794 research outputs found
Black-odorous water bodies annual dynamics in the context of climate change adaptation in Guangzhou City, China
Black-odorous water (BOW) in urban areas has brought detrimental ecological effects and posed a threat to the health of surrounding residents. Identifying BOWs in urban areas is difficult because they are usually small in area, and discontinuous in spatial distribution. The efforts to adapt to climate change in cities have a direct connection to urban environment and may affect the dynamics of BOWs, but their relationship has seldom been addressed in previous research. This research builds a new urban BOW detection model using Gaofen (GF) images and ground-level in-situ water quality data to detect the spatiotemporal dynamics of BOWs in Guangzhou City's main urban area from 2016 to 2020, when comprehensive climate adaptation strategy has been implemented as a pilot metropolitan area in China. Spatial analysis in the study area with a total of 97 focused rivers revealed a decreasing trend in BOW occurrence (from 85.57% in 2016 to 21.65% in 2020) in the context of climate change adaptation efforts. Redundancy analysis between BOWs occurrence and environmental factors showed that across the entire study area, the contributions of anthropogenic factors (highest proportion at 14.3% for the area percentage of built-ups) to BOW, such as population density, agricultural water use, domestic water use, and so on, distinctly stronger than climatic drivers (largest contribution of 4.4% for temperature). The results suggested that climate change adaptation efforts help to decrease BOW occurrence in the study area, while exploring the response mechanism between climate change adaptation measures and the changes of BOWs is necessary in the future research. The findings were conducive to the development of targeted measures to decrease the occurrence of urban BOWs while improving adaptability of the city to climate change
Seasonal occurrence and species specificity of fishy and musty odor in Huajiang Reservoir in winter, China
AbstractThis paper describes the results of measurements from one year period on the existence of fishy and musty odor in drinking water at low temperatures (1–2°C) in Baotou, China, using an open-loop stripping analysis (OLSA) systems and Gas chromatography spectrometry (GC). The main results show that it is micro-contaminated water body of the raw water in Huajiang Reservoir. The average phytoplankton abundance was 2.06×107L−1, Cyanobacteria counts were at 2.0×106L−1 and the dominate family of the algae are Chlorophyta, Cryptophyta, and Bacillariophyta. Experimental results indicated that under the ice whose thickness was 0.55m, the photosynthetically active radiation (PAR) of the surface varied from 70 to 636Wm−2 from November to March of next year. The average surface PAR was 114.8Wm−2, and the lowest value was 70.57Wm−2 (in December) and the average bottom PAR was 19.04Wm−2, and the lowest value was 3.84Wm−2 (in December). The surface PAR, bottom PAR, eutrophic conditions in ice-covered Huajiang reservoir satisfied the growth and MIB/geosmin production of Cyanobacteria algae in winter. The 2-methyl-isoborneol (MIB) concentration ranged from 29ngL−1 to 102ngL−1. The concentration of trans-1,10-dimethyl-trans-9-decalol (geosmin) ranges from 20ngL−1 to 65ngL−1 and it is 2 to 5 times of the odor threshold concentrations (OTC). The correlations between MIB/geosmin and nitrogen are 0.63–0.37. Eutrophication is the most important factor influencing synthesis of taste and odors, but not temperature. Using bypassing pipe pumping Yellow River water directly to the Water treatment plant (WTP) is an efficient way about T&O compounds׳ control in drinking water of Baotou city in winter
A novel measurement of and lifetimes using semileptonic decays at LHCb
I report new, world-leading LHCb results on heavy meson lifetimes. We use a
novel approach that suppresses the shortcomings typically associated with
reconstruction of semileptonic decays, allowing for precise measurements of
lifetimes and other properties in collider experiments. We achieve a 15% and a
improvement over current best determinations of the flavor-specific
lifetime and lifetime, respectively.Comment: 12 pages, 6 figures. Talk presented at the APS Division of Particles
and Fields Meeting (DPF 2017), July 31-August 4, 2017, Fermilab. C17073
Noise suppression of on-chip mechanical resonators by chaotic coherent feedback
We propose a method to decouple the nanomechanical resonator in
optomechanical systems from the environmental noise by introducing a chaotic
coherent feedback loop. We find that the chaotic controller in the feedback
loop can modulate the dynamics of the controlled optomechanical system and
induce a broadband response of the mechanical mode. This broadband response of
the mechanical mode will cut off the coupling between the mechanical mode and
the environment and thus suppress the environmental noise of the mechanical
modes. As an application, we use the protected optomechanical system to act as
a quantum memory. It's shown that the noise-decoupled optomechanical quantum
memory is efficient for storing information transferred from coherent or
squeezed light
Testing the Bell Inequality at Experiments of High Energy Physics
Besides using the laser beam, it is very tempting to directly testify the
Bell inequality at high energy experiments where the spin correlation is
exactly what the original Bell inequality investigates. In this work, we follow
the proposal raised in literature and use the successive decays
to testify
the Bell inequality. Our goal is twofold, namely, we first make a Monte-Carlo
simulation of the processes based on the quantum field theory (QFT). Since the
underlying theory is QFT, it implies that we pre-admit the validity of quantum
picture. Even though the QFT is true, we need to find how big the database
should be, so that we can clearly show deviations of the correlation from the
Bell inequality determined by the local hidden variable theory. There have been
some critiques on the proposed method, so in the second part, we suggest some
improvements which may help to remedy the ambiguities indicated by the
critiques. It may be realized at an updated facility of high energy physics,
such as BES III.Comment: 16 pages, 5 figure
- …