Showing papers by "Nanjing University of Information Science and Technology published in 2008"

Corporate governance and tunneling: Empirical evidence from China

Abstract: We analyze asset appropriation by principal shareholders in China and uncover the following relationships: (1) outsiders in the board of directors, audit without non-clean opinion, and dispersed ownership prevent operational tunneling; (2) belonging to a business group and issuing B or H share exacerbate asset appropriation Institutional ownership does not prevent the embezzlement of assets and is endogenous, as investors select companies with good governance Besides governance mechanisms, stock characteristics matter in that larger firms exhibit less tunneling, whereas highly leveraged firms experience the opposite We find a decline of tunneling in 2001, which might be due to economic reforms

Synthesis of flower-like CuO nanostructures as a sensitive sensor for catalysis

Abstract: The flower-like CuO nanostructures were hydrothermally synthesized without using any template. The influences of hydrothermal temperature and time on the growth of nanostructures were investigated. The samples were characterized by means of scanning electron microscope (SEM), X-ray powder diffraction (XRD), transmission electron microscope (TEM), high-resolution transmission electron microscope (HRTEM), selected area electron diffraction (ED), and N2 adsorption isotherm. Interestingly, these architectures are made of three-order structures. The formation mechanism of the flower-like CuO was proposed and explained. Furthermore, the chemiluminescence (CL) and catalysis properties of the flower-like CuO were also investigated. The flower-like nanostructures showed the high-CL intensities and reactive activities for CO oxidation. The flower-like CuO can be used to fabricate a highly sensitive CL detector. This CL mode is a rapid and effective method for the selection of new catalysts from thousands of materials.

Increase of cloud droplet size with aerosol optical depth: An observation and modeling study

Abstract: [1] Cloud droplet effective radius (DER) is generally negatively correlated with aerosol optical depth (AOD) as a proxy of cloud condensation nuclei. In this study, cases of positive correlation were found over certain portions of the world by analyzing the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite products, together with a general finding that DER may increase or decrease with aerosol loading depending on environmental conditions. The slope of the correlation between DER and AOD is driven primarily by water vapor amount, which explains 70% of the variance in our study. Various potential artifacts that may cause the positive relation are investigated including the effects of aerosol swelling, partially cloudy, atmospheric dynamics, cloud three-dimensional (3-D) and surface influence effects. None seems to be the primary cause for the observed phenomenon, although a certain degree of influence exists for some of the factors. Analyses are conducted over seven regions around the world representing different types of aerosols and clouds. Only two regions show positive dependence of DER on AOD, near coasts of the Gulf of Mexico and South China Sea, which implies physical processes may at work. Using a 2-D Goddard Cumulus Ensemble model (GCE) with spectral-bin microphysics which incorporated a reformulation of the Kohler theory, two possible physical mechanisms are hypothesized. They are related to the effects of slightly soluble organics (SSO) particles and giant cloud condensation nuclei (CCN). Model simulations show a positive correlation between DER and AOD, due to a decrease in activated aerosols with an increasing SSO content. Addition of a few giant CCNs also increases the DER. Further investigations are needed to fully understand and clarify the observed phenomenon.

Synthesis Gas Production with an Adjustable H2/CO Ratio through the Coal Gasification Process: Effects of Coal Ranks And Methane Addition

Abstract: With the decline of oil reserves and production, the gas-to-liquids (GTL) part of Fischer–Tropsch (F-T) synthesis technology has become increasing important. Synthesis gas (H2 + CO) with a stoichiometric ratio (H2/CO) at 2 or ranging from 1 to 2 is generally used in major synthesis-gas-based chemicals production. There are growing interests in the development of an alternative technology, other than the expensive natural-gas-based catalytic process, for cost-effective production of synthesis gas with a flexible hydrogen/carbon monoxide (H2/CO) ratio. Direct production of synthesis gas using coal as a cheap feedstock is attractive but challenging due to its low H2/CO ratio of generated synthesis gas. Three typical U.S. coals of different ranks were tested in a 2.5 in. coal gasifier to investigate their gasification reactivity and adjustability on H2/CO ratio of generated synthesis gas with or without the addition of methane. Tests indicated that lower-rank coals (lignite and sub-bituminous) have higher gas...

Global exponential stability in Lagrange sense for recurrent neural networks with time delays

Abstract: In this paper, we study the global exponential stability in Lagrange sense for continuous recurrent neural networks (RNNs) with multiple time delays. Three different types of activation functions are considered, which include both bounded and unbounded activation functions. By constructing appropriate Lyapunov-like functions, we provide easily verifiable criteria for the boundedness and global exponential attractivity of RNNs. These results can be applied to analyze monostable as well as multistable neural networks.

The physical–chemical characterization of mechanically-treated CFBC fly ash

Abstract: The physical–chemical characteristics of mechanically-treated circulating fluidized bed combustion (CFBC) fly ash, such as 45 μm sieve residue, granulometric distribution, water requirement, specific gravity, pH value, and mineralogical phases, were investigated. It was found that the grinding process can be divided into three stages. The increase in fineness of ground CFBC fly ash is very sharp in the first stage, then slows down in the second stage, and in the last stage it becomes almost invary. The water requirement decreases with prolonged grinding time, and slightly increases during the last stage of grinding. Ground CFBC fly ash shows a higher specific gravity due to the crushing of coarse particles and carbon particles. The pH of ground CFBC fly ash is greater than that of the original CFBC fly ash, indicating that ground samples react more rapidly with water. The mineralogical compositions remain unchanged with grinding, although the intensity of the crystalline phases decreases and the half peak width increases.

Aerosol optical depth over the Tibetan Plateau and its relation to aerosols over the Taklimakan Desert

Abstract: [1] The Multiangle Imaging SpectroRadiometer (MISR) aerosol optical depths (AODs) over the Tibetan Plateau (TP) are compared with ground-based remote sensing data. The result shows that 27 out of 32 MISR AODs fall within the expected uncertainty, i.e., 0.05 or 20% × AOD. The mean bias and the root mean square error between ground and satellite AODs are 0.01 and 0.03, respectively. The 7-year MISR AOD data are used to study seasonal and inter-annual variations of AOD over the TP. The results show distinct seasonal variation, with seasonal AOD being 0.27, 0.25, 0.13 and 0.11 from spring to winter. AOD over the TP is closely related to that over the Taklimakan desert in summer; however poor correlation is observed in spring. Higher AOD in spring and summer over the TP merits further study, including its causes and implications for climate and environment.

An Observational Study of Environmental Dynamical Control of Tropical Cyclone Intensity in the Atlantic

Abstract: An attempt has been made to extend the analysis of environmental dynamical control of tropical cyclone (TC) intensity recently performed for the western North Pacific to the North Atlantic. The results show that both the vertical shear and translational speed have negative effects on TC intensity, which is consistent with previous findings for other basins. It shows that few TCs intensified when they moved faster than 15 m s 1 . The threshold vertical shear of 20 m s 1 —defined as the difference of total winds between 200 and 850 hPa averaged within 5° latitude around the TC center—is found above which few TCs intensified and below which most TCs could reach their lifetime peak intensity. The average intensity of total TCs in the Atlantic is a bit smaller than that in the western North Pacific. The SST-determined empirical maximum potential intensity (EMPI) for a TC for 1981–2003 in this study is slightly higher than that found for 1962–92 by DeMaria and Kaplan in the Atlantic, however. To be consistent with the theoretical TC MPI, a new EMPI has been constructed, which includes the effect of thermodynamic efficiency. This new EMPI marginally improves the estimation of real TC maximum intensity because the thermodynamic efficiency is largely determined by SST. To include the environmental dynamical control of TC intensity, a dynamical efficiency has been introduced, which is inversely proportional to the combined amplitude of the vertical shear and translational speed. With this dynamical efficiency, an empirical maximum intensity (EMI) for Atlantic TCs has been constructed. This EMI includes not only the positive contribution by SST but also the effects of both thermodynamic and dynamical efficiencies, and it provides more accurate estimations of TC maximum intensity. Furthermore, the formulation of the new EMI explains the observed behavior of TC maximum intensity by thermodynamic and dynamical controls in a transparent and easy-to-interpret manner.

Rice Mapping and Monitoring Using ENVISAT ASAR Data

Abstract: Radar remote sensing technology has become an important method for stable and long-time rice monitoring for its capability to operate in all weather conditions. In this letter, ENVISAT advanced synthetic aperture radar (ASAR) alternative-polarization VV/HH data were used for rice monitoring in the Xinghua rice experiment site in the middle of Jiangsu Province. First, a threshold classification method was developed for mapping rice growth area according to the different characteristic of backscatter coefficients between paddy rice and other land surface objects. Then, relational models were built for retrieving rice growth parameters from ASAR images based on correlation analysis between backscatter coefficients and field measurements. Meanwhile, an optical multispectral image was used as ancillary data for rice parameters retrieval. As expected, the retrieved rice growth parameters were consistent with those of field measurements.

CH4 emission with differences in atmospheric CO2 enrichment and rice cultivars in a Japanese paddy soil

Abstract: A pot experiment was conducted to investigate CH4 emissions from a sandy paddy soil as influenced by rice cultivars and atmospheric CO2 elevation. The experiment with two CO2 levels, 370 μL L−1 (ambient) and 570 μL L−1 (elevated), was performed in a climatron, located at the National Institute for Agro-Environmental Sciences, Tsukuba, Japan. Four rice cultivars were tested in this experiment, including IR65598, IR72, Dular and Koshihikari. Tiller number, root length and grain yield were clearly larger under elevated CO2 than under ambient CO2. IR72 and Dular showed significantly higher tiller number, root length and grain yield than Koshihikari and IR65598. Average daily CH4 fluxes under elevated CO2 were significantly larger by 10.9–23.8% than those under ambient CO2, and varied with the cultivars in the sequence Dular ≧ IR72>IR65598 ≧ Koshihikari. Dissolved organic C (DOC) content in the soil was obviously higher under elevated CO2 than under ambient CO2 and differed among the cultivars, in the sequence IR72>Dular>Koshihikari>IR65598. The differences in average daily CH4 fluxes between CO2 levels and among the cultivars were related to different root exudation as DOC content, root length and tiller number. This study indicated that Koshihikari should be a potential cultivar for mitigating CH4 emission and simultaneously keeping stable grain yield, because this cultivar emitted lowest CH4 emission and produced medium grain yield.

Blow-up of the Solution for a p-Laplacian Equation with Positive Initial Energy

Abstract: In this paper we consider a p-Laplacian equation with the homogeneous Dirichlet boundary condition. We establish a blow-up result for certain solution with positive initial energy.

Features of the EAP events on the medium-range evolution process and the mid- and high-latitude Rossby wave activities during the Meiyu period

Abstract: In this paper, features for the evolution of the East Asia/Pacific (EAP) events and their association with high-and mid-latitude Rossby waves during the Meiyu period are analyzed on the medium-range time scale. It is shown that life cycles of the positive and negative EAP events cannot be simply regarded as “mirror” each other. In the upper troposphere, downward propagations of Rossby wave packets both over high-and mid-latitude regions of Eurasian continent and over the Asian jet region are responsible for generating basic patterns of high-and mid-latitude anomaly centers of the events. In this layer, Rossby wave packets also propagate from the mid-latitude anomaly center to the high-latitude one. In the middle and lower troposphere, the formation of the subtropical anomaly center of the event is mainly attributed to the anomalous convective activity in the tropical Pacific warm pool. The northward Rossby wave energy dispersion from this center is favorable to the enhancement and maintenance of the mid-latitude anomaly center in the same layer. Finally, it might be hypothesized that typical features of the positive and negative EAP events in their mature phase result from the interaction between (or phase-locking of) respective anomalous circulations induced both by quasi-zonal Rossby wave packets embedded in upper troposphere westerly and by quasi-meridional Rossby wave packets in the background flow of the East Asian summer monsoon in the middle and lower troposphere.

The impact of aerosols on non‐precipitating marine stratocumulus. I: Model description and prediction of the indirect effect

Abstract: In this paper, the first of a two-part study, we use the UK Met Office large-eddy simulation model (LEM) with fully integrated size-bin-resolved cloud microphysics (BR-LEM) to investigate the effects of increasing cloud condensation nuclei (CCN) concentrations on non-precipitating marine stratocumulus. It is shown, as expected, that increasing CCN concentrations produces an increase in cloud-drop number concentration and a decrease in cloud-drop effective radius. However, for the case presented, we demonstrate that increasing CCN concentrations causes an increase in the rate of evaporative cooling at the cloud top, which drives stronger boundary-layer dynamics, leading to more cloud-top entrainment, which results in a reduction in boundary-layer relative humidity and a reduction in LWP with increasing CCN. Comparison of the BR-LEM simulations with LEM simulations that employ a simpler single-moment bulk scheme (Bulk-LEM) show that the bulk microphysics scheme fails to simulate this CCN--entrainment feedback and the associated reduction in liquid water path. It is shown that, for a very polluted case, the failure of the bulk microphysics to capture this evaporation--entrainment feedback results in a 60% overestimation of the indirect forcing estimate compared to the BR-LEM. We conclude that it is necessary to realistically simulate the dynamic feedbacks associated with increased CCN, otherwise the indirect will be overestimated. Copyright © 2008 Royal Meteorological Society

A New QRS Detection Algorithm Based on Empirical Mode Decomposition

Abstract: A new QRS complex detection algorithm based on the empirical mode decomposition (EMD) is proposed in this paper. The EMD can first decompose the ECG signal into a series of oscillatory components called intrinsic mode functions (IMFs). Then with the soft- threshold denoising method on the first three IMFs, we construct the detection layer that is suitable for QRS detection. Using the corresponding relationship between the feature points of QRS complex and the modulus maxima of the detection layer, the QRS complex detection is realized. The proposed EMD-based method was validated through experiments on the MIT-BIH arrhythmia database and a QRS detection rate of 99.34% was achieved.

Study on successions sequence of evergreen broad-leavedforest in Gutian Mountain of Zhejiang, Eastern China: species diversity

Abstract: Using the widely adopted scheme of space-for-time substitution for investigating 16 typical plots distributed as a pattern of contiguous grid quadrates within a sampling plot, the expressions of Shannon-Wiener index (H) for species diversity, Pielou index (J sw , J SI ) for evenness and Simpson index (D) for ecological dominance are employed to investigate the species diversity (SD) of four evergreen broadleaved communities in the successions sequence within the Nature Reserve of the Gutian Mountains. Results showed that in the successions process from the coniferous to the mixed coniferous-broadleaved, then to Schima superba and finally to Castanopsis eyrei forest, the arbor layer SD showed the Shannon-Wiener index (H) as 1.9670, 2.4975, 2.6140 and 2.4356, respectively, characterized by their rise before drop and the shrub (herb) layer SD shows the maximum to be in the mixed coniferous-broadleaved (coniferous) forest (H arriving at 2.8625 (1.5334)). In the vertical structure, on the other hand, for the sequenced coniferous forest, coniferous-broad mixed forest and Castnaopsis eyrei forest, the number of SD ranges in a decreasing order from the shrub, arbor to herb layer in contrast to the SD in a decreasing order of Schima superba forest ranging from the arbor to shrub and then to herb layer, and during the succession, the herb layer exhibits the maximum range of SD change among these layers, with its variation coefficients of 0.1572, 0.0806, 0.0899 and 0.1884 for H, J SW , J SI and D, in order, in sharp contrast to the minimal SD range in the shrub layer, with the corresponding figures of 0.0482, 0.0385, 0.0142, and 0.1553.

Efficient Quantum Secure Direct Communication with Authentication

Abstract: Two protocols of quantum direct communication with authentication [Phys. Rev. A 73 (2006) 042305] were recently indicated to be insecure against the authenticator Trent attacks [Phys. Rev. A 75 (2007) 026301]. We present two efficient protocols by using four Pauli operations, which are secure against inner Trent attacks as well as outer Eve attacks. Finally we generalize them to multiparty quantum direction communication.

Several error inequalities for a quadrature formula with a parameter and applications

Abstract: In this paper, we will derive several error inequalities for a quadrature formula with a parameter, which will not only provide some generalizations of the known results, but also give some other interesting quadrature formulae as special cases. Furthermore, sharp upper and lower error bounds for the double error inequalities are obtained. Applications in numerical integration are also given.