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Numerical and Experimental Investigation of a Short Recoil Operated Weapon and Impact of Construction Characteristics on its Operation Cycle
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Estimation of kinematic and dynamic parameters of weapon mechanisms during operation is one of the crucial elements of design and optimisation. This study presents results of numerical and experimental investigations of a short-recoil-operated weapon action cycle. Theoretical considerations were based on multibody systems and finite element approaches. An experimental stand was adopted to investigate the kinematic characteristics of pistol parts and provide a set of slide displacement and velocity time courses. Comparison of theoretical and experimental data allowed for positive validation of the investigated model. The multibody systems numerical approach ensured a maximum relative discrepancy with experiment of 3.5 per cent for the velocity of recoiled parts, while finite element analysis calculations yielded a value of 12.7 per cent. Finally, parametric analyses were conducted to determine the influence of selected design characteristics on weapon operation. The analyses proved the correctness of the adopted design assumptions
Manoeuvring simulations of Autonomous Underwater Vehicle using quaternion
Get PDFThe dynamics of an autonomous underwater vehicle (AUV), which can perform manoeuvres with pitch angles in the range of 90° is investigated in this paper. The purpose of the AUV is to perform station keeping manoeuvre at about 90° pitch angle by varying propeller revolution. The AUV is launched / retrieved in horizontal orientation. Quaternion mathematics, 4 quadrant propeller open water characteristics and PID controller for propeller revolution are incorporated in manoeuvring mathematical model for this purpose. A procedure for optimizing the gain coefficients for the PID controller is developed using the manoeuvring mathematical model. Two design configuration of the AUV are investigated, positively buoyant and negatively buoyant. It is shown that both the optimal gain coefficients for the PID controller for propeller revolution and dynamic response of the AUV are different for each design configuration. 
Simple and Efficient Group Key Distribution Protocol using Matrices
Get PDFGroup Key Distribution (GKD) protocols are designed to distribute a group key to several users for establishing a secure communication over a public network. The central trusted authority, called the key distribution center (KDC) is in charge of distributing the group keys. For securing the communication, all the users share a common secret key in advance with KDC. In this paper, we propose a secure and efficient Group Authenticated Key Distribution (GAKD) protocol based on the simple idea of encryption in matrix rings. In this protocol, each user registers in private with the KDC, while all the other information can be transferred publicly. The scheme also supports authentication of group keys without assuming computational hard problems such as Integer Factorization Problem (IFP).The analysis of our GAKD protocol shows that the proposed protocol is resistant to reply, passive and impersonation attacks. Our construction leads to a secure, cost and computation- effective GAKD protocol
An Optimal Retinanet Model For Automatic Satellite Image Based Missile Site Detection
Get PDFSatellite image processing is a manually tedious job and offers scope for automation as part of the information extraction process from satellite images. The process of information extraction involves object detection and one of the challenges is ascertaining the minimum number of images required to train the deep learning model to achieve a certain minimum accuracy. To the best of the authors’ knowledge, work in missile site detection is relatively limited, with an existing exploration of the latest one-shot detection methods, such as RetinaNet, being absent. This work proposes an optimal deep learning model based on the RetinaNet framework and training on a minimal dataset. A comparative analysis with previous work paves the road for future research in one-shot methods and optimally trained models. As part of the study, the key findings are that an optimal training scheme based on a minimal training dataset is possible. This step enables a reduction in training time for the development of an optimal missile site detection model is concerned. One of the many techniques to determine the minimal number of training images required to train the object detection model is plotting the number of training images versus the mean average precision. The same is validated in our work. Further, a hybrid scheme based on the two-model concept is tested wherein one model prioritizes Recall while the other prioritizes Precision. Thus a combination of both models to detect a set of targets provides an optimal framework for object detection. Lastly, the study finds that the single-stage RetinaNet algorithm offers the advantage of balancing speed and accuracy over erstwhile two-stage and other single-stage methods
Plastic Deformation of High Explosive Projectile 155 mm during Gun Launch Conditions using Finite Element Method
Get PDFThe structural integrity of artillery projectile 155mm high explosive Extended Range Full Bore (ERFB)boat tail designed for 155mm howitzer guns of 39, 45 and 52 calibre plays a key role inside the gun barrel. Thisprojectile comprises a shell body, a driving band, a boat tail, nubs, an explosive, and a fuze. Plastic deformationof the projectile and stripping of driving band are not permitted, when projectile is fired. An investigational study is necessitated to check the plastic deformation of the projectile subjected to maximum propellant charge pressure.The aim of this study is to check the effective plastic deformation and affirm the structural integrity. A 3-D explicit dynamic structural analysis of 155 mm HE ERFB BT during gun launch conditions is carried out by finite element method using FE code ABAQUS/Explicit. To understand the non-linear mechanical behavior of the projectile, the true stress-strain curves of the materials are considered. The plastic behavior of the projectile subjected to the time-dependent loading is studied by using the von Mises plasticity model. The results reveal that the shell body and boat tail have no plastic deformation and the most stressed component is the driving band. The investigation has affirmed the structural integrity of the projectile during gun launch conditions
Maximizing the Number of Spatial Nulls with Minimum Sensors
Get PDFIn this paper, we attempt to unify two array processing frameworks viz, Acoustic Vector Sensor (AVS) and two level nested array to enhance the Degrees of Freedom (DoF) significantly beyond the limit that is attained by a Uniform Linear Hydrophone Array (ULA) with specified number of sensors. The major focus is to design a line array architecture which provides high resolution unambiguous bearing estimation with increased number of spatial nulls to mitigate the multiple interferences in a deep ocean scenario. AVS can provide more information about the propagating acoustic field intensity vector by simultaneously measuring the acoustic pressure along with tri-axial particle velocity components. In this work, we have developed Nested AVS array (NAVS) ocean data model to demonstrate the performance enhancement. Conventional and MVDR spatial filters are used as the response function to evaluate the performance of the proposed architecture. Simulation results show significant improvement in performance viz, increase of DoF, and localization of more number of acoustic sources and high resolution bearing estimation with reduced side lobe level
Research on A Novel Reliable MEMS Bistable Solid State Switch
Get PDFAs a result of the unpredictable nature of extreme environments (including temperature, humidity, impact, and other factors), micro-electro-mechanical systems (MEMS) solid-state fuze control modules have an urgent requirement for a MEMS solid-state switch (MEMS-S3). In particular, this switch must remain stable without any energy input after a state transition (i.e., it must be bistable). In this paper, a MEMS bistable solid-state switch (MEMS-bS3) is designed that is based on the concept of producing a micro-explosion. The reliable state switching of the MEMS-bS3 is studied via heat conduction theory and verified via both simulations and experimental methods. The experimental results show that these switches can produce micro-explosions driven by 33 V/47 μF pulse energy. However, the metal film bridge (MFB) structures used in this switch with smaller dimensions (80×20 μm2, 90×30 μm2, and 100×40 μm2) could not enable the switch to realize a reliable state transition, and the state transition rate was less than 40%. When the MFB dimensions reached 120×60 μm2 or 130×70 μm2, the state transition rate exceeded 80%, and the response time was on the μs-scale
Optimal Design of Hydraulic Disc Brake for Magnetorheological (MR) Application
Get PDFThis paper aims to provide a new design considering compressive force application in the MR fluid andimprove its braking torque by optimizing it. According to the current study, compressing the MR region will increase braking torque compared to no compression. The area covered by an existing model of the conventional disc brake is taken into consideration for the unique design of the MR brake to operate in shear and compression mode, and the required compression given by the hydraulic pressure similar to a conventional disc brake. The suggested MR brake’s structural layout is presented. The Herschel-Bulkley shear thinning model’s mathematical expression for the torque equation for the compression and shear modes is provided. An analytical magnetic circuit is done for the proposed design for determining the relationship between applied current and magnetic field strength as a function of the geometrical and material attributes of the MR brake. Simulation is done on COMSOL software with the help of an AC/DC module, considering the non-linear relationship between the magnetic field and magnetic flux. Simulation results of braking torque achieved with the varying current are determined. The graph displays the braking torque for current in the compression plus shear mode as well as shear mode. After that, optimization is done on the proposed model for optimal design parameters. For optimization, we adopt the most popular Genetic Algorithm (GA) method. Optimization aims to increase the braking torque capacity of the MR brake for the given volume
Thermal Study of 155 mm Gun Barrel
Get PDFThermal analysis of 155 Gun barrel is an important aspect of designing the gun barrel and deciding the maximum firing rate. The performance of any artillery depends upon the thermal behaviour of the gun barrel among various factors, and its availability for continuous firing depends on the maximum bore temperature and cook-off time of the barrel. In this paper, the effect of maximum bore temperature, cook-off, active cooling is reviewed. Heat transfer to the gun barrel surface is calculated using analytical analysis with given ammunition parameters. Analytical and finite element analysis of maximum bore temperature and cook-off time is also included. Finite element analysis of external Jacket water cooling of the barrel shows that the gun can fire continuously at three rounds per minute without reaching cook-off temperature