Many arthropods have compound eyes, which are made up of numerous separate visual units (microlenses) or ommatidia. These natural compound eyes have exceptional optical properties such as wide field of view (FOV), low aberration, and fast motion tracking capability. In this paper, a large-scale artificial compound eye (ACE) is fabricated efficiently using a combination of inkjet printing and air-assisted deformation processes. Both size and geometry of the microlens are controlled via superposed drops on the substrate. The simulation results show that the light intensity of the ACE follows a systematic distribution for tilted incident light, which represents a significant improvement, compared to planar distributed microlenses. We then manufacture ACEs with different heights and diameters, and their FOVs are compared with the theoretically predicted results. The measured FOV was 50°–140°. The acceptance angles for the different ACEs are determined, and their relationship with the ratio of height to radius (H/r) of the microlens is investigated in more detail. Furthermore, the imaging properties of the microlenses with different angles of incidences are studied, which suggest a FOV up to 140° and an acceptance angle of about 50°. The microlens captures images even at an angle of incidence of about 60°. The corresponding distortion in both the x and y directions is also investigated. Our findings provide guidelines for the development and fabrication of ACEs with large FOVs and acceptance angles, which may find applications in military, robotics, medical imaging, and astronomy.

In recent years, manufacturing servitisation has become a growing characteristic of global firms. Firms develop their service factors, to realise more values and increase their international competitiveness. China, as an important manufacturing centre of the world, has abundant manufacturers seeking for getting more involved in the international market. This paper makes use of detailed customs data and firm‐level data from China, to find how the servitisation in China affects the export durations of Chinese manufacturers. The results demonstrate that manufacturing servitisation input in China contributes to export performance. The service factors have become the important production factors in Chinese manufacturing enterprises. However, China is still at the primary stage of manufacturing servitisation, and Chinese manufacturing enterprises should pay more attention to the whole value chain and seek the transformation from a pure manufacturing enterprise to a service manufacturing enterprise.

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Perovskite solar cells (PSCs) are promising low-cost photovoltaic technologies with high power conversion efficiency (PCE). The crystalline quality of perovskite materials is crucial to the photovoltaic performance of the PSCs. Herein, a simple approach is introduced to prepare high-quality CHNHPbI perovskite films with larger crystalline grains and longer carriers lifetime by using magnetic field to control the nucleation and crystal growth. The fabricated planar CHNHPbI solar cells have an average PCE of 17.84% and the highest PCE of 18.56% using an optimized magnetic field at 80 mT. In contrast, the PSCs fabricated without the magnetic field give an average PCE of 15.52% and the highest PCE of 16.72%. The magnetic field action produces an ordered arrangement of the perovskite ions, improving the crystallinity of the perovskite films and resulting in a higher PCE.

This paper considers the problem of many-to-many disjoint paths in the hypercube Q n with f faulty vertices and obtains the following result. For any integer k with 1 ≤ k ≤ n − 2, any two sets S and T of k fault-free vertices in different parts of Q n (n ≥ 3), if f ≤ 2n − 2k − 3 and each fault-free vertex has at least two fault-free neighbors, then there exist k fully disjoint fault-free paths linking S and T which contain at least 2 n − 2f vertices. This result improves some known results in a sense.

Green crowdfunding is developing as a novel and popular transaction method, which can largely improve the efficiency of raising initial funds and selling innovative green products or services. In this paper, we explore the creator's joint decisions regarding green crowdfunding products of different quality levels that can sufficiently satisfy consumer preferences. Firstly, considering the characteristics of a green crowdfunding product, we present four pricing strategies when substitutes exist. Then we propose the optimal pricing strategies to maximize the total profit for the creator under different circumstances, facing strategic and myopic consumers. Finally, for the heterogeneity of consumer valuations, we compare the total profits of the four pricing strategies under different values of the substitution coefficient to obtain the optimal pricing and product strategies under the coexistence of strategic and myopic consumers. According to the result, we find that when the fraction of high-type consumers and the gap between high and low valuations is big, or when they are both small, traditional single pricing shows its benefit. However, when the green crowdfunding products are better than their substitute, a line of green products is more likely to be optimal.

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