The aim of this work is to optimize the hardness of anodizing aluminum coating by design of experimental method. Various parameters affect the hardness of these coatings among which time, temperature and pulse current parameters (current density limit, frequency and duty cycle) were considered. According to this, mentioned parameters in different levels were considered as input variables. Also, the effect of parameters on the hardness of anodizing aluminum coating was obtained as a mathematical model. The final model was achieved by Analysis of variance which was used for attaining the best method to predict the maximum hardness of these coatings. The most effective variables and optimized hardness of anodizing aluminum coating were obtained by using the mathematical model. Experimental results showed that temperature and quadratic behavior of duty cycle were the most important terms on the hardness of these coatings. Furthermore, the maximum hardness of this coating was 491Hv, which was attained at the maximum and minimum current densities of 4. 09, 1. 23 A/dm2, frequency of 146. 94 Hz, time of 29. 50 min, duty cycle of 65. 16% and the bath temperature of 3. 13oC.

Directed Acyclic Graphs stand as one of the prevailing approaches for representing causal relationships within a set of variables. With observational or interventional data, certain undirected edges within a causal DAG can be oriented. Performing intervention can be done in two different settings, passive and active. Here, we prove that an optimal intervention set can be obtained based on the minimum vertex cover of a graph. We propose an algorithm that efficiently identifies such an optimal intervention set for chordal graphs within polynomial time. Performing intervention on this optimal set recovers all the undirected edges in graph G, regardless of the underlying ground truth DAG. Furthermore, we present an algorithm for evaluating the performance of passive algorithms. This evaluation provides insights into how many intervention steps of a specific algorithm are required to recover all edges in the causal graph for any possible underlying ground truth in the equivalence class. Experimental findings underscore that the number of nodes in the optimal intervention set increases with growing the number of nodes in a graph, where the edge density is fixed, and also increases with the rising edge density in a graph with a fixed number of nodes.

Directed Acyclic Graphs stand as one of the prevailing approaches for representing causal relationships within a set of variables. With observational or interventional data, certain undirected edges within a causal DAG can be oriented. Performing intervention can be done in two different settings, passive and active. Here, we prove that an optimal intervention set can be obtained based on the minimum vertex cover of a graph. We propose an algorithm that efficiently identifies such an optimal intervention set for chordal graphs within polynomial time. Performing intervention on this optimal set recovers all the undirected edges in graph G, regardless of the underlying ground truth DAG. Furthermore, we present an algorithm for evaluating the performance of passive algorithms. This evaluation provides insights into how many intervention steps of a specific algorithm are required to recover all edges in the causal graph for any possible underlying ground truth in the equivalence class. Experimental findings underscore that the number of nodes in the optimal intervention set increases with growing the number of nodes in a graph, where the edge density is fixed, and also increases with the rising edge density in a graph with a fixed number of nodes.

Introduction: Lipase (EC 3.1.1.3) is one of the most important classes of industrial enzymes. The non-conventional yeastYarrowia lipolytica is non-pathogenic to humans and is known as safe for some industrial processes. This yeast can produce different types of lipase. Extracellular lipase production depends on medium composition and environmental conditions. Materials and Methods: Olive oil as carbon source, yeast extract and tryptone as nitrogen sources and pH in different levels were optimized for lipase production by mutant strainYarrowia lipolytica FDY1390 with Taguchi experiment design method. Qualitek-4 software was used to Taguchi experiment design method. Results: The highest level of lipase production (340 U/mL) was obtained in medium containing 20 g/L Olive oil, 15 g/L yeast extract and tryptone, pH 4 after 72 h of fermentation process. Conclusion: Optimization of lipase production reduces the costand various industries use this enzyme.

In this paper, design and calculation method of a swirl injector with tangential inlets has been presented considering some known assumption. The injector designed based on the above method has been manufactured using CNC. Formation and development phenomena of air core within swirl injectors and their simulation is complicated due to two-phase swirl turbulent flow with common free surface. Therefore, in order to predict exit flow properties and investigate test results fitting, internal flow analysis has been performed. The results show agreement between numerical simulations and experiments, and air core has been formed correctly within injector. Two-phase and free surface simulations have been carried out using VOF method and turbulence has been modeled using k-model. The results have been discussed completely in the text.

Heat exchangers are one of the most important devices of mechanical systems in modern society. Most industrial processes involve the transfer of heat and more often they require the heat transfer process to be controlled. A heat exchanger is the heat exchanged between two media, one being cold and the other being hot. There are different types of heat exchanger, but the type which is widely used in industrial application is the shell and tube. In this study, experiments conducted based on fully replicable five-factor, five-level central composite design. Regression modelsare developed to analyse the effects of shell and tube heat exchange process parameter such as inlet temperature of hot fluid and flow rates of cold and hot fluid. The output parameters of a heat exchanger are used for analysing the direct and interactive effects of heat exchange process parameters.

In this paper, the effect of the Gurney flap parameters such as the angle of attack, Reynolds number, angle and height of the flap and its location from the escape edge on the lift coefficient of a symmetric airfoil is considered with the help of simulation in computational fluid dynamic software of Fluent. The turbulence model k-ε is used for the two-dimensional domain. Also, the value of the lift coefficient is introduced as a function of effective parameters by the design of experiment (DOE) method and using the backward elimination regression model which is a statistical method for selecting the model and estimated error terms. The value of the airfoil lift coefficient can be determined and predicted by the obtained function. The numerical values derived from the function of the lift coefficient resulted from the design of experiment method are in good agreement with other valid papers. The results show that at the constant attack angle by increasing Gurney flap height, lift coefficient increase. On the other hand, at the constant height of the Gurney flap, this coefficient decreases with increasing angle of attack. Moreover, the lift coefficient increased by increasing the distance of the Gurney flap from the airfoil escape edge at a 90-degree angle and 1. 5%, as well as increasing the Reynolds number at a constant height of a Gurney flap.

In the present study, the thermal performance of the air-side compact heat exchanger of an automotive condenser in the three-dimensional model has been numerically simulated based on the design of experiment (DOE). For this purpose, the effective geometrical parameters such as fin pitch, louvre pitch, louvre angle, fin height and fin width and their effects on condenser thermal performance are studied and investigated. Finally, for parameters effective on the compact heat exchanger operation, such as air-side heat transfer coefficient, static pressure drop and other thermal parameters, relationships are extracted based on the design of experiment which decrease the computational cost with the least error. The results show quantitatively that by increasing the fin length, louver angle, louver pitch and decreasing the fin pitch, the heat transfer rate increases by about 42%. Also, the results show that the heat dissipation, heat transfer coefficient and pressure drop, have improved by 8. 1%, 5% and 10. 5% respectively compared to recent numerical results. Eventually parametric studies including the effect of ambient temperature, condenser wall temperature and vehicle speed on thermal performance and pressure drop are presented.