Institutional Repository of GuangZhou Institute of Energy Conversion, CAS
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Western Light-Key Laboratory Cooperative Research Cross-Team Project of Chinese Academy of Sciences[xbzg-zdsys-202309]
No full textHighly active metal-acid bifunctional B-doped radial channel silica supported Ni2P for efficient hydrodeoxygenation performance
No full textUpgrading bio-oil into high-quality hydrocarbon fuel through hydrodeoxygenation (HDO) is highly desirable. Here we describe a method for fabricating a Ni2P metal-acid bifunctional catalyst (Ni2P/RCSN-B) supported on B-doped radial channels silica by a facile anion-assisted hydrothermal method. The results showed that the doped B was entered into the skeleton of RCSN to form the trigonally and tetrahedrally coordinated B species, providing the adjustable acid sites, which is responsible for the high target methylcyclohexane (MCH) product selectivity. And the radial channel pore structure promotes the efficient exposure of active sites, accelerates the mass transfer and leads to highly dispersed small Ni2P particles. Importantly, the kinetics study proved a high reaction constant for the constructed Ni2P/RCSN-B catalyst as compared to that of Ni2P supported on traditional SiO2 support, indicating the important role of the radial channel pore structure on shortening the reaction time. Benefit from the optimized acidity, rapid mass transfer and highly dispersed small Ni2P particles, Ni2P/RCSN-B achieved superior m-cresol HDO performance with HDO activity reaching 96.5 % and the selectivity to MCH reaching 91.5% within 1 h. There is no doubt that the combination of Ni2P and RCSN-B opens up a new idea for preparing high performance HDO catalysts
Resilience and dynamism: Innovative modeling of ecological group dynamics in urban landscapes
No full textEnhancing urban ecological resilience can promote sustainable and eco-friendly urban development by reducing environmental risks and vulnerabilities. However, current studies rarely offered ecological resilience assessment method along with an understanding of the coevolution mechanisms. In this study, we selected Guangzhou as the study area to create a dynamics model to diagnose the coevolution mechanism, and quantify ecological resilience according to the depiction of the basin of attribution. The results showed that 1) there were 535 ecological patches covering an area of 121,628 ha and featuring 1229 edges and 11 ecological groups. 2)The northern and eastern regions showed relatively high closeness and betweenness centralities, however, straightness centrality was lower in these areas; the ecological edges were presented lower connectivity in the northern and southern regions. 3) By using nonlinear dynamic equation, the origin state of each group increased toward the equilibrium point E3 suggested a declining trend in ecological sustainability under current conditions. The ecological resilience was decreased from Group 8 to Group 5. This research will help to understand the coevolution mechanism of the urban system for giving practical suggestions
A new frequency domain method to solve the potential flow problem
No full textThe potential flow theory is a reliable tool widely-used in ocean engineering to solve the fluid hydrodynamic problems such as the wave hydrodynamic problems. The Rankine source and its image about the seabed is often chosen as the Green's function to solve the potential flow problems for its simple form, easy singular-integral treatment and few boundary conditions in the boundary integral equations. However, traditionally, the boundary element method based on it is only executed in the time domain by time stepping technique which requires lots of computation due to the time domain form of the damping zone's boundary condition. To apply this Green's function in frequency domain, this paper derived a parameterized frequency-domain formula for the boundary condition of the damping zone, and successfully applied the Rankine source and its image about the seabed in frequency domain. This paper's work possesses a great potential to promote the efficiency in solving the potential flow problems
Experimental investigation on the initial pressure gain of pulse detonation cycle in a millimeter-scale spiral channel by using a Tesla turbine
No full textAlthough research interest in pressure gain combustion remains high, information on the deflagration-to-detonation transition (DDT) process in actual multiple-cycle pulse detonation combustors is sparse, especially in terms of initial pressure studies, a crucial parameter in design and operation of such combustors. To develop microscale detonation combustion technology and gain a better understanding of the impact of initial pressure, an experimental study on flame acceleration of hydrogen-oxygen premixed gas is conducted using a micro spiral channel with a Tesla turbine at the outlet, which can realize precise initial pressure regulation in an open-ended pulse detonation combustor. The initial pressure consists of turbine wind pressure (p(T)) and intake residual pressure (p(ir)). p(T) increases the back pressure at combustor's outlet, and p(ir) is derived from the channel static pressure and flow velocity during the gas intake phase by bringing the ignition timing close to the moment when the solenoid valve closes. The flames are recorded by high-speed photography and the flame propagation characteristics under different initial pressures are compared. Results demonstrate that different combinations of p(ir) and p(T) yield three distinct DDT modes (Mode1: low p(ir) boolean AND low p(T); Mode2: low p(ir) boolean AND high p(T); Mode3: high p(ir) boolean AND any p(T)), with p(ir) significantly outperforming p(T) in shortening DDT distance (L-DDT, Mode3 < Mode2 < Mode1) and mitigating the detonation wave velocity deficit (DWVD, Mode3 < Mode2 <= Mode1). High-pressure intake and timely ignition after valve closure (to trigger Mode3) is a very efficient way to generate detonation waves, which could be an ideal operation method for microscale pulse-detonation-based devices with hydrogen energy
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