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Copyright of Guangdong Agricultural Sciences is the property of South China Agricultural University, Guangdong Academy of Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Oilfield Chemistry is the property of Sichuan University, Oilfield Chemistry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plant gum thickening agents and their derivatives used in water based fracturing fluids have some shortages such as high residue content, poor thermal stability and easy spoilage. To solve these problems, a new thickening agent was developed with acrylamide (AM), a functional monomer SP and 2-Acrylamido-2-methylpropane sulfonic acid (AMPS) as the reaction monomers. In laboratory synthesis of this new thickening agent, based on the free radical polymerization of water-soluble polymer theory, the effects of the various synthesis conditions (such as concentration of the initiator, reaction temperature, pH of the reaction system, polymer concentration, content of the chain transfer agent and the degree of hydrolysis) on the performance of the final thickening agent were studied. Using the method of control variates, the reaction conditions are as follows: Polymer concentration = 25%, ratio of monomers (AMPS∶SP∶AM) = 30%∶25%∶45%, reaction temperature = 20 ℃, concentration of initiator = 0.3%, pH = 7, mass fraction of sodium formate = 0.2%, reaction time = 4 h. The thickening agent synthesized has good high temperature resistance, low water insoluble and high thickening capacity. It is instantly soluble and can be easily crosslinked with the organozirconium crosslinking agent. This thickening agent can be used in formation temperatures as high as 200 ℃. [ABSTRACT FROM AUTHOR]

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to solve the tracking control problem of the uncertain chaotic system with immeasurable states and unknown system functions, a backstepping adaptive sliding mode control strategy based on ESO ( extended state observer) was proposed for uncertain chaotic system. Through a nonlinear coordinate transformation, the normal chaotic model was transformed into a parametric-strict-feedback form, which was more suitable for the backstepping design strategy. A linear ESO is designed to estimate the unknown states and the total uncertainties. Whereafter, a backstepping sliding mode control law and an adaptive law of switch gain were simultaneously designed to guarantee that the tracking errors can converge to zero rapidly and stably. And then, the derivatives of the virtual control were computed by applying a filter without having to analytically or numerically differentiate it. Therefore, the backstepping implementation was significantly simplified. Simulation results show that the proposed adaptive sliding mode controller can improve the chattering problem of the traditional sliding mode control, and enhance the dynamic performance of the system, in comparison with the traditional PID and the traditional sliding mode control. [ABSTRACT FROM AUTHOR]

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Vibration Engineering is the property of Nanjing University of Aeronautics & Astronautics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Sciencepaper is the property of China Sciencepaper and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Petroleum Geology & Recovery Efficiency is the property of Petroleum Geology & Recovery Efficiency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

According to operation environment and the present situation in the scheduling of public traffic vehicle, signal lamp cycle is taken into account the effect of waiting time of passengers in this paper. A bus optimization scheduling model is built, and it can ensure bus company's economic and passengers' benefits at the same time. According to the problem of low efficiency by the refused strategy, a new fitness function is designed by the penalty strategy. Based on the problems of the simple genetic algorithm in premature convergence and easily getting into local optimum and so on, combining quantum computation with genetic algorithm, quantum genetic algorithm which increases the convergence velocity and good global search capacity is put forward in this paper. Research result shows that the algorithm can effectively solve the combining problems of the bus optimization scheduling. [ABSTRACT FROM AUTHOR]