Rolling texture and its effect on tensile property of a near-α titanium alloy Ti60 plate

Rolling texture and its effect on tensile properties of Ti60 alloy plates were investigated in the present study. The plates wereβ-rolled at 1070℃ and(α+β)-rolled at 980℃, using uni-directionally rolling(UDR) and cross-directionally rolling(CDR) processes, respectively.β-rolled plates exhibited weak textures, which were attributed to the dispersive orientations of secondary α during the β→α phase transformation. Strong deformation textures formed in(α+β)-rolled plates as a result of slipping mechanisms: the strong T-type texture in UDR plate was related to {10 1 0}[11 2 0] slipping, while the B-type texture in CDR plate was relevant with {0001}[11 2 0] slip. Strong T-type textures led to anisotropic tensile properties. B-type textures would decrease such an anisotropy. The(α+β)-CDR process was found to be a candidate process for reducing anisotropy of Ti60 alloy plates.     

Efficient defect-controlled photocatalytic hydrogen generation based on near-infrared Cu-In-Zn-S quantum dots

The development of photocatalysts that can effectively harvest visible light is essential for advances in high-efficiency solar-driven hydrogen generation. Herein, we synthesized water soluble CuInS₂ (CIS) and Cu-In-Zn-S (CIZS) quantum dots (QDs) by using one-pot aqueous method. The CIZS QDs are well passivated by glutathione ligands and are highly stable in aqueous conditions. We subsequently applied these QDs as a light harvesting material for photocatalytic hydrogen generation. Unlike most small band gap materials that show extremely low efficiency, these new QDs display remarkable energy conversion efficiency in the visible and near-infrared regions. The external quantum efficiency at 650 nm is ～1.5%, which, to the best of our knowledge, is the highest value achieved until now in the near-infrared region.

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S型异质结BiOBr/ZnMoO4的构建及光催化降解性能研究

光催化被广泛用于去除水中的难降解有机污染物,但是由于光生电子和空穴的复合率高,抑制了半导体光催化剂的催化活性。本研究通过简便的溶剂热法成功制备了一种BiOBr/ZnMoO₄复合材料。通过结构分析、原位XPS、功函数测试、自由基捕获及电子顺磁共振(ESR)实验等证实了BiOBr/ZnMoO₄复合材料形成了S型异质结。实验结果表明,适当ZnMoO₄含量的BiOBr/ZnMoO₄异质结可以显著提高BiOBr的光催化性能。与纯BiOBr、ZnMoO₄相比,质量分数15%BiOBr/ZnMoO₄在可见光下表现出最佳的光催化活性,双酚A的光催化降解率达到85.3%(90min),环丙沙星的光降解速率常数分别是BiOBr的2.6倍和ZnMoO₄的484倍。这可归因于BiOBr和ZnMoO₄之间形成了紧密的界面结合和S型异质结,使得光生载流子可以实现有效的空间分离和转移。这项工作为定向合成Bi基S型异质结复合光催化材料提供了一种...     

Modeling and Neuro-Fuzzy adaptive attitude control for Eight-Rotor MAV

This paper focuses on modeling and intelligent control of the new Eight-Rotor MAV which is used to solve the problem of low coefficient proportion between lift and gravity for Quadrotor MAV. The dynamical and kinematical modeling for the Eight-Rotor MAV was developed which has never been proposed before. Based on the achieved dynamic modeling, two types of controller were presented. One type, a PID controller is derived in a conventional way with simplified dynamics and turns out to be quite sensitive to sensor noise as well as external perturbation. The second type controller is the Neuro-Fuzzy adaptive controller which is composed of two type-II fuzzy neural networks (TIIFNNs) and one PD controller: The PD controller is adopted to control the attitude, one of the TIIFNNs is designed to learn the inverse model of Eight-Rotor MAV on-line, the other one is the copy of the former one to compensate for model errors and external disturbances, both structure and parameters of T-IIFNNs are tuned on-line at the same time, and then the stability of the Eight-Rotor MAV closed-loop control system is proved using Lyapunov stability theory. Finally, the validity of the proposed control method has been verified through real-time experiments. The experimental results show that the performance of Neuro-Fuzzy adaptive controller performs very well under sensor noise and external disturbances, and has more superiority than traditional PID controller.     

Indeterminacy-aware service selection for reliable service composition

With the development of Internet and Web service technology, Web service composition has been an effective way to construct software applications; service selection is the crucial element in the composition process. However, the existing selection methods mostly generate static plans since they neglect the inherent stochastic and dynamic nature of Web services. As a result, Web service composition often inevitably terminates with failure. An indeterminacy-aware service selection algorithmbased on an improved Markov decision process (IMDP) has been designed for reliable service composition, but it suffers from higher computation complexity. Therefore, an efficient method is proposed, which can reduce the computation cost by converting the service selection problem based on IMDP into solving a nonhomogeneous linear equation set. Experimental results demonstrate the success rate of service composition has been improved greatly, whilst also reducing computation cost.     

Adaptive robust coordinated control of multiple mobile manipulators interacting with rigid environments

In this paper, we consider multiple mobile manipulators grasping a common object in contact with a rigid surface, and propose a new version of adaptive robust control extended to the actuator level for multiple mobile manipulators carrying a common object in a cooperative manner. The proposed controls are robust not only to parametric uncertainties including mass variation and electrical parameters but also to external disturbances. Simulation results are presented to validate that the motion/force tracking errors converge to zero whereas the internal force tracking error remains bounded and can be made arbitrarily small.     

Information diffusion-based spatio-temporal risk analysis of grassland fire disaster in northern China

This study presents a Geographical Information Systems (GIS) and information diffusion-based methodology for spatio-temporal risk analysis of grassland fire disaster to livestock production in the grassland area of the northern China. We employed information matrix to analyze and to quantify fuzzy relationship between the number of annual severe grassland fire disasters and annual burned area. We also evaluated the consequences of grassland fire disaster between 1991 and 2006 based on historical data from 12 northern China provinces. The results show that the probabilities of annual grassland fire disasters and annual damage rates on different levels increase gradually from southwest to northeast across the northern China. The annual burned area can be predicted effectively using the number of annual severe grassland fire disasters. The result shows reliability as tested by two-tailed Pearson correlation coefficient. This study contributes a reference in decision making for prevention of grassland fire disaster and for stockbreeding sustainable development planning. The fuzzy relationship could provide information to make compensation plan for the disaster affected area.     

Predicting protein secondary structure using a mixed-modal SVM method in a compound pyramid model

Accurate protein secondary structure prediction plays an important role in direct tertiary structure modeling, and can also significantly improve sequence analysis and sequence-structure threading for structure and function determination. Hence improving the accuracy of secondary structure prediction is essential for future developments throughout the field of protein research.In this article, we propose a mixed-modal support vector machine (SVM) method for predicting protein secondary structure. Using the evolutionary information contained in the physicochemical properties of each amino acid and a position-specific scoring matrix generated by a PSI-BLAST multiple sequence alignment as input for a mixed-modal SVM, secondary structure can be predicted at significantly increased accuracy. Using a Knowledge Discovery Theory based on the Inner Cognitive Mechanism (KDTICM) method, we have proposed a compound pyramid model, which is composed of three layers of intelligent interface that integrate a mixed-modal SVM (MMS) module, a modified Knowledge Discovery in Databases (KDD1) process, a mixed-modal back propagation neural network (MMBP) module and so on.Testing against data sets of non-redundant protein sequences returned values for the Q₃ accuracy measure that ranged from 84.0% to 85.6%,while values for the SOV99 segment overlap measure ranged from 79.8% to 80.6%. When compared using a blind test dataset from the CASP8 meeting against currently available secondary structure prediction methods, our new approach shows superior accuracy.Availability: http://www.kdd.ustb.edu.cn/protein_Web/.     

磁敏测速系统的数据采集平台实现

串口同步采集是工业控制应用的重要环节,为克服由于不准确的数据采集所带来的乘性误差,进而对多串口的同步采集进行了研究。利用VS2005编程环境,设计实现了多串口的上位机数据采集平台,该平台开辟线程对多个串口采取重叠读取方式,实现了对测速系统中大量的串口数据同步读取、保存并实现波形动态显示的功能,满足了智能测速系统的测速算法研究的需要。此平台可以广泛的应用在测速系统之中,也可辅助用于各种工业控制的高级要求。     

A fast immersed interface method for solving Stokes flows on irregular domains

We present a fast immersed interface method for solving the steady Stokes flows involving the rigid boundaries. The immersed rigid boundary is represented by a set of Lagrangian control points. In order to enforce the prescribed velocity at the rigid boundary, singular forces at the rigid boundary are applied on the fluid. The forces are related to the jumps in pressure and the jumps in the derivatives of both pressure and velocity, and are approximated using the cubic splines. The strength of singular forces is determined by solving a small system of equations via the GMRES method. The Stokes equations are discretized using finite difference method with the incorporation of jump conditions on a staggered Cartesian grid and solved by the conjugate gradient Uzawa-type method. Numerical results demonstrate the accuracy and ability of the proposed method to simulate Stokes flows on irregular domains.