Annual arrhythmic sudden cardiac death ranges from 0.6%to 4%in ischemic cardiomyopathy(ICM),1%to 2%in non-ischemic cardiomyopathy(NICM),and 1%in hypertrophic cardiomyopathy(HCM).Towards a more effective arrhythmic ris...Annual arrhythmic sudden cardiac death ranges from 0.6%to 4%in ischemic cardiomyopathy(ICM),1%to 2%in non-ischemic cardiomyopathy(NICM),and 1%in hypertrophic cardiomyopathy(HCM).Towards a more effective arrhythmic risk stratification(ARS)we hereby present a two-step ARS with the usage of seven non-invasive risk factors:Late potentials presence(≥2/3 positive criteria),premature ventricular contractions(≥30/h),non-sustained ventricular tachycardia(≥1episode/24 h),abnormal heart rate turbulence(onset≥0%and slope≤2.5 ms)and reduced deceleration capacity(≤4.5 ms),abnormal T wave alternans(≥65μV),decreased heart rate variability(SDNN<70ms),and prolonged QT_(c)interval(>440 ms in males and>450 ms in females)which reflect the arrhythmogenic mechanisms for the selection of the intermediate arrhythmic risk patients in the first step.In the second step,these intermediate-risk patients undergo a programmed ventricular stimulation(PVS)for the detection of inducible,truly high-risk ICM and NICM patients,who will benefit from an implantable cardioverter defibrillator.For HCM patients,we also suggest the incorporation of the PVS either for the low HCM Risk-score patients or for the patients with one traditional risk factor in order to improve the inadequate sensitivity of the former and the low specificity of the latter.展开更多
For river basin management, the reliability of the rating curves mainly depends on the accuracy and time period of the observed discharge and water level data. In the Elbe decision support system (DSS), the rating cur...For river basin management, the reliability of the rating curves mainly depends on the accuracy and time period of the observed discharge and water level data. In the Elbe decision support system (DSS), the rating curves are combined with the HEC-6 model to investigate the effects of river engineering measures on the Elbe River system. In such situations, the uncertainty originating from the HEC-6 model is of significant importance for the reliability of the rating curves and the corresponding DSS results. This paper proposes a two-step approach to analyze the uncertainty in the rating curves and propagate it into the Elbe DSS: analytic method and Latin Hypercube simulation. Via this approach the uncertainty and sensitivity of model outputs to input parameters are successfully investigated. The results show that the proposed approach is very efficient in investigating the effect of uncertainty and can play an important role in improving decision-making under uncertainty.展开更多
Phononic materials with specific band-gap characteristics at desired frequency ranges are in great demand for vibration and noise isolation, elastic wave filters, and acoustic devices. The attenuation coefficient curv...Phononic materials with specific band-gap characteristics at desired frequency ranges are in great demand for vibration and noise isolation, elastic wave filters, and acoustic devices. The attenuation coefficient curve depicts both the frequency range of band gap and the attenuation of elastic wave, where the frequency ranges corresponding to the none-zero attenuation coefficients are band gaps. Therefore, the band-gap characteristics can be achieved through maximizing the attenuation coefficient at the corresponding frequency or within the corresponding frequency range. Because the attenuation coefficient curve is not smooth in the frequency domain, the gradient-based optimization methods cannot be directly used in the design optimization of phononic band-gap materials to achieve the maximum attenuation within the desired frequency range. To overcome this difficulty, the objective of maximizing the attenuation coefficient is transformed into maximizing its Cosine, and in this way, the objective function is smoothed and becomes differentiable. Based on this objective function, a novel gradient-based optimization approach is proposed to open the band gap at a prescribed frequency range and to further maximize the attenuation efficiency of the elastic wave at a specific frequency or within a prescribed frequency range. Numerical results demonstrate the effectiveness of the proposed gradient-based optimization method for enhancing the wave attenuation properties.展开更多
In recent years, the metro system has advanced into an efficient transport system and become the mainstay of urban passenger transport in many mega-cities. Passenger flow is the foundation of making and coordinating o...In recent years, the metro system has advanced into an efficient transport system and become the mainstay of urban passenger transport in many mega-cities. Passenger flow is the foundation of making and coordinating operation plans for the metro system, and therefore, a variety of studies were conducted on transit assignment models. Nevertheless route choice sets of passengers also play a paramount role in flow estimation and demand prediction. This paper first discusses the main route constraints of which the train schedule is the most important, that distinguish rail networks from road networks. Then, a two-step approach to generate route choice set in a metro network is proposed. Particu- larly, the improved approach introduces a route filtenng with train operational information based on the conventional method. An initial numerical test shows that the proposed approach gives more reasonable route choice sets for scheduled metro networks, and, consequently, obtains more accurate results from passenger flow assignment. Recommendations for possible opportunities to apply this approach to metro operations are also provided, including its integration into a metro passenger flow assignment and simulation system in practice to help metro authorities provide more precise guidance information for passengers to travel.展开更多
Controlled islanding is an important approach to prevent instability in power grids.In this paper,a novel approach is proposed for power system separation,which consists of two steps:1)Finding multiple islanding scena...Controlled islanding is an important approach to prevent instability in power grids.In this paper,a novel approach is proposed for power system separation,which consists of two steps:1)Finding multiple islanding scenarios;2)Choosing the best option to obtain the most desirable island.In the first step,different islanding solutions are determined by a proposed hierarchical clustering method.In this algorithm,which is based on a minimum active power flow disruption objective function,the generator coherency constraints are considered in the clustering process.In the second step,the best separation scenario is chosen based on an arbitrary objective function.Particularly,in this paper,the amount of load shedding and the voltage profile deviation after separation are considered as the final criteria to select the best solution among available options.In so doing,the degree of load importance is also taken into account.The proposed two-step method is applied on an IEEE 9-bus test system and it is also evaluated on an IEEE 39-bus grid.The simulation results on the IEEE 39-bus grid and the comparative analysis with a state-of-the-art method confirm that the final islanding solution is more optimized based on the secondary criteria,which have not been addressed in the existing approaches.Moreover,the proposed method is computationally efficient and can be employed in real-scale power grids.展开更多
文摘Annual arrhythmic sudden cardiac death ranges from 0.6%to 4%in ischemic cardiomyopathy(ICM),1%to 2%in non-ischemic cardiomyopathy(NICM),and 1%in hypertrophic cardiomyopathy(HCM).Towards a more effective arrhythmic risk stratification(ARS)we hereby present a two-step ARS with the usage of seven non-invasive risk factors:Late potentials presence(≥2/3 positive criteria),premature ventricular contractions(≥30/h),non-sustained ventricular tachycardia(≥1episode/24 h),abnormal heart rate turbulence(onset≥0%and slope≤2.5 ms)and reduced deceleration capacity(≤4.5 ms),abnormal T wave alternans(≥65μV),decreased heart rate variability(SDNN<70ms),and prolonged QT_(c)interval(>440 ms in males and>450 ms in females)which reflect the arrhythmogenic mechanisms for the selection of the intermediate arrhythmic risk patients in the first step.In the second step,these intermediate-risk patients undergo a programmed ventricular stimulation(PVS)for the detection of inducible,truly high-risk ICM and NICM patients,who will benefit from an implantable cardioverter defibrillator.For HCM patients,we also suggest the incorporation of the PVS either for the low HCM Risk-score patients or for the patients with one traditional risk factor in order to improve the inadequate sensitivity of the former and the low specificity of the latter.
基金Project (No. 02CDP036) supported by the Royal Netherlands Academy of Arts and Sciences (KNAW), the Netherlands
文摘For river basin management, the reliability of the rating curves mainly depends on the accuracy and time period of the observed discharge and water level data. In the Elbe decision support system (DSS), the rating curves are combined with the HEC-6 model to investigate the effects of river engineering measures on the Elbe River system. In such situations, the uncertainty originating from the HEC-6 model is of significant importance for the reliability of the rating curves and the corresponding DSS results. This paper proposes a two-step approach to analyze the uncertainty in the rating curves and propagate it into the Elbe DSS: analytic method and Latin Hypercube simulation. Via this approach the uncertainty and sensitivity of model outputs to input parameters are successfully investigated. The results show that the proposed approach is very efficient in investigating the effect of uncertainty and can play an important role in improving decision-making under uncertainty.
基金Project supported by the National Natural Science Foundation of China(Nos.11502043,11332004 and 11402046)the Fundamental Research Funds for the Central Universities Of China(DUT15ZD101)the 111 Project(B14013)
文摘Phononic materials with specific band-gap characteristics at desired frequency ranges are in great demand for vibration and noise isolation, elastic wave filters, and acoustic devices. The attenuation coefficient curve depicts both the frequency range of band gap and the attenuation of elastic wave, where the frequency ranges corresponding to the none-zero attenuation coefficients are band gaps. Therefore, the band-gap characteristics can be achieved through maximizing the attenuation coefficient at the corresponding frequency or within the corresponding frequency range. Because the attenuation coefficient curve is not smooth in the frequency domain, the gradient-based optimization methods cannot be directly used in the design optimization of phononic band-gap materials to achieve the maximum attenuation within the desired frequency range. To overcome this difficulty, the objective of maximizing the attenuation coefficient is transformed into maximizing its Cosine, and in this way, the objective function is smoothed and becomes differentiable. Based on this objective function, a novel gradient-based optimization approach is proposed to open the band gap at a prescribed frequency range and to further maximize the attenuation efficiency of the elastic wave at a specific frequency or within a prescribed frequency range. Numerical results demonstrate the effectiveness of the proposed gradient-based optimization method for enhancing the wave attenuation properties.
基金financially supported by the National Science and Technology Support Program of China(2011BAG01B01)Program for Young Excellent Talents at Tongji University (2014KJ015)+1 种基金Shanghai Philosophy and Social Science Funds (2015EGL006)Fundamental Research Funds for the Central Universities of China(1600219249)
文摘In recent years, the metro system has advanced into an efficient transport system and become the mainstay of urban passenger transport in many mega-cities. Passenger flow is the foundation of making and coordinating operation plans for the metro system, and therefore, a variety of studies were conducted on transit assignment models. Nevertheless route choice sets of passengers also play a paramount role in flow estimation and demand prediction. This paper first discusses the main route constraints of which the train schedule is the most important, that distinguish rail networks from road networks. Then, a two-step approach to generate route choice set in a metro network is proposed. Particu- larly, the improved approach introduces a route filtenng with train operational information based on the conventional method. An initial numerical test shows that the proposed approach gives more reasonable route choice sets for scheduled metro networks, and, consequently, obtains more accurate results from passenger flow assignment. Recommendations for possible opportunities to apply this approach to metro operations are also provided, including its integration into a metro passenger flow assignment and simulation system in practice to help metro authorities provide more precise guidance information for passengers to travel.
文摘Controlled islanding is an important approach to prevent instability in power grids.In this paper,a novel approach is proposed for power system separation,which consists of two steps:1)Finding multiple islanding scenarios;2)Choosing the best option to obtain the most desirable island.In the first step,different islanding solutions are determined by a proposed hierarchical clustering method.In this algorithm,which is based on a minimum active power flow disruption objective function,the generator coherency constraints are considered in the clustering process.In the second step,the best separation scenario is chosen based on an arbitrary objective function.Particularly,in this paper,the amount of load shedding and the voltage profile deviation after separation are considered as the final criteria to select the best solution among available options.In so doing,the degree of load importance is also taken into account.The proposed two-step method is applied on an IEEE 9-bus test system and it is also evaluated on an IEEE 39-bus grid.The simulation results on the IEEE 39-bus grid and the comparative analysis with a state-of-the-art method confirm that the final islanding solution is more optimized based on the secondary criteria,which have not been addressed in the existing approaches.Moreover,the proposed method is computationally efficient and can be employed in real-scale power grids.
