923 research outputs found
Recommended from our members
Indoor air quality in California homes with code-required mechanical ventilation.
Data were collected in 70 detached houses built in 2011-2017 in compliance with the mechanical ventilation requirements of California's building energy efficiency standards. Each home was monitored for a 1-week period with windows closed and the central mechanical ventilation system operating. Pollutant measurements included time-resolved fine particulate matter (PM2.5 ) indoors and outdoors and formaldehyde and carbon dioxide (CO2 ) indoors. Time-integrated measurements were made for formaldehyde, NO2 , and nitrogen oxides (NOX ) indoors and outdoors. Operation of the cooktop, range hood, and other exhaust fans was continuously recorded during the monitoring period. Onetime diagnostic measurements included mechanical airflows and envelope and duct system air leakage. All homes met or were very close to meeting the ventilation requirements. On average, the dwelling unit ventilation fan moved 50% more airflow than the minimum requirement. Pollutant concentrations were similar to or lower than those reported in a 2006-2007 study of California new homes built in 2002-2005. Mean and median indoor concentrations were lower by 44% and 38% for formaldehyde and 44% and 54% for PM2.5 . Ventilation fans were operating in only 26% of homes when first visited, and the control switches in many homes did not have informative labels as required by building standards
Benefits of Organic Farming for Society
Recent food scares have lead to a boom in demand for organic products and an increasing awareness of policy makers of the potential benefits of organic farming. However, policies specifically targeting organic farming support do not remain beyond dispute and a sound justification of these is in great demand. The potential specific contribution of organic farming to the achievement of some of the key objectives of the European Common Agricultural Policy, e.g. competitiveness of agriculture, farming income, food supply, food quality and minimisation of negative environmental impacts of agricultural production are discussed.
It is argued that organic farming can contribute to the objectives of the CAP, however, addressing the various objectives to different degrees. The environmental effects of organic farming seem to be largely positive in comparison to conventional farming on a per hectare basis in all categories, be it biodiversity, input-output balances or soil and water resources, although other farming systems might perform better with respect to single indicators or when results are related to the amount of produced output. The quality of organically produced food seems to be higher than that of conventionally produced food for several indicators, for example, the risk of food contamination with pesticides and or nitrate tends to be lower. Income levels from organic farming are on average comparable to income generated on conventional farms, and organic farming is clearly a profitable alternative for quite a few farms in Europe. With respect to rural development organic farming is expected to have little direct effects, e.g. on unemployment rates, although small scale marketing and processing initiatives may contribute directly to rural employment. However, indirect effects such as increased employment in tourism due to a positive “ecological” image of a region can be of importance.
Conclusively, organic farming can contribute to several of the declared policy objectives of the CAP. However, the information available to date does not permit a clear conclusion if organic farming achieves desirable effects at lower costs than other farming systems. Nevertheless, the positive effects on a broad range of objectives clearly justifies the support of organic farming and is therefore recommended
Analyzing technology acceptance and perception of privacy in ambient assisted living for using sensor-based technologies
People increasingly use various technologies that enable them to ease their everyday lives in different areas. Not only wearable devices are gaining ground, but also sensor-based ambient devices and systems are increasingly perceived as beneficial in supporting users. Especially older and/or frail persons can benefit from the so-called lifelogging technologies assisting the users in different activities and supporting their mobility and autonomy. This paper empirically investigates users' technology acceptance and privacy perceptions related to sensor-based applications implemented in private environments (i.e., passive infrared sensors for presence detection, humidity and temperature sensors for ambient monitoring, magnetic sensors for user-furniture interaction). For this purpose, we designed an online survey entitled "Acceptance and privacy perceptions of sensor-based lifelogging technologies"and collected data from N = 312 German adults. In terms of user acceptance, statistical analyses revealed that participants strongly agree on the benefits of such sensorbased ambient technologies, also perceiving these as useful and easy to use. Nevertheless, their intention to use the sensor-based applications was still rather limited. The evaluation of privacy perceptions showed that participants highly value their privacy and hence require a high degree of protection for their personal data. The potential users assessed the collection of data especially in the most intimate spaces of domestic environments, such as bathrooms and bedrooms, as critical. On the other hand, participants were also willing to provide complete data transparency in case of an acute risk to their health. Our results suggest that users' perceptions of personal privacy largely affect the acceptance and successful adoption of sensor-based lifelogging in home environments
Model Order Reduction for Rotating Electrical Machines
The simulation of electric rotating machines is both computationally
expensive and memory intensive. To overcome these costs, model order reduction
techniques can be applied. The focus of this contribution is especially on
machines that contain non-symmetric components. These are usually introduced
during the mass production process and are modeled by small perturbations in
the geometry (e.g., eccentricity) or the material parameters. While model order
reduction for symmetric machines is clear and does not need special treatment,
the non-symmetric setting adds additional challenges. An adaptive strategy
based on proper orthogonal decomposition is developed to overcome these
difficulties. Equipped with an a posteriori error estimator the obtained
solution is certified. Numerical examples are presented to demonstrate the
effectiveness of the proposed method
Indications for the Nonexistence of Three-Neutron Resonances near the Physical Region
The pending question of the existence of three-neutron resonances near the
physical energy region is reconsidered. Finite rank neutron-neutron forces are
used in Faddeev equations, which are analytically continued into the unphysical
energy sheet below the positive real energy axis. The trajectories of the
three-neutron S-matrix poles in the states of total angular momenta and parity
J^\pi=1/2 +- and J^\pi= 3/2 +- are traced out as a function of artificial
enhancement factors of the neutron-neutron forces. The final positions of the
S-matrix poles removing the artificial factors are found in all cases to be far
away from the positive real energy axis, which provides a strong indication for
the nonexistence of nearby three-neutron resonances. The pole trajectories
close to the threshold E=0 are also predicted out of auxiliary generated
three-neutron bound state energies using the Pad\'e method and agree very well
with the directly calculated ones.Comment: 20 pages, 7 Postscript figures, fig.1 is corrected, uses relax.st
Consistent alpha-cluster description of the 12C (0^+_2) resonance
The near-threshold 12C (0^+_2) resonance provides unique possibility for fast
helium burning in stars, as predicted by Hoyle to explain the observed
abundance of elements in the Universe. Properties of this resonance are
calculated within the framework of the alpha-cluster model whose two-body and
three-body effective potentials are tuned to describe the alpha - alpha
scattering data, the energies of the 0^+_1 and 0^+_2 states, and the
0^+_1-state root-mean-square radius. The extremely small width of the 0^+_2
state, the 0_2^+ to 0_1^+ monopole transition matrix element, and transition
radius are found in remarkable agreement with the experimental data. The
0^+_2-state structure is described as a system of three alpha-particles
oscillating between the ground-state-like configuration and the elongated chain
configuration whose probability exceeds 0.9
The f_LT Response Function of D(e,e'p)n at Q^2=0.33(GeV/c)^2
The interference response function f_LT (R_LT) of the D(e,e'p)n reaction has
been determined at squared four-momentum transfer Q^2 = 0.33 (GeV/c)^2 and for
missing momenta up to p_miss= 0.29 (GeV/c). The results have been compared to
calculations that reproduce f_LT quite well but overestimate the cross sections
by 10 - 20% for missing momenta between 0.1 (GeV/c) and 0.2 (GeV/c) .Comment: 12 Pages, 10 figure
- …