12,215 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
Validity and Reliability of the Lesbian, Gay, Bisexual Working Alliance Self-Efficacy Scales
In this paper, the authors report on the development and initial psychometric evaluation of the Lesbian, Gay, and Bisexual Working Alliance Self-Efficacy Scales (LGB-WASES) with data collected from two studies and 534 counseling trainees. Exploratory factor analysis results yielded a 32-item scale with a three-factor model (a) Emotional Bond, (b) Establishing Tasks, and (c) Setting Goals. LGB-WASES scores were internally consistent and remained stable over a 3-week period. Construct validity evidence suggests the LGB-WASES scores were (a) positively related to general perceptions of counseling self-efficacy and multicultural counseling competency, (b) negatively related to attitudes toward lesbians and gay men, and (d) unrelated to social desirability. Recommendations for future research are also discussed
A CS J = 2 1 survey of the galactic center region
A CS map of the galactic center region is presented consisting of 15,000 spectra covering -1 deg. less than 3. deg. 6 min., -0 deg.4 min. less than b less than 0 deg. 4 min., each having an rms noise of 0.15 K in 1 MHz filters. CS is a high-excitation molecule, meaning that it is excited into emission only when the ambient density is less than n much greater than or approx. 2 x 10 to the 4th power/cu cm CS emission in the inner 2 deg. of the galaxy is nearly as pervasive as CO emission, in stark contrast to the outer galaxy where CS emission is confined to cloud cores. Galactic center clouds are on average much more dense than outer Galaxy clouds. This can be understood as a necessary consequence of the strong tidal stresses in the inner galaxy
Gated rotation mechanism of site-specific recombination by ϕC31 integrase
Integrases, such as that of the Streptomyces temperate bacteriophage ϕC31, promote site-specific recombination between DNA sequences in the bacteriophage and bacterial genomes to integrate or excise the phage DNA. ϕC31 integrase belongs to the serine recombinase family, a large group of structurally related enzymes with diverse biological functions. It has been proposed that serine integrases use a “subunit rotation” mechanism to exchange DNA strands after double-strand DNA cleavage at the two recombining att sites, and that many rounds of subunit rotation can occur before the strands are religated. We have analyzed the mechanism of ϕC31 integrase-mediated recombination in a topologically constrained experimental system using hybrid “phes” recombination sites, each of which comprises a ϕC31 att site positioned adjacent to a regulatory sequence recognized by Tn3 resolvase. The topologies of reaction products from circular substrates containing two phes sites support a right-handed subunit rotation mechanism for catalysis of both integrative and excisive recombination. Strand exchange usually terminates after a single round of 180° rotation. However, multiple processive “360° rotation” rounds of strand exchange can be observed, if the recombining sites have nonidentical base pairs at their centers. We propose that a regulatory “gating” mechanism normally blocks multiple rounds of strand exchange and triggers product release after a single round
Full-scale ground proximity investigation of a VTOL fighter model aircraft
Exhaust gas ingestion characteristics and induced aerodynamics for vertical takeoff lift engine fighter model in ground proximit
Construction and Measurements of an Improved Vacuum-Swing-Adsorption Radon-Mitigation System
In order to reduce backgrounds from radon-daughter plate-out onto detector
surfaces, an ultra-low-radon cleanroom is being commissioned at the South
Dakota School of Mines and Technology. An improved vacuum-swing-adsorption
radon mitigation system and cleanroom build upon a previous design implemented
at Syracuse University that achieved radon levels of
0.2Bqm. This improved system will employ a better pump and
larger carbon beds feeding a redesigned cleanroom with an internal HVAC unit
and aged water for humidification. With the rebuilt (original) radon mitigation
system, the new low-radon cleanroom has already achieved a 300
reduction from an input activity of Bqm to a
cleanroom activity of Bqm.Comment: 5 pages, 4 figures, Proceedings of Low Radioactivity Techniques (LRT)
2015, Seattle, WA, March 18-20, 201
Lower Limits on Aperture Size for an ExoEarth-Detecting Coronagraphic Mission
The yield of Earth-like planets will likely be a primary science metric for
future space-based missions that will drive telescope aperture size. Maximizing
the exoEarth candidate yield is therefore critical to minimizing the required
aperture. Here we describe a method for exoEarth candidate yield maximization
that simultaneously optimizes, for the first time, the targets chosen for
observation, the number of visits to each target, the delay time between
visits, and the exposure time of every observation. This code calculates both
the detection time and multi-wavelength spectral characterization time required
for planets. We also refine the astrophysical assumptions used as inputs to
these calculations, relying on published estimates of planetary occurrence
rates as well as theoretical and observational constraints on terrestrial
planet sizes and classical habitable zones. Given these astrophysical
assumptions, optimistic telescope and instrument assumptions, and our new
completeness code that produces the highest yields to date, we suggest lower
limits on the aperture size required to detect and characterize a
statistically-motivated sample of exoEarths.Comment: Accepted for publication in ApJ; 38 pages, 16 Figures, 3 Table
Detection of HI 21 cm-line absorption in the Warm Neutral Medium and in the Outer Arm of the Galaxy
Using the Westerbork Synthesis Radio Telescope, we have detected HI 21
cm-line absorption in the Warm Neutral Medium of the Galaxy toward the
extragalactic source 3C147. This absorption, at an LSR velocity of -29+/-4 km/s
with a full width at half maximum of 53+/-6 km/s, is associated with the
Perseus Arm of the Galaxy. The observed optical depth is (1.9+/-0.2)*10**(-3).
The estimated spin temperature of the gas is 3600+/-360 K. The volume density
is 0.4 per cc assuming pressure equilibrium. Toward two other sources, 3C273
and 3C295, no wide HI 21 cm-line absorption was detected. The highest of the
3sigma lower limits on the spin temperature of the Warm Neutral Medium is 2600
K. In addition, we have also detected HI 21 cm-line absorption from high
velocity clouds in the Outer Arm toward 3C147 and 3C380 at LSR velocities of
-117.3, -124.5 and -113.7 km/s respectively. We find two distinct temperature
components in the high velocity clouds with spin temperatures of greater than
1000 K and less than 200 K, respectively.Comment: 21 pages inclusive of 7 figures and 2 table
Impact of aging on the evolution of cooperation in the spatial prisoner's dilemma game
Aging is always present, tailoring our interactions with others and
postulating a finite lifespan during which we are able to exercise them. We
consider the prisoner's dilemma game on a square lattice, and examine how
quenched age distributions and different aging protocols influence the
evolution of cooperation when taking the life experience and knowledge
accumulation into account as time passes. In agreement with previous studies,
we find that a quenched assignment of age to players, introducing heterogeneity
to the game, substantially promotes cooperative behavior. Introduction of aging
and subsequent death as a coevolutionary process may act detrimental on
cooperation but enhances it efficiently if the offspring of individuals that
have successfully passed their strategy is considered newborn. We study
resulting age distributions of players, and show that the heterogeneity is
vital yet insufficient for explaining the observed differences in cooperator
abundance on the spatial grid. The unexpected increment of cooperation levels
can be explained by a dynamical effect that has a highly selective impact on
the propagation of cooperator and defector states.Comment: 7 two-column pages, 5 figures; accepted for publication in Physical
Review
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