Showing papers by "Nanjing University of Information Science and Technology published in 2010"
TL;DR: In this article, a receptor model (PMF; positive matrix factorization) coupled with the information related to VOC sources (the distribution of major industrial complex, meteorological conditions, etc.) is applied to identify the major VOC source in Shanghai.
308 citations
TL;DR: In this article, exposure of nanoparticles to organic vapours shows that various organic species can enhance the growth of the nanoparticles, which is a key component of atmospheric aerosols, growing rapidly under ambient conditions.
Abstract: Nanoparticles are a key component of atmospheric aerosols, growing rapidly under ambient conditions. Exposure of nanoparticles to organic vapours shows that various organic species can enhance the growth of nanoparticles.
271 citations
TL;DR: Based on two observational data sets in China from 1956 to 2004, wind speed changes are analyzed. as discussed by the authors showed that the annual mean wind speed (MWS), days of strong wind (SWDs), and maximum wind (MW) all show declining trends over broad areas of China.
Abstract: Based on two observational data sets in China from 1956 to 2004, wind speed changes are analyzed. The annual mean wind speed (MWS), days of strong wind (SWDs), and maximum wind (MW) all show declining trends over broad areas of China. Only in the southeastern Tibetan Plateau and the regions from the Great Bend of the Yellow River southward to Yunnan and Guangxi Provinces wind speeds are not significantly reduced, but rather, in partial, these regions’ winds speeds are slightly increased. The regions with declining trends match the areas with relatively strong observed winds and the regions without significant declining trends match the areas with light observed winds. In the meantime, the regions with relatively strong winds correspond to areas of reduced days of SWDs. Trends for both increasing intensities and for the number of days of light winds both impact the installation of wind energy facilities. These may be advantageous to the development of wind energy in different regions. Urbanization, the change of anemometers, or relocation of stations are factors that are mildly responsible for the decreasing trend of MWS. The main reason for the decreasing trend is that under the background of global warming, the contrasts of the sea level pressure, and near-surface temperature between the Asian continent and the Pacific Ocean have become significantly smaller, and the east Asian trough has shifted eastward and northward, and has weakened as well. Both East Asian winter and summer monsoons are decreasing, and all of these impacts have resulted in declines of MWS in China.
254 citations
TL;DR: The Haar wavelet operational matrix is derived and used to solve the fractional order differential equations including the Bagley-Torvik, Ricatti and composite fractional oscillation equations.
250 citations
TL;DR: Chebyshev wavelet operational matrix of the fractional integration is derived and used to solve a nonlinear fractional differential equations as mentioned in this paper, and some examples are included to demonstrate the validity and applicability of the technique.
245 citations
TL;DR: The authors investigates the responses of the EASM from observations, theoretical, and modeling perspectives, showing that the regional-mean rainfall is basically dominated by considerable interannual-to-decadal fluctuations, concurrent with enhanced precipitation over the middle and lower reaches of the Yangtze River and over southern Japan and suppressed rainfall amount over the South China and Philippine Seas.
Abstract: The Indian summer monsoon (ISM) tends to be intensified in a global-warming scenario, with a weakened linkage with El Nino–Southern Oscillation (ENSO), but how the East Asian summer monsoon (EASM) responds is still an open question. This study investigates the responses of the EASM from observations, theoretical, and modeling perspectives. Observational and theoretical evidence demonstrates that, in contrast to the dramatic global-warming trend within the past 50 years, the regional-mean EASM rainfall is basically dominated by considerable interannual-to-decadal fluctuations, concurrent with enhanced precipitation over the middle and lower reaches of the Yangtze River and over southern Japan and suppressed rainfall amount over the South China and Philippine Seas. From 1958 through 2008, the EASM circulation exhibits a southward shift in its major components (the subtropical westerly jet stream, the western Pacific Ocean subtropical high, the subtropical mei-yu–baiu–changma front, and the tropical...
210 citations
Book•
07 Sep 2010
TL;DR: This chapter presents some fundamental definitions related to UAVs and MAVs for clarification, and discusses the contents of this monograph.
Abstract: This chapter contains a non-technical and general discussion about unmanned aerial vehicles (UAVs) and micro aerial vehicles (MAVs). This chapter presents some fundamental definitions related to UAVs and MAVs for clarification, and discusses the contents of this monograph. The goal of this chapter is to help the reader to become familiar with the contents of the monograph and understand what to expect from each chapter.
205 citations
TL;DR: In this article, the impacts of organic cropping system on global warming potentials were evaluated in conventional and organic rice (Oryza sativa L.) cropping systems in southeast China.
Abstract: To evaluate the impacts of organic cropping system on global warming potentials (GWPs), field measurements of CH4 and N2O were taken in conventional and organic rice (Oryza sativa L.) cropping systems in southeast China. Rice paddies were under various water regimes, including continuous flooding (F), flooding–midseason drainage–reflooding (F-D-F), and flooding–midseason drainage–reflooding and moisture but without waterlogging (F-D-F-M). Nitrogen was applied at the rate of 100 kg N ha−1, as urea-N or pelletized, dehydrated manure product in conventional or organic rice paddies, respectively. Seasonal fluxes of CH4 averaged 4.44, 2.14, and 1.75 mg m−2 h−1 for the organic paddy plots under the water regimes of F, F-D-F and F-D-F-M, respectively. Relative to conventional rice paddies, organic cropping systems increased seasonal CH4 emissions by 20%, 23%, and 35% for the plots under the water regimes of F, F-D-F, and F-D-F-M, respectively. Under the water regimes of F-D-F and F-D-F-M, seasonal N2O-N emissions averaged 10.85 and 13.66 μg m−2 h−1 in organic rice paddies, respectively, which were significantly lower than those in conventional rice paddies. The net global warming potentials (GWPs) of CH4 and N2O emissions from organic rice paddies relative to conventional rice paddies were significantly higher or comparable under various water regimes. The greenhouse gas intensities were greater, while carbon efficiency ratios were lower in organic relative to conventional rice paddies. The results of this study suggest that organic cropping system might not be an effective option for mitigating the combined climatic impacts from CH4 and N2O in paddy rice production.
173 citations
TL;DR: In this article, the authors show that the frequency of fog events in wintertime over eastern-central China has doubled over the past three decades and the mean number of cold air outbreaks has decreased from 7 to around 5 times per winter; relative humidity and the frequency for light wind events have also increased significantly.
Abstract: [1] Fog is a severe weather hazard that greatly influences traffic and daily life with potentially heavy economic loss. An increasing number of traffic accidents caused by fog have been reported in China in recent years. In this study, we show that the frequencies of fog events in wintertime over eastern-central China have doubled over the past three decades. For the same period, surface wind speeds have dropped from 3.7 m/s to about 3 m/s and the mean number of cold air outbreaks has decreased from 7 to around 5 times per winter; relative humidity and the frequency of light wind events have also increased significantly. Weakening of the East Asian winter monsoon system appears to be responsible for these changes. The weakened East Asian winter monsoon circulation brings less cold and dry air to the region, reduces wind speed, and favors the formation of fog. The regional increase in atmospheric aerosol loading may also change the regional circulation pattern, creating favorable conditions for fog. This hypothesis is tested using the National Centers for Environmental Prediction (NCEP) reanalysis data and model simulations with the National Center for Atmospheric Research Community Climate Model (NCAR/CCM3). The analyses show that the 500hPa trough in East Asia has shallowed over the past three decades. Meanwhile, the surface Siberian high has weakened which is likely the cause for the diminishment in speed of the prevailing northwesterly winds and the reduction in intrusions of dry and cold air from the northwest. The increase in atmospheric aerosols was shown to heat the atmosphere and generates a cyclonic circulation anomaly over eastern-central China. This circulation anomaly also leads to a reduction in the influx of dry and cold air over eastern-central China. These effects are responsible for the increased convergence of water vapor therein. All these changes favor the formation and maintenance of fog over this region.
164 citations
TL;DR: In this article, Fe-doped ZnO thin films were prepared by sol-gel method on Si and glass substrates and influence of Fe doping concentration on the structural and optical properties of the films was studied.
150 citations
TL;DR: The results showed an increase in the frequency of accidents from 2000 to 2007 and a decline in 2008, indicating the need to improve certain safety measures in the road transport of hazmat in China.
TL;DR: In this article, the effect of aging time of ZnO sol on the structural and optical properties of the films was studied and it was shown that appropriate aging of the sol is very important for the improvement of structural and the optical quality of the thin films derived from sol-gel method.
TL;DR: A field experiment in a rice-winter wheat rotation system was conducted to gain an insight into the water regime-specific emission factors and background emissions of nitrous oxide (N(2)O) over the whole annual cycle.
TL;DR: In this paper, Li et al. measured aerosol optical thickness at 25 stations distributed across China and found that aerosols have very little impact on the atmosphere-surface system but substantially warm up the atmosphere at the expense of cooling the surface.
Abstract: [1] Heavy loading of aerosols in China is widely known, but little is known about their impact on regional radiation budgets, which is often expressed as aerosol radiative forcing (ARF). Cloud-free direct ARF has either been estimated by models across the region or determined at a handful of locations with aerosol and/or radiation measurements. In this study, ARF is determined at 25 stations distributed across China where aerosol optical thickness has been measured since 2004. In combination with the single-scattering albedo retrieved from ground and satellite measurements, ARF was determined at all the stations at the surface, inside the atmosphere, and at the top of atmosphere (TOA). Nationwide annual and diurnal mean ARF is found to be −15.7 ± 8.9 at the surface, 0.3 ± 1.6 at the TOA, and 16.0 ± 9.2 W m−2 inside the atmosphere. These values imply that aerosols have very little impact on the atmosphere-surface system but substantially warm up the atmosphere at the expense of cooling the surface. The strong atmospheric absorption is likely to alter atmospheric thermodynamic conditions and thus affects circulation considerably.
TL;DR: In this paper, the authors investigated differences of track, intensity, frequency, and associated long-term trends for those TCs that were simultaneously recorded by the best track data sets of the Joint Typhoon Warning Center (JTWC), the Regional Specialized Meteorological Center (RSMC) Tokyo, and the Shanghai Typhoon Institute (STI).
Abstract: [1] The hot debate over the influence of global warming on tropical cyclone (TC) activity in the western North Pacific over the past several decades is partly due to the diversity of TC data sets used in recent publications. This study investigates differences of track, intensity, frequency, and the associated long-term trends for those TCs that were simultaneously recorded by the best track data sets of the Joint Typhoon Warning Center (JTWC), the Regional Specialized Meteorological Center (RSMC) Tokyo, and the Shanghai Typhoon Institute (STI). Though the differences in TC tracks among these data sets are negligibly small, the JTWC data set tends to classify TCs of category 2-3 as category 4-5, leading to an upward trend in the annual frequency of category 4-5 TCs and the annual accumulated power dissipation index, as reported by Webster et al. (2005) and Emanuel (2005). This trend and potential destructiveness over the period 1977-2007 are found only with the JTWC data set, but downward trends are apparent in the RSMC and STI data sets. It is concluded that the different algorithms used in determining TC intensity may cause the trend discrepancies of TC activity in the western North Pacific.
TL;DR: In this paper, the authors reported the first aircraft measurements of atmospheric trace gases, aerosols, and clouds over this part of China, a region strongly affected by both natural desert dust and pollution smog.
Abstract: [1] North China (Huabei in Chinese) is a geographical region located between 32°N and 42°N latitude in eastern China, including several provinces and large municipalities (e.g., Beijing and Tianjin). In the past decades the region has experienced dramatic changes in air quality and climate. Among the multiple causes aerosol pollution is expected to play a particularly important role. To investigate this, a field measurement campaign was performed in April–May 2006 as part of the project Influence of Pollution on Aerosols and Cloud Microphysics in North China. Here we report the first aircraft measurements of atmospheric trace gases, aerosols, and clouds over this part of China, a region strongly affected by both natural desert dust and pollution smog. We observed very high concentrations of gaseous air pollutants and haze particles, partly together with nonprecipitating stratiform clouds. The clouds were characterized by numerous droplets, much smaller than in a less-polluted atmosphere. Our data reveal that the highly efficient coating of dust particles by pollution acids provides the predominant source of cloud condensation nuclei. The pollution-enhanced activation of dust particles into droplets is shown to be remarkably efficient so that clouds even form below 100% relative humidity. Contrary to previous analyses, we find that the haze particles influence the spectral shape of the cloud droplet size distribution such that the indirect climate cooling effect of aerosols on clouds is increased. The widespread haze, combined with low clouds, diminishes air quality and exerts an unusually strong cooling forcing on climate.
TL;DR: In this article, the joint size and fall velocity distributions of raindrops were measured with a Particle Size and Velocity (PARSIVEL) precipitation particle disdrometer in a field experiment conducted during July and August 2007 at a semiarid continental site located in Guyuan, Ningxia Province, China (36°N, 106°16′E).
Abstract: Joint size and fall velocity distributions of raindrops were measured with a Particle Size and Velocity (PARSIVEL) precipitation particle disdrometer in a field experiment conducted during July and August 2007 at a semiarid continental site located in Guyuan, Ningxia Province, China (36°N, 106°16′E). Data from both stratiform and convective clouds are analyzed. Comparison of the observed raindrop size distributions shows that the increase of convective rain rates arises from the increases of both drop concentration and drop diameter while the increase of the rain rate in the stratiform clouds is mainly due to the increase of median and large drop concentration. Another striking contrast between the stratiform and convective rains is that the size distributions from the stratiform (convective) rains tend to narrow (broaden) with increasing rain rates. Statistical analysis of the distribution pattern shows that the observed size distributions from both rain types can be well described by the gamma ...
TL;DR: In this paper, a review of fog field experiments and their major results relating to fog mechanisms, physical properties and chemical characteristics is presented, and the effects of urbanization and industrialization on fog are highlighted.
Abstract: Fog can adversely affect human activity directly and indirectly, resulting in large losses both in terms of the local economy and lives. Much effort has been devoted to studies of fog across many areas of China, and in that context this paper aims to summarize climatic characteristics and review fog field experiments and their major results relating to fog mechanisms, physical properties and chemical characteristics. Progress in the application of remote sensing techniques and numerical simulation in fog research are also discussed. In particular, the effects of urbanization and industrialization on fog are highlighted. To end, perspectives on future fog research are outlined. The goal of this review paper is to introduce fog research in China to the global academic community and thus promote international collaboration on fog research. This is important because most papers on fog in China are published in Chinese, which are unreadable for the vast majority of non-Chinese researchers.
TL;DR: In this paper, a method that automatically corrects for large errors due to bright band effects in a real-time national radar quantitative precipitation estimation (QPE) product was developed.
Abstract: The bright band (BB) is a layer of enhanced reflectivity due to melting of aggregated snow and ice crystals. The locally high reflectivity causes significant overestimation in radar precipitation estimates if an appropriate correction is not applied. The main objective of the current study is to develop a method that automatically corrects for large errors due to BB effects in a real-time national radar quantitative precipitation estimation (QPE) product. An approach that combines the mean apparent vertical profile of reflectivity (VPR) computed from a volume scan of radar reflectivity observations and an idealized linear VPR model was used for computational efficiency. The methodology was tested for eight events from different regions and seasons in the United States. The VPR correction was found to be effective and robust in reducing overestimation errors in radar-derived QPE, and the corrected radar precipitation fields showed physically continuous distributions. The correction worked consiste...
TL;DR: A modified SO(3) procedure to maximize the elimination of measurement biases, based on the inertial-filter-sampling and the selective-condensation-collecting ofSO(3), was applied in SO( 3) tests in three full-scale utility boilers, and tests in a lab-scale reactor confirmed there are major interferences between fly ash and SO(1) sampling.
Abstract: The formation of sulfur trioxide (SO(3)) in coal-fired utility boilers can have negative effects on boiler performance and operation, such as fouling and corrosion of equipment, efficiency loss in the air preheater (APH), increase in stack opacity, and the formation of PM(2.5). Sulfur trioxide can also compete with mercury when bonding with injected activated carbons. Tests in a lab-scale reactor confirmed there are major interferences between fly ash and SO(3) during SO(3) sampling. A modified SO(3) procedure to maximize the elimination of measurement biases, based on the inertial-filter-sampling and the selective-condensation-collecting of SO(3), was applied in SO(3) tests in three full-scale utility boilers. For the two units burning bituminous coal, SO(3) levels starting at 20 to 25 ppmv at the inlet to the selective catalytic reduction (SCR), increased slightly across the SCR, owing to catalytic conversion of SO(2) to SO(3,) and then declined in other air pollutant control device (APCD) modules downstream to approximately 5 ppmv and 15 ppmv at the two sites, respectively. In the unit burning sub-bituminous coal, the much lower initial concentration of SO(3) estimated to be approximately 1.5 ppmv at the inlet to the SCR was reduced to about 0.8 ppmv across the SCR and to about 0.3 ppmv at the exit of the wet flue gas desulfurization (WFGD). The SO(3) removal efficiency across the WFGD scrubbers at the three sites was generally 35% or less. Reductions in SO(3) across either the APH or the dry electrostatic precipitator (ESP) in units burning high-sulfur bituminous coal were attributed to operating temperatures being below the dew point of SO(3).
TL;DR: The efficiency of the multi-agent technology for WSN based the SHM applications on the large aircraft structures is shown and implementation in the validation work for two typical kinds of structure states are presented.
Abstract: Much attention has been focused on the research of structural health monitoring (SHM), since it could increase the safety and reduce the maintenance costs of engineering structures. In recent years, wireless sensor network (WSN) has been explored for adoption to improve the centralized cable-based SHM system performances. This paper presents a multi-agent design method and system evaluation for wireless sensor network based structural health monitoring to validate the efficiency of the multi-agent technology. Through the cooperation of six different agents for SHM applications, the distributed wireless sensor network can automatically allocate SHM tasks, self-organize the sensor network and aggregate different sensor information. In the evaluation work, the strain gauge and PZT sensors are used to monitor strain distribution change and joint failure of an experimental aluminum plate structure. A dedicated sensor network platform including the wireless strain node, wireless PZT node and wireless USB station is designed for the evaluation system. Based on the hardware platform, the multi-agents software architecture is defined. The multi-agent monitoring principle and implementation in the validation work for two typical kinds of structure states are presented. This paper shows the efficiency of the multi-agent technology for WSN based the SHM applications on the large aircraft structures.
TL;DR: In this article, N-doped TiO2 nanotube arrays (NTN) were prepared by anodization and dip-calcination method, and the surface morphology of samples was characterized by SEM.
TL;DR: In this paper, the authors developed a model describing the dependence of annual soil respiration on climate and soil properties, which was able to explain 41%, 57%, and 31% of the variability of soil respiology for croplands, grasslands, forests, and tundra ecosystems.
TL;DR: The HR-TEM and SAED patterns indicated that the synthesized selenium nanoparticles were amorphous, and Shewanella sp.
Abstract: Shewanella sp. HN-41 was exploited for selenium nanoparticles synthesis from aqueous selenite compounds under anaerobic conditions. Various reaction conditions, including reaction time, initial biomass, and initial selenite concentration, were systematically investigated to determine their effects on particle size distribution and formation rate. The biomass concentration of Shewanella sp. HN-41 had no significant effect on average particle size but strongly influenced reduction rate and size distribution. Initial selenite concentration (0.01–1.0 mM) also had no significant effect on the average particle size, but affected the early growth stage mechanism of selenium particle production, which was modeled using a Michaelis Menten model. The HR-TEM and SAED patterns indicated that the synthesized selenium nanoparticles were amorphous.
TL;DR: Oxidized N (NO(3)(-) in the precipitation and gaseous NO(2)) was the dominant form of nitrogen deposition in the studied region, indicating that reactive forms of nitrogen created from urban areas contribute greatly to N deposition inThe rural area evaluated in this study.
TL;DR: In this paper, the influence of the El Nino-Southern Oscillation (ENSO) on the peak-season (July-September) TC prevailing tracks in the western North Pacific basin was assessed based on 14 selected El NINO and 14 selected La Nina years during the period 1950-2007.
Abstract: Using a statistical model for simulating tropical cyclone (TC) formation and a trajectory model for simulating TC tracks, the influence of the El Nino-Southern Oscillation (ENSO) on the peak-season (July–September) TC prevailing tracks in the western North Pacific basin is assessed based on 14 selected El Nino and 14 selected La Nina years during the period 1950–2007.
TL;DR: In this paper, the authors present two robust three-party quantum secret sharing protocols against two kinds of collective noise, where each logical qubit is made up of two physical qubits and is invariant under a collective noise.
TL;DR: In this article, X-ray diffraction and scanning electron microscope (SEM) imaging of aerosol samples acquired at a rural site in northern China from March to August 2005 was used to compare coal fly ash and the atmospheric aerosols suggests that direct emission from coal combustion is a substantial source of primary atmospheric sulfate.
Abstract: abundances ( 32 S, 33 S, 34 S, and 36 S) and by detailed X‐ray diffraction and scanning electron microscope (SEM) imaging of aerosol samples acquired at a rural site in northern China from March to August 2005. The comparison of SEM images from coal fly ash and the atmospheric aerosols suggests that direct emission from coal combustion is a substantial source of primary atmospheric sulfate in the form of CaSO4. Airborne gypsum (CaSO4·2H2O) is usually attributed to eolian dust or atmospheric reactions with H2SO4. SEM imaging also reveals mineral particles with soot aggregates adhered to the surface where they could decrease the single scattering albedo of these aerosols. In summer months, heterogeneous oxidation of SO2, derived from coal combustion, appears to be the dominant source of atmospheric sulfate. Our analyses of aerosol sulfate show a seasonal variation in D 33 S( D 33 S describes either a 33 S excess or depletion relative to that predicted from consideration of classical mass‐dependent isotope effects). Similar sulfur isotope variationshavebeenobservedinotheratmosphericsamplesandin(homogenous)gas‐phase reactions. On the basis of atmospheric sounding and satellite data as well as a possible relationship between D 33 S and Convective Available Potential Energy (CAPE) during the sampling period, we attribute the sulfur isotope anomalies (D 33 S and D 36 S) in Xianghe aerosol sulfates to another atmospheric source (upper troposphere or lower stratosphere).
TL;DR: In this paper, the authors investigated the long-term variability in sea surface temperature (SST) in the equatorial Pacific and its relationship with global warming using three SST data sets (Hadley Center Global Sea Ice and Sea Surface Temperature, extended reconstruction SEI and Kaplan), atmospheric fields from National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis, and subsurface sea temperature from Simple Ocean Data Assimilation data set.
Abstract: [1] Long-term variability in sea surface temperature (SST) in the equatorial Pacific and its relationship with global warming were investigated using three SST data sets (Hadley Center Global Sea Ice and Sea Surface Temperature, extended reconstruction sea surface temperature, and Kaplan), atmospheric fields from National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis, and subsurface sea temperature from the Simple Ocean Data Assimilation data set. A cooling mode in the equatorial Pacific cold tongue is evident in all three SST data sets for two periods: 1870-2007 and 1948-2007. This cooling, which is indicated by the second empirical orthogonal function mode, is characterized by cooling in the Pacific cold tongue and warming elsewhere in the tropical Pacific. Its principal component time series is highly correlated with global mean surface temperature combining air temperature and SST. In association with the SST cooling mode, atmospheric fields and subsurface sea temperature are coupled in the tropical Pacific during recent decades. Moreover, for the coupled models in the 20th century run (20C3M), obtained from the Intergovernmental Panel on Climate Change Fourth Assessment Report database, those with realistic features of El Nino-Southern Oscillation (ENSO) events can well show the cooling mode. However, the cooling mode is not shown in these coupled models in a preindustrial scenario with no forcing attributed to global warming. Results from observations and models suggest that the cooling mode is very likely caused by global warming. This conclusion is supported by a hypothesis that considers dynamic effects in the equatorial Pacific Ocean in response to global warming.
TL;DR: In this paper, the authors considered a quasilinear viscoelastic wave equation in canonical form with the homogeneous Dirichlet boundary condition and showed that the decay rate of the solution energy is similar to that of the relaxation function.
Abstract: In this paper we consider a quasilinear viscoelastic wave equation in canonical form with the homogeneous Dirichlet boundary condition. We prove that, for certain class of relaxation functions and certain initial data in the stable set, the decay rate of the solution energy is similar to that of the relaxation function. This result improves earlier ones obtained by Messaoudi and Tatar [S.A. Messaoudi, N.-E. Tatar, Global existence and uniform stability of solutions for a quasilinear viscoelastic problem, Math. Methods Appl. Sci. 30 (2007) 665–680] in which only the exponential and polynomial decay rates are considered. Conversely, for certain initial data in the unstable set, there are solutions that blow up in finite time. The last result is new, since it allows a larger class of initial energy which may take positive values.