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Nowadays, composite sheets have been increasingly developed in various applications due to their better corrosion and wear resistance as well as higher strength and formability. Of these, Al/SS bilayer sheets have been used in the food and automotive industries due to their favorable performance and low cost. In this research, the bonding strength of Al1050/AISI304 bilayer sheets fabricated by cold roll bonding has been investigated experimentally. At first, the design of the experiment was carried out using the surface response method, taking into account the thickness of the layers and the rolling reduction ratio, bilayer sheet using the rolling bonding method. In this research, for the first time, the bonding strength of Al/SS bilayer sheets fabricated by cold rolling bonding method and its optimization have been investigated. The bond strength was extracted using T peeling test. Then, using the linear regression method, a mathematical-experimental relationship was presented to obtain the peeling strength in terms of the thickness of the layers and the reduction ratio. The obtained results were analyzed using statistical methods and the table of coefficients, the table of residuals and the analysis of variance table of the data related to bond strength were presented and the adequacy of the presented model was examined. The results showed that by reducing the reduction ratio in the cold rolling process and also reducing the initial thickness of the sheets, the bond strength of the bilayer sheet has decreased. Then, bond strength optimization was done as a function of input parameters. The results indicated that the bonding strength reached its maximum level at the thickness of the aluminum layer = 2 mm, the thickness of the stainless-steel layer = 1.3 mm and reduction = 75%. [ABSTRACT FROM AUTHOR]

Machining of metal matrix composites (MMC) is a challenging process as they are difficult to cut and cutting tools get worn out in a short time. In this paper, the performance of two industrial carbide grades and a cubic boron nitride (CBN) tool are assessed when machining of AZ91/SiC composites. Mg-based composites with different volume fractions and particle sizes are machined at various cutting conditions to evaluate the tools wear resistance and finished surface. The surface of the worn-out tools and machined samples are analyzed by scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and roughness tester. Results revealed that the tool wear increased for composites reinforced by smaller particles regardless of the tool type. Additionally, tool grade TH1000 resulted in longer tool life when machining of Mg-based composites compared to the CP500 grade so that at a cutting speed of 70 m/min and feed rate of 0.1 mm/rev, tool life improved nearly 250%. CBN tools showed the best performance when machining of Mg-based composites as tools became worn out after 255 s which is considerable compared to carbide tools. Also, the finished surface caused by cemented carbide CP500 indicated the worst quality. [ABSTRACT FROM AUTHOR]

Combined Heat and Power (CHP) systems have attracted substantial interest in the past decades as they offer higher thermal efficiency than single power generation systems. Various parameters affect the performance of a cogeneration system, including environmental and operating conditions of gas turbine and Heat Recovery Steam Generator (HRSG) system. In this study, the effects of 15 substantial parameters on the performance of a CHP system are investigated using Thermoflow software. The most influential parameters are identified by performing a comprehensive parametric study and sensitivity analysis. The results indicate that only 3 parameters, including the percentage of gas turbine load, ambient temperature, and ambient pressure, affect the gross output power, i.e., increasing ambient temperature from -20 to 50 oC leads to an 8% increase in efficiency of the CHP system. In contrast, moving from the highest elevation in Iran to a beach can result in a 20% reduction in the output power of the cogeneration system. This is while 8 parameters significantly affect the efficiency of the cogeneration system. For instance, changing gas turbine load from 100% to 25% leads to a 25% reduction in the efficiency of the cogeneration system. Furthermore, the correlations between important input and output parameters are presented, which can be easily used for different environmental and working conditions of cogeneration systems and are, in fact, a roadmap for the feasibility of using this type of system in various regions and working conditions. [ABSTRACT FROM AUTHOR]

Metal matrix composites (MMC) introduced special features such as resistance to wear and high strength to weight ratio and these characteristics categorized them as difficult-to-cut materials in the field of machining. In the current paper, a novel study on the cutting fluid emulsion 5% role in the machinability of a magnesium-based metal matrix composite reinforced by silicon carbide (SiC) particles is presented. AZ91 magnesium alloy, with nominal composition Mg-9Al-1Zn, composites were made using stir casting method. Then, the composite samples were machined and the cutting parameters such as cutting speed, feed rate and side cutting edge angle were varied to assess their effects on the wear and surface roughness. To measure and analyze the wear, optical and scanning electron microscope (SEM) were used. Also, elemental analysis through energy-dispersive X-ray spectroscopy (EDS) was accomplished. Surface roughness of machined samples were measured by a profilometer and 3D surface topography. Results of SEM and EDS images indicated that SiC particles included in the composites act as grinders and remove the surface of tool even in a short time because of the severe abrasion. Additionally, surface of machined MMCs contains some defects such as cracks, broken SiC, and unwanted deformations. Using cutting fluid emulsion 5% enhanced the tool life as well as the surface quality remarkably for different cutting speeds, feed rates and cutting edge angles although finished surface of the samples were oxidized. Also, the cutting fluid considerably reduced the amount of adhered materials on the flank face. [ABSTRACT FROM AUTHOR]

The fused deposition modeling (FDM) technique is widely used in different industries due to its low cost and ability to produce complex geometries from polymers. In this technique, some manufacturing parameters are essential because of their effects on the mechanical performance of the final fabricated part. The current study investigated the impact of path strategy and printing speed, two key manufacturing factors, on the mechanical performance of printed disks. Six types of path strategies of rasters corresponding to the loading direction, namely unidirectional-vertical, unidirectional-horizontal, unidirectional-45, cross, cross-45, and concentrate, were used for printing some disks, and compressive tests were done on them. The results showed that these path strategies' average compressive failure loads were 2955, 4957, 2342, 4640, 3971, and 5893 N, respectively. The lower compressive strength of the unidirectional path pattern was due to the weak zones that were located between the printed layers and rasters. Besides, three printing speeds of 40, 60, and 80 mm/s were considered to fabricate the disks with a concentrate path pattern, and compressive experiments were performed. The results showed that the 40 mm/s printing speed conducted a compressive failure load of 4544 N, while 60 and 80 mm/s resulted in 3008 and 2828 N, respectively. Finally, inter-layer strength as a major factor in controlling the compressive strength of the disks was comprehensively discussed. [ABSTRACT FROM AUTHOR]

Background: Various factors, including family associations, school culture, personality traits, and lifestyle play a fundamental role in the development of drug addiction. This study aimed to investigate how the association of family communication patterns and school culture affect addiction tendencies among high school students in Yazd, Iran. Methods: This cross-sectional study was conducted in January 2021. A total number of 420 people were selected using the random multi-stage sampling method. To collect data, addiction tendency scale, family communication pattern and school culture questionnaires were used. Data analysis was done using SPSS version 24, Pearson's correlation coefficient, descriptive statistics, T-Tests and ANOVA. Results: The mean±SD for addiction tendency, family communication patterns and school culture was 40.24±7.65, 65.84±5.34, and 45.69±9.24, respectively. This study showed a statistically significant association between the mean score for addiction tendency and gender (P=0.01) and economic status (P=0.02). Among the two components of communication patterns, alignment orientation (R=-0.31, P<0.001) showed a negative association and conformity orientation (R=0.25, P=0.01) showed a significant positive association with addiction tendency. Additionally, all of the three components of school culture, namely, student relations (R=-0.23, P=0.02), student and teacher associations (R=-0.29, P<0.001), and training opportunities (R=-0.20, P=0.03) revealed a significant negative association with addiction tendencies. Conclusion: According to the results of the study, it is recommended to implement family education programs in counseling centers, health centers and schools. These programs should emphasize the importance of creating a healthy communication pattern based on dialogue and active listening in the family. By promoting positive personality traits, young people can effectively combat their inclination towards drug use and decrease the chances of developing addiction. [ABSTRACT FROM AUTHOR]

Machining of metal matrix composites (MMC) are being increasingly taken into consideration due to MMCs' especial features like high strength to weight ratio, resistance to wear and creep. In this paper, effects of cutting parameters on the surface quality, tool life, and cutting force when machining of AZ91/SiC composites are analyzed to make the process optimized. To this end, a design of experiment based on the response surface methodology are done to consider variations of cutting parameters such as cutting speed, feed rate, and depth of cut. Challenges like particles pulled out and tool worn out in the machining process are evaluated. Subsequently, the results of cutting responses are analyzed and a multi-objective optimization is applied on the data to obtain the best surface quality, the highest production volume and the condition at which tool life is longest. The results showed although increasing the feed rate from 0.05 to 0.1mm/rev leads to the tool life reduction about 70%, it enhances the productivity considerably about 100% for composites with volume fraction 5%. Moreover, at cutting speed 41.05 m/min and feed rate 0.07mm/rev, machining process of AZ91/SiC-vol.5% becomes efficient. [ABSTRACT FROM AUTHOR]

A considerable residual stress distribution can be produced while bending of parts. This stress distribution depends on material behavior. In this article, residual stress distribution has been determined through the thickness in beam bending. For three different models of elastic–plastic behavior, the stress distribution and maximum residual stress are derived analytically. The residual stress is compared for three different bending radii as a case study. Also, finite element analysis has been carried out for two material properties. The results show that material behavior has little effect on stress distribution for large value of bending radius. As the bending radius decreases, difference of stress distribution increases rapidly among three plastic behaviors. Comparing the results of finite element and analytical stress distribution shows good accuracy for suggested formulations. [ABSTRACT FROM AUTHOR]

Aspirin is one of the certified medicines commonly used for the secondary prevention of myocardial infarction (MI). Aspirin side effects and gastrointestinal bleeding, in particular, have arisen debates on its use for the primary prevention of MI. The present research evaluates the cost-effectiveness of the use of aspirin in the primary prevention of MI among Iranian men with average cardiovascular disease (CVD) risk, using Markov modeling technique. The incremental cost-effectiveness ratios (ICERs) estimated to be 864 USA dollars (USD) per quality-adjusted life years (QALY) gained and 782 USD per life years gained (LYG) for each patient in the base-case scenario (public tariffs and no discounting). This research proves costeffectiveness of the use of aspirin in the primary prevention of MI in targeted population, since the assessed ICERs are quite under the recommended threshold by WHO which is one gross domestic product (GDP) per capita ($5315.1 for Iran in 2015). [ABSTRACT FROM AUTHOR]

In this research the designed mechanism for chasing and repoussé of sheet metal is studied. This mechanism is similar to incremental sheet metal forming. In this kind of sheet metal forming, sheet surrounding is fixed and forming tool pastes the desired pattern on sheet metal incrementally. The major differences between designed mechanism and traditional incremental forming are as follows: control on the punch energy and sequence, and fixing the sheet by using protectant material behind it instead of clamping sheet sides. In this mechanism, the solenoid is used as a hammer. The plunger moves to the center of the coil while energized. Striking energy could be controlled by controlling the excitement voltage and punching sequence could be adjusted by manipulating the excitement algorithm. In this paper, the utilized solenoid is simulated. The mechanical and magnetic relations are merged for this. Flexible mesh is used to make it possible for the plunger to have movement. An experimental setup is executed to measure force on the plunger during stroke, this is used for validation. Plunger head is one important parameter affecting strike energy, thus an appropriate plunger head angle is investigated. Plunger mass is changeable, so this parameter is considered and drilled plunger is simulated. Finally, the effect of coil cover on strike energy and power is studied. [ABSTRACT FROM AUTHOR]

New trends have been observed in recent years for rapid prototyping of sheet metal parts by Incremental Forming process, particularly in low quantity production. Recent ideas have been presented for a new type of this process known as Incremental sheet metal hammering (ISMH) method. In ISMH process, by sequence moving of a hammering punch over a clamped sheet metal, a three-dimensional work piece is produced without using a die. In this paper, the effect of tool parameter on the formability of Al-1100 will be studied. To investigate this issue, the sheet is clamped. Then by considering the cone angle, hammering is applied at a certain diameter and frequency until the failure occurs. By recording the angle and the height values at failure point, a correlation has been extracted between the diameter and the frequency. Analysis of the results shows that by decreasing the diameter of the punch, maximum strain in the direction of thickness is observed at higher height. Also, by increasing the diameter of the punch, formability of Al-1100 increases. Moreover, it is shown that by increasing the impact frequency, the formability of the sheet will be decreased. [ABSTRACT FROM AUTHOR]