Introduction/purpose: The frequency hopping spread spectrum (FH-SS) technique assumes the carrier generated by the syntesizer to hop from frequency to frequency over a wide bandwidth, according to a pseudonoise code sequence defined by the code sequence generator. The article presents the history, principles and applications of the FH-SS technique. Both military and commercial applications are discussed. Methods: This article presents an overview of data from the technical literature, with appropriate comments. Results: After presenting the history and principles of the FH-SS technique, the article summarizes its use with examples of military and commercial applications. The importance of using FH-SS in the described applications is highlighted. Conclusion: The FH-SS technique has been successfully implemented in many military and commercial technologies due to its high protection against interference, making communication difficult for reconnaissance and eavesdropping, and its ability to provide code division multiple access.
{"title":"Frequency hopping spread spectrum: History, principles and applications","authors":"V. Ristić, B. Todorović, N. Stojanović","doi":"10.5937/vojtehg70-38342","DOIUrl":"https://doi.org/10.5937/vojtehg70-38342","url":null,"abstract":"Introduction/purpose: The frequency hopping spread spectrum (FH-SS) technique assumes the carrier generated by the syntesizer to hop from frequency to frequency over a wide bandwidth, according to a pseudonoise code sequence defined by the code sequence generator. The article presents the history, principles and applications of the FH-SS technique. Both military and commercial applications are discussed. Methods: This article presents an overview of data from the technical literature, with appropriate comments. Results: After presenting the history and principles of the FH-SS technique, the article summarizes its use with examples of military and commercial applications. The importance of using FH-SS in the described applications is highlighted. Conclusion: The FH-SS technique has been successfully implemented in many military and commercial technologies due to its high protection against interference, making communication difficult for reconnaissance and eavesdropping, and its ability to provide code division multiple access.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84329486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction/purpose: The article presents a model of a slow frequency hopping radio in the case of repeater jamming. The aim is to analyze the effectiveness of repeater jamming to a military tactical slow frequency hopping radio. Methods: It is assumed that the repeater jammer will be successful in detecting signals with slow frequency hopping at each hop and that it will perform successful partial jamming of the intercepted communication. Under partial jamming, it is considered that a certain part of the transmission time of each hop will be jammed. A theoretical analysis of the impact of a repeater jammer on a frequency hopping radio was performed based on the definition of the total probability of error. Various parameters that affect the segment of hop duration under jamming were considered. Results: The obtained results show that high effective jamming is achieved even when a short segment of hop duration is jammed. We discuss the conditions for the repeater jammer to detect the signal during each hop and emit the jamming signal with the required strength. It has been shown that increasing the frequency hopping rate can significantly reduce the effectiveness of the repeater jammer. Conclusion: Repeater jammers are highly effective against slow frequency hopping radio communication systems.
{"title":"Analysis of repeater jamming of a slow frequency hopping radio","authors":"Nenad Stojanović, B. Todorović, V. Ristić","doi":"10.5937/vojtehg70-37535","DOIUrl":"https://doi.org/10.5937/vojtehg70-37535","url":null,"abstract":"Introduction/purpose: The article presents a model of a slow frequency hopping radio in the case of repeater jamming. The aim is to analyze the effectiveness of repeater jamming to a military tactical slow frequency hopping radio. Methods: It is assumed that the repeater jammer will be successful in detecting signals with slow frequency hopping at each hop and that it will perform successful partial jamming of the intercepted communication. Under partial jamming, it is considered that a certain part of the transmission time of each hop will be jammed. A theoretical analysis of the impact of a repeater jammer on a frequency hopping radio was performed based on the definition of the total probability of error. Various parameters that affect the segment of hop duration under jamming were considered. Results: The obtained results show that high effective jamming is achieved even when a short segment of hop duration is jammed. We discuss the conditions for the repeater jammer to detect the signal during each hop and emit the jamming signal with the required strength. It has been shown that increasing the frequency hopping rate can significantly reduce the effectiveness of the repeater jammer. Conclusion: Repeater jammers are highly effective against slow frequency hopping radio communication systems.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72517754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction/purpose: The aim of this article is to establish integral transforms of the generalized Lommel-Wright function. Methods: These transforms are expressed in terms of the Wright Hypergeometric function. Results: Integrals involving the trigonometric, generalized Bessel function and the Struve functions are obtained. Conclusions: Various interesting transforms as the consequence of this method are obtained.
{"title":"A study on integral transforms of the generalized Lommel-Wright function","authors":"K. Saeed, Sirazul Haq, Khan Ali, N. Fabiano","doi":"10.5937/vojtehg70-36402","DOIUrl":"https://doi.org/10.5937/vojtehg70-36402","url":null,"abstract":"Introduction/purpose: The aim of this article is to establish integral transforms of the generalized Lommel-Wright function. Methods: These transforms are expressed in terms of the Wright Hypergeometric function. Results: Integrals involving the trigonometric, generalized Bessel function and the Struve functions are obtained. Conclusions: Various interesting transforms as the consequence of this method are obtained.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74915877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Modern weapons and military equipment","authors":"D. Vučković","doi":"10.5937/vtg2202491v","DOIUrl":"https://doi.org/10.5937/vtg2202491v","url":null,"abstract":"","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90758903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Milena Grdović, D. Protić, Vlada Antić, Boriša Jovanović
Introduction/purpose: The security of systems can be jeopardized by compromising emanations. This paper provides an overview of computer screen attacks. New technologies can be used to exfiltrate sensitive data from computer screens. Emission security is the prevention of electromagnetic signal attacks that are conducted or radiated. Methods: This paper examines the impact of a side-channel attack that intercepts compromised information from a computer screen. The leakage of electromagnetic data is also explained. Software-defined radios are described to explain malicious attacks on computer monitors. Results: The source of the electromagnetic signal determines the nature of the side-channel information they carry. The most well-known issue associated with revealing emissions is the possibility of intercepting visual information displayed on computer monitors. Conclusion: Visual data displayed on computer monitors could be intercepted by a software-defined radio which can digitize the desired frequency spectrum directly from an antenna, present it to a digital signal processor, and output it to an application for revealing sensitive data. A Grdović, M. et al, Screen reading: electromagnetic information leakage from the computer monitor, pp.836-855 variety of countermeasures, such as shielding, zoning, soft TEMPEST, and similar techniques, can be used to prevent data leakage.
{"title":"Screen reading: Electromagnetic information leakage from the computer monitor","authors":"Milena Grdović, D. Protić, Vlada Antić, Boriša Jovanović","doi":"10.5937/vojtehg70-38930","DOIUrl":"https://doi.org/10.5937/vojtehg70-38930","url":null,"abstract":"Introduction/purpose: The security of systems can be jeopardized by compromising emanations. This paper provides an overview of computer screen attacks. New technologies can be used to exfiltrate sensitive data from computer screens. Emission security is the prevention of electromagnetic signal attacks that are conducted or radiated. Methods: This paper examines the impact of a side-channel attack that intercepts compromised information from a computer screen. The leakage of electromagnetic data is also explained. Software-defined radios are described to explain malicious attacks on computer monitors. Results: The source of the electromagnetic signal determines the nature of the side-channel information they carry. The most well-known issue associated with revealing emissions is the possibility of intercepting visual information displayed on computer monitors. Conclusion: Visual data displayed on computer monitors could be intercepted by a software-defined radio which can digitize the desired frequency spectrum directly from an antenna, present it to a digital signal processor, and output it to an application for revealing sensitive data. A Grdović, M. et al, Screen reading: electromagnetic information leakage from the computer monitor, pp.836-855 variety of countermeasures, such as shielding, zoning, soft TEMPEST, and similar techniques, can be used to prevent data leakage.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90194149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction/purpose: The newly developed probability-based multi - objective optimization (MOO) has introduced a novel concept of preferable probability to represent a preferability degree of a candidate in optimization in order to overcome the inherent shortcomings of subjective and "additive" factors in the previous MOO methods. In this paper, the new method is extended to include robust optimization for material engineering. Furthermore, energy consumption in a melting process with orthogonal array design and the robust optimization of four different process schemes in machining an electric globe valve body are taken as examples. Methods: The arithmetic mean value of each performance utility indicator of the candidate contributes to one part of the partial preferable probability, while the deviation of each performance utility indicator from its arithmetic mean value of the candidate contributes to the other part of the partial preferable probability quantitatively. Furthermore, following the procedures of the newly developed probability-based multi-objective optimization (PMOO), the total preferable probability of a candidate is obtained, which thus transfers a multi-objective optimization problem into a single objective optimization problem. Results: The optimal control factors of lower electric energy consumption with robustness are bundled steel, loose steel, and uncleaned steel of 12.5%, 50% and 37.5% by weight, respectively, in this steel melting process. This case is closely followed by the scenario of 50 wt% bundled steel, 50 wt% loose steel, and 0 wt% uncleaned steel. The robust optimization of four different process schemes for machining an electric globe valve body is scheme No. 1. Conclusion: The extension of probability-based multi-objective optimization while considering robustness is successful, which can be easily used to deal with the optimal problem with dispersion of data to get objectively an optimal result with robustness in material engineering. The extension of probability-based multi-objective optimization while considering robustness will be beneficial to relevant research and process optimization.
{"title":"An approach of probability based multi-objective optimization considering robustness for material engineering","authors":"M. Zheng, H. Teng, Yi Wang","doi":"10.5937/vojtehg70-35795","DOIUrl":"https://doi.org/10.5937/vojtehg70-35795","url":null,"abstract":"Introduction/purpose: The newly developed probability-based multi - objective optimization (MOO) has introduced a novel concept of preferable probability to represent a preferability degree of a candidate in optimization in order to overcome the inherent shortcomings of subjective and \"additive\" factors in the previous MOO methods. In this paper, the new method is extended to include robust optimization for material engineering. Furthermore, energy consumption in a melting process with orthogonal array design and the robust optimization of four different process schemes in machining an electric globe valve body are taken as examples. Methods: The arithmetic mean value of each performance utility indicator of the candidate contributes to one part of the partial preferable probability, while the deviation of each performance utility indicator from its arithmetic mean value of the candidate contributes to the other part of the partial preferable probability quantitatively. Furthermore, following the procedures of the newly developed probability-based multi-objective optimization (PMOO), the total preferable probability of a candidate is obtained, which thus transfers a multi-objective optimization problem into a single objective optimization problem. Results: The optimal control factors of lower electric energy consumption with robustness are bundled steel, loose steel, and uncleaned steel of 12.5%, 50% and 37.5% by weight, respectively, in this steel melting process. This case is closely followed by the scenario of 50 wt% bundled steel, 50 wt% loose steel, and 0 wt% uncleaned steel. The robust optimization of four different process schemes for machining an electric globe valve body is scheme No. 1. Conclusion: The extension of probability-based multi-objective optimization while considering robustness is successful, which can be easily used to deal with the optimal problem with dispersion of data to get objectively an optimal result with robustness in material engineering. The extension of probability-based multi-objective optimization while considering robustness will be beneficial to relevant research and process optimization.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90399983","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Introduction/purpose: The paper analyzes the impact of malicious codes in the cloud. Malicious code is an unauthorized piece of code that violates the integrity of an application and infrastructure to cause certain effects, such as security breaches, spread of infections, and data infiltration from the computer with the help of malicious software - this is a simple form of data theft which can lead to disastrous consequences in all segments of society, especially when it comes to national security. To overcome this challenge, it is necessary to detect holes in the safety of cloud environments and repair them before the attackers use these vulnerabilities to bypass the integrated cloud infrastructure. Methods: Structural analysis, functional analysis, comparative analysis, synthesis. Results: There are many factors for collecting, comparing, and delivering intelligence data on cloud threats. Cloud applications are increasingly being targeted because their use to store and share data with mobile application hosting has been increased exponentially, enabling industrial automation and business information monitoring and procurement. In addition, billions of devices on the Internet use the cloud infrastructure as a background for processing and transmitting large data sets. Malicious code is easily distributed due to the ease of sharing documents and files via the cloud. Conclusion: As cloud technologies are taking a central place in the world of digital transformation, the threat to the cloud environment is expected to grow exponentially. This means that organizations need to ensure that the cyber security position of the cloud infrastructure they possess is robust and mature enough to combat all relevant security threats in order to minimize business risks. Understanding the nature of practical security controls and how they are assessed enables organizations to build a practical approach to security and privacy in the cloud.
{"title":"Malicious code in the cloud","authors":"Dragan Damjanović","doi":"10.5937/vojtehg70-37168","DOIUrl":"https://doi.org/10.5937/vojtehg70-37168","url":null,"abstract":"Introduction/purpose: The paper analyzes the impact of malicious codes in the cloud. Malicious code is an unauthorized piece of code that violates the integrity of an application and infrastructure to cause certain effects, such as security breaches, spread of infections, and data infiltration from the computer with the help of malicious software - this is a simple form of data theft which can lead to disastrous consequences in all segments of society, especially when it comes to national security. To overcome this challenge, it is necessary to detect holes in the safety of cloud environments and repair them before the attackers use these vulnerabilities to bypass the integrated cloud infrastructure. Methods: Structural analysis, functional analysis, comparative analysis, synthesis. Results: There are many factors for collecting, comparing, and delivering intelligence data on cloud threats. Cloud applications are increasingly being targeted because their use to store and share data with mobile application hosting has been increased exponentially, enabling industrial automation and business information monitoring and procurement. In addition, billions of devices on the Internet use the cloud infrastructure as a background for processing and transmitting large data sets. Malicious code is easily distributed due to the ease of sharing documents and files via the cloud. Conclusion: As cloud technologies are taking a central place in the world of digital transformation, the threat to the cloud environment is expected to grow exponentially. This means that organizations need to ensure that the cyber security position of the cloud infrastructure they possess is robust and mature enough to combat all relevant security threats in order to minimize business risks. Understanding the nature of practical security controls and how they are assessed enables organizations to build a practical approach to security and privacy in the cloud.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83203464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Pešić, Aleksandra Živković, Aleksa Aničić, Lazar Blagojević, Petko Bonchev, Predrag Pantović
Introduction/purpose: The paper presents a numerical simulation of an impact of a 12.7 mm projectile on an armored metal plate with a velocity of 500 m/s at a distance of 900 m. Numerical simulations offer the possibility of drastically reducing the time required to obtain results in comparison to the time required for planning, organization and execution of experiments. The numerical simulation is done by variations in the thickness of the armor metal plate, specifically an armor metal plate of a thickness of 10 mm, 17 mm, 18 mm, and 23 mm. The mentioned armored plate thicknesses were chosen based on the results in order to determine the limit thickness of the armored plate for the projectile perforation limit, as well as for complete ballistic protection. Methods: Finite element modeling is used for analyzing stresses and deformations of the armored plates. The mentioned method calculates the impact of the projectile on the obstacle, precisely the collision of the projectile and the armor plate. Results: For the comparative analysis, the parameters used are the values of the stress and the displacement. For each of the above-mentioned thicknesses of the armored metal plate, the values of stress and displacement during projectile impact were determined. The results of this study show how the thickness of the armor plate affects the interaction of the projectile and the armor plate. Conclusion: If the physical and chemical characteristics of the armored plate remain unchanged, as the thickness of the armored plate increases, the possibility of projectile penetration decreases, and vice versa. This research is of essential importance because it analyzes the stresses and deformation of armor plates whose basic role is the protection of personnel and equipment from the projectile impact. In this regard, the thickness of the armored plate for semi-penetration of the projectile is determined.
{"title":"Numerical analysis of a frontal impact of a 12.7 mm projectile on an armor plate","authors":"M. Pešić, Aleksandra Živković, Aleksa Aničić, Lazar Blagojević, Petko Bonchev, Predrag Pantović","doi":"10.5937/vojtehg70-38412","DOIUrl":"https://doi.org/10.5937/vojtehg70-38412","url":null,"abstract":"Introduction/purpose: The paper presents a numerical simulation of an impact of a 12.7 mm projectile on an armored metal plate with a velocity of 500 m/s at a distance of 900 m. Numerical simulations offer the possibility of drastically reducing the time required to obtain results in comparison to the time required for planning, organization and execution of experiments. The numerical simulation is done by variations in the thickness of the armor metal plate, specifically an armor metal plate of a thickness of 10 mm, 17 mm, 18 mm, and 23 mm. The mentioned armored plate thicknesses were chosen based on the results in order to determine the limit thickness of the armored plate for the projectile perforation limit, as well as for complete ballistic protection. Methods: Finite element modeling is used for analyzing stresses and deformations of the armored plates. The mentioned method calculates the impact of the projectile on the obstacle, precisely the collision of the projectile and the armor plate. Results: For the comparative analysis, the parameters used are the values of the stress and the displacement. For each of the above-mentioned thicknesses of the armored metal plate, the values of stress and displacement during projectile impact were determined. The results of this study show how the thickness of the armor plate affects the interaction of the projectile and the armor plate. Conclusion: If the physical and chemical characteristics of the armored plate remain unchanged, as the thickness of the armored plate increases, the possibility of projectile penetration decreases, and vice versa. This research is of essential importance because it analyzes the stresses and deformation of armor plates whose basic role is the protection of personnel and equipment from the projectile impact. In this regard, the thickness of the armored plate for semi-penetration of the projectile is determined.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76356222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Bukvić, D. Petrović, I. Radisavljević, Saša Dimitrić
Introduction/purpose: During exploitation tests of gasoline storage tanks, cracks can form in an austenitic-ferrite welded joint, which can compromise the entire tank. Methods: In order to obtain a welded joint of satisfactory strength and durability, the paper analyzes the influence of heat input on the tensile characteristics of welded joints. In the current literature and practice, additional materials for welding the tank elements are selected according to the chemical compositions of the elements of basic materials, with the help of the Schaeffler diagram. In this paper, the characteristics of welded joints of gasoline storage tanks are examined, when the largest part of the tank is made of fine - grained microalloyed steel NIOMOL 490 K, while the roof part of the tank is made of austenitic steel. Slabs of these two materials were welded by the MIG process with additional material MIG 18/8/6, at different amounts of heat input. Conclusion: The analysis of the results obtained by tensile testing according to SRPS EN ISO 6892-1: 2020 standard concluded that the behavior of the joint as a whole depends on the properties of each individual part of the welded joint and their mutual influence. It was also concluded that the mutual influence is better if welding is performed with a lower amount of heat input, because then a lower degree of mixing of additional material with basic materials is achieved.
简介/用途:在汽油储罐开采试验中，奥氏体-铁素体焊接接头会产生裂纹，危及整个储罐。方法:为了获得令人满意的强度和耐久性焊接接头，分析了热输入对焊接接头拉伸特性的影响。在目前的文献和实践中，根据基本材料中元素的化学组成，借助舍弗勒图选择焊接罐件的附加材料。本文对汽油储罐的焊接接头特性进行了研究，当储罐的最大部分采用细晶微合金钢NIOMOL 490 K，罐顶部分采用奥氏体钢。这两种材料的板在不同的热量输入下，用MIG工艺与额外的材料MIG 18/8/6焊接。结论:根据SRPS EN ISO 6892-1: 2020标准对拉伸试验结果进行分析，得出的结论是，接头的整体行为取决于焊接接头各个单独部分的性能及其相互影响。还得出结论，如果以较低的热输入量进行焊接，则相互影响更好，因为这样可以实现较低程度的附加材料与基本材料的混合。
{"title":"Influence of heat input on the tensile properties of austenitic-ferritic welded joints","authors":"A. Bukvić, D. Petrović, I. Radisavljević, Saša Dimitrić","doi":"10.5937/vojtehg70-36252","DOIUrl":"https://doi.org/10.5937/vojtehg70-36252","url":null,"abstract":"Introduction/purpose: During exploitation tests of gasoline storage tanks, cracks can form in an austenitic-ferrite welded joint, which can compromise the entire tank. Methods: In order to obtain a welded joint of satisfactory strength and durability, the paper analyzes the influence of heat input on the tensile characteristics of welded joints. In the current literature and practice, additional materials for welding the tank elements are selected according to the chemical compositions of the elements of basic materials, with the help of the Schaeffler diagram. In this paper, the characteristics of welded joints of gasoline storage tanks are examined, when the largest part of the tank is made of fine - grained microalloyed steel NIOMOL 490 K, while the roof part of the tank is made of austenitic steel. Slabs of these two materials were welded by the MIG process with additional material MIG 18/8/6, at different amounts of heat input. Conclusion: The analysis of the results obtained by tensile testing according to SRPS EN ISO 6892-1: 2020 standard concluded that the behavior of the joint as a whole depends on the properties of each individual part of the welded joint and their mutual influence. It was also concluded that the mutual influence is better if welding is performed with a lower amount of heat input, because then a lower degree of mixing of additional material with basic materials is achieved.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74885267","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nezhad Deghan, Nikola Mirkov, Vesna Todorčević, S. Radenović
Introduction/purpose: The aim of this paper is to present the concept of b(an,bn)-hypermetric spaces. Methods: Conventional theoretical methods of functional analysis. Results: This study presents the initial results on the topic of b(an,bn)-hypermetric spaces. In the first part, we generalize an n-dimensional (n ≥ 2) hypermetric distance over an arbitrary non-empty set X. The b(an,bn)-hyperdistance function is defined in any way we like, the only constraint being the simultaneous satisfaction of the three properties, viz, non-negativity and positive-definiteness, symmetry and (an, bn)-triangle inequality. In the second part, we discuss the concept of (an, bn)-completeness, with respect to this b(an,bn)-hypermetric, and the fixed point theorem which plays an important role in applied mathematics in a variety of fields. Conclusion: With proper generalisations, it is possible to formulate well-known results of classical metric spaces to the case of b(an,bn)-hypermetric spaces.
{"title":"A different approach to b(an,bn)-hypermetric spaces","authors":"Nezhad Deghan, Nikola Mirkov, Vesna Todorčević, S. Radenović","doi":"10.5937/vojtehg70-35303","DOIUrl":"https://doi.org/10.5937/vojtehg70-35303","url":null,"abstract":"Introduction/purpose: The aim of this paper is to present the concept of b(an,bn)-hypermetric spaces. Methods: Conventional theoretical methods of functional analysis. Results: This study presents the initial results on the topic of b(an,bn)-hypermetric spaces. In the first part, we generalize an n-dimensional (n ≥ 2) hypermetric distance over an arbitrary non-empty set X. The b(an,bn)-hyperdistance function is defined in any way we like, the only constraint being the simultaneous satisfaction of the three properties, viz, non-negativity and positive-definiteness, symmetry and (an, bn)-triangle inequality. In the second part, we discuss the concept of (an, bn)-completeness, with respect to this b(an,bn)-hypermetric, and the fixed point theorem which plays an important role in applied mathematics in a variety of fields. Conclusion: With proper generalisations, it is possible to formulate well-known results of classical metric spaces to the case of b(an,bn)-hypermetric spaces.","PeriodicalId":30576,"journal":{"name":"Vojnotehnicki Glasnik","volume":"58 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80155604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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