The aim of this study is to evaluate the effect of preheating on composite resins' mechanical and physical properties. preheating of composite resins positively affects the degree of conversion, viscosity, microleakage, marginal adaptation, microhardness and color change however, the flexural strength is adversely affected.

The main problem in the utilization of bran into rice bran oil is easy to rancid because of the high lipase enzyme content. The preheating process on the bran using an oven serves to inactivate the lipase enzyme and increase oil yield. Aim this research is to find out the effect of preheating temperature and preheating time on physical properties (yield, color, and melting point) and chemical properties (free fatty acid, antioxidant activity, phenol levels, and fatty acid profiles) crude black rice bran oil (Oryza sativa L.) cultivar Mutiara. The experimental design used Complete Randomized Design (CRD) with of two factors, the temperature and time heating. The research were analyzed using One Way Anova with significance level α = 0,05. The research showed variations in temperature and pre heating time significant effect on the physical and chemical characteristics of crude black rice bran oil. The preliminary heating treatment at 110°C for 10 minutes is the best treatment. The physical characteristics of yield 9,62%, color is obtained value L* 33,70, a* 2,99, b* 1,08, and whiteness degree 33,62 and melting point 28,50-34,50°C. Chemical characteristics free fatty acid level 18,43%, antioxidant activity 76,69%, and phenol level 0,46%. The fatty acid profiles selected black rice bran oil cultivar Mutiara is myristoleic acid 0,44%, palmitoleic acid 20,04%, elaidic acid 2,01%, linoleic acid 34,91%, linolelaidic acid 0,32%, γ-linolenic acid 38,37%, α-linolenic acid 2,88%, eicosanoic acid 0,65%, and eicosadienoic acid 0,38%. Based on these results, black rice bran oil is suitable for use as cooking oil and oleogel which is applied to fat and oil based spread products.

A comprehensive thermodynamic analysis is used to characterize the exergy destruction rate in any part of the solar air preheating system (SAPHS) and calculate its efficiency. The system consists of a solar evaporator, a heat exchanger to air preheating and an auxiliary pump. A computer simulation program using EES software is developed to model and analyses the SAPHS. The system provides preheated air during the year. The thermodynamic analyses involves the determination of effects of air preheating (APH) heat exchanger pinch point temperature, solar radiation intensity and overall heat loss coefficient of the solar evaporator on the performance of the SAPHS. The result showed that the main source of the exergy destruction is the solar evaporator. In the solar evaporator, 115. 9 kW of the input exergy was annihilated. Other main source of exergy annihilation is the APHHE, at 7. 45 kW. The overall energetic and exergetic efficiencies of the SAPHS were 70. 11% and 9. 766%, respectively.

This study aims to place Mg2Si reinforcing particles in the inner wall of aluminum matrix composite tube and optimize the microstructure and hardness of the mentioned wall using temperature parameters. Upon application of Al-Si alloy, creation of in-situ Mg2Si particles in this alloy system, and production of the pipe as a result of the low density of Mg2Si particles based on the centrifugal casting method, these reinforcing particles would be accumulated in the inner wall of the pipe. In this study, the effect of dissolution, aging, mold preheating, and pouring temperature on the hardness of the inner wall ofAl-15 wt. % Mg2Si alloy was investigated, and the most optimal manufacturing conditions as well the interaction among the variables were determined using Design Expert software to achieve the highest hardness. Of note, the most effective variable among the mentioned variables was heat treatment temperature, and the best temperature was about 535 °C. According to the findings, the best pouring temperature was obtained as around 700 °C; hence, a higher temperature is needed to preheat the mold to obtain reinforcement with uniform placement.

Hot machining is a type of cutting operation that an external heat source is used to pre-heat and consequently reduce the yield strength of the workpiece material. In this study, the conventional and hot turning of AISI630 hardened stainless steel, which is widely used in energy equipment, aerospace, and petrochemical industries, have been evaluated in both numerical and experimental methods. Simulation of the turning process is carried out by finite elements method (FEM) using AdvantEdge software. To predict chip morphology and cutting forces, the 2D and 3D FEM analyses have been used, respectively. The numerical analysis showed that hot turning in 300°C causes a reduction of 28% in cutting forces and consequently decreases stressed on the cutting tool. It is found that the main factor affecting the fluctuations of the cutting forces in turning of hardened AISI630 is the saw-tooth formation phenomenon (chip segmentation) as well as the shear band generation due to thermal softening of the workpiece material. Furthermore, the relation between cutting force fluctuation and the machined surface roughness has been investigated applying numerical analysis and experimental data. The results of roughness measurement revealed that hot turning in 300°C reduces the machined surface roughness up to 23%. In addition, it has been observed that hot turning technique decreases side flow and surface damages in comparison to conventional turning.