Effective Discriminative Feature Selection with Non-trivial Solutions

Feature selection and feature transformation, the two main ways to reduce dimensionality, are often presented separately. In this paper, a feature selection method is proposed by combining the popular transformation based dimensionality reduction method Linear Discriminant Analysis (LDA) and sparsity regularization. We impose row sparsity on the transformation matrix of LDA through ${\ell}_{2,1}$-norm regularization to achieve feature selection, and the resultant formulation optimizes for selecting the most discriminative features and removing the redundant ones simultaneously. The formulation is extended to the ${\ell}_{2,p}$-norm regularized case: which is more likely to offer better sparsity when $0<p<1$. Thus the formulation is a better approximation to the feature selection problem. An efficient algorithm is developed to solve the ${\ell}_{2,p}$-norm based optimization problem and it is proved that the algorithm converges when $0<p\le 2$. Systematical experiments are conducted to understand the work of the proposed method. Promising experimental results on various types of real-world data sets demonstrate the effectiveness of our algorithm

Analysis Approach to Durability Based on Material Initial Fatigue Quality and S-N Curve

AbstractBased on probabilistic fracture mechanics approach, a new concept of material initial fatigue quality (MIFQ) is developed. Then, the relation between S-N curve and crack propagation curve is studied. From the study, a new durability analysis method is presented. In this method, S-N curve is used to determine crack growth rate under constant amplitude loading and evaluate the effects of different factors on durability and then the structural durability is analyzed. The tests and analyses indicate that this method has lower dependence on testing, and higher accuracy, reliability and generality and is convenient for application

Control energy of complex networks towards distinct mixture states

Controlling complex networked systems is a real-world puzzle that remains largely unsolved. Despite recent progress in understanding the structural characteristics of network control energy, target state and system dynamics have not been explored. We examine how varying the final state mixture affects the control energy of canonical and conformity-incorporated dynamical systems. We find that the control energy required to drive a network to an identical final state is lower than that required to arrive a non-identical final state. We also demonstrate that it is easier to achieve full control in a conformity-based dynamical network. Finally we determine the optimal control strategy in terms of the network hierarchical structure. Our work offers a realistic understanding of the control energy within the final state mixture and sheds light on controlling complex systems.This work was funded by The National Natural Science Foundation of China (Grant Nos. 61763013, 61703159, 61403421), The Natural Science Foundation of Jiangxi Province (No. 20171BAB212017), The Measurement and Control of Aircraft at Sea Laboratory (No. FOM2016OF010), and China Scholarship Council (201708360048). The Boston University Center for Polymer Studies is supported by NSF Grants PHY-1505000, CMMI-1125290, and CHE-1213217, and by DTRA Grant HDTRA1-14-1-0017. (61763013 - National Natural Science Foundation of China; 61703159 - National Natural Science Foundation of China; 61403421 - National Natural Science Foundation of China; 20171BAB212017 - Natural Science Foundation of Jiangxi Province; FOM2016OF010 - Measurement and Control of Aircraft at Sea Laboratory; 201708360048 - China Scholarship Council; PHY-1505000 - NSF; CMMI-1125290 - NSF; CHE-1213217 - NSF; HDTRA1-14-1-0017 - DTRA)Published versio

Dynamic analysis of ground steering response of aircraft with electric taxi system

To provide taxi capability without the use of engines or tractor, electric landing gear drive is considered as a potential system add-on. Driving torque and nose wheel steering angle controller are established which are verified by civil aircraft examples. Quasi-steady method is applied to calculate tire forces and moments. The ground steering response of aircraft is simulated, and then different taxi conditions including powered nose wheel mode and powered main wheel mode are compared. Two conclusions are obtained: Electric taxi system helps the aircraft turn on the spot and the turning radius is smaller than the aircraft using engines; differential powered main wheel mode has the minimum turning radius while turning-circle with uniform velocity, and it has smaller difference between two vertical loads of main landing gear than powered nose wheel mode

Analysis of axial stiffness characteristics of a mechanism of fluid bag shock absorber under alternative factors

A mechanism of fluid bag shock absorber which could provide axial shock protection under small displacement and small deformation was designed. The finite element model of the mechanism was established in ABAQUS, the different types of loads imposed on the bottom of mechanism when the mechanism worked in different environment were described and the load stiffness matrix was obtained when pressure loads were imposed on the mechanism. The effects of the notch in fluid bag on axial stiffness characteristics were discussed. The results indicate that the flip of inner shell occurs as the axial concentrated load is imposed to the bottom of inner shell and the notch in fluid bag has little effects on the increment of pressure and volume variation of bag. The equivalent axial force generated by pressure loads imposed on the inner shell was calculated, the axial displacement of inner shell as well as increment of bag pressure caused by pressure loads is larger than concentrated load. The effects of different factors affecting the axial stiffness characteristics were discussed. The factor of load type has almost no effects on the axial stiffness variation, and has small impact on the increment of pressure variation of bag; Outer shell appears to be one of the crucial factors affecting the axial stiffness and increment of bag pressure variations; Fluid bag is the key factor determining the axial stiffness characteristics of mechanism, both of the axial displacement of inner shell and increment of bag pressure increase with loads when the pressure loads are imposed on the surface of fluid bag

Research on touchdown performance of soft-landing system with flexible body

In the overall study of the design and performance of the lunar Lander, analysis of touchdown dynamics of the landing stage is an important part. In this paper, the influence of the lunar Lander’s body deformation on the landing performance is studied. First, the equations with the flexible part are derived from the subsystem method and deducing a multi-mass model by comparing and analyzing the mode of the body in Lander. Second, based on the existing aluminum honeycomb buffering and the model used in the landing-impact tests for the soft-landing system, a finite element model for the cantilever-type landing gear with four legs is established in MSC.Patran and submitted to MSC.Dytran to conduct a simulation analysis. Finally, the flexibility of lander’s body to the performance in landing is studied. Results show that the deformation of the body has considerable effect on the overloading of the lunar Lander system though the deforming can absorb litter energy during landing

Analysis of stiffness characteristics of a new fluid bag for axial shock protection

In view of large loads being needed to protect the axial from the shock situation under small displacement and deformation, a new fluid bag for axial protection was designed in Abaqus. Hydrostatic fluid elements were used to simulate fluid. Interaction between the fluid and bag was simulated with the hydrostatic theory. Based on the finite element theory, the axial stiffness of fluid bag was calculated. The results show that the stiffness had good linearity. The difference between the simulation and experiment results is small, proving the correctness of simulation. The effects of initial bag pressure on the stiffness were discussed. The results indicate that different initial pressures have few impacts on the stiffness as well as tendency of bag pressure variations. Then the effects of bag material properties and fluid bulk modulus on the stiffness were discussed. The results show that both of them are the key factors determining the stiffness. The effects of fluid bag on the stress of a mechanism under axial shock load were discussed. The results show that the fluid bag has a good performance for axial protection