In the present research, the authors have attempted to examine the compressive strength of conventional concrete, which is made using different aggregate sizes and geometries considering various curing temperatures. To this end, different aggregate geometries (rounded and angular) were utilized in various aggregate sizes (10, 20, and 30 mm) to prepare 108 rectangular cubic specimens. Then, the curing process was carried out in the vicinity of wind at different temperatures (5 °C < T < 30 °C). Next, the static compression experiments were performed on 28-day concrete specimens. Additionally, each test was repeated three times to check the repeatability of the results. Finally, the mean results were reported as the strength of concrete specimens. Response Surface Analysis (RSA) was utilized to determine the interaction effects of different parameters including the appearance of aggregates (shape and size) and curing temperature on the concrete strength. Afterwards, the optimum values of parameters were reported based on the RSA results to achieve maximum compressive strength. Moreover, to estimate concrete strength, a back-propagation neural network (OBPNN) optimized by a genetic algorithm (GA) was used. The findings of this study indicated that the developed neural network approach is greatly consistent with the experimental ones. Additionally, the compressive strength of concrete can be significantly increased (about 30%) by controlling the curing temperature in the range of 5–15 °C.

Nanophotocatalysts are applied for different applications, and their usage has been enhanced remarkably since a decade. On the other hand, cross-coupling reactions of C−N bonds have found increasing popularity for coupling derivatives of organic compounds such as aniline using diverse catalysts. Nanoheterogeneous photocatalysts can offer suitable platforms for the C−N coupling of aniline derivatives. However, the design of a photocatalyst on the nanoscale with remarkable activity and selectivity, made of noble-free elements, is highly welcome. In this study, the half-filled electronic configuration and shallow trapping properties of Fe were employed to reduce the energy band gap of the system. Moreover, the large ionic radius of lanthanide leads to large surface activity. Thus, bi-and trinuclear nano-oxide nanophotocatalysts were synthesized based on the titanium, iron, and lanthanide elements (Ti x Fe y O z , Ti x Fe y La m O z ) to obtain logically designed photocatalysts with high selectivity, durability, and operation speed under visible light. In addition, designing photocatalysts in the nanoscale was the ultimate target of this study to use the highest benefit of the nanoscale, which is high surface activity. The developed nanophotocatalysts were used for coupling aniline and its 10 derivatives under visible light. The mechanism of the migration of electrons and the C−N reaction was also investigated in detail. In addition, both obtained nanophotocatalysts were applied in five different solvents and eight different conditions so the best condition for the reaction could be determined. Furthermore, the photocatalytic mechanism was studied in detail. The final nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), inductively coupled plasma mass spectrometry (ICP-MS), Brunauer−Emmett−Teller (BET) surface activity, Barrett−Joyner− Halenda (BJH) method, UV−vis spectroscopy, photoluminescence emission spectra, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), NMR spectra, mass spectra, and CHN elemental analysis. Both nanocomposites exhibited high photocatalytic activities in coupling aniline and its derivatives under visible light. However, the Ti x Fe y La m O z nanophotocatalyst showed a higher activity (90% conversion to obtain 2,4 dinitro-n-phenylaniline) than the Ti x Fe y O z nanophotocatalyst (68% conversion to obtain 2,4 dinitro-n-phenylaniline), which is mainly due to its higher surface activity because of its lanthanide content.

The main aim of the present paper is to assess the fatigue lifetime of ductile cast iron knuckles as one of the critical components of an automotive steering system. To this end, a real driving path, including various maneuvers, such as acceleration, braking, cornering, and moving on various types of road roughness, was considered. Different load histories, which are applied on various joints of the component (i.e., lower control arm, steering linkage, and Macpherson strut), were extracted through Multi-Body Dynamics (MBD) analysis of a full vehicle model. The achievements of previous studies have proved that the steering knuckle fails from the steering linkage and due to the rotational motion. Therefore, only this destructive load history was considered in future analyses of the present study. The CAD model was created using Coordinate Measuring Machine (CMM) data and some corrections in CATIA software. Furthermore, transient dynamic analysis was performed, and the time history of von Misses equivalent stress was obtained at the root of the steering linkage (which is exactly the location of failure based on the laboratory data as well as finite element simulations validated by the author in the previous studies). To predict the fatigue life of a component, two different methodologies were considered. Firstly, some well-known criteria were employed for equalization of load spectrum to a Constant Amplitude Loading (CAL). Then, fatigue analysis under sinusoidal loading was performed. Secondly, the fatigue life of the component considering Variable Amplitude Loading (VAL) was predicted using the Critical Plane Method (CPM), employing the Rain-flow cycle counting technique, and utilizing the Miner–Palmgren damage accumulation rule. Eventually, to evaluate the prediction accuracy of different methodologies, the obtained results were compared with the full-scale axial variable amplitude fatigue test which was performed by the corresponding author. The results indicated that the prediction of variable amplitude fatigue lifetime by Finite Element (FE) analysis in the time domain has about 21% error compared to reality. Additionally, the relative error between the results obtained from two different methodologies is about 20%, which is acceptable due to the scattering of the fatigue phenomenon results, the complex geometry of the part, and the complicated loading.

Recently, V-engines with a small angle of camber are more widely used as power units for passenger cars, especially because of the reduced engine length, and the transverse dimensions are almost the same as in-line ones. All this leads to an increase in overall engine power. However, due to the small camber angle between the parallel rows of cylinders, the intersection of the cylinders in their lower part may occur. To prevent the latter, significant multidirectional desaxial is used. Moreover, the calculation of the dynamics of similar engines introduces a number of features, including balancing the inertia forces and their moments from the reciprocating moving and rotating masses. The article discusses the balancing of 5-cylinder four-stroke VR type engines with desaxial crank mechanism and uniform flash alternation. The formulas allowing to find and analyze moments of the inertia forces of the reciprocating and rotating masses arising in VR-5 engines are given by the given value of the cylinder camber angle, the ratio of the crank radius to the connecting rod length and the relative displacement of the cylinder axis. A method of balancing the moments of inertia forces of the reciprocating and rotating masses is proposed and the results of the presented dynamic study of a VR-5 engine using analytical, software and graph-analytical methods.

In this study, the potential of using solar energy which would be catch by a flat plate heat exchanger is investigated as the input source of heat to a single absorption refrigeration system of lithium bromide-water. Validating the simulation, results was compared to the theoretical and empirical results of previous studies. The daily operation of the refrigeration system for atmospheric data in Tehran’s typical day, shows that there would be an optimum number of flat plate collectors in the solar absorption system, which is 50 with a surface area of 5/38 square meters. This number, in addition to have a proper performance factor, can provide a cooling load of about 5 kilowatts, while the power consumption of pumping in the combined cycle is not considerable. Finally, the effect of different performance parameters including temperature of the heat generator, evaporator temperature on the daily efficiency of the solar refrigeration cycle has been investigated. As the evaporator temperature increases, the daily performance of the solar refrigeration system is increased.