Vertical drains are used to accelerate consolidation of clays in ground improvement projects.Smear zones exist around these drains,where permeability is reduced due to soil disturbance caused by the installation proce...Vertical drains are used to accelerate consolidation of clays in ground improvement projects.Smear zones exist around these drains,where permeability is reduced due to soil disturbance caused by the installation process.Hansbo solution is widely used in practice to consider the effects of drain discharge capacity and smear on the consolidation process.In this study,a computationally efficient diameter reduction method(DRM)obtained from the Hansbo solution is proposed to consider the smear effect without the need to model the smear zone physically.Validated by analytical and numerical results,a diameter reduction factor is analytically derived to reduce the diameter of the drain,while achieving similar solutions of pore pressure dissipation profile as the classical full model of the smear zone and drain.With the DRM,the excess pore pressure u obtained from the reduced drain in the original un-disturbed soil zone is accurate enough for practical applications in numerical models.Such performance of DRM is independent of soil material property.Results also show equally accurate performance of DRM under conditions of multi-layered soils and coupled radial-vertical groundwater flow.展开更多
Objective:To evaluate the efficacy and side effects of praziquantel(PZQ) in the treatment of schistosomiasis in Ethiopia.Methods:In a cross-sectional study,stool specimens were collected from randomly selected 299 sch...Objective:To evaluate the efficacy and side effects of praziquantel(PZQ) in the treatment of schistosomiasis in Ethiopia.Methods:In a cross-sectional study,stool specimens were collected from randomly selected 299 school children in Shesha Kekele Elementary School,Wondo Genet, Southern Ethiopia,in April 2010.Stool specimens were examined using a single Kato-Katz thick smear for Schistosoma mansoni(5.mansoni) ova.Children who were found positive for S.mansoni were treated with a single oral dose of PZQ at 40 mg/kg bw and interviewed for treatment-related symptoms 24 hours after drug administration.Four weeks post-treatment,stool specimens were collected from the same children and examined following the same procedure as in the pretreatment.Drug efficacy was determined based on cure and egg reduction rates.Results:Pretreatment prevalence of S.mansoni infection was 74.9%with geometric mean egg count of 268. The evaluated generic PZQ produced an overall cure rate of 73.6%(P<0.000 1,OR:8.33,CI:5.3-13.1) and egg reduction rate of 68.2%(P=0.03,F=0.64).The cure rate showed significant association with age(x^2=H,P=0.004),the highest rate being observed in the 15-22 age group.83%of S. mansoni infected children showed various treatment-related symptoms,the most frerjiient being headache,nausea,and abdominal pain.These symptoms were associated with age(P<0.001) and pre-treatment intensity of infection(P<0.05).Conclusions:The present observations revealed relatively lower cure and egg reduction rates of the PZQ evaluated as compared to previous reports for other PZQ brands in Ethiopia.Hence,in depth studies are recommended to clarify whether the present relatively lower cure rate is the actual cure rate of the praziquantel evaluated,treatment failure,or reduced susceptibility of the parasite.Treatment-related side effects observed were transient and tolerable.展开更多
为了实现对星空观测图像中高亮目标产生的拖尾现象进行自动消除,建立了目标拖尾自动消除系统,对该系统所采用的图像背景高斯噪声分布参数估计、目标拖尾检测以及图像灰度值校正等算法进行研究。利用直方图最小二乘曲线拟合估计星空观测...为了实现对星空观测图像中高亮目标产生的拖尾现象进行自动消除,建立了目标拖尾自动消除系统,对该系统所采用的图像背景高斯噪声分布参数估计、目标拖尾检测以及图像灰度值校正等算法进行研究。利用直方图最小二乘曲线拟合估计星空观测图像背景高斯噪声的分布参数;利用观测图像中目标拖尾现象的特征提出一种基于统计信息的拖尾检测算法;在确定目标拖尾位置的基础上对被污染的像素进行灰度值校正;利用Visual Studio 2005开发出一套星空观测图像目标拖尾自动消除系统。实验结果表明:针对16bit,1 024×1 024的星空观测图像,单帧图像处理时间约为300ms,拖尾现象得到消除,恒星和目标等有用信息未被破坏。本文算法基本满足后续观测图像中弱小目标检测稳定、可靠、精度高等要求。展开更多
基金The authors wish to acknowledge the generous financial sup-port from the Singapore Maritime Institute(SMI)for this research within the project‘Evaluation of In-situ Consolidation of Dredged and Excavated Materials at Reclaimed Next Generation Tuas Port’(Project ID:SMI-2018-MA-01).
文摘Vertical drains are used to accelerate consolidation of clays in ground improvement projects.Smear zones exist around these drains,where permeability is reduced due to soil disturbance caused by the installation process.Hansbo solution is widely used in practice to consider the effects of drain discharge capacity and smear on the consolidation process.In this study,a computationally efficient diameter reduction method(DRM)obtained from the Hansbo solution is proposed to consider the smear effect without the need to model the smear zone physically.Validated by analytical and numerical results,a diameter reduction factor is analytically derived to reduce the diameter of the drain,while achieving similar solutions of pore pressure dissipation profile as the classical full model of the smear zone and drain.With the DRM,the excess pore pressure u obtained from the reduced drain in the original un-disturbed soil zone is accurate enough for practical applications in numerical models.Such performance of DRM is independent of soil material property.Results also show equally accurate performance of DRM under conditions of multi-layered soils and coupled radial-vertical groundwater flow.
基金financially supported by the Vice President Officefor Research and Dean of School of Graduate Studies and Aklilu Lemma Institute of Pathobiology(grant No.RDP/PY-014/09)
文摘Objective:To evaluate the efficacy and side effects of praziquantel(PZQ) in the treatment of schistosomiasis in Ethiopia.Methods:In a cross-sectional study,stool specimens were collected from randomly selected 299 school children in Shesha Kekele Elementary School,Wondo Genet, Southern Ethiopia,in April 2010.Stool specimens were examined using a single Kato-Katz thick smear for Schistosoma mansoni(5.mansoni) ova.Children who were found positive for S.mansoni were treated with a single oral dose of PZQ at 40 mg/kg bw and interviewed for treatment-related symptoms 24 hours after drug administration.Four weeks post-treatment,stool specimens were collected from the same children and examined following the same procedure as in the pretreatment.Drug efficacy was determined based on cure and egg reduction rates.Results:Pretreatment prevalence of S.mansoni infection was 74.9%with geometric mean egg count of 268. The evaluated generic PZQ produced an overall cure rate of 73.6%(P<0.000 1,OR:8.33,CI:5.3-13.1) and egg reduction rate of 68.2%(P=0.03,F=0.64).The cure rate showed significant association with age(x^2=H,P=0.004),the highest rate being observed in the 15-22 age group.83%of S. mansoni infected children showed various treatment-related symptoms,the most frerjiient being headache,nausea,and abdominal pain.These symptoms were associated with age(P<0.001) and pre-treatment intensity of infection(P<0.05).Conclusions:The present observations revealed relatively lower cure and egg reduction rates of the PZQ evaluated as compared to previous reports for other PZQ brands in Ethiopia.Hence,in depth studies are recommended to clarify whether the present relatively lower cure rate is the actual cure rate of the praziquantel evaluated,treatment failure,or reduced susceptibility of the parasite.Treatment-related side effects observed were transient and tolerable.
文摘为了实现对星空观测图像中高亮目标产生的拖尾现象进行自动消除,建立了目标拖尾自动消除系统,对该系统所采用的图像背景高斯噪声分布参数估计、目标拖尾检测以及图像灰度值校正等算法进行研究。利用直方图最小二乘曲线拟合估计星空观测图像背景高斯噪声的分布参数;利用观测图像中目标拖尾现象的特征提出一种基于统计信息的拖尾检测算法;在确定目标拖尾位置的基础上对被污染的像素进行灰度值校正;利用Visual Studio 2005开发出一套星空观测图像目标拖尾自动消除系统。实验结果表明:针对16bit,1 024×1 024的星空观测图像,单帧图像处理时间约为300ms,拖尾现象得到消除,恒星和目标等有用信息未被破坏。本文算法基本满足后续观测图像中弱小目标检测稳定、可靠、精度高等要求。
