The energy transition is thoroughly conducted worldwide, with a significant shift from fossil fuels to renewable sources. The most essential benefit of utilizing clean energy is environmental sustainability, which reduces greenhouse gas emissions. The technology of multilevel converters is of great significance for converting high-voltage and large-capacity electric energy and improving power consumption efficiency. Compared with traditional topology, modular multilevel converter (MMC) adopts a modular design, and each module is composed of independent sub-modules, which is highly flexible and scalable. This design allows the number of sub-modules to be increased or reduced according to actual needs, adapting to different voltages and power levels. However, its distinct characteristics, such as submodules, circulating currents, and parameter sensitivity, require a sophisticated control system to manage the external and internal variables with high dynamical performance. This paper analyzes the basic principle and topology of the modular multilevel converter; the existing research protocols are reviewed and summarized for these three challenges, respectively. Finally, prospect the future development trends and technical challenges.

Henan province is a key agricultural region in China, influenced strongly by sudden drought. There are relatively few methods to help farmers to make drought projections for the future. The paper tried to use previous monthly SPEI data of time series from 12 stations in Henan from 1978 to 2018 to achieve this purpose. The paper applied Seasonal ARIMA (Autoregressive Integrated Moving Average) to capture patterns of time series and forecast future 5-years value from 2019 to 2024. The terms of models including autoregressive (p), integrated (d), moving average (q) were found based on different tests in order to construct models by removing trends and seasonality of datasets. The final results are ARIMA models of 12 stations in Henan as well as future 5-years predictions of each station. Models effectively capture the main trends and patterns of time-series data; however, some complex patterns and hidden laws still exist in datasets, influencing the accuracy of forecasting. The paper proves Seasonal ARIMA and studying information from past data of SPEI can be useful for preparing drought in Henan. However, the progress in improving the accuracy of forecasting needs to be continued in the future.

As the global population grows, people's demand for residential land has gradually increased. A large number of people have poured into cities, resulting in an increase in various needs for resources, making the original traditional city design extremely burdened. To address this, engineers introduced the concept of smart cities, leveraging technological advancements to enhance urban sustainability and livability. This paper explores the integration of green building technologies into smart city development, aiming to optimize resource use and reduce environmental impact. The research methodology involves literature review and drawing inspiration from various scientific inventions, promoting the use of green technology in the construction of smart cities. This paper finds that green building technologies play a big role in the construction of smart cities.

From the late 19th and the early 20th, people have focused a lot on the application of radio waves ranging from 3 kHz to 300 GHz. Different frequency bands are distributed to various applications. However, the limited range of radio frequency (RF) caused the insufficiency of communication resources across various areas of daily life, including military, medical, and other sectors. Engineers have developed numerous methods for managing and efficiently utilizing radio frequencies. Using Visible light Communication (VLC) is a solution to the RF crisis. This passage mainly researches the improvements that Quantum Dot LED(QLED) can do to increase the capability and stability of VLC compared to traditional LEDs. The purpose of this research is to leverage the advantages of QLED over traditional LEDs to address issues encountered in conventional VLC, such as signal quality degradation due to interference between signals and reduced transmission efficiency caused by indoor obstacles. Through a literature review, this paper finds that the various advantages of QLED make it perfectly suited for VLC and enhance its transmission capability.

Cadmium (Cd), as a widespread heavy metal pollutant in soil, has become one of the globally recognized contaminants due to its high toxicity and bioaccumulative properties. Soil cadmium pollution not only hinders the normal growth of plants but also poses a threat to human health through the food chain. Microbe-plant combined remediation is an essential approach for the treatment of heavy metal contamination in soil. Plants primarily respond to cadmium stress through intrinsic physiological and biochemical adjustments, including inhibiting cadmium absorption, promoting cadmium compartmentalization in vacuoles, and facilitating cadmium efflux from cells. Moreover, plants enhance their tolerance to cadmium through mechanisms such as the regulation of plant hormones. Gene expression regulation is the molecular mechanism underlying plant cadmium tolerance. To date, multiple resistance genes, transcription factors, and microRNAs involved in cadmium tolerance have been identified. Exogenous additives mitigate the effects of cadmium stress on plants by chemical adsorption, enhancing plant cadmium tolerance, and improving the physical and chemical properties of the soil, as well as the structure of soil microbial communities. Investigating the mechanisms by which plants respond to cadmium stress and exploring remediation measures for cadmium pollution will provide a basis for developing effective pollution control and remediation strategies.

With the accelerated advancement of science and technology, the traditional textiles material has been unable to meet the specific functional and performance requirements. Meanwhile, the special structure of aerogel exhibits the drawback of limited thermal stability. The high surface energy of the particles makes it susceptible in high-temperature environments, which can lead to a reduction in specific surface area and even collapse of the porous structure. Aerogel assembled from ceramic nanofibers could be a solution. When the fiber size is reduced from micron to nanometer, the special properties brought by the small size effect and the high specific surface area effect will give the nanofibers new properties such as in light, electricity and sound. This paper provides a comprehensive general introduction of the structure, capability, preparation, and modification techniques employed in ceramic nanofiber aerogel research. The sol-gel electrospinning method can produce nanofiber aerogel with excellent properties. The paper reveals the excellent thermal insulation properties of ceramic grains that is located on ceramic fibers such as ZrO2, SiO2 and Al2O3, combined with the porous structure of aerogel can lock gas molecules, so that they can be used in high temperature environments.

With the continuous development of modern cities, traffic jams have become a growing problem. This paper analyzes and discusses the Intelligent Traffic System (ITS) produced by solving traffic jams. The purpose of this paper is to study the composition algorithms of Intelligent Traffic System, including path planning algorithm, network routing algorithm, and speed guidance algorithm. These three different algorithms make up the Intelligent Traffic System. In this paper, the above three algorithms are introduced and analyzed, and some typical algorithms are selected for analysis and introduction. The challenges encountered in the practical application of Intelligent Traffic System are analyzed, including the limitations of technology, management and policy. The future application trend of Intelligent Traffic System in urban construction is forecasted. Finally, through the integration and application of Intelligent Traffic Systems, the efficiency and quality of urban construction and development can be significantly improved to support the realization of safer and environmentally sustainable Traffic systems.

The existing urban traffic signal control system exhibits certain inefficiencies, including prolonged waiting times and frequent traffic congestion. Research indicates that the integration of neural networks can enhance the effectiveness of intelligent traffic control systems, potentially improving overall traffic flow and reducing delays. Neural network is a highly parallel, nonlinear and highly redundant system. Meanwhile, the self-learning and self-organizing capabilities of neural network have unique advantages for those systems that cannot establish accurate mathematical models. According to the characteristics of complex, variable and random traffic conditions at urban intersections, this paper analyzes the traffic signal control by using neural network control method. This paper introduces a design method of intelligent traffic light based on dynamic time adjustment of traffic flow. By detecting the traffic flow on site, and then allocating the green time of each lane according to the neural network algorithm, the traffic flow dynamic adjustment can be realized, and the traffic capacity of the intersection can be effectively improved. This kind of intelligent control traffic lights can effectively control traffic, and has obvious effects on dreading traffic flow, improving road capacity and reducing traffic accidents.

The design idea of the seven-segment digital tube electronic clock and its potential applications against a contemporary backdrop are the main topics of this study. The seven-segment digital clock's low cost and straightforward design make it popular, especially for gadgets with tight budgets. Accurate time reading, adjustment, countdown, and warning functions are achieved through the study and design of a range of digital circuits, demonstrating the broad application potential of digital logic in time control. The circuit's synchronization, stability, and operability are checked using the Multisim simulation tool, guaranteeing the design's dependability in real-world applications. The findings of the study demonstrate the seven-segment digital clock's long-term utility in particular situations, particularly in settings where affordability and durability are crucial. However, the seven-segment digital clock is also under pressure from competitors due to the growing popularity of new display technologies like OLED and smart technology. According to the research, it can continue to be used in particular industries in the future by merging intelligent characteristics to broaden its range of applications.

In recent years, the global energy market is undergoing an unprecedented transition from traditional fossil fuels to clean energy. At present, China is actively promoting the optimization and upgrading of its energy structure, people will vigorously develop renewable energy sources such as wind power and solar energy. With the increasing number of new energy vehicles, the charging demand of a large number of electric vehicles has become an important issue in the construction of new power systems. In addition, as the global power grid becomes smarter, energy management becomes more diverse and interactive, with users becoming both consumers and providers of energy, the industry and academia are jointly promoting the green, efficient and intelligent development of the global energy system. In this paper, the vehicle-to-grid (V2G) function of domestic charging pile is realized by vehicle-borne bi-directional converters for V2G applications and the feasibility of this goal is analyzed, finally, the prospect and summary are put forward.