1991-2006年无锡市土地利用变化动态度及转换参数分析

在RS和GIS技术支持下,以3期TM/ETM+影像为数据源,提取无锡市土地利用变化信息,分析了区域土地利用变化的动态度;挖掘土地利用转移矩阵中的净变化量、交换变化量以及变化持续性等隐藏属性;在此基础上,通过随机转换和系统转换判别15 a间不同地类间转换的优势度,进一步探讨其对太湖流域生态环境的影响。结果表明:1991—2006年间无锡市建设用地面积呈现较快增长,而林地的流失速率最高;耕地主导了交换变化量,主要表现为空间位置转移;建设用地变化主导了净变化,其变化以建设用地新增为主;从期望新增量和期望流失量角度分析可知,林地转化为新增耕地具有明显的转换优势,同时又存在部分耕地转回林地的现象,两种地类间存在剧烈的空间位移,加剧了林地景观的破碎化程度。保护好现存林地和建设环太湖森林植被缓冲带有利于减轻农地面源污染和改善湖泊水质。

紫花苜蓿碳水通量日变化对土壤水分处理的响应

采用透明通量箱连接Li-6400光合作用系统的方法,研究了不同土壤水分处理条件下(自然降水+人工灌溉(PRAW)、自然降水(PRCP)和干旱(DROU))紫花苜蓿群体水平上碳水交换特征变量(生态系统净碳交换(NEE)、生态系统蒸散(ET)、水分利用效率(WUE)、生态系统呼吸(Rec)o)的日变化特征及其与环境因子(光合有效辐射(PAR)、土壤温度(T)s、冠层温度(T)c、空气温度(T)a和相对湿度(RH))之间的关系。结果表明:PRAW和PRCP之间的WUE(NEE,ET)日变化差异不显著;PRCP和DROU之间的WUE(NEE)日变化差异显著;PRAW和DROU之间的WUE(ET)日变化差异显著;3种土壤水分处理之间,Reco日变化差异均达显著水平。与PRCP相比,PRAW明显增大了植物对光能的利用效率(初始表观量子效率α),使得Ts成为影响ET日变化的主要因素,且减小了Ts对Reco的影响;与PRCP相比,DROU条件下,NEE与ET显著正相关,在PAR和Tc一定的条件下,随Ta增加ET呈显著线性减小趋势,另外,Reco仅与Tc呈极显著指数增长关系。

防城港东湾纳潮量减弱及其影响分析

【目的】研究防城港东湾水交换改变状况,分析其变化的原因,并探讨造成的影响。【方法】采用传统方法计算防城港东湾2008年和2012年的纳潮量。【结果】2008年防城港东湾纳潮量为1.8443×108 m3,2012年纳潮量为1.7436×108 m3,仅4年时间防城港东湾纳潮减少量占总纳潮量的5.5%。纳潮量减少后海水交换能力明显减弱。【结论】港口码头工程填海和岸线及滩涂资源的大量利用减少了湾内海域空间面积,造成海水交换能力减弱,使湾内海洋生态环境出现退化现象。

南京江北新区地表覆盖监测与分析

地表覆盖是自然环境要素的重要组成部分,其空间分布信息能反映人类社会经济活动的过程。以南京江北新区地理国情监测数据和基本统计成果为基础,采用地表覆盖转移矩阵、地表覆盖净变化与交换变化、变化动态度等方法对地表覆盖变化情况进行监测分析,综合评估江北新区目前的建设进程、效果和规划实施情况。

Tempo-Spatial Variations in Stomatal Conductance, Aperture and Density of Ligustrum sinense Acclimated to Different Light Environments

There was heterogeneous distribution in stomatal conductance (g-s) and stomatal aperture for both high- and low-light leaves of Ligustrum sinense Lour. in four designated positions within a leaf. Linear or exponential or polynomial relationships between g-s and stomatal aperture were found when regression of g-s and stomatal aperture was established. Statistical analysis revealed that the relationship between g-s and stomatal aperture for high-light leaves was more significant than that of low-light leaves. A linear relationship between g-s and stomatal aperture existed in both positions 1 and 3 for both high- and low-light leaves. The stomatal density of the low-light leaves was much lower than that of the high-light leaves. The sensitivity of stomata to changing environment for high-light leaves was higher than that for low-light leaves, which may also relate to the higher stomatal density for the high-light leaves.

Changes of Gas Exchanges in Leaves of Different Cultivars of Winter Wheat Released in Different Years

Three winter wheat cultivars ( Triticum aestivum L.), representatives of those widely cultivated in Beijing over the past six decades, were grown in the same environmental condition, and their physiological features were investigated. Daily changes of net photosynthetic rate (P-n), transpiration (T-r) in different growth stages were measured in order to find the relationship between leaf photosynthesis and yield. Instantaneous water use efficiency (WUE) of leaf was calculated from P-n/T-r. It is suggested that relationship between photosynthetic rate and yield changed with the developing stages of wheat. High yield wheat cultivar Jingdong 8 (released in the 1990s) had a higher photosynthetic rate ( the maximal P-n increased by 77%) and transpiration rate (the maximal T-r increased by 69%), but a lower WUE than the low yield cultivar Yanda 1817 (released in the 1940s) during the day time at stem elongation stage. However; difference of P-n among the three cultivars changed with wheat growth process. Before 10 o'clock P-n in leaves of Jingdong 8 usually was the highest of the three cultivars, but P-n of Yanda 1817 was the highest after 10 o'clock. At dough ripe stage, P-n in leaves of Yanda. 1817 was the highest among the three cultivars during the whole day. The difference of changing trend of transpiration in three wheat cultivars was similar to P,, but WUE of Yanda 1817 was the highest in those three cultivars, indicating that the higher yield of Jingdong 8 was achieved via a greater consumption of water. Contrary to the cultivars released in the later period, midday depression of photosynthesis was small in Yanda 1817, which might suggest that Yanda 1817 was resistant to photoinhibition. It is possible that photosynthetic potential in leaves of wheat increased as wheat cultivars was improved over the past six decades. However, it became less resistant to photoinhibition.

Seasonal variability of salinity budget and water exchange in the northern Indian Ocean from HYCOM assimilation

Based on HYbrid Coordinate Ocean Model (HYCOM) assimilation and observations, we analyzed seasonal variability of the salinity budget in the southeastern Arabian Sea (AS) and the southern part of the Bay of Bengal (BOB), as well as water exchange between the two basins. Results show that fresh water flux cannot explain salinity changes in salinity budget of both regions. Oceanic advection decreases salinity in the southeastern AS during the winter monsoon season and increases salinity in the southern BOB during the summer monsoon season. In winter, the Northeast Monsoon Current (NMC) carries fresher water from the BOB westward into the southern AS; this westward advection is confined to 4°-6°N and the upper 180 m south of the Indian peninsula. Part of the less saline water then turns northward, decreasing salinity in the southeastern AS. In summer, the Southwest Monsoon Current (SMC) advects high-salinity water from the AS eastward into the BOB, increasing salinity along its path. This eastward advection of high-salinity water south of the India Peninsula extends southward to 2°N, and the layer becomes shallower than in winter. In addition to the monsoon current, the salinity difference between the two basins is important for salinity advection.

Quantum Phase Transitions and Dimerized Phases in Frustrated Spin Ladder

In this paper, we study the phase diagram of a frustrated spin ladder model by applying the bosonization technique and the density-matrix renormalization-group （DMRG） algorithm. Effect of the intra-ehain next-nearest- neighbor （NNN） super-exchange interaction is investigated in detail and the order parameters are calculated to detect the emergence of the dimerized phases. We find that the intra-chain NNN interaction plays a key role in inducing dimerized phases.

Relationship Between Outdoor and Indoor Ozone Pollution Concentration

This paper analyses the changing rule of indoor ozone concentration and its influencing factors.A formula of indoor-outdoor concentration ratio(I/O ratio) was deduced based on the indoor ozone mass-balance equation.The ozone I/O ratio in different kinds of buildings was studied.Results show that I/O ratio is much related to air-exchange rate,which is well compatible with the theoretical calculation results.

A New Type of Seiberg-Witten Map and Its Application

Deformation quantization is a powerful tool to deal with systems in noncommutative space to get their energy spectra and corresponding Wigner functions, especially for the ease of both coordinates and momenta being noneommutative. In order to simplify solutions of the relevant .-genvalue equation, we introduce a new kind of Seiberg Witten-like map to change the variables of the noncommutative phase space into ones of a commutative phase space, and demonstrate its role via an example of two-dimensional oscillator with both kinetic and elastic couplings in the noneommutative phase space.

A HYDROGEN BONDING ASSISTED CATALYST SCREENED OUT VIA COMBINATORIAL CHEMISTRY STRATEGY

Possibilities for enhancement of catalytic reaction rate by combining phase transfer catalysis and hydrogen bonding of the catalyst with the substrate and reagent were studied. A phase transfer catalyst library with sixty polystyrene-supported quaternary ammonium salt catalysts was synthesized. The reduction of acetophenone by NaBH, was used as the probing reaction to select out the most active catalyst in the library by using iterative method, which was the gel-type triethanolamine aminating strongly basic anion exchange resin with the crosslinking degree of 2% A hydrogen bonding assisted catalytic mechanism was proposed to explain the high catalytic activity of the catalyst.

Matrix Expression of the Orthogonal Wavelet (Packets) Transform

Matrix expression of finite orthogonal wavelet transform of finite impulse response signal is more valuable for theoretical analysis and understanding. However, clear deduction for matrix expression has not been provided yet. In this paper, the formulation to generate the re-lated matrix is put forward and the theorem on the orthogonality of this matrix proved. This effort deploys a basis for more deeper and wider applications in chemical processes. *

Study of Contact Melting Inside Isothermally Heated Vertical Cylindrical Capsules

Close-contact melting processes of phase change material (PCM) inside vertical cylindrical capsule are studied. PCM are heated by the capsule isothermally at the bottom and side. The theoretical formulas of the melting rate and thickness of liquid layer during the heat transfer process are obtained by analysis, which are convenient for engineering predictions. Finally, the factors that affect melting are discussed, and conclusions are drawn.

Deformation quantization and noncommutative black holes

This short paper is based on the talk on the conference Operator Algebras and Related Topics held on July 23-27, 2010, Beijing. The author surveys recent developments of the noncommutative gravity in joint works with Chaichian, Tureanu, Sun, Wang, Xie and Zhang.

Rational Structure of X(N) over Q and Explicit Galois Action on CM Points

This paper reviews a less known rational structure on the Siegel modular variety X（N） = F（N）／Hg over Q for integers g, N ≥ 1. The author then describes explicitly how Galois groups act on CM points on this variety. Finally, another proof of the Shimura reciprocity law by using the result and the q-expansion principle is given.

On the Stability Analysis of Switched Nonlinear Systems with Time Varying Delay Under Arbitrary Switching

This paper addresses the stability problem for a class of switched nonlinear time varying delay systems modeled by delay differential equations. By transforming the system representation under the arrow form and using a new constructed Lyapunov function,the aggregation techniques,the Borne-Gentina practical stability criterion associated with the properties, new delay-independent stability conditions of the considered systems are established. Compared with the existing results in this area, the obtained result is explicit, simple to use and allows us to avoid the problem of searching a common Lyapunov function. Finally, an example is provided, with numerical simulations,to demonstrate the effectiveness of the proposed method.

Energy exchange of an alpine grassland on the eastern Qinghai-Tibetan Plateau

The seasonal variability in the surface energy exchange of an alpine grassland on the eastern Qinghai- Tibetan Plateau was investigated using eddy covariance measurements. Based on the change of air temperature and the seasonal distribution of precipitation, a winter season and wet season were identified, which were separated by transitional periods. The annual mean net radiation （Rn） was about 39 % of the annual mean solar radiation （Rs）. Rn was relatively low during the winter season （21% of Rs） compared with the wet season （54 % of Rs）, which can be explained by the difference in surface albedo and moisture condition between the two seasons. Annually, the main consumer of net radiation was latent heat flux （LE）. During the winter season, sensible heat flux （H） was dominant because of the frozen soil condition and lack of precipita- tion. During the wet season, LE expended 66 % of Rn due to relatively high temperature and sufficient rainfall cou- pled with vegetation growth. Leaf area index （LAI） had important influence on energy partitioning during wet season. The high LAI due to high soil water content （θv） contributed to high surface conductance （go） and LE, and thus low Bowen ratio （β）. LE was strongly controlled by Rn from June to August when gc and θv were high. During the transitional periods, H and LE were nearly equally parti- tioned in the energy balance. The results also suggested that the freeze-thaw condition of soil and the seasonal distribution of precipitation had important impacts on the energy exchange in this alpine grassland.

A New Method for Analyzing Heat Exchangers- Matching of Temperature Field

In heat exchangers, the magnitude of Nu of each duct is influenced by the temperature field, since the ratio of heat capacity rate will influence the matching status of the temperature field between contacting ducts, the total heat transfer coefficient is related with the ratio of heat capacity rate. Considering this relationship, a new method for analyzing heat exchanger is proposed - matching of temperature field. First, for a single duct with the temperature field varying exponentially along the flow direction, its Nu is calculated. Then under the hypothesis that the thermal resistance of the wall is negligible, the matching condition was set like this: both the temperature and heat flux are equal for the hot and cold fluids at the wall, so the matching relationship of parameter that describes the temperature field of the hot and cold fluids, was obtained. Finally the relationship between the total Nu and the ratio of heat capacity rate along with the ratio of inherent thermal resistance is obtained. Compared with traditional analyzing methods, the temperature matching method can be used to get the total heat transfer coefficient directly, and also be used for optimization of heat exchanger design. For a parallel flow, the optimal ratio of heat capacity rate is reciprocal to the ratio of inherent thermal resistance, and for a counter flow, the optimal ratio of heat capacity rate is zero or infinity.