The promotion and inhibition of chromium and kinetic analysis on the growth of Platymonas Helgolandica

In this work, Platymonas helgolandica was used as an experimental material to study the effect of chromium on it. Under the experimental ecological condition, the concentrations of Cr (VI) were set as 0, 0.05, 0.1, 1, and 10 mg/L. Every concentration designed with three parallel groups. The ecotoxicology method was used to investigate the impact of Cr (VI) on P. helgolandica, and (EC50) was calculated by the method of linear interpolation. The results showed the growth of P. helgolandica had a more obvious “Hormesis” when chromium was 0.05 mg/L. However, with Cr (VI) increased, the inhibition on P. helgolandica was increasing, and the cell density of P. helgolandica decreased. The EC50 achieved at 24 h, 48 h, and 72 h revealed that the relative growth rate had a downward trend over time. The remodified Logistic model, the modified Gompertz model, and the Logistic model were suitable to describe cell density in an operating cycle and were beneficial to explore the growth of P. helgolandica

Application of air disc brake in mining electric locomotive

In order to shorten the braking distance of mining electric locomotive and improve the safety of underground transportation effectively. The existing handwheel-brake shoe brake device is analyzed. In view of its shortcomings, an air disc brake device and a tread sweeper are put forward. Through calculation verification and simulation analysis, it is found that the device can shorten the braking distance of mining electric locomotive effectively and it can meet the requirements of The Specification of Narrow Tramroad Gauge Electric Locomotive for Mine. It has a certain degree of application value and practical significance

Asymmetric quantum well broadband thyristor laser

A broadband thyristor laser based on InGaAs/GaAs asymmetric quantum well (AQW) is fabricated by metal organic chemical vapor deposition (MOCVD). The 3-μm-wide Fabry–Perot (FP) ridge-waveguide laser shows an S-shape I−V characteristic and exhibits a flat-topped broadband optical spectrum coverage of ~27 nm (Δ−10 dB) at a center wavelength of ~1090 nm with a total output power of 137 mW under pulsed operation. The AQW structure was carefully designed to establish multiple energy states within, in order to broaden the gain spectrum. An obvious blue shift emission, which is not generally acquired in QW laser diodes, is observed in the broadening process of the optical spectrum as the injection current increases. This blue shift spectrum broadening is considered to result from the prominent band-filling effect enhanced by the multiple energy states of the AQW structure, as well as the optical feedback effect contributed by the thyristor laser structure

Review and Prospect on Development of Urban Flood Warning System

An overall research and analysis on past development track was of great significance for the further development of new theories, models, technologies and applications of urban flood warning system. Thus, the paper comprehensively discussed the development track of urban flood warning system, especially its structures and supporting technologies. From the analysis, it could be seen clearly that demands and technologies were two major driving forces for the development of urban flood warning system in the era of big data. Moreover, it was illustrated that new demands and problems had to be faced, and discussed how to meet them in the future by integrating technologies of big data and cloud computing

Application of Acetate as a Substrate for the Production of Value-Added Chemicals in <em>Escherichia coli</em>

At present, the production of the majority of valuable chemicals is dependent on the microbial fermentation of carbohydrate substrates. However, direct competition is a potential problem for microbial feedstocks that are also used within the food/feed industries. The use of alternative carbon sources, such as acetate, has therefore become a research focus. As a common organic acid, acetate can be generated from lignocellulosic biomass and C1 gases, as well as being a major byproduct in microbial fermentation, especially in the presence of an excess carbon source. As a model microorganism, Escherichia coli has been widely applied in the production of valuable chemicals using different carbon sources. Recently, several valuable chemicals (e.g., succinic acid, itaconic acid, isobutanol, and mevalonic acid) have been investigated for synthesis in E. coli using acetate as the sole carbon source. In this review, we summarize the acetate metabolic pathway in E. coli and recent research into the microbial production of chemical compounds in E. coli using acetate as the carbon source. Although microbial synthetic pathways for different compounds have been developed in E. coli, the production titer and yield are insufficient for commercial applications. Finally, we discuss the development prospects and challenges of using acetate for microbial fermentation

Fast Hologram Calculation Method Based on Wavefront Precise Diffraction

In this paper, a fast hologram calculation method based on wavefront precise diffraction is proposed. By analyzing the diffraction characteristics of the object point on the 3D object, the effective viewing area of the reproduced image is analyzed. Based on the effective viewing area, the effective hologram size of the object point is obtained, and then the accurate diffraction calculation from the object point to the wavefront recording plane (WRP) is performed. By calculating all the object points on the recorded object, the optimized WRP of the whole 3D object can be obtained. The final hologram is obtained by calculating the diffraction light field from the WRP to the holographic plane. Compared with the traditional method, the proposed method can improve the calculation speed by more than 55%, while the image quality of the holographic 3D display is not affected. The proposed calculation method provides an idea for fast calculation of holograms and is expected to contribute to the development of dynamic holographic displays

A GPU-Based Parallel Procedure for Nonlinear Analysis of Complex Structures Using a Coupled FEM/DEM Approach

This study reports the GPU parallelization of complex three-dimensional software for nonlinear analysis of concrete structures. It focuses on coupled thermomechanical analysis of complex structures. A coupled FEM/DEM approach (CDEM) is given from a fundamental theoretical viewpoint. As the modeling of a large structure by means of FEM/DEM may lead to prohibitive computation times, a parallelization strategy is required. With the substantial development of computer science, a GPU-based parallel procedure is implemented. A comparative study between the GPU and CPU computation results is presented, and the runtimes and speedups are analyzed. The results show that dramatic performance improvements are gained from GPU parallelization