A new experiment was made on the developing of bed separations and mining subsidence from Tangshan T2192 working face by equivalent materials simulation.The overburden deformation and the developing of bed separations...A new experiment was made on the developing of bed separations and mining subsidence from Tangshan T2192 working face by equivalent materials simulation.The overburden deformation and the developing of bed separations with working face advanc- ing was simulated by a new model.The results show that the maximum value of bed separations moved forward gradually along with the working face advancing;the maxi- mum value of bed separations is 0.31～0.50 times of mining thickness.The key strata have a great influence upon surface subsidence during the overburden movement process.The mechanics parameters of new experiment are fitted with results in fields perfectly.展开更多
Analyzing observations of wintertime air temperature in both indoor and outdoor surroundings in Kunming, a city lying in low latitudes, characteristics of temperature and humidity have been studied for the interior of...Analyzing observations of wintertime air temperature in both indoor and outdoor surroundings in Kunming, a city lying in low latitudes, characteristics of temperature and humidity have been studied for the interior of rooms facing north-south under different weather conditions. Significant warming effect has been identified in terms of lowest and daily-mean indoor temperature in the area of Kunming. The heating amplitude ranges from 7.7C to 10.0C and from 4.6C to 5.8C for the interior part of rooms facing the south and from 4.6C to 7.0C and from 1.3C to 4.4C for the interior part of rooms facing the north, respectively for the two elements. The highest air temperature is higher indoor than outdoor for rooms facing the south, but otherwise is usually true for rooms facing the north. Additional findings point out that buildings not only help maintain relatively warm indoor temperature but delay its variation. The diurnal cycle of temperature indoor is smaller and ranges by 40% ~ 48% for south-facing rooms, and by 20% ~ 30% for north-facing rooms, than outdoor, and the highest temperature is about 2 hours late inside the room than outside. It shows how inertly indoor temperature varies. The work also finds that relative humidity is less indoor in southward rooms than in northward ones and difference is the largest on fine days but the smallest when it is overcast. For the diurnal variation, the indoor relative humidity is large at nighttime with small amplitude but small during daytime with large amplitude. The above-presented results can be served as scientific foundation for more research on climate in low-latitude cities and rational design of urban architectures.展开更多
针对变风量(varied air volume,VAV)空调系统运行过程中,温湿度控制回路之间存在强耦合效应,同时,考虑到VAV空调系统具有非线性、大时滞、大惯性等动态特性,传统的控制方法很难对其实现精确的控制,提出了基于滑模控制的VAV空调房间温湿...针对变风量(varied air volume,VAV)空调系统运行过程中,温湿度控制回路之间存在强耦合效应,同时,考虑到VAV空调系统具有非线性、大时滞、大惯性等动态特性,传统的控制方法很难对其实现精确的控制,提出了基于滑模控制的VAV空调房间温湿度解耦控制系统,分别设计了解耦环节和滑模控制方案。MATLAB仿真结果显示,所提方法不仅能有效消除温湿度控制回路间的耦合效应,且相较于传统的PID控制策略,在滑模控制策略下温湿度控制系统具有更小的超调、更快的响应速度、更短的调节时间,且控制过程更加平缓稳定,一定程度上改善了整个系统的控制性能。展开更多
基金The National Natural Science Funds Committee(50174035)
文摘A new experiment was made on the developing of bed separations and mining subsidence from Tangshan T2192 working face by equivalent materials simulation.The overburden deformation and the developing of bed separations with working face advanc- ing was simulated by a new model.The results show that the maximum value of bed separations moved forward gradually along with the working face advancing;the maxi- mum value of bed separations is 0.31～0.50 times of mining thickness.The key strata have a great influence upon surface subsidence during the overburden movement process.The mechanics parameters of new experiment are fitted with results in fields perfectly.
文摘Analyzing observations of wintertime air temperature in both indoor and outdoor surroundings in Kunming, a city lying in low latitudes, characteristics of temperature and humidity have been studied for the interior of rooms facing north-south under different weather conditions. Significant warming effect has been identified in terms of lowest and daily-mean indoor temperature in the area of Kunming. The heating amplitude ranges from 7.7C to 10.0C and from 4.6C to 5.8C for the interior part of rooms facing the south and from 4.6C to 7.0C and from 1.3C to 4.4C for the interior part of rooms facing the north, respectively for the two elements. The highest air temperature is higher indoor than outdoor for rooms facing the south, but otherwise is usually true for rooms facing the north. Additional findings point out that buildings not only help maintain relatively warm indoor temperature but delay its variation. The diurnal cycle of temperature indoor is smaller and ranges by 40% ~ 48% for south-facing rooms, and by 20% ~ 30% for north-facing rooms, than outdoor, and the highest temperature is about 2 hours late inside the room than outside. It shows how inertly indoor temperature varies. The work also finds that relative humidity is less indoor in southward rooms than in northward ones and difference is the largest on fine days but the smallest when it is overcast. For the diurnal variation, the indoor relative humidity is large at nighttime with small amplitude but small during daytime with large amplitude. The above-presented results can be served as scientific foundation for more research on climate in low-latitude cities and rational design of urban architectures.
文摘针对变风量(varied air volume,VAV)空调系统运行过程中,温湿度控制回路之间存在强耦合效应,同时,考虑到VAV空调系统具有非线性、大时滞、大惯性等动态特性,传统的控制方法很难对其实现精确的控制,提出了基于滑模控制的VAV空调房间温湿度解耦控制系统,分别设计了解耦环节和滑模控制方案。MATLAB仿真结果显示,所提方法不仅能有效消除温湿度控制回路间的耦合效应,且相较于传统的PID控制策略,在滑模控制策略下温湿度控制系统具有更小的超调、更快的响应速度、更短的调节时间,且控制过程更加平缓稳定,一定程度上改善了整个系统的控制性能。
