This paper investigates the influence of the fuel injector nozzle geometry on the liquid fuel contraction coefficient and Reynolds number. The main three fuel injector nozzle geometry parameters: nozzle diameter (d), nozzle length (l) and nozzle inlet radius (r) have a strong influence on the liquid fuel contraction coefficient and Reynolds number. The variation of the nozzle geometry variables at different liquid fuel pressures, temperatures and injection rates was analyzed. The liquid fuel contraction coefficient and Reynolds number increase with an increase in the nozzle diameter, regardless of the fuel injection rate. An increase in the r/d ratio causes an increase in the fuel contraction coefficient, but the increase is not significant after r/d = 0.1. A nozzle length increase causes a decrease in the fuel contraction coefficient. Increase in the nozzle length of 0.5 mm causes an approximately similar decrease in the contraction coefficient at any fuel pressure and any nozzle length. Fuel injectors should operate with minimal possible nozzle lengths in order to obtain higher fuel contraction coefficients.

This Publication has to be referred as: Cekic, A[hmet]; Muhamedagic, K[enan]; Cohodar, M[aida]; Begic-Hajdarevic, D[erzija] & Biogradlija, S[amra] (2019). Experimental Investigation of Effect of Overhang Tool Length on Tool Vibration and Surface Roughness, Proceedings

This paper presents an approach for the optimization of laser cutting process of aluminium alloy with multi-response outputs based on the Grey relational analysis (GRA). For experimental design, tests are planned based on Taguchi's L9 orthogonal array. The laser cutting parameters such as laser power and cutting speed are optimized with consideration of multi-response outputs such as top kerf width and surface roughness. It is observed that the laser power has stronger effect on multi-response outputs than cutting speed. According to multi-response optimization results, which are obtained from the highest value of the grey relational grade (GRG), the optimum combination is 2500 W laser power and 2.4 m/min cutting speed to simultaneously minimize the kerf width and surface roughness.

In this paper was analyzed and experimentally investigated two additive technologies: Stereolithography -SLA i Fused Deposition Modeling -FDM. The dimensional accuracy (deviation from the given dimensions in relation to the previously defined 3D CAD model as well as the surface roughness of the printed samples by the additive technologies FDM and SLA) was analyzed. The process parameters of these additive technologies were optimized in order to achieve better dimensional accuracy and less surface roughness on the products. Additionally, a comparison of FDM and SLA additive technologies was performed.

Ḥadiths that have been discussed in this paper consist of narrations regarding divine attributes and having some problematic meanings between supporters of Bishr al-Marīsī and ʿUthmān al-Dārimī. These narrations were mostly accepted denounced (munkar) by Bishr alMarīsī and his supporters due to having an anthropormophist and corporealist content about God. They rejected divine attributes according to their understanding of God based on incomparability (tanzīh) which provided by Muʿtazilite approach towards divine attributes even though they conveyed some features of Ahl al-Ra’y. They found contradicted of attributing human features to God based on their tanzīh understanding, therefore, they interpreted such this kind of narrations in terms of their approach or rejected at all. At the other hand, a hard Ḥadith scholar ʿUthmān al-Dārimī believed that one should accept divine attributes as they are in the Qurʾān and Sunna. According to his belief, he considered the explicit meanings of the narrations without interpretation of divine attributes, and based on his perspective he denied Bishr al-Marīsī (d. 218 /833) and his supporters’ interpretations claiming they would cause divesting God of all attributes (ṭaʿtīl). He argues that these narrations should be taken into considerations based on their explicit meanings. The discussions on these ḥadiths are important due to showing different approaches of scholars from the schools of Ahl al-Raʾy and the ones from Ahl al-Ḥadīth towards the ḥadith during the period when the main Ḥadith works were collected. Discussions on the narrations studied in this paper reveal two schools’ understandings of divine issues, their approaches to divine attributes, as well inform us their perspectives of ḥadith in general.

This paper presents the use of Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method to determine the optimum process parameters in plasma arc cutting of stainless steel. Two input process parameters, cutting speed and plasma gas pressure are considered and experiments are conducted based on Taguchi L9 orthogonal array. After performing the experiments, the surface roughness, cut perpendicularity and kerf width are measured. The analysis of variance (ANOVA) are performed in order to identify the effect of each input process parameters on the output responses. The results indicate that TOPSIS method is appropriate for solving multi-criteria optimization of process parameters. Results also showed that cutting speed of 2500 mm/min and plasma gas pressure of 6 bar are the optimum combination of process parameters.

For increase of industrial competitiveness and rapid market entry with new products, various additive technologies are increasingly being used today. This paper presents the experimental results of the study the impact of the Fused Deposit Modeling (FDM) process parameters on product quality using different materials. The work is primarily focused on optimizing the important process parameters for the FDM process using the new unexplored material. The making of test samples for dimensional accuracy and mechanical properties tests was carried out on two devices, Flashforge Finder and Ultimaker 3 with two different materials: standard PLA and new composite wood (polymer + wood) material. The obtained results show that new materials that can be produced from wood waste with a certain percentage of adhesives can be used, but before that, process parameters must be precisely defined in order to achieve satisfactory quality of the final products. In this way it has a positive impact on the environment, because wood is a natural and ecologically pure material (CO2 neutral).

This paper presents the use of Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method to determine the optimum process parameters in plasma arc cutting of stainless steel. Two input process parameters, cutting speed and plasma gas pressure are considered and experiments are conducted based on Taguchi L9 orthogonal array. After performing the experiments, the surface roughness, cut perpendicularity and kerf width are measured. The analysis of variance (ANOVA) are performed in order to identify the effect of each input process parameters on the output responses. The results indicate that TOPSIS method is appropriate for solving multi-criteria optimization of process parameters. Results also showed that cutting speed of 2500 mm/min and plasma gas pressure of 6 bar are the optimum combination of process parameters.