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1.
Artigo em Inglês | MEDLINE | ID: mdl-32305923

RESUMO

Sketches in existing large-scale datasets like the recent QuickDraw collection are often stored in a vector format, with strokes consisting of sequentially sampled points. However, most existing sketch recognition methods rasterize vector sketches as binary images and then adopt image classification techniques. In this paper, we propose a novel end-to-end single-branch network architecture RNN-Rasterization-CNN (Sketch-R2CNN for short) to fully leverage the vector format of sketches for recognition. Sketch-R2CNN takes a vector sketch as input and uses an RNN for extracting per-point features in the vector space. We then develop a neural line rasterization module to convert the vector sketch and the per-point features to multi-channel point feature maps, which are subsequently fed to a CNN for extracting convolutional features in the pixel space. Our neural line rasterization module is designed in a differentiable way for end-to-end learning. We perform experiments on existing large-scale sketch recognition datasets and show that the RNN-Rasterization design brings consistent improvement over CNN baselines and that Sketch-R2CNN substantially outperforms the state-of-the-art methods.

2.
Macromol Biosci ; 20(5): e1900360, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32237050

RESUMO

Local, micromechanical environment is known to influence cellular function in heterogeneous hydrogels, and knowledge gained in micromechanics will facilitate the improved design of biomaterials for tissue regeneration. In this study, a system comprising microstructured resilin-like polypeptide (RLP)-poly(ethylene glycol) (PEG) hydrogels is utilized. The micromechanical properties of RLP-PEG hydrogels are evaluated with oscillatory shear rheometry, compression dynamic mechanic analysis, small-strain microindentation, and large-strain indentation and puncture over a range of different deformation length scales. The measured elastic moduli are consistent with volume averaging models, indicating that volume fraction, not domain size, plays a dominant role in determining the low strain mechanical response. Large-strain indentation under a confocal microscope enables the visualization of the microstructured hydrogel micromechanical deformation, emphasizing the translation, rotation, and deformation of RLP-rich domains. The fracture initiation energy results demonstrate that failure of the composite hydrogels is controlled by the RLP-rich phase, and their independence with domain size suggested that failure initiation is controlled by multiple domains within the strained volume. This approach and findings provide new quantitative insight into the micromechanical response of soft hydrogel composites and highlight the opportunities in employing these methods to understand the physical origins of mechanical properties of soft synthetic and biological materials.

3.
Chemosphere ; 253: 126491, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32278901

RESUMO

China has experienced severe acid rain pollution during the past decades due to excessive sulfur oxides (SO2) and nitrous oxides (NOx) emissions, which further caused lake acidification, biodiversity losses and climate change. Although the major sources of acid deposition have been clarified previously, the contributions of socioeconomic (natural) factors to the regional acid deposition remained unknown. Therefore, a series of valuable data including socioeconomic (natural) variables and measured pH value in the rainwater at the city level were collected to identify the key factors influencing the rainwater pH value at the national and the regional scale using the spatial econometric model/geographical detector technique and geographical weight regression (GWR) model, respectively. The results showed that the annual mean pH value in the rainwater in China was 6.54 ± 0.72. The rainwater pH in winter (6.01 ± 0.41) was significantly lower than those observed during summer (6.74 ± 0.64), spring (6.71 ± 0.71) and autumn (6.71 ± 0.69). The spatial econometric model indicated that socioeconomic indicators including per capita gross industrial production (GIP), ratio of built-up area to the urban land (RBU), foreign direct investment (FDI), SO2 emission, and meteorological factors of annual mean precipitation (AMP), and annual mean relative humidity (AMRH) were the main factors for the acid deposition. The geographical detector technique implied that the power of determinants were in the order of AMRH (10.00%) = AMP (10.00%) > SO2 emission (8.51%) > FDI (8.32%) > RBU (7.64%) > per capita GIP (7.00%). The GWR implied that GIP, FDI, and SO2 emission made relatively higher contribution to acid deposition in East China relative to other regions owning to the huge population and the higher energy consumption. The higher rainfall amount and RH in Southeast China significantly increased the pollutant deposition fluxes and promoted the heterogeneous transformations of precursors of acid rain, respectively. The findings herein shed light upon the socioeconomic forces for the acid deposition in China for the first time and provided the new information for government sectors to control the acid rain pollution in the future.


Assuntos
Chuva Ácida , Poluição do Ar/estatística & dados numéricos , Monitoramento Ambiental , Poluentes Atmosféricos/análise , Poluição do Ar/análise , China , Cidades , Mudança Climática , Poluição Ambiental , Estações do Ano , Fatores Socioeconômicos
4.
Artigo em Inglês | MEDLINE | ID: mdl-31985423

RESUMO

We present DeepSketchHair, a deep learning based tool for interactive modeling of 3D hair from 2D sketches. Given a 3D bust model as reference, our sketching system takes as input a user-drawn sketch (consisting of hair contour and a few strokes indicating the hair growing direction within a hair region), and automatically generates a 3D hair model, which matches the input sketch both globally and locally. The key enablers of our system are two carefully designed neural networks, namely, S2ONet, which converts an input sketch to a dense 2D hair orientation field; and O2VNet, which maps the 2D orientation field to a 3D vector field. Our system also supports hair editing with additional sketches in new views. This is enabled by another deep neural network, V2VNet, which updates the 3D vector field with respect to the new sketches. All the three networks are trained with synthetic data generated from a 3D hairstyle database. We demonstrate the effectiveness and expressiveness of our tool using a variety of hairstyles and also compare our method with prior art.

5.
Chemosphere ; 247: 125839, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31955041

RESUMO

Ambient SO2 pollution poses a great threat on air quality, human health, and ecosystem safety. The ground-level SO2 monitoring sites over China have been established during the past years, while the long-term SO2 data was still missing before 2014, which cannot reveal the evolution trend of SO2 pollution and assess its response to the anthropogenic activity. In this work, we developed a high-quality random forest (RF) model to simulate the long-term SO2 concentration across the entire China from 1973 to 2014, based on substantial explanatory variables (e.g., meteorological factors, SO2 emission intensity, land use types). The 10-fold cross-validation R2 value and root mean square error (RMSE) over China reached 0.64 and 17.06 µg/m3, respectively, both of which were significantly higher than those of other models such as back propagation neural network (BPNN) and generalized regression neutral network (GRNN). Among all of the predictors, T displayed the highest relative importance value, followed by WS, Prec, SO2 emission intensity, RH, DOY, elevation, and the lower one for land use types and P. The estimated mean SO2 concentration during 1973-2014 displayed the remarkably spatial variation with the higher value in North China Plain (NCP) and Middle part of Inner Mongolia. This historical SO2 level estimation suggested that air pollution was not a new environmental issue that could be dated back to 1973. Overall, the annually mean SO2 level for each grid increased from 29.46 ± 9.79 to 31.44 ± 8.77 µg/m3 from 1973 to 2014. The annually mean SO2 concentration in NCP showed rapid increase from 34.32 ± 3.05 to 36.97 ± 3.18 µg/m3 during 1973-2002, whereas they decreased significantly after 2003 (from 37.46 ± 3.20 to 36.13 ± 3.48 µg/m3 during 2003-2014). The gradual decrease since 2003 was benefitted from the adjustment of the energy consumption structure and the adoption of emission control technologies. However, the SO2 levels in some western regions showed the violent increases since 2003 due to the proposal of "development of the western region". The estimated daily SO2 concentration across the entire China could provide the essential data for epidemiological research and air pollution prevention.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Modelos Estatísticos , Dióxido de Enxofre/análise , Poluição do Ar/análise , China , Ecossistema , Exposição Ambiental/análise , Poluição Ambiental/análise , História do Século XX , História do Século XXI , Humanos , Material Particulado/análise , Dióxido de Enxofre/história
6.
Chemosphere ; 241: 125031, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31610459

RESUMO

Severe air pollution episodes with high SO2 loading have been frequently observed during the last decades in Beijing and have caused a noticeable damage to human health. To advance the spatiotemporal prediction of SO2 exposure in Beijing, we developed the monthly land use regression (LUR) models using daily SO2 concentration data collected from 34 monitoring stations during 2016 and 7 categories of potential independent variables (socio-economic factors, traffic and transport, emission source, land use, meteorological data, building morphology and Geographic location) in Beijing. The average adjusted R2 of 12 final LUR models was 0.62, and the root-mean-squared error (RMSE) was 4.12 µg/m3. The LOOCV R2 and RMSE of LUR models reached 0.56 and 5.43 µg/m3, respectively, suggesting that the LUR models achieved the satisfactory performance. The prediction results suggested that the average SO2 level in Beijing was 11.06 µg/m3 with the highest one up to 22.49 µg/m3 but the lowest one down to 3.86 µg/m3. The SO2 exposure showed strong spatial heterogeneity, which was much higher in the southern area than that in the northern in Beijing. The mortality and morbidity due to the excessive SO2 concentration were estimated to be 73 (95% CI:(38-125)) and 27854 (95% CI:(13852-41659)) cases per year in Beijing, leading to economic cost of 35.76 (95% CI:(16.45-54.06)) and 441.47 (95% CI:(318.31-562.04)) million RMB Yuan in 2016, respectively. This study clarified the intra- and inter-regional transport modeling of the SO2 pollution in Beijing and supplied an important support for the future air-quality and public health management strategies.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Dióxido de Enxofre/análise , Poluição do Ar/análise , Pequim , Humanos , Mortalidade , Material Particulado/análise , Análise Espaço-Temporal , Dióxido de Enxofre/economia , Dióxido de Enxofre/uso terapêutico
7.
Analyst ; 145(1): 277-285, 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-31746822

RESUMO

Detecting atmospheric bioaerosols in a quantitative way is highly desirable for public health and safety. This work demonstrates that surface-enhanced Raman spectroscopy (SERS) is a simple and rapid analytical technique for the detection of atmospheric bioaerosols, on a Klarite substrate. For both simulated and ambient bioaerosols, this detection assay results in an increase in the enhancement factor of the Raman signal. We report a strong SERS signal generated by bioaerosols containing living Escherichia coli deposited on Klarite. Furthermore, we demonstrate that SERS mapping can be used to estimate the percentage of airborne, living Escherichia coli. Moreover, Klarite provides differently distinct SERS spectra at different bacterial growth phases, indicating its potential to identify changes occurring in the bacterial envelope. Finally, we applied SERS for the rapid detection of Escherichia coli in ambient bioaerosols without using time-consuming and laborious culture processes. Our results represent rapid, culture-free and label-free detection of airborne bacteria in the real-world environment.

8.
Artigo em Inglês | MEDLINE | ID: mdl-31751244

RESUMO

Specifying precise relationships among graphic elements is often a time-consuming process with traditional alignment tools. Automatic beautification of roughly designed layouts can provide a more efficient solution but often lead to undesired results due to ambiguity problems. To facilitate ambiguity resolution in layout beautification, we present a novel user interface for visualizing and editing inferred relationships through an automatic global layout beautification process. First, our interface provides a preview of the beautified layout with inferred constraints without directly modifying an input layout. In this way, the user can easily keep refining beautification results by interactively repositioning and/or resizing elements in the input layout. Second, we present a gestural interface for editing automatically inferred constraints by directly interacting with the visualized constraints via simple gestures. Our technique is applicable to both 2D and 3D global layout beautification, supported by efficient system implementation that provides instant user feedback. Our user study validates that our tool is capable of creating, editing and refining layouts of graphic elements, and is significantly faster than the standard snap-dragging or command-based alignment tools for both 2D and 3D layout tasks.

9.
Sci Total Environ ; 687: 1073-1086, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31412445

RESUMO

Fine particle explosive growth (FPEG) events are frequently observed in heavy haze episodes in Beijing, the characteristics and formation mechanism of which remain not fully understood. In this study, a five year (2013-2017) online observation was conducted in Beijing and the chemical evolution pattern of FPEG events was analyzed to understand its formation mechanism. A total of 132 FPEG events were identified, and steadily decreased from 39 events in 2013 to 19 events in 2017. More than 70% of the FPEG events occurred in winter and autumn, which coincides with adverse weather conditions and enhanced primary emissions. Organic matter (OM) was the dominated components (~30%) in PM2.5, but it only accounted for 10% of total FPEG events as a driven factor, because its contribution usually decreased when the FPEG events developed. In contrast, the secondary inorganic species were the dominated driven factors, and sulfate-driven events accounted >50%. During the period of 2013-2017, the contribution from regional sources decreased significantly mainly due to the reduction of emissions from regional sources, while the contribution from local sources remained largely unchanged, indicating that the local secondary transformation played a leading role in promoting the FPEG events. The low nitrogen oxidation rates (NOR, 0.12 ±â€¯0.07) and the weak increase trend of NOR with elevated RH were observed, indicating the formation of which might be promoted by the homogenous reaction between HNO3 and NH3. In contrast, a significant increase in sulfur oxidation rate (SOR, 0.50 ±â€¯0.19) was observed when RH > 50%, suggesting enhanced heterogeneous oxidation of SO2 in FPEG events. In addition, our analysis suggest the S (IV) heterogeneous oxidation rates in FPEG events depend mainly on the aerosol liquid water content (ALWC) in addition to the aerosol acidity. This study provides observational evidence for understanding the formation mechanism of FPEG events in Beijing.

10.
Environ Sci Technol ; 53(17): 10361-10370, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31390862

RESUMO

"Ultralow-emission" standards have started to be implemented for steel plants in China. Flue gas desulfurization (FGD) systems integrating desulfurization and dedusting, common end-of-pipe technologies before the stacks, have been a key process for controlling the complexity of sintering flue gas to meet ultralow-emission requirements. This study reports comprehensive analysis of the influence of wet/semidry/dry FGD systems on particulate emissions via a field investigation of five typical sinter plants equipped with various FGD devices. The size distribution and mass concentration of particulate matter (PM) are adjusted to different ranges by these FGD systems. Chemical analysis of the PM compositions shows that 20-95% of the mass of inlet PM is removed by FGD systems, while it is estimated that approximately 17, 63, 59, and 71% of the outlet PMs are newly contributed by desulfurizers and their byproducts for the tested wet limestone, wet ammonia, semidry circulating fluidized bed, and activated coke FGD systems, respectively. The newly contributed compositions of PM2.5 emitted from these FGD systems are dominated by CaSO4, (NH4)2SO4, CaSO4 + CaO, and coke carbon, respectively. These results suggest that the deployment of FGD technology should be comprehensively considered to avoid additional negative impacts from byproducts generated in control devices on the atmosphere.


Assuntos
Poluentes Atmosféricos , Aço , China , Carvão Mineral , Material Particulado
11.
Environ Pollut ; 254(Pt A): 112941, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31377330

RESUMO

China continues to suffer from severe acid deposition, despite the government implying a series of policies to control air pollution. In this study, rainwater samples were collected from 2011 to 2016 in Sichuan province to measure the pH values and the concentrations of nine inorganic ions (SO42-, NO3-, NH4+, Cl-, Na+, Ca2+, K+, Mg2+, and F-), and then to investigate their spatiotemporal variations. Besides, the dominant sources for the acidic ions in the precipitation were also revealed by statistical model. The results showed that the rainwater continued to be highly acidic, and the Volume-Weighted Mean (VWM) pH value was calculated to be 5.18 during 2011 and 2016. NH4+, Ca2+, NO3-, and SO42- were the dominant water-soluble inorganic ions, accounting for 79.2% of the total ions on average. The remarkable decrease in NO3- and SO42- concentrations (from 75.9 to 54.3 µeq L-1 and from 285 to 145 µeq L-1, respectively) resulted in an increase in the pH value of rainwater from 5.24 in 2011 to 5.70 in 2016. The concentrations of SO42-, NO3-, F-, Na+, and K+ showed remarkably seasonal variation, with the highest value observed in winter, followed by spring and autumn, and the lowest value observed in summer. High VWM concentration of these ions in winter were mainly due to adverse meteorological conditions (e.g., rare rainfall, lower planetary boundary height, and stagnant air) and intensive anthropogenic emissions. SO42-, NO3-, and F- ions peaked in the southeastern Sichuan province, which is a typical industrial region. NH4+ concentrations decreased from 268 µeq L-1 in the east to 10.4 µeq L-1 in the western Sichuan province, which could be related to the development of agriculture in the eastern Sichuan province. Ca2+ peaked in southeastern Sichuan province due to intensive construction activities and severe stone desertification. On the basis of Positive Matrix Factorization (PMF) analysis, four sources of inorganic ions in rainwater were identified, including anthropogenic source, crust, biomass burning, and aging sea salt aerosol. Geographically Weighted Regression (GWR) was used to find the spatial correlations between the socio-economic factors and ions in the rainwater. At the regional scale, the influence of fertilizer consumption and Gross Agricultural Production (GAP) on NH4+ increased from east to west; moreover the influence of Gross Industrial Production (GIP) on SO42- and NO3- also increased.


Assuntos
Chuva Ácida/análise , Aerossóis/química , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Compostos Inorgânicos/análise , Chuva/química , China , Conservação dos Recursos Naturais , Monitoramento Ambiental , Estações do Ano , Água/análise
12.
Environ Pollut ; 254(Pt A): 112864, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31369912

RESUMO

To better understand the mechanism of PM2.5 explosive growth (EG), we conducted concurrent measurements of gaseous pollutants, PM2.5 and its chemical composition (inorganic ions, organic carbon, and element carbon) with a time resolution of 1 h in Shanghai in late autumn and winter from 2014 to 2017. In this study, the EG events, which are defined as the net increase in the mass concentration of PM2.5 by more than 100 µg m-3 within hours, are separately discussed for 3, 6, or 9 h. The number of EG events decreased from 19 cases in 2014 to 6 cases in 2017 and the corresponding PM2.5 concentration on average decreased from 183.6 µg m-3 to 128.8 µg m-3. Both regional transport and stagnant weather (windspeed < 2.0 m s-1) could lead to EG events. The potential source contribution function (PSCF) shows that the major high-pollution region is in East China (including Zhejiang, Jiangsu, Shandong, and Anhui Province) and the North China Plain. The contribution of stagnant conditions to EG episode hours of 55% (198 h, 156.9 µg m-3) is higher than that of regional transport (45%, 230 h, 163.0 µg m-3). To study the impact of local emission, chemical characteristics and driving factors of EG were discussed under stagnant conditions. The major components contributing to PM2.5 are NO3- (17.9%), organics (14.1%), SO42- (13.1%), and NH4+ (13.1%). The driving factors of EG events are the secondary aerosol formation of sulfate and nitrate and primary emissions (vehicle emissions, fireworks, and biomass burning), but the secondary transformation contributes more to EG events. The formation of sulfate and nitrate is dominated by gas-phase oxidation and heterogeneous reactions, which are enhanced by a high relative humidity. The current study helps to understand the chemical mechanism of haze and provides a scientific basis for air pollution control in Shanghai.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Material Particulado/análise , Aerossóis/análise , Carbono/análise , China , Poluentes Ambientais , Poluição Ambiental , Gases , Nitratos/análise , Óxidos de Nitrogênio , Estações do Ano , Sulfatos/análise , Emissões de Veículos/análise , Tempo (Meteorologia)
13.
Sci Total Environ ; 682: 138-150, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31112815

RESUMO

Nitrous acid (HONO) is an important precursor of hydroxyl radical (OH), which plays a key role in atmospheric chemistry. In this study, a shipboard-based measurement of HONO and related species in the offshore area of the East China Sea (ECS) was performed during June 2017. The HONO concentration ranged from 35 ppt to 1.95 ppb, with an average value of 0.44 ±â€¯0.25 ppb during the entire campaign. HONO displayed a relatively higher level (0.48 ±â€¯0.21 ppb) in the area within 30 km from the coastline (S1), whereas a lower level (0.40 ±â€¯0.18 ppb) in the area between 30 km and 100 km from the coastline (S2). Five distinct hotspots of HONO were identified, including Ningbo Port, Yangshan Port, the Yangtze River estuary, northwest of the Zhoushan city, and the area adjacent to Jinshan Chemical Industry Park, suggesting the impact of local vessel emissions and land industrial emissions on HONO formation. During the nighttime, the direct vessel emissions contributed on average 18% of the HONO concentration. The averaged conversion frequency of NO2-to-HONO (khet) estimated from six nighttime cases was 1.18 × 10-2 h-1. Daytime budget analysis showed that the unknown HONO production rate (Punknown) in S1 and S2 was 1.52 ppb h-1 and 1.14 ppb h-1, respectively. Punknown was related to a light-induced HONO source from NO2 on the sea surface and particulate nitrate. During the cruise campaign, the averaged daytime OH production rate from HONO photolysis was 1.35 ±â€¯0.69 ppb h-1, about 1.6 times higher than that from the O3 photolysis (0.87 ±â€¯0.55 ppb h-1), which suggested an important role of HONO in the atmospheric chemistry of the offshore area of ECS.

14.
Biomed Opt Express ; 10(3): 1184-1195, 2019 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30891338

RESUMO

Because of its similar genetic makeup with humans, zebrafish are an available and well-established osteoporosis model in vivo for anti-osteoporosis drug development as well as the drug safety-evaluation process. However, few optical imaging methods could effectively visualize the bone of adult zebrafish due to their limited penetration depth. In this paper, in vivo high-resolution and long-term characterization of a prednisolone-induced osteoporotic zebrafish model was achieved with spectral-domain optical coherence tomography (SD-OCT). The capability of three-dimensional SD-OCT imaging was also demonstrated in this study. With SD-OCT images, we could non-destructively monitor the deforming process of adult zebrafish skull from several directions at any time. There is good correlation and agreement between SD-OCT and histology. Valuable phenomenon such as bone defects could be quantitatively evaluated using the SD-OCT images at different time points during a period of 21 days.

15.
Sci Total Environ ; 649: 1393-1402, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30308908

RESUMO

Adsorbed nitrate is ubiquitous in the atmosphere, and it can undergo photolysis to produce oxidizing active radicals. Nitrate photolysis may be coupled with the oxidation conversions of atmospheric gaseous pollutants. However, the processes involved remain poorly understood. In this study, the impact of adsorbed nitrate on the heterogeneous oxidation of SO2 on α-Fe2O3 was investigated in the absence and presence of simulated solar irradiation by using in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The results indicate that for α-Fe2O3 particles with no adsorbed nitrate, the formation of adsorbed sulfate on humid particles is stronger than that on dry particles. Meanwhile, light can also promote the heterogeneous conversion of SO2 and the formation of sulfate on dry particles because α-Fe2O3 is a typical photocatalyst. However, the heterogeneous conversion of SO2 on humid α-Fe2O3 particles is somewhat suppressed under light, suggesting the occurrence of photoinduced reductive dissolution. For the heterogeneous conversion of SO2 on α-Fe2O3 particles with adsorbed nitrate, the formation of sulfate on humid particles is still higher than that on dry particles. For the dry α-Fe2O3 particles with adsorbed nitrate, light promotes the formation of adsorbed sulfate. For the humid α-Fe2O3 particles with adsorbed nitrate, the heterogeneous conversion of SO2 under light is stronger than that under no light, indicating that the photolysis of adsorbed nitrate is coupled with the oxidation of SO2 and the formation of sulfate. The consumption of adsorbed nitrate and the formation of adsorbed N2O4 are observed during the introduction of SO2. A possible mechanism for the impact of adsorbed nitrate on the heterogeneous conversion of SO2 on α-Fe2O3 particles is proposed, and atmospheric implications based on these results are discussed.

16.
Sci Total Environ ; 648: 902-915, 2019 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-30144758

RESUMO

With rapid economic development and urbanization, China has suffered from severe and persistent air pollution during the past years. In the work, the hourly data of PM2.5, PM10, SO2, NO2, CO, and O3 in all of the prefecture-level cities (336 cities) during 2015-2016 were collected to uncover the spatiotemporal variations and influential factors of these pollutants in China. The average concentrations of PM2.5, PM10, SO2, NO2, and CO decreased by 19.32%, 15.34%, 29.30%, 9.39%, and 8.00% from 2015 to 2016, suggesting the effects of efficient control measurements during this period. On the contrary, the O3 concentration increased by 4.20% during the same period, which mainly owed to high volatile organic compounds (VOCs) loading. The concentrations of PM2.5, PM10, SO2, CO and NO2 showed the highest and the lowest ones in winter and summer, respectively. However, the O3 concentration peaked in summer, followed by ones in spring and autumn, and presented the lowest one in winter. All of the pollutants exhibited significantly weekly and diurnal cycle in China. PM2.5, PM10, SO2, CO and NO2 presented the higher concentrations on weekdays than those at weekends, all of which showed the bimodal pattern with two peaks at late night (21:00-22:00) and in morning (9:00-10:00), respectively. However, the O3 concentration exhibited the highest value around 15:00. The statistical analysis suggested that the PM2.5, PM10, and SO2 concentrations were significantly associated with precipitation (Prec), atmosphere temperature (T), and wind speed (WS). The CO and NO2 concentrations displayed the significant relationship with T, while the O3 concentration was closely linked to the sunshine duration (Tsun) and relative humidity (RH). T and WS were major factors affecting the accumulation of PM and gaseous pollutants at a national scale. At a spatial scale, Prec and T played the important roles on the PM distribution in Northeast China, and the effect of Prec on CO concentration decreased from Southeast China to Northwest China. The results shown herein provide a scientific insight into the meteorology impacts on air pollution over China.

17.
IEEE Trans Vis Comput Graph ; 25(10): 2927-2939, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30059308

RESUMO

We present a novel 3D model-guided interface for in-situ sketching on 3D planes. Our work is motivated by evolutionary design, where existing 3D objects form the basis for conceptual re-design or further design exploration. We contribute a novel workflow that exploits the geometry of an underlying 3D model to infer 3D planes on which 2D strokes drawn that are on and around the 3D model should be meaningfully projected. This provides users with the nearly modeless fluidity of a sketching interface, and is particularly useful for 3D sketching over planes that are not easily accessible or do not preexist. We also provide an additional set of tools, including sketching with explicit plane selection and model-aware canvas manipulation. Our system is evaluated with a user study, showing that our technique is easy to learn and effective for rapid sketching of product design variations around existing 3D models.

18.
IEEE Trans Vis Comput Graph ; 25(3): 1591-1602, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29993604

RESUMO

In recent years, consumer-level depth cameras have been adopted for various applications. However, they often produce depth maps at only a moderately high frame rate (approximately 30 frames per second), preventing them from being used for applications such as digitizing human performance involving fast motion. On the other hand, low-cost, high-frame-rate video cameras are available. This motivates us to develop a hybrid camera that consists of a high-frame-rate video camera and a low-frame-rate depth camera and to allow temporal interpolation of depth maps with the help of auxiliary color images. To achieve this, we develop a novel algorithm that reconstructs intermediate depth maps and estimates scene flow simultaneously. We test our algorithm on various examples involving fast, non-rigid motions of single or multiple objects. Our experiments show that our scene flow estimation method is more precise than a tracking-based method and the state-of-the-art techniques.

19.
IEEE Comput Graph Appl ; 39(2): 38-51, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30530356

RESUMO

We present a simple and efficient method based on deep learning to automatically decompose sketched objects into semantically valid parts. We train a deep neural network to transfer existing segmentations and labelings from three-dimensional (3-D) models to freehand sketches without requiring numerous well-annotated sketches as training data. The network takes the binary image of a sketched object as input and produces a corresponding segmentation map with per-pixel labelings as output. A subsequent postprocess procedure with multilabel graph cuts further refines the segmentation and labeling result. We validate our proposed method on two sketch datasets. Experiments show that our method outperforms the state-of-the-art method in terms of segmentation and labeling accuracy and is significantly faster, enabling further integration in interactive drawing systems. We demonstrate the efficiency of our method in a sketch-based modeling application that automatically transforms input sketches into 3-D models by part assembly.

20.
Environ Sci Technol ; 52(21): 12943-12951, 2018 11 06.
Artigo em Inglês | MEDLINE | ID: mdl-30346144

RESUMO

Container ships have been widely recognized as an important emission source within maritime transport. Heavy fuel oil (HFO) and diesel oil (DO) are the two most commonly used fuels. This study reports the characteristics and toxicities of particulate matter (PM) emissions from HFO and DO combustion in a typical container ship. The PM number size distribution possesses a bimodal structure with peaks at ∼20 nm and ∼100 nm. The PM2.5 emission factors (EFs) are 3.15 ± 0.39 and 0.92 ± 0.02 g/kg fuel for HFO and DO, respectively. The benzo[a]pyrene equivalent carcinogenic potency (BaPeq) of 16 polycyclic aromatic hydrocarbons contained in HFO and DO PM2.5 is approximately 0.81 ± 0.10 and 0.12 ± 0.04 mg/kg fuel, respectively. BaPeq concentration shows an increasing tendency with decreased PM size. The reactive oxygen species activity and cytotoxicity of HFO PM2.5 samples are ∼2.1 and ∼2.5 times higher than those of DO PM2.5 samples, respectively. These health risks are both significantly attributed to the BaPeq content in PM2.5 with correlations of 0.86-0.92. Furthermore, the examined biological effects are much greater than those of atmospheric PM2.5 collected in Shanghai. Our results imply that better fuel quality is important for improving air quality and reducing health risks.


Assuntos
Poluentes Atmosféricos , Hidrocarbonetos Policíclicos Aromáticos , China , Material Particulado , Navios , Emissões de Veículos
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