Petrochemical industry plays an important role in the development of the national economy. Purified terephthalic acid(PTA) is one of the most important intermediate raw materials in the petrochemical and chemical fibe...Petrochemical industry plays an important role in the development of the national economy. Purified terephthalic acid(PTA) is one of the most important intermediate raw materials in the petrochemical and chemical fiber industries. PTA production has two parts:p-xylene(PX) oxidation process and crude terephthalic acid(CTA) hydropurification process. The CTA hydropurification process is used to reduce impurities, such as 4-carboxybenzaldehyde, which is produced by a side reaction in the PX oxidation process and is harmful to the polyester industry. From the safety and economic viewpoints, monitoring this process is necessary. Four main faults of this process are analyzed in this study. The common process monitoring methods always use T^2 and SPE statistic as control limits. However, the traditional methods do not fully consider the economic viewpoint. In this study, a new economic control chart design method based on the differential evolution(DE) algorithm is developed. The DE algorithm transforms the economic control chart design problem to an optimization problem and is an excellent solution to such problem. Case studies of the main faults of the hydropurification process indicate that the proposed method can achieve minimum profit loss.This method is useful in economic control chart design and can provide guidance for the petrochemical industry.展开更多
Rahim and Banerjee [1] developed a general model for the optimal design of x-control charts. The model minimizes the expected cost per unit time. The heart of the model is a theorem that derives the expected total cos...Rahim and Banerjee [1] developed a general model for the optimal design of x-control charts. The model minimizes the expected cost per unit time. The heart of the model is a theorem that derives the expected total cost and the expected cycle length. In this paper an alternative simple proof for the theorem is provided based on mathematical induction.展开更多
As catchments become urbanized due to population growth the impervious surfaces created by buildings and pavements in the expense of permeable soil, depressions, and vegetation cause rainwater to flow rapidly over the...As catchments become urbanized due to population growth the impervious surfaces created by buildings and pavements in the expense of permeable soil, depressions, and vegetation cause rainwater to flow rapidly over the landscape. To mitigate the adverse impact of urbanization such as increased flooding and depleted groundwater recharge, around the world, several best management practices, in other words, green infrastructures have been practised, and soak-away rain garden is one of them. However, to have a rapid assessment of soak-away rain gardens on a range of potential hydrologic conditions (e.g., size of the soak-away rain garden, saturated hydraulic conductivity of the in-situ soil, and saturated hydraulic conductivity of the filter media), hydrologic design guidelines or design charts of soak-away rain gardens that are specific for local conditions are not currently available for many regions including Singapore. Thus, in this paper, with a design hyetograph of 3-month average rainfall intensities of Singapore, hydrologic design charts, especially, design charts on overflow volume (as a % of total runoff volume) of soak-away rain gardens are established for a range of potential hydrologic conditions by developing a mathematical model based on Richard’s equation using COMSOL Multiphysics, a finite element analysis and solver software package for various physics and engineering applications. These easy-to-use look-up hydrologic design charts will be of great utility for local managers in the design of soak-away rain gardens.展开更多
Minerals are now being extracted from deep mines due to drying up of resource in shallow ground.The need for suitable supports and ground control mechanisms for safe mining necessitates proper pillar design with filli...Minerals are now being extracted from deep mines due to drying up of resource in shallow ground.The need for suitable supports and ground control mechanisms for safe mining necessitates proper pillar design with filling technology.In addition,high horizontal stress may cause collapse of hanging wall and footwall rocks,hence designing of suitable crown pillars is absolutely necessary for imposing overall safety of the stopes.This paper provides a methodology for the evaluation of the required thickness of crown pillars for safe operation at depth ranging from 600 m to 1000 m.Analyses are conducted with the results of 108 non-linear numerical models considering Drucker-Prager material model in plane strain condition.Material properties of ore body rock and thickness of crown pillars are varied and safety factors of pillars estimated.Then,a generalized statistical relationship between the safety factors of crown pillars with the various input parameters is developed.The developed multivariate regression model is utilized for generating design/stability charts of pillars for different geo-mining conditions.These design charts can be used for the design of crown pillar thickness with the depth of the working,taking into account the changes of the rock mass conditions in underground metal mine.展开更多
The wave attenuation performance of a floating breakwater is important in engineering applications.On the basis of potential flow theory,the analytical and simplified solutions of the transmission coefficient of a flo...The wave attenuation performance of a floating breakwater is important in engineering applications.On the basis of potential flow theory,the analytical and simplified solutions of the transmission coefficient of a floating breakwater are deduced via velocity potential decompositions and eigenfunction expansions.The effects of the floating breakwater configuration,working sea state and motion response on the wave attenuation performance are described,facilitating a deeper investigation into the wave attenuation mechanism of the breakwater.The results indicate that the width and draft of the breakwater,incident wavelength,and motion response significantly affect the transmission coefficient of the breakwater.The wave passability rate,α1(α1=0.5−2B/L),is defined to qualitatively explain why long-period waves are difficult to control and attenuate.The radiation effect caused by the motion of the floating breakwater on the transmission coefficient is relatively complex,and the wave attenuation efficiency of the breakwater can be improved by optimizing the motion response.The incident wavelength and breakwater width are selected as the control parameters,and transmission coefficient charts of the floating breakwater for two-dimensional conditions are drawn,providing technical guidance for the configuration selection and design of the floating breakwater.展开更多
利用Weather tool工具中的焓湿图对佳木斯地区的气象数据进行分析,数据为CSWD(Chinese Standard Weather Data)。通过焓湿图的分析,确定出适合佳木斯地区的具体被动式设计策略,主要有被动式太阳能采暖、使用围护结构的蓄热材料和自然通...利用Weather tool工具中的焓湿图对佳木斯地区的气象数据进行分析,数据为CSWD(Chinese Standard Weather Data)。通过焓湿图的分析,确定出适合佳木斯地区的具体被动式设计策略,主要有被动式太阳能采暖、使用围护结构的蓄热材料和自然通风,为建筑师在建筑方案设计阶段提供有效的参考。展开更多
基金supported by the National Natural Science Foundation of China (61422303, 21376077)Fundamental Research Funds for Central Universities
文摘Petrochemical industry plays an important role in the development of the national economy. Purified terephthalic acid(PTA) is one of the most important intermediate raw materials in the petrochemical and chemical fiber industries. PTA production has two parts:p-xylene(PX) oxidation process and crude terephthalic acid(CTA) hydropurification process. The CTA hydropurification process is used to reduce impurities, such as 4-carboxybenzaldehyde, which is produced by a side reaction in the PX oxidation process and is harmful to the polyester industry. From the safety and economic viewpoints, monitoring this process is necessary. Four main faults of this process are analyzed in this study. The common process monitoring methods always use T^2 and SPE statistic as control limits. However, the traditional methods do not fully consider the economic viewpoint. In this study, a new economic control chart design method based on the differential evolution(DE) algorithm is developed. The DE algorithm transforms the economic control chart design problem to an optimization problem and is an excellent solution to such problem. Case studies of the main faults of the hydropurification process indicate that the proposed method can achieve minimum profit loss.This method is useful in economic control chart design and can provide guidance for the petrochemical industry.
文摘Rahim and Banerjee [1] developed a general model for the optimal design of x-control charts. The model minimizes the expected cost per unit time. The heart of the model is a theorem that derives the expected total cost and the expected cycle length. In this paper an alternative simple proof for the theorem is provided based on mathematical induction.
文摘As catchments become urbanized due to population growth the impervious surfaces created by buildings and pavements in the expense of permeable soil, depressions, and vegetation cause rainwater to flow rapidly over the landscape. To mitigate the adverse impact of urbanization such as increased flooding and depleted groundwater recharge, around the world, several best management practices, in other words, green infrastructures have been practised, and soak-away rain garden is one of them. However, to have a rapid assessment of soak-away rain gardens on a range of potential hydrologic conditions (e.g., size of the soak-away rain garden, saturated hydraulic conductivity of the in-situ soil, and saturated hydraulic conductivity of the filter media), hydrologic design guidelines or design charts of soak-away rain gardens that are specific for local conditions are not currently available for many regions including Singapore. Thus, in this paper, with a design hyetograph of 3-month average rainfall intensities of Singapore, hydrologic design charts, especially, design charts on overflow volume (as a % of total runoff volume) of soak-away rain gardens are established for a range of potential hydrologic conditions by developing a mathematical model based on Richard’s equation using COMSOL Multiphysics, a finite element analysis and solver software package for various physics and engineering applications. These easy-to-use look-up hydrologic design charts will be of great utility for local managers in the design of soak-away rain gardens.
文摘Minerals are now being extracted from deep mines due to drying up of resource in shallow ground.The need for suitable supports and ground control mechanisms for safe mining necessitates proper pillar design with filling technology.In addition,high horizontal stress may cause collapse of hanging wall and footwall rocks,hence designing of suitable crown pillars is absolutely necessary for imposing overall safety of the stopes.This paper provides a methodology for the evaluation of the required thickness of crown pillars for safe operation at depth ranging from 600 m to 1000 m.Analyses are conducted with the results of 108 non-linear numerical models considering Drucker-Prager material model in plane strain condition.Material properties of ore body rock and thickness of crown pillars are varied and safety factors of pillars estimated.Then,a generalized statistical relationship between the safety factors of crown pillars with the various input parameters is developed.The developed multivariate regression model is utilized for generating design/stability charts of pillars for different geo-mining conditions.These design charts can be used for the design of crown pillar thickness with the depth of the working,taking into account the changes of the rock mass conditions in underground metal mine.
基金supported by the China National Funds for Distinguished Young Scientists(Grant No.52025112)the National Natural Science Foundation of China(Grant Nos.52331011 and 52301322)the Jiangsu Provincial Natural Science Foundation(Grant No.BK20220653).
文摘The wave attenuation performance of a floating breakwater is important in engineering applications.On the basis of potential flow theory,the analytical and simplified solutions of the transmission coefficient of a floating breakwater are deduced via velocity potential decompositions and eigenfunction expansions.The effects of the floating breakwater configuration,working sea state and motion response on the wave attenuation performance are described,facilitating a deeper investigation into the wave attenuation mechanism of the breakwater.The results indicate that the width and draft of the breakwater,incident wavelength,and motion response significantly affect the transmission coefficient of the breakwater.The wave passability rate,α1(α1=0.5−2B/L),is defined to qualitatively explain why long-period waves are difficult to control and attenuate.The radiation effect caused by the motion of the floating breakwater on the transmission coefficient is relatively complex,and the wave attenuation efficiency of the breakwater can be improved by optimizing the motion response.The incident wavelength and breakwater width are selected as the control parameters,and transmission coefficient charts of the floating breakwater for two-dimensional conditions are drawn,providing technical guidance for the configuration selection and design of the floating breakwater.
文摘利用Weather tool工具中的焓湿图对佳木斯地区的气象数据进行分析,数据为CSWD(Chinese Standard Weather Data)。通过焓湿图的分析,确定出适合佳木斯地区的具体被动式设计策略,主要有被动式太阳能采暖、使用围护结构的蓄热材料和自然通风,为建筑师在建筑方案设计阶段提供有效的参考。
