Advanced Search

2005 Vol. 31, No. 04

  Previous Issue | Next Issue 
Display Method:
Preliminary investigation on detonation wave ignition technique
Guo Hongjie, Liang Guozhu, Ma Bin, Zhang Zhenpen
2005, 31(04): 375-380.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 896
Abstract:
The relative merits of several ignition techniques of liquid propellant rocket engine were analyzed. The feasibility of each ignition technique applicable to multi-chamber multi-run ignition system of future advanced propulsion system was discussed. The structural configurations of application scenarios of ignition techniques were considered. Preliminary investigation on detonation wave ignition technique was made and a simplified theoretically analytical model for the mixture of gaseous hydrogen and gaseous oxygen was established. The applicable schemes of the detonation wave ignition for liquid rocket engine were analyzed. The analysis results show that the detonation wave technique can product high pressure ratio and high temperature ratio by low pressure premix detonative gases. The detonation wave propagates with high mach number, and the detonation wave ignition source arrives each ignition place immediately. The detonation wave ignition technique has unique synchronic characteristic and simple structural configuration. It is suitable to multi-chamber multi-run synchronic ignition of liquid propellant rocket engine.
CMOS star sensor image acquisition and real-time star centroiding algorithm
Hao Xuetao, Jiang Jie, Zhang Guangjun
2005, 31(04): 381-384.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1475
Abstract:
Utilizing low power consumption and low-cost development performance of CMOS(complementary metal oxide semiconductor) image sensor technology, a novel CMOS star sensor image collection system was designed. Consisting of FPGA(field programmable gates arrays), SRAM and parallel ports, it can accomplish the collection, save and output of star image. By the principle of 4 connection domain image segmentation, a circuit model was designed to realize the star centroiding function of star sensor in FPGA. The model implements the real-time star location algorithm synchronously with image acquisition by adopting pipelining configuration, reduces the workload of data transmission, image tracking and recognition of RISC in data processing unit of star sensor, and improves the performance of star sensor system. Comparing with the software processing results, the functions of star sensor image collection and centroiding hardware circuits were validated.
Experimental study of static pressure characteristics at stator surface in a rotor-stator disk cavity
Zhang Chong, Luo Xiang, Xu Guoqiang, Tao Zhi
2005, 31(04): 385-388.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 800
Abstract:
Radial distribution of the static pressure at stator surface was measured in a rotor-stator disk cavity with centric inflow and two outflows. Cooling air enters at the center of the system and leaves through the holes in the rotor and clearance between rotor and shroud. The influences of disk rotational speed, mass flow rate of inlet and presence of the blade-cooling holes on the flow characteristics in the cavity were investigated. Results show that, within the ranges of the experiments, the static pressure on the stator firstly decreases and then increases along the radial direction. Static pressure is also increasing with the cooling air flow rate, but decreasing as the disk rotational speed and the numbers of blade-cooling holes increase. When the cooling air flow rate is greater, there is no an obvious core fluid rotation formed in the cavity.
Application of evolutionary strategy of research of static characteristics of liquid propellant rocket engine
Hu Wei, Zhang Zhenpeng, Zhang Lihui
2005, 31(04): 389-392.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 763
Abstract:
The mathematical models of the static characteristics of the full-flow staged combustion cycle rocket engine were presented. These mathematical models are composed of some non-linear equations. Using the conventional algorithms is very difficult to get to solution. Evolutionary strategy algorithm of solving the large dimension non-linear mathematical model was developed. It converts the problem of solving non-linear equations into the optimization problem of the solving the minimum value with constraints. The mathematical models of evolutionary strategy algorithm were built. The designs of mutation operator and recombination operator were presented. According to the experience and calculation results, the select operator was presented. The method of dealing with constraints was employed. The method is named as direct comparison proportional method (DCPM). Evolutionary strategy algorithm is applied solving the static characteristics of the full-flow staged combustion cycle rocket engine. Calculation results show that using evolutionary etrategy algorithm can research the static characteristics of the full-flow staged combustion cycle liquid propellant rocket engine.
Investigation of flow instability in rotating cavity with axial throughflow of cooling air
Tian Shuqing, Tao Zhi, Ding Shuiting, Xu Guoqiang
2005, 31(04): 393-396.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 919
Abstract:
To investigate the instability of flow in rotating cavities, the flow in a heated rotating cavity with cool air axial throughflow was numerically studied, based on the time-independent incompressible equations in rotating system, and low Reynolds K-ε turbulent model. The flows in the cavity, affected either by the Coriolis force, by the centrifugal-buoyancy force, or by both of these two forces were calculated. The results show that the Coriolis force acting as a resilience force does not lead to flow vibrating; the centrifugal-buoyancy force is the key factor causing flow instable, the Rayleigh_Benard convection flow induced by the centrifugal-buoyancy force is blended with the forced convection flow in the cavity, and it develops from stable to unstable as buoyancy force increases. With the coaction of these two forces the flow instability is enhanced, cyclonic and anti-cyclonic circulations can be observed circumferentially.
Research and implementation of web services composition runtime system
Zhang Yu, Ge Sheng, Sun Hailong, Ma Dianfu
2005, 31(04): 397-401.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 758
Abstract:
Single web services just provides limited functionality, it can’t provide enough functionalities for practical requirement. In order to solve the integration and collaboration problems of internet applications, it is necessary to compose several web services together to implement complex business logic functionality. Based on web service flow language (WSFL) and traditional workflow technology, a web services composition runtime system was proposed. The system is a multi-layered framework, which is made up with web services platform, web services composition processing engine, JMX registry and management center, remote management and control console and processing engine configuration and management tool. The processing engine executes WSFL-based processes, and remote management and control console can monitor and control the running process instances and processes’ history data. The system provides a uniform runtime environment for web services integration and collaboration.
Investigation and enhancement of cut-paste algorithm in overlapping grid
Li Tinghe, Yan Chao, Li Yuejun
2005, 31(04): 402-406.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1429
Abstract:
To solve the problem in generation of overlapping grids in CFD (computational fluid dynamics) automatically, the main characteristics and basic flow of the newly emerged cut-paste algorithm which generates overlapping grids by cutting and pasting hole fronts were investigated. The promising advantages of this algorithm were introduced, yet two main disadvantages were putted forth. In the conventional algorithm, one may gets failed in the judgement of attributes of hole-mapping cells when walls are not closed totally. It is a big obstacle toimplement of this algorithm in many applications. The undesired "orphan" cells may occur when hole boundaries expand out during the cut phase. Enhancements were made on these aspects to improve this algorithm. The new attribute judgement method for hole-mapping cells was considered and an additive step after cut phase was employed. These improvements were found to be effective, and the modified algorithm was extended to the application of self-adapted grid and DRAGON grid generation. Several complicated examples were also included to demonstrate that this algorithm becomes more stable, more automatic, and also more suitable in large applications.
Time domain Neal-Smith criterion and PIO prediction
Ning Guodong, Fang Zhenping
2005, 31(04): 407-411.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 818
Abstract:
A quantitative criterion named time domain Neal-Smith criterion(TDNS) for the evaluation of pilot-induced oscillations (PIO) tendencies in fixed-wing aircraft has been developed. The criterion is formulated in the time-domain to permit evaluation of flight control nonlinearities without assumption or compromise, and explicitly mirrors the frequency-domain Neal-Smith flying qualities criterion through the development of time-domain replicates to the frequency-domain criterion parameters. Category I and II PIO were predicted using TDNS, which is essentially based on the relationship of acquisition time and error signal of the pitch angle tracking in the closed-loop system, based on a certain fighter. The effects of rate limiting to prediction results were analyzed and a method of TDNS calculation was got, in which the root-mean squared pitch tracking error after the acquisition time and its second derivative metric are proposed as a direct indicator of PIO propensity. The results show the method is available, illustrative and efficient.
Model for structural fuzzy reliability analysis based on fuzzy random parameter
Wang Lei, Liu Wenting
2005, 31(04): 412-415.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 806
Abstract:
The research of structural fuzzy reliability theory is to set up a model for structural fuzzy reliability analysis just considering the defining fuzzy safety state. Based on the existed theory for structural fuzzy reliability analysis, a model for structural fuzzy reliability analysis accounting interval fuzziness of random parameter was presented. Thinking about the randomness and the interval fuzziness of structural parameter, the conception and expression of fuzzy probability density function was put forward. The type and method of selecting membership function of random parameter was given. A model for structural fuzzy reliability analysis accounting both interval fuzziness of random and defining fuzzy safety state was set up. The compatibility between the model for fuzzy reliability analysis and the random reliability analysis model was discussed. A example was given to verify the validity of the method. The result of the research shows that the method for structural fuzzy reliability can more completely utilize the structural parameter information.
Ergonomics implications of extravehicular activity spacesuit glove
Ding Li, Yang Feng, Yang Chunxin, Yuan Xiugan
2005, 31(04): 416-420.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 886
Abstract:
For enhancing the work efficiency of extravehicular activity (EVA) spacesuit glove, the main factors of affecting spacesuit gloves on performance were analyzed. The performance would decline quickly if the temperature of finger skin is under 15.6℃, the pressure always have significantly affects the manual performance, glove structure and figuration makes efficiency have ±50% difference, and good material can make glove joint more flexibility. The key to solve the work efficiency of the spacesuit glove was considered as the configuration and geometry size of the spacesuit glove. The means to improve EVA performance were discussed base on spacesuit glove design and manufacture and assisted devices. The methods of evaluating glove performance were introduced from strength, fatigue, dexterity, tactility, ranger of motion and comfort.
Solution of direct kinematics of 6-DOF parallel manipulators using extra sensors
Pei Baoqing, Han Xianguo, Chen Wuyi
2005, 31(04): 421-424.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1002
Abstract:
The direct kinematics problem of a 6-DOF parallel manipulator is difficult and there is usually not a unique solution. Different methods of handling the direct kinematics problem were discussed. Two common approaches to find the solution directly are using an iterative numerical procedure or using the extra sensors. Two types of extra sensors can be used, rotary and linear, but they are used in different configurations. The accuracy and complexity of the computations for the direct kinematics vary with different configurations of the sensors. Purpose is to determine how to add sensors to the manipulators, and find their number and their location, together with the procedure to get the posture of the platform. A simple configuration of the sensors was proposed together with the procedure to get the posture of the mobile platform. With the length of the 6 links and 4 rotary sensors or 3 linear sensors, posture of the mobile platform can be determined uniquely.
Orthogonal direction algorithm for global function optimization
He Linshu, Liu Gang
2005, 31(04): 425-429.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 720
Abstract:
A global optimization algorithm for function optimization named "orthogonal direction algorithm" was raised . This algorithm uses 3 times of large ranged orthogonal design to find the approximate location of the global optimization solution and then uses several times of small ranged orthogonal design to make precise approach. In each times of orthogonal design, the experimental points which detect the design space are generated according to the orthogonal table around a central point and the range of the design variables decrease gradually. After each times of orthogonal design, one-dimension search is also employed to improve search precision, the search direction is determined by the central point and the best(or worst) design points. This algorithm need less times of objective function calculation and is easy to make program. Two numerical optimization problem and a trajectory optimization problem of a rocket-powered horizontal-launched single-stage-to-orbit vehicle were solved to test this algorithm. These examples show when the peak of the objection function is less than the number of experimental points provided by the orthogonal table, "orthogonal direction algorithm" can often find the global optimization solution with small calculation.
Study on corrosion resistance of aircraft conduit connector at simulated service environment
Li Songmei, Liu Jianhua, Sun Zhongzhi, Jiang Weicang
2005, 31(04): 430-433.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 886
Abstract:
Corrosion resistance, airproof property and oilproof property of aircraft conduit connector of Cd-electroplated 45# steel were studied by a conduit connector corrosion experiment system at simulated service environment. Cd-electroplated 45# steel was placed in the solution of 6% NaCl at 90±5℃ for 5 minutes and then in the air at 60±5℃ for 25 minutes. This process was cycled for 200 times. The behaviors of surface corrosion and stress corrosion of the connectors were evaluated and the corrosion mechanism was investigated. It was not found that 45# steel was corroded in No.10 fuel. Only slight corrosion was found on the surface of 45# steel at simulated service environment. It was shown that the Cd-electroplated layer as anode plating layer on 45# steel has excellent protection to the matrix metal. The result of the experiment under the bending stress of 0.85σs indicated that the Cd-coated 45# steel has good corrosion resistance to SCC. Galvanic corrosion of LF2-M coupled with 45# steel was investigated. It was found that the galvanic current of the couple of LF2-M coupled with 45# steel is very low. The mean galvanic corrosion current is 0.185μA/cm2. It was demonstrated that the conduit of LF2-M and its connector of 45# steel can be coupled safely.
Flexible adaptive truss testbed and its optimal control experiment for vibration
Zhao Guowei, Huang Hai, Xia Renwei
2005, 31(04): 434-438.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 940
Abstract:
With dSPACE system and developed piezoelectric ceramic actuators, an adaptive truss shaped as a triangular prism was constructed as a testbed in this work. The first order natural frequency of the truss is as low as 5Hz. With the feedback signals from accelerometers on different locations of the structure, and using linear quadratic Gaussian controller based on finite element method model and parameter modification through test, the experiments and simulations of vibration control were conducted. The results show that compared to the situation without control, the vibrating amplitude of the controlled adaptive truss under an exciting with fixed frequency can be damped more than 90%, and the sustained time of vibration after disturbance can be decreased over 80% with the proposed optimal control method. The configuration of testbed is verified to be reasonable, and also the property of actuators and control modeling are valid. In simulation and experiment, the vibrating amplitudes are decreased to same value, and the difference of amplitudes decreasing processes are illuminated by the contrast of exciting processes.
Research and implementation of web services transaction process system
Yin Rui, Ge Sheng, Ma Dianfu
2005, 31(04): 439-442.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 710
Abstract:
Web services have good interoperation and can efficiently support coordination and integration of software, the process of coordination and composition needs the support of web services transaction to ensure consistent and reliable outcomes. Based on the property, principle and runtime mechanism of web services transaction; a web services transaction process system was designed and implemented. This system comprises fours part in functions: client, coordinator, participant, monitor and manager tools. Client can create and commit or cancel web services transaction, coordinator is the center that manages and coordinates the transaction, participant is the web service enrolled in the transaction, and monitor and manager tool is GUI tool provided to the administrator. Two-phasecommit protocol was used in the interaction between coordinator and participant parts to ensure the outcome’s atomicity and consistency. This system has the advantages of flexibility and practicability in transaction processing, and can meet the needs of inter-enterprise business transaction.
Bandwidth allocation for FC-AL under hard real time condition
Lin Qiang, Xiong Huagang, Zhang Qishan
2005, 31(04): 443-446.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 730
Abstract:
Fibre channel is a computer communication protocol designed to meet many requirements related to the ever increasing demand for high performance information transfer. Arbitrated loop is one of basic fibre channel topology. To guarantee message deadlines for the whole message set, the real-time characteristics of fibre channel arbitrated loop was studied. A real-time system is required to complete its work and deliver its services on a timely basis. The periodic task model is a well-known deterministic workload. With its various extensions, the model characterizes accurately many traditional hard real-time applications. A simple operational definition was adopted. The job is a hard real-time job. Theuser requires the validation that the system always meet the timing constraints.Under the access fairness algorithm of arbitrated loop,a bandwidth allocation scheme based on the traffic load balance of each node was proposed. The bound of the worst case achievable utilization for the scheme was derived and formally proved.
High speed and accuracy position measuring method based on inductosyn
Chen Jingquan, Er Lianjie, Liu Zhenghua, Wu Yunjie
2005, 31(04): 447-450.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1157
Abstract:
Position measurement methods by use of phase detection and amplitude detection based on inductosyns are not suitable for high speed and high accuracy position measurement for the defects of operation principle. To solve the problem of measuring position accurately at high speed, a novel position measurement method based on inductosyns was given, which makes use of amplitude fine division means. The inductosyn’s output signal is an amplitude modulation signal and its amplitude is small. To use the amplitude fine division method, the inductosyn’s output signal should be amplified with no distortion. After showing the operation principle, a block diagram of the position measurement system was given. Experiment and simulation of function circuits was performed. The results prove that this method cancels the effect of the dynamic variables in the inducting signals out of inductosyns on position measurement, overcomes the shortage of current methods which can only measure position with low accuracy and low speed, can measure position with high accuracy, equal time interval in high speed moving conditions, etc.
XML functional dependency on NXD
Gao Qingyi, Lu Peng
2005, 31(04): 451-454.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 802
Abstract:
As semi-structured data, XML brings some problems in the normalization of Native XML Database data schema. To solve the problems, the method of combination of xml structure information and xml data information was proposed, and by using this method the concept xml functional dependency was defined. The concept of xml schema path, xml tree node path and the formalization of a validated xml document were studied. On the basis of these concepts, the definition of tree tuple and equation of tree tuple were constructed. As a result, the definition of xml functional dependency was proposed on the basis of above-mentioned concepts. The inference rules about xml functional dependency includes reflectivity, augmentation and transitivity were proved to deduce the implication of xml functional dependency in a given sets. The rules were proved right. Our work provides some theory basis of the normalization of native XML database data schema, and also enhances the semantic of xml data.
Problems in earth’s equivalent radius method application
Pei Xu, Ma Dongli
2005, 31(04): 455-458.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1144
Abstract:
To ravel the application range and some noticeable problems of the earth’s equivalent radius method during using this model to simply calculate the atmospheric refraction of radio waves, the mapping relationships of the variables between the earth’s equivalent radius model and the original earth model were derived from the definition of the earth’s equivalent radius method. The calculation results show that the height, elevation and range of ray is equal in the two models, geocentric angle keeps a rate about 3/4 in the equivalent procedure. The height, elevation and range of a radar ray in the earth’s equivalent radius model can be directly used to replace the relevant parameters in the original earth model. The Geocentric angle should be avoided as possible. Two samples were given to discuss the cases when the geocentric angle must be used, as well as the results and error analyses.
Simulated test technique for engine air intake and exhaust in high speed wind tunnel
Hao Weidong, Deng Xueying, Qu Fangliang
2005, 31(04): 459-463.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 1154
Abstract:
To study this test technique, the engine simulator(turbine powered simulator, ejectors)and the simulated parameters were analyzed and compared firstly in this paper. The Calculating methods of the ejector were presented using the theoretical base of One-dimensional ideal flow. An engine air intake and exhaust simulation experiment of a cruise missile with the ejector(the maximum diameter of the ejector is 41mm) was conducted in the FL-7 transonic wind tunnel.The test results showed that the free stream Mach number and nozzle pressure ratio getting 100% simulated, the flux coefficient realizing 89% simulated. The air intake and exhaust can increase the value of lift and drag, simultaneously the value of pitching moment was decreased, the value of base drag of the model is negative in no matter which situation whether existing air intake and exhaust or not.
Study on second-order sliding mode control law for affine nonlinear system
Yang Liman, Li Yunhua, Yuan Haibin
2005, 31(04): 464-467.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 921
Abstract:
The chattering and robustness issues of the existing sliding mode control especially second-order sliding mode (SOSM) control algorithms were analyzed. Aiming at the problems of slower convergence and stronger chattering in the nearly time-optimal SOSM control law, an improved control method was developed for the affine nonlinear systems through redesigning restrictive conditions and modifying reaching acceleration of sliding mode, which can effectively enhance responding speed of second-order sliding mode, as well as reduce the frequency and amplitude of chattering without losing the robustness of system. Taking a pendulum model as example, the simulation studies on the proposed algorithm were carried out, simultaneously comparing with the first-order exponential reaching law and the Lyapunov function-based SOSM control law. The simulative results demonstrate that the improved nearly time-optimal SOSM control law is appropriate for the uncertain nonlinear systems, and has the relative advantages on the aspects of chattering reduction and rapid response.
Network service performance measurement architecture
Xia Chunhe, Zhu Jianpeng, Pan Honglian, Zhang Cong
2005, 31(04): 468-471.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 867
Abstract:
Establishing network measurement infrastructure is a key problem in network measurement area. Under the environment of internet, sometimes network service providers and network administrators want to know the quality of their service from the perspective of users, and the users also want to learn which provider would be the best one. A distributed network service performance measurement architecture(SPMA) was put forward to solve this problem. Experience and shortcomings of current network measurement infrastructures were described and analyzed.Then the architecture and main features of SPMA were presented. SPMA makes use of a customized and extensible model for communication and data expression and deploys measurement probes automatically based on agent technique.SPMA provides measurement service for the outward users in the mode of web service.When a user requires SPMA to measure a service,SPMA will collect the performance information,which is provided by the probes distributed in different network area,and then the analysis results will be fed back to the user.
Application of orthopaedic robotics
Hu Lei, Gao Yifei, Wang Tianmiao, Wang Manyi
2005, 31(04): 472-476.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 820
Abstract:
From the aspect of the application in clinical surgery, the orthopaedic robotics and the robot assisted orthopaedic surgery system were discussed. Considering the clinical characteristics of the orthopaedic surgery and the functionality of orthopaedic robot system in clinical surgery, the orthopaedic robot system was divided into 5 parts: computer control subsystem, mechanical base, sensors and the corresponding signals processing unit, machine vision subsystem, and operation subsystem. Based on explanations of these 5 parts, the performance and application features of each part in clinical surgery were analyzed. The safety strategy of orthopaedic robot system in operation room was emphasized from the aspect of the design of the mechanical noumenon, the dimensional arrangement of the robot system, the structure of the control system, and the operation mode. In conclusion, the research focus and application trend of the system were investigated which can be as references for the design of the orthopaedic robot systems.
Numerical investigation of supersonic jet interactions for tactical bodies
Deng Youqi, Yan Chao, Wu Xiaojun, Zheng Ming
2005, 31(04): 477-480.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 998
Abstract:
In order to investigation of the jet interaction for finned bodies, the interaction between a lateral jet and the supersonic external flow was investigated numerically by solving the N-S equation. To model more exactly the nozzle geometry and resolve the complex flow associated with the lateral jet problem,the multi-block point matched grid generation technique and "O" type grid technique were applied. The detailed numerical simulation for a variety of missile geometries in the supersonic flow was performed. These include nonfinned axisymmetrical bodies and finned bodies with either strakes or aft-mounted tail fins. The computations were performed at Mach numbers 2 and 4.5. The computational results show significant interactions of the jet induced flowfield with the fin surfaces that produce additional effects compared with the body alone. The computational results were compared with the experimental results from a previously published wind-tunnel study that consisted primarily of global force and moment measurements. The numerical calculations show good agreement with the experimental investigation at supersonic Mach numbers.
Algorithm for color image coding based on wavelet zerotree
Yao Yuan, Zhang Xiaolin, Liu Rongke, Zhao Ling
2005, 31(04): 481-484.
Abstract References Relative Articles Resource File Access Statistics iconViews $!{v.htmlCount} iconDownload 814
Abstract:
To improve the coding speed of set partitioning in hierarchical trees (SPIHT) algorithm, the structure of SPIHT was re-designed, a simple listless coding algorithm based on wavelet zerotree was developed. Pipeline coding structure was realized by pre-processing and main-processing processes and access frequency was reduced. Pre-processing was designed to mark the significance of all nodes and main-processing to finish listless zerotree coding. In color image coding, the transform from RGB(red-green-blue) space to YUV (luminance-chrominance) space was performed, YUV color planes was correspondingly coded on bit plane sorting. So, the output coding stream was fully embedded. Generally, the first significant bit plane of luminance component is higher than chrominance component's. The performance of color image coding is further improved by output-controlled policy of chrominance component. Hardware implementation results show that the speed of codec is improved significantly, but rate-distortion performance is not reduced. The new algorithm is especially suitable for high resolution or irregular image codec chip design.

Copyright © Journal of Beijing University of Aeronautics and Astronautics

Address: Editorial Department of Journal of Beijing University of Aeronautics and Astronautics, 37 Xueyuan Road, Haidian District, Beijing Post Code: 100191 Email: jbuaa@buaa.edu.cn

Supported by: Beijing Renhe Information Technology Co., Ltd.