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Nanjing University of Information Science and Technology , formerly the Meteorology College of Nanjing University, was established in 1960 by the China Meteorological Administration, then changed the name into Nanjing Institute of Meteorology in May, 1963. NUIST is the oldest institution of higher learning of meteorology science in China.The administration of NUIST handed over from China Meteorological Administration to Jiangsu province in February, 2000. Its present name of Nanjing University of Information Science and Technology was adopted in May, 2004 with authorization by Jiangsu Government and the Ministry of Education of PRC.NUIST offers Associate, Bachelor, Master and Doctorate degree programs in areas including Atmospheric Science, Information Science and Technology, Environmental Science, Engineering, management, literature, economics, laws and agriculture.At Autumn 2010 more than 150 foreign students from 27 countries were studying at NUIST.External PartnershipThe university has established with Yale University, University of Maryland, University of Wisconsin, University of Detroit, University of Edinburgh, University of Reading, University of Toronto, University of Hamburg, Germany, Ireland, Waterford Institute of Technology, Queensland University of Technology 48 famous universities a partnership of scientific research and personnel training, exchange of visiting scholars and students enrolled in undergraduate and graduate departments. The school has the scholarships from Chinese government, Hanban, the Jiangsu province to recruit students. In 2009, the school was founded the "Confucius class" in Bahamas, and it became the fourth Confucius class that Jiangsu Province has found in overseas universities, in 2011, "Confucius class" successfully upgraded to "Confucius Institute". The school has a "World Meteorological Organization Regional Training Center", which has trained more than 1,600 meteorological technicians and managers for 134 countries and regions, and successfully hosted the Tenth World Meteorological Organization Conference of Education and Training and the third session of " quantitative precipitation estimation and forecasting " international conference . In 2010, the World Meteorological Organization Executive Council session on 62 certificates in recognition of the important contribution of the school to make the international meteorological training. Wikipedia.

Jiang D.,CAS Institute of Atmospheric Physics | Jiang D.,Chinese Academy of Sciences | Tian Z.,CAS Institute of Atmospheric Physics | Tian Z.,University of Chinese Academy of Sciences | And 2 more authors.
Climate Dynamics | Year: 2015

Towards a better insight into orbital-scale changes in global monsoon, here we examine global monsoon area (GMA) and precipitation (GMP) as well as GMP intensity (GMPI) in the mid-Holocene, approximately 6,000 years ago, using all available numerical experiments from the Paleoclimate Modelling Intercomparison Project. Compared to the reference period, both the mid-Holocene GMA and GMP increased in the majority of the 35 models chosen for analysis according to their ability, averaging 5.5 and 4.2 %, respectively, which were mainly due to the increase in monsoon area and precipitation over the boreal land and austral ocean. The mid-Holocene GMPI decreased in most models and by an average of 1.2 %, mainly due to the decrease in monsoon precipitation intensity over the boreal ocean and austral land. The mid-Holocene GMA, GMP, and GMPI all showed opposite changes both between the land and ocean in the northern or southern hemisphere and between the boreal and austral land or ocean. Orbital-induced changes in large-scale meridional temperature gradient and land–sea thermal contrast are the underlying mechanisms, and the presence of an interactive ocean has an amplifying effect in the boreal land monsoon areas overall. Qualitatively, the model–data comparison indicates agreement in the boreal land monsoon areas and South America but disagreement in southern Africa and northern Australia. © 2014, Springer-Verlag Berlin Heidelberg.

Zhu K.,University of Oklahoma | Pan Y.,University of Oklahoma | Pan Y.,Nanjing University of Information Science and Technology | Xue M.,University of Oklahoma | And 5 more authors.
Monthly Weather Review | Year: 2013

A regional ensemble Kalman filter (EnKF) system is established for potential Rapid Refresh (RAP) operational application. The system borrows data processing and observation operators from the gridpoint statistical interpolation (GSI), and precalculates observation priors using the GSI. The ensemble square root Kalman filter (EnSRF) algorithm is used, which updates both the state vector and observation priors. All conventional observations that are used in the operational RAP GSI are assimilated. To minimize computational costs, the EnKF is run at 1/3 of the operational RAP resolution or about 40-km grid spacing, and its performance is compared to the GSI using the same datasets and resolution. Short-range (up to 18 h, the RAP forecast length) forecasts are verified against soundings, surface observations, and precipitation data. Experiments are run with 3-hourly assimilation cycles over a 9-day convectively active retrospective period from spring 2010. The EnKF performance was improved by extensive tuning, including the use of height-dependent covariance localization scales and adaptive covariance inflation. When multiple physics parameterization schemes are employed by the EnKF, forecast errors are further reduced, especially for relative humidity and temperature at the upper levels and for surface variables. The best EnKF configuration produces lower forecast errors than the parallel GSI run. Gilbert skill scores of precipitation forecasts on the 13-km RAP grid initialized from the 3-hourly EnKF analyses are consistently better than those from GSI analyses. © 2013 American Meteorological Society.

Wu H.,Yunnan University | He J.,Nanjing University of Information Science and Technology | Pei Y.,Yunnan University
Journal of the American Society for Information Science and Technology | Year: 2010

In this article, we propose to apply the topic model and topic-level eigenfactor (TEF) algorithm to assess the relative importance of academic entities including articles, authors, journals, and conferences. Scientific impact is measured by the biased PageRank score toward topics created by the latent topic model. The TEF metric considers the impact of an academic entity in multiple granular views as well as in a global view. Experiments on a computational linguistics corpus show that the method is a useful and promising measure to assess scientific impact. © 2010 ASIS&T.

Wen N.,Nanjing University of Information Science and Technology | Liu Z.,University of Wisconsin - Madison | Liu Q.,Ocean University of China
Journal of Applied Meteorology and Climatology | Year: 2013

Most previous studies have proven the local negative heat flux feedback (the surface heat flux response to SST anomalies) in the midlatitude areas. However, it is uncertain whether a nonlocal heat flux feedback can be observed. In this paper, the generalized equilibrium feedback assessment (GEFA) method is employed to examine the full surface turbulent heat flux response to SST in the North Atlantic Ocean using NCEP-NCAR reanalysis data. The results not only confirm the dominant local negative feedback, but also indicate a robust nonlocal positive feedback of the Gulf Stream Extension (GSE) SST to the downstream heat flux in the subpolar region. This nonlocal feedback presents a strong seasonality, with response magnitudes of 16 W m-2 K-1 in winter and 1.2 W m-2 K-1 in summer. Further study indicates that the nonlocal effect is initiated by the adjustments of the downstream surface wind to the GSE SST anomalies. © 2013 American Meteorological Society.

Qin Z.,Nanjing University of Information Science and Technology | Qin Z.,Florida State University | Zou X.,Florida State University | Weng F.,National Oceanic and Atmospheric Administration
Monthly Weather Review | Year: 2013

The Geostationary Operational Environmental Satellites (GOES) provide high-resolution, temporally continuous imager radiance data over the West Coast (GOES-West currently known as GOES-11) and East Coast (GOES-East currently GOES-12) of the United States. Through a real case study, benefits of adding GOES-11/12 imager radiances to the satellite data streams inNWPsystems for improved coastal precipitation forecasts are examined. The Community Radiative Transfer Model (CRTM) is employed for GOES imager radiance simulations in the National Centers for Environmental Prediction (NCEP) gridpoint statistical interpolation (GSI) analysis system. The GOES imager radiances are added to conventional data for coastal quantitative precipitation forecast (QPF) experiments near the northern Gulf of Mexico and the derived precipitation threat score was compared with those from six other satellite instruments. It is found that the GOES imager radiance produced better precipitation forecasts than those from any other satellite instrument. However, when GOES imager radiance and six different types of satellite instruments are all assimilated, the score becomes much lower than the individual combination of GOESand any other instrument. Our analysis shows that an elimination of Advance Microwave Sounding Unit-B (AMSU-B)/Microwave Humidity Sounder (MHS) data over areas where GOES detects clouds significantly improved the forecast scores from AMSU-B/MHS data assimilation. © 2013 American Meteorological Society.

Wen X.-F.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Meng Y.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Zhang X.-Y.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | Sun X.-M.,CAS Beijing Institute of Geographic Sciences and Nature Resources Research | And 2 more authors.
Atmospheric Measurement Techniques | Year: 2013

Isotope ratio infrared spectroscopy (IRIS) provides an in situ technique for measuring δ13C in atmospheric CO2. A number of methods have been proposed for calibrating the IRIS measurements, but few studies have systematically evaluated their accuracy for atmospheric applications. In this study, we carried out laboratory and ambient measurements with two commercial IRIS analyzers and compared the accuracy of four calibration strategies.We found that calibration based on the 12C and 13C mixing ratios (Bowling et al., 2003) and on linear interpolation of the measured delta using the mixing ratio of the major isotopologue (Lee et al., 2005) yielded accuracy better than 0.06 ‰. Over a 7-day atmospheric measurement in Beijing, the two analyzers agreed to within -0.02 ± 0.18 ‰ after proper calibration. However, even after calibration the difference between the two analyzers showed a slight correlation with concentration, and this concentration dependence propagated through the Keeling analysis, resulting in a much larger difference of 2.44 ‰for the Keeling intercept. The high sensitivity of the Keeling analysis to the concentration dependence underscores the challenge of IRIS for atmospheric research. © Author(s) 2013.

Fenglin X.,Nanjing University of Information Science and Technology
Optik | Year: 2016

Pure and Fe modified tetrapod-shaped ZnO whiskers with various Fe concentrations have been synthesized by a simple thermal evaporation method. The structure, morphology, photocatalytic and photoluminescence properties of the samples are investigated. X-ray diffraction (XRD) patterns show that pure and 1% Fe modified samples possess a wurtzite hexagonal crystal structure without any second phase. When the modifying level increases, additional two weak diffraction peaks corresponding to Fe2O3 and ZnFe2O4 are observed. Scanning electron microscopy (SEM) measurement exhibits that all samples have tetrapod-like whisker structure, when modified with Fe, there are several small tips and particles attached to the arm. The photocatalytic tests show that 1% Fe modified tetrapod-shaped ZnO whisker has the best photocatalytic activity in degradation of Rhodamine B (RhB). The luminescence properties show that all samples have ultraviolet emission at 381 nm, weak violet emission and broad green-yellow emission band, the emission mechanisms are discussed in detail. © 2015 Elsevier GmbH. All rights reserved.

Yang S.,Nanjing University of Information Science and Technology | Zou X.,Florida State University
Journal of Climate | Year: 2013

Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) radio occultation (RO) refractivity profiles in altostratus and nimbostratus clouds from 2007 to 2010 are first identified based on collocated CloudSat data. Vertical temperature profiles in these clouds are then retrieved from cloudy refractivity profiles. Contributions of cloud liquid water content and ice water content are also included in the retrieval algorithm. The temperature profiles and their lapse rates are compared with those from a standard GPSROwet retrieval without including cloud effects. On average, the temperatures from cloudy retrieval are about 0.5-1.0K warmer than the GPS RO wet retrieval, except for the altitudes near the nimbostratus base. The differences of temperature between the two methods are largest in summer and smallest in winter. The lapse rate in altostratus clouds is around 6.58-7.58Ckm21 and does not vary greatly with height. On the contrary, the lapse rate increases significantly with height in nimbostratus clouds, from about 2.58-3.58Ckm21 near the cloud base to about 5.08-6.08Ckm21 at cloud center and 6.58-7.58Ckm21 below the cloud top. Seasonal variability of lapse rate derived from the cloudy retrieval is larger than that derived from the wet retrieval. The lapse rate within clouds is smaller in summer and larger in winter. The mean lapse rate decreases with temperature in all seasons. © 2013 American Meteorological Society.

Qi Y.,University of Oklahoma | Qi Y.,Nanjing University of Information Science and Technology | Zhang J.,National Oceanic and Atmospheric Administration
Journal of Hydrometeorology | Year: 2013

The melting of aggregated snow/crystals often results in an enhancement of the reflectivity observed by weather radars, and this is commonly referenced as the bright band (BB). The locally high reflectivity often causes overestimation in radar quantitative precipitation estimates (QPE) if no appropriate correction is applied. When the melting layer is high, a complete BB layer profile (including top, peak, and bottom) can be observed by the ground radar, and a vertical profile of reflectivity (VPR) correction can be made to reduce the BB impact. When a melting layer is near the ground and the bottom part of the bright band cannot be observed by the ground radar, a VPR correction cannot be made directly from the Weather Surveillance Radar-1988 Doppler (WSR-88D) radar observations. This paper presents a new VPR correction method under this situation. From high-resolution precipitation profiler data, an empirical relationship between BB peak and BB bottom is developed. The empirical relationship is combined with the apparent BB peak observed by volume scan radars and the BB bottom is found. Radar QPEs are then corrected based on the estimated BB bottom. The new method was tested on 13 radars during seven low brightband events over different areas in the United States. It is shown to be effective in reducing the radar QPE overestimation under low brightband situations. © 2013 American Meteorological Society.

Miao G.,Nanjing University of Information Science and Technology | Ma Q.,Nanjing University of Science and Technology
Neurocomputing | Year: 2015

This paper investigates group consensus for the first-order multi-agent systems with nonlinear input constraints. And group consensus protocols for discrete-time and continuous-time multi-agent systems are proposed. By using the tools of the Lyapunov function, LaSalle[U+05F3]s invariance principle and graph theory, group consensus/finite-time group consensus conditions are obtained. Finally, two simulation examples are provided to illustrate the effectiveness of our proposed methods in the paper. © 2015 Elsevier B.V.

Mantelero A.,Nanjing University of Information Science and Technology | Mantelero A.,Polytechnic University of Turin
Computer Law and Security Review | Year: 2016

In the big data era, new technologies and powerful analytics make it possible to collect and analyse large amounts of data in order to identify patterns in the behaviour of groups, communities and even entire countries. Existing case law and regulations are inadequate to address the potential risks and issues related to this change of paradigm in social investigation. This is due to the fact that both the right to privacy and the more recent right to data protection are protected as individual rights. The social dimension of these rights has been taken into account by courts and policymakers in various countries. Nevertheless, the rights holder has always been the data subject and the rights related to informational privacy have mainly been exercised by individuals. This atomistic approach shows its limits in the existing context of mass predictive analysis, where the larger scale of data processing and the deeper analysis of information make it necessary to consider another layer, which is different from individual rights. This new layer is represented by the collective dimension of data protection, which protects groups of persons from the potential harms of discriminatory and invasive forms of data processing. On the basis of the distinction between individual, group and collective dimensions of privacy and data protection, the author outlines the main elements that characterise the collective dimension of these rights and the representation of the underlying interests. © 2016 Alessandro Mantelero, Published by Elsevier Ltd. All rights reserved.

Liu H.,University of Auckland | Chen Y.,Sichuan University | Zhao H.,Nanjing University of Information Science and Technology | Wei S.,Sichuan University | Gao W.,University of Auckland
Journal of Alloys and Compounds | Year: 2010

The strontium (Sr) addition to the Mg-5 wt.%Sn alloy results in grain refinement and the formation of a rod-shaped and a bone-shaped MgSnSr intermetallic phase which are mainly straddle on the grain boundaries. The yield strength is improved, while the tensile strength and elongation first increased, and then decreased with a large addition of Sr. Optimum mechanical properties at ambient temperature are obtained at a content of 2.14 wt.%Sr. Tensile properties of the alloys at elevated temperatures are also improved, and the decrease of strength at elevated temperature slowed down with increasing Sr addition, indicating that Sr can improve the thermal stability of Mg-Sn alloys. © 2010 Elsevier B.V. All rights reserved.

Lee S.-S.,University of Hawaii at Manoa | Wang B.,University of Hawaii at Manoa | Wang B.,Nanjing University of Information Science and Technology
Climate Dynamics | Year: 2015

The boreal summer intraseasonal oscillation (BSISO) has two major activity centers, the northern Indian Ocean and tropical Western North Pacific, which dominate the monsoon intraseasonal variability over South Asia and East Asia, respectively. The spatial–temporal structures of BSISO over the Indian Ocean (10°S–30°N, 60°–105°E) (IOISO) and Western Pacific (10°S–30°N, 105°–150°E) (WPISO) are examined by corresponding the leading modes of daily OLR and 850-hPa zonal wind (U850). The IOISO features a northeastward propagation with a 30–45 days energy peak and the first principal component (PC1) has maximum variance in May, while the WPISO propagates northward with a broad spectral peak on 10–60 days and the PC1 has maximum variance in August. Because of the large regional differences, two regional indices, the IOISO index and WPISO index, are defined by their corresponding first two leading PCs. The combined IOISO–WPISO index captures about 30 % (10 %) of U850 (OLR) daily variance over the entire IO–WP region (10°S–30°N, 60°–150°E), which doubles that captured by the Madden–Julian Oscillation (MJO) index (Wheeler and Hendon 2004) and is 50 % higher than that captured by the BSISO index (Lee et al. 2013). The combined index also shows superior performance in representing biweekly and pentad-mean variations in the Asian-Pacific summer monsoon region (north of 10°N). The predictability/prediction skill and simulated principal modes of two regional BSISO indices are explored by using data derived from the Intraseasonal Variability Hindcast Experiment project. The major regional modes are reasonably well captured, but the forecasted fractional variances of the leading modes and variability center’s locations exhibit significant deficiencies. The multi-model mean estimate of the predictability is 40–45 days for the IOISO index, whereas 33–37 days for the WPISO index. The less predictable WPISO is likely due to the existence of its significant biweekly component. The multi-model mean prediction skill is significantly higher with large initial amplitude (~20 days for two indices) than that with small initial amplitude (~11 days), suggesting that the prediction for development of BSISO is much more difficult than the prediction for mature BSISO disturbances’ propagation. © 2015 Springer-Verlag Berlin Heidelberg

Yan S.-Y.,Nanjing University of Information Science and Technology
Dianzi Yu Xinxi Xuebao/Journal of Electronics and Information Technology | Year: 2014

It always takes a very high computational cost to build a Boosting cascade classifier. To speed up the training procedure of the Boosting cascade, this paper proposes an extended training method which utilizes the sharing information among different stage classifiers. The proposed method takes advantage of the sharing information among different stage classifiers at two levels. First, at the classifier level, the last stage classifier is taken as the first feature, and is re-used to learn a new weak classifier to adapt the newly collected training samples of the current stage. Secondly, at the feature level, all the selected features from all the previous stage classifiers are re-used to learn new weak classifiers which adapt to the newly collected training samples of the current stage. Finally, the newly learned weak classifiers and newly selected features are added in the current stage classifier. The experimental results on frontal face detection show that the proposed method improves the training speed of the Boosting cascade classifier largely. The training speed of the proposed method is about 10 times faster than that of the traditional method. To be exact, the training time of a frontal face detector is reduced from about 3 days to 8 hours.

Shao L.,Nanjing University of Information Science and Technology | Shao L.,University of Sheffield | Jones S.,University of Sheffield | Li X.,Chinese Academy of Sciences
IEEE Transactions on Circuits and Systems for Video Technology | Year: 2014

As digital video databases grow, so grows the problem of effectively navigating through them. In this paper we propose a novel content-based video retrieval approach to searching such video databases, specifically those involving human actions, incorporating spatio-temporal localization. We outline a novel, highly efficient localization model that first performs temporal localization based on histograms of evenly spaced time-slices, then spatial localization based on histograms of a 2-D spatial grid. We further argue that our retrieval model, based on the aforementioned localization, followed by relevance ranking, results in a highly discriminative system, while remaining an order of magnitude faster than the current state-of-the-art method. We also show how relevance feedback can be applied to our localization and ranking algorithms. As a result, the presented system is more directly applicable to real-world problems than any prior content-based video retrieval system. © 2014 IEEE.

Sharma A.,Texas Tech University | Weindorf D.C.,Texas Tech University | Wang D.,Nanjing University of Information Science and Technology | Chakraborty S.,Ramakrishna Mission Vivekananda University
Geoderma | Year: 2015

Soil cation exchange capacity (CEC) is an important measure of soil fertility, owing to the large number of plant essential nutrients which are taken up by plants as cations. However, current methods for evaluating soil CEC are arduous and require analysis in a laboratory. Portable X-ray fluorescence (PXRF) spectrometry is a proximal sensing technique which provides elemental data in-situ, in seconds. This study examined the potential of using PXRF for soil CEC prediction by evaluating 450 soil samples from California and Nebraska, USA representing a wide variety of soil textures found in active farm fields. Multiple linear regression was applied to a modeling dataset to establish the relationship between lab-determined CEC and PXRF elemental data. A second model also included auxiliary input data (soil clay, pH, organic matter) as potential modeling variables. Both models were shown to perform similarly, with the auxiliary input model providing slightly higher R2 (0.926 vs. 0.908) and slightly lower RMSEs (2.236 vs. 2.498) compared to pure elemental data models. Independent validation datasets were compelling for both pure elemental models (0.904) and auxiliary input models (0.953). Summarily, PXRF was able to predict soil CEC accurately, thereby minimizing the need for lab-based CEC data for many applications. © 2014 Elsevier B.V.

Li C.,Nanjing University of Information Science and Technology | Sprott J.C.,University of Wisconsin - Madison | Thio W.,Ohio State University
IEEE Transactions on Circuits and Systems II: Express Briefs | Year: 2014

When the polarity information in diffusionless Lorenz equations is preserved or removed, a new piecewise linear hyperchaotic system results with only signum and absolute-value nonlinearities. Dynamical equations have seven terms without any quadratic or higher order polynomials and, to our knowledge, are the simplest hyperchaotic system. Therefore, a relatively simple hyperchaotic circuit using diodes is constructed. The circuit requires no multipliers or inductors, as are present in other hyperchaotic circuits, and it has not been previously reported. © 2014 IEEE.

Li C.,Nanjing University of Information Science and Technology | Li C.,Nanjing Institute of Technology | Li C.,University of Wisconsin - Madison | Sprott J.C.,Nanjing Institute of Technology
International Journal of Bifurcation and Chaos | Year: 2014

In this paper, the dynamical behavior of the Lorenz system is examined in a previously unexplored region of parameter space, in particular, where r is zero and b is negative. For certain values of the parameters, the classic butterfly attractor is broken into a symmetric pair of strange attractors, or it shrinks into a small attractor basin intermingled with the basins of a symmetric pair of limit cycles, which means that the system is bistable or tristable under certain conditions. Although the resulting system is no longer a plausible model of fluid convection, it may have application to other physical systems. © World Scientific Publishing Company.

Liu C.,Tongji University | Hu C.,University of Texas at Austin | Liu Q.,Nanjing University of Information Science and Technology | Aggarwal J.K.,University of Texas at Austin
Neurocomputing | Year: 2013

Video event description is an important research topic in video analysis with a vast amount of applications, such as visual surveillance, video retrieval, video annotation, video database indexing, and interactive system. In this paper, we present a framework for automated video event description, which features fused with the context knowledge to provide accurate and reliable event description. The processing framework is designed to describe the event and recognize objects activities composed of four components: object detection, classification, tracking, and semantic event description. Our contribution is to integrate the contextual cues into these components to facilitate the semantic video event description. Furthermore, in the tracking part, a novel adaptive shape kernel based mean shift tracking algorithm is proposed to improve object tracking performance under object deformation and background clutter. In the experiments, we show attractive experimental results, highlighting the system efficiency and tracking capability by using our video event description system on a real-world video for video event understanding application. © 2012 Elsevier B.V.

Wu Y.,Nanjing University of Information Science and Technology | Shen B.,Purdue University | Ling H.,Temple University
IEEE Transactions on Circuits and Systems for Video Technology | Year: 2014

In visual tracking, holistic and part-based representations are both popular choices to model target appearance. The former is known for great efficiency and convenience, while the latter for robustness against local appearance or shape variations. Based on nonnegative matrix factorization (NMF), we propose a novel visual tracker that takes advantage of both groups. The idea is to model the target appearance by a nonnegative combination of nonnegative components learned from examples observed in previous frames. To adjust NMF to the tracking context, we include sparsity and smoothness constraints in addition to the nonnegativity one. Furthermore, an online iterative learning algorithm, together with a proof of convergence, is proposed for efficient model updating. Putting these ingredients together with a particle filter framework, the proposed tracker, constrained online nonnegative matrix factorization (CONMF), achieves robustness to challenging appearance variations and nontrivial deformations while running in real time. We evaluate the proposed tracker on various benchmark sequences containing targets undergoing large variations in scale, pose, or illumination. The robustness and efficiency of CONMF is validated in comparison with several state-of-the-art trackers. © 2014 IEEE.

McKinnon C.,University of Reading | McKinnon C.,Nanjing University of Information Science and Technology
Climatic Change | Year: 2015

The fact of a carbon budget given commitment to limiting global-mean temperature increase to below 2 °C warming relative to pre-industrial levels makes CO2 emissions a scarce resource. This fact has significant consequences for the ethics of climate change. The paper highlights some of these consequences with respect to (a) applying principles of distributive justice to the allocation of rights to emissions and the costs of mitigation and adaptation, (b) compensation for the harms and risks of climate change, (c) radical new ideas about a place for criminal justice in tackling climate change, and (d) catastrophe ethics. © 2015 Springer Science+Business Media Dordrecht

Zhao H.,Nanjing University of Information Science and Technology
Theoretical and Applied Climatology | Year: 2015

Changes in tropical cyclone (TC) activity over the western North Pacific (WNP) basin between the Modoki and canonical El Niño years have been simulated and examined in this study based on a downscaling technique. The downscaling technique is used for generating synthetic TCs based on TC formation, TC track, and TC intensity models. Results suggest that the downscaling technique can well simulate the spatial distribution of TC activity during the two types of El Niño years and their differences. It is found that the observed changes in TC tracks during the two types of El Niño years are mainly due to the combined effects of changes in TC formation locations and large-scale steering flows. Further examinations have shown that changes in large-scale steering flows play a more important role than changes in TC formation locations. These results are in accordance with the cyclonic circulation anomaly found during the Modoki El Niño years compared to that during the canonical El Niño years. Numerical simulations further suggest that changes in TC tracks between the two types of El Niño years appear to be the most important factor affecting the TC intensity change. Compared to that during the Modoki El Niño years, TC formation is enhanced in the south quadrant of the WNP basin and more TCs take a northwestward track during the canonical El Niño years, leading to a longer TC lifespan and greater TC intensity. © 2015 Springer-Verlag Wien

Bukenya J.O.,Nanjing University of Information Science and Technology | Bukenya J.O.,Alabama A&M University | Ssebisubi M.,Aquaculture Management Consultants
Fisheries Science | Year: 2014

This paper looks at price integration in the aquaculture and wild-harvested African catfish market channels in Uganda. The issue of integration between the two market channels is important because African catfish has become an important traded species in Uganda with exports to regional markets rising even faster than production, yet limited research has been undertaken to understand price formation in the supply chain. The analysis draws on monthly price data from January 2006 to August 2013, and applies threshold autoregressive approaches to test for the existence of a long-run relationship and price asymmetry and to determine the time path needed for shocks to be transmitted from one market channel to the other. The results show that, over the studied period prices in both market channels are linked in the long-run, implying that farm-raised catfish forms part of the same market as wild-harvested catfish in the country. The findings have strong implications for aquaculture producers and artisanal fishers as they can serve as a basis for more efficient farm management and marketing decisions. © 2014, Japanese Society of Fisheries Science.

Li C.,Nanjing University of Information Science and Technology | Li C.,Nanjing Institute of Technology | Sprott J.C.,University of Wisconsin - Madison | Thio W.,Ohio State University
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2015

A partial and complete piecewise linearized version of the Lorenz system is proposed. The linearized versions have an independent total amplitude control parameter. Additional further linearization leads naturally to a piecewise linear version of the diffusionless Lorenz system. A chaotic circuit with a single amplitude controller is then implemented using a new switch element, producing a chaotic oscillation that agrees with the numerical calculation for the piecewise linear diffusionless Lorenz system. © 2015 Elsevier B.V. All rights reserved.

Dong B.,Nanjing Institute of Industry Technology | Chen J.,Nanjing University of Information Science and Technology
International Journal of Sensor Networks | Year: 2015

This paper presents an approach, called LBS, for modelling and implementing the architecture of wireless sensor networks (WSNs) publish/subscribe (Pub/Sub) applications using a local broker subcomponent (LBS) model. Considering the reconfigurability of WSNs applications which is necessary for WSNs middleware, a graph-oriented local broker subcomponent (GOLBS) model is defined based on the LBS model by integrated WSNs middleware with Pub/Sub. Focusing on the evolution specification of reconfiguration and non-predefined dynamic reconfiguration, we define the notations of what is the GOLBS' graph grammars and GOLBS' graph, and show a derivative procedure. We design and implement a prototype system on GOLBS, called Pub/Sub-GOLBS. Performance evaluations imply that GOLBS can easily be constructed, while ensuring good reconfigurability. Copyright © 2015 Inderscience Enterprises Ltd.

Ma X.,Nanjing University of Information Science and Technology | Ma X.,Albany Research Center | Yu F.,Albany Research Center
Tellus, Series B: Chemical and Physical Meteorology | Year: 2015

Recent AeroCom phase II experiments showed a large diversity in aerosol optical depth (AOD) among 16 detailed global aerosol models, which contributes to the large uncertainty in the predicted aerosol radiative forcing. The GEOS-Chem-APM, a global size-resolved aerosol model, can be considered as a representative AeroCom II model. In this study, multi-year AOD data (2004-2012) from ground-based Aerosol Robotic Network (AERONET) measurements and Moderate Resolution Imaging Spectroradiometer (MODIS), Multiangle Imaging SpectroRadiometer (MISR) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite retrievals are used to evaluate the performance of GEOS-Chem-APM in capturing observed seasonal and spatial AOD variations. Compared to the observations, the modelled AOD is overall good over land, but quite low over ocean possibly due to low sea salt emission in the model and/or higher AOD in satellite retrievals, specifically MODIS and MISR. We chose 72 AERONET sites having at least 36 months data available and representative of high spatial domain to compare with the model and satellite data. Comparisons in various representative regions show that the model overall agrees well in the major anthropogenic emission regions, such as Europe, East Asia and North America. Relative to the observations, the modelled AOD is systematically lower in biomass burning regions such as South Africa and South America possibly due to uncertainties in emission inventory, but slightly higher in North Africa likely associated with stronger dust emissions in the model. The model is able to capture the realistic seasonal cycle in all regions, including the peak of AOD in major dust events months and biomass burning seasons. The simulated inter-annual variability is overall consistent with the observations, which is distinctly shown in South Africa and South America with strong inter-annual variability compared to other regions. © 2014 Cecilia Fernbrant et al.

Zhang X.-H.,Nanjing University of Information Science and Technology
Proceedings - 4th International Conference on Information and Computing, ICIC 2011 | Year: 2011

The classification accuracy of mangrove is always low due to the similarity of spectra between mangrove and water-vegetation mixed pixels. Greenness and wetness were extracted by K-T transformation based on Landsat5/TM imagery. The greenness and wetness can significantly improve the separability between mangrove and water-vegetation mixed pixels by comparison with NDVI, TM3/TM5,TM5/TM4, which always were employed by other researchers. The Kappa coefficient, commission error of mangrove class were 0.90, 7.9%, respectively, by using decision tree method. © 2011 IEEE.

Wu Y.,Nanjing University of Information Science and Technology | Lim J.,Hanyang University | Yang M.-H.,University of California at Merced
IEEE Transactions on Pattern Analysis and Machine Intelligence | Year: 2015

Object tracking has been one of the most important and active research areas in the field of computer vision. A large number of tracking algorithms have been proposed in recent years with demonstrated success. However, the set of sequences used for evaluation is often not sufficient or is sometimes biased for certain types of algorithms. Many datasets do not have common ground-truth object positions or extents, and this makes comparisons among the reported quantitative results difficult. In addition, the initial conditions or parameters of the evaluated tracking algorithms are not the same, and thus, the quantitative results reported in literature are incomparable or sometimes contradictory. To address these issues, we carry out an extensive evaluation of the state-of-the-art online object-tracking algorithms with various evaluation criteria to understand how these methods perform within the same framework. In this work, we first construct a large dataset with ground-truth object positions and extents for tracking and introduce the sequence attributes for the performance analysis. Second, we integrate most of the publicly available trackers into one code library with uniform input and output formats to facilitate large-scale performance evaluation. Third, we extensively evaluate the performance of 31 algorithms on 100 sequences with different initialization settings. By analyzing the quantitative results, we identify effective approaches for robust tracking and provide potential future research directions in this field. © 1979-2012 IEEE.

Wu J.,Nanjing University of Aeronautics and Astronautics | Yuan S.,Nanjing University of Aeronautics and Astronautics | Ji S.,Nanjing University of Information Science and Technology | Zhou G.,Changzhou University | And 2 more authors.
Expert Systems with Applications | Year: 2010

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. © 2009 Elsevier Ltd. All rights reserved.

Zhang J.,National Oceanic and Atmospheric Administration | Qi Y.,Nanjing University of Information Science and Technology | Qi Y.,University of Oklahoma
Journal of Hydrometeorology | Year: 2010

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 consistently well for radars in flat land regions because of the relatively uniform spatial distributions of the BB in those areas. For radars in mountainous regions, the performance of the correction is mixed because of limited radar visibility in addition to large spatial variations of the vertical precipitation structure due to underlying topography. © 2010 American Meteorological Society.

Li C.,Nanjing University of Information Science and Technology | Li C.,Nanjing Institute of Technology | Li C.,University of Wisconsin - Madison | Sprott J.C.,University of Wisconsin - Madison
Nonlinear Dynamics | Year: 2014

Nonlinear dynamical systems often have multiple stable states and thus can harbor coexisting and hidden attractors that may pose an inconvenience or even hazard in practical applications. Amplitude control provides one method to detect these coexisting attractors, and it explains the unpredictable and irreproducible behavior that sometimes occurs in carefully engineered systems. In this paper, two regimes of amplitude control are described to illustrate the method for detecting multistability and possible coexisting or hidden attractors. © 2014, Springer Science+Business Media Dordrecht.

Jiang F.,Nanjing University of Information Science and Technology | Jiang F.,University of Science and Technology Beijing
Applied Surface Science | Year: 2016

Smooth tungsten coatings were prepared at current density below 70 mA cm-2 by electrodeposition on molybdenum substrate from Na2WO4-WO3 -melt at 1173 K in air atmosphere. As the current density reached up to 90 mA cm-2, many significant nodules were observed on the surface of the coating. Surface characterization, microstructure and mechanical properties were performed on the tungsten coatings. As the increasing of current density, the preferred orientation of the coatings changed to (2 0 0). All coatings exhibited columnar-grained-crystalline. There was about a 2 μm thick diffusion layer between tungsten coating and molybdenum substrate. The bending test revealed the tungsten coating had -good bonding strength with the molybdenum substrate. There is a down trend of the grain size of the coating on molybdenum as the current density increased from 30 mA cm-2 to 50 mA cm-2. The coating obtained at 50 mA cm-2 had a minimum grain size of 4.57 μm, while the microhardness of this coating reached to a maximum value of 495 HV. © 2015 Elsevier B.V. All rights reserved.

Wang H.,Northeastern University China | Yang S.,Brunel University | Yang S.,Nanjing University of Information Science and Technology | Ip W.H.,Hong Kong Polytechnic University | Wang D.,Northeastern University China
International Journal of Systems Science | Year: 2012

Many real-world optimisation problems are both dynamic and multi-modal, which require an optimisation algorithm not only to find as many optima under a specific environment as possible, but also to track their moving trajectory over dynamic environments. To address this requirement, this article investigates a memetic computing approach based on particle swarm optimisation for dynamic multi-modal optimisation problems (DMMOPs). Within the framework of the proposed algorithm, a new speciation method is employed to locate and track multiple peaks and an adaptive local search method is also hybridised to accelerate the exploitation of species generated by the speciation method. In addition, a memory-based re-initialisation scheme is introduced into the proposed algorithm in order to further enhance its performance in dynamic multi-modal environments. Based on the moving peaks benchmark problems, experiments are carried out to investigate the performance of the proposed algorithm in comparison with several state-of-the-art algorithms taken from the literature. The experimental results show the efficiency of the proposed algorithm for DMMOPs. © 2012 Taylor & Francis.

Jiang T.,Nanjing University of Information Science and Technology | Yang Z.,Jiangsu JIQUN Information Group Industry CO
Procedia Engineering | Year: 2011

In this paper our experiences using a wireless sensor network to monitor the coal mines are described. The multi-sensor in one node can capture a variety of environmental data, including the vibration of the mine, the mine temperature, humidity and gas concentration, and environmental parameters control operation of the fan. Network consists of many wireless sensor nodes. Mine safety monitoring program has been developed to save the received data from sink nodes and show it on real time and analyze all kinds of information for decision function. © 2011 Published by Elsevier Ltd.

Wang D.,Nanjing University of Information Science and Technology
Advanced Materials Research | Year: 2012

In the process of rapid urbanization building, the natural environment pollution threat to the health of residents; on the other hands, the limit living spaces constraints the residents physical activities. Environmental degradation is rooted in the city's extensive development, the powerless regulation of environmental and the weak awareness of environmental. Response to environmental degradation on health effects, we have three active intervention paths: promote the health of urban construction, building green, livable living environment, promote healthy lifestyles. © (2012) Trans Tech Publications, Switzerland.

Wu W.C.,University of New South Wales | Ao Z.M.,The Clean Tech Center | Yang C.H.,Nanjing University of Information Science and Technology | Li S.,Nanjing University of Science and Technology | And 3 more authors.
Journal of Materials Chemistry C | Year: 2015

Hydrogenation of silicene has been shown to be an efficient way to open the band gap of silicene and manipulate its electronic properties for application in electronic devices. However, the reaction energy barrier of silicene hydrogenation is quite high, which prevents the occurrence of this chemical reaction. Using density functional theory calculations, we propose an alternative approach to reduce the energy barrier, thus facilitating hydrogenation of silicene. Our results demonstrate that biaxial strain and uniaxial tensile strain along the armchair direction can reduce the energy barrier of dissociative H2 adsorption on silicene significantly, and the barrier decreases as the strains increase. However, the biaxial strain has a better effect on the energy barrier reduction. It is found that the barrier reduces from 1.71 to 0.24 eV when the biaxial strain reaches the critical value of about 12%, above which the structure of silicene after hydrogenation would be destroyed. In this way, the reaction time for the hydrogenation of silicene can be reduced significantly from 8.06 × 1016 to 1.68 × 10-8 s. The mechanism of the effect of tensile strains can be understood through analysing the density of states of the system and atomic charge transfer during hydrogenation. This journal is © The Royal Society of Chemistry.2015.

Han Y.,Nanjing University of Information Science and Technology | Zou X.,University of Maryland University College | Weng F.,The Center for Satellite Applications and Research
Geophysical Research Letters | Year: 2015

A new methodology is developed to detect the cloud structures at different vertical levels using the dual oxygen absorption bands located near 60GHz and 118GHz, respectively. Observations from Microwave Temperature Sounder (MWTS) and Microwave Humidity Sounder (MWHS) on board the recently launched Chinese FengYun-3C satellite are used to prove the concept. It is shown that a paired oxygen MWTS and MWHS sounding channel with the same peak weighting function altitude allows for detecting the vertically integrated cloud water path above that level. A cloud emission and scattering index (CESI) is defined using dual oxygen band measurements to indicate the amounts of cloud liquid and ice water paths. The CESI distributions from three paired channels reveal unique three-dimensional structures of clouds and precipitation within Super Typhoon Neoguri that occurred in July 2014. © 2015 The Authors.

Xian F.L.,Nanjing University of Science and Technology | Xu L.H.,Nanjing University of Information Science and Technology | Wang X.X.,Nanjing University of Science and Technology | Li X.Y.,Nanjing University of Science and Technology
Crystal Research and Technology | Year: 2012

ZnO thin films with various Co doping levels (0%, 1%, 3%, 5%, 8%, respectively) have been synthesized by sol gel spin coating method on glass substrates. XRD and XPS studies of the films reveal that cobalt ions are successfully doped into ZnO crystal lattice without changing the hexagonal wurtzite structure. The morphologies are studied by SEM and AFM and show wrinkle network structures with uniform size distribution. With Co doping concentration increasing, the wrinkle network width decreases gradually. The transmittance spectra indicate that Co doping can effectively reduce the optical bandgap of ZnO thin films. Photoluminescence show that all samples have ultraviolet, violet and green emission. When Co doping concentration increases up to 5%, the intensity of violet emission is greatly increased and a strong deep blue emission centered at 439 nm appears. The ferromagnetism of all samples was observed at room temperature. The emission mechanisms and ferromagnetism origination are discussed in detail. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liu Q.,Nanjing University of Information Science and Technology | Linge N.,University of Salford | Lynch V.,University of Salford
IEEE Transactions on Consumer Electronics | Year: 2012

A domestic energy management system provides effective positive behaviour change by offering end users direct and ambient feedback based on their monitored energy consumption and experiences. DEHEMS, as a wide scale domestic energy monitoring and managing system differs from others by enabling real-time and historical electricity monitoring and feedback. However, there is also a requirement to be able to monitor and report domestic gas consumption in order to reason and represent more complete energy feedback information to achieve effect positive behaviour changes. In this paper, we present the gas monitoring system in DEHEMS, that implements automatic retrieval of gas readings. We describe how the system is designed, integrated within the DEHEMS architecture, as well as its implementation and deployment. © 2011 IEEE.

Ma R.,Nanjing University of Information Science and Technology | Sheng L.,Nanjing University | Liu M.,Nanjing Southeast University | Sheng D.N.,California State University, Northridge
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

We numerically study the thermoelectric transport properties based on the Haldane model of the three-dimensional topological insulator (3DTI) thin film in the presence of an exchange field g and a hybridization gap Δ. The thermoelectric coefficients exhibit rich behaviors as a consequence of the interplay between g and Δ in the 3DTI thin film. For Δ=0 but g≠0, the transverse thermoelectric conductivity αxy saturates to a universal value 1.38kBe/h at the center of each Landau level (LL) in the high-temperature regime, and displays a linear temperature dependence at low temperatures. The semiclassical Mott relation is found to remain valid at low temperatures. If g=0 but Δ≠0, the thermoelectric coefficients are consistent with those of a band insulator. For both g≠0 and Δ≠0, αxy saturates to a universal value 0.69kBe/h at the center of each LL in the high-temperature regime. We attribute this behavior to the split of all the LLs, caused by the simultaneous presence of nonzero g and Δ, which lifts the degeneracies between Dirac surface states. © 2013 American Physical Society.

Liu W.,North Carolina State University | Liu W.,National Oceanic and Atmospheric Administration | Liu W.,University of California at San Diego | Liu Z.,Peking University | And 3 more authors.
Climate Dynamics | Year: 2015

Using a generalized stability indicator L, we explore the stability of the Atlantic meridional overturning circulation (AMOC) during the last deglaciation based on a paleoclimate simulation. From the last glacial maximum, as forced by various external climate forcings, notably the meltwater forcing, the AMOC experiences a collapse and a subsequent rapid recovery in the early stage of deglaciation. This change of the AMOC induces an anomalous freshwater divergence and later convergence across the Atlantic and therefore leads to a positive L, suggesting a negative basin-scale salinity advection feedback and, in turn, a mono-stable deglacial AMOC. Further analyses show that most anomalous freshwater is induced by the AMOC via the southern boundary of the Atlantic at 34°S where the freshwater transport (MovS) is about equally controlled by the upper branch of the AMOC and the upper ocean salinity along 34°S. From 19 to 17 ka, as a result of multiple climate feedbacks associated with the AMOC change, the upper ocean at 34°S is largely salinified, which helps to induce a switch in MovS, from import to export. Our study has important implications to the deglacial simulations by climate models. A decomposition of L shows that the AMOC stability is mostly determined by two terms, the salinity stratification at 34°S and the change of stratification with the AMOC. Both terms appear positive in model. However, the former is likely to be distorted towards positive, as associated with a common bias existing over the South Atlantic in climate models. Therefore, the AMOC is potentially biased towards mono-stability in most paleoclimate simulations. © 2014, Springer-Verlag Berlin Heidelberg.

Lu S.,Nanjing University of Information Science and Technology | Lu S.,Anhui Normal University
Nonlinear Analysis: Real World Applications | Year: 2011

The author of this paper studies the existence of local minimum point of functional φ in the first, and then the existence of homoclinic solutions to a p-Laplacian system d/dt[|u′(t)|p-2u′(t)]=∇F(t,u(t))+f(t) is investigated. Under local condition F(t,x)0,ρ>0 and μ>1 are constants, some new results are obtained. © 2010 Published by Elsevier Ltd. All rights reserved.

Liu Q.,Nanjing University of Information Science and Technology
2010 2nd Pacific-Asia Conference on Circuits, Communications and System, PACCS 2010 | Year: 2010

A laterally driven micro machined tunable capacitor is proposed. As an alternative to the traditional designs using two electrodes, three electrodes are used so that the series resistance could be reduced. This design also offers opportunities in the circuit design, since the DC-bias voltage is not applied on the two ports. To achieve the capacitance on the order of 0.4 pF, the electrodes are periodically arranged to form three groups of arrays. Thermal actuator arrays are employed to drive the movable electrodes. In order to simplify the design and fabrication, a structure using two layers to build the electrodes is provided, where the capacitance varies from 0.05 pF to 0.13 pF. This two-layer capacitor has been fabricated using a polysilicon surface micro machining process potentially compatible with CMOS process. © 2010 IEEE.

Li T.,Nanjing University of Information Science and Technology | Zheng W.X.,University of Western Sydney
IEEE Transactions on Circuits and Systems II: Express Briefs | Year: 2012

In this brief, a new criterion for the global asymptotic stability of fixed-point state-space digital filters using generalized saturation arithmetic is presented. Compared with some existing results, a distinct feature of the proposed criterion is that it can include the existing results as special cases or be less restrictive than them. Two examples are given to show this improvement over the existing conditions. © 2012 IEEE.

Wang Z.,Nanjing University of Information Science and Technology | Wang Z.,Nanjing University of Posts and Telecommunications
International Journal of Ad Hoc and Ubiquitous Computing | Year: 2016

The goal of this paper is to design an ID-based encryption (IBE) scheme that can flexibly tolerate leakage bounds, by only increasing the size of secret key proportionally, and the security level can be achieved to be against chosen-ciphertext attacks (CCA). As our main technical tool for CCA security, we introduce an initiation of all-but-one lossy filter, which is a simple version of allbut- many lossy filter to the leakage resilient settings. As our main result, we use the all-but-one lossy filter to construct an IBE scheme that is secure against leakage resilient chosen-ciphertext attacks (CCA), and the leakage rate is 1=2 -o(1). © Copyright 2016 Inderscience Enterprises Ltd.

Luo Q.,Nanjing University of Information Science and Technology | Liao X.X.,Huazhong University of Science and Technology | Zeng Z.G.,Huazhong University of Science and Technology
Science in China, Series F: Information Sciences | Year: 2010

The sufficient and necessary conditions for Lyapunov stability of the zero equilibrium point of Lorenz system are discussed, and some brief criteria are presented for globally exponential stability, globally asymptotical stability and instability. Furthermore, the behavior of the non-zero equilibrium point of Lorenz system is also investigated, and several sufficient and necessary conditions are provided for locally exponential stability and instability. The established theorems in this paper develop and extend the existing achievements on Lyapunov stability of Lorenz system. In conclusion, by applying the obtained results, some less conservative feedback-control laws are derived to guarantee the globally exponential stability of the chaos control of Chen system, Lü system, Yang-Chen system and Yu-Xia Li system. © 2010 Science China Press and Springer-Verlag Berlin Heidelberg.

Ma R.,Nanjing University of Information Science and Technology | Ma R.,California State University, Northridge | Zhu L.,Los Alamos National Laboratory | Sheng L.,Nanjing University | And 2 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

We numerically study the disorder effect on the thermoelectric and thermal transport in bilayer graphene under a strong perpendicular magnetic field. In the unbiased case, we find that the thermoelectric transport has similar properties as in monolayer graphene, i.e., the Nernst signal has a peak at the central Landau level (LL) with a height of the order of kB/e and changes sign near other LLs, while the thermopower has an opposite behavior. We attribute this to the coexistence of particle and hole LLs around the Dirac point. When a finite interlayer bias is applied and a band gap is opened, it is found that the transport properties are consistent with those of a band insulator. We further study the thermal transport from electronic origin and verify the validity of the generalized Weidemann-Franz law. © 2011 American Physical Society.

Vaid B.H.,Nanjing University of Information Science and Technology | Polito P.S.,University of Sao Paulo
Atmosphere - Ocean | Year: 2016

The influence of the biweekly sea surface temperature (SST) in the South China Sea (SCS) on the SCS summer monsoon, especially during the Indian Ocean Dipole (IOD) is presented using the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) SST and rainfall data for April to June from 1999 to 2013. During positive IOD (PIOD) years the biweekly SST anomalies over the SCS lead the rain anomalies by three days, with a significant correlation (r = 0.8, at the 99% confidence level), whereas during negative IOD (NIOD) years, the correlation is only 0.2. The biweekly SST is observed to influence the westward and northward propagating rainfall anomalies over the SCS and, hence, affect the SCS summer monsoon, especially during PIOD years. No such propagation was seen during NIOD years. The biweekly intraseasonal oscillation of SST in the SCS results in enhanced sea level pressure and surface shortwave radiation, especially during PIOD years. The potential findings here indicate that the biweekly SST in the SCS is strongly (weakly) influenced during PIOD (NIOD) years. Further, it is observed that SST in the SCS has a strong (weak) effect on the SCS summer monsoon by westward and northward propagation of rainfall, especially during PIOD (NIOD) years. When a PIOD or NIOD exists over the tropical Indian Ocean, the SCS SST will be strongly (r = 0.6, at the 99% confidence level) or weakly correlated with the residual index, respectively. © 2016 Taylor & Francis

Liu Z.-S.,Nanjing University of Information Science and Technology | Sechovsky V.,Charles University | Divis M.,Charles University
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2013

We have developed a new quantum Monte Carlo approach and utilized it to calculate the magnetic structure, magnetization, and specific heat, etc., of nanoparticles composed of 3d magnetic ions. For comparison, we also performed simulations with the self-consistent computational algorithm which we proposed recently. The calculated results obtained with the two methods are identical, verifying their correctness. We also found that the combination of the two above algorithms can improve the computational efficiency considerably and have more general applicability. © 2012 Elsevier B.V. All rights reserved.

Geyi W.,Nanjing University of Information Science and Technology
IEEE Transactions on Antennas and Propagation | Year: 2013

This paper studies the optimum design of antennas. The objective function to be maximized is the ratio of gain to quality factor (Q) (i.e., the product of gain and bandwidth) in a specified direction. The theoretical upper bounds for the ratio of gain to Q are first rederived by using the IEEE standard definition of antenna Q. The ratio of gain to Q in a specified direction may be considered as a linear functional of the current distribution, and once it is maximized, an eigenvalue equation can be obtained from the variational principle. This eigenvalue equation can then be solved, yielding an optimum current distribution that maximizes the ratio of gain to Q in the specified direction. A number of numerical examples for small antennas have been presented to demonstrate how the theoretical upper bounds for the ratio of gain to Q can be approached by optimizing the current distributions as well as antenna geometries. © 1963-2012 IEEE.

De Cao T.,Nanjing University of Information Science and Technology
Journal of Superconductivity and Novel Magnetism | Year: 2013

The Hubbard model has been investigated widely by many authors, while this work may be new in two aspects. One, we focus on the possible effects of the positions of the gaps associated with the pairing and the spin density wave. Two, we suggest that the models with different parameters are appropriate for different materials (or a material in different doped regions). This will lead to some new insights into the high temperature superconductors. It is shown that the SDW can appear at some temperature region when the on-site Coulomb interaction is larger, while the SC requires a decreased U at a lower temperature. This can qualitatively explain the relationship between superconducting and pseudogap states of Cu-based superconductors in underdoped and optimally doped regions. The superinsulator is also discussed. © 2012 Springer Science+Business Media, LLC.

Liu Z.,Nanjing Southeast University | Chen H.,Nanjing Southeast University | Liu W.,Nanjing University of Information Science and Technology | Xu J.,Nanjing Southeast University | And 2 more authors.
Quantum Information Processing | Year: 2013

From the perspective of quantum circuit, a construction framework and a measurement framework of a general kind of four-qubit states are sketched, respectively. By utilizing the properties of this kind of states, a quantum secure direct communication (QSDC) protocol is put forward, which adopts the idea of optimal quantum superdense coding to achieve a maximal efficiency and high resources capacity. The security of the proposed protocol is discussed in detail and it is proved to be secure theoretically. Moreover, the sufficient and necessary condition of which multipartite states are suitable for optimal quantum superdense coding in quantum secure direct communication is figured out. © 2012 Springer Science+Business Media, LLC.

Yin L.,Nanjing University of Information Science and Technology | Guo L.,Beihang University
International Journal of Systems Science | Year: 2012

This article considers a new tracking control problem for a class of nonlinear stochastic descriptor systems where the tracked target is a given joint probability density function (JPDF). The controlled plants can be represented by multivariate discrete-time descriptor systems with non-Gaussian disturbances and nonlinear output equations. The control objective is to find crisp algorithms such that the conditional output JPDFs can follow the given target JPDF. A direct relationship is established between the JPDFs of the transformed tracking error and the stochastic input. An optimisation approach is presented such that the distances between the output JPDF and the desired one are minimised. Furthermore, a stabilisation suboptimal control strategy is proposed using the linear matrix inequality-based Lyapunov theory. Finally, simulations are provided to demonstrate the effectiveness of the stochastic tracking control algorithms. © 2011 Copyright Taylor and Francis Group, LLC.

Wang X.,Nanjing University of Information Science and Technology
Journal of the Optical Society of Korea | Year: 2014

In a multi-camera measurement system, the determination of the external parameters is one of the vital tasks, referred to as the calibration of the system. In this paper, a new geometrical calibration method, which is based on the theory of the vanishing line, is proposed. Using a planar target with three equally spaced parallel lines, the normal vector of the target plane can be confirmed easily in every camera coordinate system of the measurement system. By moving the target into more than two different positions, the rotation matrix can be determined from related theory, i.e., the expression of the same vector in different coordinate systems. Moreover, the translation matrix can be derived from the known distance between the adjacent parallel lines. In this paper, the main factors effecting the calibration are analyzed. Simulations show that the proposed method achieves robustness and accuracy. Experimental results show that the calibration can reach 1.25 mm with the range about 0.5m. Furthermore, this calibration method also can be used for auto-calibration of the multi-camera measurement system as the feature of parallels exists widely. © 2014, Optical Society of Korea. All rights reserved.

Zhang H.,Nanjing University | Cao L.,Nanjing University | Zhang B.,Nanjing University of Information Science and Technology
Resources, Conservation and Recycling | Year: 2016

Market-based environmental policy can strongly affect both technological advancement and the diffusion of less pollution-intensive or less cost-intensive abatement technologies and facilities. This study applied an agent-based model to examine the effects of an emissions trading system on the NOx technology adoption of power plants in China. The results indicate that an emissions trading system influences obsolete technologies with lower removal levels, but it does not promote the adoption of the most advanced technology. Most power plants will adopt the best available technology under an emissions trading program. In addition, national emissions trading encourages power plants to adopt technologies with relatively higher removal rates compared with separate regional emissions trading systems, but a national program decreases the adoption of most advanced technology. Further, initial allowance allocations based on concentration standards rather than on generation performance standards may promote power plants to adopt the newest technologies more quickly. © 2016 Elsevier B.V.

San Liang X.,Nanjing University of Information Science and Technology | San Liang X.,Central University of Finance and Economics
Entropy | Year: 2014

This paper presents a comprehensive introduction and systematic derivation of the evolutionary equations for absolute entropy H and relative entropy D, some of which exist sporadically in the literature in different forms under different subjects, within the framework of dynamical systems. In general, both H and D are dissipated, and the dissipation bears a form reminiscent of the Fisher information; in the absence of stochasticity, dH=dt is connected to the rate of phase space expansion, and D stays invariant, i.e., the separation of two probability density functions is always conserved. These formulas are validated with linear systems, and put to application with the Lorenz system and a large-dimensional stochastic quasi-geostrophic flow problem. In the Lorenz case, H falls at a constant rate with time, implying that H will eventually become negative, a situation beyond the capability of the commonly used computational technique like coarse-graining and bin counting. For the stochastic flow problem, it is first reduced to a computationally tractable low-dimensional system, using a reduced model approach, and then handled through ensemble prediction. Both the Lorenz system and the stochastic flow system are examples of self-organization in the light of uncertainty reduction. The latter particularly shows that, sometimes stochasticity may actually enhance the self-organization process. © 2014 by the author.

Tan F.,Dalian University of Technology | Sun D.,Dalian University of Technology | Gao J.,Dalian University of Technology | Zhao Q.,Dalian University of Technology | And 4 more authors.
Journal of Hazardous Materials | Year: 2013

In this study, novel molecularly imprinted polymer nanoparticles (nanoMCN@MIPs) were prepared by covalent grafting of ofloxacin-imprinted polymer onto the surface of mesoporous carbon nanoparticles (MCNs). SEM analyses indicated that the prepared nanoMCN@MIPs were almost uniform, and their geometrical mean diameter was about 230. nm. The sorption behaviors of the nanoMCN@MIPs including sorption kinetics and isotherms, effect of pH, ionic strength, and cross-reactivity were investigated in detail. The adsorption capacity of the nanoparticles for ofloxacin was 40.98. mg/g, with a selectivity factor of 2.6 compared to the nonimprinted polymer nanoparticles (nanoMCN@NIPs). The feasibility of removing fluoroquinolone antibiotics (FQs) from environmental waters with the nanoMCN@MIPs was demonstrated using sea water spiked with six typical FQs (ofloxacin, gatifloxacin, balofloxcacin, enrofloxacin, norfloxacin and sarafloxacin). The nanoMCN@MIPs could be reused at least five times with removal efficiency more than 90% except for norfloxacin. © 2012 Elsevier B.V.

Men K.,Nanjing University of Information Science and Technology
Zeitschrift fur Naturforschung - Section A Journal of Physical Sciences | Year: 2011

The northern Xizang Plateau is a main seismic zone inWest China. Since 1700, M ≥ 7 earthquakes have had an obvious commensurability and orderliness in this region. The main ordered values are 106~107a, 77~78a, 53~54a, 26~27a, 11~12a, and 3~4a. According to the information forecasting theory ofWen-BoWeng (W. B. Weng, Fundamentals of Forecasting Theory. Petroleum Industry Press, Beijing 1984 (in Chinese)), combining ordered analysis with complex network technology, we try to explore the practical method for M ≥ 7 earthquake prediction with Chinese characteristics, and build a informational ordered network structure of M ≥ 7 earthquakes in the northern Xizang Plateau. In this paper, we study the prediction of three great earthquakes (the 2001 Kunlunshan M8.1, the 2008Wenchuan M8.0, and the 2010 M7.1 Yushu earthquake) during the beginning of the 21st century based on the method of ordered network structure, and give many famous earthquake examples in China and abroad. Meanwhile, the cause of formation about the Wenchuan and Yushu earthquake has been discussed primarily. At last, we present some new prediction opinions: the future M ≥ 7 earthquakes will happen in 2014 - 2015, 2026 - 2027, and 2030 pre and post in this region. The results show that this method has a unique effect on moderate term and long term prediction for great earthquakes. © 2011 Verlag der Zeitschrift für Naturforschung, Tübingen.

Nguyen T.M.,University of Windsor | Jonathan Wu Q.M.,University of Windsor | Zhang H.,University of Windsor | Zhang H.,Nanjing University of Information Science and Technology
Pattern Recognition | Year: 2014

The generalized Gaussian mixture model (GGMM) provides a flexible and suitable tool for many computer vision and pattern recognition problems. However, generalized Gaussian distribution is unbounded. In many applications, the observed data are digitalized and have bounded support. A new bounded generalized Gaussian mixture model (BGGMM), which includes the Gaussian mixture model (GMM), Laplace mixture model (LMM), and GGMM as special cases, is presented in this paper. We propose an extension of the generalized Gaussian distribution in this paper. This new distribution has a flexibility to fit different shapes of observed data such as non-Gaussian and bounded support data. In order to estimate the model parameters, we propose an alternate approach to minimize the higher bound on the data negative log-likelihood function. We quantify the performance of the BGGMM with simulations and real data. © 2014 Elsevier Ltd.

Liu Z.-S.,Nanjing University of Information Science and Technology | Sechovsky V.,Charles University | Divis M.,Charles University
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2014

The new quantum simulation model and the self-consistent algorithm (SCA) for magnetic nanosystems, that we proposed 2 years ago, were extended to study the magnetic properties of a nanowire consisting of 3d ions which are coupled ferromagnetically. To test the applicability of the algorithm, our simulations in the present work were started from a magnetic structure in which all spins in the whole nanosample were randomly oriented (defined as the random magnetic configuration for later use) as other authors have been doing with Monte Carlo or micromagnetism method, and such calculated results were all reasonable. Especially, the free energies evaluated at the chosen temperatures were found to attenuate spontaneously and quickly, as the program ran, towards the minima according to the principle of lowest free energy as expected. This suggests that the computational algorithm is able to lead the code to converge rapidly to the equilibrium state automatically without the need to minimize the total (free) energy of the system elaborately that must be done if the Monte Carlo or micromagnetism method is used, demonstrating the great power of natural laws. © 2013 Elsevier B.V.

Zhi H.,Nanjing University of Information Science and Technology | Zhang R.-H.,CAS Qingdao Institute of Oceanology | Lin P.,CAS Institute of Atmospheric Physics | Wang L.,Beijing Normal University
Advances in Atmospheric Sciences | Year: 2015

The climatology and interannual variability of sea surface salinity (SSS) and freshwater flux (FWF) in the equatorial Pacific are analyzed and evaluated using simulations from the Beijing Normal University Earth System Model (BNU-ESM). The simulated annual climatology and interannual variations of SSS, FWF, mixed layer depth (MLD), and buoyancy flux agree with those observed in the equatorial Pacific. The relationships among the interannual anomaly fields simulated by BNU-ESM are analyzed to illustrate the climate feedbacks induced by FWF in the tropical Pacific. The largest interannual variations of SSS and FWF are located in the western-central equatorial Pacific. A positive FWF feedback effect on sea surface temperature (SST) in the equatorial Pacific is identified. As a response to El Niño–Southern Oscillation (ENSO), the interannual variation of FWF induces ocean processes which, in turn, enhance ENSO. During El Niño, a positive FWF anomaly in the western-central Pacific (an indication of increased precipitation rates) acts to enhance a negative salinity anomaly and a negative surface ocean density anomaly, leading to stable stratification in the upper ocean. Hence, the vertical mixing and entrainment of subsurface water into the mixed layer are reduced, and the associated El Niño is enhanced. Related to this positive feedback, the simulated FWF bias is clearly reflected in SSS and SST simulations, with a positive FWF perturbation into the ocean corresponding to a low SSS and a small surface ocean density in the western-central equatorial Pacific warm pool. © 2015, Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg.

Tang J.,Anhui University | Shao L.,Nanjing University of Information Science and Technology | Shao L.,University of Sheffield | Zhen X.,University of Sheffield
Pattern Recognition | Year: 2014

Finding correspondences between two related feature point sets is a basic task in computer vision and pattern recognition. In this paper, we present a novel method for point pattern matching via spectral graph analysis. In particular, we aim to render the spectral matching algorithm more robust for positional jitter and outlier. A local structural descriptor, namely the spectral context, is proposed to describe the attribute domain of point sets, which is fundamentally different from the previous methods. Furthermore, the approximate distance order is defined and employed as the metric for geometric consistency of neighboring points in this work. By combining these two novel ingredients, we formulate feature point set matching as an optimization problem with one-to-one constraints. The correspondences are then obtained by maximizing the given objective function via the technique of probabilistic relaxation. Comparative experiments conducted on both synthetic and real data demonstrate the effectiveness of the proposed method, especially in the presence of positional jitter and outliers. © 2013 Elsevier Ltd. All rights reserved.

Sun Y.,CAS Institute of Atmospheric Physics | Wang Z.,CAS Institute of Atmospheric Physics | Dong H.,CAS Institute of Atmospheric Physics | Yang T.,CAS Institute of Atmospheric Physics | And 5 more authors.
Atmospheric Environment | Year: 2012

An Aerodyne Aerosol Chemical Speciation Monitor (ACSM) was first deployed in Beijing, China for characterization of summer organic and inorganic aerosols. The non-refractory submicron aerosol (NR-PM 1) species, i.e., organics, sulfate, nitrate, ammonium, and chloride were measured in situ at a time resolution of ~15 min from 26 June to 28 August, 2011. The total NR-PM 1 measured by the ACSM agrees well with the PM 2.5 measured by a Tapered Element Oscillating Microbalance (TEOM). The average total NR-PM 1 mass for the entire study is 50 ± 30 μg m -3 with the organics being the major fraction, accounting for 40% on average. High concentration and mass fraction of nitrate were frequently observed in summer in Beijing, likely due to the high humidity and excess gaseous ammonia that facilitate the transformation of HNO 3 to ammonium nitrate particles. Nitrate appears to play an important role in leading to the high particulate matter (PM) pollution since its contribution increases significantly as a function of aerosol mass loadings. Positive matrix factorization (PMF) of ACSM organic aerosol (OA) shows that the oxygenated OA (OOA) - a surrogate of secondary OA dominates OA composition throughout the day, on average accounting for 64%, while the hydrocarbon-like OA (HOA) shows a large increase at meal times due to the local cooking emissions. Our results suggest that high PM pollution in Beijing associated with stagnant conditions and southern air masses is characterized by the high contribution of secondary inorganic species and OOA from regional scale, whereas the aerosol particles during the clean events are mainly contributed by the local emissions with organics and HOA being the dominant contribution. © 2012 Elsevier Ltd.

Shao L.,Nanjing University of Information Science and Technology | Shao L.,University of Sheffield | Zhen X.,University of Sheffield | Tao D.,Intelligent Systems Technology, Inc. | Li X.,CAS Xian Institute of Optics and Precision Mechanic
IEEE Transactions on Cybernetics | Year: 2014

We present a novel descriptor, called spatio-temporal Laplacian pyramid coding (STLPC), for holistic representation of human actions. In contrast to sparse representations based on detected local interest points, STLPC regards a video sequence as a whole with spatio-temporal features directly extracted from it, which prevents the loss of information in sparse representations. Through decomposing each sequence into a set of band-pass-filtered components, the proposed pyramid model localizes features residing at different scales, and therefore is able to effectively encode the motion information of actions. To make features further invariant and resistant to distortions as well as noise, a bank of 3-D Gabor filters is applied to each level of the Laplacian pyramid, followed by max pooling within filter bands and over spatio-temporal neighborhoods. Since the convolving and pooling are performed spatio-temporally, the coding model can capture structural and motion information simultaneously and provide an informative representation of actions. The proposed method achieves superb recognition rates on the KTH, the multiview IXMAS, the challenging UCF Sports, and the newly released HMDB51 datasets. It outperforms state of the art methods showing its great potential on action recognition. © 2013 IEEE.

Shao L.,Nanjing University of Information Science and Technology | Yan R.,University of Sheffield | Li X.,CAS Xian Institute of Optics and Precision Mechanic | Liu Y.,Hong Kong Polytechnic University
IEEE Transactions on Cybernetics | Year: 2014

Image denoising is a well explored topic in the field of image processing. In the past several decades, the progress made in image denoising has benefited from the improved modeling of natural images. In this paper, we introduce a new taxonomy based on image representations for a better understanding of state-of-the-art image denoising techniques. Within each category, several representative algorithms are selected for evaluation and comparison. The experimental results are discussed and analyzed to determine the overall advantages and disadvantages of each category. In general, the nonlocal methods within each category produce better denoising results than local ones. In addition, methods based on overcomplete representations using learned dictionaries perform better than others. The comprehensive study in this paper would serve as a good reference and stimulate new research ideas in image denoising. © 2013 IEEE.

Li Z.,University of Maryland University College | Li Z.,CAS Institute of Atmospheric Physics | Li Z.,Nanjing University of Information Science and Technology | Lee K.-H.,University of Maryland University College | And 4 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2010

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. © Copyright 2010 by the American Geophysical Union.

Teng F.,Michigan Technological University | Teng F.,Nanjing University of Information Science and Technology | Santhanagopalan S.,Michigan Technological University | Meng D.D.,Michigan Technological University
Solid State Sciences | Year: 2010

In this work, single-crystalline MnO2 nanoparticles were directly grown on the surface of multi-walled carbon nanotubes (CNTs) homogeneously under in-situ hydrothermal conditions, during which the CNTs were well dispersed in aqueous solution with the aid of dodecyl benzene sulphonic acid sodium (SDBS). This stable suspension ensures the continuous deposition of the MnO2 nanocrystals. It was found that the MnO2/CNTs nanocomposites formed in the presence of CNTs, but the MnO2 nanowires formed without CNTs under the same hydrothermal conditions. Moreover, the as-synthesized MnO2/CNTs sample showed a high specific capacity and cycling stability, which was ascribed to its highly-homogeneous hybrid nanostructure. This homogeneous MnO2/CNTs nanocomposite is shown to be able to take full advantages of both the high capacity of MnO2 and the high electron conductivity of CNTs by integrating them homogeneously. This homogeneous hybrid nanostructure is a promising electrode material for energy storage/conversion devices with excellent performances. © 2010 Elsevier Masson SAS. All rights reserved.

Zhang H.-F.,Nanjing University of Aeronautics and Astronautics | Zhang H.-F.,Nanjing Artillery Academy | Liu S.-B.,Nanjing University of Aeronautics and Astronautics | Yang H.,Nanjing University of Aeronautics and Astronautics | And 2 more authors.
Physics of Plasmas | Year: 2013

In this paper, the magnetooptical effects in dispersive properties for two types of three-dimensional magnetized plasma photonic crystals (MPPCs) containing homogeneous dielectric and magnetized plasma with diamond lattices are theoretically investigated for electromagnetic (EM) wave based on plane wave expansion (PWE) method, as incidence EM wave vector is parallel to the external magnetic field. The equations for two types of MPPCs with diamond lattices (dielectric spheres immersed in magnetized plasma background or vice versa) are theoretically deduced. The influences of dielectric constant, plasma collision frequency, filling factor, the external magnetic field, and plasma frequency on the dispersive properties for both types of structures are studied in detail, respectively, and some corresponding physical explanations are also given. From the numerical results, it has been shown that the photonic band gaps (PBGs) for both types of MPPCs can be manipulated by plasma frequency, filling factor, the external magnetic field, and the relative dielectric constant of dielectric, respectively. Especially, the external magnetic field can enlarge the PBG for type-2 structure (plasma spheres immersed in dielectric background). However, the plasma collision frequency has no effect on the dispersive properties of two types of three-dimensional MPPCs. The locations of flatbands regions for both types of structures cannot be tuned by any parameters except for plasma frequency and the external magnetic field. The analytical results may be informative and of technical use to design the MPPCs devices. © 2013 American Institute of Physics.

Fischer T.,National Climate Center | Fischer T.,Xinjiang Institute of Ecology and Geography | Gemmer M.,National Climate Center | Liu L.,National Climate Center | And 2 more authors.
Climatic Change | Year: 2012

In this paper, change-points in time series of annual extremes in temperature and precipitation in the Zhujiang River Basin are analyzed with the CUSUM test. The data cover the period 1961-2007 for 192 meteorological stations. Annual indicators are analyzed: mean temperature, maximum temperature, warm days, total precipitation, 5-day maximum precipitation, and dry days. Significant change-points (1986/87, 1997/98, 1968/69, and 2003/04) are detected in the time series of most of the indicators. The change-point in 1986/87 is investigated in more detail. Most stations with this change-point in temperature indicators are located in the eastern and coastal areas of the basin. Stations with this change-point in dry days are located in the western area. The means and trends of the temperature indicators increase in the entire basin after 1986/87. The highest magnitudes can be found at the coast and delta. Decreasing (increasing) tendencies in total and 5-day maximum precipitation (dry days) are mostly observed in the western and central regions. The detected change-points can be explained by changes in the indices of the Western Pacific subtropical high and the East Asian summer monsoon as well as by change-points in wind directions. In years when the indices simultaneously increase and decrease (indices taking reverse directions to negative and positive) higher annual temperatures and lower annual precipitation occur in the Zhujiang River Basin. The high station density and data quality are very useful for spatially assessing change-points of climatic extreme events. The relation of the change points to large-scale oscillation can provide valuable data for planning adaptation measures against climate risks, e. g. for flood control, disaster preparedness, and water resource management. © 2011 Springer Science+Business Media B.V.

Zhai J.,CAS Nanjing Institute of Geography and Limnology | Zhai J.,University of Chinese Academy of Sciences | Su B.,National Climate Center | Krysanova V.,Potsdam Institute for Climate Impact Research | And 5 more authors.
Journal of Climate | Year: 2010

Time series of the average annual Palmer drought severity index (PDSI) and standardized precipitation index (SPI) were calculated for 483 meteorological stations in China using monthly data from 1961 to 2005. The time series were analyzed for 10 large regions covering the territory of China and represented by seven river basins and three areas in the southeast, southwest, and northwest. Results show that the frequencies of both dry and wet years for the whole period are lower for southern basins than for the northern ones when estimated by PDSI but very similar for all basins when calculated by SPI. The frequencies of dry and wet years calculated for 5- and 15-yr subperiods by both indices show the upward dry trends for three northeastern basins, Songhuajiang, Liaohe, and Haihe; a downward dry trend for the northwest region; a downward wet trend for the Yellow River basin; and an upward wet trend for the northwest region. Trend detection using PDSI indicates statistically significant negative trends for many stations in the northeastern basins (Songhuajiang, Liaohe, Haihe, and Yellow) and in the middle part of the Yangtze, whereas statistically significant positive trends were found in the mountainous part of the northwest region and for some stations in the upper and lower Yangtze. A moderately high and statistically significant correlation between the percentage of runoff anomaly (PRA) and the annual average PDSI and SPI was found for six large rivers. The results confirm that PDSI and SPI indices can be used to describe the tendency of dryness and wetness severity and for comparison in climate impact assessment. © 2010 American Meteorological Society.

Murakami H.,Meteorological Research Institute | Murakami H.,University of Hawaii at Manoa | Wang B.,University of Hawaii at Manoa | Li T.,University of Hawaii at Manoa | And 2 more authors.
Nature Climate Change | Year: 2013

Projections of the potential impacts of global warming on regional tropical cyclone activity are challenging owing to multiple sources of uncertainty in model physical schemes and different assumptions for future sea surface temperatures. A key factor in projecting climate change is to derive robust signals of future changes in tropical cyclone activity across different model physical schemes and different future patterns in sea surface temperature. A suite of future warming experiments (2075-2099), using a state-of-the-art high-resolution global climate model, robustly predicts an increase in tropical cyclone frequency of occurrence around the Hawaiian Islands. A physically based empirical model analysis reveals that the substantial increase in the likelihood of tropical cyclone frequency is primarily associated with a northwestward shifting of the tropical cyclone track in the open ocean southeast of the islands. Moreover, significant and robust changes in large-scale environmental conditions strengthen in situ tropical cyclone activity in the subtropical central Pacific. These results highlight possible future increases in storm-related socio-economic and ecosystem damage for the Hawaiian Islands. © 2013 Macmillan Publishers Limited. All rights reserved.

Tan S.-C.,CAS Institute of Atmospheric Physics | Tan S.-C.,Nanjing University of Information Science and Technology | Shi G.-Y.,CAS Institute of Atmospheric Physics | Wang H.,Chinese Academy of Meteorological Sciences
Atmospheric Environment | Year: 2012

Analysis of daily observations from 43 meteorological stations in the Inner Mongolia Autonomous Region, China, showed the distribution of spring dust storm events during 2000-2007. Guaizihu and Sunitezuoqi stations had the highest frequencies of dust storms. The interannual and seasonal variations of dust storms were closely related to weather conditions, especially the wind speed. A forward trajectory model and satellite observations were used to investigate the transport paths and dust layers of dust storms from Guaizihu and Sunitezuoqi stations to the China seas and their probability of influencing the seas during spring 2000-2007. Forward trajectories showed that dust storms at Guaizihu and Sunitezuoqi stations had the highest probability of affecting the Yellow Sea, followed by the Bohai Sea, the East China Sea, and the northern South China Sea. The dust particles from Sunitezuoqi station affected these four seas directly through coastal areas, while those from Guaizihu station were transported via the Inner Mongolian deserts and/or the Loess Plateau. The dust storms from Sunitezuoqi station impacting the four seas were characterized by a single dust source and a short transport distance, while those from Guaizihu station were characterized by multiple sources and relatively long transport distances. The dust particles from these two stations were mostly transported in a <4 km layer from the source regions to the seas. The satellite vertical profile also indicated that dust particles were mainly contained in a 0-4 km layer over the source regions and the four seas. An aerosol index retrieved from satellite observations and the estimated dust deposition also supported the influence derived from the forward trajectory model, with large aerosol index and dust deposition values occurring on the dust days affecting the four seas. The average deposition over the four seas was 18.7 g m-2 during spring 2000-2007. © 2011 Elsevier Ltd.

Jeong M.-J.,University of Maryland Baltimore County | Jeong M.-J.,NASA | Li Z.,University of Maryland University College | Li Z.,Nanjing University of Information Science and Technology
Journal of Geophysical Research: Atmospheres | Year: 2010

Aerosol optical thickness (AOT) is one of aerosol parameters that can be measured on a routine basis with reasonable accuracy from Sun-photometric observations at the surface. However, AOT-derived near clouds is fraught with various real effects and artifacts, posing a big challenge for studying aerosol and cloud interactions. Recently, several studies have reported correlations between AOT and cloud cover, pointing to potential cloud contamination and the aerosol humidification effect; however, not many quantitative assessments have been made. In this study, various potential causes of apparent correlations are investigated in order to separate the real effects from the artifacts, using well-maintained observations from the Aerosol Robotic Network, Total Sky Imager, airborne nephelometer, etc., over the Southern Great Plains site operated by the U.S. Department of Energy's Atmospheric Radiation Measurement Program. It was found that aerosol humidification effects can explain about one fourth of the correlation between the cloud cover and AOT. New particle genesis, cloud-processed particles, atmospheric dynamics, and aerosol indirect effects are likely to be contributing to as much as the remaining three fourth of the relationship between cloud cover and AOT. Copyright 2010 by the American Geophysical Union.

Qiu Z.F.,Nanjing University of Information Science and Technology | Doglioli A.M.,Aix - Marseille University | Carlotti F.,Aix - Marseille University
Science China Earth Sciences | Year: 2014

A Lagrangian model is used to evaluate source regions of particles collected in the sediment traps at the DYFAMED (Dynamique des Flux Atmosphériques en Méditerranée) station by tracking particles backwards from March 1 to August 31, 2001. The analysis suggests that source regions depend on the flow fields, the settling speed of the particles, and the deployment depths of the traps. Monthly variation is observed in the distribution patterns of source regions, which is caused by the currents. The source regions are located around the traps and up to hundreds of kilometers away. As the settling speed increases with the particle diameters, the distance to the source regions decreases. The vertical flux can be approximately estimated in 1D for the particles with diameters larger than 500 μm. Furthermore, traps moored at various depths at the DYFAMED can collect particles that originated from different regions in the Ligurian Sea. © 2014, Science China Press and Springer-Verlag Berlin Heidelberg.

Kong Q.,Nanjing University of Information Science and Technology | Qian H.,Nanjing University of Technology
Fire and Materials | Year: 2014

Mg(OH)2 (MH) nanoparticles were synthesized by hydration of the light-burned MgO at low temperature (70°C). Effects of additives, such as magnesium nitrate and magnesium acetate, on the size, morphology and agglomeration of MH particles were investigated. MH nanoparticles have platelet-like structure and approximately 20-40 nm in thicknesses. The supersaturation degree plays an important role in magnesia hydration and is defined. When magnesium acetate was used as the additive, the hydroxyl ion can be homogeneously introduced into the solution. The size and morphology of MH nanoparticles are more homogeneous. Modified by titanate coupling agent, MH nanoparticles were used as the flame retardant for polypropylene (PP). The combustibility, mechanical properties and thermal behaviors of the PP/MH composites were characterized. The mechanical properties of PP/MH composites are not seriously deteriorated with increasing MH content. When the amount of MH fraction reached 65, the limiting oxygen index (LOI) value and UL 94 testing result of MH65 are 33.8 and V-0 grading, respectively. The onset temperature (T10%) and the maximum thermal decomposition temperature (Tmax) of MH65 separately increased by approximately 100°C and 77°C than those of neat PP. Copyright © 2012 John Wiley & Sons, Ltd.

Liu F.,Nanjing University of Information Science and Technology | Wang B.,University of Hawaii at Manoa | Kang I.-S.,Seoul National University
Journal of Climate | Year: 2015

Both observational data analysis and model simulations suggest that convective momentum transport (CMT) by cumulus convection may play a significant role in the intraseasonal oscillations (ISO) by redistributing atmospheric momentum vertically through fast convective mixing process. The authors present a simple theoretical model for the ISO by parameterizing the cumulus momentum transport process in which the CMT tends to produce barotropic wind anomalies that will affect the frictional planetary boundary layer (PBL). In the model with equatorial easterly vertical wind shear (VWS), it is found that the barotropic CMT tends to select most unstable planetary-scale waves because CMT suppresses the equatorial Ekman pumping of short waves, which reduces the shortwave instability from the PBL moisture convergence and accelerates the shortwave propagation. The model with subtropical easterly VWS has behavior that can be qualitatively different from the model with equatorial easterly VWS and has robust northward propagation. The basic mechanism of this northward propagation is that the CMT accelerates the barotropic cyclonic wind to the north of ISO, which will enhance the precipitation by PBL Ekman pumping and favor the northward propagation. The simulated northward propagation is sensitive to the strength and location of the seasonal-mean easterly VWS. These results suggest that accurate simulation of the climatological-mean state is critical for reproducing the realistic ISO in general circulation models. © 2015 American Meteorological Society.

Li T.,Nanjing University of Information Science and Technology | Li T.,University of Western Sydney | Zheng W.X.,University of Western Sydney | Lin C.,Qingdao University
IEEE Transactions on Neural Networks | Year: 2011

By using the fact that the neuron activation functions are sector bounded and nondecreasing, this brief presents a new method, named the delay-slope-dependent method, for stability analysis of a class of recurrent neural networks with time-varying delays. This method includes more information on the slope of neuron activation functions and fewer matrix variables in the constructed Lyapunov-Krasovskii functional. Then some improved delay-dependent stability criteria with less computational burden and conservatism are obtained. Numerical examples are given to illustrate the effectiveness and the benefits of the proposed method. © 2011 IEEE.

Zhou J.,University of Electronic Science and Technology of China | Chen Y.,Beijing Normal University | Zhang X.,University of Electronic Science and Technology of China | Zhan W.,Beijing Normal University | Zhan W.,Nanjing University of Information Science and Technology
International Journal of Remote Sensing | Year: 2013

Examination of the diurnal variations in surface urban heat islands (UHIs) has been hindered by incompatible spatial and temporal resolutions of satellite data. In this study, a diurnal temperature cycle genetic algorithm (DTC-GA) approach was used to generate the hourly 1 km land-surface temperature (LST) by integrating multi-source satellite data. Diurnal variations of the UHI in 'ideal' weather conditions in the city of Beijing were examined. Results show that the DTC-GA approach was applicable for generating the hourly 1 km LSTs. In the summer diurnal cycle, the city experienced a weak UHI effect in the early morning and a significant UHI effect from morning to night. In the diurnal cycles of the other seasons, the city showed transitions between a significant UHI effect and weak UHI or urban heat sink effects. In all diurnal cycles, daytime UHIs varied significantly but night-time UHIs were stable. Heating/cooling rates, surface energy balance, and local land use and land cover contributed to the diurnal variations in UHI. Partial analysis shows that diurnal temperature range had the most significant influence on UHI, while strong negative correlations were found between UHI signature and urban and rural differences in the normalized difference vegetation index, albedo, and normalized difference water index. Different contributions of surface characteristics suggest that various strategies should be used to mitigate the UHI effect in different seasons. © 2013 Copyright Taylor & Francis.

Zhou X.,Nanjing University of Information Science and Technology | Zheng W.,Nanjing Southeast University | Xin M.,Nanjing Southeast University
ISCAS 2012 - 2012 IEEE International Symposium on Circuits and Systems | Year: 2012

In this paper, we propose a novel canonical correlation analysis (CCA) algorithm for facial expression recognition. In contrast to the traditional CCA algorithm, the proposed method is capable of selecting the optimal spectral components of the training data matrix in modelling the linear correlation between the facial feature vectors and the corresponding expression class membership vectors. We formulate this spectral selection problem as a sparse optimization problem, where the 1-norm penalty is adopted to this goal. To recognize the emotion category of each facial image, we present a linear regression formula to predict the emotion class membership for each facial image. The experiments on the JAFFE facial expression database confirm the better recognition performance of the proposed method. © 2012 IEEE.

Li Y.,Nanjing University of Information Science and Technology | Li Y.,Nanjing University | Qin M.,Nanjing University | Cao Y.,Nanjing University | Wang W.,Nanjing University
Science China: Physics, Mechanics and Astronomy | Year: 2014

Hydrogels are a class of special materials that contain a large amount of water and behave like rubber. These materials have found broad applications in tissue engineering, cell culturing, regenerative medicine etc. Recently, the exploration of peptide-based supramolecular hydrogels has greatly expanded the repertoire of hydrogels suitable for biomedical applications. However, the mechanical properties of peptide-based hydrogels are intrinsically weak. Therefore, it is crucial to develop methods that can improve the mechanical stability of such peptide-based hydrogels. In this review, we explore the factors that determine or influence the mechanical stability of peptide-based hydrogels and summarize several key elements that may guide scientists to achieve mechanically improved hydrogels. In addition, we exemplified several methods that have been successfully developed to prepare hydrogels with enhanced mechanical stability. These mechanically strong peptide-based hydrogels may find broad applications as novel biomaterials. It is still challenging to engineer hydrogels in order to mimic the mechanical properties of biological tissues. More hydrogel materials with optimal mechanical properties suitable for various types of biological applications will be available in the near future. © 2014 Science China Press and Springer-Verlag Berlin Heidelberg.

Wang Z.,Nanjing University of Information Science and Technology
Journal of Geophysical Research: Oceans | Year: 2013

We investigate the responses of the Southern Hemisphere subpolar gyres to projected climate changes over the 21st century by Coupled Model Intercomparison Project Phase 3 and 5 models. Under increased greenhouse gas forcing, the Southern Hemisphere westerly winds consistently become intensified, resulting in increased cyclonic wind forcing in the subpolar region in these models. Under such wind forcing changes, it is a robust feature that there are consistent increases in the westward flow close to the coast of Antarctica, with strong implications to the mass balance of the Antarctic ice shelves and ice sheets. However, there are large discrepancies in the responses of the gyre axes and overall gyre strengths. Some models show equatorward expansions of the southern gyre limbs, resulting in consistent and large gyre strength increases, while some other models show poleward contractions of the gyres and generally small and less consistent gyre strength changes. These uncertainties are primarily a result of the uncertain simulations of eddy-driven circulations in the Antarctic Circumpolar Current. The associated buoyancy forcing changes play a secondary role in driving these oceanic responses. This study reveals that there are large uncertainties in the projections of the sub polar circulation in the current generation of coupled climate models, although CMIP5 models have considerably smaller inter-model spreads in the present-day and projected gyre strengths. To predict the subpolar circulation changes, future improved modelling studies need to particularly reduce the uncertainties in the projections of the westerly jet and to reduce the uncertainties in the eddy-driven circulation responses to wind forcing changes. © 2013. American Geophysical Union. All Rights Reserved.

Jiang D.,CAS Institute of Atmospheric Physics | Tian Z.,CAS Institute of Atmospheric Physics | Lang X.,Nanjing University of Information Science and Technology
International Journal of Climatology | Year: 2015

Based on observation and reanalysis data, 77 coupled global climate models (GCMs) participating in the Intergovernmental Panel on Climate Change (IPCC) Third (TAR), Fourth (AR4), and Fifth (AR5) Assessment Reports are evaluated in terms of their ability to simulate the mean state and year-to-year variability of surface air temperature at 2 m and precipitation over China and the climatological East Asian monsoon for the late decades of the 20th century. Results show that GCMs reliably reproduce the geographical distribution of the variables considered. Compared with observations, however, most GCMs have topography-related cold biases (although these are smaller than those found in previous studies), excessive precipitation, an underestimated southeast-northwest precipitation gradient, an overestimated magnitude and spatial variability of the interannual variability of temperature and precipitation, and an inadequate strength of the East Asian monsoon circulation. Pairwise comparison reveals that GCMs continue to improve from the TAR via the AR4 to the AR5 for temperature, but have little change for precipitation and the East Asian monsoon. The ability of GCMs varies with season and is affected to certain degree by their horizontal resolutions. Both the arithmetic mean and the median of multiple GCMs are little affected by filtering GCMs in terms of their ability, and the multi-model mean outperforms most of individual GCMs in every respect. © 2015 Royal Meteorological Society.

Li X.,Zhejiang University | Shen X.,Nanjing University of Information Science and Technology
Journal of the Meteorological Society of Japan | Year: 2013

The rainmicrophysical budget associated with precipitationinthe tropical deep convective regime is investigated through the analysis of grid-scale data from a 1.5-km-mesh two-dimensional cloud-resolving model simulation forced by large-scale forcing from tropical ocean global atmosphere coupled-ocean atmosphere response experiment. The rain grids are partitioned into several types based on the rain microphysical budget, and relationships between rainfall types and vertical profiles of vertical momentum, water vapor, and cloud hydrometeors are examined. Over 67% of the total rainfall is associated with the net rainsource, inwhich the collectionof cloud water by rainis greater thanthe melting of precipitationice to raininthe presence of upward motions throughout the troposphere. Over 26% of the total rainfall is related to downward motions in the lower troposphere, leading to the melting of precipitation ice as a major term in the production of precipitation. About 15% of the total rainfall corresponds to dynamic hydrometeor advectiono ly. © 2013, Meteorological Society of Japan.

Ma R.,Nanjing University of Information Science and Technology
International Journal of Modern Physics B | Year: 2013

We numerically study the thermoelectric transport properties in trilayer graphene in the presence of a strong perpendicular magnetic field and disorder. In the unbiased case, we find that the thermoelectric transport has similar properties as in monolayer graphene. In the high temperature regime, the transverse thermoelectric conductivity αxy saturates to a universal value 8.31 kBe/h at the center of each Landau level (LL), and displays a linear temperature dependence at low temperatures. The Nernst signal has a peak at the central LL with a height of the order of k B/e, while the thermopower changes sign. We attribute this to the coexistence of particle and hole LLs around the Dirac point. When a finite interlayer bias is applied and a band gap is opened, it is found that the transport properties are consistent with those of a band insulator. © 2013 World Scientific Publishing Company.

Sun Y.L.,CAS Institute of Atmospheric Physics | Wang Z.F.,CAS Institute of Atmospheric Physics | Fu P.Q.,CAS Institute of Atmospheric Physics | Yang T.,CAS Institute of Atmospheric Physics | And 5 more authors.
Atmospheric Chemistry and Physics | Year: 2013

Air pollution is a major environmental concern during all seasons in the megacity of Beijing, China. Here we present the results from a winter study that was conducted from 21 November 2011 to 20 January 2012 with an Aerodyne Aerosol Chemical Speciation Monitor (ACSM) and various collocated instruments. The non-refractory submicron aerosol (NR-PM1) species vary dramatically with clean periods and pollution episodes alternating frequently. Compared to summer, wintertime submicron aerosols show much enhanced organics and chloride, which on average account for 52% and 5 %, respectively, of the total NR-PM1 mass. All NR-PM1 species show quite different diurnal behaviors between summer and winter. For example, the wintertime nitrate presents a gradual increase during daytime and correlates well with secondary organic aerosol (OA), indicating a dominant role of photochemical production over gas-particle partitioning. Positive matrix factorization was performed on ACSM OA mass spectra, and identified three primary OA (POA) factors, i.e., hydrocarbon-like OA (HOA), cooking OA (COA), and coal combustion OA (CCOA), and one secondary factor, i.e., oxygenated OA (OOA). The POA dominates OA during wintertime, contributing 69 %, with the other 31% being SOA. Further, all POA components show pronounced diurnal cycles with the highest concentrations occurring at nighttime. CCOA is the largest primary source during the heating season, on average accounting for 33% of OA and 17%of NR-PM1. CCOA also plays a significant role in chemically resolved particulate matter (PM) pollution as its mass contribution increases linearly as a function of NRPM 1 mass loadings. The SOA, however, presents a reverse trend, which might indicate the limited SOA formation during high PM pollution episodes in winter. The effects of meteorology on PM pollution and aerosol processing were also explored. In particular, the sulfate mass is largely enhanced during periods with high humidity because of fog processing of high concentration of precursor SO2. In addition, the increased traffic-related HOA emission at low temperature is also highlighted. © Author(s) 2013.

Xia M.,Nanjing University of Information Science and Technology | Xia M.,Donghua University | Xia M.,Hong Kong Polytechnic University | Wang Z.,Donghua University | Fang J.,Donghua University
Neurocomputing | Year: 2011

Temporal information processing, for instance the temporal association, plays an important role on many functions of brain. Among the various dynamics of neural networks, dynamic depression synapses and chaotic behavior have been regarded as the intriguing characteristics of biological neurons. In this paper, temporal association based on dynamic synapses and chaotic neurons is proposed. Interestingly, by introducing dynamic synapses into a temporal association, we found that the sequence storage capacity can be enlarged, that the transition time between patterns in the sequence can be shortened, and that the stability of the sequence can be enhanced. For particular interest, owing to chaotic neurons, the steady-state period becomes shorter in the temporal association and it can be adjusted by changing the parameter values of chaotic neurons. Simulation results demonstrating the performance of the temporal association are presented. © 2011 Elsevier B.V.

Chen B.,Nanjing University | Yang J.,Nanjing University of Information Science and Technology | Pu J.,PLA University of Science and Technology
Journal of the Meteorological Society of Japan | Year: 2013

Characteristics of raindrop size distribution (DSD) during the Meiyu season are studied using ground-based disdrometer measurements carried out in eastern China (Nanjing) from 2009 to 2011. The observational spectra are divided into convective and stratiform types. The results show that the histograms of the logarithm of the generalized intercept parameter (log10NW) and mass-weighted mean diameter of raindrops (Dm) are negatively and positively skewed, respectively, for both convective and stratiform rain. The absolute value of the skewness coefficient is higher for convectiverain than for stratiform rain, in particular for thelog 10NW distribution. Theme an log10NW and Dm values are 3.80 and 1.71 mm for convective rain and 3.45 and 1.30 mm for stratiform rain, respectively. The shape (μ) - slope (Λ) relationship of the gamma distribution and the radar reflectivity (Z) - rain rate (R) relationship are also derived for convective rain. The Z{combining long stroke overlay}R relationship is found to be Z = 368R1.21. The interpretation of the statistical parameters obtained in this study and possible mechanisms that yield difference and similarity in comparison with those in previous studies are discussed. ©2013, Meteorological Society of Japan.

Ding H.,Nanjing University of Information Science and Technology | Shi W.,Hong Kong Polytechnic University
International Journal of Remote Sensing | Year: 2013

Rapid global economic development has resulted in a corresponding intensification of urbanization, which has in turn impacted the ecology of vast regions of the world. A series of problems have thus been introduced, such as changes in land-use/land-cover (LULC) and changes in local climate. The process of urbanization predominantly represents changes in land-use, and is deemed by researchers to be the chief cause of climate change and ecological change. One of the principal purposes of the research in this field is to find ways to mitigate the influence of land-use change on local or global environments. In the study presented in this article, satellite images were utilized to extract information regarding land-use in Beijing City, and to develop maps of land surface temperature (LST) during two different periods of time: 2 August 1999 and 8 August 2010. A supervised classification scheme, a support vector machine, was used to derive the land-use change map for the above periods. Maps of surface temperature are derived from the thermal band of Landsat images using the mono-window algorithm. Results from post-classification comparison indicated that an increase in impervious surface areas was found to be dramatic, while the area of farmland decreased rapidly. The changes in LULC were found to have led to a variation in surface temperature, as well as a spatial distribution pattern of the urban heat island phenomenon. This research revealed that the hotspots were mainly located in areas dominated by three kinds of material: bare soil, rooftops, and marble surfaces. Results from the local Moran's I index indicated that the use of lower surface temperature materials will help to mitigate the influence of the urban heat island phenomenon. The results of this research study provide a reference for government departments involved in the process of designing residential regions. Such a reference should enable the development of areas sympathetic to environmental changes and hence mitigate the effects of the growing intensity of urbanization. © 2013 Copyright 2013 Taylor & Francis.

Wang J.,Nanjing University | Luo W.,Nanjing University | Feng J.,Nanjing University | Zhang L.,Nanjing University | And 3 more authors.
Physical Chemistry Chemical Physics | Year: 2013

Water adsorption and dissociation on the perfect, oxygen containing and nitrogen vacancy containing Ta3N5(100) surfaces are systematically studied by density functional theory calculations. The results show that the perfect Ta3N5(100) surface is very active for water dissociation because of the dangling bonds formed on the perfect Ta3N5(100) surface. The presence of oxygen on the surface is able to stabilize the Ta3N5(100) surface but not to facilitate water dissociation, which may be ascribed to the saturation of surface dangling bonds by oxygen. The presence of a nitrogen vacancy on the surface is able to facilitate water dissociation, but Ta3N 5(100) surfaces with nitrogen vacancies are not stable. We found that keeping the impurity oxygen as less as possible is one effective approach to enhance the water splitting ability of Ta3N5. We propose that doping with foreign elements is one potential method to obtain a clean Ta3N5(100) surface, since the oxygen concentration may be adjusted by competition between oxygen and foreign elements. © 2013 The Owner Societies.

Zhong K.,Nanjing University of Information Science and Technology
Spectroscopy Letters | Year: 2013

ZnO quantum dots (QDs) embedded in SiO2 matrix are fabricated by ion implantation and annealing treatment methods. When the Zn-doping dose is (2, 3, 5, and 7) × 1016 cm-2, the size of quantum dots is in the range of ∼4-10 nm in diameter according to the XRD and HR-TEM results. Ultraviolet and green light emissions from the specimen are obtained at room temperature. With the increase of the Zn-doping dose, the PL peak in the ultraviolet region red shifts from 3.32 to 3.10 eV. This PL peak is related to the size of ZnO QDs, which is ascribed to the free exciton recombination in QDs. The green light emissions centered at 2.43 and 2.25 eV are independent of the Zn-doping dose and annealing temperature, which are attributed to the deep-level defect and the small peroxy radical (SPR) defect, respectively. © 2013 Copyright Taylor and Francis Group, LLC.

Ren G.,National Climate Center | Guan Z.,Nanjing University of Information Science and Technology | Shao X.,CAS Institute of Geographical Sciences and Natural Resources Research | Gong D.Y.,Beijing Normal University
Climate Research | Year: 2011

This Climate Research Special includes 10 studies reporting recent findings on change in climatic extremes in mainland China, including its characteristics, possible causes and impacts. This preface provides a summary of research results and their implications for detecting, projecting and adapting to regional climate change. © Inter-Research 2011.

Bin C.,Chinese Academy of Meteorological Sciences | Xiang-De X.,Chinese Academy of Meteorological Sciences | Tianliang Z.,Nanjing University of Information Science and Technology
International Journal of Climatology | Year: 2013

This study presented a quantitative climatology of atmospheric moisture affecting the Yangtze River Basin (YRB) region in boreal summer season, as well as the spatial evolution of atmospheric moisture passage towards the target regions. A three-dimensional Lagrangian particle dispersion model FLEXPART was driven by the National Centers for Environmental Prediction Final Operational Global Analysis data combined with a backtracking scheme, and the transport contributions to the moisture budget over the YRB region was identified through the continuous calculation of changes in specific humidity along the FLEXPART back trajectories of all air masses residing over this region for a period of six summers of year 2004-2009. The back trajectory analysis revealed four major moisture sources contributed to the YRB summer water vapour with different transport timescales: the East China Sea (17.5%), South China Sea (26.6%), Indian peninsula and the Bay of Bengal (20.5%) and Arabian Sea (13.6%). The properties of moisture sources and its transport processes are dominated by the Asian Summer Monsoon regimes. The Tibetan Plateau also acts as an effective barrier for the meridional moisture transport, leading to distinct moisture sinks at the southern slope. In contrast to the previous results, the tropical western Pacific only plays a minor role in the water vapour contributors. The importance of the four source areas varies over the summer: East and South China Sea sources persist throughout the summer, whereas the Indian peninsula, the Bay of Bengal and Arabian Sea sources reach the strongest moisture supply to the YRB region only in high summer (July), showing a close association with the March of Asian monsoon. The further evaluation shows that the inter-annual variability of precipitation over YRB is strongly related to the moisture sources in the Bay of Bengal and Arabian Sea. © 2012 Royal Meteorological Society.

Zhang R.,Beihang University | Li T.,Nanjing University of Information Science and Technology | Guo L.,Beihang University
Mathematical Problems in Engineering | Year: 2013

This paper is concerned with H∞ control problem for flexible spacecraft with disturbance and time-varying control input delay. By constructing an augmented Lyapunov functional with slack variables, a new delay-dependent state feedback controller is obtained in terms of linear inequality matrix. These slack variables can make the design more flexible, and the resultant design also can guarantee the asymptotic stability and H∞ attenuation level of closed-loop system. The effectiveness of the proposed design method is illustrated via a numerical example. © 2013 Ran Zhang et al.

Chen Y.,Nanjing University of Information Science and Technology | Zhai P.,Chinese Academy of Meteorological Sciences | Li L.,Chinese Academy of Meteorological Sciences
International Journal of Climatology | Year: 2016

The East Asia/Pacific (EAP) teleconnection can substantially modulate weather anomalies over eastern Asia during summer. Wavelet analyses, including ensemble mean power spectrum and accumulated frequency of significant components, highlight 10-30-day oscillations in the EAP index. The influences of these low-frequency oscillations on weather anomalies are further investigated via both phase-dependent and lead-lag composites. On 10-30-day scales, a tripole structure of precipitation anomalies and a temperature seesaw form concurrently over adjacent regions along eastern Asia. These anomalies last for about 1week, constituting anomalous weather spells with possible extreme values around the peak/valley phases. For cold spells over Northeast Asia during positive phases, the low-frequency easterly is the determinant factor. On one hand, it advects cold air from the sea east of the land. On the other hand, it conveys moisture to form low-based clouds, which are effective in inhibiting incoming solar radiation. While, for cold spells over central-eastern Siberia during negative phases, regional-scale precipitation and cold advections conveyed by anomalous northerlies combine to make contributions. Both hot spells over central-eastern Siberia/Northeast Asia during positive/negative phases mainly result from the adiabatic heating and increasing solar radiation, both of which are attributed to strong descent in response to upper-level convergences. In addition to great intensity, the high-impact property of these simultaneous weather anomalies also arises from their long duration and large spatial extent. By taking advantages of the quasi-periodicity of the 10-30-day oscillations, better predictions of these simultaneous weather anomalies/extremes would be anticipated. © 2016 Royal Meteorological Society.

Mubeen S.,University of California at Riverside | Lai M.,Nanjing University of Information Science and Technology | Zhang T.,CAS Suzhou Institute of Nano Technology and Nano Bionics | Lim J.-H.,University of California at Riverside | And 3 more authors.
Electrochimica Acta | Year: 2013

A facile electrochemical functionalization method was utilized to decorate single-walled carbon nanotubes (SWNTs) with tin oxide and their gas sensing performance toward various analytes (NH3, NO2, H 2, H2S, acetone, and water vapor) was evaluated at room temperature. Tin oxy-hydroxide was site-specifically precipitated on the surface of SWNTs because of an increase in local pH during electrochemical reduction of nitrate to nitrite ions. By adjusting the amount of charge passed during deposition, the amount of tin oxide deposited on SWNTs was controlled, which altered the electronic and gas sensing properties of the nanostructures. The resulting hybrid nanostructures showed excellent sensitivities upon exposure to trace amounts of both oxidizing gases (limit of detection (LOD) of 25 ppb V for NO2) and reducing gases (LOD of 10 ppmV for H2) at room temperature. The enhanced sensing performance was due to the charge transfer between the surface active tin oxide nanoparticles and SWNTs, with the direction of charge transfer depending on the analyte gas. This approach can be applied to fabricate other hybrid metal oxide-SWNTs nanostructures to create highly sensitive gas sensor arrays. © 2013 Elsevier Ltd.

Kou L.,Nanjing University of Information Science and Technology | Wang X.,CAS Institute of Electronics | Xiang M.,CAS Institute of Electronics | Zhu M.,CAS Institute of Electronics
IEEE Transactions on Aerospace and Electronic Systems | Year: 2012

Circular synthetic aperture radar (SAR) imaging on the geosynchronous orbit is an innovative SAR imaging mode, which can produce high-resolution three-dimensional (3D) images and offer 24-h continuous surveillance of a broad area. In this paper, we use the geosynchronous circular synthetic aperture radar (GEOCSAR) to efficiently produce high-resolution 3D surface displacement maps by repeat pass interferometry. The coverage areas with GEOCSAR imaging can be mapped from different view directions; thus, a 3D displacement can be provided daily. First, we derive the connection between the GEOCSAR interferometric phase and the surface deformation for analytically interpreting its capability to resolve the three components of the deformation. Then, to retrieve the three components of the deformation, a retrieval matrix is deduced. Furthermore, analyses of the errors in the observation phase vector and retrieval matrix are described, and the way these errors propagate into the deformation vector is modeled. To reduce the errors of the deformation measurement, the retrieval matrix is optimized by choosing appropriate parameters and making the condition number of the matrix minimal. Finally, the simulation results validate the correctness of the analysis, and the 3D retrieval deformation is presented with three subapertures and shows an improvement of accuracy when the optimal retrieval matrix is used. © 1965-2011 IEEE.

Zhang B.,Nanjing University of Information Science and Technology | Perrie W.,Bedford Institute of Oceanography
International Journal of Remote Sensing | Year: 2014

Synthetic aperture radar (SAR) is a useful instrument for monitoring typhoons, hurricanes, and tropical cyclones from space. In this article, we summarize high wind-speed retrieval and validation methods for multi-polarization SAR. Compared to co-polarized geophysical model functions, we show that a cross-polarized wind-speed retrieval model is potentially able to estimate wind speed under extreme weather conditions. The resulting wind speeds are validated using in situ buoy observations, and airborne Stepped-Frequency Microwave Radiometer (SFMR) and spaceborne scatterometer measurements, as well as the National Oceanic and Atmospheric Administration (NOAA) Hurricane Research Division's Hurricane Wind Analysis System (H*Wind) data. We also analyse the effect of intense rainfall on SAR-derived winds. The wind-speed retrieval accuracy can be improved in cases where the normalized radar cross sections (NRCSs) are suitably modified in rainfall areas. © 2014 Taylor & Francis.

Zhou B.,National Climate Center | Zhou B.,Nanjing University of Information Science and Technology | Wen Q.H.,Environment Canada | Xu Y.,National Climate Center | And 2 more authors.
Journal of Climate | Year: 2014

This paper presents projected changes in temperature and precipitation extremes in China by the end of the twenty-first century based on the Coupled Model Intercomparison Project phase 5 (CMIP5) simulations. The temporal changes and their spatial patterns in the Expert Team on Climate Change Detection and Indices (ETCCDI) indices under the RCP4.5 and RCP8.5 emission scenarios are analyzed. Compared to the reference period 1986-2005, substantial changes are projected in temperature and precipitation extremes under both emission scenarios. These changes include a decrease in cold extremes, an increase in warm extremes, and an intensification of precipitation extremes. The intermodel spread in the projection increases with time, with wider spread under RCP8.5 than RCP4.5 for most indices, especially at the subregional scale. The difference in the projected changes under the two RCPs begins to emerge in the 2040s. Analyses based on the mixed-effects analysis of variance (ANOVA) model indicate that by the end of the twenty-first century, at the national scale, the dominant contributor to the projection uncertainty of most temperature-based indices, and some precipitation extremes [including maximum 1-day precipitation (RX1day) and maximum 5-day precipitation (RX5day), and total extremely wet day total amount (R95p)], is the difference in emission scenarios. By the end of the twenty-first century, model uncertainty is the dominant factor at the regional scale and for the other indices. Natural variability can also play very important role. © 2014 American Meteorological Society.

Liu Z.-S.,Nanjing University of Information Science and Technology | Sechovsky V.,Charles University | Divis M.,Charles University
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2014

Two new quantum simulation methods, which we developed recently based on the Metropolis and self-consistent algorithms defined as QMC and SCA approaches respectively, were employed to investigate the magnetic properties of an antiferromagnetic nanoparticle with strong surface anisotropy. All simulations were started from a random magnetic configuration and carried out from a temperature well above the phase transition stepwise down to very low temperatures as other researchers have been doing in classical Monte Carlo (CMC) simulations. It turns out that the magnetic structures, magnetizations, total (free) energy, magnetic entropy and specific heat calculated by means of the two approaches are well consistent with each other, thereby verifying their correctness mutually. © 2014 Elsevier B.V.

Li Y.,Nanjing University of Information Science and Technology | Sun Y.,Nanjing University | Qin M.,Nanjing University | Cao Y.,Nanjing University | Wang W.,Nanjing University
Nanoscale | Year: 2015

The rigidity of peptide fibers is essential for their chemical and biological functions, despite that it remains largely unexplored. Here, we present the first direct measurement of the mechanics of individual fibers in peptide hydrogels by AFM imaging and statistical analysis and find that the intermolecular interactions play a considerable role. This journal is © The Royal Society of Chemistry.

He W.,National Climate Center China Meteorological Administration Beijing China | Zhao S.,National Climate Center China Meteorological Administration Beijing China | Liu Q.,Nanjing University of Information Science and Technology | Jiang Y.,National Climate Center China Meteorological Administration Beijing China
International Journal of Climatology | Year: 2015

In this study, the detrended fluctuation analysis (DFA) method is used to analyse the drought and flood index (DFI) of the past 531 years in 20 stations over east central China. It is found that the variation of the DFI exhibits long-range correlation. The long-range correlation gradually decreases from northwest to southeast over the studied region. Moreover, the recurrence times of droughts or floods also show long-range correlation. The long-range correlation in the DFI data will disappear if the DFI data are randomly shuffled, which was also found in the recurrence time of the randomly shuffled DFI series for each station. The results show that long-range correlation is an intrinsic property of drought or flood events, which could result in the long-range correlation of the corresponding recurrence times. At present, the prediction skill of droughts/floods in Asian-Australian monsoon region is relatively low, particularly in most of China. The long-range correlation of the DFI provides a theoretical basis for climate predictions of droughts/floods and may help improve model performance by amending the model configuration, in terms of addressing parameterization problems and improving atmosphere-ocean coupling. © 2015 Royal Meteorological Society.

Hsu P.-C.,Nanjing University of Information Science and Technology | Lee J.-Y.,Pusan National University | Ha K.-J.,Pusan National University
International Journal of Climatology | Year: 2015

How boreal summer intraseasonal oscillation (BSISO) modulates the probability and spatial distributions of extreme rainfall occurrence over populous southern China was examined, using the newly proposed BSISO indices and two high-resolution rain-gauge-based rainfall datasets in China. The probability density function of May-August rainfall in southern China is skewed towards large values in phases 2-4 of the first component and in phases 5-7 of the second component of BSISO life cycle, during which the probability of extreme rainfall events at the 75th (90th) percentile increases by 30-50% (over 60%) relative to the non-BSISO period. The devastating floods with prolonged extreme rainfall in southern China over the three past decades occurred coincidently with these BSISO phases. The first component of BSISO, associated with 30-60-day eastward/northeastward-propagating ISO, is more favourable for the rainfall extreme over in-land China. In contrast, the second component of BSISO, related to the 10-30-day northwestward propagating ISO, tends to link with the rainfall extreme along the southeast coast of South China. Moisture budget indicates that the favourable environment for rainfall extreme is associated with southwesterly moisture convergence over southern China, while the moisture advection contributes insignificantly. This study suggests a potential for monitoring and probabilistic prediction of extreme rainfall events in southern China based on the real-time BSISO indices. © 2015 Royal Meteorological Society.

Dong Y.H.,Nanjing University of Information Science and Technology
Applied Mechanics and Materials | Year: 2014

In this paper, we study a risk model in which the claim sizes are extended negatively dependent random variables with consistently varying tails, and the arrival of the successive insurance policies forms a nonstandard renewal processes. For this risk model, we give the precise large deviation of the claim surplus process. © (2014) Trans Tech Publications, Switzerland.

Li P.,Nanjing University of Information Science and Technology | Zhang T.,CAS Nanjing Institute of Soil Science | Wang X.,CAS Nanjing Institute of Soil Science | Yu D.,CAS Nanjing Institute of Soil Science
Soil and Tillage Research | Year: 2012

The hilly red soil region of subtropical China is a major rice producing area, where over-exploitation and non-agricultural uses of paddy soils have decreased soil quality and rice productivity. Our objectives were to develop and evaluate a soil quality assessment protocol for Yujiang County in Jiangxi Province. A variety of soil samples, representing the spatial homogeneity in 114 paddy fields, were collected and analyzed for several chemical and physical properties. Pearson correlation analysis between rice yield and the various soil properties was used to identify potential soil quality indicators. Principal component analysis (PCA) was then used to group the indicators into appropriate soil quality factors. A minimum data set (MDS) including soil organic matter, available nitrogen, available phosphorus, slowly available potassium and sand content accounted for 77.9% of the quality variation among soils. A soil quality index (SQI) was calculated using the Integrated Quality Index (IQI) equation. Significant correlation between the SQI and rice yield indicated the index had high biological significance for Jiangxi province and other paddy areas with similar soils. © 2012 Elsevier B.V.

Yin Z.,CAS Institute of Atmospheric Physics | Wang H.,Nanjing University of Information Science and Technology
International Journal of Climatology | Year: 2015

Haze is a serious issue in China today, presenting a substantial pollution problem to the public. To enhance understanding of haze mechanisms in recent years, this study examined the relationship between the subtropical western Pacific sea surface temperature (SST) and the haze pollution over North-Central North China Plain. The empirical orthogonal function result showed an opposite trend of boreal winter (December-January-February) haze days (WHD) between the south and north of the Huaihe River. The negative sea surface temperature anomaly (SSTA) over the subtropical western Pacific could intensify the WHD over North-Central North China Plain. As an effective external forcing, the preceding boreal autumn (Sepember-October-November) negative SSTA could weaken the East Asian winter monsoon (EAWM) circulation, leading to conditions such as a weaker Siberian High, reduced wind speed, higher humidity and an abnormal southerly wind. These conditions provide a favourable environment for haze with static stability and potential for hygroscopic growth. A series of SST sensitivity experiments were carried out using version 3.1 of the Community Atmosphere Model. When negative SSTA with different strengths were added into the model, all the key factors exhibited favourable features for haze, such as smaller EAWM index, stronger inversion potential, weaker vertical velocity, lower boundary layer height and higher relative humidity. © 2015 Royal Meteorological Society.

Tian X.,CAS Institute of Atmospheric Physics | Tian X.,Nanjing University of Information Science and Technology | Xie Z.,CAS Institute of Atmospheric Physics | Liu Y.,CAS Institute of Atmospheric Physics | And 4 more authors.
Atmospheric Chemistry and Physics | Year: 2014

We have developed a novel framework ("Tan-Tracker") for assimilating observations of atmospheric CO2 concentrations, based on the POD-based (proper orthogonal decomposition) ensemble four-dimensional variational data assimilation method (PODEn4DVar). The high flexibility and the high computational efficiency of the PODEn4DVar approach allow us to include both the atmospheric CO2 concentrations and the surface CO2 fluxes as part of the large state vector to be simultaneously estimated from assimilation of atmospheric CO2 observations. Compared to most modern top-down flux inversion approaches, where only surface fluxes are considered as control variables, one major advantage of our joint data assimilation system is that, in principle, no assumption on perfect transport models is needed. In addition, the possibility for Tan-Tracker to use a complete dynamic model to consistently describe the time evolution of CO2 surface fluxes (CFs) and the atmospheric CO2 concentrations represents a better use of observation information for recycling the analyses at each assimilation step in order to improve the forecasts for the following assimilations. An experimental Tan-Tracker system has been built based on a complete augmented dynamical model, where (1) the surface atmosphere CO2 exchanges are prescribed by using a persistent forecasting model for the scaling factors of the first-guess net CO2 surface fluxes and (2) the atmospheric CO2 transport is simulated by using the GEOS-Chem three-dimensional global chemistry transport model. Observing system simulation experiments (OSSEs) for assimilating synthetic in situ observations of surface CO2 concentrations are carefully designed to evaluate the effectiveness of the Tan-Tracker system. In particular, detailed comparisons are made with its simplified version (referred to as TT-S) with only CFs taken as the prognostic variables. It is found that our Tan-Tracker system is capable of outperforming TT-S with higher assimilation precision for both CO2 concentrations and CO2 fluxes, mainly due to the simultaneous estimation of CO2 concentrations and CFs in our Tan-Tracker data assimilation system. A experiment for assimilating the real dry-air column CO2 retrievals (X CO2) from the Japanese Greenhouse Gases Observation Satellite (GOSAT) further demonstrates its potential wide applications. © Author(s) 2014.

Zhang J.,National Oceanic and Atmospheric Administration | Qi Y.,National Oceanic and Atmospheric Administration | Qi Y.,Nanjing University of Information Science and Technology | Qi Y.,University of Oklahoma | And 3 more authors.
Journal of Hydrometeorology | Year: 2012

This study explores error sources of the National Weather Service operational radar-based quantitative precipitation estimation (QPE) during the cool season over the complex terrain of the western United States. A new, operationally geared radar QPE was developed and tested using data from the National Oceanic and Atmospheric Administration Hydrometeorology Testbed executed during the 2005/06 cool season in Northern California. The new radar QPE scheme includes multiple steps for removing nonprecipitation echoes, constructing a seamless hybrid scan reflectivity field, applying vertical profile of reflectivity (VPR) corrections to the reflectivity, and converting the reflectivity into precipitation rates using adaptive Z-R relationships. Specific issues in radar rainfall accumulations were addressed, which include wind farm contaminations, blockage artifacts, and discontinuities due to radar overshooting. The new radar QPE was tested in a 6-month period of the 2005/06 cool season and showed significant improvements over the current operational radar QPE (43% reduction in bias and 30% reduction in root-mean-square error) when compared with gauges. In addition, the new technique minimizes various radar artifacts and produces a spatially continuous rainfall product. Such continuity is important for accurate hydrological model predictions. The new technique is computationally efficient and can be easily transitioned into operations. One of the largest remaining challenges is obtaining accurate radar QPE over the windward slopes of significant mountain ranges, where low-level orographic enhancement of precipitation is not resolved by the operational radars leading to underestimation. Additional high-resolution and near-surface radar observations are necessary for more accurate radar QPE over these regions. © 2012 American Meteorological Society.

Zheng B.-C.,Nanjing University of Information Science and Technology | Yang G.-H.,Northeastern University China
ISA Transactions | Year: 2013

In this paper, an H2 control design for linear uncertain systems with input quantization in the presence of more general encoder/decoder mismatch is investigated. The construction of the control law includes two parts: linear part and nonlinear part. The gain of the linear part is derived from linear matrix inequalities (LMIs), and the linear part of the control law is designed for achieving the H2 performance against system characteristic matrix uncertainty and encoder/decoder mismatch. The nonlinear part is designed to eliminate the influence of external disturbance and quantization error. Finally, examples are provided to illustrate the effectiveness of the proposed method. © 2013 ISA.

Meijers A.J.S.,British Antarctic Survey | Shuckburgh E.,British Antarctic Survey | Bruneau N.,British Antarctic Survey | Sallee J.-B.,British Antarctic Survey | And 2 more authors.
Journal of Geophysical Research: Oceans | Year: 2012

The representation of the Antarctic Circumpolar Current (ACC) in the fifth Coupled Models Intercomparison Project (CMIP5) is generally improved over CMIP3. The range of modeled transports in the historical (1976-2006) scenario is reduced (90-264 Sv) compared with CMIP3 (33-337 Sv) with a mean of 15551 Sv. The large intermodel range is associated with significant differences in the ACC density structure. The ACC position is accurately represented at most longitudes, with a small (1.27) standard deviation in mean latitude. The westerly wind jet driving the ACC is biased too strong and too far north on average. Unlike CMIP3 there is no correlation between modeled ACC latitude and the position of the westerly wind jet. Under future climate forcing scenarios (2070-2099 mean) the modeled ACC transport changes by between -26 to +17 Sv and the ACC shifts polewards (equatorwards) in models where the transport increases (decreases). There is no significant correlation between the ACC position change and that of the westerly wind jet, which shifts polewards and strengthens. The subtropical gyres strengthen and expand southwards, while the change in subpolar gyre area varies between models. An increase in subpolar gyre area corresponds with a decreases in ACC transport and an equatorward shift in the ACC position, and vice versa for a contraction of the gyre area. There is a general decrease in density in the upper 1000 m, particularly equatorwards of the ACC core. © 2012. American Geophysical Union. All Rights Reserved.

Shen Y.,Nanjing University of Information Science and Technology | Shen Y.,Shanghai JiaoTong University
Journal of Materials Chemistry A | Year: 2015

Carbothermal reduction could be employed as a facile technology for the synthesis of various novel materials, especially transition-metal-functionalized nanostructures. In particular, energy materials, such as ZnO, MnO2, and LiFePO4, combined with different carbon nanostructures have been widely synthesized via carbothermal reduction, which could be well established industrially due to its low-cost starting materials. In addition, a variety of carbon sources can be employed as comparatively low-cost carbon precursors for the synthesis of carbonaceous functional materials, such as porous carbon-coated magnetic nanoparticles (e.g., Co3O4@C, Fe3O4@C, and FeC3-C). These functional materials have great potential for use in energy and environmental applications. Carbothermal reduction methods possess some incomparable advantages, such as convenience, relatively low cost, and good repeatability, for commercial applications. However, they normally require a relatively high temperature for sustaining carbothermic reaction. Consequently, novel structures can also be derived from renewable, abundant carbon precursors. Examples include lignocellulosic biomass or other biological products derived from food or agricultural wastes (carbohydrates, cellulose, hemicellulose, lignin, chitin, inorganics, and proteins). Thermochemical conversion of biomass, including pyrolysis in an inert environment, has been developed for the production of energy and carbon materials. Furthermore, it is still a potential challenge to simultaneously produce high-quality biofuel products and synthesize value-added functionalized materials via in situ carbothermal reduction. This review will be a powerful resource for stimulating the development of sustainable metal-functionalized nanostructured materials by carbothermal reduction integrated with other advanced technologies, particularly for strengthening efforts towards novel materials for clean energy and environmental applications in the future sustainable society. This journal is © The Royal Society of Chemistry 2015.

Qi L.,Nanjing University of Information Science and Technology | Qi L.,University of Hawaii at Manoa | Wang Y.,University of Hawaii at Manoa
Journal of Climate | Year: 2012

The mesoscale mountain over the east Indochina Peninsula, named Annam Cordillera, plays a key role in shaping the South China Sea (SCS) summer climate in both the atmosphere and the ocean. However, its effect is not limited to the SCS. Ensemble simulations using a high-resolution regional atmospheric model with or without the mountain reveals that the Annam Cordillera has a significant impact on regional climate as far as 3000 km over south and east China, and western Northwest Pacific (WNP). By blocking/lifting the warm and moist air from the Bay of Bengal, the Annam Cordillera forces upward motion and precipitation on the windward side and subsidence on the leeward side, and a low-level southwesterly jet to the southeast tip of the Indochina Peninsula over the SCS. The latter gives rise to coastal upwelling and cold sea surface temperature (SST) filaments in the western SCS, reducing surface sensible and latent heat fluxes and thus suppressing convection over the SCS. Heating associated with the orographic rainfall forces a low-level anomalous easterly over the SCS and an anomalous cyclone and anticyclone in the midlower troposphere to the south and north, respectively. The anomalous circulation modifies the low-level moisture transport, reducing rainfall over the SCS and to the east of Taiwan Island over the WNP, while increasing rainfall as much as 15%-30% in a southwest-northeast-oriented belt extending from south China to the East China Sea. The cold SST filaments in the western SCS enhance the orographically induced circulation; however, its effect accounts for less than 50% of the direct effect of the orographic lifting/blocking. © 2012 American Meteorological Society.

Xu J.,Nanjing University of Information Science and Technology | Xu J.,George Mason University | Powell Jr. A.M.,The Center for Satellite Applications and Research
Atmospheric Research | Year: 2012

Based on the dynamical downscaling with the Advanced Research Weather (WRF-ARW) mesoscale model, the accuracy of the precipitation forecasts in Southwest Asia has been assessed. Results show that the accuracy of the 24-h and 48-h forecasts for precipitation is closely related to the complex topography of the mountain areas.To understand the impacts of the initial condition uncertainties on accuracy of the dynamical downscaling, a series of data assimilation experiments has been performed. The Advanced Television and Infrared Observation Satellite Operational Vertical Sounder (ATOVS) radiance observations and a data assimilation system named the Gridpoint Statistical Interpolation (GSI), developed by the National Centers for Environmental Prediction (NCEP), were used in this study. The results show that the satellite data provides beneficial information for improving the initial conditions for the dynamical model system and the "forecast" errors are reduced for most locations within the 24-h hindcasts. © 2012 Elsevier B.V.

Xiao B.,Nanjing University of Information Science and Technology
Zeitschrift fur Kristallographie - New Crystal Structures | Year: 2012

C18H18CuN4O10, triclinic, P1μ (no. 2), a = 7.2610(4) Å, b = 7.7534(6) Å, c = 9.5266(7) Å, α = 72.429(7)°, β = 82.633(5)°, γ = 72.083(6)°, V = 486.1 Å3, Z = 1, Rgt(F) = 0.032, wRref(F2) = 0.066, T = 296 K. © by Oldenbourg Wissenschaftsverlag, München.

Lu C.,Nanjing University of Information Science and Technology | Huang W.,University of Kansas | Van Vleck E.S.,University of Kansas
Journal of Computational Physics | Year: 2013

The cutoff method, which cuts off the values of a function less than a given number, is studied for the numerical computation of nonnegative solutions of parabolic partial differential equations. A convergence analysis is given for a broad class of finite difference methods combined with cutoff for linear parabolic equations. Two applications are investigated, linear anisotropic diffusion problems satisfying the setting of the convergence analysis and nonlinear Lubrication-type equations for which it is unclear if the convergence analysis applies. The numerical results are shown to be consistent with the theory and in good agreement with existing results in the literature. The convergence analysis and applications demonstrate that the cutoff method is an effective tool for use in the computation of nonnegative solutions. Cutoff can also be used with other discretization methods such as collocation, finite volume, finite element, and spectral methods and for the computation of positive solutions. © 2013 Elsevier Inc.

Pan Q.,Nanjing University of Information Science and Technology
Chinese Optics Letters | Year: 2012

A novel method to measure droplet size and complex refractive index simultaneously by rainbow detecting is presented. A new mathematic model for rainbow pattern of absorbing droplet is built. Based on this model, a series of new formulas to measure droplet imaginary part of refractive index is derived. Then a new inverse algorithm for simultaneously measure droplet size and the complex refractive index is presented, which is verified by simulation experiments under different conditions. © 2012 Chinese Optics Letters.

Xu J.,Tsinghua University | Wang L.,Tsinghua University | Zhu Y.,Tsinghua University | Zhu Y.,Nanjing University of Information Science and Technology
Langmuir | Year: 2012

The decontamination of bisphenol A (BPA) from aqueous solution by graphene adsorption was investigated. The maximum adsorption capacity (q m) of graphene for BPA obtained from a Langmuir isotherm was 182 mg/g at 302.15 K, which was among the highest values of BPA adsorption compared with other carbonaceous adsorbents according to the literature. Both π-π interactions and hydrogen bonds might be responsible for the adsorption of BPA on graphene, and the excellent adsorption capacity of graphene was due to its unique sp 2-hybridized single-atom-layer structure. Therefore, graphene could be regarded as a promising adsorbent for BPA removal in water treatment. The kinetics and isotherm data can be well described by the pseudo-second-order kinetic model and the Langmuir isotherm, respectively. The thermodynamic studies indicated that the adsorption reaction was a spontaneous and exothermic process. Besides, the presence of NaCl in the solution could facilitate the adsorption process, whereas the alkaline pH range and higher temperature of the solution were unfavorable. © 2012 American Chemical Society.

Xu L.,Nanjing University of Information Science and Technology | Li X.,Nanjing University of Science and Technology
Journal of Crystal Growth | Year: 2010

In this work, 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. The X-ray diffraction (XRD) analyses show that all the ZnO thin films prepared in this work have a hexagonal wurtzite structure and are preferentially oriented along the c-axis perpendicular to the substrate surface. After 1 at% Fe is doped, the crystalline quality and the preferential orientation of ZnO thin film are improved. However, when Fe-doping concentration is above 1 at%, the crystalline quality and the preferential orientation of ZnO thin film is weakened in turn. The surface morphology analyses of the samples show that the ZnO grain sizes tend to decrease with the increase of Fe-doping concentration. Fe-incorporation hardly influences the transmittance in the visible range, but the optical band-gaps of ZnO thin films gradually increase with the improved Fe-doping concentration. The photoluminescence spectra display that all the samples have an ultraviolet emission peak centered at 381 nm and the 1 at% Fe-doped ZnO thin film has the strongest ultraviolet emission peak. The above results suggest that 1 at% Fe-incorporation can improve the crystalline quality and enhance the ultraviolet emission of ZnO thin film. © 2009 Elsevier B.V. All rights reserved.

Pan Q.,Nanjing University of Information Science and Technology
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2012

The measurement of spray droplets size distribution and refractive index rainbow principle is studied. A novel inverse algorithm is presented, which can inverse droplets size distribution and refractive index simultaneously. The new algorithm, based on regularized non-negative least squares method (NNLS) and regularization method, which adjusts the refractive index and size distribution range during the inverse process according to the main rainbow peak positon and ratio of ridge and peak rainbow intensity, can inverse both droplets size distribution and refractive index simultaneously without pre-knowledge of droplets diameter distribution function and range. The algorithm and also can avoid mutli-sulution problems. Simulation results shows that even the signal noise ratio (SNR) drops to 5 dB, the inverse results of droplets size distribution coincide with the supposed distribution in most situations. The method has a relatively good precision and reliability.

Pan Q.,Nanjing University of Information Science and Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

A novel method for measuring droplet size and complex refractive index simultaneously using a CCD camera by rainbow detecting is proposed. A new mathematic model for rainbow pattern of absorbing droplet is built. Based on this model, a series of new formulas to measure droplet imaginary part of refractive index are derived. Then a new method for simultaneously measure droplet size and the complex refractive index is presented, which is verified by simulation experiments under different conditions. The experiment is performed to measure water with different dye concentrations. To avoid the effect of non-sphericity on refractive index detecting, a long and stable water cylinder instead of droplet is measured. Both the diameter and the complex refractive index of the liquid cylinder are detected by measuring the scattering rainbow light which is received by a linear CCD camera placed in the focus of the lens system. The result shows a satisfactory agreement with the theoretical analysis. © 2013 SPIE.

Su C.,Shandong University of Technology | Xu Y.,Shandong University of Technology | Zhang W.,Shandong University of Technology | Liu Y.,Shandong University of Technology | Li J.,Nanjing University of Information Science and Technology
Applied Surface Science | Year: 2012

A porous ceramic tube with superhydrophobic and superoleophilic surface was fabricated by sol-gel and then surface modification with polyurethane- polydimethysiloxane, and an oil-water separator based on the porous ceramic tube was erected to characterize superhydrophobic and superoleophilic surface's separation efficiency and velocity when being used to reclaim oil from oily water and complex oily water containing clay particle. The separator is fit for reclaiming oil from oily water. © 2011 Elsevier B.V. All rights reserved.

Jiang D.,CAS Institute of Atmospheric Physics | Sui Y.,University of Chinese Academy of Sciences | Lang X.,Nanjing University of Information Science and Technology
International Journal of Climatology | Year: 2016

Towards a better insight into the timing and climate change associated with a 2°C global warming above pre-industrial levels in the 21st century, here we perform an analysis of all pertinent experiments within the framework of the Coupled Model Intercomparison Project Phase 5 (CMIP5). Considering equally all available CMIP5 models, the probability of crossing the 2°C target before the year 2100 is 26, 86, and 100% for the Representative Concentration Pathways 2.6 (RCP2.6), 4.5 (RCP4.5), and 8.5 (RCP8.5) scenarios, respectively, with the median years of 2054 for RCP4.5 and 2042 for RCP8.5. A 2°C global warming would not be felt equally round the globe: stronger warming occurs over land than over the ocean, and the strongest warming occurs in the Arctic. Almost all temperature changes are larger than natural internal variability. Global average signal-to-noise ratios (S/N) of annual and seasonal temperature changes are in the range 3.2-5.0, and the largest values occur at low latitudes due to the lower background variability. Precipitation tends to increase at high latitudes but decrease in the subtropics, while all changes are smaller than natural internal variability except in parts of the high northern latitudes. The S/N of annual (seasonal) precipitation changes averages only 0.2 (no more than 0.1) for the globe. © 2016 Royal Meteorological Society.

Wu C.,Nanjing University of Information Science and Technology | Luo Y.,CAS Yantai Institute of Coastal Zone Research | Gui T.,Jiangsu University of Science and Technology | Huang Y.,CAS Nanjing Institute of Soil Science
Science of the Total Environment | Year: 2014

A total of 27 shallow groundwater samples were collected from the Taihu Lake region (TLR), to determine the concentrations of 14 organochlorine pesticide (OCP) species, identify their possible sources, and estimate health risk of drinking the shallow groundwater. All OCP species occurred in the shallow groundwater of TLR with high detection frequency except p, p'-dichlorodiphenyldichlorothane (p, p'-DDD) and p, p'-dichlorodiphenyltrichloroethane (p, p'-DDT). DDTs and hexachlorocyclohexanes (HCHs) were the dominant OCP contaminants in the shallow groundwater of TLR, and they account for 44.2% total OCPs. The low α-HCH/γ-HCH ratio, high β-HCH/(α+γ)-HCH ratio and β-HCH being the dominant HCH isomers for the majority of samples suggest that the HCHs were mainly from the historical use of lindane after a period of degradation. p, p'-DDE being the dominant DDT metabolite for all the samples indicated that the DDTs were mainly from the historical residues. Compositional analysis also suggested that there were fresh input sources of heptachlors, aldrins and endrins in addition to the historical residues. Correlation analysis indicated the hexachlorobenzene (HCB) impurity in the shallow groundwater of TLR was likely from the historical application of lindane and technical HCH (a mixture of HCH isomers that is produced by photochlorination of benzene). Carcinogenic risk values for α-HCH, heptachlor, heptachlor epoxide, aldrins and dieldrin in the shallow groundwater in majority area of TLR were found to be >10-6, posing a potentially serious cancer risk to those dependant on shallow groundwater for drinking water. © 2013 Elsevier B.V.

Ma R.,Nanjing University of Information Science and Technology
European Physical Journal B | Year: 2013

We numerically study the quantum Hall effect (QHE) in trilayer graphene with different stacking orders in the presence of interlayer bias under a strong magnetic field and disorder. In the biased ABA-stacked case, the Hall conductivity around the band center (Dirac point) is quantized as σxy = νe2 /h, where the filling factor ν is a nonzero integer. In the presence of disorder, the Hall plateaus can be destroyed through the float-up of extended levels toward the band center and higher plateaus disappear first. The central two plateaus around the band center are most robust against disorder scattering. With the increasing of the disorder strength, Hall plateaus are destroyed faster for the system with weaker magnetic field. In the biased ABC-stacked case, the Hall conductivity is quantized as σxy = νe /h (where ν is any integer) due to the split of the valley degeneracy by an opposite voltage bias added to the two layers. The central (n = 0) Landau level is also split, which leads to a pronounced ν = 0 plateau. Interestingly, the ν = 0 insulating state can be destroyed by a relatively strong disorder strength, where a metallic region is observed near zero energy. In the strong-disorder regime, all QHE states are destroyed by disorder, and the system transits into an insulating phase. © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2013.

Wu B.,Nanjing University of Information Science and Technology
Mathematical Methods in the Applied Sciences | Year: 2012

In this paper, we establish a Carleman estimate for a strongly damped wave equation in order to solve a coefficient inverse problems of retrieving a stationary potential from a single time-dependent Neumann boundary measurement on a suitable part of the boundary. This coefficient inverse problem is for a strongly damped wave equation. We prove the uniqueness and the local stability results for this inverse problem. The proof of the results relies on Carleman estimate and a certain energy estimates for hyperbolic equation with strongly damped term. Moreover, this method could be used for a similar inverse problem for an integro-differential equation with hyperbolic memory kernel. © 2012 John Wiley & Sons, Ltd.

Liu Y.,Brookhaven National Laboratory | Daum P.H.,Brookhaven National Laboratory | Lu C.,Brookhaven National Laboratory | Lu C.,Nanjing University of Information Science and Technology
Journal of Geophysical Research Atmospheres | Year: 2014

Hudson et al. [2012, hereafter H12] have lately shown that the standard deviation (ó) of droplet size distributions was inversely related to cloud condensation nuclei (CCN) concentration at 1% supersaturation (N CCN) for the in situ aircraft measurements collected during the Rain in Cumulus over the Ocean (RICO) project. Using adiabatic parcel model simulations for various values of updraft velocity (w), they further reported a tendency for the α- NCCN correlation to change signs from positive to negative as w increases beyond a certain value. The analysis of ó- NCCN correlation and its dependence on w certainly add new understanding of dispersion effect (e.g., Liu and Daum, 2002, LD02 hereafter; Liu et al., 2006b, LDY06 hereafter) and imply that like the more widely known aerosol effect on cloud droplet number concentration (N), dispersion effect may exhibit aerosol-limited and w-limited regimes such that dispersion effect can either diminish or enhance the cooling of number effect, depending on the regimes. However, there appears to be some misunderstanding/misinterpretation of LD02 and LDY06 concerning the use of relative dispersion as a measure of spectral width. Furthermore, our examination of the data reported in Table 1 of H12 shows that there is a positive correlation between NCCN and w, and thus it cannot be ruled out that the observed negative α- NCCN correlation is a manifestation of the covariation in w, or arises from the indirect effect of aerosol on cloud dynamics, or a combination of both. Below these points are detailed. © 2014. American Geophysical Union. All Rights Reserved.

Li S.-J.,Nanjing University of Information Science and Technology | Moog C.H.,CNRS Research Institute of Communication and Cybernetics of Nantes | Califano C.,University of Rome La Sapienza
Proceedings of the IEEE Conference on Decision and Control | Year: 2011

The accessibility of the class of driftless single-input nonlinear time-delay systems is fully characterized for the first time. This result is obtained through the introduction of new tools within a geometric approach recently introduced in the literature. Moreover, all those possible autonomous elements, which can depend on the variables with time-delay, are also characterized when the system is not accessible and in consequence, a canonical form of those systems is deduced. © 2011 IEEE.

Lin Z.,CAS Institute of Atmospheric Physics | Wang B.,University of Hawaii at Manoa | Wang B.,Nanjing University of Information Science and Technology
Climate Dynamics | Year: 2016

The strength of the East Asian summer monsoon and associated rainfall has been linked to the western North Pacific subtropical high (WNPSH) and the lower-tropospheric low pressure system over continental East Asia (EA). In contrast to the large number of studies devoted to the WNPSH, little is known about the variability of the East Asian continental low. The present study delineates the East Asian continental low using 850-hPa geopotential height. Since the low is centered over northern EA (NEA), we refer to it as the NEA low (NEAL). We show that the intensity of the NEAL has large interannual variation, with a dominant period of 2–4 years. An enhanced NEAL exhibits a barotropic structure throughout the whole troposphere, which accelerates the summer-mean upper-tropospheric westerly jet and lower-tropospheric monsoon westerly to its south. We carefully identify the anomalous NEAL-induced rainfall anomalies by removal of the tropical heating effects. An enhanced NEAL not only increases rainfall locally in northern Northeast China, but also shifts the East Asian subtropical front northward, causing above-normal rainfall extending eastward from the Huai River valley across central-northern Japan and below-normal rainfall in South China. The northward shift of the East Asian subtropical front is attributed to the following processes without change in the WNPSH: an enhanced NEAL increases meridional pressure gradients and the monsoon westerly along the East Asian subtropical front, which in turn induces a cyclonic shear vorticity anomaly to its northern side. The associated Ekman pumping induces moisture flux convergence that shifts the East Asian subtropical front northward. In addition, the frequent occurrence of synoptic cut-off lows is found to be associated with an enhanced NEAL. Wave activity analysis indicates that the interannual intensity change of the NEAL is significantly associated with the extratropical Polar Eurasian teleconnection, in addition to the forcing of the tropical WNP heating. © 2015, Springer-Verlag Berlin Heidelberg.

Zhang Y.,CAS Nanjing Institute of Soil Science | Zhang Y.,Nanjing University of Information Science and Technology | Ding W.,CAS Nanjing Institute of Soil Science
Aquatic Botany | Year: 2011

In this study, we aimed to understand the influence of plant type on the monthly variations of diel CH4 fluxes from Spartina alterniflora and Suaeda salsa of coastal salt marshes at three growth stages (July, August and September). Dissolved CH4 concentrations in porewater and sediment redox potentials were monitored, as were aboveground plant biomass and stem densities. CH4 fluxes exhibited clear monthly variations and peaked in September in the S. alterniflora and S. salsa mesocosms. However, no discernible diel variation was observed in the CH4 flux in the S. salsa mesocosm, probably due to its weak gas transport capacity. By contrast, notable diel variations of CH4 flux with the peak of 1.42 and 3.67mgCH4m-2h-1 at 12:00 and the lowest of 0.75 and 2.11mgCH4m-2h-1 at 3:00 or 6:00 were observed in the S. alterniflora mesocosm on 11 August and 11 September, respectively, but not in July mainly due to low plant biomass masking diel variations in the porewater CH4 concentration. The ratios of the maximum flux to minimum flux over the course of the day in the S. alterniflora mesocosm on 10 July, 11 August and 11 September were 1.28, 1.89 and 1.76, respectively, and corresponding values for porewater CH4 concentration were 1.31, 1.39 and 1.17, respectively. CH4 flux significantly correlated with CH4 concentration in porewater, and both were significantly related to air temperature. These findings indicate that CH4 production and CH4 flux at the middle growth stage (August) exhibited greater responses to changes in air temperature, which in turn induced the higher diel variation. The higher diel cycle for CH4 flux in August than in September was likely due to the higher proportion of CH4 oxidized during diffusion within the aerenchyma system. Our results suggest that the extent of diel variations in CH4 flux may have depended on the gas transport capacity of plants, and the highest diel variation occurred at the middle growth stage. © 2011 Elsevier B.V.

Zhou H.,Nanjing University of Information Science and Technology | Bukenya J.O.,Alabama A&M University
Energy Policy | Year: 2016

The paper examines the extent to which consumers' willingness-to-pay for energy-efficient room air conditioners may be altered by correcting the information inefficiency on the China Energy Label. The data are collected from a discrete choice experiment with two alternatives (variable-speed and constant-speed room air conditioners) characterized by attributes of brand, purchase price and energy grade. Three versions of the questionnaires with choice sets differing only in energy consumption indicators were distributed randomly to 1602 potential consumers in Nanjing, China and a sample of 1569 was obtained after dropping missing data. The analysis with multinomial and mixed logit models reveal that the price premium that consumers are willing to pay for a variable-speed room AC over a constant-speed room AC increases significantly when energy consumption information becomes comparable and additional energy-related information is provided. Furthermore, the impact of information on WTP varies under different energy-saving scenarios. It is suggested that China Energy Label should correct information inefficiency by adopting same energy indicators for room ACs with different technologies and providing energy consumption information based on different climate zones. © 2016 Elsevier Ltd.

Wang C.,Nanjing University of Information Science and Technology | Wang C.,Tsinghua University | Zhang G.,Tsinghua University | Wang X.,Tsinghua University | He X.,Zhejiang University
Surface and Coatings Technology | Year: 2011

In order to study the effect of magnet enhanced plasma on polymer surface, a dielectric barrier discharge (DBD) setup with and without magnet is presented and used to modify poly(ethylene terephthalate) (PET) films at atmospheric pressure in ambient air. Surface analysis and characterization of the air plasma-treated PET films are performed using contact angle measurements, surface free energy, Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). The results show that air plasma leads to an obvious decrease in contact angle and increase in surface free energy. And surface wettability of the PET films treated by DBD with magnet is better than that without magnet. AFM images show an increase in surface roughness due to plasma etching. It is shown that O and N elements are introduced onto PET film surfaces as oxygen- and nitrogen-containing functional groups. The oxygen-containing groups can be identified as C. O, C. O and O. C. O. Their concentrations of the PET films treated with magnet are more than those treated without magnet. The difference is attributed to more active particles generated in DBD with magnet. Therefore, magnet field plays an important role in improving surface wettability of polymers. © 2011 Elsevier B.V.

Chen Y.-Y.,Nanjing University of Information Science and Technology | Wang J.,Nanjing University of Science and Technology | Wang Q.-H.,Nanjing University of Science and Technology | Li Z.-H.,Nanjing University of Science and Technology
Optics Letters | Year: 2012

In this Letter, moiré and emission tomography are integrated to visualize and diagnose high-temperature flow fields, and a jet flame is chosen as a practical example for experiment. The refractive index and intensity distributions are simultaneously obtained by moiré and emission tomography, respectively. Based on the intensity distribution, the structure of the jet flame is well visualized, so that the spatial distribution of species composition can be considered in the temperature reconstruction process. Finally, the refractive index and intensity distributions are matched, and a partition model is adopted to reconstruct the temperature distribution of the jet flame. © 2012 Optical Society of America.

Chen X.,Nanjing University of Information Science and Technology
Key Engineering Materials | Year: 2010

To overcome the shortcomings of wired temperature and humidity measurement system, a temperature and humidity measuremet system based on wireless sensor networks was designed. the components of the system and its working principle were described in detail. Its nodes use a digital temperature and humidity sensor SHT15 for data collection, wireless transmission chip CC1100e for data short-range wireless transceiver and the wireless network, and AT89S52 microcontroller for controlling core. Nodes communicate with the background host through serial interfaces. The system can achieve environmental temperature and humidity dynamically and comprehensive real-time monitoring. Node has a dual function as terminals and routers, in addition to data processing, but also for other nodes to forward the temperature and humidity data storage, management, and integration, and taking in collaboration with other nodes to complete some specific tasks. The system has some advantages such as low cost, low power consumption and small size, which has a good application prospects. © 2010 Trans Tech Publications.

Liu Z.-S.,Nanjing University of Information Science and Technology | Sechovsky V.,Charles University | Divis M.,Charles University
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2012

A quantum simulation model was developed and employed in this work to study the magnetism of an assumed 3d nanoparticle, which consists of an antiferromagnetic core and a ferromagnetic shell. The calculated magnetic structures, specific heat, magnetization and hysteresis curves are reasonable physically, demonstrating the correctness of the quantum model and the applicability of the simulation algorithm. © 2011 Elsevier B.V. All rights reserved.

Huang C.-C.,Nanjing Normal University | Huang C.-C.,Mississippi State University | Li Y.-M.,Nanjing Normal University | Sun D.-Y.,Nanjing University of Information Science and Technology | Le C.-F.,University of South Florida
IEEE Transactions on Geoscience and Remote Sensing | Year: 2011

Microcystis aentginosa (MA), which is one kind of cyanobacteria, is the primary algal species in Taihu Lake. The MA bloom has a significantly negative effect on the human health and water environment ecosystem. The monitoring and prediction of MA bloom become more and more critical for the security of drinking water source and environment in the Taihu Lake area. In this paper, the percentage of MA was estimated from remote-sensing reflectance via a novel spectral shape genetic optimization algorithm. This algorithm focuses on the shape of remote-sensing reflectance, and it can remove the influence of the amplitude of remote-sensing reflectance from the retrieval result. The accuracy of this optimization algorithm is acceptable according to both simulated and in situ data. The percentage of mean square root (RMSP) of the percentage of the phytoplankton absorption coefficient to the total absorption coefficient at 440 nm [ar (440 nm)] between the retrieved and the simulated is 18.39%. The RMSP of the total absorption coefficient at 440 nm [a (440 nm)] between the retrieved and the simulated is 3.65%. The RMSP of the percentage of MA [S f] between the retrieved and the simulated is 13.60%. The RMSP of the colored dissolved organic matter (CDOM) absorption coefficient slope [S] between the retrieved and the simulated is 5.89%. The RMSP of the particle backscatter coefficient slope [Y] between the retrieved and the simulated is 30.46%. In Taihu Lake, the RMSPs of ar (440 nm), a (440 nm), S f , and S between the retrieved and the measured are 36.59%, 35.70%, 19.25%, and 16.80%, respectively. The retrieved percentage of MA (Sf) and Scenedesmus obliquus (1-Sf) by this model from August 2006, October 2006, to November 2008 indicates the variation trend of algal species in different seasons. This trend accords with the results from previous studies and observations. This paper extends and advances the previous retrieval methods and confirms that the genetic optimization algorithm can be used to retrieve the information of water constituents in the high turbid and eutrophic inland water mass. © 2011 IEEE.

Qiu Z.,Nanjing University of Information Science and Technology
Optics Express | Year: 2013

Distribution of the suspended particulate matter (SPM) concentration is a key issue for analyzing the deposition and erosion variety of the estuary and evaluating the material fluxes from river to sea. Satellite remote sensing is a useful tool to investigate the spatial variation of SPM concentration in estuarial zones. However, algorithm developments and validations of the SPM concentrations in Yellow River Estuary (YRE) have been seldom performed before and therefore our knowledge on the quality of retrieval of SPM concentration is poor. In this study, we developed a new simple optical model to estimate SPM concentration in YRE by specifying the optimal wavelength ratios (600-710 nm)/ (530-590 nm) based on observations of 5 cruises during 2004 and 2011. The simple optical model was attentively calibrated and the optimal band ratios were selected for application to multiple sensors, 678/551 for the Moderate Resolution Imaging Spectroradiometer (MODIS), 705/560 for the Medium Resolution Imaging Spectrometer (MERIS) and 680/555 for the Geostationary Ocean Color Imager (GOCI). With the simple optical model, the relative percentage difference and the mean absolute error were 35.4% and 15.6 gm-3 respectively for MODIS, 42.2% and 16.3 gm-3 for MERIS, and 34.2% and 14.7 gm -3 for GOCI, based on an independent validation data set. Our results showed a good precision of estimation for SPM concentration using the new simple optical model, contrasting with the poor estimations derived from existing empirical models. Providing an available atmospheric correction scheme for satellite imagery, our simple model could be used for quantitative monitoring of SPM concentrations in YRE. © 2013 Optical Society of America.

Wang W.,National United University | Shen X.,Nanjing University of Information Science and Technology | Huang W.,Changzhou Meteorological Bureau
Boundary-Layer Meteorology | Year: 2016

We compare daytime planetary boundary-layer (PBL) characteristics under fair-weather conditions simulated using a single column version of the Weather Research and Forecasting model with different PBL parametrization schemes. The model is driven only by prescribed surface heat fluxes and horizontal pressure gradient forcing. Parametrizations for all physical processes except for turbulence and transport in the PBL are turned off in the simulations to ensure the discrepancies in the simulated PBL flow are due only to differences in the PBL schemes. A large-eddy simulation (LES) of the evolution of a daytime PBL is performed as a benchmark to examine how well a PBL parametrization scheme reproduces the LES results, and performance statistics are compared to rank those schemes. In general, hybrid local and non-local schemes such as the Yonsei University and Asymmetrical Convective Model (version 2) schemes perform better in reproducing the LES results, particularly well-mixed features, than do local schemes. Among local schemes, the University of Washington scheme produces the results closest to the LES. Local schemes, such as those of Mellor–Yamada–Janjic and Mellor–Yamada–Nakanishi–Niino, simulate too low an entrainment flux, while PBL heights diagnosed from the simulations using local schemes are lower than those from the LES results. Hybrid local and non-local schemes are more sensitive to vertical grid resolution than local schemes. With a higher vertical resolution in the PBL, the schemes using the eddy-diffusivity and mass-flux methods perform better. Differences in the values of eddy diffusivity, length scale, and turbulence kinetic energy and their vertical distributions are large. © 2016 Springer Science+Business Media Dordrecht

Deng P.,Nanjing University of Information Science and Technology | Zhu J.,University of Wyoming
Journal of Hydrology | Year: 2016

While Green-Ampt model has been widely used in infiltration calculations through unsaturated soils, upscaling this model for applications in heterogeneous formations remains difficult. In this study, how to upscale soil parameters in the Green-Ampt model for vertically layered soils is examined. The main idea of upscaled effective parameters is to capture infiltration behavior in layered soil formations using only one set of parameters derived from the parameters of individual layers, such that the layered system can be replaced by an equivalent homogeneous medium. The general p-order power mean was proposed to represent the upscaling schemes of the Green-Ampt model. The optimal p value was determined by a general requirement of same total infiltration time for the layered formation and the equivalent homogeneous medium. The p-order power mean for the Green-Ampt parameters can capture the infiltration rates in the layered formations well, illustrating that the proposed upscaling schemes are reasonable to represent the overall behaviors of the heterogeneous layered formations. The structure of layered formations can significantly influence the upscaling results. However, when the number of layers becomes large, the layered formations tend to show homogeneity and the layer structure becomes less important. The results demonstrated that the scheme based on the harmonic mean for the saturated hydraulic conductivity and the general p-order power mean for the wetting front suction head can well capture the overall infiltration behaviors in both the coarse-layer-on-top and fine-layer-on-top formations, and thus is recommended as a general upscaling scheme when using the upscaled Green-Ampt model in layered formations. © 2016 Elsevier B.V.

Gu Y.,CAS Institute of Atmospheric Physics | Gu Y.,University of Chinese Academy of Sciences | Liao H.,Nanjing University of Information Science and Technology | Bian J.,CAS Institute of Atmospheric Physics
Atmospheric Chemistry and Physics | Year: 2016

We use the global three-dimensional Goddard Earth Observing System chemical transport model (GEOS-Chem) to examine the contribution of nitrate aerosol to aerosol concentrations in the upper troposphere and lower stratosphere (UTLS) over the Tibetan Plateau and the South Asian summer monsoon (TP/SASM) region during summertime of year 2005. Simulated surface-layer aerosol concentrations are compared with ground-based observations, and simulated aerosols in the UTLS are evaluated by using the Stratospheric Aerosol and Gas Experiment II satellite data. Simulations show elevated aerosol concentrations of sulfate, nitrate, ammonium, black carbon, organic carbon, and PM2.5 (particles with diameter equal to or less than 2.5 μm, defined as the sum of sulfate, nitrate, ammonium, black carbon, and organic carbon aerosols in this study) in the UTLS over the TP/SASM region throughout the summer. Nitrate aerosol is simulated to be of secondary importance near the surface but the most dominant aerosol species in the UTLS over the studied region. Averaged over summertime and over the TP/SASM region, CNIT (the ratio of nitrate concentration to PM2.5 concentration) values are 5–35 % at the surface, 25–50 % at 200 hPa, and could exceed 60 % at 100 hPa. The mechanisms for the accumulation of nitrate in the UTLS over the TP/SASM region include vertical transport and the gas-to-aerosol conversion of HNO3 to form nitrate. The high relative humidity and low temperature associated with the deep convection over the TP/SASM region are favorable for the gas-to-aerosol conversion of HNO3. © Author(s) 2016.

Ma R.,Nanjing University of Information Science and Technology
European Physical Journal B | Year: 2013

We numerically study the thermoelectric transport in AB- and AA-stacked bilayer graphene in the presence of a strong magnetic field and disorder. In the AB-stacked case, we find that the thermoelectric conductivities display different asymptotic behaviors, depending on the ratio between the temperature and the width of the disorder-broadened Landau levels (LLs), similar to those of monolayer graphene. In the high temperature regime, the transverse thermoelectric conductivity α xy saturates to a universal value 5.54k B e/h at the center of each LL, and displays a linear temperature dependence at low temperatures. The calculated Nernst signal has a peak with a height of the order of k B /e, and the thermopower changes sign at the central LL. We attribute this unique behavior to the coexistence of particle and hole LLs. In the AA-stacked bilayer case, it is found that the thermoelectric transport properties are consistent with the behavior of a band insulator. The obtained results demonstrate the sensitivity of the thermoelectric conductivity to the band gap near the Dirac point. © 2013 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.

Luo Q.,Nanjing University of Information Science and Technology | Zeng Z.,Huazhong University of Science and Technology | Liao X.,Huazhong University of Science and Technology
Neurocomputing | Year: 2011

In this paper, the global exponential stability in Lagrange sense for continuous neutral type recurrent neural networks (NRNNs) with multiple time delays is studied. Three different types of activation functions are considered, including general bounded and two types of sigmoid activation functions. By constructing appropriate Lyapunov functions, some easily verifiable criteria for the ultimate boundedness and global exponential attractivity of NRNNs are obtained. These results can be applied to monostable and multistable neural networks as well as chaos control and chaos synchronization. © 2010 Elsevier B.V.

Chen Y.-G.,Nanjing Normal University | Fang J.-H.,Nanjing University of Information Science and Technology
European Journal of Combinatorics | Year: 2014

For A⊆Z, we study the gaps in the sequence of all sums of h pairwise distinct elements of A. For example, the following result is proved: for any integer h ≥ 3, there exists A⊆Z such that every integer can be uniquely (neglecting the order) represented as a sum of h not necessarily distinct elements of A, and for any integer ℓ ≥ 1, in the sequence of all sums of ℓ pairwise distinct elements of A, the gaps can be arbitrarily large. Several questions are posed in this paper. © 2014 Elsevier Ltd.

Cao N.,Nanjing University of Information Science and Technology
Optik | Year: 2015

This paper presents new Lidar technology with which to remove the noise effect in aerosol extinction coefficient inversion, thereby yielding coefficients with high accuracy. Based on the Lidar principle, the new inversion method is calculated theoretically. As a case study, aerosols were measured regularly using Mie Lidar in the northern suburbs of Nanjing City, China, using the new method to calculate the aerosol extinction coefficient. The laser source energy was varied to obtain Lidar return signals with different intensities, which were then used to remove the noise effect, yielding inverse aerosol extinction coefficients with high accuracy. A numerical simulation was performed to examine the aerosol extinction coefficients calculated using Lidar return signals with different laser powers. The simulation results reveal that the different laser energies yield identical profiles of inversed aerosol extinction coefficients, consistent with the experimental results. The experimental and simulation results demonstrate the validity of the theoretical calculations. © 2015 Elsevier GmbH.

Man W.,CAS Institute of Atmospheric Physics | Man W.,Nanjing University of Information Science and Technology | Zhou T.,CAS Institute of Atmospheric Physics | Zhou T.,Chinese Academy of Sciences
Advances in Atmospheric Sciences | Year: 2014

The spatial patterns and regional-scale surface air temperature (SAT) changes during the last millennium, as well as the variability of the East Asian summer monsoon (EASM) were simulated with a low-resolution version of Flexible Global Ocean-Atmosphere-Land-Sea-ice (FGOALS-gl) model. The model was driven by both natural and anthropogenic forcing agents. Major features of the simulated past millennial Northern Hemisphere (NH) mean SAT variations, including the Medieval Climate Anomaly (MCA), the Little Ice Age (LIA) and the 20th Century Warming (20CW), were generally consistent with the reconstructions. The simulated MCA showed a global cooling pattern with reference to the 1961-90 mean conditions, indicating the 20CW to be unprecedented over the last millennium in the simulation. The LIA was characterized by pronounced coldness over the continental extratropical NH in both the reconstruction and the simulation. The simulated global mean SAT difference between the MCA and LIA was 0.14°C, with enhanced warming over high-latitude NH continental regions. Consistencies between the simulation and the reconstruction on regional scales were lower than those on hemispheric scales. The major features agreed well between the simulated and reconstructed SAT variations over the Chinese domain, despite some inconsistency in details among different reconstructions. The EASM circulation during the MCA was stronger than that during the LIA The corresponding rainfall anomalies exhibited excessive rainfall in the north but deficient rainfall in the south. Both the zonal and meridional thermal contrast were enhanced during the MCA. This temperature anomaly pattern favored a stronger monsoon circulation. © 2014 Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg.

Zhang B.,Nanjing University of Information Science and Technology | Zhang B.,Bedford Institute of Oceanography | Perrie W.,Bedford Institute of Oceanography
Bulletin of the American Meteorological Society | Year: 2012

A C-band Cross-Polarization Ocean (C-2PO) model is presented, based on RADARSAT-2 fine quad-polarization mode SAR measurements. The C-2PO model is insensitive to wind direction and radar incidence angle, and thus it is a straightforward mapping of observed cross-polarized NRCS to wind speed. C-2PO avoids the errors in wind speed retrievals that can occur in CMOD5.N due to errors in wind directions. In presently available quad-polarization data, the observed NRCS in cross polarization increases linearly with wind speed, up to 26 m s -1, which indicates that it could potentially be used to retrieve hurricane winds, including eye structure observations. In comparisons of wind speeds derived from C-2PO and CMOD5.N with buoy data, SFMR measurements, and H*Wind analysis, we show that C-2PO has slightly smaller scatter than CMOD5.N for wind speeds <20 m s -1; for wind speeds in the range of 20- 38 m s -1, the difference in scatter is significant. © 2012 American Meteorological Society.

Xiao B.,Nanjing University of Information Science and Technology
Zeitschrift fur Kristallographie - New Crystal Structures | Year: 2012

C20H20N2NiO9, monoclinic, P21/n (no. 14), a = 7.5426(2) Å, b = 13.3693(4) Å, c = 20.7286(7) Å, β = 92.020(3)°, V = 2089.0 Å3, Z = 4, Rgt(F) = 0.033, wRref(F2) = 0.082, T = 296 K. © by Oldenbourg Wissenschaftsverlag, München.

Xiao B.,Nanjing University of Information Science and Technology
Zeitschrift fur Kristallographie - New Crystal Structures | Year: 2012

C15H11CuN2O4, monoclinic, C12/c1 (no. 15), a = 13.549(2) Å, b = 9.8711(7) Å, c = 20.483(2) Å, β = 100.88(1)°, V = 2690.3 Å3, Z = 8, Rgt(F) = 0.046, wRref(F2) = 0.051, T = 296 K. © by Oldenbourg Wissenschaftsverlag, München.

Xiao B.,Nanjing University of Information Science and Technology
Zeitschrift fur Kristallographie - New Crystal Structures | Year: 2012

C10H14CoN4O12, triclinic, P1μ (no. 2), a = 5.009(1) Å, b = 8.130(2) Å, c = 9.550(2) Å, α = 74.44(2)°, β = 84.72(2)°, γ = 88.89(2)°, V = 373.0 Å3, Z = 1, Rgt(F) = 0.059, wRref(F2) = 0.158, T = 296 K. © by Oldenbourg Wissenschaftsverlag, München.

Xiao B.,Nanjing University of Information Science and Technology
Zeitschrift fur Kristallographie - New Crystal Structures | Year: 2012

C20H20CoN2O9, monoclinic, P21/n (no. 14), a = 7.5748(3) Å, b = 13.4983(5) Å, c = 20.5241(7) Å, β = 92.585(3)°, V = 2096.4 Å3, Z = 4, Rgt(F) = 0.034, wRref(F2) = 0.089, T = 293 K. © by Oldenbourg Wissenschaftsverlag, München.

Zhao T.L.,Nanjing University of Information Science and Technology | Gong S.L.,Environment Canada | Gong S.L.,Chinese Academy of Meteorological Sciences | Huang P.,Environment Canada | Lavoue D.,DL Modeling and Research
Atmospheric Chemistry and Physics | Year: 2012

Based on a 10-yr simulation with the global air quality modeling system GEM-AQ/EC, the northern hemispheric aerosol transport with the inter-annual and seasonal variability as well as the mean climate was investigated. The intercontinental aerosol transport is predominant in the zonal direction from west to east with the ranges of inter-annual variability between 14% and 63%, and is 0.5-2 orders of magnitude weaker in the meridional direction but with larger inter-annual variability. The aerosol transport is found to fluctuate seasonally with a factor of 5-8 between the maximum in late winter and spring and the minimum in late summer and fall. Three meteorological factors controlling the intercontinental aerosol transport and its inter-annual variations are identified from the modeling results: (1) Anomalies in the mid-latitude westerlies in the troposphere. (2) Variations of precipitation over the intercontinental transport pathways and (3) Changes of meteorological conditions within the boundary layer. Changed only by the meteorology, the aerosol column loadings in the free troposphere over the source regions of Europe, North America, South and East Asia vary inter-annually with the highest magnitudes of 30-37% in January and December and the lowest magnitudes of 16-20% in August and September, and the inter-annual aerosol variability within the boundary layer influencing the surface concentrations with the magnitudes from 6% to 20% is more region-dependent. As the strongest climatic signal, the El Ni±o-Southern Oscillation (ENSO) can lead the anomalies in the intercontinental aerosols in El Ni ±o-and La Ni ±a-years respectively with the strong and weak transport of the mid-latitude westerlies and the low latitude easterlies in the Northern Hemisphere (NH). © 2012 Author(s).

Xu J.,Tsinghua University | Zhu Y.-F.,Tsinghua University | Zhu Y.-F.,Nanjing University of Information Science and Technology
Wuli Huaxue Xuebao/ Acta Physico - Chimica Sinica | Year: 2013

The elimination of bisphenol A (BPA) from aqueous solution by adsorption on graphene oxide (GO) was investigated. The maximum adsorption capacity (qm) of GO for BPA estimated from the Langmuir isotherm was 87.80 mg·g-1 at 25 °C. The required contact time to reach adsorption equilibrium was about 30 min, which was much shorter than that of activated carbon. The adsorption kinetics and isotherm data fitted well with the pseudo-second-order kinetic model and the Langmuir isotherm, respectively. Neutral pH and low solution temperature were favorable for adsorption, whereas the presence of NaCl in the solution was unfavorable. The GO had good recyclability and could be reused several times with a slight decline in adsorption ability. Both hydrogen bonding and π-π interaction were thought to be responsible for the adsorption of BPA on GO. The excellent adsorption capacity and high adsorption rate of GO result from its sheet-like structure and the abundant oxygen-containing groups on its surface. Although qm of GO for BPA is lower than that of graphene, GO has the benefits of large scale production, a hydrophilic surface with plenty of oxygen-containing groups, and good dispersion in water. Therefore, GO can be regarded as a good potential adsorbent for water treatment. © Editorial office of Acta Physico-Chimica Sinica.

Wang L.,Nanjing University of Information Science and Technology | Zhu X.,Nanjing Normal University
Journal of Alloys and Compounds | Year: 2016

Using first-principles density functional theory based method we have investigated the electronic, magnetic and thermodynamic properties of Heusler alloy Co2Mn1-xTixSn. From analysis of elastic constants, we find that the cubic L21 phase is stable and all the alloys prone to ductility for Co2Mn1-xTixSn alloy. The total magnetic moment decreases with increasing x, in agreement with the generalized Slater-Pauling rule. Band structure calculations show that the minority DOS exhibits a gap around Fermi level confirming the half-metallic character of the material for all the concentrations studied and the Fermi level can be shifted within the minority spin gap by changing the Ti concentration. The Curie temperature TC estimated from the effective exchange constant J0 decreases with x, and qualitatively accords with the experimental values. Finally, by using a quasi-harmonic Debye model, the temperature dependent bulk modulus, heat capacity and coefficient of thermal expansion have been obtained in the present work. © 2016 Elsevier B.V.

Liu Q.,Nanjing University of Information Science and Technology | Wu H.G.,Zhengzhou University of Light Industry
Comptes Rendus Chimie | Year: 2013

Three new Cu(II) complexes with carboxylic ligand, namely {[Cu(qc) 2(py)]·4H2O}∞ (1), [Cu(qc) 2(4,4′-bpy)]∞ (2) and [Cu(pc)(2,2′-bpy) (H2O)]2·H2O (3) (Hqc = 3-hydroxy-2-quinoxalinecarboxylic acid, H2pc = 4-hydroxyphthalic acid, py = pyrazine) have been synthesized and characterized. In both 1 and 2, each Cu(II) ion is coordinated by two quinoxalinecarboxylate moieties in the equatorial plane and two 4,4′-bpy or pyrazine units provide coordination in the axial positions, thus, resulting in a 1-D polymeric chain structure. Complex 3 has a dimeric structure in which two Cu(II) cations are bridged by two deprotonated pc2- ligands and two 2,2′-bpy molecules. As heterogeneous catalysts, the title complexes showed high catalytic efficiency in the green oxidative polymerization of 2,6-dimethylphenol (DMP) to poly(1,4-phenylene ether) (PPE) in the presence of H2O2 as oxidant in water under mild conditions. Moreover, they allow reuse without significant loss of activity through four runs, which suggests that these catalysts are efficient, mild, and easily recyclable for the oxidative coupling of DMP. The preliminary study of the catalytic-structural correlations suggests that the coordination environment of the metal center plays an important role in the improvement of their catalytic efficiencies. © 2012 Académie des sciences.

Xiao B.,Nanjing University of Information Science and Technology
Zeitschrift fur Kristallographie - New Crystal Structures | Year: 2012

C19H20HgI2N4, monoclinic, C12/c1 (no. 15), a = 19.471(2) Å, b = 10.564(1) Å, c = 21.295(3) Å, β = 100.34(1)°, V = 4309.1 Å3, Z = 8, R gt(F) = 0.041, wRref(F2) = 0.087, T = 296 K. © 2012 by Oldenbourg Wissenschaftsverlag, München.

Xiao B.,Nanjing University of Information Science and Technology
Zeitschrift fur Kristallographie - New Crystal Structures | Year: 2012

C160H152Cu8N16O68, monoclinic, C12/c1 (no. 15), a = 20.423(4) Å, b = 12.023(2) Å, c = 16.219(3) Å, β = 94.18(2)°, V = 3972.0 Å3, Z = 1, Rgt(F) = 0.056, wRref(F2) = 0.141, T = 296 K. © by Oldenbourg Wissenschaftsverlag, München.

Sheng J.,University of Arkansas | Wang J.,University of Arkansas | Wang J.,Nanjing University of Information Science and Technology | Xiao M.,University of Arkansas | Xiao M.,Nanjing University
Optics Letters | Year: 2013

We have experimentally observed optical multistabilities (OMs) simultaneously on both the signal and generated Stokes fields in an optical ring cavity with a coherently prepared multilevel atomic medium. The two observed OMs, which are governed by different physical processes, are coupled via the multilevel atomic medium and exhibit similar threshold behaviors. By modulating the cavity input (signal) field with positive or negative pulses, dualchannel all-optical multistate switching has been realized and synchronously controlled, which can be useful for increasing communication and computation capacities. © 2013 Optical Society of America.

Wang Z.,Guangdong University of Technology | Duan Z.,University of Nottingham | Zhao X.,De Montfort University | Chen M.,Nanjing University of Information Science and Technology
Solar Energy | Year: 2012

This paper reported a dedicated study of a novel façade-based solar loop heat pipe (LHP) water heating system using both theoretical and experimental methods. This system employs a modular panel incorporating a unique loop heat pipe that is able to serve as part of the building façade or a decoration layer of the façade, thus creating a façade integrated, low cost, highly efficient and aesthetically appealing solar water heating structure. Taking into account heat balances occurring in different parts of the system, e.g., solar absorber, heat pipes loop, heat exchanger and storage tank, a dedicated computer model was developed to investigate the dynamic performance of the system. An experimental rig was also established to evaluate the performance of such a prototype system through measurement of various operational parameters, e.g., solar radiation, temperatures and flow rates of the heat pipe fluid and water. Through comparison between the testing and modelling results, the model has been approved to be able to give a reasonable accuracy for predicting the performance of the LHP system. Two types of glass covers, i.e., double glazed/evacuated tubes and single-glazing plate, were applied to the prototype. It was found that for both covers, the heat pipe fluid temperature rose dramatically at the start-up operation and afterwards remained a slow but steady growth; while the water temperature remained a steadily growing trend throughout the operational day. The temperature rise of the circulated water at 1.6. l/min of flow rate was around 13.5 °C in the double-glazed/evacuated tubes based system and 10 °C in the single-glazing based system; correspondingly, their average solar conversion efficiencies were 48.8% and 36%, and the COPs were 14 and 10.5 respectively. In overall, the double-glazed/evacuated tubes based system presented a better performance than the single glazing based one. © 2012 Elsevier Ltd.

Lu H.,Nanjing University of Information Science and Technology
Proceedings - 2015 International Conference of Educational Innovation Through Technology, EITT 2015 | Year: 2015

Controlling access to multimedia lecterns is an important yet complicated part of multimedia teaching management. Traditional measures are problematic in many ways. For instance, manual unlocking is human costly, ID cards issued to users often get lost. In order to solve these problems, this paper proposes to design a new type of access control system on the basis of the digitized campus. Integrated into, and interacting in real time, with the educational administration system, this system ensures that multimedia lecterns are accessible by means of campus cards only to specified teacher in the specified time and place, and makes remote management and information acquisition possible. © 2015 IEEE.

Lin G.,Nanjing Southeast University | Chen X.,Nanjing University of Information Science and Technology
Journal of Computers | Year: 2011

A method for robot indoor automatic positioning and orientating based on two-dimensional (2D) barcode landmark is proposed. By using the scheme of the 2D barcode for reference, a special landmark is designed which is convenient to operate and easy to recognize, contain coordinates of their absolute positions and have some ability to automatically correct errors. Landmarks are placed over the "ceiling" and photographed by a camera mounted on the robot with its optical axis vertical to the ceiling plane. The coordinates and angle of the landmark is acquired through image segmentation, contour extracting, characteristic curves matching and landmark properties identifying, and then the robot's current absolute position and heading angle is computed. The experiments proved the effectiveness of the method and shows that the method can meet accuracy requirements of indoor position and orientation. © 2011 ACADEMY PUBLISHER.

Wang T.,Nanjing Normal University | Wang T.,Nanjing University of Information Science and Technology | Wang M.,Nanjing Normal University
IEEE Photonics Technology Letters | Year: 2012

A Fabry-Pérot fiber sensor for the simultaneous measurement of refractive index (RI) and temperature based on an in-fiber ellipsoidal cavity is proposed. The sensor head consists of an ellipsoidal air-microcavity, which is formed by splicing together a single-mode fiber and a photonic crystal fiber with a simple arc-discharge technique. The external RI is determined through the analysis of the fast Fourier transform. The sensor is also capable of simultaneous measurement of temperature by tracking the wavelength shift. Easy fabrication, low-cost, and high-contrast make it appropriate for practical application. © 1989-2012 IEEE.

Liu H.,Shanghai Meteorological Center | Xue J.,Chinese Academy of Meteorological Sciences | Gu J.,Chongqing Meteorological Bureau | Xu H.,Nanjing University of Information Science and Technology
Advances in Atmospheric Sciences | Year: 2012

Constructing β-mesoscale weather systems in initial fields remains a challenging problem in a mesoscale numerical weather prediction (NWP) model. Without vertical velocity matching the β-mesoscale weather system, convection activities would be suppressed by downdraft and cooling caused by precipitating hydrometeors. In this study, a method, basing on the three-dimensional variational (3DVAR) assimilation technique, was developed to obtain reasonable structures of β-mesoscale weather systems by assimilating radar data in a next-generation NWP system named GRAPES (the Global and Regional Assimilation and Prediction System) of China. Single-point testing indicated that assimilating radial wind significantly improved the horizontal wind but had little effect on the vertical velocity, while assimilating the retrieved vertical velocity (taking Richardson's equation as the observational operator) can greatly improve the vertical motion. Experiments on a typhoon show that assimilation of the radial wind data can greatly improve the prediction of the typhoon track, and can ameliorate precipitation to some extent. Assimilating the retrieved vertical velocity and rainwater mixing ratio, and adjusting water vapor and cloud water mixing ratio in the initial fields simultaneously, can significantly improve the tropical cyclone rainfall forecast but has little effect on typhoon path. Joint assimilating these three kinds of radar data gets the best results. Taking into account the scale of different weather systems and representation of observational data, data quality control, error setting of background field and observation data are still requiring further in-depth study. © 2012 Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg.

Si D.,National Climate Center | Si D.,Nanjing University of Information Science and Technology | Ding Y.,National Climate Center
International Journal of Climatology | Year: 2012

The precipitation in China manifests a remarkable quasi-biennial signal. For interannual variability, about 70% stations over China indicate the dominance of a quasi-2-year period. The maximum precipitation variability associated with the quasi-biennial oscillation is located over the Yangtze River valley (YRV) and Huaihe River valley (HRV) as well as South China. This paper attempts to reveal the spatial-temporal evolution of the precipitation in China and related large-scale atmospheric circulation associated with the tropospheric biennial oscillation (TBO) in East Asia by using a season-dependent empirical orthogonal function (S-EOF) analysis approach. The leading two modes of the TBO of summer precipitation in China and associated large-scale circulations are examined by the S-EOF analysis and regression analyses based on the S-EOF time coefficients. The first TBO mode is characterized by an elongated band of positive precipitation anomalies along the YRV and negative precipitation anomalies over both North and South China. The second TBO mode is characterized by an elongated band of positive precipitation anomalies along the HRV and negative precipitation anomalies to the north of the Yellow River and to the south of the Yangtze River, respectively. Meanwhile, the leading modes of the TBO in East Asia may be determined by the meridional teleconnection Rossby wave pattern extending from the WNP to the midlatitudes of East Asia that is forced by the heating source fluctuation over the WNP during boreal summer. And the cold air activity, which is associated with the East Asian winter monsoon, may further influence the leading modes of the TBO through a modulation of the large-scale atmosphere circulation over East Asia during the following boreal summer. Also found is that the TBO in East Aisa depends on both the large-scale air-sea coupling over the tropical Indo-Pacific Ocean regions and the tropical-midlatitude interaction in the western North Pacific (WNP)-East Asia region. A fundamental element for the TBO in East Asia is the WNP monsoon. It is not only an important component of the TBO cycle in the tropics but also serves as a major source of the TBO signal for the subtropical East Asia. The meridional teleconnection Rossby wave train over the WNP-East Asia region acts as a conveyer belt that transports the tropical TBO signal to the midlatitudes of East Asia, and produces the TBO footprints in the large-scale circulation and precipitation in East Asia. Furthermore, the cold air activity over the East Asia during boreal summer also services as an important link in the chain events of the tropical-midlatitude interaction, with enhancing the role of the TBO modes in East Asia. © 2011 Royal Meteorological Society.

Wu X.,Nanjing University of Information Science and Technology | Wu X.,Iowa State University | Deng L.,Pacific Northwest National Laboratory
Journal of Climate | Year: 2013

The moist static energy (MSE) anomalies and MSE budget associated with the Madden-Julian oscillation (MJO) simulated in the Iowa State University General Circulation Model (ISUGCM) over the Indian and Pacific Oceans are compared with observations. Different phase relationships between MJO 850-hPa zonal wind, precipitation, and surface latent heat flux are simulated over the Indian Ocean and western Pacific, which are greatly influenced by the convection closure, trigger conditions, and convective momentum transport (CMT). The moist static energy builds up from the lower troposphere 15-20 days before the peak of MJOprecipitation, and reaches the maximum in the middle troposphere (500-600 hPa) near the peak ofMJO precipitation. The gradual lower-tropospheric heating and moistening and the upward transport of moist static energy are important aspects of MJO events, which are documented in observational studies but poorly simulated in most GCMs. The trigger conditions for deep convection, obtained from the year-long cloudresolving model (CRM) simulations, contribute to the striking difference between ISUGCM simulations with the original and modified convection schemes and play the major role in the improved MJO simulation in ISUGCM. Additionally, the budget analysis with the ISUGCM simulations shows the increase in MJO MSE is in phase with the horizontal advection of MSE over the western Pacific, while out of phase with the horizontal advection of MSE over the Indian Ocean. However, the NCEP analysis shows that the tendency of MJO MSE is in phase with the horizontal advection of MSE over both oceans. ©2013 American Meteorological Society.

Hu X.-M.,University of Oklahoma | Klein P.M.,University of Oklahoma | Xue M.,University of Oklahoma | Lundquist J.K.,University of Colorado at Boulder | And 3 more authors.
Journal of Applied Meteorology and Climatology | Year: 2013

Previous analysis of Oklahoma City (OKC), Oklahoma, temperature data indicated that urban heat islands (UHIs) frequently formed at night and the observed UHI intensity was variable (1°-4°C). The current study focuses on identifying meteorological phenomena that contributed to the variability of nocturnal UHI intensity in OKC during July 2003. Two episodes, one with a strong UHI signature and one with a weak signature, were studied in detail using observations along with simulations with the Weather Research and Forecasting model. Mechanical mixing associated with low-level jets (LLJs) played a critical role in moderating the nocturnal UHI intensity. During nights with weak LLJs or in the absence of LLJs, vertical mixing weakened at night and strong temperature inversions developed in the rural surface layer as a result of radiative cooling. The shallow stable boundary layer (SBL < 200 m) observed under such conditions was strongly altered inside the city because rougher and warmer surface characteristics caused vertical mixing that eroded the near-surface inversion. Accordingly, temperatures measured within the urban canopy layer at night were consistently higher than at nearby rural sites of comparable height (by ∼3°-4°C). During nights with strong LLJs, however, the jets facilitated enhanced turbulent mixing in the nocturnal boundary layer. As a consequence, atmospheric stability was much weaker and urban effects played a much less prominent role in altering the SBL structure; therefore, UHI intensities were smaller (<1°C) during strong LLJs. The finding that rural inversion strength can serve as an indicator for UHI intensity highlights that the structure of the nocturnal boundary layer is important for UHI assessments. © 2013 American Meteorological Society.

Zou X.,Florida State University | Qin Z.,Nanjing University of Information Science and Technology | Qin Z.,Florida State University | Weng F.,National Oceanic and Atmospheric Administration
Monthly Weather Review | Year: 2013

Satellite microwave humidity sounding data are assimilated through the gridpoint statistical interpolation (GSI) analysis system into the Advanced Research core of the Weather Research and Forecasting (WRF) model (ARW) for a coastal precipitation event. A detailed analysis shows that uses of Microwave Humidity Sounder (MHS) data from both NOAA-18 andMetOp-A results in GSI degraded precipitation threat scores in a 24-h model forecast. The root cause for this degradation is related to the MHS quality control algorithm, which is supposed to remove cloudy radiances. Currently, the GSI cloud detection is based on the brightness temperature differences between observations and the model background state attwo MHS window channels. It is found that the GSI quality control algorithm fails to identify some MHS cloudy radiancesin cloud edges where the ARW model has no cloud and the water vapor amount is low. A new MHS cloud detection algorithm is developed based on a statistical relationship between threeMHSchannels and the Geostationary Operational Environmental Satellite (GOES) imager channel at 10.7mm. The 24-h quantitative precipitation forecast is improved rather than degraded by MHS radiance data assimilation when the new cloud detection algorithm is added to the GSI MHS quality control process. The temporal evolution of 3-h accumulative rainfall distributions compared favorably with that of multisensor NCEP observations and GOES-12 imager observations. The precipitation threat scores are increased by more than 50% after 3-6 h of model forecasts for 3-h rainfall thresholds exceeding 1.0 mm © 2013 American Meteorological Society.

Zhao L.,Yale University | Lee X.,Yale University | Liu S.,Nanjing University of Information Science and Technology
Journal of Geophysical Research: Atmospheres | Year: 2013

Solar radiation at the Earth's surface is an important driver of meteorological and ecological processes. The objective of this study is to evaluate the accuracy of the reanalysis solar radiation produced by NARR (North American Regional Reanalysis) and MERRA (Modern-Era Retrospective Analysis for Research and Applications) against the FLUXNET measurements in North America. We found that both assimilation systems systematically overestimated the surface solar radiation flux on the monthly and annual scale, with an average bias error of +37.2 Wm-2 for NARR and of +20.2 Wm-2 for MERRA. The bias errors were larger under cloudy skies than under clear skies. A postreanalysis algorithm consisting of empirical relationships between model bias, a clearness index, and site elevation was proposed to correct the model errors. Results show that the algorithm can remove the systematic bias errors for both FLUXNET calibration sites (sites used to establish the algorithm) and independent validation sites. After correction, the average annual mean bias errors were reduced to +1.3 Wm-2 for NARR and +2.7 Wm-2 for MERRA. Applying the correction algorithm to the global domain of MERRA brought the global mean surface incoming shortwave radiation down by 17.3 W m-2 to 175.5 W m-2. Under the constraint of the energy balance, other radiation and energy balance terms at the Earth's surface, estimated from independent global data products, also support the need for a downward adjustment of the MERRA surface solar radiation. Key Points NARR and MERRA systematically overestimated the surface incoming solar radiationA simple post-reanalysis correction algorithm was proposedGlobal surface energy balance was revised according to the correction ©2013. American Geophysical Union. All Rights Reserved.

Qi Y.,University of Oklahoma | Qi Y.,Nanjing University of Information Science and Technology | Zhang J.,National Oceanic and Atmospheric Administration | Zhang P.,University of Oklahoma
Quarterly Journal of the Royal Meteorological Society | Year: 2013

A new convective/stratiform (C/S) precipitation segregation algorithm was developed for applications with single radar volume scan data and in its native (spherical) coordinates. The new algorithm consists of two parts: the first is to find convective rainfall cores based on physical characteristics of different rainfall types, and the second is to delineate the full convective area through seeded region growing. The new scheme takes into account radar sampling characteristics and a variety of precipitation scenarios where the C/S delineation was relatively challenging. The new C/S delineation scheme has two impacts on radar quantitative precipitation estimation (QPE): (i) correctly separate convective and stratiform regions such that appropriate Ze-R relationships can be applied; (ii) correctly define the stratiform area such that a vertical profile of reflectivity (VPR) correction can be applied. The VPR correction is very important to reduce overestimation errors in radar QPEs associated with bright band. The new algorithm was tested on many events and showed improved performance over previous schemes, especially when handling strong bright band and melting graupels in stratiform precipitation. The new scheme was also tested in radar quantitative precipitation estimation (QPE) and it consistently reduced the root mean square error and mean absolute bias in the radar QPE when compared with gauges. © 2013 Royal Meteorological Society.

He W.-P.,National Climate Center | Liu Q.-Q.,Nanjing University of Information Science and Technology | Jiang Y.-D.,National Climate Center | Lu Y.,Yangzhou Meteorological Office
Chinese Physics B | Year: 2015

In the present paper, a comparison of the performance between moving cutting data-rescaled range analysis (MC-R/S) and moving cutting data-rescaled variance analysis (MC-V/S) is made. The results clearly indicate that the operating efficiency of the MC-R/S algorithm is higher than that of the MC-V/S algorithm. In our numerical test, the computer time consumed by MC-V/S is approximately 25 times that by MC-R/S for an identical window size in artificial data. Except for the difference in operating efficiency, there are no significant differences in performance between MC-R/S and MC-V/S for the abrupt dynamic change detection. MC-R/S and MC-V/S both display some degree of anti-noise ability. However, it is important to consider the influences of strong noise on the detection results of MC-R/S and MC-V/S in practical application processes. © 2015 Chinese Physical Society and IOP Publishing Ltd.

Sallee J.-B.,British Antarctic Survey | Shuckburgh E.,British Antarctic Survey | Bruneau N.,British Antarctic Survey | Meijers A.J.S.,British Antarctic Survey | And 2 more authors.
Journal of Geophysical Research: Oceans | Year: 2013

The development of the deep Southern Ocean winter mixed layer in the climate models participating in the fifth Coupled Models Intercomparison Project (CMIP5) is assessed. The deep winter convection regions are key to the ventilation of the ocean interior, and changes in their properties have been related to climate change in numerous studies. Their simulation in climate models is consistently too shallow, too light and shifted equatorward compared to observations. The shallow bias is mostly associated with an excess annual-mean freshwater input at the sea surface that over-stratifies the surface layer and prevents deep convection from developing in winter. In contrast, modeled future changes are mostly associated with a reduced heat loss in winter that leads to even shallower winter mixed layers. The mixed layers shallow most strongly in the Pacific basin under future scenarios, and this is associated with a reduction of the ventilated water volume in the interior. We find a strong state dependency for the future change of mixed-layer depth, with larger future shallowing being simulated by models with larger historical mixed-layer depths. Given that most models are biased shallow, we expect that most CMIP5 climate models might underestimate the future winter mixed-layer shallowing, with important implications for the sequestration of heat, and gases such as carbon dioxide, and therefore for climate. © 2013. American Geophysical Union. All Rights Reserved.

Qin Z.,Nanjing University of Information Science and Technology | Zou X.,Florida State University | Weng F.,The Center for Satellite Applications and Research
Journal of Geophysical Research: Atmospheres | Year: 2013

The differences between brightness temperature observations and simulated observations based on numerical weather predictions, i.e., O-B, for Advanced Technology Microwave Sounder (ATMS) temperature sounding channels exhibit a clear striping pattern [Bormann et al., 2013]. We propose to first use the principal component analysis to isolate scan-dependent features such as the cross-track striping from the atmospheric signal and then to use an Ensemble Empirical Mode Decomposition (EEMD) to extract the striping noise in ATMS Earth scene brightness temperature observations for both temperature and water vapor sounding channels. It is shown that the Principal Component (PC) coefficient of the first PC mode, which mainly describes a scan-dependent feature of cross-track radiometer measurements, captures the striping noise. The EEMD is then applied to the PC coefficient to extract the first three high-frequency intrinsic mode functions (IMFs), which are denoted as the PC1/IMF3 noise. When the PC1/IMF3 noise is removed from the data, the striping noise is imperceptible in the global distribution of O-B for ATMS temperature sounding channels 1-16. Using the same method, it is demonstrated that the striping noise is also present in ATMS water vapor sounding channels 17-22. The magnitude of the ATMS striping noise is about ±0.3 K for the temperature sounding channels and ±1.0 K for the moisture sounding channels. The same technique is also applied to Advanced Microwave Sounding Unit-A (AMSU-A), AMSU-B, and Microwave Humidity Sounder (MHS). The striping noise is undetectable for AMSU-A but present in AMSU-B and MHS data. Key Points Striping noise is found not only in ATMS observations but also AMSU-B and MHS A new method is proposed for extracting the striping noise from the observations Same magnitude striping noise is found in Earth scene data and maneuver data ©2013. American Geophysical Union. All Rights Reserved.

Sun L.,Nanjing Southeast University | Cheng M.,Nanjing Southeast University | Jia H.,Nanjing University of Information Science and Technology
IEEE Transactions on Industrial Electronics | Year: 2015

A permanent-magnet dual-rotor motor is particularly suitable for constructing the power split device in hybrid electric vehicle application. This paper proposes a new magnetic-geared dual-rotor motor (MGDRM) design with complementary structure, in which both the inner and outer rotors are divided into three modules with a proper angular displacement for each other along the axis direction. This complementary design makes the flux linkage symmetrical and total cogging torque significantly reduced, without impairing the torque production. A simplified magnetic circuit model is developed to illustrate the complementary principle. By finite-element analysis (FEA), the effectiveness of such complementary structure is verified through the comparison with the conventional design. A prototype motor has been manufactured, and experiments have been carried out. Both FEA and experiments show that this new MGDRM offers symmetrical back-EMF waveforms, smaller cogging torque, and lower torque ripple. © 1982-2012 IEEE.

Kou L.,Nanjing University of Information Science and Technology | Xiang M.,CAS Institute of Electronics | Wang X.,CAS Institute of Electronics | Zhu M.,CAS Institute of Electronics
IET Radar, Sonar and Navigation | Year: 2013

Circular synthetic aperture radar (SAR) imaging on the geosynchronous orbit has significant potential advantages, such as high resolution three-dimensional imaging, large coverage, but it also has challenges to overcome. One major problem limiting the high-resolution geosynchronous circular SAR (GEOCSAR) performances is the atmospheric effects including the tropospheric and ionospheric effects. In this study, the authors mainly consider the tropospheric effects on L-band GEOCSAR imaging. Since the integration time of GEOCSAR may be as long as 24 h, and the coverage can reach 1/3 of the Earth's surface, the effects of the spatial and temporal variation of the tropospheric refractive index cannot be ignored if well focused images are to be obtained. The analysis shows that the temporal variation of the tropospheric refractive index may cause severe degradation of the SAR images; the spatial variation of the refractive index and the tropospheric turbulence are not the important factor limiting the GEOCSAR imaging performance. © The Institution of Engineering and Technology 2013.

Qian H.Y.,Nanjing University of Technology | Kong Q.G.,Nanjing University of Information Science and Technology | Zhang B.L.,Nanjing University of Technology
Powder Technology | Year: 2013

To investigate the effects of grinding media shapes on the grinding kinetics of ball mill cement clinker, the grinding effects with φ20. mm balls and φ20 × 20. mm cylinders on six different size fractions, i.e. -4.75 + 4.00. mm, -4.00 + 3.35. mm, -3.35 + 2.36. mm, -2.36 + 2.00. mm, -2.00 + 1.70. mm and -1.70 + 1.18. mm of cement clinkers, were studied in a laboratory scale ball mill. The specific rate of breakage and the primary breakage distribution function were compared for the balls and cylinders. Result shows that cement clinker obeys first-order grinding kinetics in the case of both balls and cylinders. The specific rate of breakage of cylinders is higher than that of balls. The primary breakage distribution parameters are dependent on the initial feed size. The φ value of cylinders is higher than that of balls. © 2012 Elsevier B.V.

Xiong J.-F.,Nanjing University of Information Science and Technology | Xiong J.-F.,Hohai University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

The interharmonics, either close to harmonics or fundamental wave, is the direct cause of voltage flicker, so interhammics detection has important significance for improving power quality. The limitations of windowed interpolation algorithm and spectral estimation method are analyzed with the consideration of the wide and multi-frequency characteristic in a real power network. An interharmonic detection algorithm is proposed based on the windowed interpolation and the Prony method. The interpolation method calculates each parameter of signals and frequency analysis method is used to identify the frequency interval in which two adjacent components and interhamonics are located, and then the Prony algorithm is used to compute residual components filtered by time domain. Matlab simulation shows that the new method has higher frequency resolution and is more precise than windowed interpolation algorithm, it need not estimate the numbers of signals and can eliminate the influence of pseudo-spectra.

Gu B.,Nanjing University of Information Science and Technology
Journal of the Optical Society of America B: Optical Physics | Year: 2012

We propose a single-photon-assisted entanglement concentration protocol (ECP) for nonlocal N-photon systems in a partially entangled pure W-class state with linear optical elements. Only one of the N parties in quantum communication prepares an ancillary photon and operates the entanglement concentration process for picking up the standard N-photon W state from each partially entangled pure W-class state by choosing the two-mode instances from a polarization beam splitter. Compared with other ECPs for W-class states, our protocol has some advantages. First, it requires only linear optical elements. Second, it requires an N-photon system and an ancillary photon for each round of concentration, not two systems. Third, only one party asks other parties to retain or discard their photons. All these advantages make our ECP more feasible and more convenient than others. © 2012 Optical Society of America.

Zhao J.S.,Chinese Academy of Sciences | Zhao J.S.,CAS National Astronomical Observatories | Wu D.J.,Chinese Academy of Sciences | Lu J.Y.,Nanjing University of Information Science and Technology | Lu J.Y.,National Center for Space Weather
Astrophysical Journal | Year: 2013

This study investigates the spectral structure of the kinetic Alfvén turbulence in the low-beta plasmas. We consider a strong turbulence resulting from collisions between counterpropagating wavepackets with equal energy. Our results show that (1) the spectra of the magnetic and electric field fluctuations display a transition at the electron inertial length scale, (2) the turbulence cascades mainly toward the magnetic field direction as the cascade scale is smaller than the electron inertial length, and (3) the parallel electric field increases as the turbulent scale decreases. We also show that the parallel electric field in the solar flare loops can be 102-10 4 times the Dreicer field as the turbulence reaches the electron inertial length scale. © 2013. The American Astronomical Society. All rights reserved..

Qi Y.,University of Oklahoma | Qi Y.,Nanjing University of Information Science and Technology | Zhang J.,National Oceanic and Atmospheric Administration | Zhang P.,University of Oklahoma | Cao Q.,University of Oklahoma
Journal of Geophysical Research: Atmospheres | Year: 2013

Vertical profile of reflectivity (VPR) correction of bright band (BB) effects has been a challenge for single-polarization radar quantitative precipitation estimations (QPEs) for mesoscale convective systems and for cool season stratiform precipitation when the freezing level is low. BB is often found in the radar observations of stratiform precipitation, and the inflated reflectivity intensities in the BB often cause positive biases in radar QPEs. A VPR correction is desirable to mitigate the BB contamination and reduce the bias. However, a well-defined BB bottom, while critical for an effective correction of the bias, is often not found in the VPRs. Fortunately, polarimetric radar variables, especially the copolar correlation coefficient (rHV), can provide a much better depiction of vertical BB structure than does reflectivity. In the current study, an apparent vertical profile of rHV (AVPrHV) correction scheme is developed. For each tilt of the radar volume scan data, the precipitation echoes are segregated into convective and stratiform regions. An apparent VPR (AVPR) and AVPrHV are computed for the stratiform region in the given tilt. Then the bright band top, peak, and bottom are identified from the AVPR and AVPrHV, and a linear VPR correction model is fit to the AVPR in the BB layer. VPR corrections are applied to the reflectivity field in the given tilt based on the linear correction model, and radar QPEs are derived from the corrected reflectivity field. The new AVPR and AVPrHV combined scheme was tested on two mesoscale convective system events and one cold season event in the United States and was shown to be more effective in reducing the radar QPE bias associated with the BB than did the AVPR correction alone. © 2013. American Geophysical Union. All Rights Reserved.

Murakami H.,University of Hawaii at Manoa | Li T.,University of Hawaii at Manoa | Li T.,Nanjing University of Information Science and Technology | Peng M.,U.S. Navy
Geophysical Research Letters | Year: 2013

This study uses the Meteorological Research Institute high-resolution Atmospheric Climate Model to determine whether environmental parameters that control tropical cyclone genesis in the Western North Pacific (WNP) and North Atlantic (NA) may differ in the global warming state. A box difference index was computed to quantitatively assess the role of environmental controlling parameters. The diagnosis of the model outputs shows that in the WNP, dynamic variables are of primary importance for separating developing and nondeveloping disturbances in the present-day climate, and such a relationship remains unchanged in a future warmer climate. This is in contrast to the NA, where box difference index increases for all dynamic variables investigated while it shows little change for thermodynamic variables. This implies that, when compared with the present-day climate in which thermodynamic variables have a major control on tropical cyclone genesis, dynamic and thermodynamic variables have equal control in the NA under the future warmer climate. © 2013 American Geophysical Union. All Rights Reserved.

Yang Y.,Lanzhou University | Chen X.,Lanzhou University | Qi Y.,Nanjing University of Information Science and Technology
Journal of Geophysical Research: Atmospheres | Year: 2013

In radar reflectivity observations, the convective and stratiform rain types always have poorly defined boundaries, which caused problem for rain classification. A fuzzy logic (FL) algorithm is developed to classify convective and stratiform rainfall based on the radar reflectivity observations in the next three steps: First, the algorithm is calibrated on Hefei Doppler radar site in China. Four features are selected based on a dataset for calibration, which spanned the period from 29 June to 23 July 2003; and the features basically represent a subjective choice of characteristics that are expected to distinguish different rain types. In the second step, membership functions are used to determine the degree to which each feature belongs to each rain type in the fuzzification process. Finally, the degree of fuzzification for each input feature is multiplied by predetermined weighting coefficients. The weighted degrees of the fuzzification are aggregated to produce a single value for each rain type. The aggregation can represent the possibility of classified rainfall type, and larger value reveals the higher potential for a particular class. The FL algorithm has been applied to four typical independent individual cases collected by Hefei Doppler radar, which have not been included in the database for calibration. Results show that the classification using the proposed FL algorithm is physically reasonable according to the analysis of three-dimensional radar reflectivity patterns, implying that the proposed FL algorithm has a great potential for the precipitation classification. Key PointsFL is flexible and capable of combining a variety of different input features.FL approach can express the classifications in a probabilistic way.FL algorithm can be an alternative method for precipitation classification. © 2013. American Geophysical Union. All Rights Reserved.

Lou W.,Xinchang Weather Bureau | Sun S.,Nanjing University of Information Science and Technology
Theoretical and Applied Climatology | Year: 2013

This paper proposes a method to design freezing damage policy-based agricultural insurance contracts for tea trees (an economic crop) in the Zhejiang Province of China, using a weather index. Data of economic losses caused by freezing damage, and the beginning dates of tea plucking (BDTP) from the Agricultural Bureau of each county in Zhejiang Province and tea planters, and meteorological observations were collected to establish the prediction model for BDTP, and to determine the relationship between economic loss rates caused by freezing damage at or before BDTP, and the minimum temperatures for "Wuniuzao," "Longjing-43," and "Jiukeng" teas. Based on the information diffusion theoretical model, occurrence probabilities of BDTP from 1 February to 20 April and lower temperatures at different levels are calculated. Then, the insurance premium rates of the three tea tree species can be estimated. Lastly, the tea tree freezing damage insurance contracts are designed, combining the advantages of regional yield-based index insurance and weather-based index insurance. © 2012 Springer-Verlag.

Sallee J.-B.,British Antarctic Survey | Shuckburgh E.,British Antarctic Survey | Bruneau N.,British Antarctic Survey | Meijers A.J.S.,British Antarctic Survey | And 3 more authors.
Journal of Geophysical Research: Oceans | Year: 2013

The ability of the models contributing to the fifth Coupled Models Intercomparison Project (CMIP5) to represent the Southern Ocean hydrological properties and its overturning is investigated in a water mass framework. Models have a consistent warm and light bias spread over the entire water column. The greatest bias occurs in the ventilated layers, which are volumetrically dominated by mode and intermediate layers. The ventilated layers have been observed to have a strong fingerprint of climate change and to impact climate by sequestrating a significant amount of heat and carbon dioxide. The mode water layer is poorly represented in the models and both mode and intermediate water have a significant fresh bias. Under increased radiative forcing, models simulate a warming and lightening of the entire water column, which is again greatest in the ventilated layers, highlighting the importance of these layers for propagating the climate signal into the deep ocean. While the intensity of the water mass overturning is relatively consistent between models, when compared to observation-based reconstructions, they exhibit a slightly larger rate of overturning at shallow to intermediate depths, and a slower rate of overturning deeper in the water column. Under increased radiative forcing, atmospheric fluxes increase the rate of simulated upper cell overturning, but this increase is counterbalanced by diapycnal fluxes, including mixed-layer horizontal mixing, and mostly vanishes. © 2013. American Geophysical Union. All Rights Reserved.

Bracegirdle T.J.,British Antarctic Survey | Shuckburgh E.,British Antarctic Survey | Sallee J.-B.,British Antarctic Survey | Wang Z.,Nanjing University of Information Science and Technology | And 4 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2013

An assessment of the fifth Coupled Models Intercomparison Project (CMIP5) models' simulation of the near-surface westerly wind jet position and strength over the Atlantic, Indian and Pacific sectors of the Southern Ocean is presented. Compared with reanalysis climatologies there is an equatorward bias of 3.3° (inter-model standard deviation of±1.9°) in the ensemble mean position of the zonal mean jet. The ensemble mean strength is biased slightly too weak, with the largest biases over the Pacific sector (-1.4±1.2 m/s, -19%). An analysis of atmosphere-only (AMIP) experiments indicates that 28% of the zonal mean position bias comes from coupling of the ocean/ice models to the atmosphere. The response to future emissions scenarios (RCP4.5 and RCP8.5) is characterized by two phases: (i) the period of most rapid ozone recovery (2000-2049) during which there is insignificant change in summer; and (ii) the period 2050-2098 during which RCP4.5 simulations show no significant change but RCP8.5 simulations show poleward shifts (0.33, 0.18 and 0.27°/decade over the Atlantic, Indian and Pacific sectors, respectively), and increases in strength (0.07, 0.08 and 0.15 m/s/decade, respectively). The models with larger equatorward position biases generally show larger poleward shifts (i.e. state dependence). This inter-model relationship is strongest over the Pacific sector (r =-0.91) and weakest over the Atlantic sector (r =-0.39). An assessment of jet structure shows that over the Atlantic sector jet shift is not clearly linked to indices of jet structure whereas over the Pacific sector the distance between the sub-polar and sub-tropical westerly jets appears to be important. © 2012. American Geophysical Union.

Shen C.,Anhui University of Science and Technology | Shen C.,Stanford University | Li G.,University of Alabama in Huntsville | Kong X.,University of Alabama in Huntsville | And 7 more authors.
Astrophysical Journal | Year: 2013

We report a multiple spacecraft observation of the 2012 May 17 GLE event. Using the coronagraph observations by SOHO/LASCO, STEREO-A/COR1, and STEREO-B/COR1, we identify two eruptions resulting in two coronal mass ejections (CMEs) that occurred in the same active region and close in time (∼2 minutes) in the 2012 May 17 GLE event. Both CMEs were fast. Complicated radio emissions, with multiple type II episodes, were observed from ground-based stations: Learmonth and BIRS, as well as the WAVES instrument on board the Wind spacecraft. High time-resolution SDO/AIA imaging data and SDO/HMI vector magnetic field data were also examined. A complicated pre-eruption magnetic field configuration, consisting of twisted flux-tube structure, is reconstructed. Solar energetic particles (SEPs) up to several hundred MeV nucleon-1 were detected in this event. Although the eruption source region was near the west limb, the event led to ground-level enhancement. The existence of two fast CMEs and the observation of high-energy particles with ground-level enhancement agrees well with a recently proposed "twin CME" scenario. © 2013. The American Astronomical Society. All rights reserved..

Fischer T.,University of Tubingen | Menz C.,Potsdam Institute for Climate Impact Research | Su B.,Nanjing University of Information Science and Technology | Scholten T.,University of Tubingen
International Journal of Climatology | Year: 2013

This study presents a detailed analysis of simulated and projected climate extremes in the Zhujiang River Basin (ZRB). Daily output from the regional climate model COSMO-CLM (CCLM), driven by the ECHAM5 general circulation model, is used. The hindcast simulation covers the period from 1961 to 2000 while the projection concentrates on the near future period from 2011 to 2050. Spatio-temporal statistical characteristics are investigated for three temperature and three precipitation indicators. The six simulated annual and monthly indicators are statistically compared with synoptic observations. The analysis is based on daily values of 195 grid points and 192 meteorological stations. The findings are presented and interpreted in terms of the model's capability. Compared to observations, slightly higher values for temperature indicators and slightly lower values for precipitation indicators are simulated. With the resulting good similarities in the spatial variation and trends, we conclude that CCLM is able to satisfyingly reproduce climate extreme for the simulated period. Therefore, our analyses show that CCLM can be used to project climate extremes in the ZRB for the period from 2011 to 2050. The projected changes indicate warmer and wetter conditions in the northern and southern regions, especially in winter and spring. This includes more intense rainfall events, which might potentially increase the risk of flooding in the central parts of the basin in these seasons. Warmer and dryer conditions can be expected in the western and eastern parts of the region, especially in summer and fall. These lower precipitation amounts but warmer temperatures will probably increase the evapotranspiration, which potentially leads to a higher risk of drought. Regarding these findings in climate extremes, adverse consequences in various sectors, such as agriculture, water, and energy should be anticipated. © 2013 Royal Meteorological Society.

Liu Z.,Nanjing University of Information Science and Technology | Ian H.,University of Macau
Chemical Physics Letters | Year: 2016

We employ a new quantum simulation approach to study the magnetism of nanodisks with Dzyaloshinsky-Moriya (DM) interaction. We find that a weak external magnetic field normal to the disk plane cannot obviously affect the single AFM skyrmion structure on small disk; but if it is sufficiently strong, it can destroy the AFM skyrmion completely. By increasing DM interaction, more self-organized magnetic domains appear, the average distance of the neighboring domains agrees well with a grid theory. In this case, a magnetic anisotropy normal to the disk plane can re-construct AFM skyrmion, providing a way for experimentalists to create AMF skyrmions. © 2016 Elsevier B.V. All rights reserved.

Ping F.,CAS Institute of Atmospheric Physics | Tang X.,CAS Institute of Atmospheric Physics | Luo Z.,Nanjing University of Information Science and Technology
Atmospheric Research | Year: 2013

A partitioning scheme based on surface rainfall processes is applied to a lag correlation analysis between tropical rainfall and its sources in this study. The rainfall sources include convective available potential energy (CAPE), water vapor source (water vapor convergence plus surface evaporation), and net condensation (condensation and deposition minus evaporation of rain). The analysis is carried out using a 21-day TOGA COARE cloud-resolving model simulation data. Maximum model domain mean surface rainfall leads the minimum mean CAPE by 6. h and is phase locking with the maximum mean net condensation mainly through the rainfall associated with water vapor convergence. Maximum mean surface rainfall lags the maximum mean water vapor source by 3. h mainly through the rainfall type associated with local atmospheric drying, water vapor divergence, and hydrometeor loss/convergence. © 2012 Elsevier B.V.

Liu Z.-S.,Nanjing University of Information Science and Technology | Sechovsky V.,Charles University | Divis M.,Charles University
Journal of Physics Condensed Matter | Year: 2011

For many years, micromagnetism and Monte Carlo simulation have served as the two main tools for studying the magnetic structures and physical properties of nanomagnets. However, the two approaches are based on classical physics, and thus lack the flexibility to deal with complex nanosystems, such as those of very tiny size or consisting of ions of different elements. To overcome the difficulty, a quantum simulation model has been proposed and a new computational algorithm developed in the present work. Both have been successfully applied to an assumed PrAl2 nanoparticle to study its magnetic behavior in external magnetic fields exerted along the crystal axes. The theoretical results obtained with the model and the new algorithm are reasonable physically and exhibit strong finite-size effects. The model can be generalized to study the magnetic configurations and physical properties of more complicated nanosystems, such as nanowires, nanotubes, etc. © 2011 IOP Publishing Ltd.

Chang J.,CAS Anhui Institute of Optics and Fine Mechanics | Chang J.,Nanjing University of Information Science and Technology | Mao Q.,CAS Anhui Institute of Optics and Fine Mechanics | Feng S.,CAS Anhui Institute of Optics and Fine Mechanics | And 2 more authors.
Optics Letters | Year: 2010

A wide tuning technique for mid-IR difference-frequency generation (DFG) with uniform grating periodically poled LiNbO3 (PPLN) is presented. Based on the dispersion property of the PPLN, the quasi-phase matching (QPM) band for the pump can evolve to two separate bands, and the spacing between them can be increased with the decrease of the crystal temperature. Two such separate QPM bands can be used for increasing the idler tuning range when the crystal temperature is set to adapt the pump tuning. With the technique, an idler tuning range of 690 nm is experimentally achieved with fiber laser fundamental lights. © 2010 Optical Society of America.

Liu Y.,Nanjing University of Information Science and Technology | Knopp G.,Paul Scherrer Institute | Qin C.,Henan Normal University | Gerber T.,Paul Scherrer Institute
Chemical Physics | Year: 2015

Ultrafast internal conversion dynamics of furan has been studied by femtosecond photoelectron imaging (PEI) coupled with photofragmentation (PF) spectroscopy. Photoelectron imaging of single-color multiphoton ionization and two-color pump-probe ionization are obtained and analyzed. Photoelectron bands are assigned to the related states. The time evolution of the photoelectron signal by pump-probe ionization can be well described by a biexponential decay: two rapid relaxation pathways with time constants of ∼15 fs and 85 (±11) fs. The rapid relaxation is ascribed to the ultrafast internal conversion (IC) from the S2 state to the vibrationally hot S1 state. The second relaxation process is attributed to the redistributions and depopulation of secondarily populated high vibronic S1 state and the formation of α-carbene and β-carbene by H immigration. Additionally, the transient characteristics of the fragment ions are also measured and discussed as a complementary understanding. © 2014 Elsevier B.V. All rights reserved.

Li C.,Ocean University of China | Zeng G.,Nanjing University of Information Science and Technology
Journal of Geophysical Research: Atmospheres | Year: 2013

The Yellow River loop valley (YRLV) is one of major agricultural production zones in many Chinese dynasties. Predicting rainfall variability in the YRLV is important for the society and the economy. This study demonstrates impacts of El Niño-Southern Oscillation (ENSO) on autumn rainfall in the YRLV based on statistical analyses of instrumental rainfall in China and reanalyzed SST and atmospheric data. Results indicate that the autumn rainfall anomaly in the YRLV may be partially controlled by the ENSO-like sea surface temperature (SST) pattern. The YRLV rainfall is below normal (above normal) in the El Niño (La Niña) developing years. This impact is mediated by an atmospheric response to the ENSO-like SST anomaly forcing via a westward Rossby wave. Furthermore, Niño3.4 index may be used as a factor for autumn rainfall in the YRLV region with a lead of 4-5 months. However, the relationship between the autumn YRLV rainfall and ENSO does not persist and has gone through decadal weakening since the end of 1980s via a decadal response of atmospheric circulation to ENSO. The decadal change of the relationship between the autumn YRLV rainfall and ENSO may be modulated by climate decadal shifts. ©2013. American Geophysical Union. All Rights Reserved.

Wang J.,Duke University | Wang J.,Nanjing University of Information Science and Technology
IEEE Transactions on Signal Processing | Year: 2015

Support recovery of sparse signals from compressed linear measurements is a fundamental problem in compressed sensing (CS). In this article, we study the orthogonal matching pursuit (OMP) algorithm for the recovery of support under noise. We consider two signal-to-noise ratio (SNR) settings: 1) the SNR depends on the sparsity level K of input signals, and 2) the SNR is an absolute constant independent of K. For the first setting, we establish necessary and sufficient conditions for the exact support recovery with OMP, expressed as lower bounds on the SNR. Our results indicate that in order to ensure the exact support recovery of all K-sparse signals with the OMP algorithm, the SNR must at least scale linearly with the sparsity level K. In the second setting, since the necessary condition on the SNR is not fulfilled, the exact support recovery with OMP is impossible. However, our analysis shows that recovery with an arbitrarily small but constant fraction of errors is possible with the OMP algorithm. This result may be useful for some practical applications where obtaining some large fraction of support positions is adequate. © 2015 IEEE.

Cao N.,Nanjing University of Information Science and Technology
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2015

This paper presents a new method about how to classify different types of aerosols by lidar measurements. Two lidar equations containing the optic parameters (backscatter coefficient, extinction coefficient) about two different types of aerosols, background aerosol and cloud, were built. The solutions about the two lidar equations, optic parameters inversion, were given to classify the background aerosol and cloud. The lidar signals generated from backscatter of two different types of aerosols, with two different extinction to backscatter coefficient ratio (Saer1, Saer2), were simulated, and the optic parameters inversion from the two simulated lidar signals were almost identical to the simulation parameters for different types of aerosols. Two types of aerosols, the background aerosol and cloud, were simultaneously measured by lidar, and were obviously discriminated by using this new method. The simulations and measurements results verified the new method for aerosols classifications. © 2015 SPIE.

Chen G.,Nanjing University of Science and Technology | Zhang W.-G.,Nanjing Southeast University | Zhang X.-N.,Nanjing University of Information Science and Technology
International Journal of Advanced Robotic Systems | Year: 2013

To overcome the drawbacks of using a traditional proportional-integral- derivative (PID) control method for a robot driver system, such as requiring preliminary offline learning, big overshoot and large speed fluctuation, a new method for speed tracking of a robot driver system based on sliding mode control is proposed in this paper. Firstly, the coordinated control model of multiple manipulators for the robot driver is built, which achieved coordinated control of the throttle mechanical leg, clutch mechanical leg, brake mechanical leg and shift mechanical arm for the robot driver. On the basis of this, a speed tracking sliding mode controller for a vehicle robot driver is designed using the method of multiple sliding surfaces design, and the variable structure control laws of throttle and brake are designed respectively, which realize the speed tracking of the given driving test cycle. Experimental results demonstrate that compared with the PID control method, the proposed method can obviously reduce the overshoot of vehicle speed tracking control and greatly improve the accuracy of vehicle speed tracking. The vehicle speed tracking accuracy stays within a tolerance band of ±2 km/h, which meets the requirements of national vehicle test standards. Furthermore, the action of the speed tracking control in the same driving test cycle using the proposed method is consistent, so that the robot driver has good repeatability. Therefore, it can ensure the effectiveness of the vehicle emission test. © 2013 Chen and Zhang.

Sui Y.,CAS Institute of Atmospheric Physics | Sui Y.,University of Chinese Academy of Sciences | Lang X.,CAS Institute of Atmospheric Physics | Lang X.,Nanjing University of Information Science and Technology | Jiang D.,CAS Institute of Atmospheric Physics
Climatic Change | Year: 2014

The signal of climate change is emerging against a background of natural internal variability. The time of emergence (ToE) is an indicator of the magnitude of the climate change signal relative to this background variability and may be useful for climate impact assessments. In this work, we examined the ToE of surface air temperature and precipitation over China under a medium mitigation scenario Representative Concentration Pathway 4.5 based on 30 satisfactory global climate models that are chosen from the Coupled Model Intercomparison Project Phase 5. Major conclusions are: the earliest ToE of annual and seasonal temperature occurs in the eastern Qinghai-Tibetan Plateau between 2006 and 2012 for S/N > 1.0 and between 2020 and 2030 for S/N > 2.0, which is 10-20 years sooner than in Northeast China where the latest ToE appears in the country. Consistent with previous studies at the global scale, the median ToE for most of China occurs sooner in summer (2008-2020 for S/N > 1.0 and 2020-2045 for S/N > 2.0), while for Northeast and North China the median ToE occurs sooner in autumn (2015-2025 for S/N > 1.0 and 2040-2050 for S/N > 2.0). For the ToE of temperature, the inter-model uncertainty is at least 24 years in all five regions of concern and more than 85 years in some seasons, and the inter-model uncertainty in one season for which the earliest median ToE occurs is the smallest among the seasons. For precipitation, the early ToE occurs in the northeastern Qinghai-Tibetan Plateau for the annual mean, and seasonally it occurs first in winter in northern Northeast China and southwestern Northwest China and in winter and spring in the northeastern Qinghai-Tibetan Plateau. For southern China, the median ToE will not occur until 2090. © 2014 Springer Science+Business Media Dordrecht.

Zhang H.,Nanjing University of Information Science and Technology | Zhang H.,University of Windsor | Wu Q.M.J.,University of Windsor | Nguyen T.M.,University of Windsor
IEEE Signal Processing Letters | Year: 2013

Fuzzy c-means (FCM) with spatial constraints has been considered as an effective algorithm for image segmentation. Student's t-distribution has come to be regarded as an alternative to Gaussian distribution, as it is heavily tailed and more robust for outliers. In this letter, we propose a new algorithm to incorporate the merits of these two approaches. The advantages of our method are as follows: First, we incorporate the local spatial information and pixel intensity value by considering the labeling of an image pixel influenced by the labels in its immediate neighborhood. Second, we introduce additional parameter a to control the extent of this influence. The larger a indicates heavier extent of influence in the neighborhoods. Finally, we utilize a mean template instead of the traditional hidden Markov random field (HMRF) model for estimation of prior probability. Compared with HMRF, our method is simple, easy and fast to implement. Experimental results on synthetic and real images demonstrate the improved robustness and effectiveness of our approach. © 1994-2012 IEEE.

Wang Q.,Nanjing University of Information Science and Technology
Journal of Power Electronics | Year: 2016

This paper presents a comprehensive analysis of the spurious turn-on phenomena in phase-shifted full-bridge (PSFB) converters. The conventional analysis of the spurious turn-on phenomenon does not establish in the PSFB converter as realizing zero voltage switching (ZVS). Firstly, a circuit model is proposed taking into account the parasitic capacitors and inductors of the transistors, as well as the parasitic elements of the power circuit loop. Second, an exhaustive investigation into the impact of all these parasitic elements on the spurio