Dynamics of a Predator-Prey Ecological System with Nonlinear Harvesting Rate

In this paper, a predator-prey ecological economic system with nonlinear harvesting rate is formulated and studied. This system is described by a differential-algebraic equation. By employing local parameterization method, an equivalent differen- tial system with parameter is obtained. Then by normal form the-ory and bifurcation theory, the complex dynamics of the system are investigated, including the local stability of equilibrium point and Hopf bifurcation. Finally, MATLAB simulation illustrates the effectiveness of our results.

Sensing Time Optimization in Energy-Harvesting Cognitive Radio with Interference Rate Control

In this paper,an energy-harvesting cognitive radio(CR) is considered,which allows the transmitter of the secondary user(SU) to harvest the primary signal energy from the transmitter of the primary user(PU) when the presence of the PU is detected.Then the harvested energy is converted into the electrical power to supply the transmission of the SU at the detected absence of the PU.By adopting the periodic spectrum sensing,the average total transmission rate of the SU is maximized through optimizing the sensing time,subject to the constraints of the probabilities of false alarm and detection,the harvested energy and the interference rate control.The simulation results show that there deed exists an optimal sensing time that maximizes the transmission rate,and the maximum transmission rate of the energy-harvesting CR can better approach to that of the traditional CR with the increasing of the detection probability.

Effects of Different Vibration Intensities Harvesting on Photosynthesis System Parameters of Lycium barbarum L. Trees with Harvest Machine

The effects of different vibration intensities harvesting on photosynthesis system parameters of Lycium barbarum L. tree with harvest machine were researched. The result showed that the photosynthetic rate, transpiration rate, stomata conductance and intercellular CO2 concentration of L. barbarum tree＇s leaves under different treatment during different periods have no significant difference compared with contrast. It indicates that there is no significant effect on photosynthesis system parameters of L. barbarum tree＇s leaves with harvest machine.

A Survey about Algorithms Utilized by Focused Web Crawler

Abstract—Focused crawlers （also known as subjectoriented crawlers）, as the core part of vertical search engine, collect topic-specific web pages as many as they can to form a subject-oriented corpus for the latter data analyzing or user querying. This paper demonstrates that the popular algorithms utilized at the process of focused web crawling, basically refer to webpage analyzing algorithms and crawling strategies （prioritize the uniform resource locator （URLs） in the queue）. Advantages and disadvantages of three crawling strategies are shown in the first experiment, which indicates that the best-first search with an appropriate heuristics is a smart choice for topic-oriented crawlingwhile the depth-first search is helpless in focused crawling. Besides, another experiment on comparison of improved ones （with a webpage analyzing algorithm added） is carried out to verify that crawling strategies alone are not quite efficient for focused crawling and in most cases their mutual efforts are taken into consideration. In light of the experiment results and recent researches, some points on the research tendency of focused crawler algorithms are suggested.