Kinematic and dynamic analysis, and control actions of a hexapod robot were realized for walking, running and bounding gaits in this study. If biological inspiration can be used to build robots that deal robustly with...
详细信息
Kinematic and dynamic analysis, and control actions of a hexapod robot were realized for walking, running and bounding gaits in this study. If biological inspiration can be used to build robots that deal robustly with complex environments, it should be possible to demonstrate that legged biorobots can function in natural environments. Firstly, we tried to report on theoretic work with a six legged robot designed to emulate spider behavior like walking, running and bounding. We demonstrated theoretically that it can successfully walk, run and bound like a spider over natural terrain. Secondly, limitations in its capability were evaluated, and many biologically based important improvements were obtained for future experimental work. Thirdly, the hexapod robot with bounding gait was controlled by proportional-derivative control algorithm and was carried out by using spring loaded inverted pendulum model. Consequently, the developed kinematic and dynamic methods, and control action method makes both the system control easy and the system performance is improved by decreasing the run time for each loop. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.
We developed an effective intelligent model to predict the dynamic heat supply of heat source. A hybrid forecasting method was proposed based on support vector regression (SVR) model-optimized particle swarm optimizat...
详细信息
We developed an effective intelligent model to predict the dynamic heat supply of heat source. A hybrid forecasting method was proposed based on support vector regression (SVR) model-optimized particle swarm optimization (PSO) algorithms. Due to the interaction of meteorological conditions and the heating parameters of heating system, it is extremely difficult to forecast dynamic heat supply. Firstly, the correlations among heat supply and related influencing factors in the heating system were analyzed through the correlation analysis of statistical theory. Then, the SVR model was employed to forecast dynamic heat supply. In the model, the input variables were selected based on the correlation analysis and three crucial parameters, including the penalties factor, gamma of the kernel RBF, and insensitive loss function, were optimized by PSO algorithms. The optimized SVR model was compared with the basic SVR, optimized genetic algorithm-SVR (GA-SVR), and artificial neural network (ANN) through six groups of experiment data from two heat sources. The results of the correlation coefficient analysis revealed the relationship between the influencing factors and the forecasted heat supply and determined the input variables. The performance of the PSO-SVR model is superior to those of the other three models. The PSO-SVR method is statistically robust and can be applied to practical heating system.
Protein folding is governed by a variety of molecular forces including hydrophobic and ionic interactions. Less is known about the molecular determinants of protein stability. Here we used a recently developed compute...
详细信息
Protein folding is governed by a variety of molecular forces including hydrophobic and ionic interactions. Less is known about the molecular determinants of protein stability. Here we used a recently developed computer algorithm (pHinder) to investigate the relationship between buried charge and thermostability. Our analysis revealed that charge networks in the protein core are generally smaller in thermophilic organisms as compared to mesophilic organisms. To experimentally test whether core network size influences protein thermostability, we purified 18 paralogous Ras superfamily GTPases from yeast and determined their melting temperatures (T-m, or temperature at which 50% of the protein is unfolded). This analysis revealed a wide range of Tm values (35-63 degrees C) that correlated significantly (R = 0.87) with core network size. These results suggest that thermostability depends in part on the arrangement of ionizable side chains within a protein core. An improved capacity to predict protein thermostability may be useful for selecting the best candidates for protein crystallography, the development of protein-based therapeutics, as well as for industrial enzyme applications.
Facility location and inventory control are critical and highly related problems in the design of logistics system for e-commerce. Meanwhile, the return ratio in Internet sales was significantly higher than in the tra...
详细信息
Facility location and inventory control are critical and highly related problems in the design of logistics system for e-commerce. Meanwhile, the return ratio in Internet sales was significantly higher than in the traditional business. Focusing on the existing problem in e-commerce logistics system, we formulate a closed-loop location-inventory problem model considering returned merchandise to minimize the total cost which is produced in both forward and reverse logistics networks. To solve this nonlinear mixed programming model, an effective two-stage heuristic algorithm named LRCAC is designed by combining Lagrangian relaxation with ant colony algorithm (AC). Results of numerical examples show that LRCAC outperforms ant colony algorithm (AC) on optimal solution and computing stability. The proposed model is able to help managers make the right decisions under e-commerce environment.
A simple antenna selection strategy for multiple-input multiple-output wireless systems with partial feedback is presented. In the proposed scheme, both transmit and receive antenna selection are done at the receiver,...
详细信息
A simple antenna selection strategy for multiple-input multiple-output wireless systems with partial feedback is presented. In the proposed scheme, both transmit and receive antenna selection are done at the receiver, significantly reducing feedback information. In addition, this scheme uses row/column probability density function for antenna selection to reduce computational complexity without performance degradation. Unlike other schemes, two different antenna selection algorithms are used in high and low signal-to-noise ratio regimes, respectively, achieving additional performance gain in comparison to the single antenna selection algorithm. Simulation results show that the proposed scheme nearly approaches the optimal closed-loop capacity (known as water-filling capacity) as random selection round for antenna selection increases.
The problem of fast data processing for the bi-polar near-field measurement technique is addressed in this paper. A computing algorithm is developed to perform direct far-field transformation from near-field samples a...
详细信息
The problem of fast data processing for the bi-polar near-field measurement technique is addressed in this paper. A computing algorithm is developed to perform direct far-field transformation from near-field samples acquired on the bi-polar scanning surface. Radiation integral is efficiently evaluated by taking advantages of the convolution property leading to use the Fast Fourier Transform and the related shift theorem. The accuracy of the proposed transformation procedure is numerically demonstrated on arrays of infinitesimal dipoles. Results for a measured reflector antenna are also included.
Plenty of hazards underlie complex systems, which have negative effects on the normal functionality of engineering events. To minimize the uncertainty, a comprehensive preevent checkout is necessarily required to judg...
详细信息
Plenty of hazards underlie complex systems, which have negative effects on the normal functionality of engineering events. To minimize the uncertainty, a comprehensive preevent checkout is necessarily required to judge if the engineering events will be carried out successfully under current circumstance, through which further improvements can be made. A generic belief rule-based safety evaluation approach for large-scale complex systems is proposed. The overall system is firstly decomposed and filtered into the measurable attributes that may potentially contribute to uncertainty. Belief structure is then applied to measure the uncertainty of vagueness and incompleteness and represent heterologous information in a unified scheme. With this scheme, a rule base is established with all antecedents, consequents, and attributes presented in belief degrees, which is used to determine the relationship between attributes, aggregate the influences, and generate the final inference with evidential reasoning algorithm. In the end, an estimation of uncertainty is achieved in the representation of distribution. It describes how the systems perform with given conditions and sources. A numeric case in aerospace program is provided for feasibility illustration.
The inherent problem of chattering in traditional sliding mode control is harmful for practical application of control system. This paper pays a considerable attention to a chattering-free control method, that is, hig...
详细信息
The inherent problem of chattering in traditional sliding mode control is harmful for practical application of control system. This paper pays a considerable attention to a chattering-free control method, that is, higher-order sliding mode (super twisting algorithm). The design of a position controller for switched reluctance motor is presented and its stability is assured using Lyapunov stability theorem. In order to highlight the advantages of higher-order sliding mode controller (HOSMC), a classical first-order sliding mode controller (FOSMC) is also applied to the same system and compared. The simulation results reflect the effectiveness of the proposed technique.
This paper proposes a novel quantum-behaved bat algorithm with the direction of mean best position (QMBA). In QMBA, the position of each bat is mainly updated by the current optimal solution in the early stage of sear...
详细信息
This paper proposes a novel quantum-behaved bat algorithm with the direction of mean best position (QMBA). In QMBA, the position of each bat is mainly updated by the current optimal solution in the early stage of searching and in the late search it also depends on the mean best position which can enhance the convergence speed of the algorithm. During the process of searching, quantum behavior of bats is introduced which is beneficial to jump out of local optimal solution and make the quantum-behaved bats not easily fall into local optimal solution, and it has better ability to adapt complex environment. Meanwhile, QMBA makes good use of statistical information of best position which bats had experienced to generate better quality solutions. This approach not only inherits the characteristic of quick convergence, simplicity, and easy implementation of original bat algorithm, but also increases the diversity of population and improves the accuracy of solution. Twenty-four benchmark test functions are tested and compared with other variant bat algorithms for numerical optimization the simulation results show that this approach is simple and efficient and can achieve a more accurate solution.
This paper presents the development and real-time implementation of an auto-white balancing algorithm named scoring. The spectral distributions of the Macbeth reference colors together with the spectral distributions ...
详细信息
This paper presents the development and real-time implementation of an auto-white balancing algorithm named scoring. The spectral distributions of the Macbeth reference colors together with the spectral distributions of several color temperature light sources are used to set up a number of reference color points in the CbCr color space. A number of representative color points are obtained from a captured image by using a previously developed multi-scale clustering algorithm. A match is then established between the reference set of colors and the representative set of colors. The matching scheme generates the most likely color temperature under which the image is captured. Furthermore, this paper discusses the real-time implementation of the developed auto white balancing algorithm on the TI TMS320DSC platform, a power-efficient single-chip processor that has been specifically designed for digital still cameras. It is shown as to how the algorithm is modified to allow a processing rate of 30 frames/s. (C) 2002 Published by Elsevier Science Ltd.
暂无评论