A rock burst disaster not only destroys the pit facilities and results in economic loss but it also threatens the life of the miners. Pillar rock burst has a higher frequency of occurrence in the pit compared to other...A rock burst disaster not only destroys the pit facilities and results in economic loss but it also threatens the life of the miners. Pillar rock burst has a higher frequency of occurrence in the pit compared to other kinds of rock burst. Understanding the cause, magnitude and prevention of pillar rock burst is a significant undertaking. Equations describing the bending moment and displacement of the rock beam in asymmetric mining have been deduced for simplified asymmetric beam-pillar systems. Using the symbolic operation software MAPLE 9.5 a catastrophe model of the dynamic failure of an asymmetric rock-beam pillar system has been established. The differential form of the total potential function deduced from the law of conservation of energy was used for this deduction. The critical conditions and the initial and final positions of the pillar during failure have been given in analytical form. The amount of elastic energy released by the rock beam at the instant of failure is determined as well as. A diagrammatic form showing the pillar failure was plotted using MATLAB software. This plot contains a wealth of information and is important for understanding the behavior during each deformation phase of the rock-beam pillar system. The graphic also aids in distinguishing the equivalent stiffness of the rock beam in different directions.展开更多
This paper summarizes the results of energy simulation analysis to determine the effectiveness of building characteristics in reducing electrical energy consumption in residential buildings （conditioned and unconditi...This paper summarizes the results of energy simulation analysis to determine the effectiveness of building characteristics in reducing electrical energy consumption in residential buildings （conditioned and unconditioned） and commercial buildings （office ＆ hotel） in Egypt. Specifically, the impact on building envelope performance is investigated for different strategies such as window size, glazing type and building construction for two geographical locations in Egypt. This paper also studies the energy savings in residential and nonresidential buildings for different lighting power densities （LPD）, energy input ratios （EIR）, set point temperatures （SPT） and heating, ventilation, and air conditioning （I-WAC） systems. The study shows certain findings of practical significance, e.g. that a window-to-wall ratio of 0.20 and reasonably shaded windows lower the total annual electricity use for nonresidential buildings by more than 20% in the two Egyptian locations.展开更多
Pulsed electric field is an innovative method for non-thermal food processing. The effects of pulsed electric field on cell disintegration and mass transfer in sugar beet were studied. Sugar beet slices were treated b...Pulsed electric field is an innovative method for non-thermal food processing. The effects of pulsed electric field on cell disintegration and mass transfer in sugar beet were studied. Sugar beet slices were treated by various Field strengths （0.5-6 kV cm^-1）, capacity of capacitors （0.5, 8 and 32 μF） and pulse numbers （1-100 pulses）. The cell disintegration index and energy input for each treated sample was evaluated. The results showed that the cell membrane of PEF （Pulsed Electric Field） treated samples using 2 kV cm^-1, 8 μF after 20 pulses, and 3 kV cm1, 8 μF after 10 pulses were rapidly disintegrated in less than 1 min. Most important parameters during cell permeabilization were the total energy input followed by field strength. Energy efficiency index was defined as cell disintegration index per energy input unit. The maximum efficiency index was achieved using 2 kV cm^-1, 8 μF after 5 pulses. Comparison between PEF pretreatment and thermal method showed that large amount of sugar may be extracted after PEF pretreatment using field strength of 2 Kv cm^-1, 8μF in less than 10 min at ambient temperature. In.addition, the consumed energy for thermal treatment was approximately 20 to 50 times more than PEF pretreatment. Optimizing the field conditions in PEF treatment is an important factor to achieve high amount of sugar extraction from sugar beet.展开更多
The energy budget of the magnetosphere-ionosphere (MI) system during 1998-2008 was examined by using Akasofu's epsilon function. The results showed that 1) the yearly average rate of solar wind energy input into t...The energy budget of the magnetosphere-ionosphere (MI) system during 1998-2008 was examined by using Akasofu's epsilon function. The results showed that 1) the yearly average rate of solar wind energy input into the MI system was 4.51 GGJ (GGJ=1018 J), while the yearly average total dissipation was 4.30 GGJ; 2) the energy partitioning in the ring current and polar region was 56%:44%; 3) the energy input and dissipation processes continuously proceeded both in storm-substorm events and less disturbed intervals, suggesting the significant contribution of slow but long-lasting energy process during the less disturbance periods to the total energy budget. In addition, we found in this study an interesting phenomenon "self-adjustment ability" of the MI system which behaves just like a water reservoir. During solar active years, the input energy is more than the dissipated energy, implying that a portion of the input energy is not immediately released, but is stored in the magnetosphere. On the other hand, during less active years, the dissipated energy is more than the input energy, implying that the previously stored energy makes up for the energy input shortage in this period.展开更多
基金Projects Y2005-A03 supported by the Natural Science Foundation of Shandong Province of ChinaG04D15 by the Educational Committee ofShandong Province of China
文摘A rock burst disaster not only destroys the pit facilities and results in economic loss but it also threatens the life of the miners. Pillar rock burst has a higher frequency of occurrence in the pit compared to other kinds of rock burst. Understanding the cause, magnitude and prevention of pillar rock burst is a significant undertaking. Equations describing the bending moment and displacement of the rock beam in asymmetric mining have been deduced for simplified asymmetric beam-pillar systems. Using the symbolic operation software MAPLE 9.5 a catastrophe model of the dynamic failure of an asymmetric rock-beam pillar system has been established. The differential form of the total potential function deduced from the law of conservation of energy was used for this deduction. The critical conditions and the initial and final positions of the pillar during failure have been given in analytical form. The amount of elastic energy released by the rock beam at the instant of failure is determined as well as. A diagrammatic form showing the pillar failure was plotted using MATLAB software. This plot contains a wealth of information and is important for understanding the behavior during each deformation phase of the rock-beam pillar system. The graphic also aids in distinguishing the equivalent stiffness of the rock beam in different directions.
文摘This paper summarizes the results of energy simulation analysis to determine the effectiveness of building characteristics in reducing electrical energy consumption in residential buildings （conditioned and unconditioned） and commercial buildings （office ＆ hotel） in Egypt. Specifically, the impact on building envelope performance is investigated for different strategies such as window size, glazing type and building construction for two geographical locations in Egypt. This paper also studies the energy savings in residential and nonresidential buildings for different lighting power densities （LPD）, energy input ratios （EIR）, set point temperatures （SPT） and heating, ventilation, and air conditioning （I-WAC） systems. The study shows certain findings of practical significance, e.g. that a window-to-wall ratio of 0.20 and reasonably shaded windows lower the total annual electricity use for nonresidential buildings by more than 20% in the two Egyptian locations.
文摘Pulsed electric field is an innovative method for non-thermal food processing. The effects of pulsed electric field on cell disintegration and mass transfer in sugar beet were studied. Sugar beet slices were treated by various Field strengths （0.5-6 kV cm^-1）, capacity of capacitors （0.5, 8 and 32 μF） and pulse numbers （1-100 pulses）. The cell disintegration index and energy input for each treated sample was evaluated. The results showed that the cell membrane of PEF （Pulsed Electric Field） treated samples using 2 kV cm^-1, 8 μF after 20 pulses, and 3 kV cm1, 8 μF after 10 pulses were rapidly disintegrated in less than 1 min. Most important parameters during cell permeabilization were the total energy input followed by field strength. Energy efficiency index was defined as cell disintegration index per energy input unit. The maximum efficiency index was achieved using 2 kV cm^-1, 8 μF after 5 pulses. Comparison between PEF pretreatment and thermal method showed that large amount of sugar may be extracted after PEF pretreatment using field strength of 2 Kv cm^-1, 8μF in less than 10 min at ambient temperature. In.addition, the consumed energy for thermal treatment was approximately 20 to 50 times more than PEF pretreatment. Optimizing the field conditions in PEF treatment is an important factor to achieve high amount of sugar extraction from sugar beet.
基金supported by the National Natural Science Foundation of China (Grant Nos. 40931056, 40874089)the National Basic Research Program of China ("973" Project) (Grant Nos. 2008CB425704)
文摘The energy budget of the magnetosphere-ionosphere (MI) system during 1998-2008 was examined by using Akasofu's epsilon function. The results showed that 1) the yearly average rate of solar wind energy input into the MI system was 4.51 GGJ (GGJ=1018 J), while the yearly average total dissipation was 4.30 GGJ; 2) the energy partitioning in the ring current and polar region was 56%:44%; 3) the energy input and dissipation processes continuously proceeded both in storm-substorm events and less disturbed intervals, suggesting the significant contribution of slow but long-lasting energy process during the less disturbance periods to the total energy budget. In addition, we found in this study an interesting phenomenon "self-adjustment ability" of the MI system which behaves just like a water reservoir. During solar active years, the input energy is more than the dissipated energy, implying that a portion of the input energy is not immediately released, but is stored in the magnetosphere. On the other hand, during less active years, the dissipated energy is more than the input energy, implying that the previously stored energy makes up for the energy input shortage in this period.
