Agricultural tridimensional pollution （AtriP） has multi-directional and complicated chains. Circular economy is found to be an efficient mechanism that can help control AtriP. The application of three circular econo...Agricultural tridimensional pollution （AtriP） has multi-directional and complicated chains. Circular economy is found to be an efficient mechanism that can help control AtriP. The application of three circular economic modes in agriculture and its related industries call not only interdict the AtriP chains in different stages and different directions, but also produce greater ecological, social and economical returns with less input. Nevertheless, it is a complicated systematic engineering to construct and implement effective circular economic modes to bring AtriP under control, and it depends not only on the support of the relevant technology system, but also on the supports of the relevant policies and law systems.展开更多
An investigation is presented on the performance of a small-scale solar power and heating system with short parabolic trough collectors(PTCs). The steady-state model of the short PTCs is evaluated with outside experim...An investigation is presented on the performance of a small-scale solar power and heating system with short parabolic trough collectors(PTCs). The steady-state model of the short PTCs is evaluated with outside experiments. The model mainly contains the heat loss of the receiver, the peak optical efficiency and the incident angle factor consisting of incident angle modifier and end loss. It is found that the end loss effect is essential in this model when the length of the PTCs is less than 48 m, especially in the winter. The standard deviation of the steady-state model is 1.4%. Moreover, the potential energy efficiency ratio of the solar power and heating system is considerably larger than the coefficient of performance(COP) of general air-source heat pumps, and increases with the decrease of the condensation temperature. An overall system efficiency of 49% can be reached. Lastly,the existence of a water storage tank improves the flexibility of heating the building, and the volume of the water storage tank decreases with the increase of the heating water temperature.展开更多
Mathematics is rigorous and abstract, which is easy to make pupils feel boring and divorced from the reality of life. If teachers can dig out the materials related to the students' daily life in the daily classroo...Mathematics is rigorous and abstract, which is easy to make pupils feel boring and divorced from the reality of life. If teachers can dig out the materials related to the students' daily life in the daily classroom teaching, so that the children can feel that the content of mathematics is not boring numbers and tasteless calculations, but a living discipline that can be seen and felt by the children and is closely connected with daily life, the students can be more interested in the study of mathematics, thus obtaining a sense of success in the study and greatly benefiting the foundation of studious mathematics. This paper discusses the creation of life situations, skillful design of life problems, design of games and activities closely related to life, and design of practical operations related to life.展开更多
文摘Agricultural tridimensional pollution （AtriP） has multi-directional and complicated chains. Circular economy is found to be an efficient mechanism that can help control AtriP. The application of three circular economic modes in agriculture and its related industries call not only interdict the AtriP chains in different stages and different directions, but also produce greater ecological, social and economical returns with less input. Nevertheless, it is a complicated systematic engineering to construct and implement effective circular economic modes to bring AtriP under control, and it depends not only on the support of the relevant technology system, but also on the supports of the relevant policies and law systems.
基金the Special Research Fund for the National Key Research and Development Program of China(No.2016YFB0901300)
文摘An investigation is presented on the performance of a small-scale solar power and heating system with short parabolic trough collectors(PTCs). The steady-state model of the short PTCs is evaluated with outside experiments. The model mainly contains the heat loss of the receiver, the peak optical efficiency and the incident angle factor consisting of incident angle modifier and end loss. It is found that the end loss effect is essential in this model when the length of the PTCs is less than 48 m, especially in the winter. The standard deviation of the steady-state model is 1.4%. Moreover, the potential energy efficiency ratio of the solar power and heating system is considerably larger than the coefficient of performance(COP) of general air-source heat pumps, and increases with the decrease of the condensation temperature. An overall system efficiency of 49% can be reached. Lastly,the existence of a water storage tank improves the flexibility of heating the building, and the volume of the water storage tank decreases with the increase of the heating water temperature.
文摘Mathematics is rigorous and abstract, which is easy to make pupils feel boring and divorced from the reality of life. If teachers can dig out the materials related to the students' daily life in the daily classroom teaching, so that the children can feel that the content of mathematics is not boring numbers and tasteless calculations, but a living discipline that can be seen and felt by the children and is closely connected with daily life, the students can be more interested in the study of mathematics, thus obtaining a sense of success in the study and greatly benefiting the foundation of studious mathematics. This paper discusses the creation of life situations, skillful design of life problems, design of games and activities closely related to life, and design of practical operations related to life.
