1,711 research outputs found
A methodology and toolkit for the assessment and selection of LZC technologies in the building design process
The advent of environmentally driven building regulations, rising energy costs, and heightened client awareness of energy-related issues has increased the demand for the assessment of building integrated low-carbon (LZC) energy supply systems. However, it is seldom the case that any one software tool fulfils the needs for an appraisal of these types of systems. Therefore, there is a clear need for an effective methodology for the use of a range of software tools in LZC technology analysis. This paper describes a practitioner-driven project within which such a methodology and supporting software (termed a 'toolkit') has been developed. The application of this toolkit to a real design problem is described and the results from the analysis are discussed. The paper also addresses the means by which the results from the analysis can be presented to clients and other stakeholders in the design process
Sigmoid Neural Transfer Function Realised by Percolation
An experiment using the phenomenon of percolation has been conducted to demonstrate the implementation of neural functionality (summing and sigmoid transfer). A simple analog approximation to digital percolation is implemented. The device consists of a piece of amorphous silicon with stochastic bit-stream optical inputs, in which a current percolating from one end to the other defines the neuron output, also in the form of a stochastic bit stream. Preliminary experimental results are presented
Enhancing pasture stability and profitability for producers in Poplar Box and Silver-leaved Ironbark woodlands.
Over 7 years, this project collected data about the pasture, tree and soil surface dynamics of two major Aristida/Bothriochloa pasture types within the eucalypt woodlands of central Queensland. Six different grazing management scenarios were compared ecologically and economically, along with the effects of spring burns and tree killing.
Heavy stocking (3-4 ha per adult equivalent) produced the greatest short-term financial return from healthy pastures but was not a sustainable practice and long-term cash returns were no better than those from moderate stocking. The environmental benefits of moderate grazing over heavy grazing were very clear. Light stocking produced better environmental outcomes compared to moderate stocking but was clearly inferior with respect to economic returns. Killing silver-leaved ironbark trees near Rubyvale produced no measurable improvement in pasture growth or quality for at least 6 years whereas at Injune the same treatment of poplar box trees resulted in an immediate and large enhancement in pasture production and carrying capacity. The gritty red duplex soil at Rubyvale was much more erodible than the grey solodic at Injune although the latter becomes very erodible if the stable surface soil is breached.
Good seasonal rainfall produced faster changes in pasture composition than extremes of grazing management. The perennial grasses were easier to recruit than to eliminate by grazing management changes
Model Building with Gauge-Yukawa Unification
In supersymmetric theories with extra dimensions, the Higgs and matter fields
can be part of the gauge multiplet, so that the Yukawa interactions can arise
from the gauge interactions. This leads to the possibility of gauge-Yukawa
coupling unification, g_i=y_f, in the effective four dimensional theory after
the initial gauge symmetry and the supersymmetry are broken upon orbifold
compactification. We consider gauge-Yukawa unified models based on a variety of
four dimensional symmetries, including SO(10), SU(5), Pati-Salam symmetry,
trinification, and the Standard Model. Only in the case of Pati-Salam and the
Standard Model symmetry, we do obtain gauge-Yukawa unification. Partial
gauge-Yukawa unification is also briefly discussed.Comment: 23 page
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Collisional and Radiative Effects in Transient sub-Doppler Hole Burning: Double Resonance Measurements in CN
We report transient hole-burning and saturation recovery measurements in the CN radical with MHz frequency resolution and 20 ns time resolution. Narrow velocity groups of individual hyperfine levels of selected rotational states in CN (X{sup 2} {Sigma}{sup +}) are depleted and excited (A{sup 2}{pi}{sub i}) with a saturation laser and probed by a counterpropagating, frequency modulated probe beam. Recent work in our lab has used this method to measure and characterize the hyperfine splittings for a set of rotational, fine structure, and parity components of CN (A{sup 2}{pi}{sub i}, v=1). Extending this work, we report time and frequency dependence of the saturation signals following abrupt switching of the CW saturation beam on and off with an electro-optic amplitude modulator. Recovery of the unsaturated absorption following the turnoff of the saturation beam follows pressure-dependent kinetics, driven by collisions with the undissociated NCCN precursor with a rate coefficient of 2 x 10{sup -9} cm{sup 3} s{sup -1} molec{sup -1}. Similar recovery kinetics are observed for two-level saturation resonances, where the signal observed is a combination of X- and A-state kinetics, as well as for three-level crossover resonances, which can be chosen to probe selectively the holefilling in the X state or the decay of velocity-selected A state radicals. The observed recovery rates are 8-10 times faster than the estimated rotationally inelastic contribution. The observed recovery rates are likely dominated by velocity-changing collisions in both X and A states, occurring with similar rates, despite the large difference in the properties of these electronic states. Transient signal risetimes following the turning on of the saturation pulse are consistent with the expected Rabi frequency. At lower pressures ({approx}50 mTorr) and higher beam power ({approx}200 mW), we can observe multiple Rabi cycles before collisions disrupt the coherent excitation and the transient signal reaches a steady state
Ecosystem Capacity for Microbial Biodegradation of Munitions Compounds and Phenanthrene in Three Coastal Waterways in North Carolina, United States
Munitions compounds (i.e., 2,4,6-trinitrotoluene (TNT), octahy-dro-1,3,5,7-tetranitro-1,3,5,7-tetrazocin (HMX), and hexadydro-1,3,5-trinitro-1,3,5-triazin (RDX), also called energetics) were originally believed to be recalcitrant to microbial biodegradation based on historical groundwater chemical attenuation data and laboratory culture work. More recently, it has been established that natural bacterial assemblages in coastal waters and sediment can rapidly metabolize these organic nitrogen sources and even incorporate their carbon and nitrogen into bacterial biomass. Here, we report on the capacity of natural microbial assemblages in three coastal North Carolina (United States) estuaries to metabolize energetics and phenanthrene (PHE), a proxy for terrestrial aromatic compounds. Microbial assemblages generally had the highest ecosystem capacity (mass of the compound mineralized per average estuarine residence time) for HMX (21-5463 kg) RDX (1.4-5821 kg) PHE (0.29-660 kg) TNT (0.25-451 kg). Increasing antecedent precipitation tended to decrease the ecosystem capacity to mineralize TNT in the Newport River Estuary, and PHE and TNT mineralization were often highest with increasing salinity. There was some evidence from the New River Estuary that increased N-demand (due to a phytoplankton bloom) is associated with increased energetic mineralization rates. Using this type of analysis to determine the ecosystem capacity to metabolize energetics can explain why these compounds are rarely detected in seawater and marine sediment, despite the known presence of unexploded ordnance or recent use in military training exercises. Overall, measuring the ecosystem capacity may help predict the effects of climate change (warming and altered precipitation patterns) and other perturbations on exotic compound fate and transport within ecosystems and provide critical information for managers and decision-makers to develop management strategies based on these changes
Spatial Stability of Incompressible Attachment-Line Flow
Linear stability analysis of incompressible attachment-line flow is presented within the spatial framework. The system of perturbation equations is solved using spectral collocation. This system has been solved in the past using the temporal approach and the current results are shown to be in excellent agreement with neutral temporal calculations. Results amenable to direct comparison with experiments are then presented for the case of zero suction. The global solution method utilized for solving the eigenproblem yields, aside from the well-understood primary mode, the full spectrum of least-damped waves. Of those, a new mode, well separated from the continuous spectrum is singled out and discussed. Further, relaxation of the condition of decaying perturbations in the far-field results in the appearance of sinusoidal modes akin to those found in the classical Orr-Sommerfeld problem. Finally, the continuous spectrum is demonstrated to be amenable to asymptotic analysis. Expressions are derived for the location, in parameter space, of the continuous spectrum, as well as for the limiting cases of practical interest. In the large Reynolds number limit the continuous spectrum is demonstrated to be identical to that of the Orr-Sommerfeld equation
Power, norms and institutional change in the European Union: the protection of the free movement of goods
How do institutions of the European Union change? Using an institutionalist approach, this article highlights the interplay between power, cognitive limits, and the normative order that underpins institutional settings and assesses their impact upon the process of institutional change. Empirical evidence from recent attempts to reinforce the protection of the free movement of goods in the EU suggests that, under conditions of uncertainty, actors with ambiguous preferences assess attempts at institutional change on the basis of the historically defined normative order which holds a given institutional structure together. Hence, path dependent and incremental change occurs even when more ambitious and functionally superior proposals are on offer
Megahertz dynamics in skyrmion systems probed with muon-spin relaxation
We present longitudinal-field muon-spin relaxation (LF ÎŒ SR ) measurements on two systems that stabilize a skyrmion lattice (SkL): Cu 2 OSeO 3 , and Co x Zn y Mn 20 â x â y for ( x , y ) = ( 10 , 10 ) , (8, 9), and (8, 8). We find that the SkL phase of Cu 2 OSeO 3 exhibits emergent dynamic behavior at megahertz frequencies, likely due to collective excitations, allowing the SkL to be identified from the ÎŒ SR response. From measurements following different cooling protocols and calculations of the muon stopping site, we suggest that the metastable SkL is not the majority phase throughout the bulk of this material at the fields and temperatures where it is often observed. The dynamics of bulk Co 8 Zn 9 Mn 3 are well described by â 2 GHz excitations that reduce in frequency near the critical temperature, while in Co 8 Zn 8 Mn 4 we observe similar behavior over a wide range of temperatures, implying that dynamics of this kind persist beyond the SkL phase
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