Advanced Navigation System for Aircraft Applications

Various forms of navigation are present in today’s world, leading from satellite based navigation to several archaic forms of navigation like star gazing. Now, lots of technologies are available to achieve this but with certain limitations. For example, FOG based navigation provides accuracy with in 0.10-100 range which is not sufficient for various military applications. Therefore, there is a need to design a system which will have better accuracy and thus requires development of ring laser gyro-based inertial systems. This paper concentrates on the aided navigation system based on ring laser gyro of 0.01 deg/hr class and GPS - GLONASS to further enhance the capability of system in terms of accuracy. The usage of such systems not only provides accurate results momentarily but it also persists for longer duration with the aid of GPS - GLONASS for applications like aircraft, ship and long range missiles. The system provides accuracy of the level of 1 Nm/hr in pure navigation and 30 m with the aid of GPS - GLONASS. Apart from this, the availability of gyro-compass and baro-inertial algorithms further enhances the system capabilities and made them self dependent to the major extent.Defence Science Journal, 2013, 63(2), pp.131-137, DOI:http://dx.doi.org/10.14429/dsj.63.425

The Journey of Building Defence Technological Capability

57-62Starting from the design of simple equipment to the development of the most advanced systems DRDO has continued its quest for indigenous defence systems development

USING MINIMAL LOAD POWER OBSERVER TO OPTIMIZE SYSTEM COST AND RELIABILITY

The previous term is made to result in the system errors converge to zero, whereas the second term is used to pay for those system uncertainties. Furthermore, the perfect load current observer can be used to optimize sys-tem cost and reliability. Particularly, the closed-loop stability of the observer-based optimal current control law is in past statistics proven by showing the whole states from the augmented observer-based control system errors tremendously converge to zero. This paper proposes an easy optimal current control way of three-phase uninterruptible-power-sup-ply systems. The suggested current controller consists of a feedback control term along with a paying control term. Unlike previous algorithms, the suggested method can produce a tradeoff between control input magnitude and tracking error simply by selecting proper performance indexes. The potency of the suggested controller is validated through simulations on MATLAB/Simulink and experiments on the prototype 600-Veterans administration test bed having a TMS320LF28335 DSP. Finally, the comparative recent results for the suggested plan and also the conventional feedback linearization control plan are given to show the suggested formula achieves a great performance for example fast transient response, small steady-condition error, and occasional total harmonic distortion under load step change, unbalanced load, and nonlinear load using the parameter variations

Maritime Aerosol Network as a component of Aerosol Robotic Network

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 114 (2009): D06204, doi:10.1029/2008JD011257.The paper presents the current status of the Maritime Aerosol Network (MAN), which has been developed as a component of the Aerosol Robotic Network (AERONET). MAN deploys Microtops handheld Sun photometers and utilizes the calibration procedure and data processing (Version 2) traceable to AERONET. A web site dedicated to the MAN activity is described. A brief historical perspective is given to aerosol optical depth (AOD) measurements over the oceans. A short summary of the existing data, collected on board ships of opportunity during the NASA Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project is presented. Globally averaged oceanic aerosol optical depth (derived from island-based AERONET measurements) at 500 nm is ∼0.11 and Angstrom parameter (computed within spectral range 440–870 nm) is calculated to be ∼0.6. First results from the cruises contributing to the Maritime Aerosol Network are shown. MAN ship-based aerosol optical depth compares well to simultaneous island and near-coastal AERONET site AOD.The work of Tymon Zielinski was supported by Polish national grant AERONET59

Distinct Salmonella Enteritidis lineages associated with enterocolitis in high-income settings and invasive disease in low-income settings.

An epidemiological paradox surrounds Salmonella enterica serovar Enteritidis. In high-income settings, it has been responsible for an epidemic of poultry-associated, self-limiting enterocolitis, whereas in sub-Saharan Africa it is a major cause of invasive nontyphoidal Salmonella disease, associated with high case fatality. By whole-genome sequence analysis of 675 isolates of S. Enteritidis from 45 countries, we show the existence of a global epidemic clade and two new clades of S. Enteritidis that are geographically restricted to distinct regions of Africa. The African isolates display genomic degradation, a novel prophage repertoire, and an expanded multidrug resistance plasmid. S. Enteritidis is a further example of a Salmonella serotype that displays niche plasticity, with distinct clades that enable it to become a prominent cause of gastroenteritis in association with the industrial production of eggs and of multidrug-resistant, bloodstream-invasive infection in Africa.This work was supported by the Wellcome Trust. We would like to thank the members of the Pathogen Informatics Team and the core sequencing teams at the Wellcome Trust Sanger Institute (Cambridge, UK). We are grateful to D. Harris for work in managing the sequence data

High speed schlieren facility for visualization of flow fields in hypersonic shock tunnels

The time-dependent evolution of flow around a 120° blunt cone model with a base radius of 60 mm has been visualized at Mach 8.8 and 9.2 using the newly established high speed schlieren facility in the IISc hypersonic shock tunnel HST2. The establishment and termination process of hypersonic flow in the shock tunnel is visualized using both argon and air as test gases. The experimental shock stand-off distance around the blunt cone matches well with the results from the computational fluid dynamics study

Experimental Investigation on Radial Ball Bearing Parameters Using Taguchi Method

In this work, characteristics of various ball bearing parameters are studied under different loads and rotational speeds. By using Dimensional Analysis (DA), dimensionless parameters are computed which provides solution for a group of parameters. This analysis can be accomplished by using the Buckingham π-theorem. DA leads to reduction of the number of independent parameters involved in a problem. These independent parameters get expressed as dimensionless groups. These dimensionless groups are always ratios of important physical quantities involved in the problem of interest. In modeling and experimentation, its main function is to reduce the amount of independent variables, simplify the solution, and generalize the results. It becomes an effective method, especially if a complete mathematical model of the investigated process is not known. Moreover, in the present work the Buckingham π-theorem is applied to find the influencing parameter π5 by using the Taguchi method

Montmorillonite clay catalyzed alkylation of pyrroles and indoles with cyclic hemi-acetals

Cyclic hemiacetals such as 2-deoxy-D-ribose and 2-deoxy-D-glucose react smoothly with pyrroles and indoles on the surface of montmorillonite KSF clay under extremely mild reaction conditions to afford optically active di-pyrrolyl and bis-indolyl alkanols in good yields with high selectivity

Bi(OTf)<SUB>3</SUB>-catalyzed allylation of epoxides: a facile synthesis of homoallylic alcohols

Epoxides react smoothly with tetraallyltin in the presence of 2 mol% of Bi(OTf)3 under mild reaction conditions to afford the corresponding homoallylic alcohols in excellent yields with high regioselectivity while aryl aziridines produce exclusively allyl amines in good yields under similar conditions