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Table of Content

    25 November 2010, Volume 38 Issue 11
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    Materials Science & Technology
    Preparation and Characterization of Self-Setting Calcium Phosphate Microspheres
    Ye Jian-dong Li Jiang-bo Zhou Zi-qiang Yu Tao
    2010, 38(11):  1-6.  doi:10.3969/j.issn.1000-565X.2010.11.001
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    The novel self-setting calcium phosphate microspheres were prepared by the employment of a reversed emulsion method. The diameter of the microspheres distributed from 100 μm to 1000 μm with a median diameter between 388~605μm, with a porosity between 43.4%~66.7%. The processing parameters for preparation of the microspheres were optimized to be: an agitating speed of 200r/min, a gelatin concentration of 8%w/v, an oil to water ratio of 5:1, and a liquid to powder ratio of 2.0. The angle of repose of the microspheres was measured to be 28.4°~31.6°, indicating good flowability. The compressive test showed that the microspheres were non-brittle, which is in favor of clinical applications. The compressive performance of the microspheres was significantly improved after full hydration at 37°C and 97% humidity. Anti-disintegration test revealed the microspheres was endurable in simulated physiological conditions and MTT test indicated the microspheres were biocompatible. The self-setting calcium phosphate microspheres were a potential candidate for bone defect filling at non-load-bearing sites and drug carrier.

    Influence of Structural Characteristics of Air Bubbles on Salt Frost Resistance of Concrete
    Zhang Yun-qing Yu Hong-fa Wang Jia-chun
    2010, 38(11):  7-11.  doi:10.3969/j.issn.1000-565X.2010.11.002
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    The salt frost resistance,as well as the relationship between the salt frost resistance and the air bubble parameters,is investigated by means of the accelerated freeze-thaw method for common concrete,air-entrained concrete and high-performance concrete under the action of 3.5%（mass fraction） sodium chloride solution,respectively.The results show that the average spacing factor（） and bubble diameter（） of concrete is largely dependent on air content in a negative relation when the air-entraining agent is determined,that mineral admixture has no significant influence on the bubble characteristics of concrete and its regularity,that adding air-entraining agent is an effective means of improving the anti-freeze-thaw performance of concrete,and that there also exists a critical air content of concrete the same as common freeze-thaw performance,which is 2.0%～3.0% in common freeze-thaw environment and rises to 4.5%～5.0% in salt freezing environment.Moreover,it is found that the average spacing suitable for the salt frost resistance of high-performance concrete is related to the strength grade of concrete,and should be less than 250 μm when the strength grade of concrete is less than C50.Meanwhile,it can rise to 700 μm when the strength grade is greater than C60.

    Microstructures and Mechanical Properties of Welding Zone of 7022 Aluminium Alloy After Friction Stir Welding
    Wang Hong-feng Zuo Dun-wen Wang Min Li Guang Dong Chun-lin
    2010, 38(11):  12-16.  doi:10.3969/j.issn.1000-565X.2010.11.003
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    7022 aluminium alloy with a thickness of 10 mm was welded via the friction stir welding,and the influences of welding parameters on the microstructures and mechanical properties of the welded joint were investigated.The results show that,at a rotating speed of 400 r/min and a welding speed of 100 mm/min,the tensile strength and yield strength of the welded joint of 7022 aluminium alloy reach 615 MPa and 533 MPa,respectively,which are both greater than those of the base material,and that the microhardness of the welded joint is slightly lower than that of the base material.Moreover,it is found from the fracture surface analyses,it is found that the tensile fracture of the welded joint of 7022 aluminium alloy is ductile.

    A Novel Method for Measuring the Stress Distribution of Polymeric Melts in Flow Fields by Flow-Induced Birefringence
    Fan Ji-chang Peng Xiang-fang
    2010, 38(11):  17-20,46.  doi:10.3969/j.issn.1000-565X.2010.11.004
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    In order to calculate the stress distribution of the polymer melts in flow field,the conventional equipment of birefringence measurement is improved by reasonably rearrange the optical components in this paper,and a novel method to calculate the stress distribution of polymer melt in flow fields by measuring the flow-induced birefringence is proposed.The image obtained from this method contains both the information of the birefringence and the orientation angle,the orientation angle of the image is 45°where the light intensity gets maximum or minimum,so the shear stress alone the isoclinic line of an angle of 45°can be calculated,the deficiency of the conventional equipment that only used to measure the tensile stress along the axis of symmetry is overcome.In the last,the flow field of LDPE1810D in a self-made visualization die in extrusion condition was measured by using this equipment;the distribution of stress,along the isoclinic lines of an angle of 45°,was calculated.It is proved that this method is capable of the measurement of the birefringence of the flow fields,thus the stress distribution.

    Architecture & Civil Engineering
    Mechanical Performance of Laminated Concrete Pavement Materials Reinforced with Steel Fibers
    Wang Yi-min He Jun Jiao Chu-jie
    2010, 38(11):  21-25.  doi:10.3969/j.issn.1000-565X.2010.11.005
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    This paper deals with the mechanical properties of C40 concrete with a steel fiber dosage of 0～2.0%,and discusses the mechanical properties and economical efficiency of size-variable composite concrete with optimal volume ratio.The results show that the compressive strength of the steel fiber-reinforced concrete increases with the dosage of steel fibers,that the compressive strength increases by 27% and the flexural-tensile strength increases by 50% at the dosage of 1.5%,that the addition of steel fibers makes the load-displacement curve of the concrete change from elastic mode to elastic-plastic mode and improves the brittle fracture of the pavement,and that the two-layer composite concrete composed of steel fiber-reinforced concrete（with a steel fiber dosage of 1.5%） and common concrete in a thickness ratio of 1∶ 3 is of high strength,good anti-deformation ability and high economic benefit.

    A New Method to Calculate Axial Bearing Capacity of Composite Columns with Core of High-Strength Concrete-Filled Steel Tube
    Long Yue-ling Cai Jian
    2010, 38(11):  26-31.  doi:10.3969/j.issn.1000-565X.2010.11.006
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    Based on the analysis of the bearing mechanism of composite columns with core of high-strength concrete-filled steel tube,a new method to calculate the axial bearing capacity of the composite columns is proposed,which considers not only the difference in confinement effect between the concrete both inside and outside the tube,but also the influence of circular section and square section on the concrete outside the tube.The proposed method is then applied to the calculation of axial bearing capacity of 16 composite columns with core of high-strength concrete-filled steel tube,and the results are compared with those obtained by the existing methods.It is indicated that the calculated results accord well with the experimental ones,and that the proposed method is superior to the exis-ting methods because it can reasonably estimate the axial bearing capacity of composite columns with core of high-strength concrete-filled steel tube.

    Mechanical Properties of Broken Rock-Soil Mixture
    Cao Guang-xu Xu Ming Song Er-xiang
    2010, 38(11):  32-39.  doi:10.3969/j.issn.1000-565X.2010.11.007
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    With the help of a specially-designed large-scale oedometer,some experiments were carried out to investigate the compression,creep and wetting deformation of broken rock-soil mixture,which,with different broken rock contents,has been widely used in the airport construction in West China.The results show that the mixture is of high packing density,low compression and small initial creep rate when the broken rock content reaches 70%～80%,and that,for the same mixture at a certain pressure,the creep deformation is approximately linear to logarithmic time and the creep rate continuously increases with the stress level.Moreover,it is found that,when the mixture is submerged at a high stress level,significant wetting deformation may occur,and the final wetting defor-mation is greatly affected by the content of fine-particle soil in the mixture.Thus,it comes to the conclusion that,in the engineering with strict requirements for post-construction settlement,the long-term post-construction settlement due to wetting deformation should be paid more attention to.

    Selection of Input Waves in Time-History Analysis Under Bi-Direction Horizontal Seismic Action
    Yang Hong Ren Xiao-jun Xu Hai-ying
    2010, 38(11):  40-46.  doi:10.3969/j.issn.1000-565X.2010.11.008
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    Proposed in this paper are two methods to select the input waves under seismic action,one is SRSS method and the other is dual period method.The two methods,fitting the target design response spectrum with the SRSS spectrum in the response spectra of two horizontal earthquake components,refer the notion of selecting input earthquake waves for three-dimension analysis in American codes ASCE/SEI 7-05 and FEMA 368,and integrate with the dual frequency interval method of two-dimension analysis used in China.Then,by taking three spatial frames as examples,and by using the maximum elastic base shear under frequent earthquake,as well as the maximum elasto-plastic top displacement and elasto-plastic inter-story drift angle under rare earthquake as the structural response indicators,the selecting and controlling effects of the two proposed methods are compared and analyzed.The results show that the deviation of the maximum elastic base shear obtained by the dual period method is lowest,that the deviations of the maximum elasto-plastic top displacement and the maximum elasto-plastic inter-story drift angle obtained by the SRSS method and the dual period method are lower than those obtained by the dual frequency interval method,and that the dual period method controls the structural response indicators more comprehensively and effectively.

    Calculation of Shear Strain Energy for Diaphragms and Side Walls of Single-Box Double-Cell Box Girder
    Zhao Jia-jian Wei De-min
    2010, 38(11):  47-53.  doi:10.3969/j.issn.1000-565X.2010.11.009
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    According to the sectional deformation of single-box double-cell box girder,some displacement parameters are designed,and the displacement modes of horizontal and vertical distortion angles of the cross-section are deduced.Then,the calculation diagrams of diaphragms and side walls are simulated by using rigid frames or plates,and both the shear strain energy and the shear stiffness of diaphragms and side walls are deduced based on the principles of mechanics and finite element.Finally,the proposed method is compared with the commercial finite element software.It is found that the proposed theory and method are both correct and complete,that the proposed method is superior to the commercial finite element software with similar calculation results,and that the shear strain energy of diaphragms and side walls increases with the displacement by a power function.In addition,the optimal opening position of diaphragms of single-box double-cell box girder is determined in this paper.

    Calculation Model of Speedup Effect of Wind Velocity in Hilly Terrain
    Wei Qi-ke Li Zheng-liang Sun Yi
    2010, 38(11):  54-58,73.  doi:10.3969/j.issn.1000-565X.2010.11.010
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    In early researches and the latest specifications of some developed countries,the exponential-law calculation models are often used to calculate the speedup effect of wind velocity at the tops of moderate hills and crests,and the parameters of different models are variable.In order to solve this problem,the influences of the slope and the height of a hill as well as the terrain conditions on the speedup effect are numerically simulated with the CFD software Fluent 6.2.According to the simulated results,a logarithmic-law calculation model of average speedup effect is proposed based on the fitting of all parameter values,which is available for steeper hills and crests.From the comparison of the proposed model and the previous model as well as the existing specifications,it is found that the proposed logarithmic-law model is more accurate than the exponential-law one in terms of the description of speedup effect of near-surface wind velocity in hilly terrain.

    Incremental-Cost Economy Model in Full Life Cycle of Water-Saving Projects for Green Building
    Chai Hong-xiang Hu Xue-bin Peng Shu-juan Wang Tian-yun
    2010, 38(11):  59-63.  doi:10.3969/j.issn.1000-565X.2010.11.011
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    By analyzing the composition of the direct incremental cost and the incremental cost in the full life cycle of water-saving projects for green building,an incremental economy model,which includes both the initial and the future cost in the full life cycle,is established in the form of net present-value measurement index,and a method to calculate the direct incremental cost is proposed.Then,the model is simulated and the method is applied to a water-saving demonstration project for green building in West China.The results show that the direct incremental costs per unit construction area in the full life cycle are respectively 21.0 yuan per square meter and 31.5 yuan per square meter,which means that the proposed model and method are both reasonable and practical.

    Chemistry & Chemical Engineering
    A Mathematical Model Describing Light-Induced Yellowing of BCTMP Based on Regression Analysis
    Chen Gang Wen Ai
    2010, 38(11):  64-68.  doi:10.3969/j.issn.1000-565X.2010.11.012
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    In this paper,first,the Bleached Chemical Thermal-Mechanical Pulps（BCTMPs） of poplar,fir and maple were irradiated with UV light to accelerate the yellowing.Then,the variations of brightness（R） and yellowing number（PC number） of these three kinds of BCTMPs during the light-induced yellowing were investigated.Finally,a model to describe the variations of brightness and PC number with the irradiation time is established based on regression analysis.Analytical results show that there is a linear relationship between PC number and b＊ and a sub-linear relationship between lg t and R as well as PC number.Experimental results indicate that the proposed model is generally applicable.

    Preparation of 5-Hydroxymethylfurfural from Glucose Catalyzed by Cation Exchange Resin and Al2O3
    Lin Lu Chen Tian-ming
    2010, 38(11):  69-73.  doi:10.3969/j.issn.1000-565X.2010.11.013
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    5-Hydroxymethylfurfural（5-HMF） was prepared from glucose,with strong-acid cation exchange resin 732 and Al2O3as the catalysts and with DMSO as the reaction medium.Then,the corresponding reaction process was investigated,and the stabilities of both the resin and Al2O3 were analyzed.The results show that DMSO accele-rates the catalytic conversion of glucose,that the glucose conversion,the 5-HMF yield and the selectivity respectively reach 90.19%,44.53% and 49.37% after a 12-h reaction at 130 ℃ with an initial glucose content（mass fraction） of 10%,and that resin 732 and Al2O3 keep stable even after being used for many times.

    Effect of Inorganic Salts on Electrostatic Layer-by-Layer Self-Assembly of Lignosulfonate
    Deng Yong-hong Wu Yuan Feng Xin-Jia Ouyang Xin-ping Yang Dong-jie Qiu Xue-qing
    2010, 38(11):  74-79,116.  doi:10.3969/j.issn.1000-565X.2010.11.014
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    Lignin multilayer films were fabricated from salt-added lignosulfonate（SL） and poly（diallyldimethylammonium chloride）（PDAC） by the electrostatic layer-by-layer self-assembly,and the effect of salt on the SL/PDAC self-assembly was studied in this work.The self-assembly process was monitored by means of UV-vis spectroscopy,and the surface morphology of the films was observed via AFM.The results show that both the ionic strength and the salt species of the SL dipping solutions greatly influence the adsorption characteristics of SL during SL/PDAC self-assembly.When NaCl is added,the adsorbed amount of SL increases,the adsorption rate reduces,and the surface roughness of the SL/PDAC self-assembled films increases with the increase ionic strength in the investigated range.At the same ionic strength,the adsorbed amount of SL increases with the cation radius when LiCl,NaCl or KCl is added,while it decreases with the increase anion radius when NaCl,NaBr or NaI is added.

    Comparison of Bleaching Performance Between Screened and Unscreened Wheat Straw Pulps
    Li Jun Wu Hui-min Xu Jun Wang Qiang Zeng Jian
    2010, 38(11):  80-85.  doi:10.3969/j.issn.1000-565X.2010.11.015
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    Screened and unscreened oxygen-alkali pulps of wheat straw were bleached via QPo and OQPo sequences,and the bleaching effects were compared between screened and unscreened pulp.Furthermore,both the characteristics of the fibers in bleached pulp and the pollution load of the effluent were analyzed.The results show that,as compared with QPo bleaching sequence,OQPo bleaching sequence may result in higher brightness,heavy viscosity loss and low yield for both the screened and the unscreened pulps;that,as compared with the screened pulp,the unscreened pulp is of higher brightness-increasing rate（up to 4.9 percentage points） and total pulp yield（up to 10.6 percentage points）;that the fibers in the screened pulp is about 0.78 mm in weight-average length,which is similar to those in the unscreened pulp,while the fiber coarseness of screened pulp is much higher;and that OQPo bleaching is more environmentally friendly than the traditional CEH bleaching because it completely eliminates absorbable organic halogens and greatly reduces CODCr and BOD5 discharge.

    Kraft Pulping of Hibiscus cannabines and ECF Bleaching of the Pulp
    Wang Qiang Chen Ke-fu Xu Jun Li Jun Tang Jie-bin Wu Hui-min Liu Shan-shan
    2010, 38(11):  86-90.  doi:10.3969/j.issn.1000-565X.2010.11.016
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    By using Hibiscus cannabines as the raw material,this paper analyzes the chemical component of the material,investigates the optimal kraft pulping（KP） conditions at different H factor,and discusses the element chlorine-free（ECF） bleaching of the KP pulp and corresponding bleaching process.It is found that Hibiscus cannabines is a good material for paper making,with the chemical composition as follows： 45.0% of nitrate-ethanol cellulose,16.5% of Klason lignin,pentosan and low content of extraction.Moreover,the results indicate that,in the optimal pulping conditions,namely,a H-factor of 1 000,an active alkali dosage of 20% and a sulphidity of 22%,screened pulp with a yield of 44.9%,a Kappa number of 20.4 and a residual alkali content of 11.67 g/L can be obtained,and that ECF bleaching sequence（ODED） can produce pulp with a brightness of 82.3%ISO when OD0,2%-EpD1,1.5% process is employed.

    Computer Science & Technology
    Graph Theory-Based Algorithm to Manage FPGA Resources
    Zhang Hong-lie Zhang Guo-yin
    2010, 38(11):  91-95.  doi:10.3969/j.issn.1000-565X.2010.11.017
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    In order to avoid the redundancy and duplication when using the plane partition algorithm to find all maximal empty rectangles,an algorithm based on virtual undigraph marked as KAMER_VU is proposed to manage the reconfigurable empty hardware resources.Based on the FPGA of two-dimension region,the algorithm uses the mapping between the undigraph and the FPGA model and indirectly finds all maximal empty rectangles by looking for effective loop and pathway in the virtual undigraph,thus simplifying the partition of free region.Some simulations are then performed to make a comparison between the proposed algorithm and the existing SL algorithm.The results indicate that KAMER_VU effectively saves time for hardware distribution and increases the success probabi-lity of hardware allocation for task.

    Fast Convergence Construction Algorithms for P-Grid Overlay Network
    Song Wei Zhao Yue-long
    2010, 38(11):  96-103.  doi:10.3969/j.issn.1000-565X.2010.11.018
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    Based on the original P-Grid construction algorithm,two improved algorithms are proposed focusing on two situations,one is the node without initial data load（Ignore-of-Load） and the other is the node with initial data load（Care-of-Load）.The proposed Ignore-of-Load algorithm improves convergence rate in the aspects of extending the path with more bits and increasing the success rate of recommendation.The three Care-of-Load algorithms,two of which respectively focus on the path and the data and another of which possesses satisfaction adjustment,are then compared.Simulated results show that the proposed Ignore-of-Load algorithm reduces number of communications by more than 50 percentage points and greatly improves the convergence rate,and that the Care-of-Load algorithm with satisfaction adjustment can also improve the convergence rate and can search data index with a success probability of about 90%.

    Improved LEM2 Algorithm for Incomplete Information System
    Xu Yi Li Long-shu Li Xue-jun
    2010, 38(11):  104-109.  doi:10.3969/j.issn.1000-565X.2010.11.019
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    In order to exceed the limitations of LEM2（Learning from Examples Module,Version 2） algorithm in processing incomplete information system,an improved LEM2 rule-induction algorithm is proposed,with the qua-lity and efficiency of rule induction being both improved.Then,based on the set pair theory,the set pair situation tolerance relation and the generalized rough set model based on the tolerance relation are introduced in the incomplete information system,and the model is combined with the LEM2 algorithm to improve the quality of rule induction.Moreover,the redundant attribute-value pair set is defined,by deleting which from the candidate attribute-value pair sets during the rule induction,the converse elimination action is successfully avoided,the convergence is accelerated and the efficiency of rule induction is improved.Finally,some simulation experiments are conducted.The results verify the effectiveness of the improved LEM2 algorithm in the rule induction of incomplete information system.

    An Approach to Fast Inferring Link State Probability Based on End-to-End Measurement
    Zhao Zuo Cai Wan-dong
    2010, 38(11):  110-116.  doi:10.3969/j.issn.1000-565X.2010.11.020
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    As a kind of prior knowledge,link state probability distribution plays an important role in inferring the accuracy of link performance state.This paper deals with the inference of internal link state probability based on the end-to-end measurement in tree topology,and defines it as a maximum likelihood estimation problem.By using a product model to describe the relationship between the path and the link state probability and by estimating link state probability via the computation of path state probability,a new approach to the fast inference of link state probability is proposed.The approach is then applied to simulation experiments.The results indicate that the proposed approach is effective and practical in inferring the internal link state probability.

    Image Segmentation Based on Adaptive External Force
    Fu Zeng-liang Ye Ming Su Yong-lin Lin Yan-ping Wang Cheng-tao
    2010, 38(11):  117-121.  doi:10.3969/j.issn.1000-565X.2010.11.021
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    In order to rapidly and accurately extract regions of interest from a complicated image,by combining the gradient vector flow and the signed-distance penalized functional,an image segmentation method based on adaptive external force is proposed under the variational level set frame.This method correctly attracts the initial contours inside outside,even across the object to the object boundary,introduces the signed-distance penalizing term to avoid complicated and time-consuming signed-distance re-initialization procedure,and employs the weighted arc length-rectifying term to make the contour to evolve continuously and smoothly during the propagation.The proposed me-thod,together with the existing Li＇s method,is finally used to segment hybrid and real medical images,the results demonstrating its feasibility and superiority.

    Availability-Enhanced Model for Job Execution in Computational Grids
    Hu Zhou-jun Hu Zhi-gang
    2010, 38(11):  122-127,134.  doi:10.3969/j.issn.1000-565X.2010.11.022
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    In order to improve the quality of service（QoS） in service grid environment,the concept of Availability-Enhanced Job Execution Service（AJES） and its constructing method are proposed for the grid environment consisting of a large amount of low-availability resources.Then,an availability-enhanced model for job execution（AMJE） is derived from AJES,which redundantly schedules the resources to one or more grid sites within AJES,thus enhancing the availability required for job execution.In AMJE,different participants on behalf of their profits are described as a game,and a balance threshold of AJES availability is obtained.Experimental results show that AMJE increases the revenue of resource providers,improves the QoS level for end users,and exhibits good adaptability to dynamic grid environment.

    Data Field-Based Method for Image Segmentation with Two-Dimension Threshold
    Wu Tao Qin Kun Ou Lei-hai Du Yi
    2010, 38(11):  128-134.  doi:10.3969/j.issn.1000-565X.2010.11.023
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    In order to correctly select the optimal threshold for image segmentation,a novel method of image segmentation based on data field is proposed.The method maps the image from grayscale space to the appropriate potential space in data field,and measures the interactions of the elements in the two-dimension histogram by taking the frequency of two-dimension gray histogram as the mass of data field,thus generating a three-dimension data field.Then,by employing the potential center elimination and combination,the optimal threshold is determined and good segmentation result is obtained without significantly increasing the time complexity.It is indicated by the experiments for standard image datasets and some noisy images that,as an alternative to OTSU,the proposed me-thod is reasonable and effective with certain noise resistance.

    An Improved RMPKC Scheme
    Yuan Feng Hu Yu-pu Ou Hai-wen Li Shun-bo
    2010, 38(11):  135-140.  doi:10.3969/j.issn.1000-565X.2010.11.024
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    As the rational multivariate public key cryptosystem（RMPKC） had been broken by an improved 2R decomposition method,this paper proposes an improved RMPKC scheme.In this scheme,the order of the function of the first rational mapping is changed to three while that of the second remains unchanged.Based on this core idea,the requirement for conducting the 2R decomposition attack is not fulfilled.Thus,the current 2R decomposition attack is effectively resisted by the improved RMPKC scheme.It is proved that the 2R decomposition attack is valid when the order of the function of the second rational mapping is changed to three while that of the first remains unchanged.

    Registration Technology Based on ICP Algorithm for Spinal Surgical Navigation
    Tian He-qiang Wu Dong-mei Du Zhi-jiang Sun Li-ning
    2010, 38(11):  141-147.  doi:10.3969/j.issn.1000-565X.2010.11.025
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    This paper deals with the registration between preoperative CT images and intraoperative physical objects in the three-dimension computer-assisted spinal surgical navigation technology,and proposes a two-step registration strategy,which realizes the registration by an electromagnetic positioning system on the three-dimension visualization platform based on Visualization Toolkit（VTK）.In this strategy,several feature points are extracted on a spine bone surface respectively in the virtual space and in the physical space for coarse registration,an electromagnetic positioning probe is used to extract points on the spine surface in physical space,and the corresponding points are extracted in the virtual space.Moreover,the ICP（Iterative Closest Point） algorithm is used to complete a fine registration.The ICP algorithm is then validated by simulation and the accuracy of it is also analyzed.Finally,a registration experiment is performed with a spine model to evaluate the accuracy of the proposed method,followed with an error analysis.The results show that the proposed registration method is simple and reliable,and that the final registration accuracy for spine model meets the finical surgery requirements well.

    Gait Planning of Humanoid Robots Walking on Slope
    Bi Sheng Min Hua-qing Chen Qiang Zhuang Zhong-jie Liu Qi-feng
    2010, 38(11):  148-154,160.  doi:10.3969/j.issn.1000-565X.2010.11.026
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    Aiming at the gain planning of humanoid robot SCUT-I,a slope motion pattern controlled by step length,step period and some other walking parameters is designed.Then,the trajectories of the pelvis and the ankles are planned based on the inverted pendulum model to achieve the slope walking pattern.Moreover,according to the model parameters of SCUT-I,the robot is modeled and simulated through Matlab 6.5.Finally,some experiments are carried out to simulate the movement of the robot on slope,and the results verify the effectiveness and stability of the proposed gait planning method.

    Mathematics
    Simulation Analysis of Power of Bootstrap Tests in Spatial Econometric Models
    Ou Bian-ling Long Zhi-he Lin Guang-ping
    2010, 38(11):  155-160.  doi:10.3969/j.issn.1000-565X.2010.11.027
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    When the error does not satisfy the assumption of normal independent distribution,the spatial correlation test based on the asymptotic distribution of Moran＇s I test statistic suffers weak power.In order to solve this pro-blem,Bootstrap methods are applied to the Moran＇s Ⅰ statistic for spatial correlation test in the spatial econometric model.The results of Monte Carlo simulation indicate that the Bootstrap test is as effective as（even better than） the asymptotic test when the error satisfies the i.i.d.normal distribution;that the Bootstrap test effectively improves the power of asymptotic test when the error does not satisfy the i.i.d.normal distribution and is heteroscedastic;that both the spatial correlation coefficient and the spatial contiguity structure significantly affect the power of Bootstrap test with small sample scale,especially,under the Queen matrix with dense spatial contiguity and the spatial correlation coefficient less than 0,the power of the Bootstrap test is obviously higher than that of the asymptotic test;and that,when the spatial weight matrix is the Queen matrix,the power curve of the Bootstrap test changes from ＂√＂type to ＂V＂ type,with the symmetry being increased and the influence of spatial contiguity structure on the power being weakened.

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