A Proposed Test of Charge Symmetry in Σ\Sigma Decay

The semi-leptonic decays of $\Sigma^\pm$ offer a vehicle for observing charge symmetry-breaking. The effect is expected to be about 6\%, enhanced due to the replacement of two u quarks by d quarks. We propose that present experimental data be improved to search for this effect.Comment: 6 pages, submitted to Physical Review D, Brief Reports, Report # DOE/ER/40427-14-N9

Energy Efficiency Improvement Systems with Pneumatic Chamber Pump

We have proposed a new construction the pump chamber. We have carried out development of a mathematical model of the pump work chamber. On the basis of mathematical modeling we have proved the efficiency of applied design solutions. Adopted by the us constructive solutions to will improve the performance of the pump chamber by 2.34 times

Energy Efficiency Improvement Systems with Pneumatic Chamber Pump

We have proposed a new construction the pump chamber. We have carried out development of a mathematical model of the pump work chamber. On the basis of mathematical modeling we have proved the efficiency of applied design solutions. Adopted by the us constructive solutions to will improve the performance of the pump chamber by 2.34 times

Navier–Stokes and direct Monte-Carlo simulations of the circumnuclear gas coma III. Spherical, inhomogeneous sources

We pursue our program of comparative simulations of the cometary gas coma by the two most advanced techniques available: (1) numerical solution of Navier–Stokes equations coupled to the Boltzman equation in the surface boundary layer, and (2) direct Monte-Carlo simulation. Here, we consider two different spherical but compositionally inhomogeneous nuclei, at three very different levels of gas production. The results show the same excellent agreement between the two methods in a domain adjacent to the surface as found precedingly, practically down to free-molecular conditions. A wealth of coma density patterns with non-intuitive structure is obtained. Some of these structures appear even under free-molecular effusion from the surface. The physical origin of all structures is discussed, and their evolution with changing gas production is studied. The computed comae are compared to those computed by various authors precedingly. Intercomparison of the present results demonstrates that differing inhomogeneity patterns may lead to similar structures in the gas coma. Comparison between these structures and those created by homogeneous, aspherical surfaces shows that it is not possible to guess from empirical rules which one of the two processes is responsible for the creation of a given structure. The implications for the interpretation of future high resolution images, or of future in situ mass spectrometric samplings of the near-nucleus gas coma are discussed

Monte-Carlo and multifluid modelling of the circumnuclear dust coma II. Aspherical-homogeneous, and spherical-inhomogeneous nuclei

International audienceWe use our newly developed Dust Monte-Carlo (DMC) simulation technique (Crifo et al., 2005a) to study the dynamics of dust grains in the vicinity of some of the benchmark aspherical, homogeneous cometary nuclei and of the benchmark spherical, inhomogeneous nuclei studied by us precedingly. We use the interim unrealistic simplifying assumptions of grain sphericity, negligible nucleus rotation rate, and negligible tidal force, but take accurately into account the nucleus gravitational force, gas coma aerodynamic force, and solar radiation pressure force, and consider the full mass range of ejectable spherical grains. The resulting complicated grain motions are described in detail, as well as the resulting complicated and often counter-intuitive dust coma structure. The results are used to answer several important questions: (1) When computing coma dust distributions, (a) is it acceptable to take into consideration only one or two of the above mentioned forces (as currently done)? (b) to which accuracy must these forces be known, in particular is it acceptable to represent the gravity of an aspherical nucleus by a spherically symmetric gravity? (c) how do the more efficient but less general Dust Multi-Fluid (DMF) computations compare with the DMC results? (2) Are there simple structural relationships between the dust coma of a nucleus at small heliocentric distance , and that of the same nucleus at large ? (3) Are there similarities between the gas coma structures and the associated dust coma structures? (4) Are there dust coma signatures revealing non-ambiguously a spherical nucleus inhomogeneity or an homogeneous nucleus asphericity? (5) What are the implications of the apparently quite general process of grain fall-backs for the evolution of the nucleus surface, and for the survival of a landed probe

The prediction of the gas environment of the PHILAE probe during its 2014 descent to the nucleus of the comet 67P

International audienceOne of the objectives of the ESA ”ROSETTA” mission to the comet 67P was to insert, in August 2014, an orbiter probe around the so-called nucleus of the comet, and to deposit the ”PHILAE” lander at the surface of the nucleus in November 2014. The selection of the landing site and the definition of the release point and initial descent velocity vector were made in the period August to October 2014 on the basis of simulations of the descent trajectory. This requested an assessment of the gravitational and aerodynamic forces on PHILAE. We here describe the so-called RZC model developed to predict the gas environment of 67P in November 2014 and compute the aerodynamic force. We first outline the unusual diffculties resulting from (1) the complexity of the nucleus surface on all scales, (2) the absence of direct measurements of the gas flux at the surface itself, (3) the time-dependence of the gas production induced by the fast nucleus rotation, (4) the need to perform the whole program within less than three months. Then we outline the physical approach adopted to overcome these diffculties, and describe the RZC model which included three differing tools: (1) a set of gasdynamic/gaskinetic codes to compute the vacuum outflow of a rarefied gas mixture from a highly aspherical rotating solid source; (2) an heuristic approach to deal with the solid/gas initial boundary conditions, and (3) an iterative procedure to derive the gas production parameters on the nucleus surface from the observational data acquired from the orbiter probe. The satisfactory operation of the RZC code in the weeks preceding the November 2014 PHILAE descent is shown, and the forecasted aerodynamic force during the PHILAE descent is compared to the gravitational force

Energy Efficiency Improvement Systems with Pneumatic Chamber Pump

We have proposed a new construction the pump chamber. We have carried out development of a mathematical model of the pump work chamber. On the basis of mathematical modeling we have proved the efficiency of applied design solutions. Adopted by the us constructive solutions to will improve the performance of the pump chamber by 2.34 times