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lagged response of phytoplanktonic photosynthetic competence to variation of nitrogen concentration in Jiaozhou Bay,China

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Chinese Journal of Oceanology and Limnology 2013年第6期31卷 1295-1305页

作者：付翔李凡吕振波翟红昌韩博平 Shandong Provincial Key Laboratory of Restoration for Marine Ecology Shandong Marine Fisheries Research Institute Second Institute of Oceanography SOA Institute of Hydrobiology Jinan University

Fluorescence-based maximal photochemical efficiency, Fv/Fm, is widely used as an indicator to photosynthetic competence in marine systems. It has been considered a useful parameter diagnosing the nutrient stress on phytoplankton photosynthesis, but many studies argue its usefulness. In the present study, we try to find a temporal relationship between Fv/Fm and nitrogen concentration, and provide a possible explanation on the controversy. We continuously measured Fv/Fm and nitrogen concentration once every 10 days from September 2003 to March 2004 at two stations in Jiaozhou Bay, northern China. It was found that Fv/ffm did not significantly correlate to synchronous nitrogen concentration, but the variation （i.e. the change between two adjacent cruises） of nitrogen concentration of the previous cruise and the variation ofFv/Fm of the current cruise were strongly correlated. This result indicates that a time lag exists between the variation of nutrient status and the subsequent Fv/Fm response. Length of the time lag seems just matched the interval of our measurements （10 days）. In the field, direct dependence of Fv/Fm on nitrogen concentration may not be found because of the lagged response of Fv/Fm to nitrogen concentration variations or physiological acclimation. Our results provide a possible way to explain the previously reported conflicting results on the relationship between Fv/Fm and nutrient status. To give a more-accurate estimate about the length of the time lag, an investigation that includes more frequent measurements is needed.

关键词： maximal photochemical efficiency nitrogen correlation analysis time lag phytoplankton

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Fuzzy Prediction of Silicon Content for BF Hot Metal

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Journal of Iron and Steel Research International 2005年第6期12卷 1-4页

作者： LI Qi-hui LIU Xiang-guan Zhejiang University Hangzhou 310027 China

Some key operation variables influencing hot metal silicon content were selected, and time lag of each of them was obtained. A standardized fuzzy system model was developed to approach the random nonlinear dynamic system of the change of silicon content, forecast the change of silicon content and calculate silicon content. The prediction of hot metal silicon content is very successful with the data collected online from BF No. 1 at Laiwu Iron and Steel Group Co.

关键词： hot metal silicon content time lag fuzzy prediction

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Detecting Agro-Droughts in Southwest of China Using MODIS Satellite Data

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Journal of Integrative Agriculture 2013年第1期12卷 159-168页

作者： ZHANG Feng ZHANG Li-wen WANG Xiu-zhen HUNG Jing-feng Institute of Agricultural Remote Sensing & Information Application Zhejiang University Key Laboratory of Environmental Remediation and Ecological Health Ministry of Education/College of Natural Resources and Environmental Science Zhejiang University Institute of Remote Sensing and Earth Sciences Hangzhou Normal University The Provinical Key Laboratories of Agricultural Remote Sensing and Information System Zhejiang Province

The normalized difference vegetation index （NDVI） has proven to be typically employed to assess terrestrial vegetation conditions. However, one limitation of NDVI for drought monitoring is the apparent time lag between rainfall deficit and NDVI response. To better understand this relationship, time series NDVI （2000-2010） during the growing season in Sichuan Province and Chongqing City were analyzed. The vegetation condition index （VCI） was used to construct a new drought index, time-integrated vegetation condition index （TIVCI）, and was then compared with meteorological drought indices-standardized precipitation index （SPI）, a multiple-time scale meteorological-drought index based on precipitation, to examine the sensitivity on droughts. Our research findings indicate the followings：（1） farmland NDVI sensitivity to precipitation in study area has a time lag of 16-24 d, and it maximally responds to the temperature with a lag of about 16 d. （2） We applied the approach to Sichuan Province and Chongqing City for extreme drought monitoring in 2006 and 2003, and the results show that the monitoring results from TIVCI are closer to the published China agricultural statistical data than VCI. Compared to VCI, the best results from TIVCI3 were found with the relative errors of -4.5 and 6.36% in 2006 for drought affected area and drought disaster area respectively, and 5.11 and -5.95% in 2003. （3） Compared to VCI, TIVCI has better correlation with the SPI, which indicates the lag and cumulative effects of precipitation on vegetation. Our finding proved that TIVCI is an effective indicator of drought detection when the time lag effects between NDVI and climate factors are taken into consideration.

关键词： time-integrated vegetation condition index (TIVCI) time lag normalized difference vegetation index (NDVI) drought monitor standardized precipitation index (SPI)

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带有时滞延迟的非线性抛物型微分方程的周期解

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Northeastern Mathematical Journal 1995年第3期11卷 285-296页

作者：王克

In this paper, the existence of periodic solutions of boundary value problem to nonlinear parabolic differential equations with bine lag is investigated, and some new applicable criteria are chined.

关键词： Periodic Solution nonlinear parabolic differential equation time lag Boundary Value Problem

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Analysis of unsteady supercavitating flow around a wedge

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Journal of Harbin Institute of Technology(New Series) 2009年第3期16卷 431-435页

作者：隗喜斌于开平邹平华邹经湘杨洪澜 School of Astronautics Harbin Institute of Technology School of Municipal and Environmental Engineering Harbin Institute of Technology

Supercavitating flow around a slender symmetric wedge moving at variable velocity in static fluid has been studied. Singular integral equation for the flow has been founded through distributing the sources and sinks on the symmetrical axis. The supereavity length at each moment is determined by solving the singular integral equation with finite difference method. The supercavity shape at each moment is obtained by solving the partial differential equation with variable coefficient. For the case that the wedge takes the impulse and uniformly variable motion, numerical results of time history of the supercavity length and shape are presented. The calculated results indicate that the shape and the length of the supercavity vary in a similar way to the case that the wedge takes variable motion, and there is a time lag in unsteady supercavitating flow induced by the variation of wedge velocity.

关键词： unsteady supercavitating integral equation method finite difference method time lag

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Groundwater Waves in a Coastal Fractured Aquifer of the Third Phase Qinshan Nuclear Power Engineering Field

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Journal of Shanghai Jiaotong university(Science) 2005年第4期10卷 441-445页

作者：周念清唐益群唐和平 Dept. of Geotechnical Eng. Tongji Univ. Shanghai 200092 China No.4 Research and Design Inst. of Nuclear Industry Shijiazhuang 050021

Tidal fluctuations of Hangzhou Bay produce progressive pressure waves in adjacent field fractured aquifers, as the pressure waves propagate, groundwater levels and hydraulic gradients continuously fluctuate. The effect of tidal fluctuations on groundwater flow can be determined using the mean hydraulic gradient that can be calculated by comparing mean ground and surface water *** fluctuation is shown to affect the piezometer readings taken in a nearshore fractured aquifer around the nuclear power engineering field. Continuous monitoring of a network of seven piezometers provided relations between the tidal cycle and the piezometer readings. The relations can be expressed in times of a time and amplitude scaling factor. The time lag and the tidal efficiency factor and wavelength are calculated using these parameters. It provides significant scientific basis to prevent tide and groundwater for the nuclear power engineering construction and safety run of nuclear power station in the future.

关键词： tidal fluctuation fractured aquifer hydraulic gradient time lag tidal efficiency factor nuclear power engineering

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Analysis of shock wave unsteadiness using space and time correlations applied to shadowgraph flow visualization data

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Advances in Aerodynamics 2019年第1期1卷 14-38页

作者： S.Marko P.M.Ligrani Propulsion Research Center Department of Mechanical and Aerospace EngineeringUniversity of Alabama in Huntsville5000 Technology DriveOlin B.King Technology Hall S236HuntsvilleAL 35899USA

Unsteady flow characteristics of a normal shock wave,a lambda foot,and a separated turbulent boundary layer are investigated within a unique test section with supersonic inlet *** supersonic wind tunnel facility,containing this test section,provides a Mach number of approximately 1.54 at the test section *** shadowgraph flow visualization data are employed to visualize shock wave structure within the test *** data are analyzed to determine shock wave unsteadiness characteristics,including grayscale spectral energy variations with frequency,as well as time and space correlations,which give coherence and time lag properties associated with perturbations associated with different flow *** illustrate the complexity and unsteadiness of shock-wave-boundary-layerinteractions,including event frequencies from grayscale spectral energy distributions determined using a lagrangian approach applied to shock wave location,and by grayscale spectral energy distributions determined using ensemble-averaging applied to multiple closely-located stationary pixel ***-correlation function results and two-point correlation functions(in the form of magnitude squared coherence)quantify the time-scales of periodic events,as well as the coherence of flow perturbations associated with different locations,over a range of *** time lag data provide information on the originating location of perturbation events,as well as the propagation direction and event sequence associated with different flow *** insight into spatial variations of time lag and flow coherence is provided by application of magnitude squared coherence analysis to multiple locations,relative to a single location associated with the normal shock wave.

关键词： Shock wave Supersonic flow time correlation Spatial correlation Autocorrelation Two-point correlation Frequency spectra Magnitude squared coherence time lag lagrangian flow analysis Unsteady flow analysis

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Study on snowmelt runoff simulation in the Kaidu River basin

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Science China Earth Sciences 2007年第S1期 26-35页

作者： ZHANG YiChi1, LI BaoLin1, BAO AnMing2, ZHOU ChengHu1, CHEN Xi2 & ZHANG XueRen3 1 Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China 2 Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences,ürümqi 830011, China 3 Xinjiang Tarim River Basin Management Bureau, Korla 841000, China

Alpine snowmelt is an important generation mode for runoff in the source region of the Tarim River basin, which covers four subbasins characterized by large area, sparse gauge stations, mixed runoff supplied by snowmelt and rainfall, and remarkably spatially heterogeneous precipitation. Taking the Kaidu River basin as a research area, this study analyzes the influence of these characteristics on the variables and parameters of the Snow Runoff Model and discusses the corresponding determination strategy to improve the accuracy of snowmelt simulation and forecast. The results show that: (i) The temperature controls the overall tendency of simulated runoff and is dominant to simulation accuracy, as the measured daily mean temperature cannot represent the average level of the same elevation in the basin and that directly inputting it to model leads to inaccurate simulations. Based on the analysis of remote sensing snow maps and simulation results, it is reasonable to approximate the mean temperature with 0.5 time daily maximum temperature. (ii) For the conflict between the limited gauge sta-tion and remarkably spatial heterogeneity of rainfall, it is not realistic to compute rainfall for each elevation zone. After the measured rainfall is multiplied by a proper coefficient and adjusted with runoff coefficient for rainfall, the measured rainfall data can satisfy the model demands. (iii) Adjusting time lag according to the variation of snowmelt and rainfall position can improve the simulation precision of the flood peak process. (iv) Along with temperature, the rainfall increases but cannot be completely monitored by limited gauge stations, which results in precision deterioration.

关键词： snowmelt runoff model (SRM) Kaidu River basin runoff simulation runoff coefficient for rainfall time lag

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Study of Construction Techniques and Hygro-Thermal Behavior of a Vernacular Earth Building in a Humid Tropical Climate

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Journal of Building Construction and Planning Research 2023年第3期11卷 69-85页

作者： Mouhamadou Nabi Kane Mapathe Ndiaye Emilie Pinard University College of Architecture Dakar (CUAD) University of Thies Thies Senegal Laboratory of Mechanics and Modeling University of Thies Thies Senegal McEwen School of Architecture Laurentian University Sudbury Canada

This study analyzes the know-how of local communities, to draw on techniques that make contemporary buildings more energy efficient. The impluvium hut in the locality of Enampore, Casamance, Southern Senegal, served as the object of study. The hut, including several rooms, is entirely built with earthen walls, earthen floor, earthen ceiling, covered by a double straw roof and its central courtyard. A room noted (L) and a semi-opened living space were chosen as spaces for hygro-thermal experimentation. The hottest average temperature obtained respectively in the room (L) and in the living space is 25.5˚C and 27˚C when outside is about 34˚C. The thermal amplitude inside room (L) is 0.88˚C, in semi-opened living space, is 2.6˚C and outside is 9.5˚C. With these results we can say that room (L) undergoes very low temperature variations and that there is no need to air-condition in the enclosure. The thermal amplitude makes it possible to see the influence of the earthen walls on the interior temperature and its regularity compared to the fluctuation of the external temperature. The thermal inertia of the building walls was characterized using also the time lag and the decrement factor. They was respectively 7.0 H and 0.093 for the room (L). With this result we can say that this material has a high thermal inertia. For humidity, it is high around 78.5% in the room (L), 66.0% at the semi-open living room, when it is 59.0% outside. Through this study, it is possible that the revalorization of vernacular architecture can be an alternative to reduce the energy consumption of buildings.

关键词： time lag Decrement Factor Thermal Inertia Double Skin Impluvium

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Nitrate in groundwater and the unsaturated zone in(semi)arid northern China:baseline and factors controlling its transport and fate

Nitrate in groundwater and the unsaturated zone in(semi)arid...

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中国科学院地质与地球物理研究所2013年度（第13届）学术年会

作者： Tianming Huang Zhonghe Pang Lijuan Yuan Key Laboratory of Engineering Geomechanics Institute of Geology and GeophysicsChinese Academy of Sciences

Knowledge of the baseline of groundwater nitrate is essential for water quality *** largescale anthropogenic activities,especially utilization of chemical fertilizers began from the 1950s in most countries, such as China,the baseline of groundwater nitrate can be determined from pre-modern water using tritium and statistical *** the(semi)arid northern China,the median values of nitrate baseline for the three large regions(Tarim river basin,TRB;Loess Plateau of China,LPC;North China Plain,NCP) range from 2 to 9 mg/L(as NO3).Several main factors control nitrate content in the unsaturated zone moisture and in groundwater,e.g.,nitrate input,sediment moisture movement(direction and rate),and depth of water table at the macroscopic scale in(semi)arid areas,where nitrate loss by denitrification can be *** unsaturated zone profiles(638 sediment samples in total) with depths ranging from 5 to 18.25 m were sampled to demonstrate how those factors affect groundwater *** sediment moisture moves upward from the water table in the TRB case,a large inventory of nitrate in the unsaturated zone with evapo-transpired origin would never enter groundwater and groundwater nitrate contents remain at the baseline *** the contrary,in the LPC and NCP,nitrate from fertilizers may pass through the unsaturated zone and eventually reach the water table to pollute *** is also noticed that there is a time lag between land-use change and groundwater quality response,due to the buffering capacity of the thick unsaturated zone,to which attention should be paid regarding water quality management.

关键词： Unsaturated zone profile Nitrate Arid area Northern China Baseline quality time lag

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