11,364 research outputs found
Steam storage systems for flexible biomass CHP plants - Evaluation and initial model based calculation
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Within the present study a novel concept for the demand-oriented power generation of a solid-biomass fueled combined heat and power (CHP) plant is investigated. The integration of a steam storage system into the plants process enables a decoupling of the steam (boiler) and the power generation (steam turbine). By buffering the steam, the power output of the turbine can be adjusted without changing the rated thermal capacity of the plant. Various available storage systems are selected and comparatively evaluated applying the adapted analytic hierarchy process (AHP). The technology assessment revealed that the combination of a steam accumulator and solid concrete storage represents the best suiting option. An initial model based simulation study is performed to identify the fundamental behaviour of this system, integrated in a biomass CHP plant. The operation principle is has proved their technical feasibility and seems to be applicable at a commercial scale. According to the modelling results flexible short term power generation in a time range of up to fifteen minutes is applicable. A load-range of almost the plants rated capacity can be achieved
Tridactyl tracks from the Lavini di Marco dinosaur ichnosite (Hettangian, Southern Alps, NE Italy). Ichnotaxonomical review and palaeobiogeography
The use of aerial- and close-range photogrammetry for the mapping of the Lavini di Marco tracksite (Hettangian, Southern Alps, NE Italy)
(EXCERPT FROM ABSTRACT) Close-range photogrammetry was executed following the procedure proposed by Mallison & Wings (2014). More than seventy 3D models were obtained and interpreted by means of color-coded and contour line images, which allow to improve the ichno- logical knowledge of the tracksite. The 3D models of the best-preserved tracks were used for the osteological reconstruction of the trackmakers’ autopodia, supposing the arthral position of the phalangeal pads. Three indirect methods were used to correlate tracks and their trackmakers: (i) synapomorphy-based approach; (ii) phenetic correlation; (iii) coincidence correlation (see Carrano & Wilson, 2001)
The final map was produced with different level of knowledge due to the distribution of tracks and current state of site preservation. Furthermore, it represents a complete documentation that will be used for future work of enhancement, preservation and valorization of the tracksite.
The ichnotaxonomical review of the quadrupedal trackways led us to emend the diagnosis of Lavinipes cheminii Avanzini et al. (2003) and to assign several other sparse tracks and trackways to L. chemini. The skeletal reconstruction of fore and hind limbs points towards Gongxianosaurus sp. as the most suitable trackmaker of L. cheminii. The herein supposed Laurasian affinity of the Lavini di Marco dinosaur assemblage clashes with the previous hypotheses that always link the Southern Alps sector with the Gondwana mainland
Room temperature GW bar detector with opto-mechanical readout
We present the full implementation of a room-temperature gravitational wave
bar detector equipped with an opto-mechanical readout. The mechanical
vibrations are read by a Fabry--Perot interferometer whose length changes are
compared with a stable reference optical cavity by means of a resonant laser.
The detector performance is completely characterized in terms of spectral
sensitivity and statistical properties of the fluctuations in the system output
signal. The new kind of readout technique allows for wide-band detection
sensitivity and we can accurately test the model of the coupled oscillators for
thermal noise. Our results are very promising in view of cryogenic operation
and represent an important step towards significant improvements in the
performance of massive gravitational wave detectors.Comment: 7 figures, submitted to Phys. Rev.
Finding a reflexive voice : -- researching the problems of implementing new learning practices within a New Zealand manufacturing organisation : a 100pt thesis presented in partial fulfilment of the requirements for the degree of Master of Management in Human Resources Management at Massey University
This study explored the social forces mediating manager's participation in a new reflexive participative learning practice designed to improve profitability within a New Zealand manufacturing organisation. Despite a large theoretical and managerial body of literature on organisational learning there has been little empirical investigation of how people experience and engage their reflexivity towards challenging the status-quo to create high level learning and new knowledge. Power was identified as a potential moderator of the reflexive learning experience and the variable relations of power and learning were constructed from a review of literature and these relationships were explored and investigated within the case study. Two prevailing discourses were identified as powerful moderators of public reflexivity, the traditionalist discourse which constructed managers actions and conversations towards insularism and survivalist concerns and the productionist discourse in which institutionalised production practices encircled and mediated managers actions and what constituted legitimacy in conversations. This study used a critical action research method to place the reflexive experience of managers and the researcher at the centre of the study and provide data representative of the social discourses that constructed variable freedoms and constraints upon the reflexive voice
Experimental measurement of photothermal effect in Fabry-Perot cavities
We report the experimental observation of the photothermal effect. The
measurements are performed by modulating the laser power absorbed by the
mirrors of two high-finesse Fabry-Perot cavities. The results are very well
described by a recently proposed theoretical model [M. Cerdonio, L. Conti, A.
Heidmann and M. Pinard, Phys. Rev. D 63 (2001) 082003], confirming the
correctness of such calculations. Our observations and quantitative
characterization of the photothermal effect demonstrate its critical importance
for high sensitivity interferometric displacement measurements, as those
necessary for gravitational wave detection.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
H-Band Spectroscopic Classification of OB Stars
We present a new spectroscopic classification for OB stars based on H-band
(1.5 micron to 1.8 micron) observations of a sample of stars with optical
spectral types. Our initial sample of nine stars demonstrates that the
combination of He I 1.7002 micron and H Brackett series absorption can be used
to determine spectral types for stars between about O4 and B7 (to within about
+/- 2 sub-types). We find that the Brackett series exhibits luminosity effects
similar to the Balmer series for the B stars. This classification scheme will
be useful in studies of optically obscured high mass star forming regions. In
addition, we present spectra for the OB stars near 1.1 micron and 1.3 micron
which may be of use in analyzing their atmospheres and winds.Comment: Accepted by AJ, 16 pages Latex (aastex4.0) including 4 figures and 2
tables. A complete PostScript copy is available at
ftp://degobah.colorado.edu/pub/rblum/Hband
Multi-objective optimization of nitinol stent design
Nitinol stents continuously experience loadings due to pulsatile pressure, thus a given stent design should possess an adequate fatigue strength and, at the same time, it should guarantee a sufficient vessel scaffolding. The present study proposes an optimization framework aiming at increasing the fatigue life reducing the maximum strut strain along the structure through a local modification of the strut profile.The adopted computational framework relies on nonlinear structural finite element analysis combined with a Multi Objective Genetic Algorithm, based on Kriging response surfaces. In particular, such an approach is used to investigate the design optimization of planar stent cell.The results of the strut profile optimization confirm the key role of a tapered strut design to enhance the stent fatigue strength, suggesting that it is possible to achieve a marked improvement of both the fatigue safety factor and the scaffolding capability simultaneously. The present study underlines the value of advanced engineering tools to optimize the design of medical devices
Thermal and back-action noises in dual-sphere gravitational-waves detectors
We study the sensitivity limits of a broadband gravitational-waves detector
based on dual resonators such as nested spheres. We determine both the thermal
and back-action noises when the resonators displacements are read-out with an
optomechanical sensor. We analyze the contributions of all mechanical modes,
using a new method to deal with the force-displacement transfer functions in
the intermediate frequency domain between the two gravitational-waves sensitive
modes associated with each resonator. This method gives an accurate estimate of
the mechanical response, together with an evaluation of the estimate error. We
show that very high sensitivities can be reached on a wide frequency band for
realistic parameters in the case of a dual-sphere detector.Comment: 10 pages, 7 figure
Damping of long-wavelength collective excitations in quasi-onedimensional Fermi liquids
The imaginary part of the exchange-correlation kernel in the longitudinal
current-current response function of a quasi-onedimensional Fermi liquid is
evaluated by an approximate decoupling in the equation of motion for the
current density, which accounts for processes of excitation of two
particle-hole pairs. The two-pair spectrum determines the intrinsic damping
rate of long-wavelength collective density fluctuations, which is calculated
and contrasted with a result previously obtained for a clean Luttinger liquid.Comment: 9 pages, no figures, Physica B in pres
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