A three-step damage identification method based on dynamic characteristics is proposed to improve the structure reliability and security and avoid serious accident. In the proposed method, the frequency and difference...A three-step damage identification method based on dynamic characteristics is proposed to improve the structure reliability and security and avoid serious accident. In the proposed method, the frequency and difference of modal curvature(DMC) are used as damage indexes. Firstly, the detection of the occurrence of damage is addressed by the frequency or the square of frequency change. Then the damage location inside the structure is measured by the DMC. Finally, with the stiffness reduction rate as a damage factor, the amount of damage is estimated by the optimization algorithm. The three-step damage identification method has been validated by conducting the simulation on a cantilever beam and the shaking table test on a submerged bridge. The results show that the method proposed in this paper can effectively solve the damage identification problem in theory and engineering practice.展开更多
In April 2009, a new strain of influenza subtype H 1N 1 emerged due to the rearrangement of two RNA segments. The strain incorporated two segments of the genome of porcine origin and was officially designated as A/Cal...In April 2009, a new strain of influenza subtype H 1N 1 emerged due to the rearrangement of two RNA segments. The strain incorporated two segments of the genome of porcine origin and was officially designated as A/CaliforniaJ4/2009/H1N1. In June 2009, alarmed by the infection＇s progress, the World Health Organization （WHO） declared the ＂level six＂ of the geographical progression scale for epidemics and kept it at that level until August of the following year. The Portuguese media activated the public health alarm and integrated it into its agenda, but the volume and severity indicators of the news coverage did not correspond to the epidemiological indicators of progression. This paper describes how two narratives with different rhythms for the swine flu pandemic de facto emerged.展开更多
Village civil cases in the Qing Dynasty mainly dealt with households and marriage,land,and debts,etc.It was not uncommon for village disputes to end up in court,which functioned as a vent to release the sense of griev...Village civil cases in the Qing Dynasty mainly dealt with households and marriage,land,and debts,etc.It was not uncommon for village disputes to end up in court,which functioned as a vent to release the sense of grievance felt by the disputants.Seemingly trivial cases were thus not trivial at all for those concerned.Prefectural or county officials’mishandling of a petty civil case could spark village conflicts.As a consequence,such trials were seen as a sensitive issue in rural governance.After the 1860s,the unequal treaties had allowed Western missionaries to proselytize deep into the North China countryside,offering“political protection”for their converts in an attempt to maximize their number.The missionaries interfered extensively in village judicial actions,taking the side of their converts in civil lawsuits that pitted church members against ordinary people.This led to a general situation of“deceitful converts against honest men,”making the latter feel they were the victims of injustice.The channels that would have allowed the ordinary villagers to vent their grievances via litigation were thus blocked up.Their accumulated resentment burst its barriers and finally exploded in the violence of the Boxer Uprising.展开更多
基金Supported by the National Basic Research Program of China("973"Program,No.2011CB013605-4)the National Natural Science Foundation of China(No.51178079)the Major Program of National Natural Science Foundation of China(No.90915011 and No.91315301)
文摘A three-step damage identification method based on dynamic characteristics is proposed to improve the structure reliability and security and avoid serious accident. In the proposed method, the frequency and difference of modal curvature(DMC) are used as damage indexes. Firstly, the detection of the occurrence of damage is addressed by the frequency or the square of frequency change. Then the damage location inside the structure is measured by the DMC. Finally, with the stiffness reduction rate as a damage factor, the amount of damage is estimated by the optimization algorithm. The three-step damage identification method has been validated by conducting the simulation on a cantilever beam and the shaking table test on a submerged bridge. The results show that the method proposed in this paper can effectively solve the damage identification problem in theory and engineering practice.
文摘In April 2009, a new strain of influenza subtype H 1N 1 emerged due to the rearrangement of two RNA segments. The strain incorporated two segments of the genome of porcine origin and was officially designated as A/CaliforniaJ4/2009/H1N1. In June 2009, alarmed by the infection＇s progress, the World Health Organization （WHO） declared the ＂level six＂ of the geographical progression scale for epidemics and kept it at that level until August of the following year. The Portuguese media activated the public health alarm and integrated it into its agenda, but the volume and severity indicators of the news coverage did not correspond to the epidemiological indicators of progression. This paper describes how two narratives with different rhythms for the swine flu pandemic de facto emerged.
文摘Village civil cases in the Qing Dynasty mainly dealt with households and marriage,land,and debts,etc.It was not uncommon for village disputes to end up in court,which functioned as a vent to release the sense of grievance felt by the disputants.Seemingly trivial cases were thus not trivial at all for those concerned.Prefectural or county officials’mishandling of a petty civil case could spark village conflicts.As a consequence,such trials were seen as a sensitive issue in rural governance.After the 1860s,the unequal treaties had allowed Western missionaries to proselytize deep into the North China countryside,offering“political protection”for their converts in an attempt to maximize their number.The missionaries interfered extensively in village judicial actions,taking the side of their converts in civil lawsuits that pitted church members against ordinary people.This led to a general situation of“deceitful converts against honest men,”making the latter feel they were the victims of injustice.The channels that would have allowed the ordinary villagers to vent their grievances via litigation were thus blocked up.Their accumulated resentment burst its barriers and finally exploded in the violence of the Boxer Uprising.
