An in situ and ex situ reinforced powder metallurgy （PM） steel was prepared by the combination of high-energy ball milling and subsequent hot pressing of elemental mixed powders of Fe-10Cr-1Cu-1Ni-1Mo-2C by mass wit...An in situ and ex situ reinforced powder metallurgy （PM） steel was prepared by the combination of high-energy ball milling and subsequent hot pressing of elemental mixed powders of Fe-10Cr-1Cu-1Ni-1Mo-2C by mass with the addition of NbC particles. A 40-h milling pretreatment makes the powder particles nearly equiaxed with an average diameter of-8 μm, and the ferrite grain size is refined to -6 nm. The sintered density reaches 99.0%-99.7% of the theoretical value when the sintering is conducted at temperatures greater than 1000℃ for 30 min. In the sintered bulk specimens, the formation of an in situ M7C3 （M = Cr, Fe, Mo） phase is confirmed. MTC3 carbides with several hundred nanometers in size are uniformly distributed in the matrix. Some ultra-fine second phases of 50-200 nm form around the ex situ NbC and in situ M7C3 particles. The sintered steel exhibits an excellent combination of hardness （〉 Hv 500） and compressive strength （2100-2420 MPa）.展开更多
Vulnerability to natural disasters falls into three categories： exposure, resistance, and resilience, where resilience mainly refers to the capability of a pressure-bearing system to recover by returning to its initi...Vulnerability to natural disasters falls into three categories： exposure, resistance, and resilience, where resilience mainly refers to the capability of a pressure-bearing system to recover by returning to its initial state, that is, the ability to adapt to disaster pressure. Resilience is a major subject of research on disaster prevention and mitigation. This research mainly focuses on the ability of the hydraulic structure to recover from the significant impacts of typhoons. According to the load/unload response ratio theory, the degree of instability by which nonlinear systems can be identified according to the difference between load and unload responses was analyzed. This analysis was used as a basis to study the resilience of a hydraulic structure. Taking the Yangtze River embankments under the impact of Typhoon Matsa as an example, the ability of the typical sections of different types of embankments to adapt to the significant impact of the typhoon, i.e., the resilience of the hydraulic structure, is described with the help of the load/unload response ratio （L）. The results of the calculated resilience reflect the actual conditions of the structure and can be used to determine the applicability of the embankment section. The load/unload response ratio theory is one of the effective tools for calculating the resilience of hydraulic structures under the significant impacts of typhoons.展开更多
The treatment of malignant tumor is mainly based on modern medical treatment,after treatment,there are many adverse reactions,such as dizziness,headache,fever,numbness of limbs,pruritus,rash,spasm,phalacrosis,elevated...The treatment of malignant tumor is mainly based on modern medical treatment,after treatment,there are many adverse reactions,such as dizziness,headache,fever,numbness of limbs,pruritus,rash,spasm,phalacrosis,elevated blood pressure,anemia,myelosuppression,impaired functions of liver and kidney."Endogenous wind"is a part of Traditional Chinese medicine,and the researches are mainly focused on tumor metastasis and treatment.The researches on the adverse reactions associated with the treatment of malignant tumors are less.This paper is built on the theory of"endogenous wind"of Chinese medicine,and initially analyzes the progress of the research on adverse reactions of malignant tumors after treatment by modern medical means.展开更多
Internet-based virtual computing environment （iVCE） has been proposed to combine data centers and other kinds of computing resources on the Internet to provide efficient and economical services. Virtual machines （...Internet-based virtual computing environment （iVCE） has been proposed to combine data centers and other kinds of computing resources on the Internet to provide efficient and economical services. Virtual machines （VMs） have been widely used in iVCE to isolate different users/jobs and ensure trustworthiness, but traditionally VMs require a long period of time for booting, which cannot meet the requirement of iVCE＇s large-scale and highly dynamic applications. To address this problem, in this paper we design and implement VirtMan, a fast booting system for a large number of virtual machines in iVCE. VirtMan uses the Linux Small Computer System Interface （SCSI） target to remotely mount to the source image in a scalable hierarchy, and leverages the homogeneity of a set of VMs to transfer only necessary image data at runtime. We have implemented VirtMan both as a standalone system and for OpenStack. In our 100-server testbed, VirtMan boots up 1000 VMs （with a 15 CB image of Windows Server 2008） on 100 physical servers in less than 120 s, which is three orders of magnitude lower than current public clouds.展开更多
基金financially supported by the Key Technology R&D Program of the Ministry of Education of China(No.62501036011)the Fundamental Research Funds for the Central Universities of China(No.2012ZG0006)
文摘An in situ and ex situ reinforced powder metallurgy （PM） steel was prepared by the combination of high-energy ball milling and subsequent hot pressing of elemental mixed powders of Fe-10Cr-1Cu-1Ni-1Mo-2C by mass with the addition of NbC particles. A 40-h milling pretreatment makes the powder particles nearly equiaxed with an average diameter of-8 μm, and the ferrite grain size is refined to -6 nm. The sintered density reaches 99.0%-99.7% of the theoretical value when the sintering is conducted at temperatures greater than 1000℃ for 30 min. In the sintered bulk specimens, the formation of an in situ M7C3 （M = Cr, Fe, Mo） phase is confirmed. MTC3 carbides with several hundred nanometers in size are uniformly distributed in the matrix. Some ultra-fine second phases of 50-200 nm form around the ex situ NbC and in situ M7C3 particles. The sintered steel exhibits an excellent combination of hardness （〉 Hv 500） and compressive strength （2100-2420 MPa）.
基金supported by the National Natural Science Foundation of China (Grants No.50909066 and51179108)
文摘Vulnerability to natural disasters falls into three categories： exposure, resistance, and resilience, where resilience mainly refers to the capability of a pressure-bearing system to recover by returning to its initial state, that is, the ability to adapt to disaster pressure. Resilience is a major subject of research on disaster prevention and mitigation. This research mainly focuses on the ability of the hydraulic structure to recover from the significant impacts of typhoons. According to the load/unload response ratio theory, the degree of instability by which nonlinear systems can be identified according to the difference between load and unload responses was analyzed. This analysis was used as a basis to study the resilience of a hydraulic structure. Taking the Yangtze River embankments under the impact of Typhoon Matsa as an example, the ability of the typical sections of different types of embankments to adapt to the significant impact of the typhoon, i.e., the resilience of the hydraulic structure, is described with the help of the load/unload response ratio （L）. The results of the calculated resilience reflect the actual conditions of the structure and can be used to determine the applicability of the embankment section. The load/unload response ratio theory is one of the effective tools for calculating the resilience of hydraulic structures under the significant impacts of typhoons.
文摘The treatment of malignant tumor is mainly based on modern medical treatment,after treatment,there are many adverse reactions,such as dizziness,headache,fever,numbness of limbs,pruritus,rash,spasm,phalacrosis,elevated blood pressure,anemia,myelosuppression,impaired functions of liver and kidney."Endogenous wind"is a part of Traditional Chinese medicine,and the researches are mainly focused on tumor metastasis and treatment.The researches on the adverse reactions associated with the treatment of malignant tumors are less.This paper is built on the theory of"endogenous wind"of Chinese medicine,and initially analyzes the progress of the research on adverse reactions of malignant tumors after treatment by modern medical means.
基金supported by the National Natural Science Foundation of China(Nos.61379055 and 61379053)
文摘Internet-based virtual computing environment （iVCE） has been proposed to combine data centers and other kinds of computing resources on the Internet to provide efficient and economical services. Virtual machines （VMs） have been widely used in iVCE to isolate different users/jobs and ensure trustworthiness, but traditionally VMs require a long period of time for booting, which cannot meet the requirement of iVCE＇s large-scale and highly dynamic applications. To address this problem, in this paper we design and implement VirtMan, a fast booting system for a large number of virtual machines in iVCE. VirtMan uses the Linux Small Computer System Interface （SCSI） target to remotely mount to the source image in a scalable hierarchy, and leverages the homogeneity of a set of VMs to transfer only necessary image data at runtime. We have implemented VirtMan both as a standalone system and for OpenStack. In our 100-server testbed, VirtMan boots up 1000 VMs （with a 15 CB image of Windows Server 2008） on 100 physical servers in less than 120 s, which is three orders of magnitude lower than current public clouds.
