Search

Two-dimensional flow of the pulsed co-flow jet (CFJ) and the influence of the pulsed parameters on the lift and power consumption are investigated numerically. Firstly, the jet channel of traditional CFJ airfoil is improved. The stall margin is increased by 3° compared with the corresponding traditional CFJ airfoil, and the lift is increased, while the drag is reduced significantly. Then, the influence of the pulsed parameters, such as the pulse waveform, including sinusoidal and rectangular waves, the duty cycle, and the pulse frequency on the lift and power consumption are presented and analyzed in detail. It is concluded that, compared with the steady CFJ, the pulsed CFJ possesses much better ability in suppressing separation and can improve the lift characteristics significantly with limited cost of power consumption. For example, at an angle of attack of 20° flow separation occurs severely, when the steady CFJ is adopted; however, the airflow becomes fully attached on the upper airfoil, when the rectangular pulsed CFJ is employed. As a result, the lift corresponding to the rectangular wave is higher than that of the sinusoidal wave. The results also indicate that the lower duty cycle and pulse frequency can lead to the higher lift but with more power consumption.

The rapid development of urbanization has caused many ecological issues and greatly threatened the sustainable development of human society. The construction of ecological security patterns (ESPs) offers an effective way to balance ecological conservation and urbanization. This study aimed to take the highly urbanized city of Shenzhen, China, as a study area to construct an urban ESP and put forward suggestions for the urban development of ecological security. Ecological sources were identified through the Habitat Quality module in the InVEST model, and ecological corridors, strategic ecological nodes, and stepping-stone patches were extracted based on the minimum cumulative resistance (MCR) model. These elements together constituted the ESP. In particular, with the results of the continuous decline in the overall habitat quality, this study identified ten ecological sources with superior habitat quality, mainly distributed in rural woodlands, in urban green land, and in forest park patches. An optimized pattern for Shenzhen City with one axis, three belts, and four zones is proposed, with the study area divided into an ecological preservation zone, a limited development zone, an optimized development zone, and a key development zone. Moreover, forty-five ecological corridors were extracted and graded into three levels, presenting a spatial pattern of one axis and three belts. The appropriate widths of these ecological corridors were suggested to be between 30 and 60 m in Shenzhen City. In addition, we identified twenty-five ecological nodes, sixteen ecological fracture points, and sixteen stepping stones to improve the maintenance and construction of the ecological corridor network. More generally, this study demonstrates a scientific approach to identifying ESPs based on habitat quality, and can serve as a reference for the planning of urban ecological function regionalization.

Coal is China’s main energy, and this situation in the future in a long period of time is unlikely to have fundamental changes. As an underground activity, coal mining inevitably causes local damage and pollution to underground water cut system due to improper application of coal mining technology. And a large number of mine drainage, not only need to spend a lot of drainage costs, increase the cost of coal production, but also waste very valuable water resources. In this paper, based on the water - coal, on the basis of coordination development, through big data analysis methods, proposes the establishment process of coal mining and mine water quality, and the whole life cycle of the coal - water coordination development precision control technology system, through a series of research on the laws of the evolution of time and space and nonlinear multiobjective model building and simulation development plan, research and development of the evaluation method of mine water resource utilization efficiency and benefit, help to realize the coordinated development of the coal - water control in whole life cycle of technology. So as to realize the exploitation and utilization of mine drainage and turn waste into treasure, it can not only relieve the tight situation of water supply in coal mines, but also reduce the environmental pollution caused by coal mining to the mining areas and surrounding cities, and realize the unity of economic and environmental benefits.

Quantum resetting protocols allow a quantum system to be sent to a state in the past by making it interact with quantum probes when neither the free evolution of the system nor the interaction is controlled. We experimentally verify the simplest non-trivial case of a quantum resetting protocol, known as the $\mathcal{W}_4$ protocol, with five superconducting qubits, testing it with different types of free evolutions and target-probe interactions. After projection, we obtained a reset state fidelity as high as $0.951$, and the process fidelity was found to be $0.792$. We also implemented 100 randomly-chosen interactions and demonstrated an average success probability of $0.323$ for $|1\rangle$ and $0.292$ for $|-\rangle$, experimentally confirmed the nonzero probability of success for unknown interactions; the numerical simulated values are about $0.3$. Our experiment shows that the simplest quantum resetting protocol can be implemented with current technologies, making such protocols a valuable tool in the eternal fight against unwanted evolution in quantum systems., 9 pages, 6 figures, 1 table + Supplementary Materials

Quantum computing has seen tremendous progress in the past years. Due to the implementation complexity and cost, the future path of quantum computation is strongly believed to delegate computational tasks to powerful quantum servers on cloud. Universal blind quantum computing (UBQC) provides the protocol for the secure delegation of arbitrary quantum computations, and it has received significant attention. However, a great challenge in UBQC is how to transmit quantum state over long distance securely and reliably. Here, we solve this challenge by proposing and demonstrating a resource-efficient remote blind qubit preparation (RBQP) protocol with weak coherent pulses for the client to produce, using a compact and low-cost laser. We demonstrate the protocol in field, experimentally verifying the protocol over 100-km fiber. Our experiment uses a quantum teleportation setup in telecom wavelength and generates $1000$ secure qubits with an average fidelity of $(86.9\pm1.5)\%$, which exceeds the quantum no-cloning fidelity of equatorial qubit states. The results prove the feasibility of UBQC over long distances, and thus serving as a key milestone towards secure cloud quantum computing., 11 pages, 9 figures

To effectively protect shallow groundwater and to evaluate the environmental impact of groundwater, we set up a monitoring network of 30 monitoring wells and collected 11 water samples from the wells during the rainy and dry seasons. Hydrochemical characteristics of the shallow groundwater were identified with the Piper and Gibbs diagrams. Groundwater quality was assessed with the single standard index method and the entropy-weighted water quality index. Finally, we used a numerical simulation of the impact of the power plant operation on the groundwater environment. The average abundance of the major ions in groundwater from the dry to the wet season occurred in the following orders: Ca2+ > Na+ > Mg2+ > K+ for cations and HCO3− > SO42− > Cl− for anions. The shallow groundwater usually has elevated hardness and alkalinity values comparison with the standard values. The dominant hydrochemical facies of the groundwater is the HCO3–Ca type. Rock weathering is likely to be the dominant process that controls the groundwater chemical composition. Groundwater in the study area is suitable for drinking under ordinary conditions, according to the single standard index method and the entropy-weighted water quality index. However, the groundwater quality has been influenced by anthropogenic activities (including near the west Ash Yard and Huangji Sunaba). Numerical modeling shows that leakage during abnormal operating conditions is of limited extent within the boundary of the simulated area and does not enter into the Yangtze River. Overall, it is necessary to carry out effective anti-seepage and pollution control measures to ensure that shallow groundwater is not contaminated.