实现LED照明的自由曲面透镜设计

为在特定平面上实现所需照明,从而满足各类LED照明系统的要求,通过透镜的第一面球面和第二面自由曲面的两次折射实现LED的配光设计.根据给出的LED辐射特性和所需实现的照明面上的能量分布,并预先定义透镜球面的结构参量,可得到一组一阶偏微分方程,数值差分求解直接求得透镜的自由曲面.光源采用发光面积1×1 mm2朗伯体发光的LED,视角180°,由自由曲面透镜得到的各种形状照明面的模拟均匀性皆接近90%,且能量利用率高于98%,编程解一阶偏微分方程组的计算时间少于20 s.     

均匀液滴的形成机理及实验研究

 在均匀液滴O₂(¹Δ)发生器的研制过程中,发生器中液流受到外界扰动后,扰动沿着液流表面呈指数增长,最终导致液流破段成液滴。在液滴的形成过程中,各种参数的改变都将对液流的状态产生影响,最终影响O₂(¹Δ)发生器的总体性能。分别从理论和实验两部分对液滴的形成过程进行了对比分析:理论部分论述了液滴形成的理论依据及在发生器中,外界扰动频率、液流喷射流速的改变对扰动增长率的影响及影响趋势;实验部分以成像的方式着重分析了在相同条件下,分别改变扰动频率、液流喷射流速,液滴流的状态及趋势。实验结合理论,寻求可控参数范围,为均匀液滴发生器的液流研究提供依据。     

Analysis on dynamics of a population model with predator–prey-dependent functional response

We consider a reaction–diffusion population model with predator–prey-dependent functional response. Firstly, we discuss the conditions which ensure the model has a unique positive constant solution. Secondly, we investigate the dynamical properties of the model, including the large time behaviors of the nonconstant solutions and the local and the global asymptotic stability of the positive constant solution.     

一类紧Fuzzy测度序列的淡收敛

经典测度的弱收敛和淡收敛在经典概率论等随机数学理论中有着很重要的作用。在局部紧Hausdorff空间中首次引入了一类紧Fuzzy 测度序列的淡收敛的概念,得到了它的等价形式及一些性质,推广了相应的经典结果。     

Fatou's identity and Lebesgue's convergence theorem

The classical Fatou lemma for bounded sequences of nonnegative integrable functions is represented as an equality. A similar result is stated for measure convergent sequences. Neither result requires a uniform integrability assumption. For the latter a converse is proven. Two extensions of Lebesgue's convergence theorem are presented.

     

Supercritical CO2 extraction of emodin and physcion from Polygonum cuspidatum and subsequent isolation by semipreparative chromatography

Emodin and physcion are abundant anthraquinone compounds found in the traditional Chinese medicinal herb Polygonum cuspidatum Sied. et Zucc. In this paper, emodin and physcion were successfully extracted with supercritical CO2 plus ethanol modifier after the extraction conditions were optimized with uniform design-sequential optimization. Results showed that the ethanol modifier concentration was the main factor for the effective extraction of the emodin. The optimal extraction condition was obtained: 20 MPa, 30 degrees C, and 95% ethanol, at which the yields of emodin and physcion were 0.616 and 0.178 g/100 g, respectively. The yield obtained by supercritical fluid extraction (SFE) was a little lower than that obtained by sonication extraction (SE). The crude extract obtained by SFE was further isolated and purified by semipreparative chromatography with the mobile phase composed of methanol-water (90:1, v/v). Emodin and physcion were obtained with purity 98.6 and 99.1%, respectively, when determined by HPLC, and identification was performed by retention time and UV spectra of the standards. The result suggested that SFE is an alternative and promising method for extraction of the two compounds from P. cuspidatum owing to its environment-friendly properties and fewer coextracts.     

Fuzzy HX环

引入Fuzzy HX环、正则Fuzzy HX环和一致Fuzzy HX环概念,讨论了它们结构和性质及其有关同态与同构关系。     

High-throughput generation of uniform droplets from parallel microchannel droplet generators and the preparation of polystyrene microsphere material

To prepare uniform polystyrene particles with ten microns of diameter, a parallel scaling-up strategy for the capillary-assembled stepwise microchannel was developed, which created uniform droplets with high-throughput and formed a large amount of emulsion templates for the polymerization of styrene and cross-linker. The microchannel droplet generator was robust for the flow rate deviation of the continuous phase in the jetting flow, and droplet generation frequency up to 2.8 × 10⁴ Hz was achieved with only four parallel droplet generators, which were much more efficient than the parallelly scaled microfluidic devices working in dripping flow. 32–52 μm average diameter droplets with 4.5%–8.4% diameter variation coefficients were successfully prepared from the microchannel device fabricated by low-cost 3D-print method, and the droplets were subsequently turned to solid particles via a two-step polymerization in the platform. The polystyrene particles were further reduced to 16.9–23.5 μm with 5.0%–8.6% diameter variation coefficients due to the accompanying emulsion polymerization, and the working capacity of the platform reached hundred milligrams of particles per hour.