The determination of gas pressure before uncovering coal in cross-cuts and in shafts is one of the important steps in pre- dicting coal and gas outbursts. However, the time spent for testing gas pressure is, at presen...The determination of gas pressure before uncovering coal in cross-cuts and in shafts is one of the important steps in pre- dicting coal and gas outbursts. However, the time spent for testing gas pressure is, at present, very long, seriously affecting the ap- plication of outburst prediction techniques in opening coal seams in cross-cuts and shafts. In order to reduce the time needed in gas pressure tests and to improve the accuracy of tests, we analyzed the process of gas pressure tests and examined the effect of the length of boreholes in coal seams in tests. The result shows that 1) the shorter the borehole, the easier the real pressure value of gas can be obtained and 2) the main factors affecting the time spent in gas pressure tests are the length of the borehole in coal seams, the gas emission time after the borehole has been formed and the quality of the borehole-sealing. The longer the length of the bore- hole, the longer the gas emission time and the larger the pressure-relief circle formed around the borehole, the longer the time needed for pressure tests. By controlling the length of the borehole in a test case in the Huainan mining area, and adopting a quick sealing technique using a sticky liquid method, the sealing quality was clearly improved and the gas emission time as well as the amount of gas discharged greatly decreased. Before the method described, the time required for the gas pressure to increase during the pressure test process, was more than 10 days. With our new method the required time is only 5 hours. In addition, the accuracy of the gas pressure test is greatly improved.展开更多
Objective： Spontaneous intracranial hypotension （SIH） is recognized far more commonly than ever before. Though usually characterized by low cerebrospinal fluid （CSF） pressure, some patients with SIH are observed ...Objective： Spontaneous intracranial hypotension （SIH） is recognized far more commonly than ever before. Though usually characterized by low cerebrospinal fluid （CSF） pressure, some patients with SIH are observed to have normal pressure values. In this study, we aimed to confirm the proportion of patients with normal CSF opening pressure （CSF OP） and explore the factors affecting CSF OP in SIH patients. Methods： We retrospectively reviewed 206 consecutive SIH patients and analyzed their clinical and imaging variables （including demographic data, body mass index （BMI）, duration of symptoms, and brain imaging findings）. Univariate and multiVariate analyses were performed to identify the potential factors affecting CSF OP. Results： In a total of 114 （55.3%） cases the CSF OP was 〈60 mmH2O （1 mmH2O=9.80665 Pa）, in 90 （43.7%） cases it was between 60 and 200 mmH2O, and in 2 （1.0%） cases it was 〉200 mmH2O. Univadate analysis showed that the duration of symptoms （P〈0.001）, BMI （P〈0.001）, and age （P=0.024） were positively correlated with CSF OP. However, multivariate analysis suggested that only the duration of symptoms （P〈0.001） and BMI （P〈0.001） were strongly correlated with CSF OP. A relatively high R2 of 0.681 was obtained for the multivariate model. Conclusions： Our study indicated that in patients without a low CSF OP, a diagnosis of SIH should not be excluded. BMI and the duration of symptoms can influence CSF OP in SIH patients, and other potential factors need further investigation.展开更多
基金supported by the National Basic Research Program of China (No.2006CB202204-3).
文摘The determination of gas pressure before uncovering coal in cross-cuts and in shafts is one of the important steps in pre- dicting coal and gas outbursts. However, the time spent for testing gas pressure is, at present, very long, seriously affecting the ap- plication of outburst prediction techniques in opening coal seams in cross-cuts and shafts. In order to reduce the time needed in gas pressure tests and to improve the accuracy of tests, we analyzed the process of gas pressure tests and examined the effect of the length of boreholes in coal seams in tests. The result shows that 1) the shorter the borehole, the easier the real pressure value of gas can be obtained and 2) the main factors affecting the time spent in gas pressure tests are the length of the borehole in coal seams, the gas emission time after the borehole has been formed and the quality of the borehole-sealing. The longer the length of the bore- hole, the longer the gas emission time and the larger the pressure-relief circle formed around the borehole, the longer the time needed for pressure tests. By controlling the length of the borehole in a test case in the Huainan mining area, and adopting a quick sealing technique using a sticky liquid method, the sealing quality was clearly improved and the gas emission time as well as the amount of gas discharged greatly decreased. Before the method described, the time required for the gas pressure to increase during the pressure test process, was more than 10 days. With our new method the required time is only 5 hours. In addition, the accuracy of the gas pressure test is greatly improved.
文摘Objective： Spontaneous intracranial hypotension （SIH） is recognized far more commonly than ever before. Though usually characterized by low cerebrospinal fluid （CSF） pressure, some patients with SIH are observed to have normal pressure values. In this study, we aimed to confirm the proportion of patients with normal CSF opening pressure （CSF OP） and explore the factors affecting CSF OP in SIH patients. Methods： We retrospectively reviewed 206 consecutive SIH patients and analyzed their clinical and imaging variables （including demographic data, body mass index （BMI）, duration of symptoms, and brain imaging findings）. Univariate and multiVariate analyses were performed to identify the potential factors affecting CSF OP. Results： In a total of 114 （55.3%） cases the CSF OP was 〈60 mmH2O （1 mmH2O=9.80665 Pa）, in 90 （43.7%） cases it was between 60 and 200 mmH2O, and in 2 （1.0%） cases it was 〉200 mmH2O. Univadate analysis showed that the duration of symptoms （P〈0.001）, BMI （P〈0.001）, and age （P=0.024） were positively correlated with CSF OP. However, multivariate analysis suggested that only the duration of symptoms （P〈0.001） and BMI （P〈0.001） were strongly correlated with CSF OP. A relatively high R2 of 0.681 was obtained for the multivariate model. Conclusions： Our study indicated that in patients without a low CSF OP, a diagnosis of SIH should not be excluded. BMI and the duration of symptoms can influence CSF OP in SIH patients, and other potential factors need further investigation.
