11,439 research outputs found
Complex energy simlulation using simplified user interaction mechanisms
Simulation of energy systems and associated thermodynamic domains is very powerful in delivering precise information at high resolution. Modelling software requires detailed information about the energy system. The specialised user usually has questions about specific aspects of the energy system and may not be interested in the complete set of outputs available from simulation results. Similarly the specialised user may only be concerned about a subset of the inputs provided to the software. This suggests an opportunity to develop an input / output scheme tailored for the specialised user. The power of simulation can be accessed through the use of simplified interfaces. Although these restrict flexibility in terms of model input / output data the specialised user is only interested in a subset of the capability of the underlying simulation tool. Robust results rely on a consistent underlying simulation context, this restricted interface ensures that only the parameters of interest to the users are modifiable and that other simulation parameters remain fixed ensuring a consistent and repeatable output. One such example of limited user interaction for both output and input is the ADEPT interface to whole building and plant dynamic modelling and simulation suite ESPÂr (ESRU 2002). The interface was developed in the context of the UK domesticheating market. This paper describes the development of the ADEPT tool and associated spreadsheet templates in order to provide a readily usable platform for the study of domestic heating systems and controls for plant and control components manufacturers, regulatory authorities and research organisations
Cosmological Consequences of String Axions
Axion fluctuations generated during inflation lead to isocurvature and
non-Gaussian temperature fluctuations in the cosmic microwave background
radiation. Following a previous analysis for the model independent string axion
we consider the consequences of a measurement of these fluctuations for two
additional string axions. We do so independent of any cosmological assumptions
except for the axions being massless during inflation. The first axion has been
shown to solve the strong CP problem for most compactifications of the
heterotic string while the second axion, which does not solve the strong CP
problem, obeys a mass formula which is independent of the axion scale. We find
that if gravitational waves interpreted as arising from inflation are observed
by the PLANCK polarimetry experiment with a Hubble constant during inflation of
H_inf \apprge 10^13 GeV the existence of the first axion is ruled out and the
second axion cannot obey the scale independent mass formula. In an appendix we
quantitatively justify the often held assumption that temperature corrections
to the zero temperature QCD axion mass may be ignored for temperatures T
\apprle \Lambda_QCD.Comment: 27 pages, 4 figures; v2: References corrected; v3: Assumptions
simplified, minor corrections, conclusions unchange
High-resolution neutron depolarization microscopy of the ferromagnetic transitions in NiAl and HgCrSe under pressure
We performed neutron imaging of ferromagnetic transitions in NiAl and
HgCrSe crystals. These neutron depolarization measurements revealed
bulk magnetic inhomogeneities in the ferromagnetic transition temperature with
spatial resolution of about 100~m. To obtain such spatial resolution, we
employed a novel neutron microscope equipped with Wolter mirrors as a neutron
image-forming lens and a focusing neutron guide as a neutron condenser lens.
The images of NiAl show that the sample does not homogeneously go through
the ferromagnetic transition; the improved resolution allowed us to identify a
distribution of small grains with slightly off-stoichiometric composition.
Additionally, neutron depolarization imaging experiments on the chrome spinel,
HgCrSe, under pressures up to 15~kbar highlight the advantages of the
new technique especially for small samples or sample environments with
restricted sample space. The improved spatial resolution enables one to observe
domain formation in the sample while decreasing the acquisition time despite
having a bulky pressure cell in the beam
Predicting the conformations of peptides and proteins in early evolution. A review article submitted to Biology Direct
Considering that short, mainly heterochiral, polypeptides with a high glycine content are expected to have played a prominent role in evolution at the earliest stage of life before nucleic acids were available, we review recent knowledge about polypeptide three-dimensional structure to predict the types of conformations they would have adopted. The possible existence of such structures at this time leads to a consideration of their functional significance, and the consequences for the course of evolution
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On-chip micro-evaporation: Experimental evaluation of liquid pumping and vapor compression cooling systems
This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.Thermal designers of data centers and server manufacturers are showing a great concern regarding the cooling of new generation data centers, which are more compact and dissipate more power than is currently
possible to cool by conventional air conditioning systems. With very large data centers exceeding 100 000 servers,
some consume more than 50 MW [1] of electrical energy to operate, energy which is directly converted to heat and then simply wasted as it is dissipated into the atmosphere. A potentially significantly better solution would be to make use of on-chip two-phase cooling [2], which, besides improving the cooling performance at the chip level, also adds the capability to reuse the waste heat in a convenient manner, since higher evaporating and condensing
temperatures of the two-phase cooling system (from 60-95°C) are possible with such a new green cooling technology. In the present project, two such two-phase cooling cycles using micro-evaporation technology were
experimentally evaluated with specific attention being paid to energy consumption, overall exergetic efficiency and controllability. The main difference between the two cooling cycles is the driver, where both a mini-compressor and a gear pump were considered. The former has the advantage due to its appeal of energy recovery since its exergy potential is higher and the waste heat is exported at a higher temperature for reuse.This study is supported by: the Swiss Commission for Technology and Innovation (CTI) contract number 6862.2; the LTCM laboratory; IBM ZĂŒrich Research
Laboratory (Switzerland) and Embraco (Brazil)
Incipient ferroelectricity in 2.3% tensile-strained CaMnO3 films
Epitaxial CaMnO3 films grown with 2.3% tensile strain on (001)-oriented
LaAlO3 substrates are found to be incipiently ferroelectric below 25 K. Optical
second harmonic generation (SHG) was used for the detection of the incipient
polarization. The SHG analysis reveals that CaMnO3 crystallites with in-plane
orientation of the orthorhombic b axis contribute to an electric polarization
oriented along the orthorhombic a (resp.\ c) axis in agreement with the
predictions from density functional calculations
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The other side of critical psychology? A review of the utility of Lacanian psychoanalysis with a focus on the theory of the Four Discourses
Bond Orientational Order, Molecular Motion and Free Energy of High Density DNA Mesophases
By equilibrating condensed DNA arrays against reservoirs of known osmotic
stress and examining them with several structural probes, it has been possible
to achieve a detailed thermodynamic and structural characterization of the
change between two distinct regions on the liquid crystalline phase digram: a
higher-density hexagonally packed region with long-range bond orientational
order in the plane perpendicular to the average molecular direction; and a
lower-density cholesteric region with fluid-like positional order. X-rays
scattering on highly ordered DNA arrays at high density and with the helical
axis oriented parallel to the incoming beam showed a six-fold azimuthal
modulation of the first order diffraction peak that reflects the macroscopic
bond-orientational order. Transition to the less-dense cholesteric phase
through osmotically controlled swelling shows the loss of this bond
orientational order that had been expected from the change in optical
birefringence patterns and that is consistent with a rapid onset of molecular
positional disorder. This change in motion was previously inferred from
intermolecular force measurements and is now confirmed by NMR.
Controlled reversible swelling and compaction under osmotic stress, spanning a
range of densities between mg/ml to mg/ml, allows
measurement of the free energy changes throughout each phase and at the phase
transition, essential information for theories of liquid-crystalline states.Comment: 14 pages, 3 figures in gif format available at
http://abulafia.mgsl.dcrt.nih.gov/pics.html E-mail: [email protected]
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