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2007 Vol. 33, No. 09

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Investigation of force under asymmetry stator wake
Meng Yue, Li Lin, Li Qihan
2007, 33(09): 1005-1008.
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To reduce the forcing response of rotor blades due to the wake of front stator vane, a study of front stator aerodynamic mistuned was proposed. The main aims of this article lie on following two aspects. First one explored how to simulate three-dimension rotor-stator unsteady flow field for asymmetry stator in a simplification algorithm so as to reduce calculating time and computer requirements. The other one is to analyze the force of rotor blade under the asymmetry stator wake using the simplified method. Study shows that asymmetry stator mistuned design changes the original force of rotor from single frequency and higher amplitude to more frequencies and lower amplitude, as a result, mistuned design reduces the wake force on rotor efficiently.
Hot-firing tests and numerical simulation of aerospike nozzles
Wang Changhui, Liu Yu, Liao Yunfei
2007, 33(09): 1009-1012.
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Hot-firing tests and numerical simulation were carried out on a 3-cell GH2/GO2 linear aerospike nozzle engine with round-to-rectangle primary nozzles. Test apparatus, structures and design parameters of the main parts concerned with the experimental engine were described. Data measured in the tests, experimental photograph and data analyses were presented. Aerospike nozzle flowfield was studied by numerical simulation and efficiency altitude characteristic of experimental aeropike nozzle engine was also predicted. The primary nozzle and inner layer of the combustion chamber were made of ablation-resistant W-Cu alloy and the aerospike ramp was made of steel. Detonation wave igniter was attempted to use on multi-cell aerospike nozzle and two short-duration hot-firing tests on the aerospike engine without generation cooling were executed successfully. The aerospike nozzle performance was obtained under two CNPR which is the the ratio of combustion chamber pressure to ambient pressure. It is shown that good altitude compensation of thrust and high efficiency was yielded in the tests. Near CNPR=50, efficiency is 92% to 93.5% and efficiency is 95% to 96% near CNPR=350. The promising efficiency of more than 98% at design point can be expected.
Rotordynamic analysis of whole aero-engine models based on finite element method
Chen Meng, Ma Yanhong, Liu Shuguo, Hong Jie
2007, 33(09): 1013-1016.
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In modern times, the mechanical and aero forced frequency on aero-engines become more and more intricate, so dynamical interaction of different structures should be taken into account in aero-engine vibration analysis. For above reasons, a rotordynamic analysis of a whole engine model based on three-dimensional solid element was performed using the program which could take gyroscopic moment into account on NASTRAN. An unbalance response calculation of the casing was performed to predict the transfer function (dynamic stiffness) at the bearing support, as well as their effects on rotordynamics. In the analysis of models based on different elements, the effect of corner stiffness between shafts and disks was compared, as well as the coupled vibration of disks and shafts, it is proved that various vibration modes could be accurately calculated using the whole engine model based on solid element.A phenomenon of the coupled rotor bending and casing vibration was captured, as well as the effect rule, it was showed the third rotor critical speed of the coupled rotor bending and casing vibration mode was a frequency range. The method to predict critical speeds and mode shapes of the rotor considering dynamic interaction between the rotor and casing was investigated.
Development and experiment of active member for space-base precise pointing Hexapod
Li Weipeng, Huang Hai, Bian Bian
2007, 33(09): 1017-1020.
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A platform scheme that provides precision pointing and active vibration isolation for space-base payloads based on parallel mechanism-Hexapod was proposed. With the analysis of the current Hexapod-s actuators, a high precision dual-driving hybrid actuator was developed. It integrated ball-screw actuator as macro-moving stage and piezoelectric stack actuator as micro-moving stage. Key characteristics of the hybrid actuator were measured at first, such as stroke, macro-moving stage open-loop positioning accuracy and micromoving stage dynamic property. An experiment system based on MATLAB/dSPACE environment was established and the actuator single degree-of-freedom positioning experiment and active vibration isolation experiment were carried on then. Experiment results show that the hybrid actuator stroke exceeds 50mm and its whole positioning error being less than 1μm with the close-loop compensation of the micro-moving stage. The results also show that when continuously excited at 30Hz on one end of the hybrid actuator, vibration on the other end is decreased more than 90% with the adaptive filtering active disturbance canceller (ADC) algorithm. The study indicates that the hybrid actuator is expected to apply to precise pointing Hexapod.
Experiment of solid-liquid phase change in copper foam
Zhang Tao, Yu Jianzu
2007, 33(09): 1021-1024.
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The thermal performance of solid-liquid phase change thermal storage device which embedded with copper foam was investigated. The 98％ pure Heneicosane (C21H44) was used as the phase change material (PCM), and it was filled in the copper foam through a vacuuming procedure. The PCM and the copper foam were sealed and insulated to get the test vessel. An aluminum bed plate which embedded with heating rods was used to heat the test vessel, and the temperature of the vessel was measured by some plate-type and probe-type platinum-resistance thermocouples (pt100) and collected by a data acquisition unit. The temperature variation curves under various heating power were plotted and the results were discussed. Experimental results indicate that, the thermal conductivity and performance of the phase change thermal storage device is obviously improved while copper foam as a heat transfer enhancement.
Risk probability assessment method for complex system
Ge Zhihao, Xu Haojun, Liu Lin, Meng Jie
2007, 33(09): 1025-1028.
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To assess the complex system-s risk probability while the number of the simples was limited, the small probability assessment modeling method by small simples was put forward, and the mapped relationship between the cumulating probability and the extremum of the critical parameter was approached by nonlinear function. The risk probability assessment mathematic model was developed, and the basic assessment model was obtained by using nonlinear regress. The offered simples can not completely accorder with the assessment model, so the error was regarded as the object function, and the optimum probability assessment model was presented. In order to optimize the model-s distribution parameter, the improved genetic algorithm was adopted. The applied example of flight safety assessment was showed, and the flight risk probability was calculated by the limited simples. The precise is improved by the optimum approach function.
Numerical simulation of parachute fluid-solid coupling problem and flow analysis
Wang Kan, Cao Yihua, Yu Ziwen, Pan Xing
2007, 33(09): 1029-1032.
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A new numerical simulation method for predicting parachute fluid-solid coupling problem using semi-implicit method for pressure-linked equations (SIMPLE) algorithm is proposed. The both coupling computation and flow field analysis during terminal descent stage are proved efficient through sample analyses using this new simulation method. The simulations of a flat circle parachute and a cone-shaped parachute suggest a fine efficiency and good stability of the new method. The test problems for the new method are about the terminal descent stage, since the ordinary numerical simulation method(the parallel finite element method) is general used in this field. Comparing with the result gained by the parallel finite element method. The results of the new method are also proved accurate and reasonable. Flow field characteristics at various angles of attack are further simulated for the cone-shaped parachute model. The new method is an alternative and a complement to the ordinary numerical simulation method.
Effectiveness evaluation for air-combat of airborne fire control system
Guo Jinyuan, Huang Jun, Yan Bingxin
2007, 33(09): 1033-1035.
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The effectiveness evaluation of airborne fire system is a vital part of airplane-s effectiveness evaluation on combat. A modeling method that combined the theories of influence diagrams and Lanchester equation was applied to build the air-combat model of airborne fire control systems. The damaging ratio of air-combat for different airborne fire control systems, which reflected fire control system-s influence on air-combat dominance, was computed. The curves were drew about how the performance index of fire control systems (targeting error, identifying probability, and attacking time) affected air-combat damage ratio. This method provides credible basis on how to improve the arming of airplane-s fire control system. This model lays a foundation on evaluating airplane-s air-combat effectiveness and makes some sense on commanding practical combat.
Attack helicopter gun recoil compensation control system design
Yu Zhi, Shen Gongzhang
2007, 33(09): 1036-1040.
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The recoil force from attack helicopter gunfire would cause the change of kinetic parameter of the carrying aircraft, and further affect the firing accuracy of weapon. Actually it is of a phenomenon on disturbance response. In order to reduce this recoil effects, a gun recoil compensation control framework based on nonlinear H∞ method was put forward. First, according to the six-degree-of-freedom motion equations, the anticipated force and moment commands were derived by solving the Hamilton-Jacobi partial differential inequation. Then on the basis of helicopter aerodynamic force and moment formula, the anticipated commands were approached by using iterative algorithm until getting actual blade pitch commands. Finally the simulation was carried out with the combination of the flight control system and gun recoil parameters. It-s indicated that the control system can achieve good performance and stability robustness, and effectively attenuate the disturbance to aircraft.
Method of signal processing in weigh-in-motion of vehicles
Wu Jie, Fei Yuhua, Yu Jinsong, Wan Jiuqing
2007, 33(09): 1041-1045.
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Based on the concept of inverse model, an adaptive inverse filter (AIF) was employed which could suppress noise within the bandwidth of the desired signal. Within the framework of the finite impulse response (FIR) filter, the inverse system of weigh-in-motion (WIM) system was constructed by using least mean square (LMS) adaptive algorithm as an innovative filter. Moreover, for the sake of best improving measurement accuracy, as a noise filter, a low-pass (LP) filter dedicated to restrain noise out of the bandwidth of useful signal was adopted. After processed by cascaded filter combination, namely, AIF filter and LP filter, obtained results, compared with those processed by the approach of parameter estimation, show a significant improvement in estimation of static weight of moving vehicles.
Dead band nonlinearity of digital closed-loop FOG
Jin Jing, Zhang Chunxi, Song Ningfang, Li Lijing
2007, 33(09): 1046-1050.
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Dead band nonlinearity is one of nonlinearity errors in digital closed-loop fiber optic gyroscope (FOG). Output noise and drift of FOG can be reduced by attenuating dead band nonlinearity. Based on the definition of the resolution and threshold for FOG, a dead band definition and test method in digital closed-loop FOG were proposed. The frequency and phase characteristic of interfering signal and the process that the interfering signal tracked and locked input signal were analyzed to prove that electrical crosstalk between phase modulator and photodetector and modulation error were main interference sources causing dead band. A dead band model of digital closed-loop FOG was developed by combining an ideal digital closed-loop FOG model and a partial integration model of interfering channel, and a condition expression of dead band and an expression of output error produced by dead band were derived from the dead band model. The simulation results of the dead band are identical with the experimental results of the dead band, which indicate that the dead band model of digital closed-loop FOG is accurate.
Adaptive fuzzy sliding mode control for reaction-jet and aerodynamics compound control missile
Wu Zhenhui, Dong Chaoyang
2007, 33(09): 1051-1055.
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A missile autopilot design method based on adaptive fuzzy sliding mode control (AFSMC) was proposed for reaction-jet and aerodynamics compound control missile with nonlinearity and strong coupling. The universal approximation ability of adaptive fuzzy system was used to approximate the nonlinear function in missile dynamics equation during the flight of high angle of attack. And because the sliding mode control was robustness to external disturbance strongly, the sliding mode surface of the error system was constructed to overcome the influence of approximation error and external disturbance so that the actual overload can track the maneuvering command with high precision. Simulation results show that the missile autopilot designed in this paper not only can track large overload command with higher precision than traditional methods, but also is robust to model uncertainty and external disturbance strongly. After employing the reaction-jet and aerodynamics compound control, the aerodynamic fin deflection is decreased greatly. Therefore, the aerodynamic fin deflection saturation is avoided.
Recognition method for tactical maneuver of target in autonomous close-in air combat
Zhong Youwu, Liu Jiarun, Shen Gongzhang
2007, 33(09): 1056-1059.
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A two-stage recognition system was proposed for recognizing tactical maneuvers of target in autonomous close-in air combat, which included basic maneuver recognition and combinatorial maneuver recognition. Basic maneuvers were identified in first stage by fuzzy inference method. The chatter of outputs was smoothed by ‘mode memory- modeled upon the pilot reasoning process. Combinatorial maneuver recognition in second stage used parallel timed automata architecture, which was of excellent expansibility and robustness, to extract the primary geometry features of combinatorial maneuvers from sequences of basic maneuvers. The recognition system was validated by simulation. The result indicates that the recognition system can identify tactical maneuvers of target effectively.
Study on distributed active control of fluid pulsation in hydraulic piping
Ouyang Pingchao, Jiao Zongxia, Liu Hongmei
2007, 33(09): 1060-1063.
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Periodic fluid pulsation in aeroplane hydraulic piping could induce fluid-construction vibration and lead to fatigue damage. It is impossible to find the error sensor′s optimization location because of the pressure standing wave, and the pulsation attenuation effect is not perfect when adopting pulsation attenuation at single point. For this reason, a distributed active control method of fluid pulsation was presented. To avoid stationary point in all aviation states, several fluid pulsation actuators and error pressure sensors were placed along the piping. The second fluid pulsation produced by actuators can counteract the primary pulsation brought by aviation piston pump and make the mean pulsation of whole piping minimum when adopting adaptive feedforward control and the filtered-X least mean square( LMS) algorithm. In order to validate the vibration attenuation effect, a test platform was designed and built. Experiment results show that the distributed pulsation active control method adopted in the paper can attenuate the fluid pulsation effectively and the pulsation attenuation is over 10 dB.
Error analysis and integrated compensation of scale factor for MEMS gyroscope
Li Jianli, Fang Jiancheng, Sheng Wei
2007, 33(09): 1064-1067.
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In dynamic condition, scale factor error is one of the main errors for MEMS(micro electromechanical system)gyroscopes. For the sake of improving performance of the MEMS gyroscope, the physical origin of bias, nonlinear and asymmetry error of scale factor were analyzed. Based on the operational principle of MEMS gyroscope driven by the inner frame, mathematical error model of scale factor for MEMS gyroscope was designed. According to the angular velocity of gyroscope, the method to compensate scale factor was proposed so as to eliminate scale factor error caused by angular rate. The experimental results show that the scale factor original error of gyroscope is 4053.2(°)/h(1 σ ) and error compensated by the integrated compensation method is improved to 79.0(°)/h(1 σ ).Compared with the methods of least square and segmented compensation, the precision of gyroscope compensated by the integrated method is improved 15.4 and 7.5 times respectively. The accuracy of the theories model is verified and a theoretical foundation for future practical application is provided.
Algorithms of tasks scheduling in parallel test based on graph coloring theory
Li Xin, Shen Shituan, Lu Hui
2007, 33(09): 1068-1071.
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The test method of most automatic test systems is serial at present, so test efficiency is very low. For this problem, a relation model of test tasks was established based on graph theory. The relation between test tasks and instruments was described by "graph", so the project problem of test tasks scheduling was transformed into mathematics problem about graph theory. Based on the relation model, two algorithms named CTG and CTG-T about tasks scheduling were proposed. By using these algorithms the tasks grouping scheme that has the maximal parallel degree or the shortest test time was found, and parallel test was achieved effectively. The two algorithms were based on graph coloring theory and their correctness and feasibility were approved by both theory and emulator. These algorithms were validated by experiment in actual system and the result shows that test efficiency of system is enhanced greatly.
Survivability of SCI network topologys
Liu Xingchun, Shao Bo, Li Zheng
2007, 33(09): 1072-1076.
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For the need of the avionics, the survivability of SCI (scalable coherent interface) networks′ structures which may suitable for the avionics was studied. Some distributed switch topologies were selected, such as torodial mesh and wrapped butterfly structures, which are made by the double-node or the skip-a-node SCI node structure and may suitable for SCI networks that will have high survivability. While, comparied with the structures mentioned above for survivability of different structures, two new structures designed were also selected. Both nodes and edges destroyed were considered in this situation. The calculation and analysis of the connection relation were done using the adjacency matrix according the theory of graph. Some types of topologies which has high connection relation were found. The conclusion that changing the direction of ringlets in a same structure can influence the survivability can also be obtained.
Development of optoelectronic planar position system used to measuring position and attitude of the large construction
Wang Guodong, Li Yunhua, Li Chao
2007, 33(09): 1077-1081.
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The characteristics of now used push-bridge construction system were analyzed, and the main disadvantages of the construction system were pointed out. Aimed at those problems, a new planar position system was developed, which was composed of laser beam, photoelectric target and MCU based data acquisition system. The layout of the optoelectronic components on the optoelectronic target was optimized by the genetic algorithm. In order to test the system, a set of serial communication software was developed. There are two achievements of the optimizing. The first is that the dense in the central and sparse in the edge layout on the target is fit for control system, and the second is that the interface circuits were reduced from 144 sets to nearly 10 sets. The test result of the whole system shows that the measure range is about 200mm×100mm, the position precision is 5mm, ant the sampling time is 20ms. It can real-timely measure an object on-line which moves on a plane, and the system is adopted to be applied to the automatic control in construction projects.
Multisensor dynamic bias estimation with earth-centered earth-fixed coordinate system
Li Da, Li Shaohong
2007, 33(09): 1082-1085.
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Registration is the necessary process of data fusion of multisensors system. A new registration algorithm was presented to estimate sensor biases with earth-centered earth-fixed (ECEF) coordinate system. This algorithm was used to correct dynamic systematic errors, and improved estimation performance by considering the effect of the geometry of the global. It was accomplished by constructing pseudomeasurements of the sensor biases based on local tracks, while the pseudomeasurements with additive noises that are zero-mean, white and with easily calculated covariances. Then the sensor bias estimates were obtained dynamically by using sequential process of Kalman filter (SKF). The algorithm could also be used for constant system biases estimation after some simple modification. Finally, Monte Carlo simulations were employed to evaluate the performance of the proposed algorithm, the result shows it can solve the registration problem effectively.
Model-driven intelligent form system frame oriented to fields
Tang Wenzhong, Mo Weidong
2007, 33(09): 1086-1089.
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Form is the information carrier in the information system. In order to improve the information system-s development efficiency, reuse the existed systems, provide a prototype system and make the business crew involved in the development of system much better, a novel development method of business model library based model-driven intelligent form system oriented to e-Government field was presented. The whole framework of the form model definition module using XML and the form model processing engine using web services and MBean based on a loose coupled structure were designed. The traditional form development methods and intelligent form systems on the market were analyzed. The method exploits the idea of software reuse and MDA (model driven architecture) thoughts in software engineering field; it-s built on the field-oriented modeling, and referenced from some existed intelligent form systems. Detailed introduction of the process and characteristic of the method was also given.
Robust proximal support vector machine
Liu Yun, Tang Fagen, Lin Guangyan
2007, 33(09): 1090-1093.
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Since proximal support vector machine(PSVM) is susceptible to uneven class sizes and is sensitive to outliers and noises in the training set, a robust PSVM was proposed. By imposing fuzzy memberships to each data point and introducing different error penalties for different classes, the robustness of PSVM was greatly enhanced. Both the affinity among samples and the relation between a sample and its class center were considered when calculating fuzzy memberships. Moreover, the similarity between the algorithm and ridge regression model was well demonstrated. Experiment results show that the robust PSVM has demonstrated enhanced classification ability.
Auto-construction algorithm of four-dimensional(4D) geological stratum on complex geological structure
Zhang Junan, Liu Ruigang, Yang Qin, Jin Maozhong
2007, 33(09): 1094-1098.
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Geological modeling is widely used in the fields of oil exploration and mineral resource exploitation. With the analysis of current constructing method of stratum, the 4D geological modeling method based on morphing algorithm was addressed. The faults spatial relation binary tree and spatial morphing fields were built, then the scatter points of stratum were restoring morphed to the original geological state and the 4D stratum of time t was constructed by rupture morphing the stratum-s original geological net. Examples were given to demonstrate the validity of the algorithm. The algorithm can construct the 4D stratum automatically without interactive edit and is used in several fields such as oil forward modeling and underground water modeling.
Schedule planning method based on process modeling
Gao Juntao, Zhang Li
2007, 33(09): 1099-1102.
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To make the complexity of the schedule planning for large project lower, a new method was proposed to make project schedule plan based on process modeling. After analyzing the interrelationships between process model and project schedule plan, the concept mapping rules between them were presented to implement automate conversion between process model and project schedule plan. Because "redo" often occurs in large project that make schedule planning difficult, a repetition tasks linearization algorithm was proposed. The algorithm introduced learning curve concept to simulate the learning effect in repetition tasks in order to make schedule plan more precise than that of before.
Policy and traffic classification based MPLS explicit routing algorithm
Huang He, Li Peng, Li Weiqin
2007, 33(09): 1103-1106.
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An explicit routing algorithm based on policy and traffic classification was proposed. The algorithm was implemented in two steps: offline and online computation. The process of offline computation outputted the bandwidth for each type of traffic flow and the algorithm was based on multi-commodity problem, which got the minimum network resource consumption while meeting the bandwidth demands for all kinds of traffic flows in the network. The process of online route computation outputted the shortest path for each flow according to the pre-allocated bandwidth values of the offline process. The combination of offline and online computation mapped the traffic flows to the network topology according to the traffic distribution property, and thus could alleviate the performance degeneration problem existing in the traditional routing algorithms. The network traffic distribution state, resource situation and network management policy were taken into consideration in the process of explicit route computation, which could improve the utilization of network resource and provide the explicit route for facilitating MPLS traffic engineering and traffic control effectively.
File migration strategy based on energy model in heterogeneous storage system
Huang Heqing, Song Xiaohua, Cao Yu
2007, 33(09): 1107-1111.
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File migration strategy in heterogeneous storage system is needed with low migration cost, high efficiency and strong adaptability. Study current file migration strategy, a new file migration strategy based on energy model was presented. The energy model was developed to describe the data access load on the storage units. The energy model was developed to describe the file access rate on storage units. The random early migration scheme was proposed to reduce the performance decline caused by the skewness requests in heterogeneous storage system. The new file migration method based on data access was used to minimize the migration cost. Simulation experiments were performed to prove the efficiency of the file migration strategy based on energy modle. The experimental results show that, compared to the traditional disk cooling strategy, the averagy file access response time and system throughput of the new strategy are higher than that of the traditional disk cooling strategy by about 15%~20%.
Precisely license plate locating algorithm based on edge and color information
Zeng Lihua, Li Chao, Xiong Zhang
2007, 33(09): 1112-1116.
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A precise license plate locating algorithm was proposed combined with the mathematical morphology to solve the problems of existing locating algorithms such as low locating rate and slow speed. The algorithm was based on edge detection and color information. First color-image was preprocessed with grayscaling, smoothing and gray stretching and so on, then vertical edges detection and binarization were implemented on the image. After that linear filtering algorithm was adopted to filter disturbing edge lines, and up-down plate edges were located utilizing the characteristic of plate area′s variety in gray scales. Isolated points of the up-down edges located plate were filtered by using a point density filtering algorithm, then the plate area was located coarsely by finding connected components with adopting the mathematical morphology. Finally the plate was precisely located through color segmentation in HSV space and incline rectification. The experimental results show that this algorithm can locate the plate precisely and quickly.
Simulation and experiment of cylinder shell structure dropping into water based on fluid structure interaction
Li Fei, Sun Lingyu, Zhang Guangyue, Kang Ning
2007, 33(09): 1117-1120.
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When dropping into water from the air, large cylinder shell structures may suffer larger deformation or collapse due to the strong water impact. To improve the structural crashworthiness, the simulation was done, combined with corresponding experiments. Through the static tensile and dynamic SHPB tests, the nonlinear constitutive relationships of alternative materials were obtained, and the corresponding plastic-kinematic material models were built. Simplified models scaled 1∶ 10 were dropped into water for test, and their simulation was done also. Full sized structure in detail and partial fluid domain were modeled, composed by thin-shell, water and air. Based on the ALE/Lagrange penalty function coupling algorithm without erosion, the process dropping into water was simulated by finite element method(FEM). Then the weakness of original design was found, and an improved scheme was proposed and verified by simulation. The proposed approach is also applicable for other fluid impact problems related to large deformation and nonlinear.
Bezdek type fuzzy attribute C-means clustering algorithm
Liu Jingwei, Xu Meizhi
2007, 33(09): 1121-1126.
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Bezdek type fuzzy attribute C-means clustering algorithm(FAMC) was proposed by extending attribute means clustering(AMC) algorithm based on fuzziness index (or weighting exponent) m. The iterative algorithm was derived and the effect of fuzziness index m on objective function convergence was discussed. The experimental results of pattern recognition performances on standard Iris database and tumor/normal gene chip expression data demonstrate that FAMC is more effective than fuzzy C-means clustering(FCM) algorithm and AMC.
Parallel solution of upper and lower bounds on eigenvalues for uncertain structures
Zhang Xu, Qiu Zhiping, Hu Juxi
2007, 33(09): 1127-1130.
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When the structure parameter contains uncertain information and uncertain features in the practice engineering, the inherent frequency of the structure is also uncertain. Then the generalized solution method of the interval eigenvalue problem that for the uncertain dynamic structure need to be considered. Based on the Deif′s solution theorem for standard interval eigenvalue problem, and through the interval analysis, the upper and lower bounds of the structure eigenvalues could be transformed into two generalized eigenvalue problems to deal. For avoiding the disadvantages of the interval vertex solution method of the structure eigenvalues, such as large calculation and much runtime of the vertex solution, the parallel algorithm which could be used in largescale computing was presented. Based on the solution of the parallel analysis, it can be concluded that the parallel algorithms can solve many large scale interval problems which can not be resolved by traditional serial algorithm.

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