Optimization of mechanical (Swage) autofrettage process

WOS: 000468368400022Autofrettage is the process of residual stress formation on the walls of the thick walled cylinders before their usage. These residual stresses help to increase the pressure bearing capacity of the thick walled cylinders by eliminating some stresses when service pressure is applied in the high pressure applications. In practice, there are two different autofrettage methods as hydraulic and swage. Swage autofrettage is a more economical method to form beneficial residual stresses in the thick walled cylinders when it is compared with the hydraulic autofrettage method. In the current study, swage autofrettage process, applied on to two thick walled cylinders which have gained different material properties by heat treatment process is investigated. The main objective of the study is to determine the optimum mandrel-inner diameter interference ratios that results in maximum benefit. In accordance with this purpose, it is determined equivalent stresses on elastic-plastic junction, which is the most critical region of autofrettaged cylinder, being assumed to be used in max. 400 MPa service pressure. At first, maximum Tresca and Von Mises equivalent stresses on the elastic-plastic junction are obtained analytically for the autofrettaged thick walled cylinders exposing to the internal pressure of 400 MPa. Then, the verification of the analytical model is performed by making use of a ABAQUS software which uses the finite element method. Swage autofrettage is applied in the factory considering optimum values and permanent expansion of inner and outer diameter is measured. It is also calculated making use of ABAQUS software and results are compared

Experimentally flight performances comparison of octocopter, decacopter and dodecacopter using universal UAV

This study presents a comparative analysis of different unmanned aerial vehicle (UAV) configurations using a proposed universal UAV. The octocopter, decacopter, and dodecacopter were experimentally evaluated through point tracking flight performances and vibration level analyses. To the best of our knowledge, this is the first study to conduct a comparative analysis of these configurations on the same platform. Our findings indicate that the dodecacopter exhibited the best overall performance, whereas the decacopter showed the lowest roll angle error. Notably, the implemented decacopter exhibited the highest pitch angle error and north position error due to its asymmetric rotor placement in the pitch axis. We observed that the octocopter demonstrated the best vibrationless flight performance, while increasing vibration magnitude was observed with an increase in the number of rotors

<p>Experimental comparison of the effect of the number of redundant rotors on the fault tolerance performance for the proposed multilayer UAV & nbsp;</p>

In this paper, experimental investigation of the flight performance of the proposed universal Unmanned Aerial Vehicle (UAV) in case of rotor failures is presented. In the experimental flight tests, proposed universal UAV that can be converted to many different configurations due to its non-standard multi layer structure was used in two different configurations as a standard octorotor and a multi-layer dodecarotor. Multiple outdoor experiments are conducted to show flight safety and reliability of the proposed UAV in terms of rotor failure tolerance. In order to evaluate flight safety and reliability of the proposed UAV, take-off, hovering and landing flight performance analyzes were performed in cases where one or two motors/propellers were completely lost. As performance criteria, errors in the UAV's roll, pitch and yaw angles, altitude error and vibration in three axes were determined. The flight test results are presented both numerically and graphically. According to the results, multi-layer dodecarotor type has shown a more stable flight performance in terms of angular position errors. In addition, in both types of UAVs, in the case of failure of two rotors rotating in the opposite direction, it has been observed that the error in yaw angle is less than a rotor failure, as expected. Likewise, in the case of failure of two rotors rotating in the same direction, performance loss was observed in the control of yaw angle. (C) 2021 Published by Elsevier B.V

The Analysis of the Effects of Olfactive Stimulus in Learning in Context of Educational Technology

13th International Educational Technology Conference -- OCT 30-NOV 01, 2014 -- Lisbon, PORTUGALWOS: 000360920300116When the educational Technologies, which are used in the process of learning-teaching process, are associated with sensory organs, the least used one becomes the olfactive stimuli. Nowadays, because of being foreground of visual-audio Technologies, Positivism is based on vision and audition but it ignores the other senses. Although seeing and hearing play important roles, the ineffectiveness of other senses is delusion in this process. In this delusion the impact of visual-audio Technologic devices from telescope to television, internet, mobile phones is inevitable. However sensation and learning is wholistic and based on togetherness of five senses. Thus, with the delusion olfactive stimulus which is rejected from the educational field is effective on senses, attention, concentration and memory in learning. The purpose of this study, which is in form literature review, is to discuss the nature of olfactive stimulus the effectiveness in education, areas of usage in context of educational technology, to deduce and to make suggestions. (C) 2013 The Authors. Published by Elsevier Ltd

Kynurenine, Kynurenic Acid, Quinolinic Acid and Interleukin-6 Levels in the Serum of Patients with Autism Spectrum Disorder

Background and Objectives: It is known that inflammatory processes play a role in the pathogenesis of autism spectrum disorder (ASD). It is also reported that immune activation induces the kynurenine pathway (KP), as known as the tryptophan destruction pathway. In our study, we aimed to investigate whether the serum levels of KP products and interleukin (IL)-6 activating indolamine 2–3 dioxygenase (IDO) enzyme are different in healthy developing children and children with ASD. Materials and Methods: Forty-three ASD children aged 2–9 were included in this study. Forty-two healthy developing children, similar to the patient group in terms of age and gender, were selected as the control group. Serum levels of kynurenic acid, kynurenine, quinolinic acid and IL-6 were analyzed using the ELISA method. ASD severity was evaluated with the Autism Behavior Checklist (ABC). Results: The mean age of children with ASD was 42.4 ± 20.5 months, and that of healthy controls was 48.1 ± 15.8 months. While the serum levels of kynurenic acid, kynurenine and interleukin-6 were higher in the group with ASD (p p > 0.05) in terms of the quinolinic acid level. There was no significant difference between the ABC total and subscale scores of children with ASD and biochemical parameters (p > 0.05). Conclusions: We conclude that these biomarkers must be measured in all ASD cases. They may be important for the diagnosis of ASD

Review of a challenging clinical issue: Intrahepatic cholestasis of pregnancy

Intrahepatic cholestasis of pregnancy (ICP) is a reversible pregnancy-specific cholestatic condition characterized by pruritus, elevated liver enzymes, and increased serum bile acids. It commences usually in the late second or third trimester, and quickly resolves after delivery. The incidence is higher in South American and Scandinavian countries (9.2%-15.6% and 1.5%, respectively) than in Europe (0.1%-0.2%). The etiology is multifactorial where genetic, endocrine, and environmental factors interact. Maternal outcome is usually benign, whereas fetal complications such as preterm labor, meconium staining, fetal distress, and sudden intrauterine fetal demise not infrequently lead to considerable perinatal morbidity and mortality. Ursodeoxycholic acid is shown to be the most efficient therapeutic agent with proven safety and efficacy. Management of ICP consists of careful monitoring of maternal hepatic function tests and serum bile acid levels in addition to the assessment of fetal well-being and timely delivery after completion of fetal pulmonary maturity. This review focuses on the current concepts about ICP based on recent literature data and presents an update regarding the diagnosis and management of this challenging issue