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To address problems including underestimation of heavy precipitation, rapid decay of synoptic systems and low computational efficiency in operational forecast of CMA-GFS V3.3, some key technologies related to physics and dynamics of the model are developed and applied.A suite of graupel-related microphysical processes is adopted in the cloud microphysics scheme to improve the forecast performance of heavy precipitation. These processes include graupel colliding with cloud water, ice crystals and snow, automatic conversions of ice crystals to graupel and snow to graupel, melting process of graupel to raindrop and sublimation process of graupel. In addition, the evaporation rate of cloud and rainwater is restricted, which can increase the liquid water content in warm areas and improve precipitation efficiency.In the convection parameterization scheme, the role of the sub-cloud environmental relative humidity to convection triggers is considered, and the unreasonable occurrence of convections in dry environment is suppressed. Also, the sensitivity of the entrainment rate of the convective updraft to the relative humidity outside the cloud is enhanced to weaken the convections in dry environment. At the same time, the quasi-equilibrium closure scheme is optimized to improve the accuracy in calculating cloud-base mass flux which is related to the convection intensity.To solve the problem of the mass loss in long time integration, a mass conservation correction method is introduced to the model dynamic framework. The method is developed to ensure the mass conservation by adjusting mass in each grid box according to different weight coefficients which are determined by the change of total atmospheric mass of the current time step relative to the previous step.In terms of computational efficiency, the two-dimensional reference profile algorithm is developed. Without losing calculation accuracy, the model integration time step is extended from 240 s to 300 s using the new profile instead of the original three-dimensional reference profile. Meanwhile, the PCSI method is adopted instead of the GCR method, which reduces the time consuming of solving Helmholtz equation. In addition, the radiation scheme and predictor-corrector algorithms are also optimized to improve the computational efficiency.Through the application of the above key technologies, the forecasting skills for weather pattern and precipitation of CMA-GFS are significantly improved. And its computational efficiency is increased by about 1/3, which meets operational time requirement for the model with 0.125° horizontal resolution. Based on the improved model and the research achievements in other aspects of the forecast system, CMA-GFS is upgraded to V4.0 with a significantly improved comprehensive performance.

Aiming at the problem that the non-stationary of airborne bistatic radar clutter reduces the performance of traditional clutter suppression algorithm, this paper first formulates airborne bistatic radar clutter model, and then analyzes the bistatic radar clutter characteristics in four typical combat scenarios. In addition, in order to reduce the computation burden of the STAP algorithm, a three-dimensional cross-beam clutter suppression algorithm is proposed, which uses the transformation matrix to convert the space-time two-dimensional data into azimuth-elevation-Doppler three-dimensional data. By eliminating auxiliary beam clutter data, only the main beam clutter data which plays a major role in dual-basis clutter suppression is retained to form a three-dimensional cross-beam for local adaptive clutter suppression. The proposed algorithm can greatly reduce the amount of calculation and the demand of training samples, while trying to ensure that the clutter suppression performance does not degrade. The effectiveness of the proposed algorithm is verified by analyzing the clutter suppression effect and computation amount of various algorithms in typical combat scenarios. Therefore, the algorithm has great potential in the applications of airborne bistatic and non-stationary clutter suppression.

In radar and sonar system, with regard to achieve high interference rejection and enhance target signal detection performance, adaptive beampattern synthesis with low sidelobe levels is desired. A new approach to beampattern synthesis with sidelobe control is developed. The essence of the presented method is to consider the application of spheroidal sequences to beampattern synthesis to alleviate the computational complexity. The presented technique represents a modification of the beampattern synthesis with sidelobe control of the prescribed threshold. The spheroidal sequences approach that characterises the out-of-sector angular regions is considered to alleviate the computational cost. The resulting beampattern synthesis approach is showed to be convex, and its second-order cone formulation is given that facilitates a computationally efficient way to implement the proposed beamformer with the help of the optimal software. Simulation results are given to demonstrate the effectiveness of the presented algorithm and to show the superiority to the state-of-the-art algorithm.

Curing agents for epoxy resin (EP) are one of the most important branches in the polymer materials field due to their enormous potential in many fields, but constructing them in a well‐controlled curing temperature remains challenging. Herein, a novel curing agent is constructed by the zirconium metal‐organic framework (UiO‐66) and [P4442]2[IDA] through an impregnation method. [P4442]2[IDA]@UiO‐66 is utilized as a functional nanofiller and curing agent to construct the [P4442]2[IDA]@UiO‐66/EP nanocomposites. The chemical structures of [P4442]2[IDA]@UiO‐66 were investigated by XRD, SEM, DSC, and TG characterizations. The various [P4442]2[IDA]@UiO‐66 with different loading amounts of [P4442]2[IDA] were used to investigate the curing behaviors of the EP‐51. The DSC results confirm that the curing temperature of the [P4442]2[IDA]@UiO‐66/EP is higher than that of [P4442]2[IDA]/EP. In addition, the kinetic parameters and the activation energy of the curing reaction were acquired according to the fitting of Kissinger equation and Ozawa equation. The drying time of [P4442]2[IDA]@UiO‐66/EP system at 40 °C was enhanced 17 times compare to that of [P4442]2[IDA]/EP system. This study opens new avenues for the rational design of EP nanocomposites by employing ionic liquids@MOFs composite materials as curing agent for wide engineering applications. [ABSTRACT FROM AUTHOR]

A novel strategy was proposed to improve the performance of gas separation in nano-materials, by fabricating a core–shell structure out of the basic ionic liquid ([Emim]2[IDA]) and zeolitic imidazolate framework (ZIF-8). The [Emim]2[IDA]/ZIF-8 exhibits a remarkable CO2 adsorption capacity of 14 cm3 g−1 at 298 K and 20 kPa, the ideal selectivity of CO2/N2 is as high as 104 and CO2/CH4 is 348 at 298 K and 100 kPa, which are much higher than the CO2 adsorption capacity (4.3 cm3 g−1) and the selectivity (SCO2/N2 = 7.4, SCO2/CH4 = 2.7) of ZIF-8. This work could pave the way for designing advanced nanostructures tailored for gas separation. [ABSTRACT FROM AUTHOR]

The application of high internal phase emulsions (HIPEs) in food, medicine, and cosmetics has been greatly limited due to lack of anti-ultraviolet and anti-oxidant structures. Herein, a series of rodlike TiO2/lignin nanoparticles were prepared by using TiO2 as a hardcore and modified lignin as a coating and dispersion stabilizer. SEM images show that samples have well dispersity and present a rodlike morphology. However, the aspect ratio (AR) values of samples have significant differences due to the presence of different contents of carboxyl and hydroxyl groups in lignin derivatives. Subsequently, their emulsification was predicted by the spreading coefficient and adsorption energy. The results show that the higher AR value of samples, the lower dispersion coefficient and the higher adsorption energy, indicating better emulsification activity. The emulsification test suggests that 0.16 wt % TiO2/arginine-modified lignin with highest AR value could stabilize HIPEs with 90 vol % oil phase volume due to a strong bridging effect. Existing literature shows that the dosage of nanoparticles in HIPEs is the lowest value of other biomass emulsifiers, which shows good biocompatibility. Meanwhile, the oil phase volume of HIPEs in this work is the highest value of other HIPEs prepared with biomass-based particles, which means that these HIPEs would have a higher load capacity for active substances and longer shelf life due to the low water content. The antioxidant experiment shows that TAML could completely clear the •OH, and the scavenging efficiency is 17 times that of pure TiO2. The UV-protection test indicates that the sun protection factor value of TAML reached 149.5, which is the highest value of other lignin-based sunscreen particles. This work provides a method for the preparation of high-performance and multifunctional emulsifiers, which expands the application of lignin and enhances the application potential of HIPEs in medicine, food, cosmetics, and other fields. [ABSTRACT FROM AUTHOR]

A layered metal‐organic framework Zn‐TPN was designed and fabricated by solvothermal reaction. The crystal structure was a lamellar structure, and the unique coordination pattern provided Lewis acid sites that could be employed as efficient catalytic sites. Zn‐TPN displayed a satisfactory catalytic effect for Knoevenagel condensation of malononitrile and benzaldehyde. At 75 °C, the conversion rate reached 96.96 % basing on the acidic sites after 1 hour, and it showed ideal catalytic activities for Knoevenagel condensation containing various aldehydes. Zn‐TPN could be utilized as a promising heterogeneous catalyst for Knoevenagel condensation. [ABSTRACT FROM AUTHOR]

The rational integration of multi-functional components with metal-organic frameworks (MOFs) to form MOF-based catalysts can often afford enhanced catalytic activity for specific reactions. Herein, we propose a novel strategy for the synthesis of hierarchically porous MOFs (e.g., MIL-101)-encapsulated N-doped nanocarbon (CN@MIL) by controlled pyrolysis of ionic liquids@MIL-101 precursors (ILs@MIL). The obtained CN@MIL composites not only possess abundant enlarged mesopores, but also show multi-active sites without the sacrifice of their structure stability. The CN@MIL can efficiently facilitate the mass transfer of substrates, exhibiting excellent catalytic performance in the synthesis of cyclic carbonates from epoxides and CO2 under mild and co-catalyst-free conditions (i.e., 90 °C and ambient pressure of CO2). Furthermore, the multi-active Lewis acid sites and nucleophilic sites (Br ions) as well as the strong affinity of catalysts toward CO2 also contribute to the excellent catalytic activity of the CN@MIL. This study might open a new avenue for the rational design of MOF-based composites by employing ILs@MOF as precursors for advanced heterogeneous catalysis. [ABSTRACT FROM AUTHOR]