Table of Content

20 July 2009, Volume 45 Issue 4

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Stability Analysis of a P2P Overlay Maintenance Protocol

FENG Wangsen,CHEN Ping,ZHANG Bei

2009, 45(4):  589-593. 

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The stability of basic leafset protocol is analyzed, which is a P2P overlay maintenance protocol. By analyzing the protocol behavior, it proves that the overlay topology must reach steady states after running the protocol for finite time and the final topology is one of the three types: ring, loopy and partitioned. This conclusion is also in accordance with the experimental results of basic leafset protocol.

Filtering of Ultra-Low Electromagnetic Detection Signal Using Independent Component Analysis

LI Peijun,JIN Huiran,SONG Benqin

2009, 45(4):  621-627. 

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The independent component analysis (ICA) was introduced for the filtering of the ultra-low electromagnetic (ULEM) detection curves. Simulated datasets were first used to validatethe effectiveness of ICAin the filtering. The real datasets were then used to evaluate and comparethe performance of the proposed filtering method. The results show that filtering of the ULEMsignals based on ICAis feasible. Moreover, the proposed filtering method could effectively suppress the noise and enhance the valuable features of the curves, which facilitates geological interpretation of the resulting curves. Some issues are also discussed.

A Profit-Driven Algorithm for Semantic Code Motion

NIE Jiutao,CHENG Xu

2009, 45(4):  599-606. 

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The potential reasons of negative effects of aggressive code motion were analyzed. The authors built the profit model and proposed a profit-driven semantic code motion algorithm, which determined if an existing result should be reused. The new algorithm was i mplemented in GCC-4.2.0. The experimental results achieved from SPEC2000 on an X86 machine show that the code generated by the GCC using the new algorithmis 6.8% and 2.6% faster on average than that using semantic code motion and that using the GCCs original code motion algorithm GVNPRE .

RiTLB: iTLB Design Based on Memory Region Reusing

XIE Jinsong,TONG Dong,LI Xianfeng,PANGJiufeng,WANG Keyi,CHENG Xu

2009, 45(4):  607-615. 

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In order to design iTLB by memory region reusing, its comparison bits of lookup are reduced through the memory region encoding technology firstly, which encodes the higher-order bits of VPN with a very shorter memory region ID before the VPNis sent to iTLB. Secondly, the memory region IDis reused before the next memory region is switched into. Compared to the baseline iTLB, experimental results show the average dynamic power, delay and area of the new design decrease by 62.84%, 9.96% and 44.78% respectively, with only 0.23% average IPC reduction.

Preliminary Studies on Global Geospatial Information Geocode Model and Application

CHENG Chengqi,SONG Shuhua

2009, 45(4):  663-667. 

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In order to resolve the data sharing caused by different code for the same geospatial object and the geospatial object code having no level information, a global geospatial information unique geocode model, GeoDNA, was put forward based on the global subdivision grid and the models architecture to express global continuous and multi-level geospatial information. At last, an example of encoding remote sensing image data was given. The results show that GeoDNA on global geospatial information enhances the information sharing capacity in GIS and improves the global massive data storage and management more effectively, which is of theoretical and applied value in regional emergency response.

Study on Wellbore Collapse Using the Theory and Method of Stability

YIN Youquan,CHEN Zhaowei

2009, 45(4):  559-564. 

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The analytical solutions for stress and displacement around a borehole during drilling were given. On the base of the solutions, the balance path curve for pressure and displacement at the face of the wellbore was drawn. The conclusion is that wellbore collapse is an instability phenomenon of extreme point type, and a number of issues in oil industry are clarified. At last, the formula of critical pressure for wellbore collapse is derived, and the condition for air and gas drilling is analyzed.

Body State Esti mationin a Quasi-Passive Bipedal Robot during Dynamic Walking

HUANG Yan,XIE Guangming,YANG Xiaohua,WANG Qining,WANG Long

2009, 45(4):  565-571. 

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The authors present a body state estimator for a quasi-passive bipedal robot with dynamic gaits, to estimate the key performance parameters of the robot during stable walking motion. Based on the traditional inertial measurement unit, this approach integrates accurate pitch and roll measurement result to correct the impact for acceleration by gravity, in order to improve the performance of the body state estimator. The method implements the estimation procedure off-line, using data extracted from various repeated walking motion of the robot and evaluates its performance with reference to a visual ground-truth measurement system. Satisfactory results are obtained by using body state estimator to analyze both robot walking and human walking. The results can be used as feedback to improve the stability of the walker.

Specifying Workflow Process and Describing Workflow Pattern Using Extended Place Net

HUANG Yu,HU Wenhui,ZHANG Shikun

2009, 45(4):  572-578. 

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The authors present a more novel Petri-net-based model featured by places with new properties to specify workflow process and represent advanced workflow patterns, and propose a newpattern named parameterized pattern. In the model, through distinguishing transitions fromroutings, place and transition are ableto represent actions of engine andtask respectively. Since the classical token-game semantic behavior of a Petri net-based workflow model is not suitable for describing the behavior of workflow process, the semantics of extended-place-net-based model with STfiring rules is given to capture and simulate workflow behavior.

Segmentation of Fingerprint I mages Using Discri minant Analysis of Multiple Features

CHEN Xiaoguang,FENG Jufu

2009, 45(4):  579-584. 

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A novel algorithmusing discriminant analysis of multiple features (DAMF) is presented for adaptive fingerprint image segmentation. Three block-level features includingthe variance，the orientation coherence measure and the total variation are used by the proposed method. For a given fingerprint, probability distribution of each feature over the whole image is estimated, and then a classifier adaptive to the fingerprint is constructed by considering the discriminability of each feature for two-class (background and foreground) classification problem. The fingerprint image is segmented by classifying each image block via the classifier. Mathematical morphology and region boundary smoothingis applied as post processing to obtain compact clusters and to reduce the classification error. The performance of new algorithmis evaluated on FVC2004 database, and the experimental results show that new algorithmcan segment the fingerprints effectively, and also improve the accuracy of matching substantially.

An Improved CMOS PLL with Dual Control Paths

SONG Ying,WANG Yuan,JIA Song,LIU Zhi,ZHAO Baoying

2009, 45(4):  585-588. 

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The authors propose an improved phased locked loop(PLL) architecture with dual control paths. The two control paths have different voltage controlled oscillat or (VCO) gain. The coarse tuning path has a large VCO gain, and is used to cover operating frequency range. Having a small VCO gain, the fine tuning path determines the loop bandwidth and optimizes the jitter performance. This circuit is fabricated in a 0. 18 μm CMOS logic process. The presented PLL has an output range from 600MHz to 1.6 GHz, and exhibits good jitter characteristic.

Novel Encoding Schemefor Folding and Interpolating ADC

LIU Zhen,JIA Song,WANG Yuan,JI Lijiu,ZHANG Xing

2009, 45(4):  594-598. 

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A novel encoding scheme with high speed and low power is proposed for folding and interpolating ADC. In the encoder,XOR-OR encoding algorithmand a novel serial-parallel Domino circuit are adopted. A novel method for wide-range error correction and bit synchronization is presented. Simulation results show that the proposed encoder has about 56% decrease on power delay product compared to conventional ROMencoder and this encoder is more applicable for the folding and interpolating ADC with higher resolution.

The Bionic Orientation Mechanism in the Skylight Polarization Pattern

YAN Lei,GUAN Guixia,CHEN Jiabin,WU Taixia,SHAO Xuan

2009, 45(4):  616-620. 

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An orienting method is proposed for bionic navigation with the polarized light patterns. Combining theoretical analysis with experiment, authors build a kind of theoretic and experimental models. Then the sun’s relative position and a navigation reference line (solar meridian) are derived details for navigation system to provide orientation information. Finally, based on the horizon coordinate system, an example is given for the whole calculate process of direction angle.

Study of Ultra-Low Frequency Electromagnetic Wave Explorationto Deep Geological Information

ZHANG Zexun,HOU Guiting,QIN Qi ming,LI Peijun

2009, 45(4):  628-632. 

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The source of passive ultra-lowfrequency(ULF), the elimination of noise, and the interaction of ULF with underground substances are discused andtested. The zero magnetic field experiment shows that the ULFreceived by instrument comes from the emission of underground object. Because of the complexity of the source and exploration situation, it’s necessary for the received original ULF data to be filtered in order to get the clearer exploration curves which are less jammed. The exploration result of Tacan No.1 Well in Tarim Basin shows that the passive ULF technique can gain the deep geological information rapidly and accurately.

Application of Three-Dimension Geological Modeling and Visualization Systemin Anqing Copper Mineral Exploration

CONG Weiqing,PAN Mao,LV Caiyu ,WANG Jianqing,LI Changqing

2009, 45(4):  633-638. 

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The overall structure and principal functions of three-dimension geological modeling and visualization system were discussed. It was used in Anqing copper mineral exploration. The system is mainly composed of three-dimension structure modeling , three-dimensional attribute modeling and three-dimensional geological visualization. Based on the modeling functions and the actual data of Anqing copper mineral exploration, three-dimensional geological models were built. Through the visual analysis, good prospects for exploration were revealed by the extension trend to east southerly direction of copper iron ore. It shows that the three-dimensional geological modeling and visualization system will be very helpful for enhancing the efficiency and accuracy of mineral prospecting to build.

Comparison of Three Statistical Methods on Landslide Susceptibility Analysis: A Case Study of Shenzhen City

SI Kangping ,TIAN Yuan ,WANG Daming ,WULun ,ZHU Yalin

2009, 45(4):  639-646. 

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Three statistical methods, the Logistic regression, generalized additive models (GAM), classification and regression tree (CART), were applied to the analysis of landslide susceptibility in Shenzhen using. By calculating the Kappa value and the area under the ROC curve (AUC) through 10-fold cross validation, the authors made comparison of the three methods and evaluated the credibility of the landslide susceptibility maps derived. It can be concluded that under the condition of the study area, GAMis the best method while the performances of the Logistic regression and CART are approxi mately same. The Logistic regression and CART can be used to automatically detect the important factors, but by GAMthe relationship between every influencing factor and the dependent variable can be visualized.

Terrain Reconstruction from Contours by Skeleton Extraction Using Delaunay Triangulation and Voronoi Diagram

XU Limin,XUE An

2009, 45(4):  647-652. 

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A terrain reconstruction method was described. It used the relationship between the Delaunay triangle and its dual Voronoi polygon to extract the contour skeleton effectively in only one step. Then according to the relationship between the skeleton point and the geomorphological feature , the elevation of every skeleton point was interpolated. Finally, a new TIN was established from the skeleton and the original contourj ointly. The experiment showthat the method proposed could well amend the untrue flat region in TIN, making TIN describethe topographical features more accurately.

Research on Real Estate Development Simulation Based on GIS and ABM

SHEN Tiyan ,ZHANG Hongxia ,LI Xun ,LI Xi

2009, 45(4):  653-662. 

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The authors proposed a comprehensive simulation framework for real estate development by abstracting and modeling the self-learning behavior and interactions of the developers. Guided by the theory of ABM (Agent Based Model) and down-top routine, this framework was supported by data obtaining capacity of Remote Sensing and spatial analysis of GIS. The location choice model of developers employed multivariable regression model to achieve maximumutility, therefore developers bid for one land patch based on some competition mechanism. At last, experiments were taken in Beijing, and the authors analyzed the macro-spatial feature formed by micro behaviors of many local developers .

Long-Term Impacts of Urbanization on Surface Runoff in the Xitiaoxi River Watershed, Eastern China

LI Na ,XU Youpeng ,GUO Huaicheng

2009, 45(4):  668-676. 

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The GIS-based long-term hydrological impact analysis (L-THIA GIS) model was used to simulatethe long-term impacts of urbanization on surface runoff in the Xitiaoxi River watershed in the upper reaches of Taihu Lake. Two historic land use scenarios (1985 and 2000) were analyzed to track land use changes in the watershed andto assessthe impacts of land use changes on annual average runoff. There was a 75% increase in urban land area from 1985 to 2000; consequently, the runoff coefficient increased by 1.4%. When the total urban area occupied was assumed to be 25% or 45% of the entire watershed, the runoff coefficient reached 0.68 or 0.79, respectively. Therefore, a reasonable urban land use plan is needed to limit blind urban expansion; the curve number should be used as an index in land use planning.

Bypass Demonstration Work of the Step-Feeding Biological Contact Oxidation Process for River Water Purification

ZHANG Hui ,WEN Donghui ,LI Lu ,XIE Shuguang

2009, 45(4):  677-684. 

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The Daqing River is the most seriously polluted river in the Dianchi Lake watershed. A bypass demonstration work of step-feeding biological contact oxidation process ( SBCOP), with the treatment scale of 1000 m³day and the hydraulic retention time (HRT) of 4.75 hours, was built aroundthe river bank to purify the river water. During the winter dry seasonfrom Nov. 2007 to Mar. 2008, three sets of parameters of the demonstration work were operated by regulating step-feeding ratio and air-water rate according to the influent qualities and climatic conditions. The results show that the SBCOP demonstration work kept good removal efficiencies for COD and NH⁺₄ - N, and the averager emoval rates were 37.3% and 32.9% each. The step-feeding ratio of 1∶1∶1 was beneficial for removing COD and NH⁺₄ - N. The removal rate of NH⁺₄ - N decreased when the concentration of NH⁺₄ - N increased. The average removal rate of TN was as lowas 10.5%, owing to the negative impacts of low temperature, carbon source shortage, high DO level of the influent, and loose and porous bio film. Theremoval of TP depended on the deposition of sludge and adsorption of Spirogyra sp., and the average removal rate of TP was 13.7%. To avoid the minus removal rate of TP, sludge discharge and removing of dead Spirogyra sp. were needed. The air-water rate of 2 ∶1 was suitable when influent was Dianchi Lake water.

Simulation on the Energy Balance over Moving Dune and Farmland in Keerqin Desert Area

CHEN Jinmin ,PENG Yan ,ZHU Hao ,ZHANG Hongsheng

2009, 45(4):  685-692. 

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Based on the applicability of one-andtwo-layer resistance models, the heat and water vapor transfer over moving dune and farmland in Keerqin desert area is simulated. The calculated fluxes are compared with values measured using Bowen ratio energy balance methods . It is found that the calculated fluxes are in agreement with the measurements. The sensible heat flux, latent heat flux, and the net radiation over moving dune are smaller than those over farmland. This result is attributed to the difference of albedo and hydrothermal characteristics between the two different underlying surfaces. The peak value of latent heat flux appears earlier than that of the sensible heat flux over the moving dune.

Analysis on an Unusual Snowstorm Event Caused by Explosive Cyclone

CAI Lina ,SUI Yingjiu ,LIU Daqing ,WANG Shuang ,LIU Wei ,WANG Tiankui

2009, 45(4):  693-700. 

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A snowstorm event caused by explosive cyclone happened in Liaoning Province in March 3-5, 2007. The cyclone caused heavy snow, strong winds and low visibility, which had large influences onthetraffic, particularly on aviation. The authors analyze the process fromthe large-scale circulation, mobile path and intensity of the cyclone, moisture conditions, cold and warm air, etc. The results show that strong baroclinic wave is the main reason for the development of the explosive cyclone, and that high potential vorticity in the stratosphere promote the development, too. High-and low-level jets, divergence field, vertical movement constitute a strong secondary circulation. The snowstorm in Shenyang is closely related to the movement of cyclones path, water vapor transport and the degree of vertical movement.

Contributions of Washout Process of Particles to Ion Concentrations in Rainwater

XIE Peng ,HUO Mingqun ,SUN Qian ,LIU Zhaorong ,BAI Yuhua ,LI Jinlong

2009, 45(4):  707-712. 

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The authors collected and analyzed three rainwater samples in Shenzhen in April and four rainwater samples in a rural area of Taian in July, 2007. The ion species in PM_2.5 and PM₁₀ concentrations were measured to get the influence of washout process of particles on ion concentrations in rainwater. Compared to that in Taian, the rainwater in Shenzhen showed higher ion concentrations and stronger acidity. The washout process made a more important contribution to ion concentrations in rainwater in Taian than in Shenzhen, because Taian had a more serious air pollution. The washout process of particles was very important. The scavenging ratios of Ca²⁺ and Mg²⁺ in PM²⁺ were high for Ca²⁺, Mg²⁺ mostly existed in coarse particles. NO^-₃, NH⁺₄, Cl^- and K⁺ mainly existed in fine particles and had smaller scavenging ratios. SO₂ and H₂SO₄ contributed a lot to the concentration of SO^2-₄ in rainwater and therefore SO^2-₄ had a high scavenging ratio.

Study of Urbanization Impact on Air Temperatures in Chengde

MA Fenglian ,HUANG Jiayou ,LI Qingxiang ,AI Liming

2009, 45(4):  701-706. 

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Trends of air temperatures and urbanization impact were studied using mean air temperatures and soil temperatures at the depth of 40 cm from Chengde observation station during 1964-2007. The results show that air temperatures have rosen remarkably in Chengde over the last 44 years. Linear trend analysis shows that annual air temperatures rose by about 0.269℃ per 10 years, and 0.099℃ came from urbanization impact. Since 1980, the warmingtrend was about 0.421℃ per 10 years because of urbanization impact. Air temperature rose more in winter and spring than in summer and autumn, and the urbanization impact to the air temperature was the most important factor.

Assessment of Ecological Risk to Climate Change of the Farming-Pastoral Zigzag Zonein Northern China

SUN Xiaoming ,ZHAO Xinyi

2009, 45(4):  713-720. 

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Climate risk index and ecological risk index over the past 47 years (1961-2007) in the medial area of the farming-pastoral zigzag zone in Northern China were constructed and analyzed to find its local response to global climate change. The results show that: 1) during 1961 to 2007, the integrative trend of climate risk index was increasing, which meant an increasing climate risk. The index increased from the southeast to the northwest. Abagaqi, which located in Inner Mongolia Autonomous, showed an extremely high climaterisk. Hunshandake sandy land and Korqin sandy land andtheir surrounding areas also faced high risk, most probably got worse. 2) The spatial distribution of ecological risk index was in agreement of latitude inthis local scale, which marked a increasing risk at higher northern latitude. Ecological risk index also changed depending on longitude. It turned out that the risk got extremely worse in the west. High risk and extremely high risk areas centrally distributed in Hunshandake sandy land partly in the Southern Abagaqi and Korqin sandy land partly in the eastern Wengniuteqi. 3) The contrast between actual risk distribution and condition changed risk distribution obviously suggested that actually high risk areas were more sensitive to the change of grassland coverage density and climate change.

Characteristics of Urban Ecological Water Requirement in Bao’an, Shenzhen

MAO Xiaoling,TIAN Kun,LI Tianhong,XU Yi

2009, 45(4):  721-727. 

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Based on the case study of Bao’an, Shenzhen, this paper analyzes the characteristics of Urban Ecological Water Requirements( UEWR) during 1988-2004. The relationships among UEWR, water resources and land use are studied. The results are summarized as below: the amount of UEWR of Bao’an decreased remarkably from 2.12×10⁸m³ in 1988 to 1.60×10⁸m³ in 2004. The components of UEWR including forest, grassland and water ecosystems show the different trends. The significant positive correlation between UEWR and land use is found in this study. The ratio of UEWR in water resources structure is about 24%-33%. Water resources allocated to human society should be limited by 60%-70% in order to maintain the healthy ecosystemand urban sustainable development.

Study on Network Analysis for Urban Ecological Security Patternin Changzhou City

CHANG Hsiao-Fei,LI Zhengguo,WANG Rusong,WANG Yanglin,LI Feng,Xiong Xiaxian

2009, 45(4):  728-736. 

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To improve and optimize pattern and functions of urban ecosystem, this study tried to indicate urban ecological security pattern conceptually based on correlative studies and chose Changzhou city for a case study. Urban ecological security pattern bythe least-cost distance model was established to integrate natural environment factors and landscape pattern characteristics. Because urban area was composed of social, economic and natural systems, this study divided urban landscape into four color classes according to the various landscape pattern and functions. Hereinto, red landscape was building area that supported living, production, and other social economic activities, gray landscape included different traffic lines and communication corridors could maintain diffusion and transfer of energy, money, products andinformation. Greenlandscape was composed of forest, cropland, and grassland and blue landscape contained river and lake both could preserve biodiversity and adjust environment. Through tracing the landscape function flows, positioning the interaction points of landscape functions, and identifying the frangible area with unsuitable land use, spatial extent with potential ecological risk could be deter mined. Finally, for urban growth and sustainable development, this study put forward urban ecological security pattern to relieve and save ecological risks by setting areas and rules of different land use zones such as prohibited zone, limited area, regulated area, optimized area and potential development area.