The porous medium has an important effect on hydrate formation.In this paper,the formation process and the gas storage capacity of the methane hydrate were investigated with A-type zeolite and Sodium Dodecyl Sulfate (...The porous medium has an important effect on hydrate formation.In this paper,the formation process and the gas storage capacity of the methane hydrate were investigated with A-type zeolite and Sodium Dodecyl Sulfate (SDS) existing in the system.The results show that A-type zeolite can influence methane hydrate formation.At the temperature of 273.5 K and pressure of 8.3 MPa,the distilled water with A-type zeolite can form methane hydrate with gaseous methane in 12 hours.The formation process of the system with A-type zeolite was quite steady and the amount of A-type zeolite can influence the gas storage capacity significantly.The adding of A-type zeolite with 0.067 g·(g water)-1 into 2×10-3 g·g-1 SDS-water solution can increase the gas storage capacity,and the maximum increase rate was 31%.Simultaneously the promotion effect on hydrate formation of 3A-type zeolite is much more obvious than that of 5A-type zeolite when the water adding amounts are 0.033 g·g-1 and 0.067 g·g-1 at the experimental conditions.展开更多
Cereal grains are stored to preserve the product from storing to consuming without any quality loss. The choice of the most suitable and economical store has great importance on storage period of cereals under conside...Cereal grains are stored to preserve the product from storing to consuming without any quality loss. The choice of the most suitable and economical store has great importance on storage period of cereals under consideration of climate conditions, types of grain and transportation facility. The aim of present study was to give information about different cereal storage methods and discuss the most preferable technique for stock keepers. There are five main storage methods for the cereals, i.e., bulk storage, storage in underground pit, storage in bags, storage in sheds and storage in silos. Each has many advantages and disadvantages. Grains are usually preserved as bulk stack in horizontal stores. Nowadays, the storage underground is not preferred in cereal industry. For long-term storage period, cereals are unfavorable when stored as bulk in bags. Location, moisture content and sufficient ventilation are important factors for cereals stored in sheds. The most preferred storage technique in plants is to keep the products in silos. Steel and galvanized silos are the most common ones when compared with the others. In recent years, convention of storage techniques for grains has been advanced with the innovations, such as aeration, refrigerated storage, modified atmospheric storage and hermetic storage systems.展开更多
Rangeland systems play an important role in ecological stabilization and the terrestrial carbon cycle in arid and semiarid regions. However, little is known about the vegetative carbon dynamics and climatic and topog-...Rangeland systems play an important role in ecological stabilization and the terrestrial carbon cycle in arid and semiarid regions. However, little is known about the vegetative carbon dynamics and climatic and topog- raphical factors that affect vegetative carbon stock in these rangelands. Our goal was to assess vegetative carbon stock by examining meteorological data in conjunction with NDVI (normalized difference vegetation index) time se- ries datasets from 2001-2012. An improved CASA (Carnegie Ames Stanford Approach) model was then applied to simulate the spatiotemporal dynamic variation of vegetative carbon stock, and analyze its response to climatic and topographical factors. We estimated the vegetative carbon stock of rangeland in Gansu province, China to be 4.4×10^14 gC, increasing linearly at an annual rate of 9.8×10^11 gC. The mean vegetative carbon density of the whole rangeland was 136.5 gC m-2. Vegetative carbon density and total carbon varied temporally and spatially and were highly associated with temperature, precipitation and solar radiation. Vegetative carbon density reached the maximal value on elevation at 2500-3500 m, a slope of 〉30°and easterly aspect. The effect of precipitation, tem- perature and solar radiation on the vegetative carbon density of five rangeland types (desert and salinized meadow, steppe, alpine meadow, shrub and tussock, and marginal grassland in the forest) depends on the acquired quantity of water and heat for rangeland plants at all spatial scales. The results of this study provide new evidence for ex- plaining spatiotemporal heterogeneity in vegetative carbon dynamics and responses to global change for rangeland vegetative carbon stock, and offer a theoretical and practical basis for grassland agriculture management in arid and semiarid regions.展开更多
基金Supported by the National Natural Science Foundation of China (50876107), the National Basic Research Program of China (2009CB219504), NSFC-Guangdong Union Foundation (NSFC-U0733033) and CAS Program (KGCX2-YW-805).
文摘The porous medium has an important effect on hydrate formation.In this paper,the formation process and the gas storage capacity of the methane hydrate were investigated with A-type zeolite and Sodium Dodecyl Sulfate (SDS) existing in the system.The results show that A-type zeolite can influence methane hydrate formation.At the temperature of 273.5 K and pressure of 8.3 MPa,the distilled water with A-type zeolite can form methane hydrate with gaseous methane in 12 hours.The formation process of the system with A-type zeolite was quite steady and the amount of A-type zeolite can influence the gas storage capacity significantly.The adding of A-type zeolite with 0.067 g·(g water)-1 into 2×10-3 g·g-1 SDS-water solution can increase the gas storage capacity,and the maximum increase rate was 31%.Simultaneously the promotion effect on hydrate formation of 3A-type zeolite is much more obvious than that of 5A-type zeolite when the water adding amounts are 0.033 g·g-1 and 0.067 g·g-1 at the experimental conditions.
文摘Cereal grains are stored to preserve the product from storing to consuming without any quality loss. The choice of the most suitable and economical store has great importance on storage period of cereals under consideration of climate conditions, types of grain and transportation facility. The aim of present study was to give information about different cereal storage methods and discuss the most preferable technique for stock keepers. There are five main storage methods for the cereals, i.e., bulk storage, storage in underground pit, storage in bags, storage in sheds and storage in silos. Each has many advantages and disadvantages. Grains are usually preserved as bulk stack in horizontal stores. Nowadays, the storage underground is not preferred in cereal industry. For long-term storage period, cereals are unfavorable when stored as bulk in bags. Location, moisture content and sufficient ventilation are important factors for cereals stored in sheds. The most preferred storage technique in plants is to keep the products in silos. Steel and galvanized silos are the most common ones when compared with the others. In recent years, convention of storage techniques for grains has been advanced with the innovations, such as aeration, refrigerated storage, modified atmospheric storage and hermetic storage systems.
基金National Natural Science Foundation of China(30960264 and 31160475)Science and technology program of Gansu province(1107RJYA058)+1 种基金open project of Key Laboratory of Grassland Ecosystem(Gansu Agricultural University),Ministry of Education(CYZS–2011014)Fund of technology innovation commemorated Sheng Tongsheng in Gansu Agricultural University(GSAU-STS-1304 and GSAU-STS-1505)
文摘Rangeland systems play an important role in ecological stabilization and the terrestrial carbon cycle in arid and semiarid regions. However, little is known about the vegetative carbon dynamics and climatic and topog- raphical factors that affect vegetative carbon stock in these rangelands. Our goal was to assess vegetative carbon stock by examining meteorological data in conjunction with NDVI (normalized difference vegetation index) time se- ries datasets from 2001-2012. An improved CASA (Carnegie Ames Stanford Approach) model was then applied to simulate the spatiotemporal dynamic variation of vegetative carbon stock, and analyze its response to climatic and topographical factors. We estimated the vegetative carbon stock of rangeland in Gansu province, China to be 4.4×10^14 gC, increasing linearly at an annual rate of 9.8×10^11 gC. The mean vegetative carbon density of the whole rangeland was 136.5 gC m-2. Vegetative carbon density and total carbon varied temporally and spatially and were highly associated with temperature, precipitation and solar radiation. Vegetative carbon density reached the maximal value on elevation at 2500-3500 m, a slope of 〉30°and easterly aspect. The effect of precipitation, tem- perature and solar radiation on the vegetative carbon density of five rangeland types (desert and salinized meadow, steppe, alpine meadow, shrub and tussock, and marginal grassland in the forest) depends on the acquired quantity of water and heat for rangeland plants at all spatial scales. The results of this study provide new evidence for ex- plaining spatiotemporal heterogeneity in vegetative carbon dynamics and responses to global change for rangeland vegetative carbon stock, and offer a theoretical and practical basis for grassland agriculture management in arid and semiarid regions.