Abstract:To reduce the stability conservativeness for T-S fuzzy systems with time-delay and improve fuzzy controller design flexibility, the issues of delay-dependent stability analysis and controller design for T-S fuzzy time-delay systems under imperfect premise matching are investigated in this paper. A new less conservative delay-dependent stability condition is firstly proposed by constructing a novel augmented Lyapunov function, which contains a triple-integral term. Under the imperfect premise matching, our approach can enhance the design flexibility. Especially, some issues related to the fuzzy models with uncertain grades of membership can also be resolved. Finally, two numerical examples are presented to illustrate the effectiveness of the proposed methods. 

Abstract:To deal with non-linear, non-Gaussian state estimation problem, a kind of particle filter algorithm based on interval estimation was proposed. This paper analyzed the auxiliary particle filter at first. After interval estimating the expectation of the system states, the new algorithm sampled uniformly in the interval and updated the filter results using the new measurement. The interval extension conditions were proposed to ensure the validity of the estimated range and computational efficiency of the algorithm. Sampling uniformly in the interval avoids the particle degeneracy and improves the particle divergence. The experimental results show that the new particle filter is significantly better than the general particle filter. 

Abstract:To fully exploit discontinuous spectra, this paper adopts MCPC (Multi-carrier Phased-coded) signal structure to design discontinuous spectra waveform. The signal adopts cycle complementary P4 coded, the echo expression of the random discontinuous spectra MCPC signal is deduced, and the signal performance in different SNR, Doppler is analyzed. Based on the fast Fourier transform, we propose the processing algorithm flow of discontinuous spectra MCPC signal. The algorithm does the velocity processing, unifies the velocity information under different carrier frequencies, and then by IFFT coherent synthesizes different frequencies range information. For the higher PSL problem generated by discontinuous spectra, we design objective function, use CVX toolbox to solve the least square filter coefficients, and then restrain sidelobes level that coherent processing generating. 

Abstract:For utilizing compensation-flywheel to suppress angular momentum disturbance of rotary part on satellite, the principle of compensation is analyzed, and based on this, a double closed loop controller is proposed to be easily realized in engineering application. It uses velocity and the velocity integral signal of encoder for high-authority control (HAC)/low-authority control (LAC). The problems in current applied compensation-flywheels and the corrective methods are presented. The guideline to determinate parameters of compensation-flywheel is introduced which is based on the motion characteristic of payload and requirement of satellite attitude control. In the section of simulation, result of residual angular momentum in every movement mode is demonstrated, and it reveals that the proposed system could compensate 97% disturbance. The control strategy has a satisfied performance to increase the response speed and reduce the steady-state error. 

Abstract:To solve the problem of Acrobot that an underactuated robot relying on excitation combined with other control methods can not achieve complete the action of catching the target rod, we firstly propose concept of research of big damping nonholonomic constraint in underactuated robot and control strategy of stably grasping target rod, design the gripper dedicated to this kind of robot, which can grasp the rod constitutes a big damping nonholonomic constraint state, and propose the control strategy of using rapidly swing up combined with turn back feedback control for the underactuated robot stable grasping rod motion. The corresponding controller is designed, and the robot simulation model is established using ADAMS and MATLAB software. The simulation achieves reliable grasping rod motion control of the robot, and the experimental results verify the driving ability of each joint of the robot and the effectiveness of the proposed control strategy.

Abstract:To guarantee the design quality and improve the design efficiency of mechanical products, taking arc water chamber of steam turbine condenser as example, the paper researches the key technologies in the development process of parametric design system, which can generate both 3D models and associated 2D drawings automatically. Adopting database as the interface of UG and AutoCAD, 2D/3D bidirectional associated relationship is established across platforms. A nonpermanent record is set within the database to save parameters temporarily. Dynamic storage and invocation of parts information is realized by introducing linked-list data structure. Automatic assembly method based on named datum is proposed. Development process and insertion algorithm of modularized geometric figure are also presented. The experimental result shows that this parameter-driven software is a successful application of computer-aided design.

Abstract:This paper studied the deformation behavior of Polycarbonate (PC) sheet at temperature of -50,-20, 0,0, 60 ℃ and strain rate of 0.6,0.6,0.6,0.12 s-1, respectively. Based on tensile tests and parameter identification, a modified DSGZ constitution model was developed to describe PC mechanical properties at the temperature from -50 ℃ to 60 ℃, and the results show that the model can give much better description of PC mechanical deformation at low and medium temperature.

Abstract:Conventional kNN algorithms ignore label correlations when being applied to multi-label text categorization. To cover this shortage, an improved Multi-label kNN approach for text categorization is proposed. A specific distance metric based on KL divergence is derived to measure the similarity between individual documents. Based on statistical information gained from the label sets of neighboring documents, a fuzzy maximum a posteriori principle is utilized to conjecture the label sets of the unlabeled documents. Different from ML-kNN, the proposed approach can exploit label correlations to improve classification performance effectively. Experiments on three benchmark datasets using 5 popular multi-label evaluation metrics suggest that the proposed approach achieves superior performance to some well-established multi-label learning algorithms, such as ML-kNN、Rank-SVM and BoosTexter.

Abstract:Thermodynamic properties in a fluidized bed nuclear reactor were simulated by means of two-fluid model coupled heat conduction model. Neutron transport equation was used based on group diffusion method. The effect of velocity of inlet coolant and different packing height on the temperature distribution was studied. Results showed that the gas temperature was uniform in a fluidized bed nuclear reactor. The temperature fluctuation strengthened with the velocity of inlet coolant in the annular and center zones, and the gas temperature was raised with the increase of packing height. The simulation result of instantaneous gas temperature was in an agreement with the calculation results of Pain et al.

Abstract:To improve the efficiency and accuracy of numerical simulation of single-phase flow and heat transfer in Pressurized Water Reactor (PWR) rod bundle, simulations were performed in two computational models of four-subchannel without spacer and 5×5 rod bundle with a mixing vane spacer under different working conditions. The different turbulence models, near-wall treatments and near-wall mesh generation strategies were comprehensively evaluated from two aspects of heat transfer (Nusselt number) and fluid flow (Secondary flow, turbulence intensity) by using high quality wall-function mesh and low-Reynolds-number mesh. Analysis shows that the numerical results of Nusselt number were seriously affected by both of the turbulence model and near-wall treatment, while secondary flow and turbulence intensity were mainly influenced by turbulence model. The Reynolds Stress Model (RSM) could predict the secondary flow field in bare rod bundle better than eddy viscosity models, and there was no significant difference for calculating the secondary flow field downstream of the mixing vane spacer grid. Among all turbulence models, only the SST k-ω model behaved well even combined with different type of near-wall meshes. Using the SST model with wall-function mesh for engineering computation can provide both the efficiency and accuracy of simulation, and the SST model combined with low-Reynolds-number mesh is recommended for numerical research.

Abstract:To accurately calculate the herringbone gear tooth root dynamic stress, nonlinear herringbone gear vibration model of twelve degrees of freedom is established considering transmission error, meshing stiffness, corner mesh impact, and backlash. New method for calculating tooth root dynamic stress is put forward considering the influence of real-time dynamic load on the load distribution coefficient. Taking a ship herringbone gear transmission system as an example, the results consistently indicate that herringbone gear tooth root dynamic stresses both increase with the increasing of load torque and driving wheel rotational speed. With the external load increases, the relative fluctuations of the dynamic stress in meshing tooth root decreases first and then increases due to the influence of teeth backlash. Numerical simulation and experimental data are in good agreement. The method can more accurately reflect the trends of tooth root stress fluctuations.

Abstract:Taking full advantage of the time-domain-sparsity of wireless channel, orthogonal frequency division multiplexing (OFDM) sparse channel estimation based on compressive sensing (CS) reconstructs accurate channel information using few pilots. By improving the CS measurement matrix and using judgment of noise estimation, a novel CS channel estimation algorithm opposes the non-integral delay multipath existed in actual OFDM systems and this algorithm effectively combats the energy leakage caused by non-integral delay multipath. Simulations show that the novel algorithm has better performance than the original CS channel estimation algorithm, and it resists the non-integral delay multipath in OFDM digital transmission systems more effectively.

Abstract:The frictional moments are calculated respectively based on the Hertzian contact theory and the method of effective ball considering elastic hysteresis of material, spinning sliding of roller and viscosity of lubricating oil, and the influences of contact angle, helix angle and tooth number of roller thread on frictional moment are analyzed. Furthermore, a calculating model of transmission efficiency for planetary roller screw is developed and the relationships of between the screw rotational speed, structure parameters mentioned above and transmission efficiency are discussed. The results show that the frictional moment is principally generated by roller's spinning sliding. Increasing the rotational speed of screw leads to decreasing of the transmission efficiency and a higher axial load can increase the transmission efficiency at the same rotational speed of screw. A higher contact angle can decrease the frictional moment and increase the transmission efficiency. The helix angle has less influence on frictional moment and can improve the transmission efficiency. Besides, it is helpful to enhance the carrying capacity and reduce the total frictional moment by increasing the tooth number of the roller thread.

Abstract:To solve the problem of prediction of multi-axial fatigue life, a new thought and method of establishing multi-axial fatigue life model is proposed. The multi-axial fatigue life model is established by fitting and optimizing axial and multi-axial test data both. This method reduces the restrictions of the formation of multi-axial fatigue damage parameters and the type of multi-axial fatigue test data. On this basis, a new multi-axial fatigue damage parameter based on maximum shear strain amplitude and normal strain and stress on the plane of maximum shear strain amplitude is proposed. The establishing method of multi-axial fatigue life model is evaluated by the multi-axial fatigue test data of ZTC4 cast titanium alloy, pure titanium and BT9 titanium alloy. The result shows that the new method is feasible. The prediction ability of the establishing life model is almost within a factor of two scatter band.

Abstract:Considering the effect of installation error, bending deflection and torsional deformation on load distribution, as well as drive feature of the gears, an approach based on the load sharing of modified double helical gears with the pinion axial float was proposed in which the modified tooth surfaces were represented by a sum of two vector functions that determine the theoretical tooth surface and the deviations surface fitted by 3 B-spline based on tooth surface mesh data from the longitudinal curves, and a TCA model including axial displacement and LTCA model was built. Besides, axial move process showed that the left and right tooth surface bore the same torques, so the modification was thought as a helical gear modification, and only one side tooth was considered and the other side was the same. In addition, minimum load density was used to evaluate load sharing, and genetic algorithm was used to optimize the parameter of curve. The results show that the axial motion process is about the tooth gap mutual compensation process which makes both of the tooth load distribution same and uniform, in short, when considering modification and axial motion, the loads tend to be uniform totally.

Abstract:To solve the problem of aware relationship-balance subgroup of context-acquisition of social computing, on the basis of the relationship-balance, and according to the characteristics of the 2-mode network environment, the relationship-balance gather subgroup and context entity of b alance gather coefficient is put forward and used for group behavior analysis. The balance gather of threshold method is used to transform iterative optimization problem in the computing process and put forward the CABS-2mode algorithm used in the group clustering. The CABC-2mode algorithm is used in the acquisition of balance gather coefficient. Balance experiments show that by using the algorithm based on relationship-balance subgroup and the time-context and social-context fusion parameters, the aware relationship-balance of the entity in the context value is accessed, and the subgroup of balance to the intensity fluctuation process and the entity of behavior process are analyzed.

Abstract:The problems of privacy preserving, trajectory data simplification and online processing attract considerable efforts from researchers in the area of trajectory data mining, unfortunately, it is difficult for traditional method to solve all these problems. This paper proposes an online similar trajectories mining method which can preserve the privacy of original trajectory data. The method first compressed and perturbed the original data based on random projection technique, then found the similar moving objects in each time segment by clustering the transformed data based on density, and finally it found similar trajectories by estimating that if the trajectories were similar for a long enough duration and estimated the similarity of trajectories using local sensitivity hashing. This avoided the intersection operation in traditional method and reduced the computation time. The experimental results show that this method can find similar trajectories effectively and reduce the cost of computation time. 

Abstract:To scientifically predict energy demand, the economic development level, population scale, urbanization rate, industrial structure and level of technical progress were selected as the influencing factors of energy demand, the weight of each model based on Deviation Maximization Method was calculated, and the combined model of ARIMA, Multiple Regression, Grey GM(1,1) and Support Vector Regression were established to calculate energy demand from 2005 to 2011 respectively. The result shows that the combined model based on deviation maximization method has higher prediction accuracy.Finally predict China energy demand from 2012 to 2020 based on the combined model, the prediction results show that China energy demand increases at an average growth rate of 3.42% from 2012 to 2020, China energy demand in 2020 will be about 30% more than that in 2012. 

Abstract:Polyp detection in CT Colongraphy suffers from imbalanced data sets where negative samples (non-polyp) are dominant. In data level, SMOTE (Synthetic Minority Over-Sampling Technique) was applied to alleviate imbalanced degree by synthetic minority samples. In algorithm level, Boosting approach was employed in order to improve classification performance. Having combined Boosting with SMOTE (SMOTEBoost), the proposed classifier not only improved the prediction of the minority samples, but also guaranteed the accuracy over the entire data set. To satisfy real-time requirements for polyp detection, MRMR (Minimum Redundancy Maximum Relevance) was provided to select low-cost simple features for training the first stage of cascade, resulting in refusing the great majority negative samples and speeding procession. The experimental results showed that the classifier could achieve an overall per-polyp sensitivity of 90％ (corresponding to the polyp whose diameter is equal to or greater than 5 mm), with false positives of 6 per volume on average.

Abstract:To take full use of context information to learn the spatial relationship of the image, a novel model based on Generative Model and Region Connection Calculus (RCC) is proposed in this paper. We name it GM-RCC model, which is used for SAR image classification. Firstly, a SAR image is over-segmented into multi-scale super pixels via adopting the image pyramid. Then the hierarchical RCC model is utilized to describe the spatial relationships among these super pixels. All hierarchical RCC relationships are learned and reasoned under the Generative Model reasoning framework. The experiments are carried out on SAR image datasets and polarimetric features are selected with other typical features. The results reveal the efficient performances and superiorities of the proposed algorithm.

Abstract:The local minimum problem of SPDS algorithm—the training algorithm of BP neural network, is studied. As one of SPDS algorithm features based on the single parameter dynamic searching algorithm is that the variables are searched one by one, this paper proves that the equivalence error function of each iteration is a quasi-convex function, and minimum points are presence and can be found out. The initial value set from which the iterative must be convergence is defined as the global minimum area, and according to the local minimum problems, L-SPDS algorithm is given. The global minimum area of the SPDS algorithm expanding along coordinate direction is the global minimum area of L-SPDS algorithm. The possibility that SPDS algorithm converges to the global minimum point greatly increases, which is proved by algorithm simulation test.