A novel Artificial Neural Network-based streamline tracing strategy applied to hypersonic waverider design

Streamline tracing in conical hypersonic flows is essential for designing high-performance waverider and intake. Conventionally, the streamline equations are solved after obtaining the velocity field from the solution of the axisymmetric conical flow field. The hypersonic waverider shape is generated from the base conical flow field by repeatedly applying the streamline tracing approach along several planes. When exploring the design space for optimization of the waverider, streamline tracing can be computationally expensive. We provide a novel strategy where first the Taylor-Maccoll equations for the inviscid axisymmetric conical flowfield and the streamlines from the shock are solved for a wide range of cone angle and Mach number conditions resulting in an extensive database. The streamlines are parametrized by a third-order polynomial, and an Artificial Neural Network (ANN) is trained to predict the coefficients of the polynomial for arbitrary inputs of Mach number, cone angle, and streamline originating location on the shock . We apply this strategy to design a cone derived waverider and compare the geometry obtained with the standard conical waverider design method and the simplified waverider design method. The ANN technique is highly accurate, with a difference of 0.68% with the standard in the coordinates of the waverider. RANS computations show that the ANN derived waverider does not indicate severe flow spillage at the leading edge, which is observed in the waverider generated from the simplified method. The new ANN-based approach is 20 times faster than the conventional method

Managing the natural disasters from space technology inputs

Natural disasters, whether of meteorological origin such as Cyclones, Floods, Tornadoes and Droughts or of having geological nature such as earthquakes and volcanoes, are well known for their devastating impacts on human life, economy and environment. With tropical climate and unstable land forms, coupled with high population density, poverty, illiteracy and lack of infrastructure development, developing countries are more vulnerable to suffer from the damaging potential of such disasters. Though it is almost impossible to completely neutralise the damage due to these disasters, it is, however possible to (i) minimise the potential risks by developing disaster early warning strategies (ii) prepare developmental plans to provide resilience to such disasters, (iii) mobilize resources including communication and telemedicinal services and (iv) to help in rehabilitation and post-disaster reconstruction. Space borne platforms have demonstrated their capability in efficient disaster management. While communication satellites help in disaster warning, relief mobilisation and telemedicinal support, Earth observation satellites provide the basic support in pre-disaster preparedness programmes, in-disaster response and monitoring activities, and post-disaster reconstruction. The paper examines the information requirements for disaster risk management, assess developing country capabilities for building the necessary decision support systems, and evaluate the role of satellite remote sensing. It describes several examples of initiatives from developing countries in their attempt to evolve a suitable strategy for disaster preparedness and operational framework for the disaster management Using remote sensing data in conjunction with other collateral information. It concludes with suggestions and recommendations to establish a worldwide network of necessary space and ground segments towards strengthening the technological capabilities for disaster management and mitigation

An indigenous cluster beam apparatus with a reflectron time-of-flight mass spectrometer

The design and fabrication of a Smalley-type cluster source in combination with a reflectron based time-of-flight (TOF) mass spectrometer are reported. The generation of clusters is based on supersonic jet expansion of the sampling plume. Sample cells for both liquid and solid targets developed for this purpose are described. Two pulsed Nd-YAG lasers are used in tandem, one (532 nm) for target vapourization and the other (355 nm) for cluster ionization. Methanol clusters of nuclearity up to 14 (mass 500 amu) were produced from liquid methanol as the test sample. The clusters were detected with a mass resolution of ~2500 in the R-TOF geometry. Carbon clusters up to a nuclearity of 28 were obtained using a polyimide target. The utility of the instrument is demonstrated by carrying out experiments to generate mixed clusters from alcohol mixtures

Bio-chemical basis in groundnut (Arachis hypogaea) resistant to leafminer (Aproaerema modicella)

A bio-chemical study was conducted to assess the role of different plant-chemical constituents using groundnut (Aeachis hypogaea L.) selections resistant ['ICG 5040','ICGS 2741','ICG (FDRS) 10','NC AC 17090' and 'GBPRS 312 (ICGV 86031),] and susceptible ('ICG 221', 'ICGS 44' and 'Robut 33-1 ') to leafminer [Aproaerema modicella (Deveuter)]. 'ICG 5040' and 'ICGS 2741' exuded more sap on 'injury than the other selections at 20 days after plant emergence under similar conditions. Bio-chemical analysis of complete plant-extracted sap at 50 days after plant emergence indicated that resistant selections particularly' ICG 5040' and 'GBPRS 312' contained higher quantities of soluble sugars, nitrogen (N) and polyphenols than the susceptible ones. Analysis of phenolic compouods of the sap samples through'high pressure liquid chromatography from top 2 open leaves 20 days aner plant emergence indicated that the concentration of these chemicals in the resistant selections was less than in the susceptible selection. However, resistant selections were able to exude more sap, compensating for the low concentration of phenolic compounds in the sa

Photoelectrochemical studies on the mixed oxides, A<SUB>6</SUB>Nb<SUB>8</SUB>Ti<SUB>2</SUB>O<SUB>30</SUB>(A=Ba,Sr)

The photoelectrochemical behaviour of oxide bronzes of the type A6Nb8Ti2O30 (A=Ba, Sr) has been studied. They show good photoactivity with photopotentials of the order of 700-800 mV. The flat band potential has been estimated to be -0&#183;9 V vs SCE. The band gap estimated from the spectral response is 3&#183;1 eV

Superconductivity behaviour of screen-printed LnBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7</SUB> (Ln=Eu,Y)films

Thick films of the high Tc superconducting oxides, LnBa2Cu3O7, Ln=Eu, Y, have been fabricated by screen printing on alumina and SrTiO3 substrates. Conditions for optimum superconductivity behaviour of the films have been established. Tconset varies from 90-94 K for all the films but zero resistance was observed only in a few cases

Quality engineering of a traction alternator by robust design

Robust design is an engineering methodology for improving productivity during research and development so that high-quality products can be developed and produced quickly and at low cost. A large electrical company was developing traction alternators for a diesel electrical engine. Customer requirement was to obtain very high efficiency which, in turn, was influenced by several design parameters. The usual approach of the 'design-build-test' cycle was considered time-consuming and costly; it used to take anywhere from 4 months to 1 year before finalizing the product design parameters as it involved physical assembly and also testing. Instead, the authors used Taguchi's parameter design approach. This approach took about 8 weeks to arrive at optimum design parameter values; clearly demonstrating the cutting edge of this methodology over the traditional design-build-test approach. The prototype built and tested accordingly gave satisfactory overall performance, meeting and even exceeding customer requirements

Relativistic Proton Production During the 14 July 2000 Solar Event: The Case for Multiple Source Mechanisms

Protons accelerated to relativistic energies by transient solar and interplanetary phenomena caused a ground-level cosmic ray enhancement on 14 July 2000, Bastille Day. Near-Earth spacecraft measured the proton flux directly and ground-based observatories measured the secondary responses to higher energy protons. We have modelled the arrival of these relativistic protons at Earth using a technique which deduces the spectrum, arrival direction and anisotropy of the high-energy protons that produce increased responses in neutron monitors. To investigate the acceleration processes involved we have employed theoretical shock and stochastic acceleration spectral forms in our fits to spacecraft and neutron monitor data. During the rising phase of the event (10:45 UT and 10:50 UT) we find that the spectrum between 140 MeV and 4 GeV is best fitted by a shock acceleration spectrum. In contrast, the spectrum at the peak (10:55 UT and 11:00 UT) and in the declining phase (11:40 UT) is best fitted with a stochastic acceleration spectrum. We propose that at least two acceleration processes were responsible for the production of relativistic protons during the Bastille Day solar event: (1) protons were accelerated to relativistic energies by a shock, presumably a coronal mass ejection (CME). (2) protons were also accelerated to relativistic energies by stochastic processes initiated by magnetohydrodynamic (MHD) turbulence.Comment: 38 pages, 9 figures, accepted for publication in the Astrophysical Journal, January, 200

From chiral vibration to static chirality in ^{135}Nd

Electromagnetic transition probabilities have been measured for the intra- and inter-band transitions in the two sequences in the nucleus ^{135}Nd that were previously identified as a composite chiral pair of rotational bands. The measurements are in good agreement with results of a new combination of TAC and RPA calculations. The chiral character of the bands is affirmed and it is shown that their behavior is associated with a transition from a vibrational into a static chiral regime.Comment: Accepted for publication in the Physical Review Letters. Small modifications to fit the length limits of the journal. 10 pages, 4 figure

Superconductivity studies on Tl-Th-Sr-Ca-Cu-O system

Superconductivity with a maximum Tc,zero of 58 K for x &gt; 0&#183;75 has been observed in a nominal starting composition, ThxTl2Sr2Ca2Cu3Oy. X-ray data show that the 1212 phase gets stabilized due to part substitution of Th at the Tl-site for x &#8805; 0&#183;25; however, Tc is low for x &lt; 0&#183;75