نشریه کارافن
سال نوزدهم شماره 59 (پاییز 1401)

In friction stir welding process, a non-consumable rotary tool is used which consists of a pin and a shoulder. The tool/workpiece friction results in stirring, plastic deformation, and joining. It is the shoulder penetration which leads to thinning of the upper sheet and remaining of a hole. In this study, a stationary shoulder was used to investigate the spot welding of a non-alloyed aluminium sheet to address the mentioned drawback. The aim was to investigate the effects of tool rotational speed with two levels of 1000 and 2000 rpm, tool shoulder diameter with two levels of 20 and 24 mm, and plunge depth with two levels of 3 and 3.5 mm on the microhardness, strength, and microstructure of the welded samples. Feed rate and dwell time were constantly set to 20 mm/s and 10s, respectively. Optimization was carried out in three modes including maximum strength, maximum hardness, and a combination of the maximum strength and hardness. In the first mode, the maximum strength was 1389.51 N in the specimen welded with a tool rotational speed of 2000 rpm, plunge depth of 3 mm, and tool shoulder diameter of 24 mm. In the second mode, the highest micro-hardness value was 91.33 HV in the specimen that was welded with a tool rotational speed of 1000 rpm, plunge depth of 3.5 mm, and tool shoulder diameter of 20 mm. Finally, in the third mode, the combination of the highest strength and micro-hardness values were 1389.51 N and 85.66 HV, respectively.

This paper presents a combination of innovative methods for optimization using the integration of the evolutionary difference algorithm (DE) and the recipient's version of the immune system algorithm. In this paper, at the mutation stage, the particle swarm algorithm (PSO) was used to determine the value of the mutation coefficient using the immune system algorithm. Therefore, the algorithm modified its evolutionary method and searched for the optimal jump coefficient. The proposed model was tested on milling operations to determine its effect on the optimization of milling parameters. The results of the hybrid approach for the case study were compared with those of ant colony algorithm, body immunity, hybrid immune algorithm, genetic algorithm, HDRE approach, and the proposed values ​​of machining handbooks. According to this comparison, the development ratio between the proposed algorithm and other approaches were as follows: ant colony algorithm was 5.7%, immune algorithm was 4.5%, hybrid immune algorithm was 3%, genetic algorithm was 8.5%, HDRE approach was 2% and handbook recommendation was 300%.

The material forming through the forging process is one of the manufacturing methods in which the metal is compressed or subjected to high forces to create high-strength parts. Before the process, a lubricant is added to the mould to increase the metal flow, reduce friction and wear, and help separate the final part from the mould. The lubricant in hot forging process and lubrication are key factors for increasing production quality. One of the best ways to study the effect of lubricants in this process is ring compression testing (RCT). In this study, the effect of nanoparticles (Aluminum oxide (AL2O3) and Nano-glass) as an additive to base oil (SAE10) at 1050 °C on the friction behaviour of 7-17 PH stainless steel using RCT and finite element analysis (FEA) was studied. Finally, the importance of using nano-lubricants in hot forging process was investigated. The results showed that nanoparticles as lubricant additives performed better than conventional lubricants (such as graphite) for the frictional behaviour of 7-17 PH stainless steel in hot forging process. For 7-17PH stainless steel at 1050 ° C, the friction factor was reduced by approximately 36% with the addition of AL2O3 nanoparticles and by approximately 40% with the addition of glass nanoparticles. Therefore, adding nano-glass presented better results compared to AL2O3 nanoparticles.

Due to the fast growth of energy consumption globally, distribution networks are seeking a solution to supply the required energy, considering the technical and economic conditions. In this research, distributed resources were planned in the distribution network, taking into account the interests of both the owner of the resources and the operation of the network. The objective function was designed to serve the interests of the owners of the distribution network, including the improvement of network parameters and the owners of distributed generation resources, which included the maximum possible profit from the sale of energy. The objective function was considered to be a combination of several linear functions. Due to the high reactance ratio in radial networks, forward-backward sweep load flow was used. Necessary constraints for the network with quality indicators were considered as equality and inequality constraints. For the location of distributed generators on the buses, the sensitivity factor was used and to achieve the final response of the objective function, the teaching–learning-based optimization (TLBO) algorithm was used and compared with particle swarm optimization. A standard 37-bus radial network was considered to evaluate the results of the proposed method. The simulation results show an improvement in power quality of the network and an increase in the profits of the owners of distributed generators.

In structural designs, lateral strength systems are used to withstand lateral loads such as earthquakes and winds. Bending frame system with divergent bracing and Bending frame system with steel shear wall are two of these systems that have both advantages and disadvantages. Thus far, various research has been conducted separately on one of the above systems. This research seeks to numerically investigate the combination of steel shear wall with eccentric bracing under cyclic loads. To this aim and to ensure the numerical results, a laboratory sample was validated and then 126 models were modeled in seven modes by considering different arrangements of divergent bracing and steel shear wall in three openings of a floor with Abaqus software. In these samples, the placement of divergent bracing and steel shear wall in addition to their placement in different openings were evaluated taking into consideration different thicknesses of steel shear wall sheets and different numbers of the downspout with the aim of assessing the effect of combining steel shear wall and divergent bracing in steel frames. The results of the analysis indicated that the lowest increase in force was related to the sixth mode of modeling, the combination of steel shear wall in two openings and bracing in one opening and downspout number 10 with a value of 15.57% increase in force. Furthermore, the highest amount of force was related to the third mode of modeling using two divergent bracing openings and one opening of steel shear wall and downspout number 12 amounting to 77.45% increase in force.

Evaluating the seismic performance of structures is one of the interests and responsibilities of structural and earthquake engineers. The eccentric bracing system has always been one of the most important and widely used structural systems due to its high strength, stiffness and ductility. These structures are usually designed with horizontal shear and bending links. In this research, using nonlinear dynamic analysis, the seismic response and performance of these structures under near-field records with and without vertical components in addition to considering the effect of soil-structure interaction were investigated. Therefore, three types of frames of 4, 8 and 12 floors were designed and modeled non-linearly using the finite element method in Perform-3D software. Maximum displacement and displacement of roof residue, floor drift and base shear of these structures were selected and studied as engineering demand parameters. The results showed that the structure with horizontal shear link had much better responses than the frame with horizontal bending link. In addition, the effect of soil-structure interaction increased the roof displacement and reduced the base shear on the structure.

This research study was focused on development of novel potentiometric sensor for the determination of thallium (III) ions in water solutions. Ion-selective electrodes based on screen-printed graphite electrode and carbon rod electrode described and modified solid-state screen-printed and carbon rod electrodes with thallium (III)-imprinted polymer as ionopher. The ion-selective electrode was prepared by dispersing the thallium (III)-imprinted polymer particles in 2-nitrophenyloctylether as a plasticizer and then embedding them in a polyvinylchloride polymeric matrix. The Tl (III)-ion selective electrode showed a Nernstian response for thallium (III) ions over the dynamic concentration range of 0.49 to 20.5 µM, with a slope of 19.6 mV per decade. One of the significant points was the selectivity coefficient of the prepared ion-selective electrode. The selectivity of this electrode for other ions was less than 1.1× 10-3 and this indicates the selectivity of the electrode to thallium (III) ions and other ions was less disturbing.

Nowadays, identifying the risks of manufacturing industries is an effective factor in improving the performance of the health supply chain. This study aimed to identify and evaluate the risks of the manufacturing sector in the livestock and poultry feed supply chain in Golestan Province, Iran. For this purpose, first, the risks related to livestock and poultry feed industrial units were identified using the Failure Mode and Effects Analysis (FMEA) and then, by designing the Risk Breakdown Structure (RBS) approach, risk identification process was structured, which increased the comprehensiveness of the identification phase in terms of covering the features and characteristics of the project. Moreover, by using the fuzzy best-worst model (F BWM) and the Fuzzy DEMATEL (F DEMATEL) method, the weights and internal relationships of the criteria were calculated, respectively. For weighting and final prioritization, a combination of the two methods of F BWM and F DEMATEL was used. The present study was applied and descriptive in terms of purpose and nature, respectively. The data was both quantitative and qualitative, and library and field methods were used for data collection. According to the research results, among the risks of the production sector in the livestock and poultry feed supply chain of Golestan Province, the risk of the COVID-19 pandemic and the risk of increasing poverty were the highest and the lowest priorities, respectively.

Group  is called metacyclic if it contains a normal cyclic subgroup such that the quotient group  is also cyclic. In this paper, two conjectures proposed by Abdollahi et al. (2006) for a family of finite non-abelian metacyclic prime power groups  were investigated. For this purpose, first, the metacyclic groups were categorized into three Types (families) of the non-isomorphic groups. Next, by using the size of centralizers and also equality of the conjugacy vector type ctv (G) of these groups, the necessary and sufficient conditions under which two non-abelian finite metacyclic prime power groups have the isomorphic non-commuting graphs were determined. The first conjecture of Abdollahi et al. for the three families of the classified groups was proven to be true. Likewise, the second conjecture held for some restrictions on the parameters of group . Finally, it was demonstrated that there were non-isomorphic groups with the same non-commuting graphs.