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High-Velocity Projectile Impact Behaviour of Friction stir Welded AA7075 Thick Plates

Defence Technology（防务技术） 2023年第11期29卷 153-163页

作者： r.Praveen s.r.koteswara rao G.selvakumar r.Damodaram Department of robotics and Automation Karpaga Vinayaga College of Engineering and TechnologyChengalpattu603308TamilNaduIndia Department of Mechanical Engineering Sri Sivasubramaniya Nadar College of EngineeringChennai603110TamilNaduIndia

In this study, high velocity impact behaviour of friction stir welded AA7075-T651 25 mm thick plates were investigated using a 7.62 mm × 51 mm lead core and 7.62 mm × 39 mm steel core projectiles. Prior to ballistic trails, mechanical and metallurgical properties of friction stir welded AA 7075-T651 25 mm thick plates were studied. Microstructural and hardness studies revealed that friction stir welds constituted three distinct regions namely Weld Nugget(WN), Thermo-Mechanically Affected Zone(TMAZ) and Heat Affected Zone(HAZ). Base Material(BM) and all three weld regions were ballistically tested as per military standard NIJ.0108.01 using lead and steel core bullets at maximum permissible velocities of 830 ± 20 and 700 ± 30 m/s, respectively. It has been found that base material(AA7075-T651)and all three weld regions of 25 mm thick plates were able to resist perforation by both types of projectiles used. However depth of penetration has been found to increase from BM to WN, HAZ and TMAZ for both types of projectiles. In all cases steel core projectiles caused higher depth of penetration compared to those caused by lead core projectiles. TMAZs of the friction stir welds were found to be the weakest zone. The fracture that occurred in the base material was spall fragmentation indicating brittle failure, whereas all zones of friction stir welded AA7075-T651 targets with a front petalling, indicating ductile failure. The post-ballistic tested samples showed no significant change in the microstructure of the BM and WN. On the other hand, TMAZ and HAZ showed severe grain deformation in the direction of projectile penetration, and the formation of adiabatic shear bands(AsB). This work showed that 25 mm thick friction stir welded AA7075-T651 joints responded well to ballistic impact loads, making them a good choice for light combat vehicles.

关键词： Aluminum alloy Thick plate Friction stir welding Ballistic performance Depth of penetration

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Microstructure and mechanical properties of friction stir welded AA7075-T651 aluminum alloy thick plates

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Transactions of Nonferrous Metals society of China 2015年第6期25卷 1770-1778页

作者： T.srINIVAsA rao G.MADHUsUDHAN rEDDY s.r.koteswara rao Department of Mechanical Engineering Tagore Engineering College Metal Joining Group Defense Metallurgical Research Laboratory Department of Mechanical Engineering SSN College of Engineering

Friction stir butt welding of AA7075-T651 plates with thicknesses of 10 and 16 mm was investigated. Defect-free, full- penetration welds were obtained after careful process parameter selection. While the nuggets in both welds exhibited very fine reerystallized grains, and finer grains were observed in welds made on 10 mm thick plates. Microhardness surveys revealed that significant loss in hardness occurs in the heat-affected zone. The reduction in hardness due to the welding process is higher in the case of welds made on 16 mm thick plates. Welds made on 10 mm thick plates exhibited superior tensile properties compared with those made on 16 mm thick plates. Fracture during tensile test occurred in the heat-affected zone in both cases. TEM images of specimens revealed that the heat-affected zone consisted of widened precipitate-free zones along grain boundaries and partial dissolution of precipitates in the grain interiors. It is concluded that defect-free single pass welds can be made on AA7075-T651 thick plates using friction stir welding and the welds made on 10 mm thick plates exhibit high joint efficiency.

关键词： AA7075-T651 aluminum alloy friction stir welding microstructure mechanical properties

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Infrared small target detection based on spatial attention density peaks searching

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Optoelectronics Letters 2025年第2期21卷 90-96页

作者： rao Junmin LU siyu LIU shijian LI Fanming CAs Key Laboratory of Infrared system Detection and Imaging Technology Shanghai Institute of Technical Physics University of Chinese Academy of sciences shanghai Institute of Technical Physics Chinese Academy of Sciences school of Information science and Technology Shanghai Tech University

The detection of small targets poses a significant challenge for infrared search and tracking (IrsT) systems,as they must strike a delicate balance between accuracy and *** this paper,we propose a detection algorithm based on spatial attention density peaks searching (sADPs) and an adaptive window selection ***,the difference-of-Gaussians (DoG) filter is introduced for preprocessing raw infrared ***,the image is processed by ***,an adaptive window selection scheme is applied to obtain window templates for the target scale ***,the small target feature is used to enhance the target and suppress the ***,the true targets are segmented through a *** experimental results show that compared with the seven state-of-the-art small targets detection baseline algorithms,the proposed method not only has better detection accuracy,but also has reasonable time consumption.

关键词： Infrared imaging

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Measure of nonlinearity for underwater target tracking using hull-mounted sensor

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International Journal of Intelligent Computing and Cybernetics 2022年第3期15卷 333-344页

作者： B.Omkar Lakshmi Jagan s.koteswara rao Department of Electrical and Electronics Engineering Koneru Lakshmaiah Education FoundationGunturIndia Department of Electronics and Communication Engineering Koneru Lakshmaiah Education FoundationGunturIndia

Purpose-Doppler-Bearing Tracking(DBT)is commonly used in target tracking applications for the underwater environment using the Hull-Mounted sensor(HMs).It is an important and challenging problem in an underwater ***/methodology/approach-The system nonlinearity in an underwater environment increases due to several reasons such as the type of measurements taken,the speeds of target and observer,environmental conditions,number of sensors considered for measurements and so *** of nonlinearity(DoNL)for these problems are analyzed using a proposed measure of nonlinearity(MoNL)for state ***-In this research,the authors analyzed MoNL for state estimation and computed the conditional MoNL(normalized)using different filtering algorithms where measurements are obtained from a single sensor array(***).MoNL is implemented to find out the system nonlinearity for different filtering algorithms and identified how much nonlinear the system is,that is,to measure nonlinearity of a ***/value-Algorithms are evaluated for various scenarios with different angles on the target bow(ATB)in Monte-Carlo *** of root mean squared(rMs)errors in position and velocity is carried out to assess the state estimation accuracy using MATLAB.

关键词： Nonlinear filtering statistical signal processing Underwater target tracking Estimation theory Hull-mounted sensor

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Pervasive underwater passive target tracking for the computation of standard deviation solution in a 3D environment

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International Journal of Intelligent Computing and Cybernetics 2021年第4期14卷 580-597页

作者： M.Kavitha Lakshmi s.koteswara rao Kodukula subrahmanyam Computer science and Engineering Koneru Lakshmaiah Education FoundationGunturIndia Electronics and Communications Engineering Koneru Lakshmaiah Education FoundationGunturIndiaand

Purpose-Nowadays advancement in acoustic technology can be explored with marine *** purpose of the paper is pervasive computing underwater target tracking has aroused military and civilian interest as a key component of ocean *** many pervasive techniques are currently found in the literature,there is little published research on the effectiveness of these paradigms in the target tracking ***/methodology/approach-The unscented Kalman filter(UKF)provides good results for bearing and elevation angles only *** methodology and mathematical modeling are carried out and used to analyze the performance of the filter based on the Monte Carlo ***-Due to the intricacy of maritime surroundings,tracking underwater targets using acoustic signals,without knowing the range parameter is *** intention is to find out the solution in terms of standard deviation in a three-dimensional(3D)***/value-A new method is found for the acceptance criteria for range,course,speed and pitch based on the standard deviation for bearing and elevation 3D target tracking using the unscented Kalman filter covariance *** the Monte Carlo simulation,several scenarios are used and the results are shown.

关键词： Unscented Kalman filter Underwater target tracking Acceptance criteria Three-dimensional target tracking standard deviation

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stiffness of a 3-degree of freedom translational parallel kinematic machine

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Frontiers of Mechanical Engineering 2014年第3期9卷 233-241页

作者： s. sHANKAr GANEsH A.B. koteswara rao Department of Mechanical Engineering Gayatri Vidya Parishad College of Engineering Visakhapatnam 530048 India

In this paper, a typical 3-degree of freedom （3- DOF） translational parallel kinematic machine （PKM） is studied and analyzed whose tool platform has only translations along X-, Y- and Z-axes. It consists of three limbs, each of which have arm and forearm with prismatic- revolute-revolute-revolute （Prrr）joints. Inverse kine- matics analysis is carried out to find the slider coordinates and joint angles for a given position of tool platform. stiffness modeling is done based on the compliance matrices of arm and forearm of each limb. Using the stiffness modeling the variations of minimum and max- imum translational stiffness in the workspaee are analyzed. For various architectural parameters of the 3-DOF PKM the tendency of variations on the minimum and maximum stiffness over the entire workspace is studied; and also the deflections of the tool platform along X, Y, and Z directions with respect to various forces are presented.

关键词： 3-DOF translational PKM inverse kine-matics stiffness modeling translational stiffness

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Prevalence of shifted rayleigh filter for passive surveillance in underwater

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International Journal of Intelligent Computing and Cybernetics 2022年第1期15卷 110-123页

作者： Guduru Naga Divya sanagapallea koteswara rao Department of Electronics and Communication Engineering Koneru Lakshmaiah Education FoundationGunturIndia

Purpose-From many decades,bearings-only tracking(BOT)is the interested problem for *** utilises nonlinear filtering methods for state estimation as there is only information about the target,*** is a nonlinear *** measurement bearing is tangentially related to the target state *** are many nonlinear filtering algorithms developed so far in the ***/methodology/approach-In this research work,the recently developed nonlinear filtering algorithm,*** rayleigh filter(srF),is applied to ***-The srF is tested for two-dimensional BOT against various *** simulation results emphasise that the srF performs well when compared to the standard nonlinear filtering algorithm,unscented Kalman filter(UKF).Originality/value-srF utilises the nonlinearities present in the bearing measurement through the use of moment *** srF is able to produce the solution in highly noisy environment,long ranges and high dimension tracking.

关键词： stochastic signal processing shifted rayleigh filter state estimation Underwater surveillance

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Design of Multi-Valued Logic Circuit Using Carbon Nano Tube Field Transistors

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Computers, Materials & Continua 2022年第12期73卷 5283-5298页

作者： s.V.ratankumar L.koteswara rao M.Kiran Kumar Department of Electronics and Communication Engineering Koneru Lakshmaiah Education FoundationAziz NagarHyderabad500075TelanganaIndia Department of Electronics and Communication Engineering RGM College of Engineering and TechnologyNandyal518501Andhra PradeshIndia Department of Electrical and Electronics Engineering Koneru Lakshmaiah Education FoundationVaddeswaramGuntur522502Andhra PradeshIndia

The design of a three-input logic circuit using carbon nanotube field effect transistors(CNTFETs)is *** logic must be an exact replacement for dual logic since it performs straightforwardly in digital devices,which is why this design is so popular,and it also reduces chip area,both of which are examples of circuit *** proposed module we have investigated is a triple-logic-based one,based on advanced technology CNTFETs and an emphasis on minimizing delay times at various values,as well as comparisons of the design working with various load *** the proposed design with the existing design,the delay times was reduced from 66.32 to 16.41 ps,i.e.,a 75.26%***,the power dissipation was not optimized,and increased by 1.44%compared to the existing *** number of transistors was also reduced,and the product of power and delay(P∗D)achieved a value of 0.0498053 *** improvement at 1 V was also achieved.A load capacitance(fF)was measured at different values,and the average delay measured for different values of capacitance had a maximum of 83.60 ps and a minimum of 22.54 ps,with a range of 61.06 *** power dissipations ranged from a minimum of 3.38μW to a maximum of 6.49μ*** on these results,the use of this CNTFET half-adder design in multiple Boolean circuits will be a useful addition to circuit design.

关键词： Carbon nanotube field effect transistor(CNTFET) multivalued logic(MVL) ternary adder Hewlett simulation program with integrated circuit emphasis(HsPICE) chirality(nm) adder

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Passive activity enhances residual control ability in patients with complete spinal cord injury

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Neural regeneration research 2025年第8期20卷 2337-2347页

作者： Yanqing Xiao Mingming Gao Zejia He Jia Zheng Hongming Bai Jia-sheng rao Guiyun song Wei song Xiaoguang Li Beijing Key Laboratory for Biomaterials and Neural regeneration Beijing Advanced Innovation Center for Biomedical EngineeringSchool of Biological Science and Medical EngineeringBeihang UniversityBeijingChina Department of rehabilitation Evaluation China Rehabilitation Research CenterBeijingChina Cardiac Center Beijing Children’s HospitalCapital Medical UniversityBeijingChina The state Key Laboratory of Virtual reality Technology and systems Beihang UniversityBeijingChina Department of rehabilitation Engineering China Rehabilitation Science InstituteBeijingChina

Patients with complete spinal cord injury retain the potential for volitional muscle activity in muscles located below the spinal injury ***,because of prolonged inactivity,initial attempts to activate these muscles may not effectively engage any of the remaining neurons in the descending pathway.A previous study unexpectedly found that a brief clinical round of passive activity significantly increased volitional muscle activation,as measured by surface *** this study,we further explored the effect of passive activity on surface electromyographic signals during volitional control tasks among individuals with complete spinal cord *** patients with chronic complete thoracic spinal cord injury were *** electromyography data from eight major leg muscles were acquired and compared before and after the passive activity *** results indicated that the passive activity led to an increased number of activated volitional muscles and an increased frequency of *** the cumulative root mean square of surface electromyography amplitude for volitional control of movement showed a slight increase after passive activity,the difference was not statistically *** findings suggest that brief passive activity may enhance the ability to initiate volitional muscle activity during surface electromyography tasks and underscore the potential of passive activity for improving residual motor control among patients with motor complete spinal cord injury.

关键词： complete spinal cord injury cycle training epidural electrical stimulation motor training passive activity physiological state spinal cord circuit surface electromyography volitional control task

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Error analysis and optimization of a 3-degree of freedom translational Parallel Kinematic Machine

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Frontiers of Mechanical Engineering 2014年第2期9卷 120-129页

作者： s. sHANKAr GANEsH A. B. koteswara rao Department of Mechanical Engineering G.V.E College of Engineering Visakhapatnam 530048 India

In this paper, error modeling and analysis of a typical 3-degree of freedom translational Parallel Kine- matic Machine is presented. This mechanism provides translational motion along the Cartesian X-, Y- and Z- axes. It consists of three limbs each having an arm and forearm with prismatic-revolute-revolute-revolute joints. The moving or tool platform maintains same orientation in the entire workspace due to its joint arrangement. From inverse kinematics, the joint angles for a given position of tool platform necessary for the error modeling and analysis are obtained. Error modeling is done based on the differentiation of the inverse kinematic equations. Variation of pose errors along X, Y and Z directions for a set of dimensions of the parallel kinematic machine is presented. A non-dimensional performance index, namely, global error transformation index is used to study the influence of dimensions and its corresponding global maximum pose error is reported. An attempt is made to find the optimal dimensions of the Parallel Kinematic Machine using Genetic Algorithms in MATLAB. The methodology presented and the results obtained are useful for predicting the performance capability of the Parallel Kinematic Machine under study.

关键词： translational Parallel Kinematic Machine error modeling global error transformation index

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