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The detection of vehicle targets in wide-area Synthetic Aperture Radar (SAR) images is crucial for real-time reconnaissance tasks and the widespread application of remote sensing technology in military and civilian fields. However, existing detection methods often face difficulties in handling large-scale images and achieving high accuracy. In this study, we address the challenges of detecting vehicle targets in wide-area SAR images and propose a novel method that combines coarse-grained judgment with fine-grained detection to overcome these challenges. Our proposed vehicle detection model is based on YOLOv5, featuring a CAM attention module, CAM-FPN network, and decoupled detection head, and it is strengthened with background-assisted supervision and coarse-grained judgment. These various techniques not only improve the accuracy of the detection algorithms, but also enhance SAR image processing speed. We evaluate the performance of our model using the Wide-area SAR Vehicle Detection (WSVD) dataset. The results demonstrate that the proposed method achieves a high level of accuracy in identifying vehicle targets in wide-area SAR images. Our method effectively addresses the challenges of detecting vehicle targets in wide-area SAR images, and has the potential to significantly enhance real-time reconnaissance tasks and promote the widespread application of remote sensing technology in various fields.

High-efficiency warmth retention materials are urgently needed by human living in extremely cold environment to maintain their health and physical function. However, most existing fibrous warmth retention materials suffer from large weight, inefficient warm retention performance, and poor antibacterial ability. Here, we propose an innovative strategy to construct ultrafine fibrous sponges with interlaced crimped-fiber architecture by direct electrospinning technology. The stable three-dimensional (3D) network structures assemble from tangly curled ultrafine fibers, endowing the obtained sponges with ultralight characteristics (4.5 mg cm−3), robust elastic resilience (nearly full recovery from 100-cycle compressive deformations), and low thermal conductivity (24.1 mW m−1 K−1). Moreover, the in situ doping of chlorhexidine and fluoropolymer enables the sponges with efficient and durable antibacterial performance after washing processes (antibacterial rate up to 95.6% after 10 recycle washing experiments). This work opens a new way for the design of 3D fibrous materials with remarkable antibacterial performance for various fields.

Warmth retention equipment for personal cold protection is highly demanded in freezing weather; however, most present warmth retention materials suffer from high thermal conductivity, weak mechanical properties, and strong flammability, resulting in serious security risks. Herein, we report a facile strategy to fabricate nano-/microfibrous sponges with superelasticity, robust flame retardation, and effective warmth retention performance via direct electrospinning. The three-dimensional fluffy sponges with low volume density and high porosity are constructed by accurately regulating the relative humidity; meanwhile, the mechanically robust polyamide-imide nanofibers with high limit oxygen index (LOI) are innovatively introduced to improve the structural stability and flammability of the nano-/microfibrous sponges. Strikingly, the developed nano-/microfibrous sponges exhibit ultralight characteristics (6.9 mg cm-3), superelasticity (∼0% plastic deformation after 100 compression tests), effective flame retardant with LOI of 26.2%, and good heat preservation ability (thermal conductivity of 24.6 mW m-1 K-1). This work may shed light on designing superelastic and flame-retardant warmth retention materials for various applications.

Health risks in an extremely cold environment make warm retention equipment highly desirable. However, creating materials with a high warm retention performance and robust mechanical property to durably prevent against the harsh conditions is highly challenging. Herein, we report on a one-step and facile strategy to fabricate stretchable and superelastic fibrous sponges by creating unique "stiff-soft" polymer networks within fibers and bonding architecture among fibers. The premise of this design is that stiff polystyrene can endow materials with rigidity and soft polyurethane can absorb energy during mechanical deformation. Benefiting from this systematic tailoring for the polymer and assembling networks, the resultant fibrous sponges exhibit a unique tensile recovery property, a large breaking elongation of 70%, and an outstanding resilience for resisting 100 cyclic compressions with 50% strain under -50 °C. Moreover, the fibrous sponges possess dramatic characteristics of high porosity (∼99.31%), ultralight property (volume density = 7.68 mg cm

In this study, the whole fraction low temperature coal tar (LTCT) was used as raw material, a series of hydrodeasphaltenization (HDAs) experiments were conducted in an isothermal trickle bed reactor, then the kinetic equation of the reaction was established in gPROMS software and the parameters were estimated. The trickle bed reactor model was established and the effects of operating conditions on HDAs reaction and catalyst effective factors were analyzed. The reactor temperature was varied from 623 to 683 K, the hydrogen pressure from 6 to 12 MPa, keeping constant hydrogen-to-oil volume ratio at 1000:1, liquid hourly space velocity at 0.5 h−1. The results showed that the relative error between the experimental and the simulated results were less than ± 5%, which proved that the model had good applicability; the activation energy was 149.8 kJ mol−1, the pre-exponential factor was 633,832, the reaction order was 1.347, and the order of hydrogen was 2.33. The higher activation energy indicated that the HDAs was difficult to occur compared with the reaction in crude oil. And the high hydrogen order indicated that the pressure had a significant influence on the reaction rate. However, the high temperature and low pressure would reduce the effective factor of the catalyst. The reason may be that the large diffusion limitation and reaction heat of asphaltenes lead to a large difference in reaction rates between the catalyst surface and the tunnel of pores under high temperature. This study could contribute to a more in-depth understanding of the features and rules of LTCT HDAs, and also provide a useful model for reactor design, operation and control.