Gas sampling method for determining pollutant concentrations in the flame zone of two swirl-can combustor modules

A gas sampling probe and traversing mechanism were developed to obtain detailed measurements of gaseous pollutant concentrations in the primary and mixing regions of combustors in order to better understand how pollutants are formed. The gas sampling probe was actuated by a three-degree-of-freedom traversing mechanism and the samples obtained were analyzed by an on-line gas analysis system. The pollutants in the flame zone of two different swirl-can combustor modules were measured at an inlet-air temperature of 590 K, pressure of 6 atmospheres, and reference velocities of 23 and 30 meters per second at a fuel-air ratio of 0.02. Typical results show large spatial gradients in the gaseous pollutant concentration close to the swirl-can module. Average concentrations of unburned hydrocarbons and carbon monoxide decrease rapidly in the downstream wake regions of each module. By careful and detailed probing, the effect of various module design features on pollutant formation can be assessed. The techniques presently developed seem adequate to obtain the desired information

Measures for improving the zeppelin airships for long distance transportation

Factors to be considered in the construction of dirigibles include the design and weight of support structures, static and aerodynamic loads on the main ring, the annealing of support materials, and the dynamic gas pressure. Adaptations made for using helium as the lifting gas, and a method for extracting ballast are described

Baryonic Dark Matter

We investigate a simple extension of the Standard Model where the baryon number is a local gauge symmetry and the cold dark matter in the Universe can be described by a fermionic field with baryon number. We refer to this scenario as "Baryonic Dark Matter''. The stability of the dark matter candidate is a natural consequence of the spontaneous breaking of baryon number at the low scale and there is no need to impose an extra discrete symmetry. The constraints from the relic density and the predictions for direct detection are discussed in detail. We briefly discuss the testability of this model using the correlation between the Large Hadron Collider data and possible results from dark matter experiments.Comment: to appear in Physics Letters

Theory for Baryon Number and Dark Matter at the LHC

We investigate the possibility to test the simplest theory for spontaneous baryon number violation at the Large Hadron Collider. In this context the baryon number is a local gauge symmetry spontaneously broken at the low scale through the Brout-Englert-Higgs mechanism. This theory predicts the existence of a leptophobic neutral gauge boson and a fermionic dark matter candidate with baryon number. We study the gauge boson and Higgs decays, and explore the connection between collider signatures and constraints coming from dark matter experiments. We point out an upper bound on the symmetry breaking scale using the relic density constraints which tells us that this model can be tested or ruled out at current or future collider experiments.Comment: 30 pages, 9 figures, typos corrected, new appendix, version to appear in PR

Consistency test of neutrinoless double beta decay with one isotope

We discuss a consistency test which makes it possible to discriminate unknown nuclear background lines from neutrinoless double beta decay with only one isotope. By considering both the transition to the ground state and to the first excited $0^+$ state, a sufficiently large detector can reveal if neutrinoless double beta decay or some other nuclear physics process is at work. Such a detector could therefore simultaneously provide a consistency test for a certain range of Majorana masses and be sensitive to lower values of the effective Majorana mass.Comment: 1+12 pages, 4 figures; v2: discussion enhanced, figures improved, matches journal versio

Protecting the Axion with Local Baryon Number

The Peccei-Quinn (PQ) solution to the Strong CP Problem is expected to fail unless the global symmetry U(1)${}_{\rm PQ}$ is protected from Planck-scale operators up to high mass dimension. Suitable protection can be achieved if the PQ symmetry is an automatic consequence of some gauge symmetry. We highlight that if baryon number is promoted to a gauge symmetry, the exotic fermions needed for anomaly cancellation can elegantly provide an implementation of the Kim-Shifman-Vainshtein-Zakharov 'hidden axion' mechanism with a PQ symmetry protected from Planck-scale physics.Comment: 5 pages; v2: models improved, references adde