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15 July 2006, Volume 27 Issue 7 Previous Issue    Next Issue
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Robust H∞ control for a class of uncertain singular systems Yin, Yu-Juan (1); Zhao, Jun (1) 2006, 27 (7):  709-712.  DOI: - Abstract ( 173 )   HTML   PDF (1775KB) ( 442 )   The problem of quadratic stability is considered for a class of uncertain singular systems with norm-bounded perturbation. By transform method, the problem of control with H∞ performance index becomes a corresponding robust H∞ stabilization problem for augmented uncertain singular system. Thus, it is proved that the normalization and robust H∞ stabilization via PDSF for uncertain singular system are equivalent to the robust H∞ stabilization via PSF. Based on LMI method, the design of robust H∞ controller is given with the validity of relevant theorems illustrated by a numerical example. References | Related Articles | Metrics

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Robust controller for a class of uncertain fuzzy switched systems Yang, Hong (1); Zhao, Jun (1) 2006, 27 (7):  713-715.  DOI: - Abstract ( 211 )   HTML   PDF (134KB) ( 515 )   The robust control of a class of uncertain fuzzy switched systems is presented for an uncertain fuzzy system. Using switching technique and Lyapunov function method, a continuous state feedback controller is built to ensure the asymptotically stable closed-loop system for all allowable uncertainties, with the switching law designed to implement the global asymptotic stability of uncertain fuzzy switched systems. In this model, each and every subsystem of the switched system is an uncertain fuzzy one to which a common PDC(parallel distributed compensation)controller is proposed with its main condition given in a more solvable form of convex combinations. Such a hybrid control system is highly robust to varying parameters. A simulation shows the feasibility and effectiveness of the design method. References | Related Articles | Metrics

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Robust stabilization control for generalized periodically time-varying uncertain descriptor systems Su, Xiao-Ming (1); Wang, Gang (2); Lu, Ming-Zhu (2) 2006, 27 (7):  716-719.  DOI: - Abstract ( 256 )   HTML   PDF (161KB) ( 551 )   Based on the results of Lyapunov inequality and a necessary and sufficient condition of robust stability for generalized periodically time-varying descriptor systems, the robust stability of a closed-loop system under state feedback control is discussed with its necessary and sufficient condition given, and then the design method for a class of state feedback robust controllers is presented. Introducing the definition of quadratic stability and analyzing the relation between quadratic stability and robust stability of the systems, the necessary and sufficient condition of quadratic stability is obtained for generalized periodically time-varying uncertain descriptor systems. A numerical example is given to prove the conclusion drawn from the discussion. References | Related Articles | Metrics

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Particle swarm optimization for solving a shooting point Zhang, Da-Pang (1); Wang, Fu-Li (1); He, Da-Kuo (1); Lin, Zhi-Ling (1) 2006, 27 (7):  720-723.  DOI: - Abstract ( 232 )   HTML   PDF (844KB) ( 595 )   The particle swarm optimization is improved to overcome the difficulty in finding the shooting point of two-point boundary value problem. The key fitness function is defined as the optimization of end-point states and the running speed is improved by mapping the initial states on the end-point states in the whole process using an off-line trained neural network to form a differential equation set. A secondary search technique to upgrade searching ability is proposed to avoid the possibility of trapping search result in local extremum. After finishing the first search, all particles are renewed to enhance gradually their seeking ability in the secondary search so as to improve the hit rate of globally optimal values. An example is given to show the validity of the shooting method proposed. References | Related Articles | Metrics

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Pricing digital products with cost and competition considered in electronic commerce Wu, Jun-Xin (1); Guo, Zhe (1); Wang, Jian-Hui (1); Gu, Shu-Sheng (1) 2006, 27 (7):  724-727.  DOI: - Abstract ( 257 )   HTML   PDF (1132KB) ( 604 )   Pricing digital products in electronic commerce should use dynamically a weighted linear additivity model to reflect their features especially the cost and consider the competitors' pricing policy. According to the characteristics of time/fashion/ price-dependent demand, a sale model of digital products was developed with relevant algorithms described in detail. Some simulations were conducted to maximize the profit in an on-line market. The results showed that the pricing scheme based on the model considering both cost and competition is preferable to that based on the model only considering competition or cost, and the convergence rate of optimal price and computational efficiency of the model we developed is quite applicable. The model therefore provides a feasible solution for pricing digital products. References | Related Articles | Metrics

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On-line batchwise workpiece scheduling with restriction of time interval Huo, Man-Chen (1); Tang, Li-Xin (1) 2006, 27 (7):  728-730.  DOI: - Abstract ( 219 )   HTML   PDF (921KB) ( 640 )   Studies the problem of on-line batchwise workpiece scheduling on m identical parallel machines of which the objective is to minimize the makespan, i.e., the time for finishing the last workpiece in a batch. In such a case all the workpieces arrive in batches and each batch has exactly m workpieces to which the processing time required for each one depends on the time the batch containing it just arrives. It supposes that the processing time be restricted in a time interval. When a batch of workpieces arrives we shall schedule them immediately without interruption though no information is provided for subsequent batches. An on-line heuristic listing algorithm for batchwise workpieces scheduling is thus proposed according to LPT rule by which the workpieces in next batch will be scheduled immediately if all workpieces in a batch have already been scheduled. The worst case was analyzed with the competitive ratio given. References | Related Articles | Metrics

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A microeconomics-based resource assignment model for grid computing Wang, Xing-Wei (1); Jiang, Nan (1); Wang, Jia-Lin (1); Huang, Min (1) 2006, 27 (7):  731-734.  DOI: - Abstract ( 290 )   HTML   PDF (184KB) ( 862 )   Introducing the knowledge on microeconomics into grid computing, a dual-scheme resource assignment model is therefore developed. The way the supplier s selling price affected by supply-demand relation is used to adjust consumer's occupancy of grid resource so as to support the implementation of a win-win relationship between the supplier and consumers. If the available grid resource is plentiful, the game playing scheme is used to determine the optimal resource occupancy for consumers on the bases of Nash equilibrium and Pareto optimality, with the optimal selling price determined for the supplier. If the grid resource is scarce, the bidding scheme is used to assign the grid resource for consumers. Simulation results shown that the model is feasible and efficient with favorable performance. References | Related Articles | Metrics

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A network management system applied to board-band MCSN Shang, Rui-Qiang (1); Jiang, Yue-Qiu (2); Wang, Guang-Xing (1) 2006, 27 (7):  735-738.  DOI: - Abstract ( 298 )   HTML   PDF (476KB) ( 604 )   According to the characteristics of the conventional satellite communication system, a new topological structure of multimedia communication satellite network (MCSN) is proposed with the architecture of the relevant network management system designed. Multiplex network management protocol (MNMP) is put-forward because the conventional network management protocol do not adapt to satellite network. The blue print and information flow of the network management system are also designed. The management channel defined in ATM layer insures that the network management information transfers quickly and exactly. An MCSN demonstration/verification system is designed and implemented on the basis of satellite network simulation platform to show the feasibility of the network management system designed. References | Related Articles | Metrics

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An intrusion detection model for ad hoc network Liu, Jun (1); Li, Zhe (1); Guo, Bin (1); Geng, Rong (1) 2006, 27 (7):  739-742.  DOI: - Abstract ( 282 )   HTML   PDF (191KB) ( 687 )   The issue of routing security in ad hoc network was studied. An intrusion detection model in cooperation with distributed network is proposed for ad hoc networks, based on routing protocols. Analyzing the flaws in security for different routing protocols and summarizing the rules of judging attack behavior, local intrusion detection was conducted. Each host run local IDS, and its detection result would be gathered for such cooperative intrusion detection. In this way, the detection probability increases while the false detection probability decreases. To save the resources of the entire network, an optimized configuration scheme is proposed. The AODV route protocol was taken as example to describe the working mechanism of this model of which the performance was simulated with NS2 (Network Simulation) software. Simulation results indicated that it can safeguard well the network against intruders and maintain the network performance. References | Related Articles | Metrics

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A weakly hard real-time scheduling algorithm based on RM Zhao, Ming (1); Zhao, Hai (1); Zhang, Wen-Bo (1); Sun, Pei-Gang (2) 2006, 27 (7):  743-746.  DOI: - Abstract ( 281 )   HTML   PDF (188KB) ( 596 )   Defining the periodic task model for weakly hard system, the PV-RM scheduling algorithm is presented on the basis of RM scheduling policy. By virtue of predicting the future tasks, PV-RM can adjust dynamically the priority of task by switching over its running state between P segment and Y segment in accordance to urgency. Once the tasks overload the system, PV-RM will provide the more important tasks having higher initial priority with the service to satisfy their weakly hard real-time restriction, and provide best-effort service to other tasks having lower initial priority. Schedulability analysis and schedulable judging inequation of the PV-RM are also presented, and the validity of the algorithm is illuminated by analyzing examples. References | Related Articles | Metrics

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R&D of a pulse oximeter based on WPAN Xu, Jiu-Qiang (1); Zhao, Hai (1); Sun, Pei-Gang (2); Yin, Zhen-Yu (1) 2006, 27 (7):  747-750.  DOI: - Abstract ( 240 )   HTML   PDF (164KB) ( 742 )   A highly sensitive pulse oximeter is developed for oxygen saturation of blood on the basis of WPAN. Describes in detail the conceptual design and construction of the oximeter system especially. Firstly, the pulse oximeter's design and structure is introduced in detail. Then, the functions and design of its mobile sample acquisition terminal and construction of its main station. In addition, the division of software platform and functional modules is illustrated. With the highly developed IC/communication technologies and mature metering technique, the new pulse oximeter upgrades its conventional functions and widens its application scope, thus enhancing greatly its practicability, convenience and manageability. References | Related Articles | Metrics

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Monte carlo method for K-residual connectedness reliability based on reliability preserving reductions Sun, Yan-Rui (1); Ma, Yu-Jie (1); Zhang, Xiang-De (1) 2006, 27 (7):  751-754.  DOI: - Abstract ( 217 )   HTML   PDF (163KB) ( 428 )   Discusses the estimate of reliability of a network with unreliable nodes. Proposes the principle on which the reduction is available to the K-terminal networks with unreliable nodes in series/parallel. Applying the principle to the Monte Carlo method with RVR(recursive variance reduction), an unbiased and efficient reliability estimating method is obtained, which depends on the decomposition of state space and reduces recursively the sampling test in original state space to that in subspace. Before the sampling test in subspace, reliability preserving reductions are performed so as to enable some sampling action not to be done in subspace with corresponding variance to be 0.The validity of the algorithm is verified by testing results. References | Related Articles | Metrics

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Influence of frequency on magnetic field distribution and meniscus in rectangular soft-contact EMCC mold Zhang, Lin-Tao (1); Wang, En-Gang (1); Deng, Yuan-An (1); He, Ji-Cheng (1) 2006, 27 (7):  755-758.  DOI: - Abstract ( 222 )   HTML   PDF (247KB) ( 496 )   The distribution of magnetic induction in rectangular soft-contact mold during electromagnetic continuous casting (EMCC) was investigated considering the electric frequency. The low-melting-point Sn-Pb-Bi alloy was used as simulacrum to investigate the distortion of meniscus. The results showed that the magnetic induction in mold decreases with increasing frequency while the changing frequency does not affect the uniformity of distribution of magnetic induction. The height of meniscus is in inverse proportion to the frequency, i.e., the higher the frequency, the more stable the meniscus. Actually to ensure the effect of soft-contact continuous casting, the power input should be increased to compensate the decrease in exciting current if the frequency increases. References | Related Articles | Metrics

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Influence of casting speed on temperature field in molten pool during twin-roll strip casting Zhang, Xiao-Ming (1); Zhang, Jun-Feng (1); Liu, Xiang-Hua (1); Wang, Guo-Dong (1) 2006, 27 (7):  759-762.  DOI: - Abstract ( 246 )   HTML   PDF (924KB) ( 585 )   Based on a 3D finite element analysis of thermally coupled flow modeling the twin-roll strip casting of stainless steel, the boundary conditions of the heat exchange between rolls and molten pool are analyzed inversely. The result shows that the thermal conductivity between rolls and molten pool increases with casting speed, and the solidifying end-point moves to the exit of casting mill. Moreover, the surface and center temperatures of strip both increase and the surface temperature of molten pool slightly increases. With the size of submerged nozzle kept constant, a higher lateral temperature difference will be observed on the strip if the casting speed is too low. So, the casting speed plays an efficient role in readjusting the molten steel surface level in pool and rolling force. References | Related Articles | Metrics

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Influencing factors on finishing temperature of strip during continuous hot rolling Gong, Dian-Yao (1); Xu, Jian-Zhong (1); Liu, Xiang-Hua (1); Wang, Guo-Dong (1) 2006, 27 (7):  763-767.  DOI: - Abstract ( 819 )   HTML   PDF (262KB) ( 1956 )   A simulation software was developed to research the finishing temperature of hot strip rolling, based on conventional heat transfer model. How the seven factors affect the finishing temperature of strip were systematically analyzed, including it's rolling threading speed, exit temperature of rough rolling, inter-stand thickness change, heat exchange coefficient when water cooling, the material of work roll, temperature of work roll and ambient temperature. Among them the first five were regarded as key factors. The computation accuracy of the simulation software is as high as checked and proved by the data measured actually. Thus the software provides the theoretically the reference for developing a high-accuracy on-line control model of strip temperature during continuous hot rolling. References | Related Articles | Metrics

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Thickness target function method for load distribution during hot strip rolling Jiang, Xiao (1); Hu, Xian-Lei (1); Liu, Xiang-Hua (1); Guo, Li-He (2) 2006, 27 (7):  768-770.  DOI: - Abstract ( 254 )   HTML   PDF (171KB) ( 605 )   Analyzing the defects of conventional solution to the set of nonlinear equations of rolling load distribution, a new method named thickness target function is proposed, i.e., a monotone function is derived between total load and target strip thickness at exit, and then the target thickness is given so as to solve nonlinear equations to obtain all the pass reductions. Thus, the method can avoid the strict constraint on initial load distribution rate and deal properly with the possible abnormality that in the iterative process a work piece at exit is thicker than at entry when passing a gauge reduction during rolling. An optimization calculation was done by the method in combination with in-situ data, and the results showed that the method is accurate and rapid in operation and meets the requirement of on-line real-time control. References | Related Articles | Metrics

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Self-learning of gauge control model for plate rolling Wang, Zhao-Dong (1); Tian, Yong (1); Zhao, Zhong (1); Wang, Guo-Dong (1) 2006, 27 (7):  771-774.  DOI: - Abstract ( 411 )   HTML   PDF (390KB) ( 808 )   According to the characteristics of plate rolling, a more reasonable mill spring model and rolling force model are developed for the reform project of 2 500 mm finishing mill in Nan Steel. Considering that the high precision of the mill spring model and its self-learning is independent of the rolling force model, the self-learning is implemented first in the mill spring model as modification. Then, the workpiece gauge at exit is computed by the modified mill spring model used to implement the self-learning in the rolling force model where the short-term self-learning is used to correct the workpiece hardness coefficients of different batches, whereas the long-term one is to correct those of different steel grades. In this way, the cumulative results of short-term self-learning become the data source for subsequent computation. The method are kept and listed in database for subsequent computation. The method proposed was applied to the Medium Plate Mill Nan Steel, by which the hit rate of plate gauge control was increased by 13.3%. References | Related Articles | Metrics

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Fuzzy-decision-based design of liquid level control system for rolling caster mold Cao, Guang-Ming (1); Wu, Di (1); Zhang, Dian-Hua (1) 2006, 27 (7):  775-778.  DOI: - Abstract ( 245 )   HTML   PDF (905KB) ( 576 )   Considering several influencing factors on molten steel level in pool and the actualities of the rolling caster used, a relevant control was developed including the hydraulic actuating mechanism. The analysis of the molten steel level control system for the rolling caster mold that the process of controlling molten steel level is time-varying, nonlinear and multi-interferential. Thus, the process control theory and fuzzy control technology were applied to the automation of the control system, i.e., the control strategy combined the fuzzy decision with conventional control. Then, the fuzzy-PID control system was designed with the rules of fuzzy control given. Simulation results showed that the control system is highly stable and accurate. References | Related Articles | Metrics

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FEM analysis of strength of automotive wheels made from ultra-fine grain steel Wang, Ning (1); Du, Lin-Xiu (1); Wu, Di (1); Liu, Xiang-Hua (1) 2006, 27 (7):  779-781.  DOI: - Abstract ( 269 )   HTML   PDF (398KB) ( 667 )   To implement the weight reduction, low fuel consumption and pollution control, the new-generation ultra-fine grain steel has been used to make automotive wheel spoke instead of common high-strength steel. Static linear FEM models were thus developed to test dynamically different wheels' cornering fatigue for 3 medium-sized buses. The models can simulate and calculate the critical points in different wheel constructions and reflect the stress concentration on these points. Testing results revealed that the thickness of those wheel spoke which are made from the ultra-fine grain steel can be decreased by 2.5 mm with total weight decreased by 10 kg, and all the wheel spokes are up to standard. References | Related Articles | Metrics

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Effect of BI on viscous characteristics of mold powder Liu, Cheng-Jun (1); Sun, Li-Feng (1); Wang, De-Yong (1); Jiang, Mao-Fa (1) 2006, 27 (7):  782-785.  DOI: - Abstract ( 299 )   HTML   PDF (894KB) ( 618 )   By rotating viscometer, the relationships among the viscosity, solidification temperature, activation energy of slags, R and BI are studied. Under the present experimental conditions, the viscosity, solidification temperature and activation energy of mold powder all decrease with increasing BI and, meanwhile, the effect of BI on viscous characteristics of mold powder gradually weakens. Using such regressive relationships, the effects of all components on viscous characteristics of mold powder are investigated to predict accurately the viscous characteristics of mold powder. The results show that when BI is 2.0, the viscosity, solidification temperature and activation energy of mold powder are 0.17 Pa · s, 1 030°C and 120 kj · mol-1, respectively. As known, BI of mold powder should be over 2.0 to keep the stable viscous characteristics of mold powder. References | Related Articles | Metrics

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Application of measuring electrical conductivity of cryolite-based melts by CVCC technique Wang, Zhao-Wen (1); Hu, Xian-Wei (1); Gao, Bing-Liang (1); Shi, Zhong-Ning (1) 2006, 27 (7):  786-789.  DOI: - Abstract ( 350 )   HTML   PDF (228KB) ( 1115 )   The continuously varying cell constant (CVCC) technique was verified to be feasible by measuring the electrical conductivity of standard KC1 solution. It was found that the error due to polarization resistance is very small if using CVCC technique to determine the electrical conductivity of aqueous solutions and molten salts, and no deduction of lead/electrode resistance value from read-out value required, thus simplifying the experimental procedure. The electrical conductivity of Na3AlF6-Al2O3 melts with different Al2O3 contents was measured by CVCC technique and the results were compared with the relevant data in earlier works. It was proved that CVCC technique can measure accurately the electrical conductivity of aluminum electrolyte and other high-temperature molten salts. References | Related Articles | Metrics

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Nonlinear dynamic coupling of impact/rub and oil film for a rigid rotor in short journal bearings Zhao, Chun-Yu (1); Lu, Zhong-Liang (1); Yao, Hong-Liang (1); Wen, Bang-Chun (1) 2006, 27 (7):  790-793.  DOI: - Abstract ( 221 )   HTML   PDF (325KB) ( 680 )   Discusses the nonlinear coupling characteristics of the oil film and impact/rub for a rigid rotor in short journal bearings by virtue of bifurcation diagram, Poincare mapping, and trajectory of rotor centre, supposing the impact/rub is of different intensities and the rotor is being rubbed in different directions. The numerical results show that the multifold-period bifurcation, aperiod motion even chaos are found with the increasing impact/rub intensity and the bifurcation diagram falls into two regions when the rotor is running at the interval of rotating speed that its response is period-doubling motion without impact/rub and the direction of impact/rub is far off 90° or 270° , and that the period-doubling characteristic of the rotor response remains unchanged when the direction of impact/rub is in the vicinity of 90° or 270° . When the rotor is running at the interval of rotating speed that its response is aperiodic/chaotic motion without impact/rub and the direction of impact/rub is in the vicinity of 90° or 270° , the rotor response is multifold period motion; and when the impact/rub intensity is smaller, the multiple of period in the vicinity of 90° is higher than that near 270° . However, both are down to period-doubling with the increasing impact/rub intensity, while the number of its response period increases even its response becomes aperiodic/chaotic motion if far off the two region, and the region of its period-doubling response will gradually be extended with the increasing impact/rub intensity. References | Related Articles | Metrics

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Exact evaluation of damping and frequency by laplace wavelet and PSO Zhu, Qi-Bing (1); Liu, Jie (1); Li, Yun-Gong (1); Ying, Huai-Qiao (2) 2006, 27 (7):  794-797.  DOI: - Abstract ( 248 )   HTML   PDF (167KB) ( 731 )   A new method to exactly evaluate damping and frequency is presented using Laplace wavelet and particle swarm optimizer (PSO). Taking advantage of the attenuation of the real part of Laplace wavelet to recognize the freely decaying waveforms from signal so as to recognize correctly both damping and frequency. Meanwhile, PSO is introduced to optimize the parameters of Laplace wavelet. Simulation results shown that the accuracy of this method is comparatively higher, and the adjacent modal coupling have no effect on its accuracy. References | Related Articles | Metrics

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Representation product model fitting collaborative design environment Wang, Qi (1); Liu, Yong-Xian (1); Zang, Ge-Ping (2); Guo, Kai (2) 2006, 27 (7):  798-801.  DOI: - Abstract ( 232 )   HTML   PDF (154KB) ( 492 )   In the course of collaborative design, the product model is required not only to be edited easily but available to maintain its semantic conformity. An identifier-based solid model combined with feature model is used to represent the product model fitting the collaborative design environment. The feature-based identifier of topological elements and its mechanism are presented to relate these identifiers to their features. In this product model, the semantic elements are independent relatively to topological elements but, at the same time, both are keeping in contact with each other by introducing the identifier mechanism, thus maintaining effectively the corresponding relation between the topological structures before and after modification and implementing the feature edit of product model with the conformity of model designs provided during collaborative design. References | Related Articles | Metrics

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Evaluation of comfortability during vibration on basis of annoyance rate Tang, Chuan-Yin (1); Zhang, Tian-Xia (1); Song, Gui-Qiu (1) 2006, 27 (7):  802-805.  DOI: - Abstract ( 314 )   HTML   PDF (188KB) ( 1340 )   Discussing the traditional evaluation of comfort ability during vehicle vibration, a fuzzily random evaluation model is proposed on the basis of annoyance rate for human body's subjective response to vibration, with relevant fuzzy membership function and probability distribution given. The software Matlab/Simulink is applied to developing a nonlinear vehicle vibration model with four degrees of freedom for simulation, of which the vehicle is subject to randomly irregular excitations exerted by road surface. Then, a model of annoyance rate is obtained in terms of vehicle body acceleration. Compared with the fatigue-efficiency reduction criterion in the conventional contrast with 1/3 multiple frequency internal, the validity of the newly proposed evaluation method is verified. The evaluation method based on annoyance rate can further estimate quantitatively the number of passengers who feel discomfort due to vibration. References | Related Articles | Metrics

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Building VCMM based on virtual prototype technology and measuring method Sui, Tian-Zhong (1); Zhang, Ming-Chuan (1); Cui, Hong-Wen (2) 2006, 27 (7):  806-809.  DOI: - Abstract ( 291 )   HTML   PDF (261KB) ( 577 )   In view of the development and feature of modern design and manufacture, a 2D and 4-layer VCMM (virtual coordinate measuring machine) framework is built. Then, combining it with 3D modeling system, the VCMM is developed further in ADAMS environment. At the same time, a hemispheric probe of unique structure is proposed for measurement and radius compensation, which is crucial to VCCM and simplifies greatly the measurement and data processing. Thus a rapid, precise and convenient method is provided to measure any section on the surface of shaped CAD model on VCMM. References | Related Articles | Metrics

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Determination of coal mine gob edges by EH-4 system Xu, Bai-Shan (1); Wang, En-De (1); Chen, Qing-Kai (1); Li, Wei-Qun (1) 2006, 27 (7):  810-813.  DOI: - Abstract ( 258 )   HTML   PDF (294KB) ( 783 )   Emphasizing the importance of controlling geological disaster in coal mine, the features of gob edges in highly mechanized mine and control of geological disaster due to mining are analyzed geophysically. Practical exemplifications show that when the water-richened gob causes tensile fissures, the target geographical body presents good electric conductivity, damaging laterally the homogeneity of its electrical properties and making longitudinally its gradation abnormal. So, in obviously undulated mountain area, electromagnetic surveying is efficient to poor geographical bodies and the further investigation of their lateral structure. References | Related Articles | Metrics

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3D numerical simulation of deformation and instability of high embankment with embedded box culvert in soft-base gully/valley area Rui, Yong-Qin (1); Tang, Cheng-Ping (2); Xiao, Chun-Fa (3); Kong, Wei-Xue (1) 2006, 27 (7):  814-818.  DOI: - Abstract ( 220 )   HTML   PDF (736KB) ( 842 )   A 3D numerical simulation with solution by Drucker-Prager model is proposed for the complex terrain in a gully/ valley area where the highway subgrade is soft with nonuniform thickness distribution. Analyzing the subsidence and deformation of high embankment and the damaging mechanism to it, the distortion and instability caused by the passage constructed for box culvert and highly earth-filled embankment arc discussed. In addition, some suggestions are put forward to control the unevenly and unequally thick soft-soil foundation and berm for box culvert against back pressure. The problems and effective measures to take during the design/construction of the similar road projects are therefore summed up. References | Related Articles | Metrics

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Application of principle of fuzzy closeness optimization to classification of surrounding rock in tunnel Han, Gui-Wu (1); Liu, Bin (1); Fan, He (1) 2006, 27 (7):  819-822.  DOI: - Abstract ( 212 )   HTML   PDF (307KB) ( 817 )   Several applicable methods of the stability classification of surrounding rock are discussed. Based on multi-factor taxonomy, the fuzzy theory is introduced into the classification. Because these factors have different effects on the final indices, they should be multiplied by different weighting coefficients. According to the grasped information on the geological conditions of surrounding rock, the concept of closeness and the principle of closeness optimization are introduced in to set up the fuzzy classification of rock mass so as to classify more exactly. An example is given to illustrate that the fuzzy classification is simple in computation, flexible in application and effective in practice. References | Related Articles | Metrics

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Application of ecological footprint in sustainable development of universities in shenyang Gu, Xiao-Wei (1); Wang, Qing (1); Li, Guang-Jun (1); Wang, Jun (1) 2006, 27 (7):  823-826.  DOI: - Abstract ( 217 )   HTML   PDF (827KB) ( 735 )   The component approach of ecological footprint was used to study the ecological footprints/efficiencies of 9 university campuses in Shenyang in 2003, including Northeastern University. Results show that the main components of ecological footprint for these university campuses include energy consumption, food consumption and waste disposal. The ecologically productive land area required for supporting a student on campus varied between 0.4 to 1.4 hm2 or the average ecological efficiency of the 9 universities was 0.7 to 2.5 man/hm2. Relevant policies and measures are thus proposed for these universities to enable them to achieve the sustainable development not only campus but contribute it to whole society by way of energy saving, minimizing food waste, waste recycling and ecological education. References | Related Articles | Metrics