Phosphorus is one of the most important nutrients required to support various kinds of biodegradation processes. As this particular nutrient is not included in the activated sludge model no. 1 （ASM1）, this study ext...Phosphorus is one of the most important nutrients required to support various kinds of biodegradation processes. As this particular nutrient is not included in the activated sludge model no. 1 （ASM1）, this study extended this model in order to determine the fate of phosphorus during the biodegradation processes. When some of the kinetics parameters are modified using observed data from the restoration project of the Xuxi River in Wuxi City, China, from August 25 to 31 in 2009, the extended model shows excellent results. In order to obtain optimum values of coefficients of nitrogen and phosphorus, the mass fraction method was used to ensure that the final results were reasonable and practically relevant. The temporal distribution of the data calculated with the extended ASM1 approximates that of the observed data.展开更多
Rice is the staple food of more than half of the world’s Population.The production,processing and management of paddy rice have provided the basic conditions for the living of mankind.The production of rice has not o...Rice is the staple food of more than half of the world’s Population.The production,processing and management of paddy rice have provided the basic conditions for the living of mankind.The production of rice has not only created展开更多
Relaxed Stable Stability （RSS） in an important part of the active control technology. It is a new way to raise the flying speed, distance and maneuverability of missile. Depth study of RSS technology plays an import...Relaxed Stable Stability （RSS） in an important part of the active control technology. It is a new way to raise the flying speed, distance and maneuverability of missile. Depth study of RSS technology plays an important role for the new concept missile design. This paper describes the detailed definition of RSS and its advantages, pres- ents the research status and prospects for its application in the design of new missiles.展开更多
Industrial solid waste(ISW)-cement blends have the advantages of low carbon,low energy consumption,and low pollution,but their clinker replacement level in low carbon cement is generally low.To address this challenge,...Industrial solid waste(ISW)-cement blends have the advantages of low carbon,low energy consumption,and low pollution,but their clinker replacement level in low carbon cement is generally low.To address this challenge,this study considers the latest progress and development trends in the ISW-cement blend research,focusing on the activation of ISWs,the formation of ISW-cement blends,and their associated hydration mechanisms.After the mechanical activation of ISWs,the D50(average size)typically drops below 10μm,and the specific surface area increases above 350 m2/kg.Thermal activation can increase the glassy-phase content and reactivity of ISWs,where the coal gangue activation temperature is usually set at 400-1000°C.Furthermore,the roles of ISWs in the hydration of ISW-cement blends are divided into physical and chemical roles.The physical action of ISWs usually acts in the early stage of the hydration of ISW-cement blends.Subsequently,ISWs participate in the hydration reaction of ISW-cement blends to generate products,such as C-(A)-S-H gels.Moreover,alkali activation affects the hydration kinetics of ISW-cement blends and modifies the proportion of gels.Environmental impacts and costs of ISW-cement blends have also been discussed to guide stakeholders in selecting sustainable ISWs.展开更多
A bench-scale cyclic activated sludge technology （CAST） was operated to study the biological phosphorus removal performance and a series of batch tests was carried out to demonstrate the accumulation of denitrifying...A bench-scale cyclic activated sludge technology （CAST） was operated to study the biological phosphorus removal performance and a series of batch tests was carried out to demonstrate the accumulation of denitrifying polyphosphate-accumulating organisms （DNPAOs） in CAST system. Under all operating conditions, step-feed CAST with enough carbon sources in influent had the highest nitrogen and phosphorus removal efficiency as well as good sludge settling performance. The average removal rate of COD, NH4^＋-N, PO4^3--P and total nitrogen （TN） was 88.2%, 98.7%, 97.5% and 92.1%, respectively. The average sludge volume index （SVI） was 133 mL/g. The optimum anaerobic/aerobic/anoxic （AOA） conditions for the cultivation of DNPAOs could be achieved by alternating anoxic/oxic operational strategy, thus a significant denitrifying phosphorus removal occurred in step-feed CAST. The denitrification of NO^x--N completed quickly due to step-feed operation and enough carbon sources, which could enhance phosphorus release and further phosphorus uptake capability of the system. Batch tests also proved that polyphosphate-accumulating organisms （PAOs） in the step-feed process had strong denitrifying phosphorus removal capacity. Both nitrate and nitrite could be used as electron acceptors in denitrifying phosphorus removal. Low COD supply with step-feed operation strategy would favor DNPAOs accumulation.展开更多
A bench-scale reactor（72 L） red with domestic sewage, was operated more than 3 months with three operation modes： traditional mode, modified mode and real-time control mode, so as to evaluate effects of the operati...A bench-scale reactor（72 L） red with domestic sewage, was operated more than 3 months with three operation modes： traditional mode, modified mode and real-time control mode, so as to evaluate effects of the operation mode on the system performance and to develop a feasible control strategy. Results obtained from fixed-time control study indicate that the variations of the pH and oxidation-reduction potential（ORP） profiles can represent dynamic characteristics of system and the cycle sequences can be controlled and optimized by the control points on the pH and ORP profiles. A control strategy was, therefore, developed and applied to real-time control mode. Compared with traditional mode, the total nitrogen（TN） removal can be increased by approximately 16% in modified mode and a mean TN removal of 92% was achieved in real-time control mode. Moreover, approximately 12.5% aeration energy was saved in real- time control mode. The result of this study shows that the performance of nitrogen removal was enhanced in modified operation mode. Moreover, the real-time control made it possible to optimize process operation and save aeration energy.展开更多
Traditional magneto-electric vibration sensors and servo accelerometers have severe shortcomings when used to measure vibration where low frequency components predominate.A low frequency characteristic extension for v...Traditional magneto-electric vibration sensors and servo accelerometers have severe shortcomings when used to measure vibration where low frequency components predominate.A low frequency characteristic extension for velocity vibration sensors is presented in this paper.The passive circuit technology,active compensation technology and the closed- cycle pole compensation technology are used to extend the measurable range and to improve low frequency characteristics of sensors.Thses three types of low frequency velocity vibration sensors have been developed and widely adopted in China.展开更多
Activity fragmentation provides a new approach for understanding the transformation of urban space and function in the information era. Numerous theoretical and empirical studies have been conducted on activity fragme...Activity fragmentation provides a new approach for understanding the transformation of urban space and function in the information era. Numerous theoretical and empirical studies have been conducted on activity fragmentation, but few studies have focused on the fragmentation of leisure activities. This study was intended to extend the extant literature by: 1) analysing the spatio-temporal fragmentation of physical and virtual leisure activities by using a dataset collected in Nanjing, China, and 2) evaluating the reasons of leisure activity fragmentation, as well as the potential spatial effect of activity fragmentation. The results indicated that virtual leisure activities are more fragmented than physical leisure activities, but the fragmentation of physical and virtual leisure activities varies on weekday and weekend, as well as in various locations and urban districts. In addition, the results suggested that sociodemographic factors and information and communication technology(ICT) variables distinctly affect the fragmentation of leisure activities. Meanwhile, the fragmentation of virtual leisure activities may enhance the transformation of traditional urban space by reallocating leisure activity times and locations.展开更多
The oblique detonation chamber has an extreme high and uneven thermal load due to the fast exothermic combustion process induced by oblique shock wave.The active cooling technology of over-pressure water is an effecti...The oblique detonation chamber has an extreme high and uneven thermal load due to the fast exothermic combustion process induced by oblique shock wave.The active cooling technology of over-pressure water is an effective thermal protection method with the development of additive manufacturing technology.The realizable κ-ε model coupling with Volume Fraction(VOF) model is applied to solve the boiling flow of cooling water in the mini-channels.The phase transition and heat transfer characteristics are systematically investigated under different pressures.The phase transition process is first observed in the position of oblique detonation wave,and the bubbly flow,the slug flow,the annular flow and the churn flow are captured in the characteristic cooling channel when boiling flow reaching steady stage.In the rear section of the channel,the uneven heat flux distribution of combustion chamber brings to the churn flow,which enhances the heat transfer compared to the annular flow.Compared to the atmospheric water,the appearances of churn flow and annular flow are significantly decreased with the increasing pressure,and they would disappear when the pressure is exceeding 0.5 MPa.The bubbly flow and slug flow play a dominant role when the pressure is higher than 1 MPa,showing that the over-pressure water can significantly enhance the cooling efficiency of the oblique detonation chamber.With the rise of water pressure,the time point of the appearance of phase transition is obviously lagged because of the increasing latent heat of vaporization,and the cooling efficiency is significantly increased due to the simpler phase transition in higher pressure,which means the over-pressure water could withstand longer heat load of oblique detonation engine.展开更多
Utilizing the cross sections for 93Nb（n, 2n）93mNb or 27Al（n, a）24Na reactions as monitors, the cross sections for the reactions 115Sn（n, p）115mIn, 116Sn（n, p）116mIn, 117Sn（n, p）117In and 117Sn（n, p）117mIn ...Utilizing the cross sections for 93Nb（n, 2n）93mNb or 27Al（n, a）24Na reactions as monitors, the cross sections for the reactions 115Sn（n, p）115mIn, 116Sn（n, p）116mIn, 117Sn（n, p）117In and 117Sn（n, p）117mIn have been measured at neutron energy ranging from 13.5 to 14.6 MeV through activation technology. Then, the results of present work were compared with the published experimental data.展开更多
文摘Phosphorus is one of the most important nutrients required to support various kinds of biodegradation processes. As this particular nutrient is not included in the activated sludge model no. 1 （ASM1）, this study extended this model in order to determine the fate of phosphorus during the biodegradation processes. When some of the kinetics parameters are modified using observed data from the restoration project of the Xuxi River in Wuxi City, China, from August 25 to 31 in 2009, the extended model shows excellent results. In order to obtain optimum values of coefficients of nitrogen and phosphorus, the mass fraction method was used to ensure that the final results were reasonable and practically relevant. The temporal distribution of the data calculated with the extended ASM1 approximates that of the observed data.
文摘Rice is the staple food of more than half of the world’s Population.The production,processing and management of paddy rice have provided the basic conditions for the living of mankind.The production of rice has not only created
文摘Relaxed Stable Stability （RSS） in an important part of the active control technology. It is a new way to raise the flying speed, distance and maneuverability of missile. Depth study of RSS technology plays an important role for the new concept missile design. This paper describes the detailed definition of RSS and its advantages, pres- ents the research status and prospects for its application in the design of new missiles.
基金financially supported by the National Key R&D Program of China (Nos. 2019YFC1907101 and 2021YFC1910504)Key R&D Program of Ningxia Hui Autonomous Region (Nos. 2020BCE01001 and 2021BEG 01003)+3 种基金National Natural Science Foundation of China (Nos. U2002212 and 51672024)Xijiang Innovation and Entrepreneurship Team (No. 2017A0109004)the Fundamental Research Funds for the Central Universities (Nos. FRF-BD20-24A, FRF-TP-20-031A1, FRF-IC-19-017Z, FRF-GF-19032B, and 06500141)Integration of Green Key Process Systems MIIT
文摘Industrial solid waste(ISW)-cement blends have the advantages of low carbon,low energy consumption,and low pollution,but their clinker replacement level in low carbon cement is generally low.To address this challenge,this study considers the latest progress and development trends in the ISW-cement blend research,focusing on the activation of ISWs,the formation of ISW-cement blends,and their associated hydration mechanisms.After the mechanical activation of ISWs,the D50(average size)typically drops below 10μm,and the specific surface area increases above 350 m2/kg.Thermal activation can increase the glassy-phase content and reactivity of ISWs,where the coal gangue activation temperature is usually set at 400-1000°C.Furthermore,the roles of ISWs in the hydration of ISW-cement blends are divided into physical and chemical roles.The physical action of ISWs usually acts in the early stage of the hydration of ISW-cement blends.Subsequently,ISWs participate in the hydration reaction of ISW-cement blends to generate products,such as C-(A)-S-H gels.Moreover,alkali activation affects the hydration kinetics of ISW-cement blends and modifies the proportion of gels.Environmental impacts and costs of ISW-cement blends have also been discussed to guide stakeholders in selecting sustainable ISWs.
基金supported by the Environment and Water Industry Development Scheme of Singapore-The Process Control and Enhanced Biological Nutrient Removal of CSBR Process (No. EDB S07/1-53974082)the National Key Technologies R&D Program of China during the Eleventh Five-year Plan Period (No. 2006BAC19B03)+1 种基金the Project of Scientific Research Base and Scientific Innovation Platform of Beijing Municipal Education Commission (No. PXM2008-014204-050843)the Funding Project by Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality (No. PHR20090502)
文摘A bench-scale cyclic activated sludge technology （CAST） was operated to study the biological phosphorus removal performance and a series of batch tests was carried out to demonstrate the accumulation of denitrifying polyphosphate-accumulating organisms （DNPAOs） in CAST system. Under all operating conditions, step-feed CAST with enough carbon sources in influent had the highest nitrogen and phosphorus removal efficiency as well as good sludge settling performance. The average removal rate of COD, NH4^＋-N, PO4^3--P and total nitrogen （TN） was 88.2%, 98.7%, 97.5% and 92.1%, respectively. The average sludge volume index （SVI） was 133 mL/g. The optimum anaerobic/aerobic/anoxic （AOA） conditions for the cultivation of DNPAOs could be achieved by alternating anoxic/oxic operational strategy, thus a significant denitrifying phosphorus removal occurred in step-feed CAST. The denitrification of NO^x--N completed quickly due to step-feed operation and enough carbon sources, which could enhance phosphorus release and further phosphorus uptake capability of the system. Batch tests also proved that polyphosphate-accumulating organisms （PAOs） in the step-feed process had strong denitrifying phosphorus removal capacity. Both nitrate and nitrite could be used as electron acceptors in denitrifying phosphorus removal. Low COD supply with step-feed operation strategy would favor DNPAOs accumulation.
基金The Project of Beijing Science and Technology Committee (No.020620010120) ,the Hi_Tech Research and Development Program(863) of China (No.2004AA601020) ,the Project under Key International Cooperative Programs of NSFC(No.50521140075) and the Project of Key Laboratory of Beiing
文摘A bench-scale reactor（72 L） red with domestic sewage, was operated more than 3 months with three operation modes： traditional mode, modified mode and real-time control mode, so as to evaluate effects of the operation mode on the system performance and to develop a feasible control strategy. Results obtained from fixed-time control study indicate that the variations of the pH and oxidation-reduction potential（ORP） profiles can represent dynamic characteristics of system and the cycle sequences can be controlled and optimized by the control points on the pH and ORP profiles. A control strategy was, therefore, developed and applied to real-time control mode. Compared with traditional mode, the total nitrogen（TN） removal can be increased by approximately 16% in modified mode and a mean TN removal of 92% was achieved in real-time control mode. Moreover, approximately 12.5% aeration energy was saved in real- time control mode. The result of this study shows that the performance of nitrogen removal was enhanced in modified operation mode. Moreover, the real-time control made it possible to optimize process operation and save aeration energy.
基金The Ministry of Science and Technology Special Foundation Grant No.217Harbin Important Science Technology Foundation Grant No.0014211044
文摘Traditional magneto-electric vibration sensors and servo accelerometers have severe shortcomings when used to measure vibration where low frequency components predominate.A low frequency characteristic extension for velocity vibration sensors is presented in this paper.The passive circuit technology,active compensation technology and the closed- cycle pole compensation technology are used to extend the measurable range and to improve low frequency characteristics of sensors.Thses three types of low frequency velocity vibration sensors have been developed and widely adopted in China.
基金Under the auspices of National Natural Science Foundation of China(No.41571146,41301166)
文摘Activity fragmentation provides a new approach for understanding the transformation of urban space and function in the information era. Numerous theoretical and empirical studies have been conducted on activity fragmentation, but few studies have focused on the fragmentation of leisure activities. This study was intended to extend the extant literature by: 1) analysing the spatio-temporal fragmentation of physical and virtual leisure activities by using a dataset collected in Nanjing, China, and 2) evaluating the reasons of leisure activity fragmentation, as well as the potential spatial effect of activity fragmentation. The results indicated that virtual leisure activities are more fragmented than physical leisure activities, but the fragmentation of physical and virtual leisure activities varies on weekday and weekend, as well as in various locations and urban districts. In addition, the results suggested that sociodemographic factors and information and communication technology(ICT) variables distinctly affect the fragmentation of leisure activities. Meanwhile, the fragmentation of virtual leisure activities may enhance the transformation of traditional urban space by reallocating leisure activity times and locations.
基金supports provided by Science Center for Gas Turbine Project (P2022-B-Ⅱ-028-001).
文摘The oblique detonation chamber has an extreme high and uneven thermal load due to the fast exothermic combustion process induced by oblique shock wave.The active cooling technology of over-pressure water is an effective thermal protection method with the development of additive manufacturing technology.The realizable κ-ε model coupling with Volume Fraction(VOF) model is applied to solve the boiling flow of cooling water in the mini-channels.The phase transition and heat transfer characteristics are systematically investigated under different pressures.The phase transition process is first observed in the position of oblique detonation wave,and the bubbly flow,the slug flow,the annular flow and the churn flow are captured in the characteristic cooling channel when boiling flow reaching steady stage.In the rear section of the channel,the uneven heat flux distribution of combustion chamber brings to the churn flow,which enhances the heat transfer compared to the annular flow.Compared to the atmospheric water,the appearances of churn flow and annular flow are significantly decreased with the increasing pressure,and they would disappear when the pressure is exceeding 0.5 MPa.The bubbly flow and slug flow play a dominant role when the pressure is higher than 1 MPa,showing that the over-pressure water can significantly enhance the cooling efficiency of the oblique detonation chamber.With the rise of water pressure,the time point of the appearance of phase transition is obviously lagged because of the increasing latent heat of vaporization,and the cooling efficiency is significantly increased due to the simpler phase transition in higher pressure,which means the over-pressure water could withstand longer heat load of oblique detonation engine.
基金Supported by Nature Science Foundation of Lan zhou University of Technology (Q200805)
文摘Utilizing the cross sections for 93Nb（n, 2n）93mNb or 27Al（n, a）24Na reactions as monitors, the cross sections for the reactions 115Sn（n, p）115mIn, 116Sn（n, p）116mIn, 117Sn（n, p）117In and 117Sn（n, p）117mIn have been measured at neutron energy ranging from 13.5 to 14.6 MeV through activation technology. Then, the results of present work were compared with the published experimental data.
