性信息素迷向技术对桃园梨小食心虫的防治效果与分析

连续两年采用梨小食心虫迷向技术在桃园进行了试验观察。结果表明,连片6.7hm2以上的桃园,平均667m2悬挂梨小食心虫迷向丝60枚,可有效的干扰梨小食心虫的交配,减少其后代的种群数量,从而减轻其危害。迷向丝对梨小食心虫各代成虫的迷向率可达97%以上,且持效期在4个月以上,对各代折梢防效在96%以上,蛀果防效在98%以上。全年减少农药使用4～7次。

Design of robust fuzzy controller for ship course-tracking based on RBF network and backstepping approach

This study presents an adaptive fuzzy neural network (FNN) control system for the ship steering autopilot. For the Norrbin ship steering mathematical model with the nonlinear and uncertain dynamic characteristics, an adaptive FNN control system is designed to achieve high-precision track control via the backstepping approach. In the adaptive FNN control system, a FNN backstepping controller is a principal controller which includes a FNN estimator used to estimate the uncertainties, and a robust controller is designed to compensate the shortcoming of the FNN backstepping controller. All adaptive learning algorithms in the adaptive FNN control system are derived from the sense of Lyapunov stability analysis, so that system-tracking stability can be guaranteed in the closed-loop system. The effectiveness of the proposed adaptive FNN control system is verified by simulation results.

Observer-based hybrid control algorithm for semi-active suspension systems

In order to improve ride comfort and handling performance of the vehicle, an adaptive hybrid control algorithm is proposed for semi-active suspension systems. The virtues of sky-hook is combined with ground-hook control strategies and a more suitable compromise for the suspension systems is chosen. The hybrid coefficient is tuned according to the longitudinal and lateral acceleration so as to improve the vehicle stability especially in high speed conditions. Damping continuous adjustable absorber is used to continuously control the damping force so as to eliminate the damping force jerk instead of traditional on-off control policy. Based on suspension stroke measured by sensors, unscented Kalman filter is designed to estimate the suspension states in real-time for the realization of hybrid control, which improves the robustness of the control strategy and is adaptive to different types of road profiles. Finally, the proposed control algorithm is validated under the following two typical road profiles: half-sine speed bump road and the random road. The simulation results indicate that the hybrid control algorithm could offer a good coordination between ride comfort and handling of the vehicle.

Adaptive Finite Element Modeling of Marine Controlled-Source Electromagnetic Fields in Two-Dimensional General Anisotropic Media

In this paper, we extend the scope of numerical simulations of marine controlled-source electromagnetic (CSEM) fields in a particular case of anisotropy (dipping anisotropy) to the general case of anisotropy by using an adaptive finite element approach. In comparison to a dipping anisotropy case, the first order spatial derivatives of the strike-parallel components arise in the partial differential equations for generally anisotropic media, which cause a non-symmetric linear system of equations for finite element modeling. The adaptive finite element method is employed to obtain numerical solutions on a sequence of refined unstructured triangular meshes, which allows for arbitrary model geometries including bathymetry and dipping layers. Numerical results of a 2D anisotropic model show both anisotropy strike and dipping angles have great influence on the marine CSEM responses.

A Control of Uncertain Nonlinear Systems with Unknown Control Direction Via Adaptive Backstepping

The adaptive stabilization problem of nonlinear systems are studied. For a class of uncertain nonlinear systems with unknown control direction, we proposed a robust adaptive backstepping scheme withσ-modification by introducing Nussbaum function and Backstep- ping methods, and proved that all the signals of the closed-loop systems are bounded.

An infrared human face recognition method based on 2DPCA

Aimed at the problems of infrared image recognition under varying illumination,face disguise,etc.,we bring out an infrared human face recognition algorithm based on 2DPCA.The proposed algorithm can work out the covariance matrix of the training sample easily and directly;at the same time,it costs less time to work out the eigenvector.Relevant experiments are carried out,and the result indicates that compared with the traditional recognition algorithm,the proposed recognition method is swift and has a good adaptability to the changes of human face posture.

Adaptive associative classification with emerging frequent patterns

In this paper, we propose an enhanced associative classification method by integrating the dynamic property in the process of associative classification. In the proposed method, we employ a support vector machine（SVM） based method to refine the discovered emerging ~equent patterns for classification rule extension for class label prediction. The empirical study shows that our method can be used to classify increasing resources efficiently and effectively.

Global well-posedness for the dynamical Q-tensor model of liquid crystals

We consider a complex fluid modeling nematic liquid crystal flows, which is described by a system coupling Navier-Stokes equations with a parabolic Q-tensor system. We first prove the global existence of weak solutions in dimension three. Furthermore, the global well-posedness of strong solutions is studied with sufficiently large viscosity of fluid. Finally, we show a continuous dependence result on the initial data which directly yields the weak-strong uniqueness of solutions.

ERROR REDUCTION,CONVERGENCE AND OPTIMALITY OF AN ADAPTIVE MIXED FINITE ELEMENT METHOD

This paper proves the error reduction property （saturation property）, convergence and optimality of an adaptive mixed finite element method （AMFEM） for the Poisson equation. In each step of AMFEM, the local refinement is performed basing on simple either edge-oriented residuals or edge-oriented data oscillations, depending only on the marking strategy, under some restriction of refinement. The main tools used here are the strict discrete local efficiency property given by Carstensen and Hoppe （2006） and the quasi-orthogonality estimate proved by Chen, Holst, and Xu （2009）. Numerical experiments fully confirm the theoretical analysis.

Robust control for active suspension system under steering condition

To minimize the auto body's posture change caused by steering and uneven road, and improve the vehicle's riding comfort and handling stability, this paper presents an H∞ robust controller of the active suspension system, which considers the effects of different steering conditions on its dynamic performance. The vehicle's vibration in the yaw, roll, pitch and vertical direction and the suspension's dynamic deflection in the steering process are taken into account for the designed H∞ robust controller, and it introduces the frequency weight function to improve the riding comfort in the specific sensitive frequency bands to human body. The proposed robust controller is testified through simulation and steering wheel angle step test. The results show that the active suspension with the designed robust controller can enhance the anti-roll capability of the vehicle, inhibit the changes of the body, and improve the riding comfort of the vehicle under steering condition. The results of this study can provide certain theoretical basis for the research and application of active suspension system.

Drought adaptability of phreatophytes:insight from vertical root distribution in drylands of China

Aims The vertical distribution of plant roots is a comprehensive result of plant adaptation to the environment.Limited knowledge on fine vertical root distributions and complex interactions between roots and environmental variables hinders our ability to reliably predict climatic impacts on vegetation dynamics.This study attempts to understand the drought adaptability of plants in arid areas from the perspective of the relationship between vertical root distribution and surroundings.Methods By analyzing root profiles compiled from published studies,the root vertical profiles of two typical phreatophytes,Tamarix ramosissima and Populus euphratica,and their relationships with environmental factors were investigated.A conceptual model was adopted to link the parameter distribution frequency with plant drought adaptability.Important Findings The strong hydrotropism(groundwater-dependent)and flexible water-use strategy of T.ramosissima and P.euphratica help both species survive in hyperarid climates.The differences in the developmental environments between T.ramosissima and P.euphratica can be explained well by the different distribution characteristics of root profiles.That is,higher root plasticity helps T.ramosissima develop a more efficient water-use strategy and therefore survive in more diverse climatic and soil conditions than P.euphratica.We conclude that the higher variation in root profile characteristics of phreatophytes can have greater root adaptability to the surroundings and thus wider hydrological niches and stronger ecological resilience.The inadequacy of models in describing root plasticity limits the accuracy of predicting the future response of vegetation to climate change,which calls for developing process-based dynamic root schemes in Earth system models.