6,273 research outputs found
Assessing photochemical ozone formation in the Pearl River Delta with a photochemical trajectory model
A photochemical trajectory model (PTM), coupled with the Master Chemical Mechanism (MCM) describing the degradation of 139 volatile organic compounds (VOCs) in the troposphere, was developed and used for the first time to simulate the formation of photochemical pollutants at Wangqingsha (WQS), Guangzhou during photochemical pollution episodes between 12 and 17 November, 2007. The simulated diurnal variations and mixing ratios of ozone were in good agreement with observed data (R2=0.80, P<0.05), indicating that the photochemical trajectory model - an integration of boundary layer trajectories, precursor emissions and chemical processing - provides a reasonable description of ozone formation in the Pearl River Delta (PRD) region. Calculated photochemical ozone creation potential (POCP) indices for the region indicated that alkanes and oxygenated organic compounds had relatively low reactivity, while alkenes and aromatics presented high reactivity, as seen in other airsheds in Europe. Analysis of the emission inventory found that the sum of 60 of the 139 VOC species accounted for 92% of the total POCP-weighted emission. The 60 VOC species include C2-C6 alkenes, C6-C8 aromatics, biogenic VOCs, and so on. The results indicated that regional scale ozone formation in the PRD region can be mainly attributed to a relatively small number of VOC species, namely isoprene, ethene, m-xylene, and toluene, etc. A further investigation of the relative contribution of the main emission source categories to ozone formation suggested that mobile sources were the largest contributor to regional O3 formation (40%), followed by biogenic sources (29%), VOC product-related sources (23%), industry (6%), biomass burning (1%), and power plants (1%). The findings obtained in this study would advance our knowledge of air quality in the PRD region, and provide useful information to local government on effective control of photochemical smog in the region. © 2010 Elsevier Ltd
A numerical study of the impact of climate and emission changes on surface ozone over South China in Autumn time in 2000-2050
2012-2013 > Academic research: refereed > Publication in refereed journalAccepted ManuscriptPublishe
Game for Complete Care: A Means of Connecting ‘User-Centered Design’ with Sustainability
Copyright © 2021 The Author(s). This paper addresses sustainability and gaming from an interior design education perspective, emphasizing the importance of understanding the meaning of ‘complete care’ and raising the awareness of care among design students. The four-step inquiry was adopted as a methodological framework. The theoretical model of ‘complete care’ was proposed and the interactive game ‘Ideal Home’ was developed to raise the awareness of care in design. The game imitated a conversation activity between the interior designer and the client at the early stage of the design process and assisted ‘designers’ to ask meaningful questions from ‘clients’ so as to develop a better understanding of their care needs. Six postgraduate students with interior design backgrounds played the game, and they were observed and interviewed. The results suggested that the participants’ understanding of care improved after they played the game and they were able to identify more issues and detailed needs through the conversations. The significance of the research is that it proposes a theoretical framework to explain the meaning of ‘complete care’ in the design process, and also develops a practical tool (i.e., the game) to educate designers about care.Tongji-Hong Kong PolyU PhD Scholarship scheme; Fundamental Research Funding of Central Universities of China; Brunel University London’s Open Access FundTongji-Hong Kong PolyU PhD Scholarship scheme; Fundamental Research Funding of Central Universities of China, Ref No. 222202022040; Brunel University London’s Open Access Funding
Electronic measurement and control of spin transport in Silicon
The electron spin lifetime and diffusion length are transport parameters that
define the scale of coherence in spintronic devices and circuits. Since these
parameters are many orders of magnitude larger in semiconductors than in
metals, semiconductors could be the most suitable for spintronics. Thus far,
spin transport has only been measured in direct-bandgap semiconductors or in
combination with magnetic semiconductors, excluding a wide range of
non-magnetic semiconductors with indirect bandgaps. Most notable in this group
is silicon (Si), which (in addition to its market entrenchment in electronics)
has long been predicted a superior semiconductor for spintronics with enhanced
lifetime and diffusion length due to low spin-orbit scattering and lattice
inversion symmetry. Despite its exciting promise, a demonstration of coherent
spin transport in Si has remained elusive, because most experiments focused on
magnetoresistive devices; these methods fail because of universal impedance
mismatch obstacles, and are obscured by Lorentz magnetoresistance and Hall
effects. Here we demonstrate conduction band spin transport across 10 microns
undoped Si, by using spin-dependent ballistic hot-electron filtering through
ferromagnetic thin films for both spin-injection and detection. Not based on
magnetoresistance, the hot electron spin-injection and detection avoids
impedance mismatch issues and prevents interference from parasitic effects. The
clean collector current thus shows independent magnetic and electrical control
of spin precession and confirms spin coherent drift in the conduction band of
silicon.Comment: Single PDF file with 4 Figure
Automatic Frame Selection Using MLP Neural Network in Ultrasound Elastography
Ultrasound elastography estimates the mechanical properties of the tissue
from two Radio-Frequency (RF) frames collected before and after tissue
deformation due to an external or internal force. This work focuses on strain
imaging in quasi-static elastography, where the tissue undergoes slow
deformations and strain images are estimated as a surrogate for elasticity
modulus. The quality of the strain image depends heavily on the underlying
deformation, and even the best strain estimation algorithms cannot estimate a
good strain image if the underlying deformation is not suitable. Herein, we
introduce a new method for tracking the RF frames and selecting automatically
the best possible pair. We achieve this by decomposing the axial displacement
image into a linear combination of principal components (which are calculated
offline) multiplied by their corresponding weights. We then use the calculated
weights as the input feature vector to a multi-layer perceptron (MLP)
classifier. The output is a binary decision, either 1 which refers to good
frames, or 0 which refers to bad frames. Our MLP model is trained on in-vivo
dataset and tested on different datasets of both in-vivo and phantom data.
Results show that by using our technique, we would be able to achieve higher
quality strain images compared to the traditional methods of picking up pairs
that are 1, 2 or 3 frames apart. The training phase of our algorithm is
computationally expensive and takes few hours, but it is only done once. The
testing phase chooses the optimal pair of frames in only 1.9 ms
Hepatitis B Virus Core Promoter Double Mutations (A1762T, G1764A) Are Associated with Lower Levels of Serum Dihydrolipoyl Dehydrogenase
Published by S. Karger AG, BaselObjectives: The aim of this study was to identify serum proteins with differential concentrations between hepatocellular carcinoma (HCC) patients and HBsAg asymptomatic carriers among individuals infected with hepatitis B virus (HBV) with basal core promoter (BCP) double mutations (A1762T, G1764A). Methods: iTRAQ and liquid chromatography-tandem mass spectrometry were used to identify differentially expressed protein, and an ELISA test was used for the validation test. Results: The total number of proteins identified was 1,125, of which 239 showed statistically significant differences in their expression. The relative concentrations of serum dihydrolipoyl dehydrogenase (DLD), which showed the most significant correlation with liver diseases and infection, were significantly lower in HCC patients than asymptomatic HBsAg carriers and individuals negative for HBsAg. However, only the difference between HCC patients with BCP double mutations and HBsAg-negative individuals could be confirmed by ELISA. Meanwhile, we found that the concentrations of serum DLD in those infected with HBV with BCP double mutations were significantly lower than in individuals with the wild-type BCP. However, the difference in the concentrations of serum DLD between individuals with wild-type BCP and those negative for HBsAg was not significant. Conclusions: HBV with BCP double mutations are associated with lower concentrations of serum DLD
Spectral Line-by-Line Pulse Shaping of an On-Chip Microresonator Frequency Comb
We report, for the first time to the best of our knowledge, spectral phase
characterization and line-by-line pulse shaping of an optical frequency comb
generated by nonlinear wave mixing in a microring resonator. Through
programmable pulse shaping the comb is compressed into a train of
near-transform-limited pulses of \approx 300 fs duration (intensity full width
half maximum) at 595 GHz repetition rate. An additional, simple example of
optical arbitrary waveform generation is presented. The ability to characterize
and then stably compress the frequency comb provides new data on the stability
of the spectral phase and suggests that random relative frequency shifts due to
uncorrelated variations of frequency dependent phase are at or below the 100
microHertz level.Comment: 18 pages, 4 figure
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