Geometric dimensioning and tolerancing a tool for concurrent engineering

The concept of Concurrent Engineering recognizes an immediate need for a new design environment and technology and so requires extensive interdisciplinary cooperation and integration of diverse functions of a manufacturing organization such as marketing, design, manufacturing and finance. One of the key factors to achieve successful integration among the departments is better communication and it becomes imperative in cases of varying levels of communication needs, especially in interdepartmental cases. Concurrent Engineering is a philosophy which provides certain benefits. There are various tools and methods available for implementation of Concurrent Engineering concepts. One of the tools is Geometric Dimensioning & Tolerancing (GD & T), which can be used for indespensible communication of exact part design and its proper execution. Unlike other tools, GD & T concepts emphasize on the integration of various functions in a manufacturing organization. This thesis discusses the applicability of Geometric Dimensioning and Tol-erancing as an integrating tool for related functional departments in the concurrent environment. It also establishes the synchronization between the objectives of the two concepts. Also, it discusses the effect of using GD & T on vendor lead time and manufacturing lead time. The effect on the product quality, the cost economics and the learning curve is also investigated. Lastly, the thesis concludes that the implementation of GD & T concepts automatically attains the objectives of concurrent engineering. The use of GD & T in industries may lead to widespread implementation of the concurrent engineering concepts globally. Therefore, it can be considered as a medium or tool for Concurrent Engineering

Perturbations on steady spherical accretion in Schwarzschild geometry

The stationary background flow in the spherically symmetric infall of a compressible fluid, coupled to the space-time defined by the static Schwarzschild metric, has been subjected to linearized perturbations. The perturbative procedure is based on the continuity condition and it shows that the coupling of the flow with the geometry of space-time brings about greater stability for the flow, to the extent that the amplitude of the perturbation, treated as a standing wave, decays in time, as opposed to the amplitude remaining constant in the Newtonian limit. In qualitative terms this situation simulates the effect of a dissipative mechanism in the classical Bondi accretion flow, defined in the Newtonian construct of space and time. As a result of this approach it becomes impossible to define an acoustic metric for a conserved spherically symmetric flow, described within the framework of Schwarzschild geometry. In keeping with this view, the perturbation, considered separately as a high-frequency travelling wave, also has its amplitude reduced.Comment: 8 pages, no figur

Photonuclear reactions of actinides in the giant dipole resonance region

Photonuclear reactions at energies covering the giant dipole resonance (GDR) region are analyzed with an approach based on nuclear photoabsorption followed by the process of competition between light particle evaporation and fission for the excited nucleus. The photoabsorption cross section at energies covering the GDR region is contributed by both the Lorentz type GDR cross section and the quasideuteron cross section. The evaporation-fission process of the compound nucleus is simulated in a Monte-Carlo framework. Photofission reaction cross sections are analyzed in a systematic manner in the energy range of $\sim$ 10-20 MeV for the actinides $^{232}$Th, $^{238}$U and $^{237}$Np. Photonuclear cross sections for the medium-mass nuclei $^{63}$Cu and $^{64}$Zn, for which there are no fission events, are also presented. The study reproduces satisfactorily the available experimental data of photofission cross sections at GDR energy region and the increasing trend of nuclear fissility with the fissility parameter $Z^2/A$ for the actinides.Comment: 4 pages including 2 tables and 1 figur

Physical properties of large cardamom cultivated in north eastern Himalayan region of Sikkim, India

The large cardamom is one of the most important spice crops grown in Himalayan region of Sikkim, India.  The capsules of the harvested large cardamom are dried before consumption.  The paper presents the physical properties of  freshly harvested and dried large cardamom capsules.  The geometrical mean diameter, sphericity, bulk density and mean values of angle of repose of the freshly harvested large cardamom capsules were observed to be 18.53±1.73 mm, 0.76, 332.21±14.24 kg m-3 and 28.74±4.04°, respectively.  Whereas for dried large cardamom capsules the values were found to be 11.113±0.92 mm, 0.56, 393.109±9.622 kg m-3 and 29.84±2.93°, respectively.  The peak static coefficient of friction of freshly harvested large cardamom over mild steel, plywood and plastic film surfaces were 0.386, 0.463 and 0.359, respectively.  However, for dried large cardamom capsules, the observed values were 0.436, 0.394 and 0.155, respectively.   Keywords: large cardamom, spice crop, physical propertie

Loss Allocation based on Network Reduction in Deregulated Electricity Market

Loss allocation of electricity has been in the limelight since the introduction of deregulation in the electricity market. For a fair and transparent market, method to allocate appropriate loss to any customer is necessary. This paper paper proposes an approximated loss allocation method based on network reduction. Reduction of the network is dependent upon bilateral contract between any one generator (seller)and one load (customer/buyer). Gaussian elemination is applied to reduce the bus admittance matrix of the network. The reduced network will contain only buses of primary interest - that is of the analysed contract. IEEE 14-bus test system is used to illustrate the proposed methodology. The results from this analysis are presented in this paper

Economic Constrained Transfer Capability Assessment

Following the deregulation of electric power utilities around the globe, it has been widely acknowledged that quantifying power system transfer capability is of increasingly importance in today's large-scale and interconnected power system operation and planning procedures. This paper introduces a novel framework to evaluate transfer capability incorporating electricity market dispatching considerations, which we termed it as economic constrained transfer capability (ETC) problem. A mathematical model of a multi-objective optimization (MOOP) approach is presented to solve this ETC problem. The proposed methodology has been tested on a classical 3-machine 9-bus system and the IEEE 30-bus system. Preliminary simulation results from several case studies are presented with relevant analyses and discussions

Magnetic Lattice Dynamics of the Oxygen-Free FeAs Pnictides: How Sensitive are Phonons to Magnetic Ordering?

To shed light on the role of magnetism on the superconducting mechanism of the oxygen-free FeAs pnictides, we investigate the effect of magnetic ordering on phonon dynamics in the low-temperature orthorhombic parent compounds, which present a spin-density wave. The study covers both the 122 (AFe2As2; A=Ca, Sr, Ba) and 1111 (AFeAsF; A=Ca, Sr) phases. We extend our recent work on the Ca (122 and 1111) and Ba (122) cases by treating computationally and experimentally the 122 and 1111 Sr compounds. The effect of magnetic ordering is investigated through detailed non-magnetic and magnetic lattice dynamical calculations. The comparison of the experimental and calculated phonon spectra shows that the magnetic interactions/ordering have to be included in order to reproduce well the measured density of states. This highlights a spin-correlated phonon behavior which is more pronounced than the apparently weak electron-phonon coupling estimated in these materials. Furthermore, there is no noticeable difference between phonon spectra of the 122 Ba and Sr, whereas there are substantial differences when comparing these to CaFe2As2 originating from different aspects of structure and bonding

Evolution of Fluctuation in relativistic heavy-ion collisions

We have studied the time evolution of the fluctuations in the net baryon number for different initial conditions and space time evolution scenarios. We observe that the fluctuations at the freeze-out depend crucially on the equation of state (EOS) of the system and for realistic EOS the initial fluctuation is substantially dissipated at the freeze-out stage. At SPS energies the fluctuations in net baryon number at the freeze-out stage for quark gluon plasma and hadronic initial state is close to the Poissonian noise for ideal as well as for EOS obtained by including heavier hadronic degrees of freedom. For EOS obtained from the parametrization of lattice QCD results the fluctuation is larger than Poissonian noise. It is also observed that at RHIC energies the fluctuations at the freeze-out point deviates from the Poissonian noise for ideal as well as realistic equation of state, indicating presence of dynamical fluctuations.Comment: 9 pages and 6 figures (Major modifications done

Heavy Ions: Results from the Large Hadron Collider

On November 8, 2010 the Large Hadron Collider (LHC) at CERN collided first stable beams of heavy ions (Pb on Pb) at center-of-mass energy of 2.76 TeV/nucleon. The LHC worked exceedingly well during its one month of operation with heavy ions, delivering about 10 microbarn-inverse of data, with peak luminosity reaching to $L_{0} = 2 \times 10^{25}{\rm cm}^{-2}{\rm s}^{-1}$ towards the end of the run. Three experiments, ALICE, ATLAS and CMS, recorded their first heavy ion data, which were analyzed in a record time. The results of the multiplicity, flow, fluctuations, and Bose-Einstein correlations indicate that the fireball formed in nuclear collisions at the LHC is hotter, lives longer, and expands to a larger size at freeze-out as compared to lower energies. We give an overview of these as well as new results on quarkonia and heavy flavour suppression, and jet energy loss.Comment: Proceedings of Lepton-Photon 2011 Conference, to be published in Pramana, Journal of Physics. 15 page