530 research outputs found
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IMPROVING THE ENERGY PERFORMANCE OF RESIDENTIAL CLOTHESDRYERS
Experiments were conducted to evaluate four techniques to improve the energy efficiency of electrically-heated domestic clothes dryers. Reduced air flow rate and heater input led to energy savings around 8%, while recirculation of a portion of the exhaust air back into the clothes dryer reduced energy consumption by approximately 18%. These two measures are attractive because of their low cost. Two modes of using an air-to-air heat exchanger for heat recovery were considered. The first is to preheat the inlet air with heat from the exhaust air, which resulted in 20 to 26% energy savings. The second mode is 100% recirculation of air through the dryer and a heat exchanger and condensation of water from this air in the heat exchanger by using indoor air. as a heat sink. This resulted in 100% heat recovery (i.e., all heat was rejected to indoors) but the energy consumption of the dryer was increased by up to 6%. To maximize energy savings, a clothes dryer with a heat exchanger can be equipped to operate in the preheating mode in the summer and in the recirculation/condensation mode in the winter. The last measure investigated recirculation, through a heat pump (i.e., dehumidifier), also resulted in a 100% heat recovery and, in addition, up to a 33% reduction in dryer energy consumption, but this technique also yielded long drying times
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Hygroscopic Fine Mode Particle Deposition on Electronic Circuitsand Resulting Degradation of Circuit Performance: An ExperimentalStudy
A portion of electronic equipment failures is a consequenceof particle deposition on electronic circuits in normal indoorenvironments. Deposited hygroscopic particles reduce the electricalisolation (EI) between conductors. In laboratory experiments, weinvestigated the mechanisms, locations, and effects of particledeposition on electronic circuits with surface mounted chips (SMCs) andalso on small television sets. One set of electronics was exposed for 281h to an unusually high concentration of artificially-generated ammoniumsulfate particles while a second set (experimental controls) was exposedto normal indoor particles. The particle mass concentration in thehigh-exposure chamber was 500 times higher than normal. Televisionreliability was observed and the changes in EI between adjacent legs ofSMCs were measured. The experiments demonstrate the strong influence ofelectrostatic forces on the locations and rates of particle deposition.Although televisions did not fail after exposure to concentratedaerosols, the EI between adjacent legs of the SMCs was, in many cases,greatly diminished. Relative humidity had a very strong influence on themagnitude of EI. A qualitative explanation of the mechanisms of particledeposition and circuit degradation is proposed, including the role offibers. Finally, a potential method to reduce particle deposition onelectronic components is discussed
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Saving energy and improving IAQ through application of advanced air cleaning technologies
In the future, we may be able use air cleaning systems and reduce rates of ventilation (i.e., reduce rates of outdoor air supply) to save energy, with indoor air quality (IAQ) remaining constant or even improved. The opportunity is greatest for commercial buildings because they usually have a narrower range of indoor pollutant sources than homes. This article describes the types of air cleaning systems that will be needed in commercial buildings
A New Unconventional Antiferromagnet, YbPt
We report the synthesis and basic properties of single crystals of a new
binary compound, YbPt. The Yb ions in this compound are fully
trivalent, and heat capacity measurements show that the crystal field scheme
involves a doublet ground state, well separated from the excited states, which
are fully occupied above 150 K. The heat capacity displays a large,
weakly first order anomaly at 2.4 K, where a cusp is observed in the magnetic
susceptibility signalling the onset of antiferromagnetic order. The entropy
associated with this order is the full Rln2 of the doublet ground state,
however the magnetic susceptibility in the ordered phase is dominated by a
large and temperature independent component below the Neel temperature. The
heat capacity in the ordered state originates with ferromagnetic spin waves,
giving evidence for the inherently local moment character of the ordered state.
The electrical resistivity is unusually large, and becomes quadratic in
temperature exactly at the Neel temperature. The absence of analogous Fermi
liquid behavior in the heat capacity and the magnetic susceptibility implies
that YbPt is a low electron density system, where the Fermi surface
is further gapped by the onset of magnetic order.Comment: 8 pages, 9 figure
A Precise Measurement of the Weak Mixing Angle in Neutrino-Nucleon Scattering
We report a precise measurement of the weak mixing angle from the ratio of
neutral current to charged current inclusive cross-sections in deep-inelastic
neutrino-nucleon scattering. The data were gathered at the CCFR neutrino
detector in the Fermilab quadrupole-triplet neutrino beam, with neutrino
energies up to 600 GeV. Using the on-shell definition, , we obtain .Comment: 10 pages, Nevis Preprint #1498 (Submitted to Phys. Rev. Lett.
The Intentional Use of Service Recovery Strategies to Influence Consumer Emotion, Cognition and Behaviour
Service recovery strategies have been identified as a critical factor in the success of. service organizations. This study develops a conceptual frame work to investigate how specific service recovery strategies influence the emotional, cognitive and negative behavioural responses of . consumers., as well as how emotion and cognition influence negative behavior. Understanding the impact of specific service recovery strategies will allow service providers' to more deliberately and intentionally engage in strategies that result in positive organizational outcomes. This study was conducted using a 2 x 2 between-subjects quasi-experimental design. The results suggest that service recovery has a significant impact on emotion, cognition and negative behavior. Similarly, satisfaction, negative emotion and positive emotion all influence negative behavior but distributive justice has no effect
Measurement of W Polarisation at LEP
The three different helicity states of W bosons produced in the reaction e+
e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W
decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to
measure the polarisation of W bosons, and its dependence on the W boson
production angle. The fraction of longitudinally polarised W bosons is measured
to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and
the second systematic, in agreement with the Standard Model expectation
Search for Anomalous Couplings in the Higgs Sector at LEP
Anomalous couplings of the Higgs boson are searched for through the processes
e^+ e^- -> H gamma, e^+ e^- -> e^+ e^- H and e^+ e^- -> HZ. The mass range 70
GeV < m_H < 190 GeV is explored using 602 pb^-1 of integrated luminosity
collected with the L3 detector at LEP at centre-of-mass energies
sqrt(s)=189-209 GeV. The Higgs decay channels H -> ffbar, H -> gamma gamma, H
-> Z\gamma and H -> WW^(*) are considered and no evidence is found for
anomalous Higgs production or decay. Limits on the anomalous couplings d, db,
Delta(g1z), Delta(kappa_gamma) and xi^2 are derived as well as limits on the H
-> gamma gamma and H -> Z gamma decay rates
Measurement of W Polarisation at LEP
The three different helicity states of W bosons produced in the reaction e+
e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W
decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to
measure the polarisation of W bosons, and its dependence on the W boson
production angle. The fraction of longitudinally polarised W bosons is measured
to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and
the second systematic, in agreement with the Standard Model expectation
Neutral-Current Four-Fermion Production in e+e- Interactions at LEP
Neutral-current four-fermion production, e+e- -> ffff is studied in 0.7/fb of
data collected with the L3 detector at LEP at centre-of-mass energies
root(s)=183-209GeV. Four final states are considered: qqvv, qqll, llll and
llvv, where l denotes either an electron or a muon. Their cross sections are
measured and found to agree with the Standard Model predictions. In addition,
the e+e- -> Zgamma* -> ffff process is studied and its total cross section at
the average centre-of-mass energy 196.6GeV is found to be 0.29 +/- 0.05 +/-
0.03 pb, where the first uncertainty is statistical and the second systematic,
in agreement with the Standard Model prediction of 0.22 pb. Finally, the mass
spectra of the qqll final states are analysed to search for the possible
production of a new neutral heavy particle, for which no evidence is found
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