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The development of micro-fabrication and micro-assembly technology is indispensable for the future manufacturing of miniaturized, functional, and integrated devices. This paper proposes a planar micro-assembly technology to make the assembly of micro-objects easier. Firstly, delicate three-dimensional (3D) structures were fabricated on glass and silicon slice substrates using femtosecond laser two-photon polymerization (2PP). Secondly, transparent fluorescent scintillation ceramic powder, referred to as fluorescent powder, was assembled using a laboratory-made 3D moving heating micro-operator into a microstructure on a glass substrate, and this device is used to assemble the graphene powder into the microstructure on the silicon slice substrate. The fluorescence spectra and Raman spectra characterizations of the fluorescent powder and graphene powder in the microstructure were carried out by using excitation light at 405 nm and 532 nm, respectively. According to the above results, it can be concluded that the powder properties of the fluorescent powder and graphene powder assembled into the microstructure were not changed. The experimental device could not only assemble many micron-sized powder materials into hollow microstructures of arbitrary shape but also joined microstructures with different materials and characteristics to form a complex hybrid microstructure system.

Water injection is one of the most economical and effective methods of ensuring the continuous and stable production of an oil field and improving oil recovery. However, scale formation is unavoidable in long-term water injection, and this seriously affects and restricts oil field development. Our research on scale formation in injection–production units was based on the dissolution–precipitation equilibrium, thermodynamics, ionic association theory, the solubility product rule, and the common ion effect. Considering formation temperature, pressure, scale ion concentration, and rate of flow as influencing factors, we established a formation pressure field model, a temperature field model, a porosity model, a scale formation model, and a scale inhibition model, which together constitute a numerical model of scale formation in an injection–production unit. We then used MATLAB software to analyze the influence of various factors on the total amount of scale, the scale range, and the scale distribution, as well as the influence of scale formation on the apparent injectivity index and permeability. To verify the reliability of our model, we introduced a scale inhibition rate, and we compared the scale inhibition rate that we calculated with the scale inhibition rate measured by experiment. The simulation shows that scale formation is mainly affected by formation temperature and scale ion concentration distribution, but that formation pressure has relatively little influence on it. Formation pressure decreases gradually along the direction of water flooding in an injection–production unit, and formation temperature changes mainly near the wellbore of the injection well. Along the direction of water flooding, scale formation first increases rapidly and then decreases rapidly. The reason for this trend is that with low formation temperature near the injection well, a small dissolution equilibrium constant and a high flow rate make scale formation difficult. Radially outward, the formation temperature increases and the flow rate decreases greatly, making it easier for scale to form. Even further out, the scale ion concentration is lower than the minimum scale concentration and scale can no longer form.

Graphene that is directly integratable into electronic devices after its growth is highly desirable but is difficult to fabricate due to its relatively high growth temperatures (∼1000 °C) and inevitable transfer step. Herein, we propose a convenient and feasible strategy to directly synthesize high-quality polycrystalline graphene on Si substrates by utilizing plasma-assisted chemical vapor deposition (PACVD), where three main features inevitable to traditional growth methods, i.e., transition metals as catalysts, post-transfer process and high growth temperature, can be thoroughly circumvented. Notably, the growth temperature is significantly reduced and reaches as low as 700 °C. The utilized PACVD provides exceptional abilities of hydrocarbon pyrolysis and graphene formation even on unusual Si substrates. Furthermore, the as-grown graphene-on-Si (GOS) exhibits superior capabilities that can be used to directly fabricate high performance optoelectronic devices, e.g., photodetectors. Typical current rectification characteristics and good photovoltaic conversion efficiency are demonstrated in as-grown graphene/Si Schottky junctions.

In this paper, we introduce some basic idea of Variational iteration method for short (VIM) to solve the Volterra’s integro-differential equations. The VIM is used to solve effectively, easily, and accurately a large class of non-linear problems with approximations which converge rapidly to accurate solutions. For linear problems, it’s exact solution can be obtained by only one iteration step due to the fact that the Lagrange multiplier can be exactly identified. It is to be noted that the Lagrange multiplier reduces the iteration on integral operator and also minimizes the computational time. The method requires no transformation or linearization of any forms. Two numerical examples are presented to show the effectiveness and efficiency of the method. Also, we compare the result with the result from Homotopy perturbation method (HPM). Finally, we investigate the absolute difference between variational iteration method and homotopy perturbation method and draw the graph of difference function by using Mathematica.

Based on the optical rotatory dispersion and zero reflection of the p-polarization light at the Brewster angle, a novel optical filter that employs only one NaBrO3 crystal and one polarizer are proposed and demonstrated. Performance of the optical filter is studied both theoretically and experimentally. Results show that the green light is becomes nearly extinct when the angles of the polarizer are set at 80° and 260°, whereas the red light becomes nearly extinct when the angles of the polarizer are set at 116° and 296°. Isolation of more than 8 dB can be achieved. The measured extinction ratios are 12.3 and 12.6 dB for green and red lights, respectively.