Fluid sample collector Patent

Design and development of fluid sample collecto

Measurement of sigma_Total in e+e- Annihilations Below 10.56 GeV

Using the CLEO III detector, we measure absolute cross sections for e+e- -> hadrons at seven center-of-mass energies between 6.964 and 10.538 GeV. R, the ratio of hadronic and muon pair production cross sections, is measured at these energies with a r.m.s. error <2% allowing determinations of the strong coupling alpha_s. Using the expected evolution of alpha_s with energy we find alpha_s(M_Z^2)=0.126 +/- 0.005 ^{+0.015}_{-0.011}, and Lambda=0.31^{+0.09+0.29}_{-0.08-0.21}.Comment: Comments: Presented at "The 2007 Europhysics Conference on High Energy Physics," Manchester, England, 19-25 July 2007, to appear in the proceedings. Three pages, 1 figur

Phase Structure of 2-Flavor Quark Matter: Heterogeneous Superconductors

We analyze the free energy of charge and color neutral 2-flavor quark matter within the BCS approximation. We consider both the homogeneous gapless superconducting phase and the heterogeneous mixed phase where normal and BCS superconducting phases coexist. We calculate the surface tension between normal and superconducting phases and use it to compare the free energies of the gapless and mixed phases. Our calculation, which retains only the leading order gradient contribution to the free energy, indicates that the mixed phase is energetically favored over an interesting range of densities of relevance to 2 flavor quark matter in neutron stars.Comment: 11 pages, 4 figures. Major Revisions. Includes a detailed discussion of the kinetic terms of the effective theory, instabilities of the gapless phase and the charge neutral phase diagra

A back to back multilevel converter for driving low inductance brushless AC machines

Traditionally, multilevel converters are utilised in medium voltage applications, allowing the DC-link voltage to exceed the switch maximum blocking voltage. Here, their application to control high- efficiency brushless permanent magnet synchronous machines exhibiting low phase inductance is explored, the relative advantages being shown to include reduced current ripple and improved harmonic spectrum. A cost benefit analysis is included along with experimental results from a prototype 5-level back-to-back converter

State-of-charge and state-of-health prediction of lead-acid batteries for hybrid electric vehicles using non-linear observers

The paper describes the application of state-estimation techniques for the real-time prediction of state-of-charge (SoC) and state-of-health (SoH) of lead-acid cells. Approaches based on the extended Kalman filter (EKF) are presented to provide correction for offset, drift and state divergence - an unfortunate feature of more traditional coulomb-counting techniques. Experimental results are employed to demonstrate the relative attributes of the proposed methodolog

Sensorless control of deep-sea ROVs PMSMs excited by matrix converters

The paper reports the development of model-based sensorless control methodologies for driving PMSMs using matrix converters. In particular, experimental results show that observer-based state-estimation techniques normally employed for sensorless control of PMSMs using voltage source inverters (VSIs), can be readily exported to matrix converter counterparts with minimal additional computational overhead. Furthermore, zero speed start-up and speed reversal are experimentally demonstrated. Finally, the observer is designed to be fault tolerant such that upon detection of a broken terminal (phase fault), the PMSM remains operational and could be utilized to provide a limp-home capabilit

Transmission Oscillator Ultrasonic Spectrometer (TOUS): A new research instrument

TOUS is capable for measuring very small changes in acoustic attenuation and phase velocity. Its high sensitivity to small changes in ultrasonic absorption results in part from operation under marginal conditions. In spite of high sensitivity, TOUS system is relatively simple, inexpensive, and compact

Observer techniques for estimating the state-of-charge and state-of-health of VRLABs for hybrid electric vehicles

The paper describes the application of observer-based state-estimation techniques for the real-time prediction of state-of-charge (SoC) and state-of-health (SoH) of lead-acid cells. Specifically, an approach based on the well-known Kalman filter, is employed, to estimate SoC, and the subsequent use of the EKF to accommodate model non-linearities to predict battery SoH. The underlying dynamic behaviour of each cell is based on a generic Randles' equivalent circuit comprising of two-capacitors (bulk and surface) and three resistors, (terminal, transfer and self-discharging). The presented techniques are shown to correct for offset, drift and long-term state divergence-an unfortunate feature of employing stand-alone models and more traditional coulomb-counting techniques. Measurements using real-time road data are used to compare the performance of conventional integration-based methods for estimating SoC, with those predicted from the presented state estimation schemes. Results show that the proposed methodologies are superior with SoC being estimated to be within 1% of measured. Moreover, by accounting for the nonlinearities present within the dynamic cell model, the application of an EKF is shown to provide verifiable indications of SoH of the cell pack

An experimental and theoretical investigation of particle–wall impacts in a T-junction

Understanding the behaviour of particles entrained in a fluid flow upon changes in flow direction is crucial in problems where particle inertia is important, such as the erosion process in pipe bends.We present results on the impact of particles in a T-shaped channel in the laminar-turbulent transitional regime. The impacting event for a given system is described in terms of the Reynolds number and the particle Stokes number. Experimental results for the impact are compared with the trajectories predicted by theoretical particle tracing models for a range of configurations to determine the role of the viscous boundary layer in retarding the particles and reducing the rate of collision with the substrate. In particular a 2D model based on a stagnation point flow is used together with 3D numerical simulations. We show how the simple 2D model provides a tractable way of understanding the general collision behaviour, while more advanced 3D simulation can be helpful in understanding the details of the flow