Naresuan University Journal
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Sensorless Speed Estimation in Wound Rotor Induction Machines by Spectral Search of the Stator Phase Power Signal
No full textThis paper investigates the feasibility of utilising the stator phase power signal to establish sensorless speed estimation schemes in wound rotor induction machines (WRIMs). To this end the authors derive and validate closed form expressions defining the possible power signal spectral content containing rotor speed information. Based on these, two novel sensorless speed estimation techniques are proposed: the first enables supply frequency independent speed estimation in WRIM extended slip applications, while the second facilitates estimation in a wide operating speed range for scalar controlled WRIM applications based on a sliding-window search of the power spectrum. The proposed techniques are underpinned by a dichotomous search enabled spectral processing algorithm and shown to deliver an increase in attainable real-time estimation rate without compromising estimation accuracy. The performance of reported schemes is assessed and validated in real-time laboratory experiments
Representing the Periphery: Highland Commissioners in the Seventeenth-Century Scottish Parliament, c.1612-1702
No full textWhile a significant amount of work has recently been conducted on the procedure and practices of the pre-1707 Scottish Parliament, remarkably little is known about the nature of local representation within the chamber. This article seeks partially to address that gap through detailed analysis the elected representation of one region – the Scottish Highlands – within the seventeenth-century Parliament. Considering attendance rates, the identity of Highland representatives (‘commissioners’), the means of their election, and their activities once elected, the article argues that Highland engagement with Parliament was much more significant than is often assumed. This, in turn, suggests that further constituency-level studies are needed in order to provide a fuller picture of Parliament’s relationship with the country at large
Finite element analysis of effect of inter-yarn friction on ballistic impact response of woven fabrics
No full textFriction has shown to have a significant effect in determining the ballistic impact performance of woven fabrics. Many efforts were made to investigate how inter-yarn friction affects ballistic impact response of woven fabrics in the past decades. However, fundamental understanding of mechanics mechanisms of how inter-yarn friction works in woven fabric panels still needs to be established and improved. It is vitally important to understand for example how friction affects the distribution of stress and the magnitude of stress in yarns. This is necessary in determining the failure of the yarns and the energy absorption in a ballistic event. This paper presents a detailed analysis on ballistic impact behaviour of woven fabrics using the finite element method. It has been found that the magnitude of stresses on the yarn surface is sensitive to the frictional coefficient between the crossing yarns in the fabric. Increasing friction between the yarns reduces the stress at the edge of the projectile–fabric contact region. The fabric with higher inter-yarn friction between the yarns causes the impacting projectile longer time to penetrate the fabric compared to fabrics with lower friction between the yarns. The energy absorbed by the woven fabrics with higher inter-yarn friction is more than that by fabrics with lower inter-yarn friction. Increasing friction between the yarns decreases the longitudinal wave velocity whereas the transverse wave velocity is increased along with the increase of inter-yarn friction
The impact of fuel properties on the emissions from the combustion of biomass and other solid fuels in a fixed bed domestic stove
No full textExperimental results are presented on the emissions froma single combustion chamber stove burningwood, coal and processed fuels. This technique was used to permit comparisons to bemade of the influence of different fuel types without it being influenced by the effects of secondary combustion.Measurements were made of CO, NOx and fine particulates during themajor phases of combustion, namely flaming and smouldering.Measurements of the particulates were made in two ways: firstly using a gravimetric total particulate measurement and secondly using a cyclone technique to give PM2.5 and PM10 size fractions. Smoke emissions from the different fuels were very dependent on the phase of combustion especially for the total particulate results,where flaming phase emissionsweremuch higher than in the smouldering phase. Itwas found that the particulate emission factors for the wood fuelswere dependent on the volatile contentwhilst the coals followed a different pattern. NOx was linearly dependent on the fuel-N content for all the fuel types, but the relationship for biomass is different from that for coal. CO emissions were very dependent on the combustion phase
Implementation of Non-Intrusive Jet Exhaust Species Distribution Measurements Within a Test Facility
No full textWe report on the installation and commissioning of two systems for the measurement of cross-sectional distributions of pollutant species in jet exhaust, within the engine ground test facility at INTA, Madrid. These systems use optical tomography techniques to estimate the cross-sectional distributions of CO2 and soot immediately behind the engine. The systems are designed to accommodate the largest civil aviation engines currently in service, without obstruction of the exhaust or bypass flows and with negligible effect upon the entrained flow behavior. We describe the physical construction and installation status of each system. In the case of the CO2 system, we examine the challenges of achieving the structural rigidity necessary for adequate suppression of pointing error within 126 laser-based transmittance measurements, each utilizing a 7 m overall path length. We describe methods developed for efficient implementation of co-planarity and 4-degree-of-freedom alignment of individual paths within this beam array. We also present laboratory performance data for three alternative optical designs that differ in their approach to the management of pointing error and turbulence-induced beam wander and spread. The FLITES soot monitoring capability is based on laser induced incandescence (LII) and uses a short-pulse fiber laser and two CCD cameras, in an autoprojection arrangement. We describe the measurement geometry currently being implemented in the test cell and discuss optical design issues, including once again the effect of the plume itself
Planck 2015 results:XIII. Cosmological parameters
No full textThis paper presents cosmological results based on full-mission Planck observations of temperature and polarization anisotropies of the cosmic microwave background (CMB) radiation. Our results are in very good agreement with the 2013 analysis of the Planck nominal-mission temperature data, but with increased precision. The temperature and polarization power spectra are consistent with the standard spatially-flat 6-parameter ΛCDM cosmology with a power-law spectrum of adiabatic scalar perturbations (denoted "base ΛCDM" in this paper). From the Planck temperature data combined with Planck lensing, for this cosmology we find a Hubble constant, H0 = (67.8 ± 0.9) km s-1Mpc-1, a matter density parameter Ωm = 0.308 ± 0.012, and a tilted scalar spectral index with ns = 0.968 ± 0.006, consistent with the 2013 analysis. Note that in this abstract we quote 68% confidence limits on measured parameters and 95% upper limits on other parameters. We present the first results of polarization measurements with the Low Frequency Instrument at large angular scales. Combined with the Planck temperature and lensing data, these measurements give a reionization optical depth of τ = 0.066 ± 0.016, corresponding to a reionization redshift of \hbox{}. These results are consistent with those from WMAP polarization measurements cleaned for dust emission using 353-GHz polarization maps from the High Frequency Instrument. We find no evidence for any departure from base ΛCDM in the neutrino sector of the theory; for example, combining Planck observations with other astrophysical data we find Neff = 3.15 ± 0.23 for the effective number of relativistic degrees of freedom, consistent with the value Neff = 3.046 of the Standard Model of particle physics. The sum of neutrino masses is constrained to â'mν < 0.23 eV. The spatial curvature of our Universe is found to be very close to zero, with | ΩK | < 0.005. Adding a tensor component as a single-parameter extension to base ΛCDM we find an upper limit on the tensor-to-scalar ratio of r0.002< 0.11, consistent with the Planck 2013 results and consistent with the B-mode polarization constraints from a joint analysis of BICEP2, Keck Array, and Planck (BKP) data. Adding the BKP B-mode data to our analysis leads to a tighter constraint of r0.002 < 0.09 and disfavours inflationarymodels with a V(φ) φ2 potential. The addition of Planck polarization data leads to strong constraints on deviations from a purely adiabatic spectrum of fluctuations. We find no evidence for any contribution from isocurvature perturbations or from cosmic defects. Combining Planck data with other astrophysical data, including Type Ia supernovae, the equation of state of dark energy is constrained to w =-1.006 ± 0.045, consistent with the expected value for a cosmological constant. The standard big bang nucleosynthesis predictions for the helium and deuterium abundances for the best-fit Planck base ΛCDM cosmology are in excellent agreement with observations. We also constraints on annihilating dark matter and on possible deviations from the standard recombination history. In neither case do we find no evidence for new physics. The Planck results for base ΛCDM are in good agreement with baryon acoustic oscillation data and with the JLA sample of Type Ia supernovae. However, as in the 2013 analysis, the amplitude of the fluctuation spectrum is found to be higher than inferred from some analyses of rich cluster counts and weak gravitational lensing. We show that these tensions cannot easily be resolved with simple modifications of the base ΛCDM cosmology. Apart from these tensions, the base ΛCDM cosmology provides an excellent description of the Planck CMB observations and many other astrophysical data sets.</p
Covalency hinders AnO2(H2O)+ --> AnO(OH)2+ isomerisation (An = Pa-Pu)
No full textThe enthalpies of the reactions AnO2 +  AnO+ + O and AnO2 + + H2O  AnO2(H2O)+, and those of the isomerisation of the latter to AnO(OH)2 +, have been calculated for An = Pa–Pu. The data match previous experimental and computational values very closely, and the computed enthalpy for the isomerisation of PaO2(H2O)+ to PaO(OH)2 +, requested by the authors of Inorg. Chem. 2015, 54, 7474, is found to be 0.8 kJ/mol. The NPA, NBO and QTAIM approaches are used to probe covalency in the An–Oyl bond of AnO2(H2O)+, and all metrics agree that these bonds become increasingly covalent as the 5f series is crossed, providing rationalisation for the increasingly endothermic isomerisation reactions. QTAIM analysis indicates that the An=O and An–OH bonds in the oxide hydroxide isomers also become increasingly covalent as the 5f series is crossed
