P Ivan Pokrajac, Miodrag S. Vračar, Tamara Šević, Vasilija J. Joksimović
The localization of various acoustic sources in a battlefield (such as weapon rounds, mortars, rockets, mines, improvised explosive devices, vehicle-borne improvised explosive devices and airborne vehicles) nowadays has a significant history. In acoustic source localization systems of multiple sensors, networked and placed at known positions are used to detect signals emitted from the source and perform localization of the source. Time of arrival estimation of the gun fire shock waves at large distances is significant when the purpose is the gun localization. At large distances shock wave signal is significantly deformed and therefore it is relatively difficult to accurately estimate the time of arrival. In this paper methods for TOA estimation are proposed, which are based on cumulants of the acoustic signal which originate from distant gunfire events. Localization of acoustic sources is performed in two steps by time difference estimation of acoustic signal arrival and using Discrete Probability Density method for positioning. Numerous field experiments have been conducted in order to verify performance of the proposed approach.
{"title":"Position determination of acoustic source using higher-order spectral analysis for time of arrival estimation","authors":"P Ivan Pokrajac, Miodrag S. Vračar, Tamara Šević, Vasilija J. Joksimović","doi":"10.5937/str1903041p","DOIUrl":"https://doi.org/10.5937/str1903041p","url":null,"abstract":"The localization of various acoustic sources in a battlefield (such as weapon rounds, mortars, rockets, mines, improvised explosive devices, vehicle-borne improvised explosive devices and airborne vehicles) nowadays has a significant history. In acoustic source localization systems of multiple sensors, networked and placed at known positions are used to detect signals emitted from the source and perform localization of the source. Time of arrival estimation of the gun fire shock waves at large distances is significant when the purpose is the gun localization. At large distances shock wave signal is significantly deformed and therefore it is relatively difficult to accurately estimate the time of arrival. In this paper methods for TOA estimation are proposed, which are based on cumulants of the acoustic signal which originate from distant gunfire events. Localization of acoustic sources is performed in two steps by time difference estimation of acoustic signal arrival and using Discrete Probability Density method for positioning. Numerous field experiments have been conducted in order to verify performance of the proposed approach.","PeriodicalId":33842,"journal":{"name":"Scientific Technical Review","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71084875","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}
Vladan J. Anićijević, T. Lazarević-Pašti, D. Vasić-Anićijević, Radovan Karkalić
Esters of organophosphorus acids (OPs) are widely used nowadays. They have an application as pesticides, drugs or chemical warfare agents. Their acute toxicity is ascribed to the inhibition of acetylcholinesterase (AChE), a key enzyme in the transmission of nerve impulses in mammals. Their toxic effects are manifested by the accumulation of acetylcholine and can lead to the paralysis or death. OPs poisoning therapy is based on the application of specific antidotes as well as non-specific and symptomatic procedures. In this contribution, recent achievements concerning the protection from OPs activity and an overview of the methods for their removal from the environment and decontamination of contaminated persons were presented
{"title":"Esters of organophosphorus acids: Toxicity, application and removal from the environment","authors":"Vladan J. Anićijević, T. Lazarević-Pašti, D. Vasić-Anićijević, Radovan Karkalić","doi":"10.5937/str1903015a","DOIUrl":"https://doi.org/10.5937/str1903015a","url":null,"abstract":"Esters of organophosphorus acids (OPs) are widely used nowadays. They have an application as pesticides, drugs or chemical warfare agents. Their acute toxicity is ascribed to the inhibition of acetylcholinesterase (AChE), a key enzyme in the transmission of nerve impulses in mammals. Their toxic effects are manifested by the accumulation of acetylcholine and can lead to the paralysis or death. OPs poisoning therapy is based on the application of specific antidotes as well as non-specific and symptomatic procedures. In this contribution, recent achievements concerning the protection from OPs activity and an overview of the methods for their removal from the environment and decontamination of contaminated persons were presented","PeriodicalId":33842,"journal":{"name":"Scientific Technical Review","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71085014","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}
This work examines the effect of imperfections on fatigue crack growth (FCG) in lap joints (Hi-Lok fasteners). The Finite Element Method (FEM) is used to model the cold-working and interference fit processes. FE predictions are shown to be consistent with experimental and computational results in the literature. The Extended Finite Element Method (XFEM) is then used to simulate a Mode I through crack in a rectangular plate starting at the fastener hole subjected to cold-working and interference fit. Four constant load ratio fatigue cases are investigated: (i) no residual stress, no imperfection, (ii) no residual stress, imperfection, (iii) residual stress, no imperfection and (iv) residual stress, imperfection. XFEM predictions used with the Walker equation predict that the presence of an axial gouge within a hole may result in a significant decrease (23%) in the component fatigue life under constant amplitude cyclical loading. This decrease appears to be exacerbated if a residual compressive stress field due to cold-work and interference fit is present
{"title":"The effect of imperfections on crack growth rates in cold worked and interference fit holes","authors":"C. Coates, Ved S Vakharia","doi":"10.5937/str1903035c","DOIUrl":"https://doi.org/10.5937/str1903035c","url":null,"abstract":"This work examines the effect of imperfections on fatigue crack growth (FCG) in lap joints (Hi-Lok fasteners). The Finite Element Method (FEM) is used to model the cold-working and interference fit processes. FE predictions are shown to be consistent with experimental and computational results in the literature. The Extended Finite Element Method (XFEM) is then used to simulate a Mode I through crack in a rectangular plate starting at the fastener hole subjected to cold-working and interference fit. Four constant load ratio fatigue cases are investigated: (i) no residual stress, no imperfection, (ii) no residual stress, imperfection, (iii) residual stress, no imperfection and (iv) residual stress, imperfection. XFEM predictions used with the Walker equation predict that the presence of an axial gouge within a hole may result in a significant decrease (23%) in the component fatigue life under constant amplitude cyclical loading. This decrease appears to be exacerbated if a residual compressive stress field due to cold-work and interference fit is present","PeriodicalId":33842,"journal":{"name":"Scientific Technical Review","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71085032","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}
This paper studies the closed-loop control of an electromagnetic vibratory feeder (EVF). Two different linear design procedures have been employed: a conventional proportional-integral-derivative (PID) controller, and a model predictive control (MPC) controller. All derived results have been validated by computer simulation of a nonlinear mathematical model of the system. The results have proved that both controllers achieve a good tracking of the desired output in a selected operating point. In comparison to the PID controller, the MPC controller is more sensitive to disturbances in the form of changes in the mass of material being transported
{"title":"System approach to bulk material flow control on an electromagnetic vibratory feeder","authors":"Petar J. Mišljen, Z. Despotovic, M. Matijevic","doi":"10.5937/str1902003m","DOIUrl":"https://doi.org/10.5937/str1902003m","url":null,"abstract":"This paper studies the closed-loop control of an electromagnetic vibratory feeder (EVF). Two different linear design procedures have been employed: a conventional proportional-integral-derivative (PID) controller, and a model predictive control (MPC) controller. All derived results have been validated by computer simulation of a nonlinear mathematical model of the system. The results have proved that both controllers achieve a good tracking of the desired output in a selected operating point. In comparison to the PID controller, the MPC controller is more sensitive to disturbances in the form of changes in the mass of material being transported","PeriodicalId":33842,"journal":{"name":"Scientific Technical Review","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71084933","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}
Over the last few decades, the accuracy requirements for wind tunnel testing have become much more stringent as aircraft industry strives to achieve the best performance of their products. Investments in advanced capabilities are necessary to obtain more accurate test results more efficiently, ensuring that the wind tunnels stay productive well into the future. The VTI Belgrade T-38 wind tunnel responded to these challenges by applying a hierarchical approach to design a distributed multilevel control system, a part of which is the variable-geometry nozzle positioning system, presented in this paper. It follows the hierarchy of the entire wind tunnel control system, with critical positioning loops at the field-programmable gate array (FPGA), and the user interface with real-time data analysis capability implemented on a central wind tunnel computer. In addition to more accurate positioning, the FPGA-based control system significantly improved overall operation efficiency, speed and reliability. Since the nozzle geometry uniquely determines supersonic Mach number, the improved positioning accuracy is verified in wind tunnel tests
{"title":"FPGA-based embedded system for wind tunnel variable-geometry nozzle positioning","authors":"B. Ilic, Mirko Milosavljević","doi":"10.5937/STR1901003I","DOIUrl":"https://doi.org/10.5937/STR1901003I","url":null,"abstract":"Over the last few decades, the accuracy requirements for wind tunnel testing have become much more stringent as aircraft industry strives to achieve the best performance of their products. Investments in advanced capabilities are necessary to obtain more accurate test results more efficiently, ensuring that the wind tunnels stay productive well into the future. The VTI Belgrade T-38 wind tunnel responded to these challenges by applying a hierarchical approach to design a distributed multilevel control system, a part of which is the variable-geometry nozzle positioning system, presented in this paper. It follows the hierarchy of the entire wind tunnel control system, with critical positioning loops at the field-programmable gate array (FPGA), and the user interface with real-time data analysis capability implemented on a central wind tunnel computer. In addition to more accurate positioning, the FPGA-based control system significantly improved overall operation efficiency, speed and reliability. Since the nozzle geometry uniquely determines supersonic Mach number, the improved positioning accuracy is verified in wind tunnel tests","PeriodicalId":33842,"journal":{"name":"Scientific Technical Review","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71083873","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}
Hicham Kemmoukhe, Sasa Savic, Slavica Terzić, M. Lisov, N. Rezgui, Housseyn Sedra
In order to enhance the penetration capability of the shaped charge jet, different liner forms are used. These modifications help to increase the jet tip velocity, as well as to improve the distribution of the kinetic energy. AUTODYN software is used to perform these numerical simulations. Euler solver of the AUTODYN is used to simulate the jet formation and Lagrange solver is used for penetration problem. Numerical results have good agreement with the available experimental results from the literature. For the same charge calibre and main charge length, several liner forms as conical, circle and trumpet are investigated. Results show that the trumpet form has a higher penetration capability than other forms. Distribution of kinetic energy along the liner with variable liner thickness is more suitable to get higher cumulative jet efficiency on the target
{"title":"Improvement of the shaped charge jet penetration capability by modifying the liner form using AUTODYN-2D","authors":"Hicham Kemmoukhe, Sasa Savic, Slavica Terzić, M. Lisov, N. Rezgui, Housseyn Sedra","doi":"10.5937/STR1901010K","DOIUrl":"https://doi.org/10.5937/STR1901010K","url":null,"abstract":"In order to enhance the penetration capability of the shaped charge jet, different liner forms are used. These modifications help to increase the jet tip velocity, as well as to improve the distribution of the kinetic energy. AUTODYN software is used to perform these numerical simulations. Euler solver of the AUTODYN is used to simulate the jet formation and Lagrange solver is used for penetration problem. Numerical results have good agreement with the available experimental results from the literature. For the same charge calibre and main charge length, several liner forms as conical, circle and trumpet are investigated. Results show that the trumpet form has a higher penetration capability than other forms. Distribution of kinetic energy along the liner with variable liner thickness is more suitable to get higher cumulative jet efficiency on the target","PeriodicalId":33842,"journal":{"name":"Scientific Technical Review","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71084513","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}
Miodrag Milenković-Babić, V. Antonić, Mišo Prodić, Vanja Stefanović-Gobeljić, R. Radonjić, Stevan S. Jovičić, N. Nedic
Analysis of the take-off and landing distance of a single tractor propelled aircraft LASTA is presented in this paper. The purpose of the analysis is to enable certification of the LASTA aircraft according to civil regulations CS-23. The paper presents the approximated method for calculating take-off and landing distance and compares it with the flight test results. Good agreement between these two results is obtained
{"title":"Aircraft LASTA take-off and landing performance","authors":"Miodrag Milenković-Babić, V. Antonić, Mišo Prodić, Vanja Stefanović-Gobeljić, R. Radonjić, Stevan S. Jovičić, N. Nedic","doi":"10.5937/STR1901032M","DOIUrl":"https://doi.org/10.5937/STR1901032M","url":null,"abstract":"Analysis of the take-off and landing distance of a single tractor propelled aircraft LASTA is presented in this paper. The purpose of the analysis is to enable certification of the LASTA aircraft according to civil regulations CS-23. The paper presents the approximated method for calculating take-off and landing distance and compares it with the flight test results. Good agreement between these two results is obtained","PeriodicalId":33842,"journal":{"name":"Scientific Technical Review","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71084382","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}
J. Bogdanov, Uroš Anđelić, Z. Bajić, S. Brzić, Jovica Nešić
The experimental research on shape of detonation wave was done for cylindrical explosive charges with 5 different energetic materials with nitrocellulose and nitroglycerine. Energetic materials were manufactured with the technology for production of ball propellants. Shape of detonation wave was determined using the method of measurement of detonation wave arrival time to a certain point in the charge. Measurement system was developed in the Military Technical Institute (VTI) in Belgrade and had 16 fibre optic cables, multi-channel optical signal detector and oscilloscope. Curvature of detonation wave was determined at two different distances from initiation point. Average radii of detonation waves were determined using the regression analysis of experimental data. Also, the change in detonation wave curvature was observed at different distances from the detonator.
{"title":"Shape of detonation wave in different energetic materials based on nitrocellulose and nitroglycerine","authors":"J. Bogdanov, Uroš Anđelić, Z. Bajić, S. Brzić, Jovica Nešić","doi":"10.5937/str1902032b","DOIUrl":"https://doi.org/10.5937/str1902032b","url":null,"abstract":"The experimental research on shape of detonation wave was done for cylindrical explosive charges with 5 different energetic materials with nitrocellulose and nitroglycerine. Energetic materials were manufactured with the technology for production of ball propellants. Shape of detonation wave was determined using the method of measurement of detonation wave arrival time to a certain point in the charge. Measurement system was developed in the Military Technical Institute (VTI) in Belgrade and had 16 fibre optic cables, multi-channel optical signal detector and oscilloscope. Curvature of detonation wave was determined at two different distances from initiation point. Average radii of detonation waves were determined using the regression analysis of experimental data. Also, the change in detonation wave curvature was observed at different distances from the detonator.","PeriodicalId":33842,"journal":{"name":"Scientific Technical Review","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71084839","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}
Ljiljana Jelisavac, S. Stojiljković, S. Brzić, Jovica Nešić, Bojana Z. Fidanovski, Bojan Tanaskovski
{"title":"Modification of AOP-48 Ed. 2 extrapolation expression by introduction of real storage t-T conditions of naturally aged nitrocellulose gun powder","authors":"Ljiljana Jelisavac, S. Stojiljković, S. Brzić, Jovica Nešić, Bojana Z. Fidanovski, Bojan Tanaskovski","doi":"10.5937/str1903049j","DOIUrl":"https://doi.org/10.5937/str1903049j","url":null,"abstract":"","PeriodicalId":33842,"journal":{"name":"Scientific Technical Review","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"71084889","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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