711 research outputs found
Voluntary agreements to achieve energy efficiency, a comparison between China and The Netherlands
China has gained experience with voluntary agreements. In this paper the experiences in China will be analysed and compared to the factors contributing to the success of this model in the Netherlands. Are voluntary agreements an alternative for the Chinese command and control system? We distinguish different types of voluntary agreements and compare those in China and the Netherlands on a number of dimensions. The hypothesis is tested that voluntary agreements are more effective in achieving pollution control than the traditional command and control approach. It is found that indeed most voluntary agreements score good in China as well as in the Netherlands on a number of chosen indicators. Voluntary agreements are effective in achieving ambitious energy saving targets in a flexible and cost-effective way. Voluntary agreements have the function to mobilise support for energy saving, which is not easily mobilised through the traditional command-and-control approaches. There are however some important differences between the functioning of the system in China and in the Netherlands, where a more bottom-up approach is common. The Netherlands has a tradition of stakeholders' involvement and experience over a longer time of monitoring the effectiveness of the project and adjusting them if necessary
Measuring urban resilience to climate change in three chinese cities
Building an urban resilience index results in developing an increasingly popular tool for monitoring progress towards climate-proof cities. This paper develops an urban resilience index in the context of urban China, which helps planners and policy-makers
Observation of in
Using a sample of events recorded with
the BESIII detector at the symmetric electron positron collider BEPCII, we
report the observation of the decay of the charmonium state
into a pair of mesons in the process
. The branching fraction is measured for the first
time to be , where the first uncertainty is
statistical, the second systematic and the third is from the uncertainty of
. The mass and width of the are
determined as MeV/ and
MeV.Comment: 13 pages, 6 figure
Observation and study of the decay
We report the observation and study of the decay
using events
collected with the BESIII detector. Its branching fraction, including all
possible intermediate states, is measured to be
. We also report evidence for a structure,
denoted as , in the mass spectrum in the GeV/
region. Using two decay modes of the meson ( and
), a simultaneous fit to the mass spectra is
performed. Assuming the quantum numbers of the to be , its
significance is found to be 4.4, with a mass and width of MeV/ and MeV, respectively, and a
product branching fraction
. Alternatively, assuming , the
significance is 3.8, with a mass and width of MeV/ and MeV, respectively, and a product
branching fraction
. The angular distribution of
is studied and the two assumptions of the
cannot be clearly distinguished due to the limited statistics. In all
measurements the first uncertainties are statistical and the second systematic.Comment: 10 pages, 6 figures and 4 table
Observation of and confirmation of its large branching fraction
The baryonic decay is observed, and the
corresponding branching fraction is measured to be
, where the first uncertainty is statistical
and second systematic. The data sample used in this analysis was collected with
the BESIII detector operating at the BEPCII double-ring collider with
a center-of-mass energy of 4.178~GeV and an integrated luminosity of
3.19~fb. The result confirms the previous measurement by the CLEO
Collaboration and is of greatly improved precision, which may deepen our
understanding of the dynamical enhancement of the W-annihilation topology in
the charmed meson decays
Search for the decay
We search for radiative decays into a weakly interacting neutral
particle, namely an invisible particle, using the produced through the
process in a data sample of
decays collected by the BESIII detector
at BEPCII. No significant signal is observed. Using a modified frequentist
method, upper limits on the branching fractions are set under different
assumptions of invisible particle masses up to 1.2 . The upper limit corresponding to an invisible particle with zero mass
is 7.0 at the 90\% confidence level
First observations of hadrons
Based on events collected with
the BESIII detector, five hadronic decays are searched for via process
. Three of them, ,
, and are observed for the first
time, with statistical significances of 7.4, , and
9.1, and branching fractions of ,
, and ,
respectively, where the first uncertainties are statistical and the second
systematic. No significant signal is observed for the other two decay modes,
and the corresponding upper limits of the branching fractions are determined to
be and at 90% confidence level.Comment: 17 pages, 16 figure
Observation of and Improved Measurements of
Using a data sample corresponding to an integrated luminosity of
2.93~fb recorded by the BESIII detector at a center-of-mass energy of
GeV, we present an analysis of the decays and . By performing a partial wave
analysis, the -wave contribution to
is observed to be % with a statistical significance greater
than 10, besides the dominant -wave contribution. This is the first
observation of the -wave contribution. We measure the branching fractions
, , and . An upper limit
of is set at the 90% confidence level. We also obtain the hadronic
form factor ratios of at assuming the
single-pole dominance parameterization:
,
Evidence for the decays of and
We study the hadronic decays of to the final states
and , using an annihilation
data sample of 567 pb taken at a center-of-mass energy of 4.6 GeV with
the BESIII detector at the BEPCII collider. We find evidence for the decays
and with
statistical significance of and , respectively.
Normalizing to the reference decays and
, we obtain the ratios of the branching fractions
and to be and , respectively. The upper limits at the 90\% confidence level are
set to be and . Using BESIII measurements of the
branching fractions of the reference decays, we determine
() and
(). Here, the first uncertainties are statistical and the second
systematic. The obtained branching fraction of is
consistent with the previous measurement, and the branching fraction of
is measured for the first
time.Comment: Accepted by Chin. Phys. C : Chin. Phys. C 43, 083002, (2019
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