Sunflower is a critical oilseed crop that underpins global food security. As the world's largest exporter of sunflower oil, Ukraine produced 6.89 million tons in 2021, accounting for approximately one-third of global production. However, the ongoing Russia–Ukraine conflict has severely disrupted the local agricultural system, and the specific impacts on sunflower production dynamics remain unclear. To address this, we constructed a comprehensive monitoring framework by integrating Sentinel-1 Synthetic Aperture Radar (SAR) and Sentinel-2 optical imagery. First, we mapped annual sunflower cultivation distributions from 2019 to 2023 using an automated sample extraction method coupled with a Random Forest model, achieving an overall classification accuracy of 94.35%. Second, we implemented grid-based production prediction to capture fine-scale agricultural productivity heterogeneity. The results reveal a 49.5% decline in sunflower cultivation area between 2021 and 2022, accompanied by severe landscape fragmentation. Notably, the loss pattern exhibited a distinct “strip-like” distribution along the conflict frontline. Regarding production, while total output collapsed, the trend in unit yields diverged from the drastic reduction in cultivated areas, suggesting a potential shift in the agricultural production mode toward concentration. Finally, analysis based on multi-source indicators confirmed that farmland destruction, personnel loss, and water source damage were the drivers of agricultural decline in the region. These findings highlight the high vulnerability of agricultural systems under armed conflict and provide critical insights for post-conflict agricultural recovery and sustainable land use policymaking.

The wide-bandgap semiconductors represented by GaN have a broad application prospect because of their high service temperature and high switch frequency. Quad-Flat-No-Lead (QFN) Package is currently one of the mainstream packaging methods due to its low cost and high efficiency. However, the low reliability of QFN used in GaN devices is still a crucial problem caused by elevated temperatures and the thermal stress induced by the mismatch of coefficient of thermal expansion (CTE). Therefore, it is necessary to control the temperature inner the package and increase the mechanical property of the bonding layer. In this paper, the finite element method (FEM) with thermal-mechanical coupling is performed to optimize the reliability of the bonding layer by adopting sinter nano Cu and silver. Based on the conventional QFN package module, we tried to add different metallization on the bonding surface to decrease the influence of CTE mismatch. We should note that the Anand viscoplastic model was used in the materials of Sintered Ag and lead-free solder paste presented by SAC305, which were the most commonly used in die-attachment. The results showed that the utilization of nano copper/silver paste could hardly facilitate thermal performance although sintered Ag had excellent thermal conductivity. Since the Anand modules of Ag and SAC305 were different, there were some impacts on the stress distribution and deformation. During the bonding process, a large thermal stress generated between die-attachment layer and Package or the PCB. The die-attachment layer formed by nano Ag paste suffered the smaller thermal stress because its CTE is comparable to that of thermal pad. In terms of sintered Ag, the bonding layer generated more elastic strain. As the deformation recovered to initial stage, the stress decreased because of the elastic strain. And we also found that the Ag metallization could decreased the maximum stress of model at heating stage. But Ag metallization suffered larger thermal stress as the temperature decreased. The selection of connection materials and metallization are a crucial part of design the structure of electronic package. And this paper could provide a reference for optimize the package structure to further improve their reliability in future works.

Nano-metal sintering is a promising technology for the next generation of semiconductor packaging due to its positive effect on reliability enhancement. Compared with the silver sintering, copper-based sintering technique has more potential to be applied in die attachment field as its superiorities on lower cost, higher melting temperature without electromigration. In this study, Taguchi method is applied to study and analyze the effect of nano-/micro- particle ratio on sintering properties. Sintering temperature is also taken into account since it depends on the particle size a lot. The results show that both sintering temperature and nano-micro- ratio play significant role on influencing shear strength. The best combination is 300 nm with 1 um mixing (1:1) with over 35 MPa shear strength with 300°C sintering temperature. The fracture surface result shows that the crack propagated in the sintering body. Furthermore, the cross-section inspection reveals dense bonding and clearly sintering necking, and the porosity is lower than 12%. 227.8 W/m*K thermal conductivity and 6.0 uΩ·cm electrical resistivity are measured for the sample, which indicates the great potential for the packaging application in high power situation.