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At present, the amount of information on power grid operation and maintenance monitoring image data is increasing, and the requirements for data compression are higher and higher. Based on the improved SPIHT image compression algorithm, this study presents the research of power grid data compression. First, the basic theory of image compression, and the principle of one-dimensional wavelet transform and two-dimensional wavelet transform are introduced. The development process, characteristics, and advantages of image coding are discussed. Then, the shortcomings of the SPIHT algorithm are analyzed, and the SPIHT coding is improved by parallel computation. The parallel wavelet transform algorithm based on the block idea and the parallel SPIHT coding algorithm based on the code tree are proposed in the data parallelism of the compression algorithm. At the same time, the data dependence between tasks in the process of SPIHT image compression coding is analyzed, and the task parallelism in the compression algorithm is realized by using the relative independence of tasks in different threshold coding. Finally, the application and simulation analysis of power grid data based on the SPIHT compression algorithm, the construction of power grid data model simulation, and the composition of two-dimensional power grid data images are carried out. Secondly, the obtained 2D power grid data image is compressed by the SPIHT algorithm and improved SPIHT algorithm, respectively, and the compression effect of the two algorithms on the power grid data image is compared. When the bit rate is 0.5, the compression effect of the improved SPIHT algorithm is 13.6506. When the bit rate is 1, the compression effect of the improved SPIHT algorithm is 18.9287. The results show that the improved SPIHT algorithm can compress the grid data to obtain better grid image quality.

Graphene and transition metal dichalcogenides have been intensively investigated in recent years. Germanium selenide (GeSe) has emerged lately as a new low-symmetry two-dimensional material due to its extraordinary in-plane anisotropic electrical, optical, and optoelectronic properties. However, the controlled synthesis of large-scale GeSe flakes is still a significant challenge because of its strong interlayer coupling and low lattice symmetry. In this work, we have achieved the synthesis of rectangular GeSe microflakes (MFs) with lateral sizes up to 0.33 mm on the glass substrate via a vapor phase deposition technique. The lateral size, thickness, and growth mode of GeSe MFs can be effectively tuned based on space-confined and substrate engineering strategies. Germanium (Ge) MFs with triangular and hexagonal morphologies were simultaneously fabricated in the high-temperature zone. Our experimental results demonstrated that the growth temperature plays an important role in the selective growth of GeSe and Ge MFs. A corresponding growth mechanism has been discussed in detail based on systematic characterizations. Our work provides a new route for the controlled growth of large-size GeSe and Ge MFs, which promotes a promising future in the fields of novel optoelectronic devices. [ABSTRACT FROM AUTHOR]

Atomically thin molybdenum ditelluride (MoTe2) has been intensively studied as an emerging material for electronics and optoelectronics due to its unique properties. While the small free energy difference between the 2H and 1T′ phases of MoTe2 always results in mixed-phase growth, precisely controlled phase transition of MoTe2 nanostructures is still a considerable challenge. Here, the centimeter-scale 1T′, 2H ultrathin MoTe2 films, and in-plane 1T′–2H homojunction have been synthesized by ambient pressure chemical vapor deposition based on the precursor design and space-confined strategies. The controllable growth of pure 1T′, 2H MoTe2, and 1T′–2H mixed-phase MoTe2 with phase separation and homogeneous mixture, respectively, has been achieved by adjusting growth temperature and growth time. The thickness of synthesized 1T′ and 2H ultrathin MoTe2 films can be effectively controlled by tuning the space-confined height. The corresponding growth mechanism was further illuminated based on systematically experimental characterizations and computational fluid dynamics simulations. The electrical transport properties of 1T′ and 2H MoTe2 films were investigated by conductive atomic force microscope and MoTe2-based thin-film field-effect transistors. Our experimental results provide a new route to realize the phase transition of two-dimensional materials, which makes these materials easily accessible as functional building blocks for next-generation electronic and optoelectronic devices. [ABSTRACT FROM AUTHOR]