Safety and reliability are primary concerns in launch vehicle performance due to the involved costs and risk. Pressure vessels are one of the significant subsystems of launch vehicles. In order to have minimal weight, high strength material viz. maraging steel M250 grade is used in realizing the pressure vessel casing hardware. Despite the best efforts in design methodology, quality evaluation in production and effective structural integrity assessment is still a farfetched goal. The evolution of such a system requires, first, identification of an appropriate technique and next its adoption to meet the challenges posed by advanced materials like maraging steels. In fact, a quick survey of the available Non-Destructive Evaluation (NDE) techniques suggests Acoustic Emission (AE) as an effective structural integrity assessment tool capable of identifying any impending failure or degradation at an earlier stage. Experience shows that the longitudinal welds in the pressure vessels are quite vulnerable to failure due to the fact that they experience the maximum stress (i.e. hoop stress). Loading welded tensile samples are quite synonymous to the hoop stress experienced by longitudinal welds. An attempt is made to compare the Acoustic Emission data acquired during tensile deformation of maraging steel welded specimens. A total of 16 welded specimen’s with known defects were studied for their tensile behaviour is in connection with Acoustic Emission data. The lowest failure load was 70.5 kN and the highest being 84.8 kN. AE activity graphs viz. cumulative AE activity, hit rate, energy rate, count rate, AE amplitude history, AE count history, AE energy history, amplitude-count correlation and hit amplitude distribution have been investigated and salient features with respect to the data have been critically studied and relevant correlations are arrived at.

The paper presents the susceptibility of AE44 magnesium alloy to electrochemical corrosion and stress corrosion cracking (SCC). The evaluation of the intensity of the interaction of the corrosive environment was carried out using the corrosion tests and the Slow Strain Rate Test (SSRT). Corrosion tests performed in 0.1 M Na2SO4 solution (immersion in solution and under cathodic polarization conditions) revealed that the layer of corrosion products was much thicker after immersion test. The results of SSRT showed that the AE44 alloy deformed in the solution was characterized by higher plasticity compared to the alloy deformed in the air after immersion in solution. Moreover, the fractures were characterized by different morphology. In the case of an alloy deformed in the solution under cathodic polarization many microcracks on the fracture were observed, which were not observed in the case of the alloy deformed in the air.

Metal network compounds have primary properties. The use of lightweight and low vitality is a testament to the growing interest in the automotive industry. Aluminum alloys, due to their advanced physical, mechanical and tribological properties, have become a highly emerging material for a variety of industrial applications and the importance of efficient material selection is explained. In this paper, an Al8011 hybrid metal matrix composite is developed through the stir casting process. The different weight proportions of B ₄C (3%, 6%, 9% & 12%) and fixed proportions of 2% MoS2 have been used. Composite developed are subjected to mechanical properties evaluation and seawater corrosion studies following standard procedures. To study the porosity of the composite samples, theoretical density and actual density are calculated. An acoustic emission system-assisted tensile test is carried out to report the strength of the composite. From this experimental method, adding reinforcement can increase the tensile strength and hardness of the composites. Under sea water, the increase in reinforcement found an increase in corrosion resistance. Fractured surfaces were perused using SEM and EDS analysis.

Nowadays, information security management systems are important parts of managing a system for better handling of the information security. In scenarios and situations where safety management is done by managing protection of malwares, it is important to manage security issues properly. Cryptography is an approach which makes possible for a recipient to encrypt and decrypt the information. A combination of two different strategies for encryption and decryption in the text encoding will be transformed into the used all content. The encryption and decryption key of the content decryption key is used. There are different types of information. A number, such as finding two large prime numbers with that product. The number, the size of the RSA key is large enough to make, it's hard to pinpoint these numbers. The key, known as the RSA public key, is the most prominent open encryption. Calculations were used for information exchange. In this paper, we created a program for simulation and testing of apply cryptography of Advance Encryption Standard (AES) algorithm with Rivest-Shamir-Adleman (RSA) algorithm for better performance. In this study, this program is an application of a new algorithm to be the AES&RSA principle of using a public key instead of a private key for cryptography, and the testing of encryption and decryption for the AES&RSA algorithm resulted in time is no different on the AES algorithm and more secure encryption and decryption. The results indicated that the time needed for encoding and decoding of AES&RSA algorithm has been reduced (i.e., efficiency has been improved).

The results of the Charpy impact test of AE-type magnesium alloys produced by the high pressure die casting method are presented. Three alloys with different weight fractions of rare earth elements (RE; e.g. 1, 3 and 5 wt%) and the same mass fraction of aluminium (5 wt%) were prepared. The casts were fabricated using a typical cold chamber high pressure die casting machine with a 3.8 MN locking force. Microstructural analyses were performed by means of a scanning electron microscope (SEM). The impact strength (IS) was determined using a Charpy V hammer with an impact energy equal to 150 J. The microstructure of the experimental alloys consisted of an -Mg solid solution and Al11RE3, Al10Ce2Mn7 and Al2RE intermetallic compounds. The obtained results show the significant influence of the rare earth elements to aluminium ratio on the impact strength of the investigated materials. Lower the RE/Al ratio in the chemical composition of the alloy results in a higher impact strength of the material.

The methods arc described for determinations of Al, Fe, Ca, Mg, Ba, Cr, Mn, Ni, Cu, Zn, Pb, Cd, V and Sr in botanical, coal fly ash and soil samples by flame atomic absorption spectrometry (FAAS), and inductively coupled plasma atomic emission spectrometry (!CP-AES). Special attention has been paid to sample preparation, an important stage at which a sample is explored to contaminants. Results of the analysis of all samples arc discussed.

This article describes security mechanisms used by 3rd-7th layers in OSI/ISO network model. Many of commonly used protocols by these layers were designed with assumption that there are nointruders. Such assumption was true many years ago. The network situation has been changed for last few years and we should realize that some properties of existing protocols may be abused. Moreover, we should exchange some of them or create new versions. There are some methods and guidelines concerning secure programming, but there is also lack of guidelines about creating secure protocols. Authors see the necessity of such guideline and this article is an attempt at analysing existing solutions and selecting some universal and important patterns.