• Issue 3,2013 Table of Contents
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    • >土木工程与建筑学
    • Aerodynamic Measures for Mitigation of Across-wind Responses of Super Tall Buildings:State of the Art

      2013, 41(3):317-323. DOI: 10.3969/j.issn.0253-374x.2013.03.001

      Abstract (1153) HTML (16) PDF 1.10 M (1116) Comment (0) Favorites

      Abstract:With the development of science and technology, modern super-tall building is becoming more slender and flexible, which will lead to more serious across-wind loads and responses of them. Measures for mitigation of across-wind loads and responses of super tall buildings are mainly aerodynamic measures, structural measures and additional dampers. Appropriate designing of architectural configuration or appropriate local modifications of cross-section of buildings can mitigate the across-wind loads and responses, which is the mechanism of aerodynamic measures. This paper presents an overview of past/recent work on aerodynamic measures for mitigation of across-wind responses of super tall buildings, including selecting basic cross-section configuration with good aerodynamic features, modifying corner details, variation of cross-section shape along building height, openings on building walls, and so on. Furthermore, issues of concern in the research and application are pointed out, and suggestions for future research are also given.

    • Dynamic Extending of Elastic Plastic Damage Model for Concrete

      2013, 41(3):324-329. DOI: 10.3969/j.issn.0253-374x.2013.03.002

      Abstract (1475) HTML (40) PDF 834.77 K (1461) Comment (0) Favorites

      Abstract:Concrete exhibits strain-rate sensitivity during dynamic tests. In this paper, the practical elastic plastic damage model for concrete under static loading previously proposed by the authors is extended to account for the concrete strain-rate through the viscous regularization of damage variables. Stiffness damp stress is introduced into the model to consider the energy dissipation at the material scale. Tension plastic strain is introduced to the model to relax the descending and damage development. The proposed model is developed in ABAQUS, the nonlinear analysis of Koyna concrete dam indicates that the stiffness damp can observably enhance the stability of nonlinear dynamic implicit analysis. The introduction of tension plastic strain can also improve the calculation effect, and strain-rate sensitivity can affect the displacement reflect of the structure as well as improve the numerical stability.

    • On Seismic behavior and damage assessment of recycled aggregate concrete filled steel tube column

      2013, 41(3):330-335. DOI: 10.3969/j.issn.0253-374x.2013.03.003

      Abstract (1530) HTML (51) PDF 834.42 K (1181) Comment (0) Favorites

      Abstract:This paper presents a low frequency cyclic loading test for six recycled concrete filled steel tube (RCFS) columns. The main parameters in this study include the recycled coarse aggregate (RCA) replacement percentage and the strength of core concrete. The bearing capacity, stiffness degradation, ductility, energy dissipation capacity and failure pattern of columns with different RCA replacement percentage are experimentally studied. Research findings indicate that the RCFS columns exhibit fine seismic behavior. The energy dissipation ability, ductility and hysteresis performance change slightly with the variation of the RCA replacement percentage and concrete strength. It is also figured out that the bond-slip has little effect on the seismic behavior of the RCFS columns, and the RCA replacement percentage does not influence the bearing capacity of confined recycled concrete columns obviously. Finally, an improved damage assessment model which is based on the Miner principle is developed. The damage level of RCFS columns is better reflected by this model, and the analysis results are in accordance with the test ones.

    • A Numerical-Analytical Mixed Method of Hydrodynamic Effect for Deep-Water Elevated Pile Cap Foundation under Earthquake

      2013, 41(3):336-341. DOI: 10.3969/j.issn.0253-374x.2013.03.004

      Abstract (1321) HTML (43) PDF 858.00 K (1691) Comment (0) Favorites

      Abstract:This paper focused on the dynamic analyses of the deep-water elevated pile foundation in contact with water. A simplified analysis model of the pile foundation considering the hydrodynamic effect is proposed firstly. The numerical-analytical mixed method for earthquake induced hydrodynamic added mass is provided as follows: for piles, an analytical solution based on the scale of the underwater pile is given including the effect of pile group; for cap, a simple finite element method based on the potential-based fluid formulation is developed considering the geometry and vibration periods of the cap. The proposed mixed method is applied to a 4-pile experimental specimen for the modal and time history analyses. The results are shown good satisfactory when compared to the experimental data, or to the finite element solutions and other analytical solution in the literature. The method improves the calculation accuracy and efficiency and is a valuable reference for the seismic analysis and design of the deep-water elevated pile cap foundation.

    • Seismic Behavior Analysis for Link Beam of Double-Column Bent

      2013, 41(3):342-347. DOI: 10.3969/j.issn.0253-374x.2013.03.005

      Abstract (1345) HTML (50) PDF 866.59 K (971) Comment (0) Favorites

      Abstract:To explore what seismic behavior effects link beam will have on its double-column bent based on pushover analysis method. The elastic-plastic fiber surface element is applied to the construction of three respective models — single-column bent model, double-column bent model and link beam double-column bent model, to study the difference of failure mechanism of piers ,displacement ductility capacity on the top pier, displacement ductility factor and force acting on the foundation by changing the stiffness of link beam. The results of these analyses indicate that with the increasing stiffness of link beam, there will be a decreasing trend of displacement ductility capacity on the top pier, a gradual increase of displacement ductility factor and load-carrying capacity of piers, thus more lateral force capacity will be passed to the foundations. For the regular pier, the maximum plastic displacement on the top pier of the link beam of double-column is slightly smaller than that of single column bent .and its displacement ductility capacity can be calculated as that of single column bent.

    • Stochastic Fragility Analysis of Bridges Considering the Material Deterioration

      2013, 41(3):348-354. DOI: 10.3969/j.issn.0253-374x.2013.03.006

      Abstract (1455) HTML (19) PDF 984.78 K (1332) Comment (0) Favorites

      Abstract:Nowadays, structural capacities of many bridges in China degrade due to material deterioration and other reasons. It increases the possibility of fracture or even collapse of these bridges under action of earthquake. Therefore, this project focuses on developing a seismic fragility method and proposes a fragility assessment procedure for typical highway bridge systems considering structural material deterioration. In this study, a material deterioration model is developed. And a structural capacity and demand model considering material deterioration using ANN-MC method is developed. Based on the capacity and demand model, fragility curves are formed. Moverever, a case study of the main tower of cable-stayed bridge using the proposed method is provided to illustrate the details and structural vulnerlability. These achievements will provide theoretical basis and analysis support for the life-cycle design, the operation and management, especially the seismic hazard assessment of the existing bridges.

    • Automatic Cable Force Adjustment For Cable Stayed Bridge Based On The Influence Matrix And Particle Swarm Optimization Algorithm

      2013, 41(3):355-360. DOI: 10.3969/j.issn.0253-374x.2013.03.007

      Abstract (1431) HTML (16) PDF 911.91 K (900) Comment (0) Favorites

      Abstract:As a high level statically indeterminate structure, the cable forces of cable-stayed bridge are often need to be computed tautologically both when doing FEM structural analysis or construction observation computing of bridge. This time consuming computing process also need well training on analytical mechanics and deep insight to the behavior of bridge structure. In this work, an influence matrix and particle swarm intelligence optimization algorithm based cable force adjustment computing Algorithm are proposed, with the aims to realize the automatic cable force adjustment when facing the cable stayed bridge structural analysis or construction observation computing tasks. The cable force adjustment is modeled as an auto resolution space searching process with the optimization objective expressed by influence matrix of bridge, and particle swarm intelligence optimization algorithm replaces the tautological manual tentative calculation. The programs are developed and applied to the true cable stayed bridge, and the result showed that in most cases, a rational resolution for cable force collection can be arrived at handily and promptly, without any manual interventions. And in all case, the relative errors are under controlled less than 2%. The proposal method is expected to provide a efficient resolution or guideline for structural FEM analysis and construction observation computing on cable stayed bridge.

    • Analytical on distribution law of soil settlement caused by unsteady dewatering confined water

      2013, 41(3):361-367. DOI: 10.3969/j.issn.0253-374x.2013.03.008

      Abstract (1317) HTML (35) PDF 894.01 K (1105) Comment (0) Favorites

      Abstract:Decompression and dewatering in confined aquifer is essentially an unloading process, and calculating overlaying soil settlement of confined aquifer can be used to derive formulas based on the elastic half-space of Mindlin displacement solution. Analysis shows that influence of dewatering time of unsteady seepage in infinite confined aquifer on soil settlement is significant compared to the steady seepage. Soil settlement caused by decompression and dewatering of confined water increases with increase of distance from ground and the maximum value emerge on the roof of confined aquifer. In seven parameters affecting ground settlement, influence of Possion’s ration and confined aquifer’s permeability coefficient on ground settlement is very little. Ground settlement will decrease gradually with increase of overlaying soil’s thickness and confined aquifer’s thickness, The influence of elastic modulus on ground settlement is great when its value is small but influence of that gradually weakened with increase of elastic modulus. Ground settlement increase with increase of out-water volume of single well and water head drawdown, furthermore, the relation ship between them nearly to linear relationship, then, out-water volume of single well, confined aquifer’s thickness, water head drawdown and elastic modulus of overlaying soil not only affect value of ground settlement, but also affect the spatial distribution of ground settlement.

    • Experimental study on fatigue behavior of steel reinforced concrete girders in high speed railway station

      2013, 41(3):368-373. DOI: 10.3969/j.issn.0253-374x.2013.03.009

      Abstract (1255) HTML (23) PDF 915.01 K (1036) Comment (0) Favorites

      Abstract:For the needs of application of steel reinforced concrete (SRC) girders in high speed railway stations, both static and 2 million-cycle fatigue tests on three H-section steel reinforced concrete girders with the same dimension and constructional detail as that of a real engineering project were carried out under design loading. After that, further fatigue tests continued with higher loading than the design loading. The specimens, applied loading and testing program as well as experimental results are presented. The structural behavior under static and fatigue loading is compared. The failure feature of SRC girders about fatigue crack initiation and propagation is described. The current investigation indicated that the SRC girders kept in good condition and at the stage of elasticity when they were subjected to design static loading and 2 million-cycle fatigue loading. The concrete surface crack developed did not exceed 0.2 mm. Fatigue failure occurred after these girders were applied higher-level loading and endured from 0.31 to 1.46 million cycles. Before the fatigue failure, all components in the SRC girders were able to collaborate well and their strain distribution was in agreement with an assumption of plane cross section. The fatigue failure initiated from welded connection between a flange and a web in H-section steel. The fatigue behavior of the welded H-section steel beam played a key role in the fatigue strength of SRC girders. The suggestions for improving the fatigue strength of the SRC girders and future research work are recommended finally.

    • A Numerical Algorithm for Solving Two-dimensional Arbitrary Distribution of Multiple Cracks

      2013, 41(3):374-380. DOI: 10.3969/j.issn.0253-374x.2013.03.010

      Abstract (1191) HTML (24) PDF 911.09 K (1085) Comment (0) Favorites

      Abstract:Based on the basic idea solving multi-domain combinations with virtual boundary element least square method, that each crack can be treated as a pair of sub-domains, and learning from the interpolation of the compactly supported radial basis function used in boundary-type meshless methods to approximately construct the virtual source function on the virtual boundary corresponding to each sub-domain, the computational scheme with the virtual boundary meshless least squares analyzing two-dimensional multi-crack problems is established. According to the definition about sub-domain in this paper, the added extra sub-domains on the boundary extended along the crack surface as “conventional sub-domain method” in the direct boundary element method do not have to be considered, thereby reducing the computational, especially avoiding this calculation error caused due to inadequate number of the elements or with the collocation points configured on the boundary of the additional sub-domains and its improper configuration. In order to verify feasibility and accuracy of the numerical algorithm proposed in the article and discuss the interaction between multiple cracks with arbitrary distribution, some examples, such as a single center crack, third-adjacent spacing of different length collinear cracks and one horizontal crack and one different inclined angle crack by one-way tension in infinite plate, are given. The results show that this method leads to higher accuracy in comparison with the other methods considered in this study.

    • A Review on Risk Matrix Method and Its Engineering Application

      2013, 41(3):381-385. DOI: 10.3969/j.issn.0253-374x.2013.03.011

      Abstract (1885) HTML (55) PDF 798.32 K (1128) Comment (0) Favorites

      Abstract:Risk Matrix Method (RMM) is widely used in engineering field since it is succinct and practical to perform, while the validity of its assessment results has also been challenged since its appearance. By illustrating the connotation of risk in Risk Matrix Method and the similarity between Risk Matrix and Covariance Matrix, a general retrospection on the origin of RMM is performed. The basic mathematical model of Risk Matrix is introduced by adopting classification function, elucidating some theoretical issues of RMM. According to the accuracy issues of risk assessment, the notion of uncertainty is proposed as an evaluation index. The meaning of RMM uncertainty in engineering application is clarified. Based on the mathematical model, appearance of RMM uncertainty, sourcing from Risk Matrix establishment process, risk ties and the matrix evaluation form, are discussed. In the end, a general review on how to recognize and control the corresponding uncertainties properly and effectively is delivered and the future development directions are provided.

    • >交通运输工程
    • Improved Calculation Method of Permanent Deformation for Cohesive Subgrade Soil

      2013, 41(3):386-389. DOI: 10.3969/j.issn.0253-374x.2013.03.012

      Abstract (1300) HTML (46) PDF 570.13 K (1078) Comment (0) Favorites

      Abstract:The paper presents a study on permanent deformation characteristics of clayed subgrade soils on the basis of the repeated load triaxial test, the relationship between permanent strain and loading times was tested through 36 working conditions, a prediction model for permanent deformation of cohesive subgrade soils is established by improving and calibrating NCHRP-37A model. Based on the layerwise summation method, and combined with the consideration of highly channelizing road traffic, put forward the itemize and layerwise summation method as improved method to calculate permanent deformation of cohesive subgrade soil under vehicle repeated load, calculation principle and steps of this improve method was explained in detail. Combined with a case study of typical asphalt pavement structure, permanent deformation of clayed subgrade soils is calculated, and through the contrast analysis, the rationality of this method was verified.

    • Variability Analysis of Civil Airfield Concrete Pavement Structure Strength

      2013, 41(3):390-396. DOI: 10.3969/j.issn.0253-374x.2013.03.013

      Abstract (1119) HTML (21) PDF 885.12 K (580) Comment (0) Favorites

      Abstract:Based on the in-situ data of 427 pavement cores including 35 civil airports, the structural strength variability was analyzed and the variability distribution pattern was provided. The results of ANOVA analysis indicate that pavement service time, airfield grades, various locations, and respective airports mostly accepts the test of significance, so the pavement structural design based on reliability is more reasonable. In the end, the reliability coefficient in pavement design is proposed based on the structural strength variability accumulative frequency distribution.

    • Research on permanent deformation of steel deck pavements with different combinations

      2013, 41(3):397-401. DOI: 10.3969/j.issn.0253-374x.2013.03.014

      Abstract (1280) HTML (70) PDF 693.54 K (1789) Comment (0) Favorites

      Abstract:For five types of pavement structures combined with gussasphalt and epoxy asphalt concrete, the repeated shear tests with constant height were conducted to obtain the rheological characteristics of the two pavement materials firstly. And then, the creep parameters of pavement materials were fitted with multiple nonlinear regression based on Bailey-Norton model. With the parameters of materials, the finite element model of orthotropic steel deck pavement were established to simulate the permanent deformation of pavement at 60 degrees Celsius. Finally, the simulation results were verified through modified wheel track test. Research results show that in the two-layers pavement structures combined with different asphalt concrete, gussasphalt concrete has the most of deformation contribute rate, while epoxy asphalt concrete has the less of deformation contribute rate. However, in the two-layers pavement structures combined with same asphalt concrete, the rutting damage happened at surface course. The research findings provides technologies foundation for high-temperature performance design of structures and materials of steel deck pavement.

    • A design guide to shear resistance of bonding layer in concrete bridge deck asphalt pavement

      2013, 41(3):402-407. DOI: 10.3969/j.issn.0253-374x.2013.03.015

      Abstract (1368) HTML (42) PDF 743.44 K (902) Comment (0) Favorites

      Abstract:A new approach to evaluate shear resistance of bonding layer in concrete bridge deck asphalt pavement was proposed. The distributions for shear stress and normal stress in the interface between asphalt pavement and bridge slab under vertical and horizontal load by finite element method. Based on the scattergram of shear stress and normal stress, the conception of shear stress critical boundary was proposed. Parameters of pavement and load were considered to analyze its effects on critical boundary. Also, equation formation of critical boundary was tested by χ2-test. The basic condition which would guarantee the performance of shear resistance for bonding layer is that there is no intersection of shear stress critical boundary and shear intensity envelope line, which is the design standard for bonding layer in concrete bridge deck asphalt pavement. Finally, a case study was presented.

    • Isolated Transit Signal Priority Control Strategy Based on Demand Degree of Green

      2013, 41(3):408-414. DOI: 10.3969/j.issn.0253-374x.2013.03.016

      Abstract (1122) HTML (27) PDF 1.01 M (815) Comment (0) Favorites

      Abstract:The traditional transit signal priority control strategy cannot effectively deal with multiple priority requests from different direction. The concept of demand degree of green is proposed, calculation of demand degree of green on green phase and red phase is designed, decision-making flow of phase change based on demand degree of green is proposed. Take full account of the arrival, queue and waiting of transit vehicles and general vehicles, and demand degree of green that consider transit priority is calculated. On this basis, transit signal priority control based on demand degree of green is realized by the phase change decision-making. Simulation test and result analysis show that the proposed control strategy is more efficient than traditional transit priority control strategy. Comparison to skipped phase sequence, the priority effect of control strategy based on fixed phase sequence is slightly worse, however, the negative impact of general vehicles is less. When the traffic volume is increased, the increase of average delay of transit vehicles is small; however, the increase of average delay of general vehicles is quite large.

    • Investigation of Platoon's Driving Characteristics & Traffic Impact

      2013, 41(3):415-421. DOI: 10.3969/j.issn.0253-374x.2013.03.017

      Abstract (1469) HTML (40) PDF 1.00 M (969) Comment (0) Favorites

      Abstract:To ensure the security of the platoons used in urban mega-event and to prevent platoons from driving disorder, the evaluation indicators were selected, including average vehicle delay, minimum departure interval and chasing distance. On the basis of traffic flow wave theory, the indicators were used to analyze the impact of driving condition that was resulted from the changing of platoons’ length, departure interval and speed when going through the bottleneck. The social vehicles’ delay caused by the platoons when passing through the intersection was also discussed. At last, the opening ceremony of Shenzhen Universiade was taken as an example. The result shows the increasing length and speed difference that between bottleneck and normal section has a negative impact on driving stability. It is also found that intersection delay decreasing when the platoon’s length and departure interval increase.

    • >环境科学与工程
    • Impact of anaerobic reaction time on denitrifying phosphorus removal performance and microbial structure dynamics

      2013, 41(3):422-427. DOI: 10.3969/j.issn.0253-374x.2013.03.018

      Abstract (1504) HTML (32) PDF 881.56 K (868) Comment (0) Favorites

      Abstract:For denitrifying phosphorus removal systems, whether the anaerobic metabolism conducted successfully directly determines the denitrification and P uptake performance in the subsequent anoxic phase. Therefore, anaerobic reaction time (AnRT) has become a key parameter when designing denitrifying phosphorus removal process. The long-term impact of the different anaerobic reaction times (i.e. 90, 120 and 150 min) on denitrifying phosphorus removal performance was conducted in an anaerobic/anoxic/aerobic (An/A/O) sequencing batch reactor (SBR). Also, the microbial structure dynamics were analyzed by fluorescence in situ hybridization (FISH) techniques. The results showed that the system with the shortest anaerobic time of 90 min produced the highest amount of PHA during anaerobic phases, and the average nitrogen and phosphorus removal efficiencies maintained at 92% and 93%, respectively; also, the corresponding phosphorus accumulating organisms (PAOs) was accounted for 58±2.3% of the total biomass. The average nitrogen and phosphorus removal efficiencies of the system with the anaerobic time of 120 min maintained at 97% and 73%, respectively; and the corresponding PAOs was accounted for 50±2.3% of the total biomass. The lowest anaerobically synthesized PHA was occurred in the system with the anaerobic reaction time of 150 min, accompanied by the poorest N removal efficiency of 79% (mean value); also, the PAOs percentage was reduced to 45±2.7%. It appears that a too long anaerobic reaction time had led to a decreased level of the PHA content and increased free nitrous acid (FNA) accumulation, which ultimately resulted in the reduced nitrogen and phosphorus removal efficiencies.

    • Separation Performance and Influencing Factors of Grit Separation Module

      2013, 41(3):428-432. DOI: 10.3969/j.issn.0253-374x.2013.03.019

      Abstract (1176) HTML (38) PDF 696.78 K (1127) Comment (0) Favorites

      Abstract:In order to eliminate grit’s effection to the waste water treatment plant, a grit separation module was developed base on the differences between biological materials and inorganic grit in the sludge and cyclone separation characteristic. The pilot scale field studies were conducted at full-scale wastewater treatment plant in Chongqing. The results showed that the outlet ratio K of the separation module is the most important structural parameters. Improve the working pressure P, can increase separation performance and processing ability. The grit separation module with a cone angle 20 °, the overflow outlet diameter Ф22mm, bottom outlet diameter Ф13mm, the working pressure is 0.15 ~ 0.2MPa, is used for separation grit from the sludge, after separation, the overflow sludge volatile suspended solids(VSS)/ total suspended solids(TSS) is 3 times to the underflow and the underflow grit is 1.5 times to the overflow, 46% the original sludge grit was enriched in ,volume flow ratio 17%, the underflow, to achieve grit separation and enrichment.

    • Water Distribution Systems Layout Analysis Based on Link Importance Indicator

      2013, 41(3):433-436. DOI: 10.3969/j.issn.0253-374x.2013.03.020

      Abstract (1283) HTML (19) PDF 565.68 K (836) Comment (0) Favorites

      Abstract:The concept of link importance has been introduced to quantitatively measure the relative value of a link in the water distribution system model. With case study, different pipe configurations such as branched, looped, mixed and dual-source network were constructed. The link importance values calculated and a comparison is made between the configurations with hydraulic analysis. Some views contribute to the impact of water network layouts on link importance were concluded: Branched network has no redundant connectivity or capacity of water supply for the reason that there is only one flow route from source to a consumer. Looped network contains redundant flows paths necessary, however, the capacity of water supply depends on the overall configuration. Local effects with increasing number of primary loop. The pipe near the connected pipe is affected significantly, while the pipe far from connected pipe remains unaffected. The link importance of each pipe in loop descends as water supply pressure rises.

    • >机械、车辆与能源工程
    • Wheel Reprofiling of High-speed EMU Based on Multi-objective Optimization Strategy

      2013, 41(3):437-442. DOI: 10.3969/j.issn.0253-374x.2013.03.021

      Abstract (2833) HTML (71) PDF 863.99 K (1396) Comment (0) Favorites

      Abstract:A new approach was presented to optimize worn wheel reprofiling of the high-speed electric multiple unit(EMU), and three functions were selected as the objective functions, respectively related to the critical velocity of vehicle system dynamics, the contact stress affecting the contact fatigue of wheel-rail wear and the diameter of the nominal rolling circle of a wheel, with vertical coordinates of control points on the wheel profile curve as design variables and their upper and lower values as corresponding additional conditions, with the height, thickness and contact angle of the wheel flange as well as the derivative of the wheel profile curve as geometric constraint parameters. A model of multidisciplinary optimization was established for wheel reprofiling of high-speed EMU, afterwards, corresponding comparison analysis was performed. Results show that, based on the reprofiling model of multi-objective optimization, the comprehensive performance of a standard wheel profile can be closely obtained by not reprofiling the worn wheel to the standard profile, and the amount of wheel reprofiling is reduced and life-time of wheelset is extended.

    • Optimization Design of Geothermal Heat Exchangers in Diaphragm Walls

      2013, 41(3):443-448. DOI: 10.3969/j.issn.0253-374x.2013.03.022

      Abstract (1028) HTML (13) PDF 857.85 K (816) Comment (0) Favorites

      Abstract:To bury absorber tubes in diaphragm wall as heat exchanger is a new developing direction of ground source heat pump technology. However, the researches on the design method of heat exchangers embedded in diaphragm walls are so far relatively rare. According to the heat transfer models of heat exchangers in diaphragm walls and the flowing temperature field inside heat exchangers, a calculation method of variable heat exchange capacity of heat exchangers in diaphragm walls and temperature of outlet water was proposed. The regression equations of the heat exchange rate and the highest temperature of outlet water while cooling load of overground building reaches maximum were obtained based on orthogonal analysis. On these bases, an optimization design method of heat exchangers in diaphragm walls was presented, which may be used to get the optimum parameters of heat exchangers according to the limits of highest temperature of outlet water, length of a set of heat exchangers, as well as the width of a breadth of diaphragm wall. The optimization method was also applied to optimize the heat exchangers in diaphragm walls of Shanghai Museum of Natural History. The analyzed results indicate that the proposed optimization method is simple, and easy to use by designers.

    • >海洋与地球科学
    • Surface-related multiple suppression by independent component analysis

      2013, 41(3):449-457. DOI: 10.3969/j.issn.0253-374x.2013.03.023

      Abstract (1483) HTML (54) PDF 3.94 M (1222) Comment (0) Favorites

      Abstract:Multiples suppression by adaptive subtraction methods based on second order statistic can obtain a perfect result in case the primaries and multiples are orthogonal, but the assumption is always not valid. In this paper, we combine independent component analysis (ICA) with inverse scattering series (ISS) method to suppress surface-related multiples. Multiples predicted by ISS and raw seismic records make up several observation components, then multiples are separated from the seismic records by ICA. Tests on synthetic data generated by convolution and finite-difference modeling show the advantages of ICA in multiples suppression even mismatching in amplitude between the predicted multiples and raw seismic data. But there is uncertain in multiples separation by ICA in case of low signal-to-noise ratio.

    • Impact of Mega-Engineers in the Changjiang Drainage Basin on the Deposition and Erosion of Coastal Wetland, and Sustanability of Land Reclamation

      2013, 41(3):458-464. DOI: 10.3969/j.issn.0253-374x.2013.03.024

      Abstract (2021) HTML (33) PDF 1.02 M (1379) Comment (0) Favorites

      Abstract:Shanghai land area is about 7000 km2, of which 65 percentages has been built up by accumulation of Changjiang riverine sediment in last 6000 years, and 17.5 percentages is newly reclaimed land from coastal wetland. Land reclamation has greatly eased the tense relationship between socioeconomic development and available land resource in Shanghai, effectively slowing the reducing magnitude and speed of farmland area. To some extent, substanability of land reclamation directly influences Shanghai socioeconomic development speed and substanability. In the recent decades, Changjiang sediment discharge has dramatically decreased especially after the completion of Three-Gorges Dam, in terms of sediment discharge at Datong Station from 497 mt yr-1 in the period of 1951~1968 to 154 mt yr-1 in the period 2003~2008, and the latter is less than one third of the former. Decreasing trend of Changjiang sediment discharge will continue considering the impacts of South-to-North Water Diversion Project, under or planning construction large water reservoir in the upper drainage basin, and continuous inplement of Water and Soil Conservation program. Because of sharp decrease in Changjiang sediment charge, coastal wetland has been observed to slow aggradation and erosion has taken place in the increasing bigger area of the subaqueous delta. It is still questionable whether and when the Changjiang Delta will turn from net accretion into net erosion. Delft3d numerical model has been employed to simulate trend development of major mudbanks and river-mouth bars in the next 20 years with a reference year in 2005. The result shows that coast wetland above 5-m isobaths will continue its accretional trend whereas the rate will decrease. According to wetland distribution pattern and Shanghai long-term marine-resource planning outline, it is suggested that an area of 485 km2 and 770 km2 can be newly reclaimed or promoted sediment accretion by engineering. Furthermore, real-time and dynamic investigation and study should be carried out to increase our understanding of trend development of estuarine natural complex processes, especially under intensifying impacts of human activities. It is also pointed out that the long-term ecological value of coastal wetland has overtaken the exploitation value of land resource. In the future, coastal wetland should be evaluated in more objective and synthetical ways, typically including land usuage and biodiversity conservation, for development sustainability of both human and natural societies.

    • >经济与管理科学
    • Evaluation of firm bond with correlated third party guarantee

      2013, 41(3):465-469. DOI: 10.3969/j.issn.0253-374x.2013.03.025

      Abstract (1285) HTML (23) PDF 636.92 K (961) Comment (0) Favorites

      Abstract:This paper presents the pricing model for firm bond with the correlated third party guarantee in structural approach and takes into account the case that the guarantor may default because of the immediate future payment due to the default of secured party. Our model is a terminal boundary-value problem of PDE. And we numerically provide a discussion on the impact on the bond price by the parameters, such as firm asset, asset correlation, asset volatility, etc.

    • Dynamic Pricing Mechanism of Perishable Products based on markdown timing

      2013, 41(3):470-475. DOI: 10.3969/j.issn.0253 374x.2013.03.026

      Abstract (977) HTML (32) PDF 891.75 K (751) Comment (0) Favorites

      Abstract:Perishable product's optimal two-period dynamic pricing strategy and markdown timing were studied for the monopoly seller. We used Stackelberg game theory model and backward induction, then obtained how to maximum profit function facing strategy consumes when markdown timing was certain and uncertain. Finally, the optimal pricing strategy and markdown timing were computed by using MATLAB. The experimental results show that the first period price, markdown degree of the second period price and seller’s profit decrease, as the percentage of strategy consumer increases. The seller’s profit first goes up when the markdown point is postponed, then goes down. The delay of markdown point is advantageous for the seller as the percentage of strategy consumers increases.

    • Multi-dimension Reputation Model Design in Multi-agent System

      2013, 41(3):476. DOI: 10.3969/j.issn.0253-374x.2013.03.027

      Abstract (1122) HTML (14) PDF 995.11 K (704) Comment (0) Favorites

      Abstract:Reputation mechanism can be introduced to solve complex interaction problems and promote cooperation in Multi-agent System (MAS). Based on establishing two reputation representations, the reputation confidence level and the expected reputation level, we assume the aptitude assessment from a neutral party as another source of reputation information. Putting forward different similar operators in interactions and different weights of reputation information sources, we update the initiative reputation confidence levels from both the objective-rating dimension and the information-source dimension. Finally, we compute the ultimate reputation value by taking advantage of Dempster rule. We also apply the multi-dimension reputation model to online market to instance its effectiveness and practicability. Finally, we analyze the model’s efficiency and resistance for security threats, and conclude that multi-dimension reputation model can deal with the new agent’s reputation and incent the agents to give rate after interaction spontaneously and can also solve or alleviate 8 key security threats in distributed system.

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