Based on the spread of the new crown epidemic, the use of masks has been popularized, so it has a significant impact on the development of face recognition under the cover. The study of how to improve the performance of face recognition under occlusion conditions is also an important topic in the field of face recognition in the future. At the same time, the neural network model is one of the most important models in deep learning, in the field of image classification, face recognition based on deep network has also been proved to be an efficient feature extraction method, this paper divides the face recognition method based on occlusion into two categories: local feature class based on non-occlusion area and feature class based on recognition occlusion area; The basic processes of these two types of methods are summarized, and the specific cases of these two types of occlusion face recognition methods are analyzed. Further summarize the advantages and disadvantages of each and elaborate them. At the end of the article, the shortcomings and future development trends of the current shielding face recognition research are summarized.

Out of consideration for sustainable development, photovoltaic power generation system has become a hot research issue in the future energy strategy due to its significant cleanliness and reproducibility. Meanwhile, playing an important role in connecting the PV cell and the grid, the non-isolated photovoltaic inverter not only has the ability to convert energy with great efficiency but also with low loss and cost. In that case, the non-isolated inverter is widely used in the production. However, the leakage current is a big challenge that should be addressed with caution. This paper focuses on the leakage current mitigation strategy and makes a comprehensive analysis of each topology. The author analyses the generation mechanism of leakage current based on the single-phase inverter circuit. After that, the common ground type inverter topology and the H-Bridge type inverter topology will be further analysed for their universal utilization. Specific topologies from the two types of inverters are under comparison based on several perspectives, ranging from the degree of leakage current suppression to the complexity of the circuit structure, from the difficulty of analysis to the economic performance of the inverter. In addition, some improvement measures are proposed.

With the advancement of modern science and technology, wireless communication technology has grown rapidly. A number of common standards for wireless data transmission have emerged, primarily for long-distance and short-range wireless communication. This paper compares several common wireless communication transmission technologies, including satellite communication, Bluetooth, WiFi, NFC, etc. Wireless communication technology has now entered the 5G stage. From the previous SMS to the current video conference, the transmission rate and transmission accuracy have been greatly improved. Wi-Fi facilities everywhere in the city, Bluetooth transmission, mobile phone NFC payment, etc. are convenient and improve people's lives. Wireless communication technology also has many applications, such as 5G technology, Internet of Things technology, and the development of artificial intelligence technology.

Based on the existing literature and data, this paper starts from the principle of radio frequency identification technology, analyses the situation of the application field of RFID and predicts its development prospect. The results show that RFID technology is a kind of technology that uses the transmission characteristics of RF signals through space alternating electromagnetic coupling to identify targets and thus realize rapid automatic identification. Since it was developed and used in warfare in the mid-twentieth century, RF identification technology has developed rapidly and developed a variety of applications. Today, with the development of electronic technology and communication technology, RF identification technology already has a wide and irreplaceable role in medicine, military and food safety. It is not difficult to imagine that with more joint applications of new technology, radio frequency-related algorithm improvement, radio frequency tag price reduction, and other conditions, the technology will have a more extensive and profound application in the future.

This paper discusses the method for artificial potential field in traditional sense. It is based on the algorithm with the planning of physics that guides a robot along a gradient toward a target endpoint by applying forces with gravitation and repulse within a robot environment. The article proposes to improve the potential field method by incorporating the A-star algorithm for the improvement of path planning in accuracy and efficiency. The A-star algorithm uses a cost function to measure the goodness of a node and finds the optimal path totally and thoroughly through heuristic search. The proposed method uses the A-star algorithm to generate the optimal path, which takes potential field and its method as basis, thus repeating the process until the robot reaches the end point. By combining the A-star algorithm and the method based on artificial potential field, the robot's driving route is made more reasonable, and thus testing and verifying how the method works through an experiment with simulation.

In this era of information explosion, the improvement of communication capacity has become an urgent problem, and the improvement of transmission speed and the reduction of channel spacing are near the limit, so widening the available bandwidth of fiber optic transmission is the most feasible method. The research progress of fiber optic amplifiers is analyzed, and the outlook is presented. Researchers are working to find breakthroughs in C++ band, L++ band, and C+L band, starting with amplifier’s materials, structures, and designs. The EDFA targeted C++ and L++ band have been widely studying these years while different types of amplifiers have been invented to simultaneously work on C+L band. Also, as quantum dot is introduced to design innovated fiber amplifier, more new amplifiers need to be invented to achieve better amplification. This paper presents the recent research results of the above-mentioned research directions, and the next goal of researchers is to stabilize all these amplifiers’ gain flatness and production implement ability.

Research on optical fiber amplifiers has gotten much more in-depth in recent years as a direct result of the emergence of the information age. The most effective of these materials are optical fibers that have been doped with rare earth elements. Lasers that have gain media composed of rare-earth doped optical fibers find widespread use in fields such as optical communication, medicine, and the processing of materials. For different rare earth ions, especially for bismuth-doped fiber amplifiers, bismuth-doped fiber has a good prospect in fiber amplifiers and lasers due to its unique luminescence characteristics and ultra-wideband near-infrared luminescence of bismuth. Therefore, for bismuth-doped fiber amplifiers, in this paper, the pump wavelength is designed for the signal wavelength range, energy level structure, and electron transition process. The corresponding rate equation and power equation are established. At the same time, the gain spectrum changes with the fiber length and doping concentration are calculated using Matlab programming, and the maximum and minimum gain differences are minimized using Matlab calculations.

Optical fiber amplifier technology is to incorporate rare earth elements that can produce a laser into the fiber core, and the DC light excitation provided by the laser makes the amplification through the light signal. Neodymium-doped fiber laser was first developed and received much attention early on. Neodymium doped fibers had the highest pumping efficiency around 920 nm, 1060 nm and 1350 nm. The simulated annealing algorithm belongs to a stochastic optimization algorithm, which is mainly used to find the optimal global solution of the objective function. The author considers that this algorithm can be used to find the full capacity of the fiber amplifier, that is, a new method to find the full capacity, to develop new applications of this algorithm. In this paper, the fiber length and doped concentration were optimized to calculate the maximum power of the neodymium-doped fiber amplifier 1250-1350 nm by using the Matlab modeling and simulated annealing algorithm. The gain was most significant at a fiber length of 2.4 m and a doping concentration of 3.2*(10^25). The maximum profit is: 53.2182dB.

In this research, the performance of thulium-doped fiber lasers is analyzed and a mathematical model is established. Thulium-doped fiber amplifiers are the focus of this article. A large number of simulations have been carried out in the MATLAB simulation environment, and the main work and innovation points are as follows: firstly, the energy level structure characteristics of thulium were studied, and its spectral characteristics were analyzed. After consulting some information, 3H4 to 3H6 energy level has been selected in modeling. Secondly, use the rate equations and the power propagation equations to provide a theoretical analysis of the pumping mode of thulium-doped fiber lasers. And a mathematical model of a thulium-doped fiber laser was established. The parameters such as fiber length and doping concentration in the model are discussed. Finally, to find the appropriate parameters, the genetic optimization algorithm is used to optimize the fiber length and doping concentration, and then we can get the parameters corresponding to the maximum output power of the thulium-doped fiber amplifier.

Nowadays, with the development of the space technology and the maturity of traditional launch vehicle technology, there are sufficient foundations for the research of higher-level space vehicles. As space vehicles gradually enter the commercial market, the demand for better cost control and higher carry capacity has been put forward. The recovery and reuse of space vehicles, especially launch vehicle, often means higher resource utilization and effective cost control, which has unprecedented advantages in business mode. Many countries and organizations have shown concern about the reusable vehicles. In order to facilitate the further research of reusable rocket technology, this article summaries the research and developments of reusable vehicles over the years and sorts out the overall scheme and key technologies of it. In particular, in view of the successful case of Falcon 9, this article analyses the commercialization experience of SpaceX reusable rockets and its business model. This article may offer a reference for the reusable rocket technology development.

This article discusses the exciting advancements in technology that are being made in the Braille field, with a focus on 3D printing, sensor technology, and artificial intelligence (AI). These technologies are transforming the way that blind people access and interact with Braille, improving their quality of life and making the world a more inclusive place. The use of 3D printing is an important development in Braille production. Traditional printing methods can result in Braille books and materials that are difficult to read due to errors and inaccuracies. 3D printing, however, allows for more precision and accuracy, resulting in higher quality Braille materials. This technology can also be used to create custom Braille materials to suit individual needs. Sensor technology is another important advancement in the field of Braille. A new type of assistive device, such as a wristband-style smart reader, is being developed. These devices use sensors to detect and translate Braille into spoken or written language, thereby enhancing communication and access to information for blind people. Finally, AI technology is making significant progress in recognizing and translating Braille. With the help of AI tools, blind people can more easily and accurately understand Braille and interact with the world around them. For example, AI-powered reading machines can scan and recognize Braille characters and translate them into spoken or written language, allowing blind people to access a wider range of information with greater ease.

In the era of rapid urbanization, the existing buildings in old communities can no longer meet the living needs of residents, and the community space urgently needs to be updated. The article explores the use of micro updates to create community space and combines participatory creation to analyse the principles of community space creation, including spatial social power, knowledge interaction power, critical thinking power, and local inclusiveness. From the construction mode and process perspective, this paper analyses the renovation case of basement 302 of Wangjing Huajiadi in Beijing. Starting from the needs of residents, problems encountered, and conflicts encountered, and by creating a skill exchange space, a community construction mode of co-creation and symbiosis has been summarized.

Quadcopter UAVs are increasingly used for military and civilian applications such as surveillance, reconnaissance, pesticide spraying, and traffic monitoring due to their simplicity of operation, ease of attitude adjustment, and ability to take off and land vertically. The flight control system is the key to the aircraft's ability to perform flight tasks. However, when faced with external disturbances, obstacles, and uncertain parameters, traditional PID control is unable to meet the demands of complex flight tasks. Research on more advanced control strategies is the trend of future development. This paper surveys the flight control methods of quadrotor UAVs in the past two decades and classifies and introduces these methods one by one. Finally, the experimental feasibility of these methods is discussed, the advantages and disadvantages of these methods are briefly compared, and the future development trend of UAV flight control systems is analyzed. An important reference is provided for the development of quadrotor UAV flight control algorithm research.

As semiconductor production processes continue to advance, CMOS image sensors are becoming increasingly popular and are gradually replacing traditional CCD sensors as the mainstream option in the market. Because CMOS image sensors adopt the standard CMOS semiconductor production process, which provides advantages such as low static power consumption, large noise tolerance, strong anti-interference ability, and fast working speed. This article is going to provide an overview of CMOS image sensors and examine their various applications. To achieve this, this article will provide some background information on CMOS image sensors, including a discussion of their structure, components, and working principles. A comprehensive literature review was conducted to explore the characteristics and benefits of CMOS image sensors in applications such as intelligent surveillance systems (ISS), space, and medical. This paper also discusses recent advances in CMOS image sensor technology, namely backside illumination, global shutter, and 3D imaging, and their impact on various industries. Despite the advantages of CMOS image sensors, they still have some limitations and shortcomings. Therefore, further progress in industrial development is necessary to improve the quality of these products.

This paper focuses on using gas turbines in various industries, particularly aviation, due to their unique power-to-weight ratio. It provides a detailed description of how gas turbines operate based on the thermodynamic Brayton cycle, which includes compressors, combustors, and power turbines. Additionally, the paper analyses both ideal and realistic cycles of gas turbines. Despite numerous advantages, gas turbines have limitations, such as high fuel consumption. However, technological advancements have led to the development of more efficient and quieter gas turbines. The paper explains the classification of jet engines, including turbojets, turboprops, and turbofans, each with specific applications. Moreover, the paper discusses the efforts to reduce the use of fossil fuels in aviation due to the increasing awareness of the impact of climate change. Scientists and engineers are exploring substitute fuels and materials and developing gas turbine systems that maximize work generated with minimal combustion; thus, this paper also highlights the importance of developing more efficient and environmentally friendly gas turbines to reduce the industry's carbon footprint while maintaining their productivity.

This article mainly discusses one of the most important applications of stationary gas turbines—the small-scale power generation. Micro/Small-scale gas turbines have immense hidden potential due to fuel flexibility, low emissions and maintenance. In recent years, the substantial pressure to address environmental issues has led people to focus more on green technologies, so most of the related applications of micro gas turbines use renewable energy like wind energy or biomass. Small-scale power generation can be applied in commercial and residential areas and areas with worse living conditions, such as rural or remote ones. And it is usually designed to exploit more waste heat for cooling/heating purposes. Anyway, there are still drawbacks exist. These turbines require high angular velocity and advanced electronics that can convert high-frequency electricity. The author surveyed distributed energy generation, biomass power plants and mini/micro gas turbines, some typical examples of small-scale power generation that are also stationary and have combustion processes. This application of stationary gas turbines is relatively more innovative and updated than others, so there are not many reliable researches posted online in recent years. This paper will reference all the researchers who want to work in this field.

The comparison and advantages with other engines and other aspects of Stirling engine in household appliances, to solve the problems caused by existing household appliances, realize the optimization of energy resources and achieve sustainability. A Stirling engine can work in reverse as a heat pump for heating or cooling if supplied with mechanical power. The ultra-low temperature refrigerator using the Stirling engine breaks through the traditional compressor refrigeration method in the noise, efficiency, energy consumption, stability, and other aspects of the long-term dilemma, creating a new situation of technological refrigeration. In the late 1930s, the Philips Corporation of the Netherlands successfully used the Stirling cycle in cryogenic applications. Experiments have been conducted using wind power driving a Stirling cycle heat pump for domestic heating and air conditioning. This paper mainly describes the application of the Stirling engine in household appliances and its advantages. The paper will explore the basic principle and efficiency of the Stirling engine and the use of household appliances.

The hybrid engine is a kind of emerging engine. It can simultaneously use an internal combustion engine and electric motor and other engine driving methods to improve fuel efficiency, reduce pollution emissions, extend the power system's life, improve performance, and have a series of significant advantages. However, hybrids are expensive to sell and maintain, have limited battery life, and can lose their fuel efficiency advantage at high speeds. On the opposite side, the internal combustion engine has a long history of traditional power engines, so it is easier to use, cheaper, and more mature, but it causes more pollution, poor fuel economy, and serious energy loss. These engines are two of the mainstream engines in the market at present. They each have different advantages and characteristics. In the choice of two different types, to combine the needs of users, comprehensive consideration, practical choice in line with the working environment of the engine. This paper aims to compare the advantages and disadvantages of hybrid and traditional internal combustion engines and analyze the reasons for these advantages and disadvantages and the impact of these advantages and disadvantages in detail.

Nowadays, nearly all large commercial aircraft are powered by gas turbine engines. Having been developed for about 80 years of engines applied on commercial aircraft, from low bypass ratio turbojet engines to high bypass ratio turbofan engines since the first turbojet engine was patented in 1930 by Frank Whittle, gas turbine engines still have a high potential to improve the performance. Currently, motor thermodynamic efficiency can still rise in the following decades; composite materials, for instance, gamma titanium aluminum and polymer matrix composites, are becoming widely used in airliner propulsion due to their lightweight and high-temperature capability. Accordingly, environmental issues related to gas emissions have also become vital due to the continued flourishing of commercial airliners. In this paper, the development of gas turbine engines applied on commercial airliners from low bypass ratio turbojet engine "Nene1" to high bypass ratio turbofan engine "GE9X," and the current advancement of jet engines applied will be discussed in order to gain possible improvement on the performance of jet engines. Current conditions and expectations of jet engines will be discussed with specific examples, focusing on efficiency, materials and manufacturing, and environmental issues. In the paper, the engines mentioned are all related to commercial aircraft.

A jet engine is a sophisticated machine that has revolutionized the aviation industry. It is a type of internal combustion engine that uses air as its oxidizer and fuel to produce thrust. The third law of motion, which states that there is an equivalent and opposite response to every action, governs how the engine functions. Compressed air is combined with fuel, ignited in the combustion chamber, and then expelled out of the jet engine at a high rate of speed to create propulsion. The development of jet engines has been a long and arduous process, with many different designs and configurations over the years. Early jet engines were inefficient, noisy, and prone to failure. However, technological advances have created more efficient and reliable engines in various applications, from commercial aviation to military aircraft and even spacecraft. The efficiency and reliability of jet engines have transformed air travel, enabling faster and more efficient travel over long distances. This has increased global connectivity, economic growth, and cultural exchange. However, jet engines also have environmental impacts, such as noise pollution and greenhouse gas emissions, which have led to the development of more environmentally friendly engines.