Objective: To estimate the effect of statins use on the prevention of venous thromboembolism (VTE). Methods: We systematically searched MEDLINE (1980-June 2012), EMBASE (1980-June 2012), Google Scholar, Cochrane Libra...Objective: To estimate the effect of statins use on the prevention of venous thromboembolism (VTE). Methods: We systematically searched MEDLINE (1980-June 2012), EMBASE (1980-June 2012), Google Scholar, Cochrane Library, and ISI Web of Science, manually reviewed references, and contacted experts. Case-control studies and cohort studies that compared any dose of statin with no statin or placebo are included. Data extraction and study quality evaluation were independently conducted in duplicate. Results: 12 studies including four cohort studies and eight case-control studies were identified and eligible for meta-analysis. Upon meta-analysis, statin use was associated with a statistically significant reduction in the odds of developing VTE (OR 0.91, 95% CI 0.86-0.96). Conclusion: This meta-analysis of current and available literature suggests that statins can reduce patient's risk of developing VTE. Due to the limitations of observational study, this conclusion should be considered with caution, and additionally, specifical well-designed trials are needed.展开更多
Thinking of grey group model is the improvement on the traditional grey model. It does not merely use a grey model as the ultimate basis, but takes full account of the traditional GM （1,1） model and the GM （1, n） ...Thinking of grey group model is the improvement on the traditional grey model. It does not merely use a grey model as the ultimate basis, but takes full account of the traditional GM （1,1） model and the GM （1, n） model and join two predictions to form a prediction interval. So, the results are more reasonable and more realistic requirements and have strong guidance and reference. The farther the forecast period is, the worse the forecast is. The forecasts in the forecast period of 1-3 Years are the best, but the results of long-term are only as a reference value and the guidance data. Therefore, as the forecast period goes on, rolling grey model is used to increase accuracy.展开更多
One of the most important issues relating to the economic activity of an enterprise is a reliable valuation of assets. It is also one of the key elements in the condition of bankruptcy risk. The aim of this paper is t...One of the most important issues relating to the economic activity of an enterprise is a reliable valuation of assets. It is also one of the key elements in the condition of bankruptcy risk. The aim of this paper is to present the results of the author＇s empirical research concerning the usefulness of the estimates in the valuation of fixed assets held by the enterprises facing bankruptcy. The empirical research was carried out on a group of 100 companies on which courts declared bankruptcy in 2011 in Poland. The study sample constitutes 14% of the population and is a significant representation of the phenomenon. For comparisons of the carrying amounts and the estimated values, the assets recognized in the balance sheet under ＂property, plant, and equipment （PPE）＂ were selected. During the first stage of the research, the significance of PPE in bankruptcy proceedings was confirmed by comparing the share of their value within the estate with the costs of the proceedings recorded as a percentage of the value of the debtor＇s estate. In the next stage of the research, comparisons between the carrying amounts and the estimated values were made. Simple regression models were constructed. The research results confirm that in the case of a substantial doubt about an entity＇s ability to continue as a going concern, the informative value of financial statements is limited and the estimates of the fixed assets value are of fundamental importance.展开更多
In this paper,a two-layer hierarchical structure of optimization and control for polypropylene grade transition was raised to overcome process uncertain disturbances that led to the large deviation between the open-lo...In this paper,a two-layer hierarchical structure of optimization and control for polypropylene grade transition was raised to overcome process uncertain disturbances that led to the large deviation between the open-loop reference trajectory and the actual process.In the upper layer,the variant time scale based control vector parametric methods(VTS-CVP) was used for dynamic optimization of transition reference trajectory,while nonlinear model predictive controller(NMPC) based on closed-loop subspace and piece-wise linear(SSARX-PWL) model in the lower layer was tracking to the reference trajectory from the upper layer for overcoming high-frequency disturbances.Besides,mechanism about trajectory deviation detection and optimal trajectory updating online were introduced to ensure a smooth transition for the entire process.The proposed method was validated with the real data from an industrial double-loop propylene polymerization reaction process with developed dynamic mechanism mathematical model.展开更多
For the two-level five-phase permanent magnet synchronous motor(FP-PMSM)drive system,an improved finite-control-set model predictive torque control(MPTC)strategy is adopted to reduce torque ripple and improve the cont...For the two-level five-phase permanent magnet synchronous motor(FP-PMSM)drive system,an improved finite-control-set model predictive torque control(MPTC)strategy is adopted to reduce torque ripple and improve the control performance of the system.The mathematical model of model reference adaptive system(MRAS)of FP-PMSM is derived and a method based on fractional order sliding mode(FOSM)is proposed to construct the model reference adaptive system(FOSMMRAS)to improve the motor speed estimation accuracy and eliminate the sliding mode integral saturation effect.The simulation results show that the FP-PMSM speed sensorless FCS-MPTC system based on FOSM-MRAS has strong robustness,good dynamic performance and static performance,and high reliability.展开更多
文摘Objective: To estimate the effect of statins use on the prevention of venous thromboembolism (VTE). Methods: We systematically searched MEDLINE (1980-June 2012), EMBASE (1980-June 2012), Google Scholar, Cochrane Library, and ISI Web of Science, manually reviewed references, and contacted experts. Case-control studies and cohort studies that compared any dose of statin with no statin or placebo are included. Data extraction and study quality evaluation were independently conducted in duplicate. Results: 12 studies including four cohort studies and eight case-control studies were identified and eligible for meta-analysis. Upon meta-analysis, statin use was associated with a statistically significant reduction in the odds of developing VTE (OR 0.91, 95% CI 0.86-0.96). Conclusion: This meta-analysis of current and available literature suggests that statins can reduce patient's risk of developing VTE. Due to the limitations of observational study, this conclusion should be considered with caution, and additionally, specifical well-designed trials are needed.
文摘Thinking of grey group model is the improvement on the traditional grey model. It does not merely use a grey model as the ultimate basis, but takes full account of the traditional GM （1,1） model and the GM （1, n） model and join two predictions to form a prediction interval. So, the results are more reasonable and more realistic requirements and have strong guidance and reference. The farther the forecast period is, the worse the forecast is. The forecasts in the forecast period of 1-3 Years are the best, but the results of long-term are only as a reference value and the guidance data. Therefore, as the forecast period goes on, rolling grey model is used to increase accuracy.
文摘One of the most important issues relating to the economic activity of an enterprise is a reliable valuation of assets. It is also one of the key elements in the condition of bankruptcy risk. The aim of this paper is to present the results of the author＇s empirical research concerning the usefulness of the estimates in the valuation of fixed assets held by the enterprises facing bankruptcy. The empirical research was carried out on a group of 100 companies on which courts declared bankruptcy in 2011 in Poland. The study sample constitutes 14% of the population and is a significant representation of the phenomenon. For comparisons of the carrying amounts and the estimated values, the assets recognized in the balance sheet under ＂property, plant, and equipment （PPE）＂ were selected. During the first stage of the research, the significance of PPE in bankruptcy proceedings was confirmed by comparing the share of their value within the estate with the costs of the proceedings recorded as a percentage of the value of the debtor＇s estate. In the next stage of the research, comparisons between the carrying amounts and the estimated values were made. Simple regression models were constructed. The research results confirm that in the case of a substantial doubt about an entity＇s ability to continue as a going concern, the informative value of financial statements is limited and the estimates of the fixed assets value are of fundamental importance.
基金Supported by the Electronic Information Industry Development Foundation of China(20140806)the National Natural Science Foundation of China(61374121,61134007)
文摘In this paper,a two-layer hierarchical structure of optimization and control for polypropylene grade transition was raised to overcome process uncertain disturbances that led to the large deviation between the open-loop reference trajectory and the actual process.In the upper layer,the variant time scale based control vector parametric methods(VTS-CVP) was used for dynamic optimization of transition reference trajectory,while nonlinear model predictive controller(NMPC) based on closed-loop subspace and piece-wise linear(SSARX-PWL) model in the lower layer was tracking to the reference trajectory from the upper layer for overcoming high-frequency disturbances.Besides,mechanism about trajectory deviation detection and optimal trajectory updating online were introduced to ensure a smooth transition for the entire process.The proposed method was validated with the real data from an industrial double-loop propylene polymerization reaction process with developed dynamic mechanism mathematical model.
基金National Natural Science Foundation of China(No.51867012)。
文摘For the two-level five-phase permanent magnet synchronous motor(FP-PMSM)drive system,an improved finite-control-set model predictive torque control(MPTC)strategy is adopted to reduce torque ripple and improve the control performance of the system.The mathematical model of model reference adaptive system(MRAS)of FP-PMSM is derived and a method based on fractional order sliding mode(FOSM)is proposed to construct the model reference adaptive system(FOSMMRAS)to improve the motor speed estimation accuracy and eliminate the sliding mode integral saturation effect.The simulation results show that the FP-PMSM speed sensorless FCS-MPTC system based on FOSM-MRAS has strong robustness,good dynamic performance and static performance,and high reliability.
