The Design and Research of a New Low Cobalt-molybdenum Niobium-containing Ni-base Superalloy for 700 ̊C Advanced Ultra-supercritical Power Plants

AbstractA new Ni-base Nb-containing supealloy of low Co-Mo, Ni-24Cr-16(Co+Mo+W)-4.5(Nb+Ti+Al)-0.03C (wt. %), was designed for 700°C advanced ultra-super-critical power plant application, and the boiler superheater/reheater tubes were successfully manufactured. The alloy design was conducted by thermodynamics and dynamics calculation using Thermal-Calc and JmatPro commercial software. The microstructural stability of the new alloy was evaluated by FESEM and TEM. The mechanical properties, such as microhardness and impact toughness at room temperature, were also tested. The calculation results show that molybdenum promotes the formation of σ and μ phase obviously and cobalt promotes the formation of η, σ, and μ simultaneously. In addition, high molybdenum content will decrease the flue gas ash corrosion resistance and cobalt is a kind of strategic resource in the world. Therefore, the concept of “low Co-Mo Ni-base superalloy” was determined. The implementation of “Low Co-Mo” can reduce cost, restrain the formation of harmful phases as well as ensure good oxidation/corrosion resistance on the basis of high Cr content. To optimize the new alloy, both the combined solid solution strengthening of Cr-Co-Mo-W and the precipitation strengthening elements Nb, Ti and Al are adopted, because Nb is a good γ’-strengthening element in combination with Ti and Al for Ni-base superalloy. The experimental results of SEM and TEM show that no harmful phases precipitate after 1000 h-aging at 760°C and 800°C, and the γ′ coarsening rate is low, which reveals a good microstructure stability of this new alloy

Action Principle for the Classical Dual Electrodynamics

The purpose of this paper is to formulate an action principle which allows for the construction of a classical lagrangean including both electric and magnetic currents. The lagrangean is non-local and shown to yield all the expected (local) equations for dual electrodynamics.Comment: latex, 8 pages, no figure

Control of a Movable Robot Head Using Vision-Based Object Tracking

This paper presents a visual tracking system to support the movement of the robot head for detecting the existence of objects. Object identification and object position estimation were conducted using image-based processing. The movement of the robot head was in four directions namely  to the right, left, top, and bottom of the robot head. Based on the distance of the object, it shifted the object to many points to assess the accuracy of the process of tracking the object. The targeted objects are detected through several processes, namely normalization of RGB images, thresholding, and object marking. The process of tracking the object conducted by the robot head varied in 40 various object points with high accuracy. The further the object’s distance to the robot, the smaller the corner of the movement of the robot produced compared to the movement of the robot head to track an object that was closer even though with the same distance stimulant shift object. However, for the distance and the shift of the same object, the level of accuracy showed almost the same results. The results showed the movement of the robot head to track the object under the head of the robot produced the movement with a larger angular error compared to the movement of the robot head in another direction even though with the stimulant distance of the same object position and the distance shift of the same object

Constraints on coupling constant between dark energy and dark matter

We have investigated constraints on the coupling between dark matter and the interacting Chaplygin gas. Our results indicate that the coupling constant $c$ between these two entities can take arbitrary values, which can be either positive or negative, thus giving arbitrary freedom to the inter-conversion between Chaplygin gas and dark matter. Thus our results indicate that the restriction $0<c<1$ on the coupling constant occurs as a very special case. Our analysis also supports the existence of phantom energy under certain conditions on the coupling constant.Comment: 16 Pages, 3 figure

Hydrodynamic Synchronisation of Model Microswimmers

We define a model microswimmer with a variable cycle time, thus allowing the possibility of phase locking driven by hydrodynamic interactions between swimmers. We find that, for extensile or contractile swimmers, phase locking does occur, with the relative phase of the two swimmers being, in general, close to 0 or pi, depending on their relative position and orientation. We show that, as expected on grounds of symmetry, self T-dual swimmers, which are time-reversal covariant, do not phase-lock. We also discuss the phase behaviour of a line of tethered swimmers, or pumps. These show oscillations in their relative phases reminiscent of the metachronal waves of cilia.Comment: 17 pages, 8 figure

The generalized second law for the interacting generalized Chaplygin gas model

We investigate the validity of the generalized second law (GSL) of gravitational thermodynamics in a non-flat FRW universe containing the interacting generalized Chaplygin gas with the baryonic matter. The dynamical apparent horizon is assumed to be the boundary of the universe. We show that for the interacting generalized Chaplygin gas as a unified candidate for dark matter (DM) and dark energy (DE), the equation of state parameter can cross the phantom divide. We also present that for the selected model under thermal equilibrium with the Hawking radiation, the GSL is always satisfied throughout the history of the universe for any spatial curvature, independently of the equation of state of the interacting generalized Chaplygin gas model.Comment: 8 page

Graviton plus vector boson production to NLO in QCD at the LHC

We present the next-to-leading order QCD corrections to the associated production of the vector gauge boson ($Z/W^\pm$) and the graviton in the large extra dimension model at the LHC. We estimate the impact of the QCD corrections on the total cross sections as well as the differential distributions of the gauge bosons and find that they are significant. We also study the dependence of the cross sections on the arbitrary factorization scale and show the reduction in the scale uncertainties at NLO level. Further, we discuss the ultraviolet sensitivity of the theoretical predictions.Comment: 51 pages and 27 figure

Towards the characterization of individual users through Web analytics

We perform an analysis of the way individual users navigate in the Web. We focus primarily in the temporal patterns of they return to a given page. The return probability as a function of time as well as the distribution of time intervals between consecutive visits are measured and found to be independent of the level of activity of single users. The results indicate a rich variety of individual behaviors and seem to preclude the possibility of defining a characteristic frequency for each user in his/her visits to a single site.Comment: 8 pages, 4 figures. To appear in Proceeding of Complex'0

Frequency-dependent magnetotransport and particle dynamics in magnetic modulation systems

We analyze the dynamics of a charged particle moving in the presence of spatially-modulated magnetic fields. From Poincare surfaces of section and Liapunov exponents for characteristic trajectories we find that the fraction of pinned and runaway quasiperiodic orbits {\em vs}. chaotic orbits depends strongly on the ratio of cyclotron radius to the structure parameters, as well as on the amplitude of the modulated field. We present a complete characterization of the dynamical behavior of such structures, and investigate the contribution to the magnetoconductivity from all different orbits using a classical Kubo formula. Although the DC conductivity of the system depends strongly on the pinned and runaway trajectories, the frequency response reflects the topology of all different orbits, and even their unusual temporal behavior.Comment: Submitted to PRB - 14 figure files - REVTEX tex