“边界工作”是研究新闻从业者如何通过特定的话语策略来维护自身职业地位与合法性的经典理论框架。然而,ChatGPT和Sora等技术的开发应用表明生成式人工智能已具备多模态内容生产能力,套用“边界工作”理论中的扩张(expansion)、驱逐(ex...“边界工作”是研究新闻从业者如何通过特定的话语策略来维护自身职业地位与合法性的经典理论框架。然而,ChatGPT和Sora等技术的开发应用表明生成式人工智能已具备多模态内容生产能力,套用“边界工作”理论中的扩张(expansion)、驱逐(expulsion)和自主性保护(protection of autonomy)三条阐释维度已不足以说明生成式人工智能参与新闻生产的种种实践进路。受布尔迪厄“场域”理论启发,哥伦比亚大学教授伊亚尔(Gil Eyal)提出基于关系视角的“边界域”(Boundary zone)理论。本文认为,新闻“边界域”为毗邻新闻业的其他社会场域中的行动者提供了活动的机会空间,技术行动者和职业行动者获得平等的实践身份,新的社会场域由此得以诞生。媒体主导的新闻场域和科技公司主导的技术场域之间的“边界域”成为未来新闻实践的主体网络。展开更多
Electrochemical N_(2) reduction reaction(eNRR) over Cu-based catalysts suffers from an intrinsically low activity of Cu for activation of stable N_(2) molecules and the limited supply of N_(2) to the catalyst due to i...Electrochemical N_(2) reduction reaction(eNRR) over Cu-based catalysts suffers from an intrinsically low activity of Cu for activation of stable N_(2) molecules and the limited supply of N_(2) to the catalyst due to its low solubility in aqueous electrolytes.Herein,we propose phosphorus-activated Cu electrocatalysts to generate electron-deficient Cu sites on the catalyst surface to promote the adsorption of N_(2) molecules.The eNRR system is further modified using a gas diffusion electrode(GDE) coated with polytetrafluoroethylene(PTFE) to form an effective three-phase boundary of liquid water-gas N_(2)-solid catalyst to facilitate easy access of N_(2) to the catalytic sites.As a result,the new catalyst in the flow-type cell records a Faradaic efficiency of 13.15% and an NH_(3) production rate of 7.69 μg h^(-1) cm^(-2) at-0.2 V_(RHE),which represent 3.56 and 59.2 times increases from those obtained with a pristine Cu electrode in a typical electrolytic cell.This work represents a successful demonstration of dual modification strategies;catalyst modification and N_(2) supplying system engineering,and the results would provide a useful platform for further developments of electrocatalysts and reaction systems.展开更多
This paper presents a numerical study on the aerodynamics loss reduction characteristics after the leading-edge(LE) optimization in a low-pressure turbine linear cascade. The LE was optimized with a simple and practic...This paper presents a numerical study on the aerodynamics loss reduction characteristics after the leading-edge(LE) optimization in a low-pressure turbine linear cascade. The LE was optimized with a simple and practical method of "Class Function/Shape Function Transformation Technique"(CST). The simulation conditions, covering the whole working range, were independently determined by incidence, Reynolds number and Mach number. Quantitative loss analyses were carried out with a loss breakdown method based on volumetric integration of entropy production rates. To understand the reason of loss reduction, the local sources at different operating points were identified with entropy production rates. The results showed that LE optimization with the CST method played a positive role in decreasing the total losses, and the working range with lower loss was extended. The profile loss and the endwall loss were significantly reduced by the LE optimization, which were also verified to be the major causes of the total loss reduction by loss breakdown. The decrease of profile loss can be attributed to the boundary layer near the LE region and the boundary layer of downstream at off-design incidence. The reduction mostly came from the pressure side at negative incidence, while came from the suction side at the positive incidence. The endwall loss was decreased markedly about 2.5%–5% by the LE optimization at the incidence of-12°, which was 1% at the incidence of 12°. The mechanism for the endwall loss reduction at different incidences was different from each other. At negative incidence, the LE optimization diminished the corner separation vortex on the pressure side. While at positive incidence, the benefits came from three aspects, i.e., reduced suction LE separation bubbles close to the endwall, reduced passage vortex strength, and weakened shear process between passage vortex and trailing shed vortex. The loss of the downstream zone was relatively lower than that of the profile losses and the endwall losses. The effect 展开更多
文摘“边界工作”是研究新闻从业者如何通过特定的话语策略来维护自身职业地位与合法性的经典理论框架。然而,ChatGPT和Sora等技术的开发应用表明生成式人工智能已具备多模态内容生产能力,套用“边界工作”理论中的扩张(expansion)、驱逐(expulsion)和自主性保护(protection of autonomy)三条阐释维度已不足以说明生成式人工智能参与新闻生产的种种实践进路。受布尔迪厄“场域”理论启发,哥伦比亚大学教授伊亚尔(Gil Eyal)提出基于关系视角的“边界域”(Boundary zone)理论。本文认为,新闻“边界域”为毗邻新闻业的其他社会场域中的行动者提供了活动的机会空间,技术行动者和职业行动者获得平等的实践身份,新的社会场域由此得以诞生。媒体主导的新闻场域和科技公司主导的技术场域之间的“边界域”成为未来新闻实践的主体网络。
基金supported by the Climate Change Response Project (NRF-2019M1A2A2065612)the Brainlink Project (NRF2022H1D3A3A01081140)+3 种基金the NRF-2021R1A4A3027878 and the No. RS-2023-00212273 funded by the Ministry of Science and ICT of Korea via National Research Foundationresearch funds from Hanhwa Solutions Chemicals (1.220029.01)UNIST (1.190013.01)supported by the Institute for Basic Science (IBS-R019-D1)。
文摘Electrochemical N_(2) reduction reaction(eNRR) over Cu-based catalysts suffers from an intrinsically low activity of Cu for activation of stable N_(2) molecules and the limited supply of N_(2) to the catalyst due to its low solubility in aqueous electrolytes.Herein,we propose phosphorus-activated Cu electrocatalysts to generate electron-deficient Cu sites on the catalyst surface to promote the adsorption of N_(2) molecules.The eNRR system is further modified using a gas diffusion electrode(GDE) coated with polytetrafluoroethylene(PTFE) to form an effective three-phase boundary of liquid water-gas N_(2)-solid catalyst to facilitate easy access of N_(2) to the catalytic sites.As a result,the new catalyst in the flow-type cell records a Faradaic efficiency of 13.15% and an NH_(3) production rate of 7.69 μg h^(-1) cm^(-2) at-0.2 V_(RHE),which represent 3.56 and 59.2 times increases from those obtained with a pristine Cu electrode in a typical electrolytic cell.This work represents a successful demonstration of dual modification strategies;catalyst modification and N_(2) supplying system engineering,and the results would provide a useful platform for further developments of electrocatalysts and reaction systems.
基金sponsored by the Project NO.51576037 supported by National Natural Science Foundation of China (NSFC)
文摘This paper presents a numerical study on the aerodynamics loss reduction characteristics after the leading-edge(LE) optimization in a low-pressure turbine linear cascade. The LE was optimized with a simple and practical method of "Class Function/Shape Function Transformation Technique"(CST). The simulation conditions, covering the whole working range, were independently determined by incidence, Reynolds number and Mach number. Quantitative loss analyses were carried out with a loss breakdown method based on volumetric integration of entropy production rates. To understand the reason of loss reduction, the local sources at different operating points were identified with entropy production rates. The results showed that LE optimization with the CST method played a positive role in decreasing the total losses, and the working range with lower loss was extended. The profile loss and the endwall loss were significantly reduced by the LE optimization, which were also verified to be the major causes of the total loss reduction by loss breakdown. The decrease of profile loss can be attributed to the boundary layer near the LE region and the boundary layer of downstream at off-design incidence. The reduction mostly came from the pressure side at negative incidence, while came from the suction side at the positive incidence. The endwall loss was decreased markedly about 2.5%–5% by the LE optimization at the incidence of-12°, which was 1% at the incidence of 12°. The mechanism for the endwall loss reduction at different incidences was different from each other. At negative incidence, the LE optimization diminished the corner separation vortex on the pressure side. While at positive incidence, the benefits came from three aspects, i.e., reduced suction LE separation bubbles close to the endwall, reduced passage vortex strength, and weakened shear process between passage vortex and trailing shed vortex. The loss of the downstream zone was relatively lower than that of the profile losses and the endwall losses. The effect
