of Spoofing for the Dynamic Underwater Positioning Systems (DUPS) based on vehicles retrofitted with acoustic speakers is very actual problem. Underwater spoofing works as follows: N acoustic speaker on N ships transmit the coordinates {xi,yi,ti}, i=1,N¯. GNSS signals are susceptible to interference due to their very low power (−130 dBm) and can be easily jammed by other sources, which may be accidental or intentional. The spoofer, like an underwater vehicle, receives these signals from N vessels, distorts them and transmits with increased acoustic power. All receivers into the spoofed area will calculate the same coordinates, so the indication of the coincidence of coordinates from a pair of diversity receivers is an indication of spoofing detection.

Existing models of predict the abrasive water jet cutting effects, does not give satisfactory results in a wide area of parameter changes, in particular for different, exotic materials. This implies the need to carry out extensive research in order to expand the empirical database. To optimize the process can be used modern methods referred to as Design of Experiment. One of the methods to determine the effect of parameters on the controlled different technological processes is the Taguchi approach. This method allows to limit the amount of research needed to achieve the desired test results, reducing the time required course for their performance and at the same time their costs. Characterized by Taguchi ratio signal / noise (S / N) enables the assessment of the significance of the impact of various parameters on the process, which is still not well enough understood. The article discusses one method for optimization of cutting tool steel, by high pressure abrasive water jet.

As the demand for precision positioning grows around the world and spreads across various industries, initiatives are being taken to increasingly protect Global Navigation Satellite System (GNSS) receivers from intruders of all kinds, from unintentional industrial interference to advanced GNSS spoofing systems. The timing and cost of these forthcoming satellite navigation safety efforts are difficult to decipher due to the large number of new signals and constellations being deployed. However, it is safe to say that the newly designed anti-jamming and anti-spoofing GNSS systems open up new opportunities for innovative technologies. The false acoustic signal delay is equal to the sum of the spoofer receiving antenna delay, processing delay, and propagation delay from the spoofer to the victim. The victim finds the same location as the spoofer’s receiving antenna, and receivers located in different locations will have the same XYZ. The article presents classifications of terrorist attacks of this type.

In the paper was presented the influence of key machining parameters by Abrasive Water Suspension Jet (AWSJ): abrasive flow rate, working nozzle diameter, and length on the aluminum cutting depth. A high efficiency in the aluminum cutting results from the use of circular motion of the liquid to generate an abrasive water jet. This has become possible due to the special mixer in which the water and abrasive mixture is generated directly under high pressure. The research determined the best dimensions of the working nozzle and level of abrasive flow rate to achieve the biggest cutting depth were achieved.

Existing models of predict the abrasive water jet cutting effects, does not give satisfactory results in a wide area of parameter changes, in particular for different, unusual materials. This implies the need to carry out extensive research in order to expand the empirical database. To optimize the process can be used modern methods referred to as Design of Experiment (DoE). One of the methods to determine the effect of parameters on the controlled different technological processes is orthogonal array design, also called the Taguchi approach. This method allows to limit the amount of research needed to achieve the desired test results, reducing the time required course for their performance and at the same time their costs. Characterized by Taguchi ratio signal / noise (S / N) enables the assessment of the significance of the impact of various parameters on the process, which is still not well enough understood. The article discusses one method for cutting optimization of aluminum alloy by high pressure abrasive water jet.

U radu se daje primjena fraktalne analize u jednostavnoj procjeni kvalitete površina obrađenih vodenim mlazom, naročito nakon rezanja abrazivnim vodenim mlazom. Ovom će se analizom omogućiti otklanjanje subjektivne procjene obrađivanih površina. Na taj će se način osigurati točna procjena kvalitete površine kao i mogućnost da se objektivno usporedi kvaliteta odrezanog ruba dobivenog primjenom različitih parametara., The paper presents the fractal analysis application for a simple evaluation of the quality of waterjet treated surfaces, especially after abrasive waterjet cutting. This analysis will enable the elimination of subjective assessments of treated surfaces. This will ensure a clear estimate of the quality of the surface and the ability to objectively compare the quality of the cutting edge obtained by using different cutting parameters.

Modern production processes are becoming increasingly complex. At the same time, customers require high-quality products at the lowest price. This situation increases the importance of optimisation of production processes from the preparation of production to its implementation. Various methods of process optimisation have been devised to respond to the emerging phenomena including organisational aspects, device design, quality engineering and process automation. The TOPSIS method is used to make multi-criteria decisions. In this paper, a methodological study of this method was carried out, indicating conditions of applicability, assumptions and limitations, and the use of the TOPSIS method in the IT system supporting the optimisation of industrial processes on the example of waterjet cutting optimisation.