The Random Forest Model for Analyzing and Forecasting the US Stock Market in the Context of Smart Finance

The stock market is a crucial component of the financial market, playing a vital role in wealth accumulation for investors, financing costs for listed companies, and the stable development of the national macroeconomy. Significant fluctuations in the stock market can damage the interests of stock investors and cause an imbalance in the industrial structure, which can interfere with the macro level development of the national economy. The prediction of stock price trends is a popular research topic in academia. Predicting the three trends of stock pricesrising, sideways, and falling can assist investors in making informed decisions about buying, holding, or selling stocks. Establishing an effective forecasting model for predicting these trends is of substantial practical importance. This paper evaluates the predictive performance of random forest models combined with artificial intelligence on a test set of four stocks using optimal parameters. The evaluation considers both predictive accuracy and time efficiency.Comment: 10 pages, 8 figure

AI-Driven Anonymization: Protecting Personal Data Privacy While Leveraging Machine Learning

The development of artificial intelligence has significantly transformed people's lives. However, it has also posed a significant threat to privacy and security, with numerous instances of personal information being exposed online and reports of criminal attacks and theft. Consequently, the need to achieve intelligent protection of personal information through machine learning algorithms has become a paramount concern. Artificial intelligence leverages advanced algorithms and technologies to effectively encrypt and anonymize personal data, enabling valuable data analysis and utilization while safeguarding privacy. This paper focuses on personal data privacy protection and the promotion of anonymity as its core research objectives. It achieves personal data privacy protection and detection through the use of machine learning's differential privacy protection algorithm. The paper also addresses existing challenges in machine learning related to privacy and personal data protection, offers improvement suggestions, and analyzes factors impacting datasets to enable timely personal data privacy detection and protection.Comment: 9 pages, 6 figure

Effects of Tillage Methods on Crop Root Growth Trend Based on 3D Modeling Technology

Strip rotary tillage seeding technology has been widely used in rice–wheat rotation system, benefiting the economy greatly. The purpose of farming is to create a comfortable seedbed environment for crop growth. Therefore, it is necessary to consider the effects of tillage methods on wheat root configuration and growth trend in the research of strip tillage, instead of just focusing on optimizing the shape of tillage tools, sowing methods, and soil fragmentation. To clarify the effects of different tillage methods on crop root growth trends, a two-year wheat planting experiment was carried out. Strip tillage (ST1 and ST2) and full width tillage treatment (FT) were designed, 3D models of root structure and soil on the surface of the seedbed wall were established, and four quantitative indexes were proposed: soil surface roughness of seedbed wall (SR), difference coefficient of root soil space occupation (P), difference coefficient of root angle expansion trend (PA), and difference coefficient of root length expansion trend (PL). The results showed that the cultivation method directly affects the growth trend of wheat roots. The wheat roots tended to grow along the inter-specific direction under ST treatment on the 14th day, and the average P, PA, and PL were as high as 38, 43, and 55, respectively. The SR produced by ST1 treatment was 70% lower than that of ST2 treatment, suggesting ST1 treatment had more serious restrictions on root growth. P, PA, and PL in ST1 treatment were 38.5%, 14%, and 43% higher than those in ST2 treatment within 14 days, respectively. This paper briefly explains the effects of tillage methods on the growth trend of wheat roots, provides new methods and technologies for the rapid and effective acquisition of soil surface information, solved the problem of the trend of root expansion being difficult to quantify, and provided a new direction for the optimization of tillage methods

Combination of utilization of CO2 from flue gas of biomass power plant and medium recycling to enhance cost-effective Spirulina production

Carbon dioxide (CO2) sequestration by microalgae has received widespread attention. Growth and biomass quality using flue gas, combined with medium recycling, were evaluated in this study. Results indicated that Spirulina maxima FACHB 438 can use flue gas from biomass power plant as sole carbon source. The final biomass of 26.30, 22.10, and 23.95 g in fresh medium (FM), recycled medium (RM), and recycled medium with activated carbon treatment (RM + AC) was harvested in flat-plate photobioreactors with 10 L working volume after 5 cycles, respectively. The mean specific growth rate and CO2 fixation rate did not differ significantly (p &lt; 0.05), illustrating good growth performance in the three treatments. Activated carbon enhanced growth in RM + AC by 8.4% compared with RM. The quality of biomass in either FM or RM satisfies the Chinese standard for food/feed additives. This manner of mass culture reduced the cost of nutrients by up to 42%. Therefore, combination of CO2 sequestration from biomass power plant and medium recycling is demonstrated to be a new way to enhance the cost-effective Spirulina production.</p

Grain boundary re-crystallization and sub-nano regions leading to high plateau figure of merit for Bi2Te3 nanoflakes

Nanoengineering is an effective strategy to strengthen phonon scattering, reduce lattice thermal conductivity and boost thermoelectric material performance. However, nanostructure features are generally in the size of ∼10 nm, and the fine control of nanostructure characteristics down to the sub-nano level (below several nanometers) remains as a key challenge. Here, we demonstrate that solvothermally synthesized Bi2Te3 can re-crystallize preferentially at the grain boundaries to form sub-nano boundary regions with width 1.2 (from ∼323 to ∼423 K) and a high average zT of ∼1.18 (from 303 to 473 K) have been achieved in the Bi2Te3 pellet sintered at 593 K. This study not only reveals the formation mechanism of sub-nano boundary regions but also demonstrates that these sub-nano boundary regions and their formation process can effectively induce synergistic effects contributing to high thermoelectric performance, and guide the design of high-performance thermoelectric materials.</p

Tuning the Saturated Vapor Pressure of Solvothermal Synthesis to Boost the Thermoelectric Performance of Pristine Bi2Te3 Polycrystals by Anisotropy Strengthening

Bi2Te3 is one of the most promising thermoelectric materials that target near-room-temperature applications due to its high thermoelectric potential at these temperatures. In this work, we report a new route to significantly improve the thermoelectric performance of pristine Bi2Te3 polycrystals. We design the mixed solutions composed of H2O and ethylene glycol (EG) as novel solvents to solvothermally synthesize Bi2Te3 crystalline microplates. It is found that the addition of H2O can boost the saturated vapor pressure of the mixed solutions during the solvothermal synthesis and significantly drive the crystal growth of Bi2Te3 microplates along their in-plane directions due to the tuning of kinetic conditions. Such a unique route strengthens the anisotropy of the bulk materials sintered from these microplates, leading to improved carrier mobility of >170 cm2 V-1 s-1 and in turn a high electrical conductivity of >1400 S cm-1 at room temperature. Combined with a high absolute Seebeck coefficient of >140 μV K-1, a competitively high power factor of ∼30 μW cm-1 K-2 can be achieved in the solvothermally synthesized samples. Besides, compared with the bulk material sintered from commercial Bi2Te3 powders with a figure of merit of 0.2 at 369 K, the figure of merit of the bulk material developed in this work is significantly improved by ∼167% (0.56), indicating great potential for practical applications.</p

Approaching high thermoelectric performance in p-type Cu3SbS4-based materials by rational electronic and nano/microstructural engineering

Due to the eco-friendly and earth-abundant features, p-type Cu3SbS4-based sulfides have shown great potential as cost-effective thermoelectric materials for practical applications in power generation and refrigeration. However, low electrical conductivities of p-type Cu3SbS4-based sulfides result in insufficient thermoelectric properties. In this work, a high average ZT of 0.45 and a maximum ZT of 0.85 at 623 K were obtained in Cu3SbS4-based sulfides through rational electronic and nano/microstructural engineering, achieved by mechanical alloying combined with fast spark plasma sintering techniques. Guided by theoretical calculations, we first study the physical properties of Cu3SbS4-xSex to explore the best composition (Cu3SbS3Se) that balances high thermoelectric performance, high thermal stability, and high mechanical performance. Based on this composition, we employed 4 % p-type AgSnSe2 with a narrow bandgap of ∼0.15 eV to further boost the electrical conductivity of Cu3SbS3Se, generating a high power factor of 12.65 μW cm−1 K−2 at 623 K. In addition, comprehensive nano/microstructural characterizations indicate that a combination of dense grain boundaries, phase boundaries, and multi-dimensional lattice defects acts as rich sources to intensely scatter multi-frequency phonons, leading to a decreased thermal conductivity of 0.93 W m−1 K−1 at 623 K. This work provides a new route to boost the thermoelectric properties of sulfides for practical applications.</p

Solvothermally silver doping boosting the thermoelectric performance of polycrystalline Bi2Te3

Bismuth telluride (Bi2Te3) is one of the most promising thermoelectric materials for commercial application at room temperature, but the thermoelectric performance of these materials still needs to be improved. In this study, we report a type of solvothermally Ag-doped Bi2Te3 microplate. By sintering these microplates into polycrystalline bulk materials, a high room-temperature figure of merit of 1 has been achieved. Based on comprehensive micro/nanostructural characterizations, we found that the solvothermally doped Ag in Bi2Te3 plays two main roles, namely as the dopants that effectively induce the point defects of AgBi and forming Ag2Te nanophases. AgBi can provide additional hole charge carriers, effectively adjusting the initially high electron carrier concentration in the system, while the Ag2Te nanophases effectively trigger energy filtering effect to maintain a high Seebeck coefficient, thereby contributing to a competitively high power factor of 25.5 μW cm−1 K−2 at 298 K. Simultaneously, a low thermal conductivity of 0.74 W m−1 K−1 is obtained due to the strong phonon scattering at various lattice imperfections, induced by the solvothermally Ag-doping, which include point defects, grain/phase boundaries, local lattice distortions, and dislocations. This work fills the gap in knowledge on the solvothermally Ag-doping mechanism in Bi2Te3 and provides guidance for the innovative design of high-performing inorganic thermoelectrics.</p

Dative Epitaxy of Commensurate Monocrystalline Covalent van der Waals Moiré Supercrystal

Realizing van der Waals (vdW) epitaxy in the 1980s represents a breakthrough that circumvents the stringent lattice matching and processing compatibility requirements in conventional covalent heteroepitaxy. However, due to the weak vdW interactions, there is little control over film qualities by the substrate. Typically, discrete domains with a spread of misorientation angles are formed, limiting the applicability of vdW epitaxy. Here, the epitaxial growth of monocrystalline, covalent Cr5Te8 2D crystals on monolayer vdW WSe2 by chemical vapor deposition is reported, driven by interfacial dative bond formation. The lattice of Cr5Te8, with a lateral dimension of a few tens of micrometers, is fully commensurate with that of WSe2 via 3 × 3 (Cr5Te8)/7 × 7 (WSe2) supercell matching, forming a single-crystalline moiré superlattice. This work establishes a conceptually distinct paradigm of thin-film epitaxy, termed “dative epitaxy”, which takes full advantage of covalent epitaxy with chemical bonding for fixing the atomic registry and crystal orientation, while circumventing its stringent lattice matching and processing compatibility requirements; conversely, it ensures the full flexibility of vdW epitaxy, while avoiding its poor orientation control. Cr5Te8 2D crystals grown by dative epitaxy exhibit square magnetic hysteresis, suggesting minimized interfacial defects that can serve as pinning sites