Determining an optimal sample size is a key step in designing field surveys,and is particularly important for detecting the spatial pattern of highly variable properties such as soil organic carbon(SOC).Based on 550 s...Determining an optimal sample size is a key step in designing field surveys,and is particularly important for detecting the spatial pattern of highly variable properties such as soil organic carbon(SOC).Based on 550 soil sampling points in the nearsurface layer(0 to 20 cm)in a representative region of northern China's agro-pastoral ecotone,we studied effects of four interpolation methods such as ordinary kriging(OK),universal kriging(UK),inverse distance weighting(IDW)and radial basis function(RBF)and random subsampling(50,100,200,300,400,and 500)on the prediction accuracy of SOC estimation.When the Shannon's Diversity Index(SHDI)and Shannon's Evenness Index(SHEI)was 2.01 and 0.67,the OK method appeared to be a superior method,which had the smallest root mean square error(RMSE)and the mean error(ME)nearest to zero.On the contrary,the UK method performed poorly for the interpolation of SOC in the present study.The sample size of 200 had the most accurate prediction;50 sampling points produced the worst prediction accuracy.Thus,we used 200 samples to estimate the study area's soil organic carbon density(SOCD)by the OK method.The total SOC storage to a depth of 20 cm in the study area was 117.94 Mt,and its mean SOCD was 2.40 kg/m2.The SOCD kg/(C⋅m2)of different land use types were in the following order:woodland(3.29)>grassland(2.35)>cropland(2.19)>sandy land(1.55).展开更多
The closed-loop wireless power transfer(WPT)system can realize constant voltage output in the presence of perturbation.However,the parameter design of the controller is a difficult problem.The traditional trial-and-er...The closed-loop wireless power transfer(WPT)system can realize constant voltage output in the presence of perturbation.However,the parameter design of the controller is a difficult problem.The traditional trial-and-error method is time-consuming and difficult to find optimal parameters.A parameter optimization strategy of control systems for uncertain WPT systems using the modified genetic algorithm(MGA)is proposed.Firstly,because the system has different characteristics at different periods,the simulation process is divided into three stages.The first one is the start-up stage,in which we mainly consider the overshoot and the rate of the voltage rise.The second one is the tracking stage,in which the tracking time and switching loss are mainly considered.The third one is the stabilisation stage,in which the steady-state error and switching loss are mainly considered.Secondly,three cost functions are designed according to the characteristics of the three stages,and then the optimal controller parameters of each stage are obtained by using MGA.Finally,the effectiveness of the proposed method is verified by simulation.The optimization results show that compared with the previous parameter optimization method,the optimal controller parameters obtained by the proposed method make the WPT system achieve better performance.展开更多
Acute basilar artery occlusion(BAO)may lead to severe disability or death in about 70%of patients.12 Previous studies have estab-lished endovascular treatment(EVT)as the standard treatment for patients with acute ante...Acute basilar artery occlusion(BAO)may lead to severe disability or death in about 70%of patients.12 Previous studies have estab-lished endovascular treatment(EVT)as the standard treatment for patients with acute anterior circulation occlusions.3-9 However,the ideal effective treatment for acute BAO remains controversial.展开更多
Background:With the recent publication of a large clinical trial on the use of a lower dose of intravenous(IV)tissue plasminogen activator(tPA)for acute ischaemic stroke(AIS),the concept of using a different dose has ...Background:With the recent publication of a large clinical trial on the use of a lower dose of intravenous(IV)tissue plasminogen activator(tPA)for acute ischaemic stroke(AIS),the concept of using a different dose has been debated.We intend to review the literature on using a lower dose of IV tPA and gain a better understanding of the impact of different IV doses on the treatment of patients with AIS.Methods:A comprehensive literature search of the related topics in PubMed,EMBASE,Web of Science and MEDLINE was carried out.Key words used include low dose IV tPA,thrombolysis,Alteplace and tPA for AIS.Findings were tabulated according to the size of the cohort studied,outcome,adverse event and level of evidence.The results of all studies using lower doses were analysed for efficacy and adverse events.Results:From 1992 to 2016,there were 23 trials that included 10950 patients published on the use of lower doses of IV tPA for AIS.Doses ranged from 0.5,0.6,0.75 to 0.85 mg/kg.Most were observational,retrospective and registry studies.One was a prospective open-label randomised controlled trial.13 trials combined lower doses of IV tPA with a glycoprotein IIb/IIIa inhibitor or thrombectomy.Patients treated with lower doses of IV tPA showed a trend of lower rate of symptomatic intracranial haemorrhage and mortality at 3 months but slightly more disability.Conclusions:Lower doses of IV tPA showed less haemorrhagic events but were not more effective compared with the standard dose.The optimal low dose of IV tPA remains unclear.Patients with AIS with a high risk of developing sypmtomatic intracranial haemorrhage might benefit from lower dose IV tPA,such as 0.6 mg/kg.展开更多
基金This research was supported by the National Key R and D Program of China(2016YFC0500901 and 2016YFC0500907)the National Natural Science Foundation of China(Grant Nos.31971466 and 41807525)the One Hundred Person Project of the Chinese Academy of Sciences(Y551821).
文摘Determining an optimal sample size is a key step in designing field surveys,and is particularly important for detecting the spatial pattern of highly variable properties such as soil organic carbon(SOC).Based on 550 soil sampling points in the nearsurface layer(0 to 20 cm)in a representative region of northern China's agro-pastoral ecotone,we studied effects of four interpolation methods such as ordinary kriging(OK),universal kriging(UK),inverse distance weighting(IDW)and radial basis function(RBF)and random subsampling(50,100,200,300,400,and 500)on the prediction accuracy of SOC estimation.When the Shannon's Diversity Index(SHDI)and Shannon's Evenness Index(SHEI)was 2.01 and 0.67,the OK method appeared to be a superior method,which had the smallest root mean square error(RMSE)and the mean error(ME)nearest to zero.On the contrary,the UK method performed poorly for the interpolation of SOC in the present study.The sample size of 200 had the most accurate prediction;50 sampling points produced the worst prediction accuracy.Thus,we used 200 samples to estimate the study area's soil organic carbon density(SOCD)by the OK method.The total SOC storage to a depth of 20 cm in the study area was 117.94 Mt,and its mean SOCD was 2.40 kg/m2.The SOCD kg/(C⋅m2)of different land use types were in the following order:woodland(3.29)>grassland(2.35)>cropland(2.19)>sandy land(1.55).
基金Startup Foundation for Introducing Talent of NUISTNational Natural Science Foundation of China,Grant/Award Number:62006124+1 种基金Nature Science Foundation of Jiangsu Province,Grant/Award Number:BK20200811Natural Science Foundation of the Jiangsu Higher Edu-cation Institutions of China,Grant/Award Number:20KJB520006。
文摘The closed-loop wireless power transfer(WPT)system can realize constant voltage output in the presence of perturbation.However,the parameter design of the controller is a difficult problem.The traditional trial-and-error method is time-consuming and difficult to find optimal parameters.A parameter optimization strategy of control systems for uncertain WPT systems using the modified genetic algorithm(MGA)is proposed.Firstly,because the system has different characteristics at different periods,the simulation process is divided into three stages.The first one is the start-up stage,in which we mainly consider the overshoot and the rate of the voltage rise.The second one is the tracking stage,in which the tracking time and switching loss are mainly considered.The third one is the stabilisation stage,in which the steady-state error and switching loss are mainly considered.Secondly,three cost functions are designed according to the characteristics of the three stages,and then the optimal controller parameters of each stage are obtained by using MGA.Finally,the effectiveness of the proposed method is verified by simulation.The optimization results show that compared with the previous parameter optimization method,the optimal controller parameters obtained by the proposed method make the WPT system achieve better performance.
文摘Acute basilar artery occlusion(BAO)may lead to severe disability or death in about 70%of patients.12 Previous studies have estab-lished endovascular treatment(EVT)as the standard treatment for patients with acute anterior circulation occlusions.3-9 However,the ideal effective treatment for acute BAO remains controversial.
基金QD was funded by National Nature Science of China(81571109)XC was funded by National Nature Science of China(81100861)Sponsored by Shanghai Rising-Star Program.
文摘Background:With the recent publication of a large clinical trial on the use of a lower dose of intravenous(IV)tissue plasminogen activator(tPA)for acute ischaemic stroke(AIS),the concept of using a different dose has been debated.We intend to review the literature on using a lower dose of IV tPA and gain a better understanding of the impact of different IV doses on the treatment of patients with AIS.Methods:A comprehensive literature search of the related topics in PubMed,EMBASE,Web of Science and MEDLINE was carried out.Key words used include low dose IV tPA,thrombolysis,Alteplace and tPA for AIS.Findings were tabulated according to the size of the cohort studied,outcome,adverse event and level of evidence.The results of all studies using lower doses were analysed for efficacy and adverse events.Results:From 1992 to 2016,there were 23 trials that included 10950 patients published on the use of lower doses of IV tPA for AIS.Doses ranged from 0.5,0.6,0.75 to 0.85 mg/kg.Most were observational,retrospective and registry studies.One was a prospective open-label randomised controlled trial.13 trials combined lower doses of IV tPA with a glycoprotein IIb/IIIa inhibitor or thrombectomy.Patients treated with lower doses of IV tPA showed a trend of lower rate of symptomatic intracranial haemorrhage and mortality at 3 months but slightly more disability.Conclusions:Lower doses of IV tPA showed less haemorrhagic events but were not more effective compared with the standard dose.The optimal low dose of IV tPA remains unclear.Patients with AIS with a high risk of developing sypmtomatic intracranial haemorrhage might benefit from lower dose IV tPA,such as 0.6 mg/kg.
