The Water and Energy transfer Processes in Cold Regions (WEP-COR) model is an improved version of the Water and Energy transfer Processes in Large basins (WEP-L) model that integrates a multi-layer frozen soil model to simulate the hydrological processes in cold regions and the heat fluxes at different depths of frozen soil. The temperature, water content, freezing depth of the soil, and daily discharge were simulated and compared with observations. The simulated and observed data were used to analyze the runoff flow components. The results showed that the WEP-COR model can effectively simulate the distributions of the soil temperature and water content. The average root mean squared errors of the temperature, unfrozen water content, total water content, and freezing depth of the soil were 1.21 °C, 0.035 cm3/cm3, 0.034 cm3/cm3, and 17.6 cm, respectively. The mean Nash–Sutcliffe efficiency and relative error of the daily discharge were 0.64 and 6.58%, respectively. Compared with the WEP-L model, the WEP-COR model simulated the discharge with higher accuracy, especially during the soil thawing period. This improvement was mainly due to the addition of the frozen soil mechanism. The WEP-COR model can provide support for agricultural and water resources management in cold regions.

To study the response of runoff to extreme changes in land use, the Soil and Water Assessment Tool (SWAT) model was used to construct historical, extreme, and future scenarios for several major landscape types in a permafrost region of northeastern China. The results show that the SWAT model is applicable in the Tahe River Basin; forestlands, shrublands, wetlands, and grasslands are the main land-use types in this basin, and the transfers among them from 1980–2015 have impacted runoff by less than 5%. Under extreme land use-change scenarios, the simulated runoff decreased from grasslands, to wetlands, shrublands, and finally, forestlands. The conversion of extreme land-use scenarios produces different hydrological effects. When forestland is converted to grassland, runoff increases by 25.32%, when forestland is converted to wetland, runoff increases by 13.34%, and the conversion of shrubland to forestland reduces runoff by 13.25%. In addition, the sensitivity of runoff to different land-use changes was much greater during flood seasons than in dry seasons. Compared to the reference year of 2015, the annual simulated runoff under the two future land-use scenarios (shrublands to forestlands and shrublands to wetland) was less. Also, both future land-use scenarios showed effects to decrease flooding and increased dryness, This study provided important insight into the integrated management of land use and water resources in the Tahe River Basin and the permafrost region of northeastern China.

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Photoacoustic computed tomography (PACT) based on a full-ring ultrasonic transducer array is widely used for small animal wholebody and human organ imaging, thanks to its high in-plane resolution and full-view fidelity. However, spatial aliasing in full-ring geometry PACT has not been studied in detail. If the spatial Nyquist criterion is not met, aliasing in spatial sampling causes artifacts in reconstructed images, even when the temporal Nyquist criterion has been satisfied. In this work, we clarified the source of spatial aliasing through spatiotemporal analysis. We demonstrated that the combination of spatial interpolation and temporal filtering can effectively mitigate artifacts caused by aliasing in either image reconstruction or spatial sampling, and we validated this method by both numerical simulations and in vivo experiments.