1,355 research outputs found
Annoyance from transportation noise: relationships with exposure metrics DNL and DENL and their confidence intervals.
We present a model of the distribution of noise annoyance with the mean varying as a function of the noise exposure. Day-night level (DNL) and day-evening-night level (DENL) were used as noise descriptors. Because the entire annoyance distribution has been modeled, any annoyance measure that summarizes this distribution can be calculated from the model. We fitted the model to data from noise annoyance studies for aircraft, road traffic, and railways separately. Polynomial approximations of relationships implied by the model for the combinations of the following exposure and annoyance measures are presented: DNL or DENL, and percentage "highly annoyed" (cutoff at 72 on a scale of 0-100), percentage "annoyed" (cutoff at 50 on a scale of 0-100), or percentage (at least) "a little annoyed" (cutoff at 28 on a scale of 0-100). These approximations are very good, and they are easier to use for practical calculations than the model itself, because the model involves a normal distribution. Our results are based on the same data set that was used earlier to establish relationships between DNL and percentage highly annoyed. In this paper we provide better estimates of the confidence intervals due to the improved model of the relationship between annoyance and noise exposure. Moreover, relationships using descriptors other than DNL and percentage highly annoyed, which are presented here, have not been established earlier on the basis of a large dataset
Gravitational Waves in Bianchi Type-I Universes I: The Classical Theory
The propagation of classical gravitational waves in Bianchi Type-I universes
is studied. We find that gravitational waves in Bianchi Type-I universes are
not equivalent to two minimally coupled massless scalar fields as it is for the
Robertson-Walker universe. Due to its tensorial nature, the gravitational wave
is much more sensitive to the anisotropy of the spacetime than the scalar field
is and it gains an effective mass term. Moreover, we find a coupling between
the two polarization states of the gravitational wave which is also not present
in the Robertson-Walker universe.Comment: 34 papers, written in ReVTeX, submitted to Physical Review
Unexpected Magnetism of Small Silver Clusters
The ground-state electronic, structural, and magnetic properties of small
silver clusters, Ag (2n22), have been studied using a linear
combination of atomic Gaussian-type orbitals within the density functional
theory. The results show that the silver atoms, which are diamagnetic in bulk
environment, can be magnetic when they are grouped together in clusters. The
Ag cluster with icosahedral symmetry has the highest magnetic moment per
atom among the studied silver clusters. The cluster symmetry and the reduced
coordination number specific of small clusters reveal as a fundamental factor
for the onset of the magnetism.Comment: 4 pages, 4 figure
Moulding the teacher: factors shaping teacher enactment of comprehensive sexuality education policy in Ethiopia
Individual and organisational determinants of use of ergonomic devices in healthcare
(CS/IPC): 0.4%/2.7%, day 4 (2.1%/6.1%), day 7 (2.5%/7.9%), day 14 (4.7%/7.3%), and day 90 (1.0%/3.3%) from baseline (preoperative situation). On days 1, 4, and 7 there was a significant difference in leg circumference between the two treatment groups. Conclusions: Edema following femoropopliteal bypass surgery occurs in all patients. For the prevention and treatment of that edema the use of a class I CS proved superior to treatment with IPC. The use of CS remains the recommended practice following femoropopliteal bypass surgery
Environmental and Energy Performance of the Biomass to Synthetic Natural Gas Supply Chain
A quarter of the total primary energy demand in the European Union is met by natural gas. Synthetic natural gas produced through biomass gasification can contribute to a more sustainable energy supply system. A chain analysis of the energetic performance of synthetic natural gas where the upstream, midstream and downstream part are included has not been found in literature. The energy performance of the possible large-scale application of synthetic natural gas is therefore unsure. A model was designed to analyse the performance of the biomass to synthetic natural gas chain and to estimate the effect of 1% synthetic natural gas in the energy system. A break-even distance is introduced to determine whether it is energetically feasible to apply pretreatment. Results show that torrefaction and pelleting are energetically unfeasible within the European Union. Emissions can be reduced with almost 70% compared to a fossil reference scenario. Over 1.2 Mha is required to fulfil 0.25% of the total primary energy demand in the European Union
Moulding the teacher: factors shaping teacher enactment of comprehensive sexuality education policy in Ethiopia
Replicating Nanostructures on Silicon by Low Energy Ion Beams
We report on a nanoscale patterning method on Si substrates using
self-assembled metal islands and low-energy ion-beam irradiation. The Si
nanostructures produced on the Si substrate have a one-to-one correspondence
with the self-assembled metal (Ag, Au, Pt) nanoislands initially grown on the
substrate. The surface morphology and the structure of the irradiated surface
were studied by high-resolution transmission electron microscopy (HRTEM). TEM
images of ion-beam irradiated samples show the formation of sawtooth-like
structures on Si. Removing metal islands and the ion-beam induced amorphous Si
by etching, we obtain a crystalline nanostructure of Si. The smallest
structures emit red light when exposed to a UV light. The size of the
nanostructures on Si is governed by the size of the self-assembled metal
nanoparticles grown on the substrate for this replica nanopatterning. The
method can easily be extended for tuning the size of the Si nanostructures by
the proper choice of the metal nanoparticles and the ion energy in
ion-irradiation. It is suggested that off-normal irradiation can also be used
for tuning the size of the nanostructures.Comment: 12 pages, 7 figures, regular paper submitted to Nanotechnolog
Extensive Modeling of a Coaxial Stub Resonator for Online Fingerprinting of Fluids
A straightforward method of extensive modeling of a lossy stub resonator system for online fingerprinting of fluids is presented in this paper. The proposed model solves the telegrapher's equations including the skin effect and dielectric losses and describes the amplitude versus frequency response of lossy coaxial stub resonators with a fluid under investigation as dielectric. The adequacy of the method is demonstrated by comparing simulations with experimentally obtained data. Even though we applied the model to a coaxial stub resonator for the online fingerprinting of fluids (e.g., for water quality monitoring), the potential applicability of the method reaches further. Indeed, the method introduced here may be useful for different types of sensors based on lossy transmission line theor
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