Design and Development of Redeployable Underwater Data Communication Link for Defence Application

Testing of underwater system for defence application is carried out from submersible platform at specified depth. The underwater platform houses the article under test, equipment and instruments required to conduct the test and to control the platform. During development phase of defence systems, large numbers of sensors are mounted on the test article and data is collected to validate the design. Data acquisition system, video camera and high speed video cameras are positioned on the platform to record physical parameters and observe visually the performance of the article under evaluation. Since the data and video signals are parallely recorded on ship, the bandwidth demand for real-time data communication from underwater platform to control station is very high. The existing technology presently used for underwater communication has limitation of bandwidth and not suitable for defence application. This paper describes in detail the design and development of a re-deployable data communication link by laying a specially designed negatively buoyant fibre optic cable in high-sea from ship to underwater platform to provide higher bandwidth required for defence application. The link has been successfully used for sea state less than one during evaluation of underwater defence system. The availability of bandwidth from underwater platform to control system can be increased significantly by laying fibre optic cable in high sea. It also provides unlimited bandwidth for the above requirement.

Emerging Trends in Instrumentation in Rocket Motor Testing

Rocket motors are designed, developed, and evaluated for performance, and after repeated tests, are qualified for use in a spacecraft or missile system. Comprehensive instrumentation measurement plan is made to record physical parameters during evaluation and testing. In the last thirty years, a revolution has happened in the field of electronics that has benefited instrumentation in terms of accuracy, bandwidth, capacity, reliability and analysis. This paper describes the improvements in instrumentation that have happened in the field of rocket motor testing over a period of last three decades.Defence Science Journal, Vol. 65, No. 1, January 2015, pp.63-69, DOI:http://dx.doi.org/10.14429/dsj.65.794

Design and Development of Power Management System of Unmanned Underwater Platform for Defence Application

Development of underwater weapon systems for defence application are carried out on unmanned underwater platform. Extensive testing and measurement of physical parameters are carried out during development phase trials. After several trials, system is qualified and installed on the actual platform. Mostly battery bank is used to power the unmanned platform. Design and development of power management system is an important issue of underwater platform to increase the underwater time of the platform. During development trials some additional equipments are also included for which power requirement was not considered during design of battery bank. This also becomes an issue to manage the power requirement of additional equipment beyond the design capability of the battery bank. Unmanned submersible platforms at a depth of 50 m to 70 m are used during development of underwater missile. Platform houses the missile to be tested, equipment required for missile launch and control of the platform. A power management system (PMS) with redundancy and fault tolerant features achieving reliability figure of 99 per cent has been designed, developed and tested successfully for underwater phase of missile launch. The system allows remote operation of individual or group of equipment, current monitoring, and isolation of faulty equipment. Power requirement for additional equipment on platform is also included in PMS without affecting the reliability of the system. Power control of equipment on requirement basis to save battery power, to increase underwater time of platform and to manage additional power requirement beyond the designed capacity of the battery bank is described in detail

Ferromagnetic Behavior in Zinc Ferrite Nanoparticles Synthesized using Coprecipitation Technique

Zinc ferrite have been produced and used by humans since long time, however understanding of ZnFe2O4 as a nano structured materials is very useful in order to be used for technological applications. ZnFe2O4 structural, magnetic and electrical properties are different when synthesized using different techniques. Therefore, it would be interesting to investigate the structural and magnetic properties of ZnFe2O4 when in nanosize. In the present work nanocrystalline ZnFe2O4 was synthesized using coprecipitation technique. The structural and magnetic properties of ZnFe2O4 nanopowders were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), dynamic light scattering (DLS), infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM). The XRD of ZnFe2O4 nanoparticles showed the single phase spinel structure. The average particle size of ZnFe2O4 calculated from XRD was observed to be 45 nm. DLS measurements showed the average particle size to be 42 nm. Further, the phase formation of ZnFe2O4 was confirmed from the IR measurements. The IR spectra showed the bands corresponding to ZnFe2O4. We observed the room temperature ferromagnetic behavior in synthesized ZnFe2O4 nanoparticles which may be due to the random distribution of Zn2+ and Fe3+ at the tetrahedral (A) and octahedral [B] sites. In our future work, we want to investigate the defect induced magnetic properties of ZnFe2O4 nanoparticles which is likely to contribute for ferromagnetic behavior in this material

Activation of Acetyl-CoA Carboxylase by a Glutamate- and Magnesium-Sensitive Protein Phosphatase in the Islet β-Cell

Acetyl-CoA carboxylase (ACC) catalyzes the formation of malonyl-CoA, a precursor in the biosynthesis of long-chain fatty acids, which have been implicated in physiological insulin secretion. The catalytic function of ACC is regulated by phosphorylation (inactive)−dephosphorylation (active). In this study we investigated whether similar regulatory mechanisms exist for ACC in the pancreatic islet β-cell. ACC was quantitated in normal rat islets, human islets, and clonal β-cells (HIT-15 or INS-1) using a [ 14 C]bicarbonate fixation assay. In the β-cell lysates, ACC was stimulated by magnesium in a concentration-dependent manner. Of all the dicarboxylic acids tested, only glutamate, albeit ineffective by itself, significantly potentiated magnesium-activated ACC in a concentration-dependent manner. ACC stimulation by glutamate and magnesium was maximally demonstrable in the cytosolic fraction; it was markedly reduced by okadaic acid (OKA) in concentrations

A Suggestive Diagnostic Technique For Early Identification Of Acyanotic Heart Disorders From Infant’s Cry

Congenital Heart Defects (CHD) are the critical heart disorders that can be observed at the birth stage of the infants. These are classified mainly into two, Cyanotic and Acyanotic. The present paper concentrates on the Acyanotic heart disorders. Acyanotic heart disorder cannot be observed on external checkup, whereas bluish skin is the indication for the infant affected with Cyanotic disorder. Acyanotic heart disorder can only be diagnosed using chest X-Ray, ECG, Echocardiogram, Cardiac Catheterization and MRI of the Heart. The present work aims at estimating the fundamental frequency (pitch) and the vocal tract resonant frequencies (formants) from the cry signal of the infants. The pitch frequency and formant frequencies are estimated using frequency domain (Cepstrum) and Linear Prediction Code (LPC) methods. The results show that the fundamental frequency of the cry signal was between 600Hz-800Hz for the infants with Acyanotic heart disorders. This fundamental frequency helps in identifying Acyanotic heart disorders at an early stage

Investigation of VBLAST Equalization Technique for Underwater Acoustic Communications

Underwater Acoustic Communications (UWAC) is an emerging technology in the field of underwater communications, and it is challenging because of the signal attenuation of the sound waves. Multiple Input and Multiple-Output (MIMO) is introduced in UWAC because of its support in enhancing the data throughput even under the conditions of interference, signal fading, and multipath. The paper presents the concept and analysis of 2× 2 MIMO UWAC systems that uses a 4- QAM spatial modulation scheme thus minimizing the decoding complexity and overcoming the Inter Channel Interference (IChI). Bit Error Rate (BER) investigation is carried out over different link distances under acoustic Line of Sight (LOS). The utilization of Zero Forcing (ZF) and Vertical-Bell Laboratories Layered Space-Time (VBLAST) equalizers, which estimates the transmitted data proves a success of removing Inter Symbol Interference (ISI).  The ISI caused due to multipath effect and scattering in UWAC can be reduced by iterative process considered in VBLAST.  A study is made on how the distance between the transmitter and the receiver and the Doppler Effect has its impact on the performance of the system

Air Quality Modeling for the Urban Jackson, Mississippi Region Using a High Resolution WRF/Chem Model

In this study, an attempt was made to simulate the air quality with reference to ozone over the Jackson (Mississippi) region using an online WRF/Chem (Weather Research and Forecasting–Chemistry) model. The WRF/Chem model has the advantages of the integration of the meteorological and chemistry modules with the same computational grid and same physical parameterizations and includes the feedback between the atmospheric chemistry and physical processes. The model was designed to have three nested domains with the inner-most domain covering the study region with a resolution of 1 km. The model was integrated for 48 hours continuously starting from 0000 UTC of 6 June 2006 and the evolution of surface ozone and other precursor pollutants were analyzed. The model simulated atmospheric flow fields and distributions of NO2 and O3 were evaluated for each of the three different time periods. The GIS based spatial distribution maps for ozone, its precursors NO, NO2, CO and HONO and the back trajectories indicate that all the mobile sources in Jackson, Ridgeland and Madison contributing significantly for their formation. The present study demonstrates the applicability of WRF/Chem model to generate quantitative information at high spatial and temporal resolution for the development of decision support systems for air quality regulatory agencies and health administrators

Simulation of Surface Ozone Pollution in the Central Gulf Coast Region Using WRF/Chem Model: Sensitivity to PBL and Land Surface Physics

The fully coupled WRF/Chem (Weather Research and Forecasting/Chemistry) model is used to simulate air quality in the Mississippi Gulf coastal region at a high resolution (4 km) for a moderately severe summer ozone episode between 18 CST 7 and 18 CST 10 June 2006. The model sensitivity is studied for meteorological and gaseous criteria pollutants (O3, NO2) using three Planetary Boundary Layer (PBL) and four land surface model (LSM) schemes and comparison of model results with monitoring station observations. Results indicated that a few combinations of PBL and LSMs could reasonably produce realistic meteorological fields and that the combination of Yonsei University (YSU) PBL and NOAH LSM provides best predictions for winds, temperature, humidity and mixed layer depth in the study region for the period of study. The diurnal range in ozone concentration is better estimated by the YSU PBL in association with either 5-layer or NOAH land surface model. The model seems to underestimate the ozone concentrations in the study domain because of underestimation of temperatures and overestimation of winds. The underestimation of NO2 by model suggests the necessity of examining the emission data in respect of its accurate representation at model resolution. Quantitative analysis for most monitoring stations indicates that the combination of YSU PBL with NOAH LSM provides the best results for various chemical species with minimum BIAS, RMSE, and high correlation values

Halogenated organic compounds in archived whale oil : a pre-industrial record

Author Posting. © The Authors, 2006. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Environmental Pollution 145 (2007): 668-671, doi:10.1016/j.envpol.2006.08.022.To provide additional evidence that several halogenated organic compounds (HOCs) found in environmental samples are natural and not industrially produced, we analyzed an archived whale oil sample collected in 1921 from the last voyage of the whaling ship Charles W. Morgan. This sample, which predates large-scale industrial manufacture of HOCs, contained two methoxylated polybrominated diphenyl ethers (MeO-PBDEs), five halogenated methyl bipyrroles (MBPs), one halogenated dimethyl bipyrrole (DMBP), and one dimethoxylated polybrominated biphenyl (diMeO-PBB). This result indicates, at least in part, a natural source of the latter compounds. Capsule Nine halogenated organic compounds have been detected in archived whale oil from the 1920s.This work was supported by the National Science Foundation (OCE-0221181 and OCE-0550486), the Woods Hole Oceanographic Institution (WHOI) Ocean Life Institute and the Postdoctoral Scholar Program at WHOI (with funding from The Camille and Henry Dreyfus Foundation, Inc. and The J. Seward Johnson Fund)