Energy consumption is a major factor influencing climate change. Low-carbon strategies can be defined from carbon (C) footprint and ecological pressure caused by energy consumption. We hypothesized that this should be done at the regional and city levels because factors controlling C footprints vary with location and time, yet there is actually little knowledge at local levels. Here, we mapped the C emissions and footprint of 11 cities in the Zhejiang Province of China, a rapidly growing area of about 57 million inhabitants, which is representative of the strong economic growth in China. The C footprint is expressed as the land surface necessary to adsorb C emissions. We studied spatio-temporal evolution of C footprints from 2005 to 2015 using the center of gravity method. Results show that total annual C emissions due to energy consumption in Zhejiang increased by 40.83 million tons (55.8%
Particle settling in stratified fluids is widespread in chemical and pharmaceutical processes, and how to effectively regulate the particle velocity is the key to optimizing the above process technology.
The phenomenon of near-wall particle settling in a stratified fluid is an emerging topic in the field of multiphase flow, and it is also widely found in nature and engineering applications. In stratified fluids, particle settling characteristics are affected by the physical and chemical properties of the upper and lower fluids, the particle size, the particle density, and the initial sedimentation conditions. In this study, the main objective is to determine the effect of liquid viscosity and particle density on the detaching process, and the trajectory and velocity of near-wall settling particles in stratified fluids. The inertia and velocity of the particle had a greater impact on the tail pinch-off model in low-viscosity lower fluids; that is, the lower the inertia and velocity, the more apparent the order between deep and shallow seal pinch-off. In comparison, in high-viscosity lower fluids, the tail pinch-off models of different inertia and velocity particles were similar. In terms of particle trajectory, the transverse motion of the particle in the low-viscosity lower fluid exhibited abrupt changes; that is, the particles moved away from the wall suddenly, whereas in the high-viscosity lower fluid, the transverse movement was gradual. Due to the existence of the wall, the transverse motion direction of the free settling particles in the stratified fluid, which is determined by the rotation direction of the particles, changed to a direction away from the wall regardless of the particle rotation direction. This transverse movement also caused the particle settling velocity to drop suddenly or its rising rate to decrease, this is because part of the energy was used for transverse motion and to increase the transverse velocity. In our study, the near-wall settling of particles in a stratified fluid mainly affected the particle trajectory; that is, forced movement away from the wall, thus changing the particle velocity. This characteristic provides a new approach to manipulate particles away from the wall.
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