高光条件下视频人像处理方法研究

目的针对高光条件下导致的视频人像模糊、细节缺失的情况,研究高光条件下的视频人像的处理方法,改善视频中高光人像的视觉效果。方法详细分析了高光条件下视频人像存在的问题,给出了高光视频人像处理流程图,阐述了普通监控拍摄模式下和红外监控模式下高光人像处理方法。具体处理方法 :在人像视频中挑取成像质量较好、光照影响较小、尺寸较大的关键帧图像,将人像剪裁出合适的尺寸。在空域内用曲线调节、伽马校正,在频域内用高通滤波、同态滤波等方法分别对彩色高光人像和灰度高光人像进行增强处理,然后进行人像重建、合成。结果面对高光人像细节丢失这种普遍情况,在对人像重建、合成前,对原始高光人像进行增强处理是有必要的。相对于直接对原始高光人像,先对人像进行高光抑制,再进行重建、合成处理效果更好。在处理方法上,频域内的高通滤波锐化加强效果更好。相对于彩色视频人像,红外视频人像丢失了色彩,在高通滤波前进行曲线调节或伽马校正是有必要的。在某些情况下,灰度图像的处理效果比彩色图像处理效果更好,将彩色图像转换为灰度图像然后再进行重建处理也是可行的方法。结论正确处理高光人像能够为视频侦查提供更准确线索,文中所提方法能够改善高光人像视觉效果。

Experimental study of hypervapotron under conditions of high heat flux

In the light of the needs to develop high-performance heat transfer component for nation-level large-scale scientific projects of China,a hypervapotron experimental platform with supply of heat flux 1 10 MW m-2 was established.With this platform,the multiphase flow and heat transfer phenomena on the surface of triangular fin when the subcooled water flowed through were observed and measured with the planar laser induced fluorescence(PLIF) and high-speed photography techniques.The temperature contour on the slice plane of fin symmetry was measured and the heat flux contour was processed based on gradient computation.It is confirmed that:1) PLIF with high-speed photography is very powerful technique to investigate the multiphase flow of hypervapotron quantitatively;2) evaporation is the primary way in heat transfer mechanism of hypervapotron flow under the condition of high heat flux.The techniques and results obtained will provide useful reference in the R&D of hypervapotron technology in China.

Physical conditions for sources radiating a cosh-Gaussian model beam

Based on the coherence theory of diffracted optical field and the model for partially coherent beams,analytical expressions for the cross-spectral density and the irradiance spectral density in the far zone are derived,respectively.Utilizing the theoretical model of radiation from secondary planar sources,the physical conditions for sources generating a cosh-Gaussian(CHG) beam are investigated.Analytical results demonstrate that the parametric conditions strongly depend on the coherence property of sources.When almost coherence property is satisfied in the source plane,the conditions are the same as those for fundamental Gaussian beams;when partial coherence or almost incoherence property is satisfied in the spatial source plane,the conditions are the same as those for Gaussian-Schell model beams.The results also indicate that the variance of cosine parameters has no influence on the conditions.Our results may provide potential applications for some investigations such as the modulations of cosh-Gaussian beams and the designs of source beam parameters.

Efficient solar fuel production with a high-pressure CO_(2)-captured liquid feed

We demonstrated an efficient solar photovoltaic-powered electrochemical CO_(2) reduction device with a high-pressure CO_(2)-captured liquid feed.In an“air-to-barrel”picture,this device holds promise to avoid both high-temperature gaseous CO_(2) regeneration and high energy-cost gas product separation steps,while these steps are necessary for devices with a gaseous CO_(2) feed.To date,solar fuel production with a CO_(2)-saturated liquid feed suffers from high over-potential to suppress the hydrogen evolution reaction and consequently,low solar-to-chemical(STC)energy conversion efficiency.Here,we presented a distinct high-pressure operando strategy,i.e.,we took extra advantage of the high pressure in catalyst synthesis besides in the period of the CO_(2) reduction reaction(CO_(2)RR).The power of this strategy was demonstrated by a proof-of-concept device in which a representative copper catalyst was first synthesized in operando in a high-pressure(50 bar)CO_(2)-saturated KHCO3 solution,and then this high-pressure CO_(2)-captured liquid was converted to solar fuel using the operando synthesized Cu catalyst.This Cu catalyst achieved 95%CO_(2)RR selectivity at the recorded low potential of−0.3 V vs.RHE enabled by the combination of operando facet engineering and oxide derivation.Furthermore,this device achieved a record-high STC efficiency of 21.6%under outdoor illumination,superior to other CO_(2)-saturated liquid-fed devices,and compared favorably to gaseous CO_(2)-fed devices.