The correct method used in forest soil respiration measurement by Li-6400 is a premise of data quality control. According to the study in a larch plantation, collars should be inserted at 12 hours in advance to effici...The correct method used in forest soil respiration measurement by Li-6400 is a premise of data quality control. According to the study in a larch plantation, collars should be inserted at 12 hours in advance to efficiently reduce the influence of CO2 spring-out.Moreover, collar insertion depth substantially affected soil respiration measurement, i.e. when collar was shallowly inserted into soil,transversal gas diffusion and the CO2 re-spring-out caused by unstable collars in the measurement could lead to overestimating soil respiration rate; however, when collar was deeply inserted into soil, root respiration decline caused by root-cut and the most active respiratory of the surface soil separated by the inserted collars could lead to underestimating soil respiration rate. Furthermore, an error less than 5% could be guaranteed in typical sunny day if the target [CO2] was set to the mean value of ambient [CO2] in most time of the day, but it should be carefully set in early morning and late afternoon according to changing ambient [CO2]. This protocol of measurement is useful in real measurement.展开更多
In this paper, we present an analysis of energy and exergy utilization in the residential sector of Cameroon by considering the sectoral energy and exergy flows for the years of 2001-2010. Exergy analysis of Cameroon ...In this paper, we present an analysis of energy and exergy utilization in the residential sector of Cameroon by considering the sectoral energy and exergy flows for the years of 2001-2010. Exergy analysis of Cameroon residential sector utilisation indicates a less efficient picture than that obtained by the energy analysis. Cooking stands out as the most inefficient end use in the Cameroon’s residential sector. In 2010, the energy and exergy efficiency are determined and were respectively 58.74% and 22.63%. Energy and exergy flows diagrams for the overall efficiencies of Cameroon residential sector are illustrated and a comparison with the residential sector of other countries is also done. To carry out this study, a survey of 250 households was conducted and the sharing of the end uses of energy was done and data were gathered.展开更多
The present paper is based upon the fact that if an object is part of a highly stable oscillating system, it is possible to obtain an extremely precise measure for its mass in terms of the energy trapped in the system...The present paper is based upon the fact that if an object is part of a highly stable oscillating system, it is possible to obtain an extremely precise measure for its mass in terms of the energy trapped in the system, rather than through a ratio between force and acceleration, provided such trapped energy can be properly measured. The subject is timely since there is great interest in Metrology on the establishment of a new electronic standard for the kilogram. Our contribution to such effort includes both the proposal of an alternative definition for mass, as well as the description of a realistic experimental system in which this new definition might actually be applied. The setup consists of an oscillating type-II superconducting loop subjected to the gravity and magnetic fields. The system is shown to be able to reach a dynamic equilibrium by trapping energy up to the point it levitates against the surrounding magnetic and gravitational fields, behaving as an extremely high-Q spring-load system. The proposed energy-mass equation applied to the electromechanical oscillating system eventually produces a new experimental relation between mass and the Planck constant.展开更多
基金National Natural Science Foundation of China (30300271),Program of Key Basic Research from Ministry of Science and Technology (2004CCA02700) and Sina-Japan cooperation project on larch forest study.
文摘The correct method used in forest soil respiration measurement by Li-6400 is a premise of data quality control. According to the study in a larch plantation, collars should be inserted at 12 hours in advance to efficiently reduce the influence of CO2 spring-out.Moreover, collar insertion depth substantially affected soil respiration measurement, i.e. when collar was shallowly inserted into soil,transversal gas diffusion and the CO2 re-spring-out caused by unstable collars in the measurement could lead to overestimating soil respiration rate; however, when collar was deeply inserted into soil, root respiration decline caused by root-cut and the most active respiratory of the surface soil separated by the inserted collars could lead to underestimating soil respiration rate. Furthermore, an error less than 5% could be guaranteed in typical sunny day if the target [CO2] was set to the mean value of ambient [CO2] in most time of the day, but it should be carefully set in early morning and late afternoon according to changing ambient [CO2]. This protocol of measurement is useful in real measurement.
文摘In this paper, we present an analysis of energy and exergy utilization in the residential sector of Cameroon by considering the sectoral energy and exergy flows for the years of 2001-2010. Exergy analysis of Cameroon residential sector utilisation indicates a less efficient picture than that obtained by the energy analysis. Cooking stands out as the most inefficient end use in the Cameroon’s residential sector. In 2010, the energy and exergy efficiency are determined and were respectively 58.74% and 22.63%. Energy and exergy flows diagrams for the overall efficiencies of Cameroon residential sector are illustrated and a comparison with the residential sector of other countries is also done. To carry out this study, a survey of 250 households was conducted and the sharing of the end uses of energy was done and data were gathered.
文摘The present paper is based upon the fact that if an object is part of a highly stable oscillating system, it is possible to obtain an extremely precise measure for its mass in terms of the energy trapped in the system, rather than through a ratio between force and acceleration, provided such trapped energy can be properly measured. The subject is timely since there is great interest in Metrology on the establishment of a new electronic standard for the kilogram. Our contribution to such effort includes both the proposal of an alternative definition for mass, as well as the description of a realistic experimental system in which this new definition might actually be applied. The setup consists of an oscillating type-II superconducting loop subjected to the gravity and magnetic fields. The system is shown to be able to reach a dynamic equilibrium by trapping energy up to the point it levitates against the surrounding magnetic and gravitational fields, behaving as an extremely high-Q spring-load system. The proposed energy-mass equation applied to the electromechanical oscillating system eventually produces a new experimental relation between mass and the Planck constant.
