Short-duration heavy rainfall(SHR),as delineated by the National Meteorological Center of the China Me-teorological Administration,is characterized by hourly rainfall amounts no less than 20.0 mm.SHR is one of the mos...Short-duration heavy rainfall(SHR),as delineated by the National Meteorological Center of the China Me-teorological Administration,is characterized by hourly rainfall amounts no less than 20.0 mm.SHR is one of the most common convective weather phenomena that can cause severe damage.Short-range forecasting of SHR is an important part of operational severe weather prediction.In the present study,an improved objective SHR forecasting scheme was developed by adopting the ingredients-based methodology and using the fuzzy logic approach.The 1.0°×1.0°National Centers for Environmental Prediction(NCEP)final analysis data and the ordinary rainfall(0.1-19.9 mm h-1)and SHR observational data from 411 stations were used in the improved scheme.The best lifted index,the total precipitable water,the 925 hPa specific humidity(Q 925),and the 925 hPa divergence(DIV 925)were selected as predictors based on objective analysis.Continuously distributed membership functions of predictors were obtained based on relative frequency analysis.The weights of predictors were also objectively determined.Experiments with a typhoon SHR case and a spring SHR case show that the main possible areas could be captured by the improved scheme.Verification of SHR forecasts within 96 hours with NCEP global forecasts 1.0°×1.0°data initiated at 08:00 Beijing Time during the warm seasons in 2015 show the results were improved from both deterministic and probabilistic perspectives.This study provides an objectively feasible choice for short-range guidance forecasts of SHR.The scheme can be applied to other convective phenomena.展开更多
In this paper, an improved splitting method, based on the completely square-conservative explicit difference schemes, is established. Not only can the time-direction precision of this method be higher than that of the...In this paper, an improved splitting method, based on the completely square-conservative explicit difference schemes, is established. Not only can the time-direction precision of this method be higher than that of the traditional splitting methods but also can the physical feature of mutual dependence of the fast and the slow stages that are calculated separately and splittingly be kept as well. Moreover, the method owns an universality, it can be generalized to other square-conservative difference schemes, such as the implicit and complete ones and the explicit and instantaneous ones. Good time benefits can be acquired when it is applied in the numerical simulations of the monthly mean currents of the South China Sea.展开更多
Soils with strain-softening behavior — manifesting as a reduction of strength with increasing plastic strain — are commonly found in the natural environment. For slopes in these soils,a progressive failure mechanism...Soils with strain-softening behavior — manifesting as a reduction of strength with increasing plastic strain — are commonly found in the natural environment. For slopes in these soils,a progressive failure mechanism can occur due to a reduction of strength with increasing strain. Finite element method based numerical approaches have been widely performed for simulating such failure mechanism,owning to their ability for tracing the formation and development of the localized shear strain. However,the reliability of the currently used approaches are often affected by poor convergence or significant mesh-dependency,and their applicability is limited by the use of complicated soil models. This paper aims to overcome these limitations by developing a finite element approach using a local arc-length controlled iterative algorithm as the solution strategy. In the proposed finite element approach,the soils are simulated with an elastoplastic constitutive model in conjunction with the Mohr-Coulomb yield function. The strain-softening behavior is represented by a piece-wise linearrelationship between the Mohr-Coulomb strength parameters and the deviatoric plastic strain. To assess the reliability of the proposed finite element approach,comparisons of the numerical solutions obtained by different finite element methods and meshes with various qualities are presented. Moreover,a landslide triggered by excavation in a real expressway construction project is analyzed by the presented finite element approach to demonstrate its applicability for practical engineering problems.展开更多
Background: The Occupational Safety and Health Council(OSHC) is committed to improve the safety performance of the high risk construction industry.In the past three years,about 40% of the fatal accidents in the constr...Background: The Occupational Safety and Health Council(OSHC) is committed to improve the safety performance of the high risk construction industry.In the past three years,about 40% of the fatal accidents in the construction industry were related to Renovation,Maintenance,Alteration and Addition(RMAA).Due to the poor safety record,some of the RMAA contractors have difficulty in obtaining the Employees' Compensation Insurance(ECI) cover in the market,or if they could obtain the ECI,the premium rate would be exceedingly high.In view of this,the OSHC,the Labour Department jointly launched"OSH Star Enterprise-Pilot Scheme on Safety Accreditation for the RMAA Industry",which prompts the industry to take practicable safety measures to improve the safety of working environment and reduce occupational injuries.The program also helps the stakeholders and insurers to identify safety-conscious contractors and thereby provide them with a favourable premium rate under the Employees' Compensation Insurance Residual Scheme(ECIRS).Objectives: The OSHC launches the Pilot Scheme to improve the safety performance of the RMAA industry through providing safety training,subsidizing enterprise to purchase safety equipment and providing safety audit.We also use financial incentive to encourage RMAA enterprises to join the Pilot Scheme-for those who are accredited as "OSH Star Enterprise"could receive a premium discount from the ERIRS when obtaining the ECI.The scheme also differentiates those safety-conscious and law-abiding enterprises from the poor performers,which helps the industry and public identifying the RMAA contractors who pay attention to work safety.Methods: The Pilot Scheme targets RMAA enterprises that employ less than 50 employees in Hong Kong.A three-pronged approach is used to improve the safety performance of the RMAA industry: the Pilot Scheme provides(1) financial support for the RMAA contractors to buy a transportable temporary anchor device and full body safety harness and its anchor system;(2) safety training on RMAA work safety and safety & health supervisor course;and(3) safety audit.Results: Enterprises that successfully pass the safety audit and satisfied the Scheme requirements will be accredited as"OSH Star Enterprise",which will be valid for two years.These enterprises can also be upgraded to"OSH Gold Star Enterprise"based on their continuous improvement in safety performance.OSHC will set up a register of OSH-accredited enterprises in RMAA works for reference of the public to facilitate their choosing of accredited contractors.The Employees' Compensation Insurance Residual Scheme Bureau will provide privileged premium rate for enterprises with OSH accreditation."OSH Star Enterprise"could enjoy 40% discounts when joining their insurance scheme.For example,a skilled worker's annual premium can be reduced by about HK $ 36,000.While,the "OSH Gold Star Enterprise"could enjoy 50% discounts when joining their insurance scheme,which means a skilled worker's annual premium can be reduced up to HK $ 45,000.Achievements: This Pilot Scheme offers practical assistance as well as attractive financial incentives for the RMAA industry to improve their safety performance.The Employees'Compensation Insurance Residual Scheme provides premium discounts for enterprises that have a good safety record.It provides incentive for RMAA contractors to actively participate in the Pilot Scheme.The Scheme demonstrates that by providing a safe working environment and appropriate personal protective equipment to workers,the enterprise not only helps to reduce the accident rate of the industry but also receive an economic return.The Pilot Scheme bridges stakeholders of RMAA industry,the government and the insurance industry creating an "all-win"situation.This partnership approach to prevent injuries and accidents in the construction industry could be an effective model for other industries.展开更多
This paper reviews the summary and analysis of special technical safety schemes for hazardous and ultrahazardous activities,supported by housing scaffolding,installation,and dismantling of outer wall attached tower cr...This paper reviews the summary and analysis of special technical safety schemes for hazardous and ultrahazardous activities,supported by housing scaffolding,installation,and dismantling of outer wall attached tower crane,deep foundation pit with supporting structure,municipal bridge box girder formwork support,as well as grooved Larsen steel sheet pile,which are commonly seen in recent years,so as to enhance the pertinence,rationality,and economy of the special program to strengthen safety.展开更多
为合理地解决环境敏感区铁路线路方案综合优选问题,研究顾及环境敏感特征的铁路线路方案优选方法 .首先,基于文献调研和环境敏感区特征探析,分析总结影响线路方案的因素,构建涵盖4大方面18项指标的顾及环境敏感特征的铁路线路方案优选...为合理地解决环境敏感区铁路线路方案综合优选问题,研究顾及环境敏感特征的铁路线路方案优选方法 .首先,基于文献调研和环境敏感区特征探析,分析总结影响线路方案的因素,构建涵盖4大方面18项指标的顾及环境敏感特征的铁路线路方案优选指标体系.其次,在专家经验主观赋权和工程信息客观赋权的基础上,运用灰色关联分析理论进行组合赋权.然后,结合改进优劣解距离法(Technique for Order Preference by Similarity to an Ideal Solution, TOPSIS)确定各线路方案的相对贴近度,进而实现线路方案优选.最后,以新建铁路西宁至成都线合作至郎木寺段线路方案选择为例进行优选方法验证.研究结果表明:该区段线路的4个备选方案的相对贴近度依次为0.527 9,0.523 6,0.508 7,0.522 7,方案一的相对贴近度最大为最优方案,基于本方法的优选结果与实际专家论证结果一致;与传统TOPSIS比较,基于改进TOPSIS的运算结果避免了计算结果受单方面优势指标影响的弊端,在运算过程中将线路方案涉及的极端优劣指标进行综合权衡考量,得到的运算结果更贴近实际情况.研究成果可为未来环境敏感区线路方案优选问题提供一种新的优选思路.展开更多
为提高山区隧道施工场地布置方案决策的准确性,以牛栾村隧道六种施工场地布置方案为例,提出了基于改进灰靶的方案优选模型。首先,通过分析场地布置方案影响因素,构建了以方案可行性、方案经济性、环境影响和社会效益影响为核心的评价指...为提高山区隧道施工场地布置方案决策的准确性,以牛栾村隧道六种施工场地布置方案为例,提出了基于改进灰靶的方案优选模型。首先,通过分析场地布置方案影响因素,构建了以方案可行性、方案经济性、环境影响和社会效益影响为核心的评价指标体系;其次,采用云模型将定性指标定量描述,并运用CRITIC(criteria importance though intercriteria correlation)确定指标权重;最后以灰色关联差异信息值为基础,结合欧几里得理论计算修正的加权靶心距,通过对比靶心距实现方案优选,并采用单因素轮换法(one-at-a-time,OAT)进行了指标敏感性分析。结果表明:最优方案的加权靶心距为0.610,评选出的方案与实际一致,并分析出“地形地貌改变”为对方案评选影响最大的指标。可见,该方法呈现了各方案的优劣,使山区隧道施工场地布置方案评选更科学、合理。展开更多
基金Key R&D Program of Xizang Autonomous Region(XZ202101ZY0004G)National Natural Science Foundation of China(U2142202)+1 种基金National Key R&D Program of China(2022YFC3004104)Key Innovation Team of China Meteor-ological Administration(CMA2022ZD07)。
文摘Short-duration heavy rainfall(SHR),as delineated by the National Meteorological Center of the China Me-teorological Administration,is characterized by hourly rainfall amounts no less than 20.0 mm.SHR is one of the most common convective weather phenomena that can cause severe damage.Short-range forecasting of SHR is an important part of operational severe weather prediction.In the present study,an improved objective SHR forecasting scheme was developed by adopting the ingredients-based methodology and using the fuzzy logic approach.The 1.0°×1.0°National Centers for Environmental Prediction(NCEP)final analysis data and the ordinary rainfall(0.1-19.9 mm h-1)and SHR observational data from 411 stations were used in the improved scheme.The best lifted index,the total precipitable water,the 925 hPa specific humidity(Q 925),and the 925 hPa divergence(DIV 925)were selected as predictors based on objective analysis.Continuously distributed membership functions of predictors were obtained based on relative frequency analysis.The weights of predictors were also objectively determined.Experiments with a typhoon SHR case and a spring SHR case show that the main possible areas could be captured by the improved scheme.Verification of SHR forecasts within 96 hours with NCEP global forecasts 1.0°×1.0°data initiated at 08:00 Beijing Time during the warm seasons in 2015 show the results were improved from both deterministic and probabilistic perspectives.This study provides an objectively feasible choice for short-range guidance forecasts of SHR.The scheme can be applied to other convective phenomena.
基金Partly supported by the State Major Key Project for Basic Researches
文摘In this paper, an improved splitting method, based on the completely square-conservative explicit difference schemes, is established. Not only can the time-direction precision of this method be higher than that of the traditional splitting methods but also can the physical feature of mutual dependence of the fast and the slow stages that are calculated separately and splittingly be kept as well. Moreover, the method owns an universality, it can be generalized to other square-conservative difference schemes, such as the implicit and complete ones and the explicit and instantaneous ones. Good time benefits can be acquired when it is applied in the numerical simulations of the monthly mean currents of the South China Sea.
基金funded by the Chinese National Basic Research Program (2010CB731503)
文摘Soils with strain-softening behavior — manifesting as a reduction of strength with increasing plastic strain — are commonly found in the natural environment. For slopes in these soils,a progressive failure mechanism can occur due to a reduction of strength with increasing strain. Finite element method based numerical approaches have been widely performed for simulating such failure mechanism,owning to their ability for tracing the formation and development of the localized shear strain. However,the reliability of the currently used approaches are often affected by poor convergence or significant mesh-dependency,and their applicability is limited by the use of complicated soil models. This paper aims to overcome these limitations by developing a finite element approach using a local arc-length controlled iterative algorithm as the solution strategy. In the proposed finite element approach,the soils are simulated with an elastoplastic constitutive model in conjunction with the Mohr-Coulomb yield function. The strain-softening behavior is represented by a piece-wise linearrelationship between the Mohr-Coulomb strength parameters and the deviatoric plastic strain. To assess the reliability of the proposed finite element approach,comparisons of the numerical solutions obtained by different finite element methods and meshes with various qualities are presented. Moreover,a landslide triggered by excavation in a real expressway construction project is analyzed by the presented finite element approach to demonstrate its applicability for practical engineering problems.
文摘Background: The Occupational Safety and Health Council(OSHC) is committed to improve the safety performance of the high risk construction industry.In the past three years,about 40% of the fatal accidents in the construction industry were related to Renovation,Maintenance,Alteration and Addition(RMAA).Due to the poor safety record,some of the RMAA contractors have difficulty in obtaining the Employees' Compensation Insurance(ECI) cover in the market,or if they could obtain the ECI,the premium rate would be exceedingly high.In view of this,the OSHC,the Labour Department jointly launched"OSH Star Enterprise-Pilot Scheme on Safety Accreditation for the RMAA Industry",which prompts the industry to take practicable safety measures to improve the safety of working environment and reduce occupational injuries.The program also helps the stakeholders and insurers to identify safety-conscious contractors and thereby provide them with a favourable premium rate under the Employees' Compensation Insurance Residual Scheme(ECIRS).Objectives: The OSHC launches the Pilot Scheme to improve the safety performance of the RMAA industry through providing safety training,subsidizing enterprise to purchase safety equipment and providing safety audit.We also use financial incentive to encourage RMAA enterprises to join the Pilot Scheme-for those who are accredited as "OSH Star Enterprise"could receive a premium discount from the ERIRS when obtaining the ECI.The scheme also differentiates those safety-conscious and law-abiding enterprises from the poor performers,which helps the industry and public identifying the RMAA contractors who pay attention to work safety.Methods: The Pilot Scheme targets RMAA enterprises that employ less than 50 employees in Hong Kong.A three-pronged approach is used to improve the safety performance of the RMAA industry: the Pilot Scheme provides(1) financial support for the RMAA contractors to buy a transportable temporary anchor device and full body safety harness and its anchor system;(2) safety training on RMAA work safety and safety & health supervisor course;and(3) safety audit.Results: Enterprises that successfully pass the safety audit and satisfied the Scheme requirements will be accredited as"OSH Star Enterprise",which will be valid for two years.These enterprises can also be upgraded to"OSH Gold Star Enterprise"based on their continuous improvement in safety performance.OSHC will set up a register of OSH-accredited enterprises in RMAA works for reference of the public to facilitate their choosing of accredited contractors.The Employees' Compensation Insurance Residual Scheme Bureau will provide privileged premium rate for enterprises with OSH accreditation."OSH Star Enterprise"could enjoy 40% discounts when joining their insurance scheme.For example,a skilled worker's annual premium can be reduced by about HK $ 36,000.While,the "OSH Gold Star Enterprise"could enjoy 50% discounts when joining their insurance scheme,which means a skilled worker's annual premium can be reduced up to HK $ 45,000.Achievements: This Pilot Scheme offers practical assistance as well as attractive financial incentives for the RMAA industry to improve their safety performance.The Employees'Compensation Insurance Residual Scheme provides premium discounts for enterprises that have a good safety record.It provides incentive for RMAA contractors to actively participate in the Pilot Scheme.The Scheme demonstrates that by providing a safe working environment and appropriate personal protective equipment to workers,the enterprise not only helps to reduce the accident rate of the industry but also receive an economic return.The Pilot Scheme bridges stakeholders of RMAA industry,the government and the insurance industry creating an "all-win"situation.This partnership approach to prevent injuries and accidents in the construction industry could be an effective model for other industries.
文摘This paper reviews the summary and analysis of special technical safety schemes for hazardous and ultrahazardous activities,supported by housing scaffolding,installation,and dismantling of outer wall attached tower crane,deep foundation pit with supporting structure,municipal bridge box girder formwork support,as well as grooved Larsen steel sheet pile,which are commonly seen in recent years,so as to enhance the pertinence,rationality,and economy of the special program to strengthen safety.
文摘为合理地解决环境敏感区铁路线路方案综合优选问题,研究顾及环境敏感特征的铁路线路方案优选方法 .首先,基于文献调研和环境敏感区特征探析,分析总结影响线路方案的因素,构建涵盖4大方面18项指标的顾及环境敏感特征的铁路线路方案优选指标体系.其次,在专家经验主观赋权和工程信息客观赋权的基础上,运用灰色关联分析理论进行组合赋权.然后,结合改进优劣解距离法(Technique for Order Preference by Similarity to an Ideal Solution, TOPSIS)确定各线路方案的相对贴近度,进而实现线路方案优选.最后,以新建铁路西宁至成都线合作至郎木寺段线路方案选择为例进行优选方法验证.研究结果表明:该区段线路的4个备选方案的相对贴近度依次为0.527 9,0.523 6,0.508 7,0.522 7,方案一的相对贴近度最大为最优方案,基于本方法的优选结果与实际专家论证结果一致;与传统TOPSIS比较,基于改进TOPSIS的运算结果避免了计算结果受单方面优势指标影响的弊端,在运算过程中将线路方案涉及的极端优劣指标进行综合权衡考量,得到的运算结果更贴近实际情况.研究成果可为未来环境敏感区线路方案优选问题提供一种新的优选思路.
文摘为提高山区隧道施工场地布置方案决策的准确性,以牛栾村隧道六种施工场地布置方案为例,提出了基于改进灰靶的方案优选模型。首先,通过分析场地布置方案影响因素,构建了以方案可行性、方案经济性、环境影响和社会效益影响为核心的评价指标体系;其次,采用云模型将定性指标定量描述,并运用CRITIC(criteria importance though intercriteria correlation)确定指标权重;最后以灰色关联差异信息值为基础,结合欧几里得理论计算修正的加权靶心距,通过对比靶心距实现方案优选,并采用单因素轮换法(one-at-a-time,OAT)进行了指标敏感性分析。结果表明:最优方案的加权靶心距为0.610,评选出的方案与实际一致,并分析出“地形地貌改变”为对方案评选影响最大的指标。可见,该方法呈现了各方案的优劣,使山区隧道施工场地布置方案评选更科学、合理。