According to the principle of effective stress action of rock and soil, we established a mechanical model of water flooding into roadways,analyzed the constitutive relation of hydrodynamic pressure and contact pressur...According to the principle of effective stress action of rock and soil, we established a mechanical model of water flooding into roadways,analyzed the constitutive relation of hydrodynamic pressure and contact pressure of rock and soil and discovered that the process of pre-grouting of a roadway curtain is a dynamically balancing process in which effective stress keeps gradually in- creasing and pore water pressure gradually declines. In such a grouting process, the initial water plugging effect is realized when the effective stress and total stress reaches equilibrium. A rigid-flexible packing layer is designed behind the brickwork to increase the effective stress and reduce pore water pressure in order to have a permanent water proof performance. This provides a theoretical basis for roadway driving and permanent water prevention. The monitoring and application results show that the initial and perma- nent waterproof theory has provided an effective method for roadway driving and making it waterproof.展开更多
Water security in Africa has never been as starkly highlighted as the countdown to Day Zero in Cape Town. South Africa, where becauseof an unprecedented drought, the entire city of about 4 million residents could be w...Water security in Africa has never been as starkly highlighted as the countdown to Day Zero in Cape Town. South Africa, where becauseof an unprecedented drought, the entire city of about 4 million residents could be without water in July. Water restrictions for all residents are already in place and Day Zero has an activation date of July 9 (at the time of writing). If this catastrophe happens, it would make the famous tourist city that is frequently voted the world's most beautiful destination, earn another more dubious title that of the first major city in the world to ever run out of water.展开更多
Compared with traditional real-time forecasting,this paper proposes a Grey Markov Model(GMM) to forecast the maximum water levels at hydrological stations in the estuary area.The GMM combines the Grey System and Marko...Compared with traditional real-time forecasting,this paper proposes a Grey Markov Model(GMM) to forecast the maximum water levels at hydrological stations in the estuary area.The GMM combines the Grey System and Markov theory into a higher precision model.The GMM takes advantage of the Grey System to predict the trend values and uses the Markov theory to forecast fluctuation values,and thus gives forecast results involving two aspects of information.The procedure for forecasting annul maximum water levels with the GMM contains five main steps:1) establish the GM(1,1) model based on the data series;2) estimate the trend values;3) establish a Markov Model based on relative error series;4) modify the relative errors caused in step 2,and then obtain the relative errors of the second order estimation;5) compare the results with measured data and estimate the accuracy.The historical water level records(from 1960 to 1992) at Yuqiao Hydrological Station in the estuary area of the Haihe River near Tianjin,China are utilized to calibrate and verify the proposed model according to the above steps.Every 25 years' data are regarded as a hydro-sequence.Eight groups of simulated results show reasonable agreement between the predicted values and the measured data.The GMM is also applied to the 10 other hydrological stations in the same estuary.The forecast results for all of the hydrological stations are good or acceptable.The feasibility and effectiveness of this new forecasting model have been proved in this paper.展开更多
Hypertension, as the third cause of death, besides stroke and tuberculosis, amounts to 6.8 percent of the proportion of deaths at all ages in Indonesia. The prevalence of hypertension in Indonesia has reached 31.7 per...Hypertension, as the third cause of death, besides stroke and tuberculosis, amounts to 6.8 percent of the proportion of deaths at all ages in Indonesia. The prevalence of hypertension in Indonesia has reached 31.7 percent of the total adult population. Estimated, there are 76 percent of cases of hypertension in people who have not been diagnosed. Drinking enough ordinary water will help maximize the function of the body organs, in order to work optimally, so that the body metabolism will run well and normal. For smokers this amount shall be increased by half. The purpose of research was to know the effect of drinking water and other factors on the prevention of hypertension in working area Puskesmas Pasirkaliki Bandung. Design study was case control. The number of samples is 156 people, with a ratio of 1:1 (between cases and controls). Data were collected by interviewing. The bivariate analysis used chi square test, and multivariate analysis used logistic regression. The result of drinking enough ordinary water at least 6 cups a day contributes to prevent hypertension. For those who are still healthy, habit of drinking ordinary water is recommended at least 6 cups (1500 ml) per day. But for people who already have hypertension, heart and kidney diseases should be adjusted to the excretion organ.展开更多
Under the circumstance that deep mining is increasingly vulnerable to underlying limestone water, accurate detection of floor failure depth ranges at a mining face becomes rather critical to coal mine production in sa...Under the circumstance that deep mining is increasingly vulnerable to underlying limestone water, accurate detection of floor failure depth ranges at a mining face becomes rather critical to coal mine production in safety. Underground borehole fiber optic sensing technology is combined with 2-D parallel electrical surveying to comprehensively monitor and analyze development laws of floor deformation and failure. Moreover, a working face 1022 in a mine of Huaibei Mining Area was taken, for example, introducing the layout of monitoring borehole and installation of relevant sensing units. Based on the stope progress of a working face, data related to strain and geoelectric fields were collected regularly to analyze relationships of field source variation characteristics and strata deformation failures. In this way, the development mechanism of the floor deformation failure can be revealed. As demonstrated by results, the depth failure of the floor at coal seam 10 is calculated to be 15 m, while its disturbance depth turns out to be 22 m. Due to advanced stress, concentrated stope load and post-mining pressure relief, the floor experienced elastic deformation, shear deformation and swelling deformation successively. Without a doubt, testing results obtained have scientific guiding significance for mines with similar geological conditions.展开更多
基金Projects 50774078 supported by the National Natural Science Foundation of China 2007CB209400 by the National Basic Research Program of China
文摘According to the principle of effective stress action of rock and soil, we established a mechanical model of water flooding into roadways,analyzed the constitutive relation of hydrodynamic pressure and contact pressure of rock and soil and discovered that the process of pre-grouting of a roadway curtain is a dynamically balancing process in which effective stress keeps gradually in- creasing and pore water pressure gradually declines. In such a grouting process, the initial water plugging effect is realized when the effective stress and total stress reaches equilibrium. A rigid-flexible packing layer is designed behind the brickwork to increase the effective stress and reduce pore water pressure in order to have a permanent water proof performance. This provides a theoretical basis for roadway driving and permanent water prevention. The monitoring and application results show that the initial and perma- nent waterproof theory has provided an effective method for roadway driving and making it waterproof.
文摘Water security in Africa has never been as starkly highlighted as the countdown to Day Zero in Cape Town. South Africa, where becauseof an unprecedented drought, the entire city of about 4 million residents could be without water in July. Water restrictions for all residents are already in place and Day Zero has an activation date of July 9 (at the time of writing). If this catastrophe happens, it would make the famous tourist city that is frequently voted the world's most beautiful destination, earn another more dubious title that of the first major city in the world to ever run out of water.
基金supported by the National Natural Science Foundation of China (50879085)the Program for New Century Excellent Talents in University(NCET-07-0778)the Key Technology Research Project of Dynamic Environmental Flume for Ocean Monitoring Facilities (201005027-4)
文摘Compared with traditional real-time forecasting,this paper proposes a Grey Markov Model(GMM) to forecast the maximum water levels at hydrological stations in the estuary area.The GMM combines the Grey System and Markov theory into a higher precision model.The GMM takes advantage of the Grey System to predict the trend values and uses the Markov theory to forecast fluctuation values,and thus gives forecast results involving two aspects of information.The procedure for forecasting annul maximum water levels with the GMM contains five main steps:1) establish the GM(1,1) model based on the data series;2) estimate the trend values;3) establish a Markov Model based on relative error series;4) modify the relative errors caused in step 2,and then obtain the relative errors of the second order estimation;5) compare the results with measured data and estimate the accuracy.The historical water level records(from 1960 to 1992) at Yuqiao Hydrological Station in the estuary area of the Haihe River near Tianjin,China are utilized to calibrate and verify the proposed model according to the above steps.Every 25 years' data are regarded as a hydro-sequence.Eight groups of simulated results show reasonable agreement between the predicted values and the measured data.The GMM is also applied to the 10 other hydrological stations in the same estuary.The forecast results for all of the hydrological stations are good or acceptable.The feasibility and effectiveness of this new forecasting model have been proved in this paper.
文摘Hypertension, as the third cause of death, besides stroke and tuberculosis, amounts to 6.8 percent of the proportion of deaths at all ages in Indonesia. The prevalence of hypertension in Indonesia has reached 31.7 percent of the total adult population. Estimated, there are 76 percent of cases of hypertension in people who have not been diagnosed. Drinking enough ordinary water will help maximize the function of the body organs, in order to work optimally, so that the body metabolism will run well and normal. For smokers this amount shall be increased by half. The purpose of research was to know the effect of drinking water and other factors on the prevention of hypertension in working area Puskesmas Pasirkaliki Bandung. Design study was case control. The number of samples is 156 people, with a ratio of 1:1 (between cases and controls). Data were collected by interviewing. The bivariate analysis used chi square test, and multivariate analysis used logistic regression. The result of drinking enough ordinary water at least 6 cups a day contributes to prevent hypertension. For those who are still healthy, habit of drinking ordinary water is recommended at least 6 cups (1500 ml) per day. But for people who already have hypertension, heart and kidney diseases should be adjusted to the excretion organ.
文摘Under the circumstance that deep mining is increasingly vulnerable to underlying limestone water, accurate detection of floor failure depth ranges at a mining face becomes rather critical to coal mine production in safety. Underground borehole fiber optic sensing technology is combined with 2-D parallel electrical surveying to comprehensively monitor and analyze development laws of floor deformation and failure. Moreover, a working face 1022 in a mine of Huaibei Mining Area was taken, for example, introducing the layout of monitoring borehole and installation of relevant sensing units. Based on the stope progress of a working face, data related to strain and geoelectric fields were collected regularly to analyze relationships of field source variation characteristics and strata deformation failures. In this way, the development mechanism of the floor deformation failure can be revealed. As demonstrated by results, the depth failure of the floor at coal seam 10 is calculated to be 15 m, while its disturbance depth turns out to be 22 m. Due to advanced stress, concentrated stope load and post-mining pressure relief, the floor experienced elastic deformation, shear deformation and swelling deformation successively. Without a doubt, testing results obtained have scientific guiding significance for mines with similar geological conditions.