With the rapid development of transportation industry in China, fire accidents frequently happen in railway tunnels. Fire accidents that happened in railway tunnels can be roughly divided into three types: fire accide...With the rapid development of transportation industry in China, fire accidents frequently happen in railway tunnels. Fire accidents that happened in railway tunnels can be roughly divided into three types: fire accidents of passenger trains; those of freight trains; and those of oil tank trains. The most inflammable and dangerous among them is the fire accidents of oil tank trains, since oil has extremely great danger--it keeps burning long and extensively after it catches fire and the temperature rises fast with a highest temperature of the central flame over 1 000℃ and in some part the temperature goes as high as 1 200℃-1 600℃, which makes it rather difficult to extinguish fire, and thus leads to great damage to tunnel lining. From 1976 to 1998, there have been 8 serious tank train fires accident happened in railway tunnel in China, train traffic had been held up for 2 500 hours and more than 300 person injured (115 person died). As a result, the direct economic loss exceeded RMB30 million and the indirect economic loss was inestimable. Aimed at existing problems in research of fire accident in railway tunnel at present in China, in this paper, following contents have been focused on: 1 The Test and Study of Damage Degree of Tunnel Lining under Different Burning Temperature Grades Adopting the experimental means of really burning down for concrete material and members of tunnel lining under different fire temperature and different ablating time, the rule of change of mechanics behavior and damage degree of lining structure after withstanding high temperature is analyzed, and the empirical curves are obtained. The contents include: (1)The test method, measuring process, and instrument and equipment used. (2)The variety regulation of damage degree (thickness of burn, loosen, shelling) of lining concrete under different fire temperature and different ablating time. (3)The rule of change of compress strength of lining concrete under different fire temperature and different ablating time, as well as the differ展开更多
Background:There are an increasing number of patients with oral sensory complaints(OSCs)presenting to our dental clinic.For most dentists,it is difficult to distinguish burning mouth syndrome(BMS)from other oral mucos...Background:There are an increasing number of patients with oral sensory complaints(OSCs)presenting to our dental clinic.For most dentists,it is difficult to distinguish burning mouth syndrome(BMS)from other oral mucosal diseases that may cause symptoms such as burning mouth.It is beneficial to effectively distinguish OSC patients to reduce misdiagnosis and eliminate burning symptoms as much as possible.Methods:Patients with oral burning sensations in the oral mucosal disease clinic were collected from the Peking University Hospital of Stomatology between September 1,2014 and December 31,2018.After excluding oral candidiasis,anemic stomatitis,dental material allergy,and other diseases from patients with oral sensory complaints,basic conditions such as gender,age,education level,job status,hyperglycemia,hypertension,hyperlipidemia,history of brain abnormalities,history of cervical spondylitis,history of thyroid disease,history of thyroid disease and insomnia were obtained.The BMS patients were compared with the control group.The t test and Chi-square test were used for statistical analysis to compare the clinical symptoms of these diseases and explore the risk factors for BMS.Results:In this case-control study,395 patients(321 females and 74 males,mean age 55.26±10.51 years)with oral sensory complaints and 391 healthy controls(281 females and 110 males,mean age 47.11±13.10 years)were enrolled,among which,8.4%(33/395)had oral candidiasis,1.3%(5/395)had dental material allergy,0.8%(3/395)had anemic stomatitis and 0.5%(2/395)had lichen planus.A total of 352 patients were eventually diagnosed with BMS.Anxiety and depression were more severe in BMS patients,as were the incidences of sleep disorders and brain abnormalities.Logistic regression analysis showed that age(odds ratio[OR]=2.79,95%confidence interval[CI]:1.61-4.83,P<0.001),total cholesterol level(OR=2.92,95%CI:1.32-6.50,P=0.009)and anxiety score(OR=1.75,95%CI:1.01-2.77,P=0.017)significantly increased the incidence of BMS.Patients with hyperglycemia(OR=0.46,95%展开更多
文摘With the rapid development of transportation industry in China, fire accidents frequently happen in railway tunnels. Fire accidents that happened in railway tunnels can be roughly divided into three types: fire accidents of passenger trains; those of freight trains; and those of oil tank trains. The most inflammable and dangerous among them is the fire accidents of oil tank trains, since oil has extremely great danger--it keeps burning long and extensively after it catches fire and the temperature rises fast with a highest temperature of the central flame over 1 000℃ and in some part the temperature goes as high as 1 200℃-1 600℃, which makes it rather difficult to extinguish fire, and thus leads to great damage to tunnel lining. From 1976 to 1998, there have been 8 serious tank train fires accident happened in railway tunnel in China, train traffic had been held up for 2 500 hours and more than 300 person injured (115 person died). As a result, the direct economic loss exceeded RMB30 million and the indirect economic loss was inestimable. Aimed at existing problems in research of fire accident in railway tunnel at present in China, in this paper, following contents have been focused on: 1 The Test and Study of Damage Degree of Tunnel Lining under Different Burning Temperature Grades Adopting the experimental means of really burning down for concrete material and members of tunnel lining under different fire temperature and different ablating time, the rule of change of mechanics behavior and damage degree of lining structure after withstanding high temperature is analyzed, and the empirical curves are obtained. The contents include: (1)The test method, measuring process, and instrument and equipment used. (2)The variety regulation of damage degree (thickness of burn, loosen, shelling) of lining concrete under different fire temperature and different ablating time. (3)The rule of change of compress strength of lining concrete under different fire temperature and different ablating time, as well as the differ
文摘Background:There are an increasing number of patients with oral sensory complaints(OSCs)presenting to our dental clinic.For most dentists,it is difficult to distinguish burning mouth syndrome(BMS)from other oral mucosal diseases that may cause symptoms such as burning mouth.It is beneficial to effectively distinguish OSC patients to reduce misdiagnosis and eliminate burning symptoms as much as possible.Methods:Patients with oral burning sensations in the oral mucosal disease clinic were collected from the Peking University Hospital of Stomatology between September 1,2014 and December 31,2018.After excluding oral candidiasis,anemic stomatitis,dental material allergy,and other diseases from patients with oral sensory complaints,basic conditions such as gender,age,education level,job status,hyperglycemia,hypertension,hyperlipidemia,history of brain abnormalities,history of cervical spondylitis,history of thyroid disease,history of thyroid disease and insomnia were obtained.The BMS patients were compared with the control group.The t test and Chi-square test were used for statistical analysis to compare the clinical symptoms of these diseases and explore the risk factors for BMS.Results:In this case-control study,395 patients(321 females and 74 males,mean age 55.26±10.51 years)with oral sensory complaints and 391 healthy controls(281 females and 110 males,mean age 47.11±13.10 years)were enrolled,among which,8.4%(33/395)had oral candidiasis,1.3%(5/395)had dental material allergy,0.8%(3/395)had anemic stomatitis and 0.5%(2/395)had lichen planus.A total of 352 patients were eventually diagnosed with BMS.Anxiety and depression were more severe in BMS patients,as were the incidences of sleep disorders and brain abnormalities.Logistic regression analysis showed that age(odds ratio[OR]=2.79,95%confidence interval[CI]:1.61-4.83,P<0.001),total cholesterol level(OR=2.92,95%CI:1.32-6.50,P=0.009)and anxiety score(OR=1.75,95%CI:1.01-2.77,P=0.017)significantly increased the incidence of BMS.Patients with hyperglycemia(OR=0.46,95%
