On May 21,2021,a local case of coronavirus disease 2019(COVID-19)was confirmed in a 75-year-old woman(experienced onset of symptoms on May 18)in Liwan District,Guangzhou City,Guangdong Province,China.The number of inf...On May 21,2021,a local case of coronavirus disease 2019(COVID-19)was confirmed in a 75-year-old woman(experienced onset of symptoms on May 18)in Liwan District,Guangzhou City,Guangdong Province,China.The number of infections has increased in the following 10 days and led to 5 generations of transmission.展开更多
针对φ73.0 mm×5.51 mm N80 EU TBG油管粘扣和脱扣事故进行了深入调查研究,对粘扣和脱扣的油管样品进行了宏观分析;对该批油管螺纹接头加工质量进行了全面检测;对油管材质进行了理化试验;对油管上、卸扣性能和拉伸性能进行了系统...针对φ73.0 mm×5.51 mm N80 EU TBG油管粘扣和脱扣事故进行了深入调查研究,对粘扣和脱扣的油管样品进行了宏观分析;对该批油管螺纹接头加工质量进行了全面检测;对油管材质进行了理化试验;对油管上、卸扣性能和拉伸性能进行了系统试验。通过试验分析和研究,认为油管螺纹加工质量和材质符合标准,油管脱扣是由于粘扣后接头连接强度降低所致,油管粘扣是操作不当引起的。展开更多
Tangjiashan Barrier Lake is one of the largest barrier lakes caused by the Wenchuan Earthquake. Its risk analysis, emergency plan and effect of the emergency plan are introduced in this paper. The dam height of Tangji...Tangjiashan Barrier Lake is one of the largest barrier lakes caused by the Wenchuan Earthquake. Its risk analysis, emergency plan and effect of the emergency plan are introduced in this paper. The dam height of Tangjiashan Barrier Dam is about 105 m, and the reservoir storage capacity is 3.2×108 m3. When the dam broke the flood peak were estimated to be larger than 48000 m3/s, which might cause a enormous disaster to the downstream cities and residents. A discharge channel with 13 m deep and 8 m wide was drug, so that the water may flow out of the lake before the dam breaks. As a result, the drainage and risk mitigation project are successful. During the drainage process, the flood peak was about 6500 m3/s, and about 1.6×108 m3 of water was drained off and the residual reservoir capacity was only 8.97×107 m3. A new channel with average width 100 m was formed, which can bear floods of 200 years frequency. The successful experience and the collected data can be used to deal with the similar natural disasters in future.展开更多
With the rapid development of modern distribution network and the access of distributed generation,the network structure is becoming increasingly complex.Frequent single-phase break faults have seriously affected equi...With the rapid development of modern distribution network and the access of distributed generation,the network structure is becoming increasingly complex.Frequent single-phase break faults have seriously affected equipment and personal safety and stable operation of the power system.However,with the development and application of the composite neutral grounding modes,the protection of single-phase break fault is facing new challenges.This paper proposes a protection method of single-phase break fault for distribution network considering the influence of neutral grounding modes.The characteristics of neutral voltage and sequence current are analyzed under normal operation and single-phase break fault with different grounding modes.Following this,the protection criterion based on neutral voltage and sequence current variation is constructed.The protection method of singlephase break fault for distribution network is proposed,which is applicable for various neutral grounding modes.Theoretical analysis and simulation results show that the protection method is less affected by system asymmetry,fault location and load distribution.The method has higher sensitivity,reliability and adaptability.展开更多
模拟现场施工条件,测定了不同温度下灌注袋中的中国铁路轨道系统Ⅰ型水泥乳化沥青(cement and emulsified asphalt,CA)砂浆膨胀率随时间变化,并测定了浆体pH值随时间的变化。研究发现CA砂浆早期膨胀可分为4个阶段:混合后0～3h,砂浆收缩;...模拟现场施工条件,测定了不同温度下灌注袋中的中国铁路轨道系统Ⅰ型水泥乳化沥青(cement and emulsified asphalt,CA)砂浆膨胀率随时间变化,并测定了浆体pH值随时间的变化。研究发现CA砂浆早期膨胀可分为4个阶段:混合后0～3h,砂浆收缩;3～6h,砂浆迅速膨胀;6～10h,砂浆再收缩;10 h以后,砂浆体积较为稳定。温度越高,各阶段开始时间越早,持续时间也越短;20～35℃,浆体膨胀率随温度升高而增大,但温度为35～45℃时,砂浆膨胀率随温度升高反而减小,温度对浆体pH值随时间变化的影响也有类似规律。扫描电子显微镜和能谱仪结果表明:对于水化10d的水泥乳化沥青砂浆,20℃浆体中可看到大量与钙矾石有关的针状物,而55℃浆体中除沥青膜层外,水泥水化产物并不明显。高温下(>35℃)乳化沥青破乳,包裹铝粉与水泥颗粒,使铝粉发气反应受到抑制可能是导致膨胀率、pH值等变化异常的原因。展开更多
An unstructured finite-volume numerical algorithm was presented for solution of the two-dimensional shallow water equations, based on triangular or arbitrary quadrilateral meshes. The Roe type approximate Riemann solv...An unstructured finite-volume numerical algorithm was presented for solution of the two-dimensional shallow water equations, based on triangular or arbitrary quadrilateral meshes. The Roe type approximate Riemann solver was used to the system. A second-order TVD scheme with the van Leer limiter was used in the space discretization and a two-step Runge-Kutta approach was used in the time discretization. An upwind, as opposed to a pointwise, treatment of the slope source terms was adopted and the semi-implicit treatment was used for the friction source terms. Verification for two-dimension dam-break problems are carried out by comparing the present results with others and very good agreement is shown.展开更多
Objective: To explore the clinical efficacy of the principle of activating blood circulation to break stasis (ABCBS) and its influence on platelet membranous protein particle (GMP-140) and D 2 dimer (D-dimer) before...Objective: To explore the clinical efficacy of the principle of activating blood circulation to break stasis (ABCBS) and its influence on platelet membranous protein particle (GMP-140) and D 2 dimer (D-dimer) before and after treatment. Methods: Eighty-eight patients with blood stasis syndrome (BSS) of acute cerebral infarction (ACI) were randomly divided into two groups, both of which were treated with conventional treatment, i.e. with western medicine (WM), with Salvia injection added through intravenously dripping.One of the two groups was used as the control and the other group as the treated group who had ABCBS herbs orally taken in addition. The duration of treatment course for both groups was 3 weeks. Results: There were changes in both groups over clinical symptoms, nerve function deficit scoring and GMP-140, D-dimer, but the treated group showed significantly better than that of the control group, ( P <0.05). Conclusion: ABCBS principle could serve as an important auxiliary treating method for BSS of ACI, as it can effectively alter the blood of ACI patients which was viscous, condense, coagulant and aggregating.展开更多
Based on the studies of the Songliao Basin characterized by Cretaceous down-warping, of the Jurassic compressional flexural Junggar basin and of the Bohai Bay Basin characterized by Paleogene rifting, the multiple-gra...Based on the studies of the Songliao Basin characterized by Cretaceous down-warping, of the Jurassic compressional flexural Junggar basin and of the Bohai Bay Basin characterized by Paleogene rifting, the multiple-grades slope break has developed in lacustrine basins of different origins. Their genetic types can be divided into tectonic slope break, depositional slope break and erodent slope break. The dominant agent of the slope break is tectogenesis, and the scale of slope breaks relates with the size of tectogenesis. The results of the study show that control of mutual grades slope breaks on atectonic traps mainly represent: 1) Atectonic traps develop close to mutual grades slope breaks, with beads-shaped distribution along the slope breaks. 2) In the longitudinal direction, the development of atectonic traps is characterized by the inheritance. 3) Different slope breaks and their different geographical positions can lead to different development types of atectonic traps. 4) A slope break can form different kinds of atectonic traps because of its great lateral variation. 5) The existence of mutual-grade slope breaks leads to different responses of erosion and deposition at different geographical positions in the basin. The oil source bed, reservoir and cap rock combination of atectonic traps is fine. 6) The oil-bearing condition of atectonic traps controlled by slope breaks is very favorable.展开更多
In active rift basins, tectonism is extremely important for sequence stratigraphic patterns, affecting both the sequence architecture and internal makeup. Sequence stratigraphic framework of a Paleogene rift successio...In active rift basins, tectonism is extremely important for sequence stratigraphic patterns, affecting both the sequence architecture and internal makeup. Sequence stratigraphic framework of a Paleogene rift succession in Qiongdongnan Basin, northern South China Sea, was built using seismic profiles, complemented by well logs and cores. One first-order and three second-order sequences were identified on the basis of basin-scale unconformities, and seven third-order sequences are defined by unconformities along the basin margins and correlative conformities within the central basin. Through unconformity analysis and backstripping procedure, the Paleogene synrift tectonic evolution of deep- water area of Qiongdongnan Basin was proved to be episodic, which can be divided into rifting stage-I, rifting stage-II and rifting stage-III. Episodic rifting resulted in the formation of various types of struc- tural slope break belts, which controlled different architectures and internal makeup of sequences. This study enhances the understanding of the control of tectonic evolution on sequence stratigraphic pat- terns and establishes relevant patterns in a typical rift basin, and further proposes the favorable sand- stone reservoirs developing in different sequence stratigraphic patterns, which will be pretty helpful for subtle pool exploration in deepwater area of petroliferous basins.展开更多
基金The Key-Area Research and Development Program of Guangdong Province(2019B111103001,2020B111107001)The National Natural Science Foundation of China(No.82041030).
文摘On May 21,2021,a local case of coronavirus disease 2019(COVID-19)was confirmed in a 75-year-old woman(experienced onset of symptoms on May 18)in Liwan District,Guangzhou City,Guangdong Province,China.The number of infections has increased in the following 10 days and led to 5 generations of transmission.
文摘针对φ73.0 mm×5.51 mm N80 EU TBG油管粘扣和脱扣事故进行了深入调查研究,对粘扣和脱扣的油管样品进行了宏观分析;对该批油管螺纹接头加工质量进行了全面检测;对油管材质进行了理化试验;对油管上、卸扣性能和拉伸性能进行了系统试验。通过试验分析和研究,认为油管螺纹加工质量和材质符合标准,油管脱扣是由于粘扣后接头连接强度降低所致,油管粘扣是操作不当引起的。
基金Supported by the National Basic Research Program of China ("973" Project) (Grant No. 2007CB714102)
文摘Tangjiashan Barrier Lake is one of the largest barrier lakes caused by the Wenchuan Earthquake. Its risk analysis, emergency plan and effect of the emergency plan are introduced in this paper. The dam height of Tangjiashan Barrier Dam is about 105 m, and the reservoir storage capacity is 3.2×108 m3. When the dam broke the flood peak were estimated to be larger than 48000 m3/s, which might cause a enormous disaster to the downstream cities and residents. A discharge channel with 13 m deep and 8 m wide was drug, so that the water may flow out of the lake before the dam breaks. As a result, the drainage and risk mitigation project are successful. During the drainage process, the flood peak was about 6500 m3/s, and about 1.6×108 m3 of water was drained off and the residual reservoir capacity was only 8.97×107 m3. A new channel with average width 100 m was formed, which can bear floods of 200 years frequency. The successful experience and the collected data can be used to deal with the similar natural disasters in future.
基金supported by the National Natural Science Foundation of China(NO.51877018).
文摘With the rapid development of modern distribution network and the access of distributed generation,the network structure is becoming increasingly complex.Frequent single-phase break faults have seriously affected equipment and personal safety and stable operation of the power system.However,with the development and application of the composite neutral grounding modes,the protection of single-phase break fault is facing new challenges.This paper proposes a protection method of single-phase break fault for distribution network considering the influence of neutral grounding modes.The characteristics of neutral voltage and sequence current are analyzed under normal operation and single-phase break fault with different grounding modes.Following this,the protection criterion based on neutral voltage and sequence current variation is constructed.The protection method of singlephase break fault for distribution network is proposed,which is applicable for various neutral grounding modes.Theoretical analysis and simulation results show that the protection method is less affected by system asymmetry,fault location and load distribution.The method has higher sensitivity,reliability and adaptability.
文摘模拟现场施工条件,测定了不同温度下灌注袋中的中国铁路轨道系统Ⅰ型水泥乳化沥青(cement and emulsified asphalt,CA)砂浆膨胀率随时间变化,并测定了浆体pH值随时间的变化。研究发现CA砂浆早期膨胀可分为4个阶段:混合后0～3h,砂浆收缩;3～6h,砂浆迅速膨胀;6～10h,砂浆再收缩;10 h以后,砂浆体积较为稳定。温度越高,各阶段开始时间越早,持续时间也越短;20～35℃,浆体膨胀率随温度升高而增大,但温度为35～45℃时,砂浆膨胀率随温度升高反而减小,温度对浆体pH值随时间变化的影响也有类似规律。扫描电子显微镜和能谱仪结果表明:对于水化10d的水泥乳化沥青砂浆,20℃浆体中可看到大量与钙矾石有关的针状物,而55℃浆体中除沥青膜层外,水泥水化产物并不明显。高温下(>35℃)乳化沥青破乳,包裹铝粉与水泥颗粒,使铝粉发气反应受到抑制可能是导致膨胀率、pH值等变化异常的原因。
文摘An unstructured finite-volume numerical algorithm was presented for solution of the two-dimensional shallow water equations, based on triangular or arbitrary quadrilateral meshes. The Roe type approximate Riemann solver was used to the system. A second-order TVD scheme with the van Leer limiter was used in the space discretization and a two-step Runge-Kutta approach was used in the time discretization. An upwind, as opposed to a pointwise, treatment of the slope source terms was adopted and the semi-implicit treatment was used for the friction source terms. Verification for two-dimension dam-break problems are carried out by comparing the present results with others and very good agreement is shown.
文摘Objective: To explore the clinical efficacy of the principle of activating blood circulation to break stasis (ABCBS) and its influence on platelet membranous protein particle (GMP-140) and D 2 dimer (D-dimer) before and after treatment. Methods: Eighty-eight patients with blood stasis syndrome (BSS) of acute cerebral infarction (ACI) were randomly divided into two groups, both of which were treated with conventional treatment, i.e. with western medicine (WM), with Salvia injection added through intravenously dripping.One of the two groups was used as the control and the other group as the treated group who had ABCBS herbs orally taken in addition. The duration of treatment course for both groups was 3 weeks. Results: There were changes in both groups over clinical symptoms, nerve function deficit scoring and GMP-140, D-dimer, but the treated group showed significantly better than that of the control group, ( P <0.05). Conclusion: ABCBS principle could serve as an important auxiliary treating method for BSS of ACI, as it can effectively alter the blood of ACI patients which was viscous, condense, coagulant and aggregating.
文摘Based on the studies of the Songliao Basin characterized by Cretaceous down-warping, of the Jurassic compressional flexural Junggar basin and of the Bohai Bay Basin characterized by Paleogene rifting, the multiple-grades slope break has developed in lacustrine basins of different origins. Their genetic types can be divided into tectonic slope break, depositional slope break and erodent slope break. The dominant agent of the slope break is tectogenesis, and the scale of slope breaks relates with the size of tectogenesis. The results of the study show that control of mutual grades slope breaks on atectonic traps mainly represent: 1) Atectonic traps develop close to mutual grades slope breaks, with beads-shaped distribution along the slope breaks. 2) In the longitudinal direction, the development of atectonic traps is characterized by the inheritance. 3) Different slope breaks and their different geographical positions can lead to different development types of atectonic traps. 4) A slope break can form different kinds of atectonic traps because of its great lateral variation. 5) The existence of mutual-grade slope breaks leads to different responses of erosion and deposition at different geographical positions in the basin. The oil source bed, reservoir and cap rock combination of atectonic traps is fine. 6) The oil-bearing condition of atectonic traps controlled by slope breaks is very favorable.
基金supported by the National Science Foundation of China (NSFC) (Nos. 41272122, 41202074 and 41172123)the Major National Science and Technology Programs in the "Twelfth Five-Year" Plan of China (No. 2011ZX05009-002-02)+1 种基金the Open Research Program Foundation of Teaching Laboratory of China University of Geosciencesthe Foundation of Key Laboratory of Tectonics and Petroleum Resources (China University of Geosciences) of Ministry of Education (No. TPR-2013-14)
文摘In active rift basins, tectonism is extremely important for sequence stratigraphic patterns, affecting both the sequence architecture and internal makeup. Sequence stratigraphic framework of a Paleogene rift succession in Qiongdongnan Basin, northern South China Sea, was built using seismic profiles, complemented by well logs and cores. One first-order and three second-order sequences were identified on the basis of basin-scale unconformities, and seven third-order sequences are defined by unconformities along the basin margins and correlative conformities within the central basin. Through unconformity analysis and backstripping procedure, the Paleogene synrift tectonic evolution of deep- water area of Qiongdongnan Basin was proved to be episodic, which can be divided into rifting stage-I, rifting stage-II and rifting stage-III. Episodic rifting resulted in the formation of various types of struc- tural slope break belts, which controlled different architectures and internal makeup of sequences. This study enhances the understanding of the control of tectonic evolution on sequence stratigraphic pat- terns and establishes relevant patterns in a typical rift basin, and further proposes the favorable sand- stone reservoirs developing in different sequence stratigraphic patterns, which will be pretty helpful for subtle pool exploration in deepwater area of petroliferous basins.
