A multi-mode adaptive controller was proposed. The controller features in thecombination of Bang-bang and Fuzzy PID controls with state predictor. When large error exists, thecontroller operates in Bang-bang mode, oth...A multi-mode adaptive controller was proposed. The controller features in thecombination of Bang-bang and Fuzzy PID controls with state predictor. When large error exists, thecontroller operates in Bang-bang mode, otherwise it works as a fuzzy PID controller. For only fewparameters to be adjusted, the real time controlled system achieveed good stability and fastresponse. Furthermore, the introduction of state observer was also discussed to extend thecapability of the proposed controller to the plant with time-delay factors. The classical PIDcontroller and the multi-mode controller were applied to the same second-order system successively.By comparison of the simulation results, the effectiveness of the controller were shown. At last, onelectric-wire production line, this approach was practiced to control electric-wire diameter withan additive random disturbance signal. The test result further proved the effectiveness of themulti-mode controller.展开更多
<strong>Background:</strong> <span style="font-family:;" "=""><span style="font-family:Verdana;">One of the key strategies in the HIV/AIDS prevention and cont...<strong>Background:</strong> <span style="font-family:;" "=""><span style="font-family:Verdana;">One of the key strategies in the HIV/AIDS prevention and control programs in Nigeria is Voluntary HIV counseling and testing (VCT). However, its utilization among young adults, particularly undergraduates, is very low. The aim of the present study was to determine the prevalence and predictors of non-uptake of VCT among undergraduates. </span><b><span style="font-family:Verdana;">Methods: </span></b><span style="font-family:Verdana;">A cross sectional study using quantitative methods was conducted. Using simple random sampling, three faculties were selected out of nine and 422 respondents were selected from three faculties. Interviews were conducted using pre-tested semi-structured questionnaires. Data analysis was done using statistical package for social sciences version 20. Prevalence was measured by the percentage of respondents that had never used VCT. Analytical statistics were done using chi-square test to measure strength of association between VCT uptake and knowledge and attitude of respondents. Association with P-value</span></span><span> </span><span style="font-family:Verdana;"> < </span><span> </span><span style="font-family:Verdana;">0.05 was considered significant.</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> Logistic regression was used to identify predictors of non-uptake of VCT. The associations were presented as odds ratios (OR) and 95% confidence intervals.</span><b><span style="font-family:Verdana;"> Results: </span></b><span style="font-family:Verdana;">Overall, 59.3% of respondents were knowledgeable about VCT while majority, 64.7% had negative attitude towards it. Knowledge (X</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> = 9.89, P-value < 0.001) and attitude (X</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> = 10.78, P-value < 0.001) showed statistically significant association with VCT uptake. The prevalence of non-uptake of VCT among the respondents was 82.7%. Ignorance, fear of positive test, stigma and discrimination were found to be strong predictors of non-uptake of VCT.</span><b> </b><span style="font-family:Verdana;">OR 1.874 (1.058 - 3.289), P < 0.001;OR 2.455 (1.308 - 4.608), P < 0.000 and OR 2.318 (1.299 - 4.128), P < 0.000 respectively. </span><b><span style="font-family:Verdana;">Conclusions: </span></b><span style="font-family:Verdana;">VCT uptake among undergraduates was low and determined by VCT-related ignorance, poor attitude, fear of positive result and HIV/AIDS-related stigma/discrimination. In order to change the narrative, HIV/AIDS prevention and control programs in Nigeria should address the identified predictors of non-VCT uptake. There is a need to focus on young adults when designing, expanding and implementing VCT services in the country.</span></span>展开更多
Based on a nonlinear state predictor (NSP) and a strong tracking filter (STF), a sensor fault tolerant generic model control (FTGMC) approach for a class of nonlinear time-delay processes is proposed. First, the NSP i...Based on a nonlinear state predictor (NSP) and a strong tracking filter (STF), a sensor fault tolerant generic model control (FTGMC) approach for a class of nonlinear time-delay processes is proposed. First, the NSP is introduced, and it is used to extend the conventional generic model control (GMC) to nonlinear processes with large input time-delay. Then the STF is adopted to estimate process states and sensor bias, the estimated sensor bias is used to drive a fault detection logic. When a sensor fault is detected, the estimated process states by the STF will be used to construct the process output to form a 'soft sensor', which is then used by the NSP (instead of the real outputs) to provide state predictors. These procedures constitute an active fault tolerant control scheme. Finally, simulation results of a three-tank-system demonstrate the effectiveness of the proposed approach.展开更多
基金This research was financially supported by the Open Fund of the Fieldbus tech& Automation Beijing Key Lab (No.2002.19-21).
文摘A multi-mode adaptive controller was proposed. The controller features in thecombination of Bang-bang and Fuzzy PID controls with state predictor. When large error exists, thecontroller operates in Bang-bang mode, otherwise it works as a fuzzy PID controller. For only fewparameters to be adjusted, the real time controlled system achieveed good stability and fastresponse. Furthermore, the introduction of state observer was also discussed to extend thecapability of the proposed controller to the plant with time-delay factors. The classical PIDcontroller and the multi-mode controller were applied to the same second-order system successively.By comparison of the simulation results, the effectiveness of the controller were shown. At last, onelectric-wire production line, this approach was practiced to control electric-wire diameter withan additive random disturbance signal. The test result further proved the effectiveness of themulti-mode controller.
文摘<strong>Background:</strong> <span style="font-family:;" "=""><span style="font-family:Verdana;">One of the key strategies in the HIV/AIDS prevention and control programs in Nigeria is Voluntary HIV counseling and testing (VCT). However, its utilization among young adults, particularly undergraduates, is very low. The aim of the present study was to determine the prevalence and predictors of non-uptake of VCT among undergraduates. </span><b><span style="font-family:Verdana;">Methods: </span></b><span style="font-family:Verdana;">A cross sectional study using quantitative methods was conducted. Using simple random sampling, three faculties were selected out of nine and 422 respondents were selected from three faculties. Interviews were conducted using pre-tested semi-structured questionnaires. Data analysis was done using statistical package for social sciences version 20. Prevalence was measured by the percentage of respondents that had never used VCT. Analytical statistics were done using chi-square test to measure strength of association between VCT uptake and knowledge and attitude of respondents. Association with P-value</span></span><span> </span><span style="font-family:Verdana;"> < </span><span> </span><span style="font-family:Verdana;">0.05 was considered significant.</span><span style="font-family:;" "=""><span style="font-family:Verdana;"> Logistic regression was used to identify predictors of non-uptake of VCT. The associations were presented as odds ratios (OR) and 95% confidence intervals.</span><b><span style="font-family:Verdana;"> Results: </span></b><span style="font-family:Verdana;">Overall, 59.3% of respondents were knowledgeable about VCT while majority, 64.7% had negative attitude towards it. Knowledge (X</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> = 9.89, P-value < 0.001) and attitude (X</span><sup><span style="font-family:Verdana;">2</span></sup><span style="font-family:Verdana;"> = 10.78, P-value < 0.001) showed statistically significant association with VCT uptake. The prevalence of non-uptake of VCT among the respondents was 82.7%. Ignorance, fear of positive test, stigma and discrimination were found to be strong predictors of non-uptake of VCT.</span><b> </b><span style="font-family:Verdana;">OR 1.874 (1.058 - 3.289), P < 0.001;OR 2.455 (1.308 - 4.608), P < 0.000 and OR 2.318 (1.299 - 4.128), P < 0.000 respectively. </span><b><span style="font-family:Verdana;">Conclusions: </span></b><span style="font-family:Verdana;">VCT uptake among undergraduates was low and determined by VCT-related ignorance, poor attitude, fear of positive result and HIV/AIDS-related stigma/discrimination. In order to change the narrative, HIV/AIDS prevention and control programs in Nigeria should address the identified predictors of non-VCT uptake. There is a need to focus on young adults when designing, expanding and implementing VCT services in the country.</span></span>
基金Supported by the National Natural Science Foundation of China (No. 60025307, No. 60234010) the National 863 Project(No. 2001AA413130,2002AA412420)+1 种基金 Research Fund for the Doctoral Program of Higher Education (No. 20020003063) the National 973 Program
文摘Based on a nonlinear state predictor (NSP) and a strong tracking filter (STF), a sensor fault tolerant generic model control (FTGMC) approach for a class of nonlinear time-delay processes is proposed. First, the NSP is introduced, and it is used to extend the conventional generic model control (GMC) to nonlinear processes with large input time-delay. Then the STF is adopted to estimate process states and sensor bias, the estimated sensor bias is used to drive a fault detection logic. When a sensor fault is detected, the estimated process states by the STF will be used to construct the process output to form a 'soft sensor', which is then used by the NSP (instead of the real outputs) to provide state predictors. These procedures constitute an active fault tolerant control scheme. Finally, simulation results of a three-tank-system demonstrate the effectiveness of the proposed approach.
