Conductance-based interface detection for multi-phase pipe flow

Sediment and flow depth monitoring in sewers is important for informing flow models and for predicting and mitigating against sewer blockage formation and surcharge. In this study, a novel sensor based on conductance measurement has been developed and tested under a laboratory environment and validated by a finite-element model. The relative conductance is measured between pairs of adjacent electrodes to provide a conductance profile along the sensor length. A piecewise linear relationship between conductance and electrode length was derived and the interface positions between sediment, water, and air can be determined from the profile. The results demonstrated that the root mean square error of the model and the measured interface level are within 1.4% and 2.6% of sensor’s measurement range. An error distribution of interface height shows that all anticipated errors are within the resolution of the electrode length increments. Furthermore, it was found that the conductivity of the measured medium is proportional to the gradient of the linear relationship of conductance and electrode length. It could therefore prove a valuable new tool for the accurate quantification of sediment and flow levels in sewer conduits, coastal environments, drainage systems for transport networks, and other industrial or academic applications

On the fraction of dark matter in charged massive particles (CHAMPs)

From various cosmological, astrophysical and terrestrial requirements, we derive conservative upper bounds on the present-day fraction of the mass of the Galactic dark matter (DM) halo in charged massive particles (CHAMPs). If dark matter particles are neutral but decay lately into CHAMPs, the lack of detection of heavy hydrogen in sea water and the vertical pressure equilibrium in the Galactic disc turn out to put the most stringent bounds. Adopting very conservative assumptions about the recoiling velocity of CHAMPs in the decay and on the decay energy deposited in baryonic gas, we find that the lifetime for decaying neutral DM must be > (0.9-3.4)x 10^3 Gyr. Even assuming the gyroradii of CHAMPs in the Galactic magnetic field are too small for halo CHAMPs to reach Earth, the present-day fraction of the mass of the Galactic halo in CHAMPs should be < (0.4-1.4)x 10^{-2}. We show that redistributing the DM through the coupling between CHAMPs and the ubiquitous magnetic fields cannot be a solution to the cuspy halo problem in dwarf galaxies.Comment: 21 pages, 2 figures. To appear in JCA

Radiative Mechanism to Light Fermion Masses in the MSSM

In a previous work we have showed that the ${\cal Z}_{2}^{\prime}$ Symmetry, imply that the light fermions, the electron and the quarks, $u,d$ and $s$, get their masses only at one loop level. Here, we considere the more general hypothesis for flavour mixing in the sfermion sector in the MSSM. Then, we present our results to the masses of these light fermions and as a final result we can explain why the $s$ quark is heavier than the $u,d$ quarks. This mechanism is in agrement with the experimental constraint on the sfermion's masses values.Comment: 22 pages, 8 figures, TeX mistakes corrected, accepted for publication in JHE

Nuclear muon capture by 3He: meson exchange currents for the triton channel

Exchange current corrections are calculated using currents found from the hard-pion model and AV14+3BF wavefunctions. Results are given for the rate and spin observables. Their sensitivity to g_P, the nucleon pseudoscalar form factor, is reported.Comment: 35 pages, uuencoded gz-compressed tar file 42 Kbyte

Consistent Treatment of Relativistic Effects in Electrodisintegration of the Deuteron

The influence of relativistic contributions to deuteron electrodisintegration is systematically studied in various kinematic regions of energy and momentum transfer. As theoretical framework the equation-of-motion and the unitarily equivalent S-matrix approaches are used. In a (p/M)-expansion, all leading order relativistic $\pi$-exchange contributions consistent with the Bonn OBEPQ model are included. In addition, static heavy meson exchange currents including boost terms, $\gamma\pi\rho/\omega$-currents, and $\Delta$-isobar contributions are considered. Sizeable effects from the various relativistic two-body contributions, mainly from $\pi$-exchange, have been found in inclusive form factors and exclusive structure functions for a variety of kinematic regions.Comment: 41 pages revtex including 15 postscript figure

Computer simulations of hard pear-shaped particles

We report results obtained from Monte Carlo simulations investi- gating mesophase formation in two model systems of hard pear-shaped particles. The first model considered is a hard variant of the trun- cated Stone-Expansion model previously shown to form nematic and smectic mesophases when embedded within a 12-6 Gay-Berne-like po- tential [1]. When stripped of its attractive interactions, however, this system is found to lose its liquid crystalline phases. For particles of length to breadth ratio k = 3, glassy behaviour is seen at high pressures, whereas for k = 5 several bi-layer-like domains are seen, with high intradomain order but little interdomain orientational correlation. For the second model, which uses a parametric shape parameter based on the generalised Gay-Berne formalism, results are presented for particles with elongation k = 3; 4 and 5. Here, the systems with k = 3 and 4 fail to display orientationally ordered phases, but that with k = 5 shows isotropic, nematic and, unusually for a hard-particle model, interdigitated smectic A2 phases.</p

Neutrino Oscillations and Collider Test of the R-parity Violating Minimal Supergravity Model

We study the R-parity violating minimal supergravity models accounting for the observed neutrino masses and mixing, which can be tested in future collider experiments. The bi-large mixing can be explained by allowing five dominant tri-linear couplings $\lambda'_{1,2,3}$ and $\lambda_{1,2}$. The desired ratio of the atmospheric and solar neutrino mass-squared differences can be obtained in a very limited parameter space where the tree-level contribution is tuned to be suppressed. In this allowed region, we quantify the correlation between the three neutrino mixing angles and the tri-linear R-parity violating couplings. Qualitatively, the relations $| \lambda'_1 | < | \lambda'_2| \sim | \lambda'_3|$, and $|\lambda_1| \sim |\lambda_2|$ are required by the large atmospheric neutrino mixing angle $\theta_{23}$ and the small angle $\theta_{13}$, and the large solar neutrino mixing angle $\theta_{12}$, respectively. Such a prediction on the couplings can be tested in the next linear colliders by observing the branching ratios of the lightest supersymmetric particle (LSP). For the stau or the neutralino LSP, the ratio $|\lambda_1|^2: |\lambda_2|^2: |\lambda_1|^2 + |\lambda_2|^2$ can be measured by establishing $Br(e\nu): Br(\mu\nu) : Br(\tau\nu)$ or $Br(\nu e^\pm \tau^\mp ): Br(\nu\mu^\pm\tau^\mp) : Br(\nu\tau^\pm\tau^\mp)$, respectively. The information on the couplings $\lambda'_i$ can be drawn by measuring $Br(l_i t \bar{b}) \propto |\lambda'_i|^2$ if the neutralino LSP is heavier than the top quark.Comment: RevTex, 25 pages, 8 eps figure