Particle mass and particulate size are two important parameters used to characterize the aerosol. Currently, there are a few methods for measuring particle mass concentration and particle size. However, the existing methods have their own shortcomings. In this article, we describe a novel laser scattering instrument that measures mass concentration and particle size in real time over a wide concentration range. This instrument combines laser scattering and time-of-flight aerodynamics in one optical device. There are two innovations in this paper: (1) Two APD detectors are used to receive scattered light. One receives forward-scattered light and the other receives side-scattered light. The advantage is that the sensitivity of the detector is increased greatly, and the ratio of forward and side scattering is used to further obtain the size and shape information of the particles. (2) In order to measure the high concentrations of aerosol, a high-speed ADC and FPGA is combined to achieve an anti-overlap algorithm objective. It has been verified by experiments that the anti-overlapping algorithm can effectively improve the applicability of the aerodynamic particle size spectrometer under high concentration conditions.

In order to solve the problem of the continuous online monitoring of the fixed pollution source emission particles, on the basis of the advantages and disadvantages of the comprehensive analysis of the extinction method, the β-ray absorption method, the micro-oscillating balance method, the charge transfer method, and the light scattering method, the particle size distribution and concentration optical detection system based on aerodynamic particle size spectrometer is designed according to the Mie light scattering principle. A high-performance aerodynamic particle size spectrometer is designed using a single-wavelength method to measure the concentration of particulate matter, and the equipment and the detection system are used in the continuous monitoring of particulate matter emitted by thermal power plants and compared with the ES632 equipment. Through the system test, the results show that compared with the ES632 equipment performance, the lowest concentration measured by the design of aerodynamic particle size spectrometer equipment can reach 0.1mg/m³ with a measurement accuracy of 0.01mg/m³. Compared with the ES632 equipment, the measurement concentration value is 8 higher, which meets the test requirements.

As a force-based finite element method (FEM), large increment method (LIM) shows unique advantages in material nonlinearity problems. In LIM for material nonlinearity analysis, adaptive load incremental step is a fundamental step for its successful application. In this work, a strategy to automatically refine the load incremental step is proposed in the framework of LIM. The adaptive load incremental step is an iterative process based on the whole loading process, and the location and number of post-refined incremental steps are determined by the posteriori error of energy on the pre-refined incremental steps. Furthermore, the iterative results from the pre-refined incremental steps can be utilized as the initial value to calculate the result for the post-refined incremental steps, which would significantly improve the computational accuracy and efficiency. The strategy is demonstrated using a two-dimensional example with a bilinear hardening material model under cyclic loading, which verifies the accuracy and efficiency of the strategy in LIM. Compared with the displacement-based FEM, which relies upon a step-by-step incremental approach stemming from flow theory, the adaptive load incremental step based on the whole loading process of LIM can avoid the cumulative errors caused by step-by-step in global stage and can quantify the accuracy of results. This work provides a guidance for the practical application of LIM in nonlinear problems.