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Hardware in the Loop Simulation and Control Design for Autonomous Free Running Ship Models
Get PDFThis paper presents an hardware-in-the-loop (HIL) simulation system tool to test and validate an autonomous free running model system for ship hydrodynamic studies with a view to verification of the code, the control logic and system peripherals. The computer simulation of the plant model in real-time computer does not require the actual physical system and reduces the development cost and time for control design and testing purposes. The HIL system includes: the actual programmable embedded controller along with peripherals and a plant model virtually simulated in a real-time computer. With regard to ship controller design for ship model testing, this study describes a plant model for surge and a Nomoto first order steering dynamics, both implemented using Simulink software suit. The surge model captures a quasi-steady state relationship between surge speed and the propeller rpms, obtained from simple forward speed towing tank tests or derived analytically. The Nomoto first order steering dynamics is obtained by performing the standard turning circle test at model scale. The control logic obtained is embedded in a NI-cRIO based controller. The surge and steering dynamics models are used to design a proportional-derivative controller and an LQR controller. The controller runs a Linux based real-time operating system programmed using LabVIEW software. The HIL simulation tool allows for the emulation of standard ship hydrodynamic tests consisting of straight line, turning circle and zigzag to validate the combined system performance, prior to actual for use in the autonomous free-running tests
Design of RF Receiver Front end Subsystems with Low Noise Amplifier and Active Mixer for Intelligent Transportation Systems Application
Get PDFThis paper presents the design, simulation, and characterization of a novel low-noise amplifier (LNA) and active mixer for intelligent transportation system applications. A low noise amplifier is the key component of RF receiver systems. Design, simulation, and characterization of LNA have been performed to obtain the optimum value of noise figure, gain and reflection coefficient. Proposed LNA achieves measured voltage gains of ~18 dB, reflection coefficients of -20 dB, and noise figures of ~2 dB at 5.9 GHz, respectively. The active mixer is a better choice for a modern receiver system over a passive mixer. Key sight advanced design system in conjunction with the electromagnetic simulation tool, has been to obtain the optimal conversion gain and noise figure of the active mixer. The lower and upper resonant frequencies of mixer have been obtained at 2.45 GHz and 5.25 GHz, respectively. The measured conversion gains at lower and upper frequencies are 12 dB and 10.2 dB, respectively. The measured noise figures at lower and upper frequencies are 5.8 dB and 6.5 dB, respectively. The measured mixer interception point at lower and upper frequencies are 3.9 dBm and 4.2 dBm
Analysis of Operating Principles and Flow Field Characteristics for a Diving Ballast Tank
Get PDFOperating principle and flow field characteristics of a diving ballast tank for application in submerged vehicles were investigated in the present study. As understanding the complex changes in the interior air-water two-phase flow field of the ballast tank during the diving process is difficult, this study specifically performed a ballast tank diving experiment. Experimental and numerical simulations to analyse the diving motions of the ballast tank were conducted. Authors comprehensively evaluated the flow field changes in the ballast tank and its surroundings. The experimental and numerical results were compared in terms of the observed displacements and velocities during diving. Both the results indicated similar motion trajectories and velocities. Authors effectively observed the air-water two-phase flow field change inside the ballast tank using this numerical method. Therefore, the numerical model constructed in this study can be useful for analysing the diving motions of ballast tanks and can effectively predict the interior flow field characteristics of a ballast tank
Potential of Multi constellation Global Navigation Satellite System in Indian Missile Test Range Applications
Get PDFIn this paper, the potentials of using Global Navigation Satellite System (GNSS) techniques in the complex calibration procedure of the tracking sensors for missile test range applications have been presented. The frequently used tracking sensors in test range applications are- electro-optical tracking stations (EOTS) and tracking radars. Over the years, the EOTS are used as the reference for bias estimation of the radars. With the introduction of GPS in test range applications, especially the DGPS, the reference for bias estimation got shifted to DGPS from the EOTS. However, the achievable position solution accuracy is limited to the order of a few meters for DGPS, EOTS, and Radars. With the evolution of Multi-constellation GNSS and carrier-phase based measurement techniques in satellite navigation, achievable position solution accuracies may be improved to sub-meter level. New navigation techniques like real time kinematic (RTK) and precise point positioning have the potentials for use in the calibration procedures of the missile test ranges to the accuracies of centimeter-level. Moreover, because of the availability of a large number of navigation signals over the Indian region, multi-constellation GNSS receivers can enhance signal availability, reliability, and accuracies during the calibration of missile test ranges. Currently available compact, low-cost GNSS modules also offer the possibilities of using these for cost-effective, networked RTK for dynamic calibration of test ranges reducing cost and resource requirements
Deciphering the Puzzle of Hypobaric Hypoxia Proteomics Prophylaxis and Modelling Approach
Get PDFHypoxia, particularly hypobaric hypoxia, is a multifaceted entity which includes certain molecular, patho-physiological and biochemical aspects. Any single aspect in itself cannot help us elucidate hypobaric hypoxia in its entirety. We observed three crucial lacunae within the existing literature. These include a lack of high-throughput investigations into redox PTMs, particularly NO-based PTMs; a prophylactic supplement with proven efficacy and safety which doesn’t involve medical supervision and is not contraindicated in hepatic, renal and cardiac insufficiencies; and a clinically validated rodent model of HAPE without any genetic/pharmacological manipulations. In the present study, we present an antagonistic interplay between nitrosylation and carbonylation which shows an additional NO-based network that is active in acclimatised individuals. Then we present a micronised aqueous suspension of silymarin which is efficacious at low doses in providing antioxidant, anti-inflammatory and hypoxia-adaptive vascular responses in addition to being a free radical quencher itself. Silymarin has an excellent safety and efficacy profile in humans. Finally, we create a SD rat model of HAPE which was used to reverse-translate a previously known HAPE marker in humans (SULT1A1) and elucidate the synergistic occurrence of HAPE and inflammation cascades. This is the first radiologically validated rodent HAPE model. In conclusion, we were able to elucidate the molecular, biochemical and patho-physiological aspects of hypobaric hypoxia which were left out by previous studies
Determination of Delay in Detonation of a Sandwiched Explosive Impacted by a Shaped Charge Jet
Get PDFA simple analytical model has been developed to determine delay in detonation of an explosive sandwiched between two metal plates and impacted by a shaped charge jet. The analytical model consists of a relation between detonation delay and depth of jet penetration in a target kept in contact across the explosive sandwich. This relation is derived by expressing depth of jet penetration P as a function of detonation delay Tdx and duration Tw of free passage of the jet through the hole in the top plate of the sandwich. One more relation between Tdx and Tw has been obtained from the theory of expansion of hole produced in a metal plate by jet impact. These two relations have been solved simultaneously to get values of both these parameters as a function of jet penetration. It is proposed that this analytical model can be used in two ways. First, this model can be used to calculate detonation delay by experimental measurement of jet penetration in a target. The detonation delay thus determined can be used to calculate insensitivity constant Aj of an explosive. Second, this model can be used to theoretically calculate jet penetrations obtained by different shaped charge warheads when using a sandwich of explosive with a given insensitivity. Both uses of this analytical model are illustrated using numerical examples
A Multi segment Morphing System for a Micro Air Vehicle using Shape Memory Alloy Actuators
Get PDFA configurable multi-segment morphing system for a micro air vehicle (MAV) is presented in this study. One of the novelties is the development of an adaptive control allocation algorithm that provides fast, simultaneous and independent operation of four morphing segments using shape memory alloy (SMA) actuators. The SMA operation is time-staggered in microsecond resolution to ensure that only one SMA draws power from the MAV battery at a time. The other novelties are the in-flight measurement of morphing angle using dual flex-sensors and morphing of leading edges such that the ‘morphing-line’ is diagonal (45º) to the MAV’s lateral axis. The system was implemented on an open source autopilot controller and operated using the MAV battery. It was ground-tested under propeller ON conditions and a droop rate of 35º/s and ability to track a 1 Hz sinusoidal variation of droop angle were realised
Low Temperature Vulcanisation Technique for CR BIIR Blend for Encapsulation of Oceanic Sensors
Get PDFBlend of chloroprene rubber (CR) and bromobutyl rubber (BIIR) is used for encapsulation of piezo sensors used in sea water. Conventional encapsulation method of these sensors involving high temperature vulcanisation (HTV) often leads to deterioration of piezo properties due to thermal degradation. This paper reports a low temperature vulcanisation (LTV) technique carried out at 90 °C for CR-BIIR blend using chlorinated polyethylene (CPE) as compatibiliser and LTV system consisting of modified di-o-tolyl guanidine and thiocarbanilide as accelerators and ZnO as curing agent. The conventionally used scavenger MgO was eliminated and only ZnO was used to boost the cure reaction. Properties specific to sonar sensors, namely, acoustic transparency, electrical resistivity, water absorption and physico‑mechanical properties were evaluated besides evaluation of morphology. The results are found to compare better than the conventional blend. Accelerated thermal ageing at 70 °C for 7 days yielded 97 % retention of tensile strength. The technique was implemented in a PZT hydrophone sensor and was successfully underwater tested
Comparative Analysis of Static Loading Performance of Rigid and Flexible Road Wheel based on Finite Element Method
Get PDFTo overcome the shortcomings of traditional rigid road wheel, such as poor damping effect and low load-bearing efficiency, a new type of flexible road wheel, having a unique suspension-bearing mode, was introduced. The three-dimensional nonlinear finite element model of rigid and flexible road wheel, considering the triple nonlinear characteristics of geometry, material and contact, is established for numerical investigation of static loading performance. The accuracy of the finite element model of the rigid and flexible road wheel is verified by static loading experiment. The static loading performance of the rigid and flexible road wheels is numerically analyzed. The influence of vertical load on maximum stress and deformation of the rigid and flexible wheels is also studied. The results show that the contact pressure uniformity of the flexible road wheel is better than that of the rigid road wheel under the static vertical load, but the maximum stress and deformation of the flexible road wheel are greater than that of the rigid road wheel. However, this problem can be solved by increasing the number of hinge sets and optimising the joints. The research results provide theoretical basis for replacing rigid road wheel with flexible road wheel, and also provide reference for structural optimisation of flexible road wheel
Spatial Distribution of Mass and Speed on Movement of Two Shrapnel Discs of Variable Thickness in Explosive Load
Get PDFResults of studies of the explosive expansion of a set of shrapnel discs of natural crushing are described in the article. Set consisted of two disks of different thickness, but of a fixed total mass. The studies were carried out by computer simulation of shock-wave processes in a continuous formulation using the ANSYS/LS-DYNA program. The program of computer design foresees development of three-dimensional certainly-element model including, in accordance with symmetry of the examined system fourth part of the examined explosive system of casting block, with imposed on its knots of the proper scopes terms concerted with taken mixed Lagrangian-Eulerian approach within the framework of the continuum model. The effect of the order of installing disks of different thickness on the distribution of their mass and its velocity in the middle of the meridional angle of expansion is established. The analysis of the computer simulation presented on the basis of numerical studies on the distribution of the mass of the disks and its velocity of motion suggests that to create a narrow high-speed uniformly filled fragmentary mass of the axial flow, it is necessary to change the geometric shape of the disc so that in the central angular zones of the disks. This allows the velocity of the fragment mass to be aligned along the radius of the discs and to fill the first angular zones with the required mass of fragments