Abstract:The problem of trajectory tracking of a two-link free-floating flexible space robot is concerned in this paper. The dynamic equations of the robot are firstly developed by using Lagrange s principle with elastic vi- bration, and then they are transformed into a fully controllable form with the flexible vibration disturbance for the purpose of controller synthesis. By this simplified model, a robust control approach using adaptive non-sin- gular terminal sliding mode is developed, in which the dynamic uncertainty and disturbance can be eliminated via the online updating law, and the associated Lyapunov stability analysis are also investigated. Numerical simulation results show that the sliding mode is modified by adding a conditional integral to reduce the stable error in the present of attitude disturbance of a spacecraft

Abstract:A controller is designed for anti-lock braking system ( ABS) with discontinuous characteristics of on/ off valves. Firstly, the dynamic characteristics under Increase, Hold and Decrease modes are discussed, and a math description is given for ABS with on/off valves, including wheel slip continuous dynamics and actuator dis- continuous dynamics. Considering the requirement on applicability and robustness, an approach for nonlinear controller design is proposed which uses system state as switching law to guarantee the stability. The idea is to develop two switching surfaces using Lyapunov method in the sense of Filippov, and the state space partition is regarded as the switching law, with the stability ensured via switching surfaces selection. Further, to avoid fre- quent switches, the control objective is modified to the convergence of an equilibrium set, and the influence of the size about the equilibrium set on the closed-loop system performance is discussed. Simulation and experiment tests illustrate that both high braking efficiency and ride quality are obtained with few control parameters. Key words: anti-lock braking system; on/off valve; wheel slip; switching surface

Abstract:The dynamics of the water-entry cavity created by vertical water entry of cylinder with 1500 cone nose is simulated based on the Reynolds-Averaged-Navier-Stokes ( RANS) equations, in which the Finite-Vol- ume Method is used in the discretization of the control equations, and the Volume of Fluid Method with the sources of mass transfer due to the natural cavitation is adopted for the multiphase flows of water-entry cavity. The dynamic mesh method is used to control the constant speed of the cylinder. The results show that the non- dimensional time of cavity closure is a function of the atmospheric pressure and the atmospheric density. The cavity closure types depend on the atmospheric pressure and the water-entry velocity greatly. The non-dimen- sional diameter of the cavity created by the cylinder with cone nose at the time of closure is a function of the atmospheric pressure

Abstract:Based on the difference in time scale between the aerodynamic fins and reaction jets, the singular perturbation analysis is employed to split the dual control system of the interceptor into slow and fast subsys- tems. Then, the robust Raytheon four-loop topology and linear quadratic regulator are used to design the fin control law and the reaction jet switching surface. Finally, the proposed autopilot is used to follow a steady- state acceleration command. It is shown that not only the acceleration command can be followed steadily but also the control effort can be distributed among the actuators effectively. The response in the first phase is im- proved when the initial value of RCS is large and the RCS trends to zero when the system is steady. Simultane- ously, the aerodynamic surfaces are used to trim the airframe

Abstract:The multiphase flow characteristics and hydrodynamic evolution during the rise of underwater vehicle in the vertical launch tube have been researched with numerical simulation method. The multiphase mixture model, Singhal cavitation model and a standard k-8 turbulence model with a dynamic mesh technique were adopted to solve RANS equation in conjunction. The fluid-solid coupling problem of moving boundary of missile body and multiphase flow field was solved and the axial symmetric gravity flow field and hydrodynamic character- istics of underwater vehicle were derived by using the numerical simulation. The results show that the gaseous fluid affects on trajectory of underwater vehicle and hydrodynamic load. The volatility reason of different pressure coefficient and viscous force coefficient and toll force coefficient were derived by analyzing simulation results

Abstract:Employing the single-gimbal control moment gyroscope( SGCMG) as the main actuator, this paper deals with the rapid maneuver problem of flexible satellite. Firstly, a rigid-flexible coupled dynamics model with variable parameters and model uncertainties is established for the flexible satellite, and the mixed actuator consisting of CMG and RW is configured for agile satellite to meet the requirements of rapid maneuver ability and high precision. Then, a variable structure control law of the integral type is designed with a neural net- work to estimate the uncertainties and eliminate their effects on the system. Finally, the proposed algorithm is validated by simulation. Simulation results show that under external disturbances and model uncertainties, the designed system could suppress vibrations of flexible appendages and achieve the pointing accuracy and high stable accuracy required rapidly without encountering singularities of the actuator

Abstract:According to the features that uplink CQI feedback is high and not fair enough in OFDMA system, the reducing feedback resource allocation algorithm is proposed. Users in the cell center with higher SNR do not need feedback CQI, and users in the cell edge with lower SNR adopt l B feedback when the load is low while the Best-M is adopted and the load is heavy. Meanwhile, according to the Best-M project, the first user preference is proposed. On the premise of ensuring the necessary feedback information of resource allocation, the proposed algorithm trades off between complexity and performance, and meets the users' fairness

Abstract:To utilize the multiuser diversity efficiently in multiuser MIMO systems, opportunistic scheduling is employed, where the user with largest SNR is adaptively selected according to channel state information feed- back from the receive side and in the meantime, and to utilize the multiplexing gain effectively and improve the capacity, a novel scheme of MIMO systems combining opportunistic scheduling and spatial multiplexing with zero-forcing receiver is presented under Rayleigh channel. Using the direct method based on polynomial expansion, the expressions of error rate with M-QAM and M-PSK modulations, the diversity gain and the sum- rate capacity under different channel conditions are got, respectively, and the asymptotic forms are derived based on Taylor series. The correctness of theoretical analysis is verified by the corresponding Monta-Carlo simulation results which indicate that the scheme with multiuser diversity provides much larger diversity and higher capacity than that without opportunistic scheduling

Abstract:A tendon-driven finger structure is applied to optimize the mechanism, reduce the complexity and improve the reliability of prosthetic hand, which also realizes the independent movement for single finger. The structure consists of a drive tendon, three knuckles, three joints, torsion springs, and so on. The joint torsion spring is designed to realize the joint preload and the joint reversion after the tendon looseness. By optimizing the spring stiffness, it is able to realize the sequential curling and the large range grip. Based on these analy- ses, the relation between contact force on the knuckles and the drive torque of the wire wheel, the finger dy- namic model and dynamic equations are established. The numerical calculation, simulation and experiments are done to validate the correctness of the theoretical analysis and the feasibility of the finger structure. By the advantages of fewer parts, simpler structure and higher reliability, the tendon-driven finger structure provides favorable conditions for development of multi-degree prosthetic hand

Abstract:To improve the classification performance of cold rolling steel surface defect, a 3D reconstruction algorithm of surface defect is proposed based on shape from shading theory. A modified Oren-Nayar diffuse re- flection model is presented according to the design of optical path for surface defect detection system, then cor- responding reflection map equation is deduced with perspective projection model. The equation is solved by fast sweeping method based on high-order Lax-Friedrichs Hamilton function and Newton iteration, and finally the extraction of surface defect 3D information is realized. The 3D reconstruction experiments with synthetic image and surface defect image are carried out, and the results show that the reconstruction precision is high, the accuracy of modified illumination model is confirmed. The 3D information of cold rolling steel surface de- fect could be extracted effectively by this algorithm, which is helpful for improving the classification perform- ance of surface defect

Abstract:Numerical method is used for solving rotor-seal nonlinear dynamics equation, so that the dynamics effects of whirl speed, pre-whirl, labyrinth seal gap, pressure are investigated, and the leakage effects of seal gap, pressure, labyrinth seal structure are researched. The numerical method is verified to be correct by ex- periments. The results show that reducing pre-whirl and increasing seal gap can reduce the cross-stiffness coef- ficients, and improve stability purposes. There is a critical value of tooth width l. 04 mm, the leakage seal in- creases with the increasing of tooth width when it is more than the critical value, and the leakage seal decrea- ses with the increasing of tooth width when it is less than the critical value. At the same whirl speed, the leak- age increases with the increase of labyrinth seal and pressure, and decreases with the decrease of cavity depth

Abstract:To improve the efficiency of triangle mesh surface reconstruction in neural network, an improved Kohonen neural network is put forward, which combines Kohonen neural network and faintness clustering algo- rithm, and by which large scale scattered point clouds triangle mesh surface and vase surface reconstruction have been done. Characteristics comparison is carried out between the improved algorithm and general one, and the results show that the improved algorithm avoids repeat circulation in general algorithm, reduces calcu- lation time, improves the efficiency and rate of the triangle mesh surface reconstruction. Simulation reconstruc- tion result indicates that the improved arithmetic can realize sparse and dense triangle mesh surface reconstruc- tion and data condensation under preconditions with primary data characteristics. The improved arithmetic has fast network convergence speed

Abstract:From the point of view on the network system availability, to evaluate the harm caused by security incidents, a performance - based quantification assessment method of network security is proposed. The meth- od references the concept of entropy in information theory to quantify the performance indexes by choosing router nodes, and compares these index changes in the entropy before and after the security incident to meas- ure the impact on the network. Worm simulation and actual provincial nodes experiment show that the pro- posed approach can be effectively applied to the quantification assessment of large-scale network availability

Abstract:Existed reliability researches of architectural styles are mainly aimed at individual architectural style. To study system reliability of multiple architectural styles during software deployment stage, the system of integrated architectural style and reliabilities of software components are modeled by the connector method. Experiments show that with the increasing of system run time, the system reliability of the integrated architec- tural style and component reliabilities mainly depend on the number and time of software components which are in the executed state. On the basis of system reliability analysis of the integrated architectural style and relia- bilities of software components, the reasonable time is decided by redeployment or replicating components to improve the system

Abstract:In this paper, a construction approach of confidence management software is presented to keep the confidence in the software lifecycle. The originality of the proposed approach is to combine software confidence theory and model driven development approaches to a consistent approach of Confidence Model Driven Archi- tecture and Methodology. The confidence verification problem of the management software is described clearly according to the existing research results. This approach focuses on the structure elements of the layers in ICEMDA, describes the confident model, measures confidence index, verifies and optimizes the confidence of the element. The maintenance and transformation of the confidence among the layers is based on the model se- mantic maintenance technology of ICEMDA. The confidence verification of the business component platform - specific model is taken as an example to introduce the implementation mechanism of this approach

Abstract:For evaluating elastogram objectively, image processing and pattern recogniton techniques are pro- posed. First the real elasticity information encoded in color was extracted by transform the image from RGB color space to HSV space. Then the statistical features and texture features were extracted from region of inter- est on the elastogram. The important and reliable features were selected by using Minimum-Redundancy-Maxi- mum-Relevance ( mRMR) algorithm. Finally the selected features were input to the SVM classifier to classify the thyroid nodules into benign and malignant. The experiment results confirmed the method had higher accu- racy (92% ). It is helpful to improve the clinical accuracy by using CAD techniques

Abstract:According to the synchronous acquirement of multi-, hyper-spectral remote sensed imagery, a Gray Level Difference Associated Possibility matrix ( GLDAP) method is proposed in the paper to analyze visual differences between multi-band data. The matrix is built on two bands of image that are selected in light of land-cover spectrum characteristics. Thereafter, the co-varying statistics of gray level in each image is recor- ded and quasi-3-dimention texture features are extracted based on GLDAP. During experiments, GLDAP is employed in classifications and annotations of land cover types, compared with GLCM method. The results re- veal that the GLDAP has better performances than GLCM. Moreover, it could overcome the limitation of single band processing and understanding, on which GLCM based, and to a certain degree, decrease misrecognition rate caused by worse visual discrimination of land types at data level. The two methods have same time com- plexity; hence, GLDAP may be accepted as another choice in getting excellent precision and better perform- ance under the same time consuming

Abstract:To improve the capacity of AlISB4033w/Al at room temperature, bismuth with a low melting point was introduced into the interface of the composite by in situ reaction. The influence of the coating contents on the tensile properties and damping capacities of the coated composites at room temperature were investigated. The results indicated that the tensile properties of the coated composites decrease and the damping capacity in- creased with the increasing of coating contents, while the damping value of the coated composites strongly de- pend on not only the coating contents, but the strain amplitude. A damping peak in the coating composites at low strain amplitude ( about 4 x 10_-4) was observed, which attributed to dislocation mechanism. When the strain amplitude exceeded 6 x 10_-4, the damping was caused by the interfacial micro-slip

Abstract:To solve the problem of frequency spectrum, a method using all-phase FFT is presented in this pa- per. Based on the theory of all-phase FFT and OFDM, the mathematical expression, model and algorithm of modulation and demodulation in all-phase OFDM system were derived. The all-Phase FFT can adjudicate the phase and amplitude by using the function of spectrum analysis. The simulation results show that All-Phase OFDM system has less phase error, spectrum leakage and lower BER than OFDM

Abstract:To obtain high quality finite difference mesh for castings with complex geometric shapes and thin walls, and to establish an effective algorithm for finite difference mesh generation of STL solid models, an en- meshment process of multiple STL models based on slice line scanning method was described and a computer program for finite difference mesh generation was developed. The program adopted dynamic data structure, up- dated technique of treating singular points and mesh filtering method for fault tolerance. It can be applied to generate 3D non-uniform meshes for assembled STL solid models rapidly. The algorithm is fast in running, al- terable in mesh spacing, optimizational in singular points treating, and high fault tolerance. The mesh genera- tion is rapid, easy to use, low memory needed, accurate and reliable

Abstract:Aiming at the problem that viewpoint selection are widely used in many applications, such as, 3D object visual shape analysis and processing, graphics drawing, scene rendering and optimal layout, we define a new skeleton map with the vertex importance based on curve-skeleton of 3D object and present a computation method for the information of viewpoint. Based on Loop subdivision stencil, the final best viewpoint and worst viewpoint can be rapidly achieved under a certain threshold using iterative subdivision for the triangular mesh generating from the selected initial viewpoints. Both analytical and experimental results show that the new skel- eton map can effectively integrate into viewpoint selection and provide the functionality of rapid selection for the final best and worst viewpoints. The run time efficiency and maximum visual topological perception infor- mation is also demonstrated by these experiments and result analysis

Abstract:To analyze the direct and indirect effectiveness of added value increasing resulted from factors of production in Chinese construction industry, the composition of factors of production in construction industry were analyzed, and a path analysis model was constructed. The data are from relevant statistics from 1996 to 2007. The results are as follows: Firstly, the increasing of added value in construction industry is mainly from quality improvement of employees and effective uses of current assets. Meanwhile, the amount of labor input and effective uses of fixed assets are the main two factors which have indirect effectiveness on increasing of added value in construction industry

Abstract:To optimize the urban living environment,this paper presents an urban living environment evalua- tion model based on the method of principal component analysis. Taking Harbin for example, the living envi- ronment in Harbin from 1995 t0 2009 is studied, and the results show that from 1995 t0 2009, affected by the main components of the level of the green and education, social security, health service and food supply, the living environment has gone through two stages, namely the stage of improving significantly (1995-2003) and the stage of enveloping stably ( 2003-2009 ) . Finally, some appropriate suggestions for the improvement of liv- ing environment in Harbin are put forward

Abstract:To establish the dynamic models of knowledge movement and evolution under time dimension, the phenomenon was understood as the basic element to constitute knowledge in this study, where the concept, in- tuition ( time-state) and relevance logic were taken as the basic categories of phenomenon composition, and meanwhile the granular structure was taken as the basic structure of phenomenon formalized representation. Based on the isomorphism between formal concept analysis and rough set theory, the granular structure models were established in concept and intuition category of phenomenon, and the correlation and relevance logic were given among formalized phenomena. Based on the formalized representation of phenomenon, the knowledge representation model can be established more completely than conceptual model in semantic description.

Abstract:The current corpora of question classification are relatively small and difficult to meet the practical needs of Question Answering system, so that we use active learning methods to construct a Chinese question classification dataset and for question labeling. In addition, we improve the performance of labeling with fea- ture selection. Experimental results show that by using active learning we can quickly converge at the best ac- curacy (85% ) and by using manual tagging we can have small feature set size. The active learning-based la- beling method achieved very good classification performance with less manual annotation tagging, which can significantly improve the accuracy of classification to some degree

Abstract:The design of high precision quartz vibrating beam accelerometer needs the key part quartz resona- tor has good dynamic performance. An implicit objective function of optimization design is built up based on the theory of modal analysis and finite element analysis, and the descriptions for structure optimization design and the rules for building structure optimization design model are summarized. The detailed steps for genera- ting analysis files, defining optimization variables, setting and optimizing are given. The result of design is reasonable and the scale factor of optimized pendulum is improved by 16%

Abstract:To obtain the effects of notch type on the flow field and dynamic response characteristic of the pilot operated directional valve, the simulations of steady and transient flow with three kinds of notch based on CFD and Matlab Simulink software are carried out, and the discharge coefficients, the efflux angles into the notch and the axial forces on the spool are obtained. Two-phase Mixture flow model and standard K-epsilon model are used in the flow field simulation. The results show that the smaller the notch opening and the larger the flow rate, the greater the transient axial forces and the possibility of cavitations. When the moving speed of the spool increases, the possibility of cavitations increases during the notch open process, and decreases during the notch close process. There are no cavitations generated with the notch opening 2 mm when the flow rate is within 35 L/min. The direction of flow forces is to open the notch, and the flow forces calculated from Con- ventional Formula do not comply with the real ones. The results from dynamic analysis for the spool show that the spool with K or V notch responds quicker; the working speed of the system mainly depends on the dis- charge coefficient of the notch; and the spool displacement should be limited to avoid oscillation. In conclu- sion, the type of the notch impacts the flow field and dynamic response of a piloted directional valve a lot.

Abstract:Aiming at reducing the computational complexity greatly and achieving high detection performance in cooperative MIMO-based WSN, a new complexity reduction ML detection algorithm is proposed. Using con- ventional V-BLAST algorithm, the best performance layer is found, and the neighborhood is considered to be candidate set. Regard the every symbol in the candidate set as initial value, we adopt V-BLAST algorithm a- gain to detect the symbol of other layers. At last, we use the maximum likelihood criterion to judge the candi- date vector. Because the number of constellation point in the maximum likelihood detection algorithm is re- duced effectively, the complexity of the algorithm decrease greatly. The simulation results show that the pro- posed scheme obtains good comprehensive performance

Abstract:To reduce crew expenses and raise operation profits of flexible production enterprises, a mathemati- cal model was constructed on the basis of reasonable operator allocation scheme and optimal sequence of opera- tions, and a multi-objective mixed algorithm was used for solving the problem. The operation is divided into two layers, and the man-hour optimization scheme can be acquired by genetic algorithm and dynamic program- ming method. A simulated annealing genetic algorithm was proposed to optimize the sequence of operations, in which the search was limited to the space of permutation vectors of the order, and a given set of jobs were per- formed in the first stage using a hybrid crossover operators and mutation operators to redesign the selection op- erators. A set of test results show that the proposed algorithm is effective