This paper has investigated best tracking performance for linear feedback control systems in the case that plant uncertainty and control effort need to be considered simultaneously. Firstly, an average integral square...This paper has investigated best tracking performance for linear feedback control systems in the case that plant uncertainty and control effort need to be considered simultaneously. Firstly, an average integral square criterion of the tracking error and the plant input energy over a class of additive model errors is defined. Then, utilizing spectral factorization to minimize the performance index, we obtain an optimal controller design method, and furthermore study optimal tracking performance under plant uncertainty and control energy constraint. The results can be used to evaluate optimal average tracking performance and control energy in designing practical control systems.展开更多
A risk in the prices of fossil fuels is a major concern to importing countries of them. This study analyzes the risk of an increase in the cost for Japanese electric utility sector during the period 1978-2007 consider...A risk in the prices of fossil fuels is a major concern to importing countries of them. This study analyzes the risk of an increase in the cost for Japanese electric utility sector during the period 1978-2007 considering the uncertainty in the prices of fossil fuels. The mean-semivariance model, which uses an upper semivariance as an index of the risk, is adopted for the purpose. The result confirms that the semivariance is the better index of the risk than the variance. Furether, the semivariance is decomposed into two factors; the risk caused by price changes in an individual fossil fuel source and the risk caused by correlations among the changes in the prices of fossil fuel sources. The former has been kept at a low level as it appears to be easy to estimate, while the latter has not been maintained at the lowest level as it appears to be difficult to estimate. The Japanese electric utility sector followed the minimum-risk fossil fuel mix up until 2001, but discontinued the same post 2001.展开更多
OBJECTIVE: To examine German controlled clinical trials on the therapeutic effects of acupuncture vs sham acupuncture, and to find whether there are problems with the conclusion that sham acupuncture has no significan...OBJECTIVE: To examine German controlled clinical trials on the therapeutic effects of acupuncture vs sham acupuncture, and to find whether there are problems with the conclusion that sham acupuncture has no significant deviation from acupuncture. METHODS: We focused on literature from the last ten years (2002-2011) included in PubMed about controlled clinical trials on acupuncture vs sham acupuncture carried out in Germany. The methods applied in sham acupuncture are summarized, and the difference between the acupuncture and sham groups were analyzed. We measured effects based on the following criteria: acupuncture is effective and superior to sham, acupuncture is effective but similar to sham, both of them have uncertainty regarding treatment effect, or no significant effect. Finally, we reviewed the hypotheses of different scholars on sham acupuncture and analyzed their results.RESULTS: Four types of controlled clinical trials including sham acupuncture on non-Traditional Chinese Medicine acupoints, minimal acupuncture on non-acupoints, placebo needle and sham laser acupuncture had varying results in the 57 articles analyzed. Some showed that acupuncture had a better effect than sham, while some suggest acupuncture and sham had similar effects. In all studies using sham acupuncture on non-therapeutic points, sham electrodes, and sham electro-acupuncture, the therapeutic effect was better than sham. Of the trials, 37 demonstrated that acupuncture had a better effect than sham acupuncture. Only nine trials found no significant difference between acupuncture and sham. Two controlled trials for the same condition (neck pain) conducted by two different German research institutes used the same control method, but reached contradictory conclusions. CONCLUSION: We found problems in conclusions based on results of controlled clinical trials of sham acupuncture in Germany. Therefore, there is still not enough evidence to support the statements that "acupuncture and sham acupuncture have no difference in treatment effect" and "acupuncture is just a placebo effect." The control methods of sham acupuncture used in Germany may not be standardized and may not be suitable for acupuncture clinical trial research. We suggest that research on the methodology of sham acupuncture should be given priority in the design of acupuncture trials in the future.展开更多
基金High Technology Research and Development (863) Program(No.2003AA517020)
文摘This paper has investigated best tracking performance for linear feedback control systems in the case that plant uncertainty and control effort need to be considered simultaneously. Firstly, an average integral square criterion of the tracking error and the plant input energy over a class of additive model errors is defined. Then, utilizing spectral factorization to minimize the performance index, we obtain an optimal controller design method, and furthermore study optimal tracking performance under plant uncertainty and control energy constraint. The results can be used to evaluate optimal average tracking performance and control energy in designing practical control systems.
文摘A risk in the prices of fossil fuels is a major concern to importing countries of them. This study analyzes the risk of an increase in the cost for Japanese electric utility sector during the period 1978-2007 considering the uncertainty in the prices of fossil fuels. The mean-semivariance model, which uses an upper semivariance as an index of the risk, is adopted for the purpose. The result confirms that the semivariance is the better index of the risk than the variance. Furether, the semivariance is decomposed into two factors; the risk caused by price changes in an individual fossil fuel source and the risk caused by correlations among the changes in the prices of fossil fuel sources. The former has been kept at a low level as it appears to be easy to estimate, while the latter has not been maintained at the lowest level as it appears to be difficult to estimate. The Japanese electric utility sector followed the minimum-risk fossil fuel mix up until 2001, but discontinued the same post 2001.
基金Supported by the Program of China Academy of Chinese Medical Sciences for Young Researchers in Medical Science(No.ZZ040305)
文摘OBJECTIVE: To examine German controlled clinical trials on the therapeutic effects of acupuncture vs sham acupuncture, and to find whether there are problems with the conclusion that sham acupuncture has no significant deviation from acupuncture. METHODS: We focused on literature from the last ten years (2002-2011) included in PubMed about controlled clinical trials on acupuncture vs sham acupuncture carried out in Germany. The methods applied in sham acupuncture are summarized, and the difference between the acupuncture and sham groups were analyzed. We measured effects based on the following criteria: acupuncture is effective and superior to sham, acupuncture is effective but similar to sham, both of them have uncertainty regarding treatment effect, or no significant effect. Finally, we reviewed the hypotheses of different scholars on sham acupuncture and analyzed their results.RESULTS: Four types of controlled clinical trials including sham acupuncture on non-Traditional Chinese Medicine acupoints, minimal acupuncture on non-acupoints, placebo needle and sham laser acupuncture had varying results in the 57 articles analyzed. Some showed that acupuncture had a better effect than sham, while some suggest acupuncture and sham had similar effects. In all studies using sham acupuncture on non-therapeutic points, sham electrodes, and sham electro-acupuncture, the therapeutic effect was better than sham. Of the trials, 37 demonstrated that acupuncture had a better effect than sham acupuncture. Only nine trials found no significant difference between acupuncture and sham. Two controlled trials for the same condition (neck pain) conducted by two different German research institutes used the same control method, but reached contradictory conclusions. CONCLUSION: We found problems in conclusions based on results of controlled clinical trials of sham acupuncture in Germany. Therefore, there is still not enough evidence to support the statements that "acupuncture and sham acupuncture have no difference in treatment effect" and "acupuncture is just a placebo effect." The control methods of sham acupuncture used in Germany may not be standardized and may not be suitable for acupuncture clinical trial research. We suggest that research on the methodology of sham acupuncture should be given priority in the design of acupuncture trials in the future.
