High-end Manufacturing Industry Research Articles

A Review of Magnetic Abrasive Finishing for the Internal Surfaces of Metal Additive Manufactured Parts

With the rapid development of high-end manufacturing industries such as aerospace and national defense, the demand for metal additive manufactured parts with complex internal cavities has been steadily increasing. However, the finishing of complex internal surfaces, especially for irregularly shaped parts, remains a significant challenge due to their intricate geometries. Through a comparative analysis of common finishing methods, the distinctive characteristics and applicability of magnetic abrasive finishing (MAF) are highlighted. To meet the finishing needs of complex metal additive manufactured parts, this paper reviews the current research on magnetic abrasive finishing devices, processing mechanisms, the development of magnetic abrasives, and the MAF processes for intricate internal cavities. Future development trends in MAF for complex internal cavities in additive manufactured parts are also explored; these are (1) investigating multi-technology composite magnetic abrasive finishing equipment designed for complex internal surfaces; (2) studying the dynamic behavior of multiple magnetic abrasive particles in complex cavities and their material removal mechanisms; (3) developing high-performance magnetic abrasives suitable for demanding conditions; and (4) exploring the MAF process for intricate internal surfaces.

Upstream Dependence of China’s High-End Manufacturing Sector on the International Market

Supply chain globalization is a distinctive feature of the manufacturing sector. However, the market environment is becoming more complex, and the vulnerability of the global supply chain is becoming more and more prominent. Assessing external dependence based on the intermediate products can more accurately identify the threats inherent in China’s manufacturing supply chain. This article aims to measure and verify the upstream dependence on the international market in China’s high-end manufacturing industry. UD is adopted to evaluate the degree of upstream dependence; CR8 is applied to measure the concentration of upstream intermediate products’ dependence on the eight largest economies. The results show that the upstream dependence of China’s high-end manufacturing sector on the international market increased from 0.08089 in 2017 to 0.11354 in 2022, growing by 40.36%. The upstream reliance on Asia and Europe is greater while displaying a lesser reliance on North America, Oceania, South America, and Africa. China’s high-end manufacturing sector exhibits a significant reliance on some upstream suppliers, including the Republic of Korea, Australia, Japan, Germany, the United States, and Russia. The concentration of the upstream dependence on the eight largest economies in the international market has increased from 0.03192 in 2017 to 0.04522 in 2022, but the share of the largest four economies decreased from 75.24% in 2017 to 65.29% in 2022. There are great gaps in the upstream dependence of the seven high-end manufacturing sectors.

WITHDRAWN: Digital twin-driven machining process for multi-process irregular-shaped parts manufacturing

With the advancement of high-end manufacturing industries, certain critical parts exhibit peculiar shapes and characteristics of multi-process manufacturing, which intensify milling difficulties and give rise to error propagation effects during the machining process. This necessitates machining systems to be adaptive to different working conditions and capable of real-time error analysis and optimization. Digital twin technology can create virtual replicas of physical entities to observe, analyze, and optimize the machining process. Therefore, this paper proposes a framework for digital twin-driven machining of multi-process irregular-shaped parts, consisting of preparation, processing, and optimization stages. In the preparation stage, a mapping relationship between the workpiece and machine tool motion coordinates is established to create a twin simulation environment consistent with actual operational parameters. In the processing stage, the digital thread dynamically updates the digital twin workpiece and machine tool status in real-time, analyzing the machining errors for each process to assess the finished quality. In the optimization stage, a cloud-based machining knowledge graph is constructed to enhance the precision of machining optimization decisions under different error sources and causes in the digital twin system. Finally, a case study of a typical multi-process irregular-shaped part machining task validates the reliability and superiority of the digital twin-driven method. The case study demonstrates that in a total of 260 machining processes, the digital twin-driven method improves machining accuracy by 40%, saves 34.9% of machining time, and alleviates 70% of machining downtime compared to existing machining methods.

Uncertainty analysis of motion accuracy on single-axis feed drive systems

The use of mechatronic integrated equipment, such as servo feed drive systems, has become increasingly important in high-end manufacturing, aerospace, and semiconductor industries. However, while advancements in modeling and analysis have improved deterministic feed systems, there is a lack of research into uncertain motion accuracy due to random factors in actual working conditions. This paper aims to address this issue by analyzing the uncertainty of motion accuracy in single-axis feed drive systems. Random factors already impact both positioning accuracy and repeatability, while dynamic errors are reflected in the mean and variance of following errors. The study also considers the impact of disturbance uncertainty, parameter uncertainty, and model uncertainty on motion accuracy. To investigate the impact of these sources of uncertainty on a six-degree-of-freedom linear motor feed system, a simulation example using the Monte Carlo simulation algorithm was utilized. The analysis revealed that uncertainty indeed has an impact on motion accuracy. This research will help identify and improve random errors in servo feed systems, ultimately leading to the development of strategies for reducing motion accuracy uncertainty and enhancing the accuracy and reliability of feed systems in high-end manufacturing, aerospace, and semiconductor industries.

Comparison of Hong Kong And Taiwan Economic Development in the Context of the Oil Crisis

Hong Kong and Taiwan are part of China and are similar in politics, economy, culture, etc. But in response to the two oil shocks in the 1970s, the two places showed different patterns of economic decline. Taiwan's economy reacted quickly to the oil shock, but the decline was more moderate, while Hong Kong's recession tended to lag global crises, but the reduction was more significant. From the perspective of industrial structure, this paper analyzes the differences in development strategies and industrial structure before the first oil strike and between them through case comparison. This paper finds that Taiwan's economic decline pattern was closely related to its vigorous development of the import substitution industry. In contrast, Hong Kong's industry and trade were less affected, but the rapid growth of finance and real estate at that time created economic instability. The author believes retaining a specific high-end manufacturing industry can stabilize the local economy. The conclusions of this paper can be used for reference in the economic transformation of developing regions.

The Enlightenment of Technology Introduction from Japan and South Korea on China

The improvement of the competitiveness of advanced manufacturing industry cannot be separated from the optimization and upgrading of industrial institutions. The optimization and upgrading of industrial institutions provide an ecosystem for the improvement of the competitiveness of advanced manufacturing industry. Only by starting from the low-end manufacturing industry can the optimization and upgrading of industrial structure provide assistance for the improvement of high-end manufacturing industry. The article analyzes how to optimize industrial institutions and enhance the competitiveness of industries based on the selection of technology introduction policies in industrial technological progress.

Phase Structure, Microstructure, Corrosion, and Wear Resistance of Al0.8CrFeCoNiCu0.5 High-Entropy Alloy

This study investigates the structure and corrosion behavior of the Al0.8CrFeCoNiCu0.5 high-entropy alloy prepared using non-consumable vacuum arc melting. XRD analysis identified BCC1 and BCC2 phases corresponding to (Fe-Cr) and Al-Ni, respectively, while the FCC phase aligned with Cu. SEM and EBSD observations confirmed an equiaxed grain structure with fishbone-like morphology at grain boundaries and modulated structures within the grains. The alloy exhibited minimal residual stress and strain. The alloy demonstrated a preferred orientation of grain growth along the <001> direction. Electrochemical testing in a 3.5% NaCl solution revealed a corrosion potential of −0.332 V and a corrosion current density of 2.61 × 10−6 A/cm2. The intergranular corrosion regions exhibited significant depletion of Al and Cu elements, with the corrosion products primarily consisting of Al and Cu. Al and Cu elements are susceptible to corrosion. The wear scar width of Al0.8CrFeCoNiCu0.5 high-entropy alloy is 1.65 mm, which is less than 45# steel, and high-entropy alloy has more excellent wear resistance. Given its unique attributes, this high-entropy alloy could find potential applications in high-end manufacturing industries such as the aerospace engineering, the defense industry, energy production, and chemical processing where high corrosion resistance and wear resilience are crucial.

The Research of the Evolution and Development Direction on Chinese Innovation Policy under the New Economic Momentum

The Chinese government has been pursing upgrading its position in global industrial chain and supply chain system to enter a higher stage since the opening policy, even though the external environment is deteriorating constantly. And this intention is more obvious and accelerating without any stop in recent years. Objectively say this is one of the most exact and direct reasons why relationship of China-US is falling and is fulling of conflicts. Since March 2018, the US government has successively initiated and signed trade sanctions against China, what is indifferent from the past, those sanctions which essence is to suppress the ambition and plan of China's at the high-end manufacturing industry through trade and investment barriers, to curb China's rise. Meanwhile, various risks are emerging in the world, and the uncertainty factors brought about by the war are rising significantly, and public health security is still a potential threat to the world economy in the post epidemic era. In this context, in the face of the constant conflict between China and the United States in trade, Chinese enterprises can only transform and upgrade their innovation capabilities to become the best way to escape from vicious competition. Therefore, this paper through conducts a horizontal comparative study of China's innovation policy system since the reform and opening by using the trichotomy method, with reference to the research on the development process of innovation policy systems of major innovation countries in the world. At the same time, it objectively analyses and evaluates the achievements and problems of China's current independent innovation policy in practice. Furthermore, when China's economic momentum entered the critical period of transformation, that is, under the background that China will leap over the middle-income trap and enter the ranks of moderately developed countries, the paper analysed and concluded the core position of innovation in China's future economic momentum transformation and development, thus making a rational prediction of China's future economic development trend from the analysis of international economic trends against the critical moments of increasing global instability.

Research on the Analysis and Prediction Model of Machining Parameters of Titanium Alloy by Abrasive Belt

As a high-performance and difficult-to-machine material for the manufacture of blades, titanium alloys are increasingly being used in high-end manufacturing industries such as aerospace and aircraft. As engineering applications become more demanding, so do the requirements for precision. However, to date, the choice of blade grinding parameters is still mainly dependent on the traditional “trial cut” and “experience” method, making the processing efficiency low and the quality of processing difficult to be guaranteed. In order to achieve the requirements of high precision and low surface roughness of the workpiece, to get rid of the status quo of relying on manual decision-making, and to achieve reasonable prediction and control of surface quality, this paper proposes to establish a theoretical prediction model for surface roughness of titanium alloy by abrasive belt grinding, and to analyze the influence of the main process parameters on surface roughness during the grinding process through experiments. A theoretical prediction model for surface roughness was developed. The experimental results show that the model has certain accuracy and reliability, and can provide guidance for the high-precision prediction of the surface roughness of ground titanium alloy blades, which has strong practical significance in engineering.

Urban Ecological Environment Quality Evaluation and Territorial Spatial Planning Response: Application to Changsha, Central China.

Scientific territorial spatial planning is of great significance in the realization of the sustainable development goals in China, especially in the context of China's ecological civilization construction and territorial spatial planning. However, limited research has been carried out to understand the spatio-temporal change in EEQ and territorial spatial planning. In this study, Changsha County and six districts of Changsha City were selected as the research objects. Based on the remote sensing ecological index (RSEI) model, the spatio-temporal changes in the EEQ and spatial planning response in the study area during 2003-2018 were analyzed. The results reveal that (1) the EEQ of Changsha declined and then rose between 2003 and 2018, showing an overall decreasing trend. The average RSEI declined from 0.532 in 2003 to 0.500 in 2014 and then increased to 0.523 in 2018, with an overall decrease of 1.7%. (2) In terms of spatial pattern changes, the Xingma Group, the Airport Group and the Huangli Group in the east of the Xiangjiang River had the most serious EEQ degradation. The EEQ degradation of Changsha showed an expanding and polycentric decentralized grouping pattern. (3) Massive construction land expansion during rapid urbanization caused significant EEQ degradation in Changsha. Particularly, the areas with low EEQ were concentrated in the areas with concentrated industrial land. Scientific territorial spatial planning and strict control were conducive to regional EEQ improvement. (4) The prediction using the urban ecological model demonstrates that every 0.549 unit increase in NDVI or 0.2 unit decrease in NDBSI can improve the RSEI of the study area by 0.1 unit, thus improving EEQ. In the future territorial spatial planning and construction of Changsha, it is necessary to promote the transformation and upgrading of low-end industries into high-end manufacturing industries and control the scale of inefficient industrial land. The EEQ degradation caused by industrial land expansion needs to be noted. All of these findings can provide valuable information for relevant decision-makers to formulate ecological environment protection strategies and conduct future territorial spatial planning.

Research on measurement and disequilibrium of manufacturing digital transformation: Based on the text mining data of A-share listed companies

<abstract> <p>Quantitative analysis of digital transformation is an important part of relevant research in the digital field. Based on the annual report data of China's manufacturing listed companies from 2011 to 2019, this study applies cloud computing to the mining and analysis of text data, and uses the Term Frequency-Inverse Document Frequency method under machine learning to measure the digital transformation index value of manufacturing enterprises. The results show that: (1) On the whole, the current pace of digital transformation of manufacturing enterprises continues to accelerate, and the digital transformation of manufacturing has gradually spread from the eastern coastal areas to the central and western inland areas. (2) In horizontal comparison, among the five types of "ABCDE" digital modules constructed, artificial intelligence develops the fastest, cloud computing index value is second, and block chain value is the smallest. In vertical comparison, the leading provinces such as Beijing, Guangdong, and Shanghai have certain stability and a solid leading position, and there are occasional highlights in the central and western provinces. (3) In terms of polarization distribution, the digitalization of the manufacturing industry has obvious multi-peak patterns, showing the phenomenon of multi-polarization of digital services. The eastern region has both aggregate advantages and equilibrium disadvantages. (4) In terms of industry differences, the level of digital transformation in the high-end manufacturing industry is significantly higher than that in the mid-end and low-end industries. On the ownership attributes of enterprise digital transformation, private enterprises are the highest, followed by foreign-funded enterprises, and state-owned enterprises are the lowest. This research provides theoretical enlightenment and factual reference for manufacturing enterprises to carry out digital activities.</p> </abstract>

Does the Belt and Road Initiative promote industrial upgrading and rationalisation and adjustment along the route?

This study uses data from 30 provinces and cities from 2010-2019 to examine the role of the Belt and Road Initiative (BRI) on industrial restructuring and upgrading in Chinese provinces and cities along the route using the Difference-in-differences method. The results found that participation in BRI construction is mainly under favorable policies to ensure that the tertiary sector can be strongly supported for development by stabilizing the macroeconomic situation, improving infrastructure construction, attracting surplus labor to the tertiary sector and strengthening technological innovation. BRI makes the industries tend to be advanced, and the key provinces develop tertiary industries and high-end manufacturing industries when participating in BRI construction and development, take advantage of policies to strengthen foreign trade through various ways, accelerate high-quality development of service industries, and achieve innovation and upgrading. At the same time, BRI can promote the rationalisation of industrial structure, which as an inverse indicator, the initiative makes a significant reduction and promotes the industrial structure to be more in line with the local economic development. The findings of the study provide theoretical support for China's future comprehensive deepening reforms.

Investigation of an Output Voltage Harmonic Suppression Strategy of a Power Quality Control Device for the High-End Manufacturing Industry.

Due to the influence of nonlinear loads, power quality control devices under the traditional double closed-loop control strategy suffer from a large output voltage harmonic distortion rate and a slow harmonic suppression response and cannot meet the high-quality power supply requirements of high-end manufacturing. A compound control strategy based on voltage feedback and current feed-forward is proposed to solve the voltage quality problem under a nonlinear load. Firstly, based on the mathematical model of power quality control device, the working principle and voltage current coupling relationship are analyzed. Then, an output voltage compound control strategy based on feed-forward and feedback is proposed, and the harmonic suppression mechanisms are deduced and analyzed. Finally, simulation and experimental results are presented to show that, compared with the traditional double closed-loop control strategy, the harmonic suppression effect of the composite control strategy proposed in this paper can be increased by 2.2%, and the response time is decreased to 100 ms.

Study on preparation of composite carbon rod for high-power electrode from coke with different structural characteristics

Different from lithium-ion batteries, composite carbon rod for high-power electrode was widely used in high-end manufacturing industry due to its good conductivity and low CTE. In this study, semi cokes with different structural characteristics was used as aggregate and coal tar pitch was adopted as binder and impregnant to prepare composite carbon rod for high-power electrode, and the bonding and impregnation behavior was also investigated. It was found that calcination promoted ordered stacking of planar aromatic lamellae of acicular domain texture and aggravated the structural defects of mosaic texture. Coal tar pitch with low aromaticity and high toluene insoluble (TI) as bonded and impregnated pitch possessed higher adhesion but low weight gain ratio after calcination. While higher TI content of coal tar pitch enhanced the weight gain ratio, but the adhesion of composite carbon rod declined. In addition, the carbonaceous sheets derived from coal tar pitch gradually extended and covered the surface of orderly graphited sheets generated from acicular domain texture and contributed to the lowest CTE of 1.43 * 10−6·℃−1 as well as the lowest specific resistance of 6.03μΩ·m. While the structural defects and voids generated from disordered mosaic texture could not be completely filled, thereby resulting in highest CTE of 2.20 * 10−6·℃−1 and highest specific resistance of 9.55μΩ·m.

Deep learning-based monitoring of surface residual stress and efficient sensing of AE for laser shock peening

• A multi-channel acoustic emission real-time efficient signal detection method and acquisition system. • A novel spatio-temporal complementary model (CNN-LSTM) for fusion of time-varying AE signal. • Dual circulation LSTM explains the decay mechanism of AE using temporal sampling points. • Stronger correlation between information from AE attenuation profile and surface quality. Laser shock peening (LSP) is one of the main anti-fatigue technologies in high-end manufacturing industries. However, guaranteeing its quality consistency is difficult due to its process complexity. Acoustic emission (AE) is a promising solution to accurately monitoring the surface quality of LSP, although, the large scale of monitoring data is still challenging for industrial applications. This paper studied the in-situ evaluation of surface residual compressive stress (SRCS) for 7075 aluminum alloy in LSP and the efficient sensing of AE based on deep learning methods. Firstly, a monitoring system of LSP with four types of AE sensors was developed in order to simultaneously acquire both the ultra-high and ultra-low amplitude of shock wave. The performance of those sensors is further quantitatively evaluated via long-short term memory (LSTM). Then, a new spatio-temporal parallel CNN-LSTM model for SRCS classification was proposed and experimentally validated to outperform CNN and LSTM after parameters optimization. Finally, aiming to efficient sensing of AE, the importance of different frames of AE signal was analyzed by means of the proposed dual circulation LSTM (DC-LSTM) model, which can accurately locate the key frame of time series signal. Besides, the effects of different frames of AE on classification performance was discussed. It was found that the broadband AE sensor without attenuator shows the highest classification accuracy, while the fast decay stage of AE signal has more contribution to the SRCS classification. This paper provides guidance for real-time non-destructive evaluation of residual stress via AE in laser manufacturing.

Population-land urbanization and comprehensive development evaluation of the Beijing-Tianjin-Hebei urban agglomeration.

As the main form of the new urbanization strategy, urban agglomeration promotes inter-regional economic development, population flow, and industrial cooperation. It is not only an important platform for the country to participate in international competition, but also an important carrier to explore the multiple influencing factors of urbanization. Based on the Beijing-Tianjin-Hebei urban agglomeration, the temporal and spatial characteristics of its evolution from 1990 to 2020 are analyzed by using the models of urban evolution and industrial transfer. The results show that at the level of urban land use evolution intensity, Beijing > Tianjin > Hebei, and the evolution of urban land use showed an obvious pattern of concentration of resources in central cities (districts) and weak development in sub-central cities (counties). The overall level of urban sprawl showed a downward trend, and only 0.50% of districts and counties were in the stage of high sprawl. Before 2010, the urban sprawl of Beijing, Tangshan, and southern Hebei province remained at a high level, and after 2010, the urban sprawl of central Hebei province remained at a high level. In terms of comprehensive development, the index of cities decreased, including Beijing, Tianjin, and Tangshan, while the index of cities increased including Shijiazhuang, Handan, Xingtai, and Baoding. There is a trend of agglomeration and diffusion of regional industries in geographical space. Middle- and high-end manufacturing industry and service industry gather in the first city, and middle- and low-end processing industry, labor-intensive industry, and agriculture move to surrounding cities. The research results can provide policy suggestions for the coordinated development of regional integration in developing countries.

China Transport Supply Chain Risk Management Challenges Face to COVID-19 Analysis

The international COVID-19 outbreak at the beginning of 2019 has had a huge influencing factor on lot of global and local manufacturing transportation chains, and triggered a continuous risks of logistics chains breakage by the way the COVID-18 pandemic has revealed the weakness of intercontinental supply chains arising from initial raw material scarcity, mass production and transportation disruption, and human being isolation. Among them, the short-term and medium-term and long-term impacts include encouraging companies to improve the flexibility of supply chains by constructing supply chains digital platforms, supply chains diversification systems and supply chains early warning system in the short, medium and long term, the global supply chains layout will change from internationalization to regionalization, and some high-end manufacturing industries will have a backflow trends. The risks associated with global supply chains management have created a discourse among practitioners and academics. Supply chains risk management is an integral function of the supply chains networks. Supply chains risks management have increasingly becoming a more popular research area recently, when COVID-18 appeared regionally, internationally and globally. In the article there are presented different calculation equations beginning from risk assessment during transportation and finishing by risk modeling, there are important factors influencing logistics and mainly supply chains when different types of risks appeared during COVID-22 transportation time.

China Transport Supply Chain Risk Management Challenges Face to Covid-19 Analysis

The international COVID-19 outbreak at the beginning of 2019 has had a huge influencing factor on lot of global and local manufacturing transportation chains, and triggered a continuous risks of logistics chains breakage by the way the COVID-18 pandemic has revealed the weakness of intercontinental supply chains arising from initial raw material scarcity, mass production and transportation disruption, and human being isolation. Among them, the short-term and medium-term and long-term impacts include encouraging companies to improve the flexibility of supply chains by constructing supply chains digital platforms, supply chains diversification systems and supply chains early warning system in the short, medium and long term, the global supply chains layout will change from internationalization to regionalization, and some high-end manufacturing industries will have a backflow trends. The risks associated with global supply chains management have created a discourse among practitioners and academics. Supply chains risk management is an integral function of the supply chains networks. Supply chains risks management have increasingly becoming a more popular research area recently, when COVID-18 appeared regionally, internationally and globally. In the article there are presented different calculation equations beginning from risk assessment during transportation and finishing by risk modeling, there are important factors influencing logistics and mainly supply chains when different types of risks appeared during COVID-22 transportation time.

Composite light ropes model-based dynamics force prediction model of high speed dry milling UD-CF/PEEK considering size effect

As an emerging material, Carbon fiber reinforced polyetheretherketone (CF/PEEK) is widely used in aviation, automotive, sports products, medical equipment and other high-end manufacturing industries due to its high shock resistance, thermostability, and recyclability. However, its dry-machining is an unclear dynamic material removal process which limits the machining efficiency and surface quality. To this end, we first presented composite light ropes model in machining composites considering size effect. Based on composite light ropes model, cutting region is affected by bending, stretching, pressing, bouncing and delamination, as the cutting mechanisms of carbon fiber and matrix are different. The carbon fibers distribution in chip is first introduced into the model to confirm the fiber deformation at different position. Based on composite light ropes model and elastic-plastic theory, the cutting force prediction model is obtained. To complete the model, the free-damped vibration force prediction model is established in empty cutting stage. The dynamics force prediction model is proofed with high prediction accuracy. Besides, the influences of cutting parameters on cutting and vibration force are analyzed by nonlinear regression analysis. It demonstrated that size effect is of great importance in establishing cutting force prediction model and revealing cutting mechanisms of CF/PEEK.

Sustainable Development Research of Green Smart Park in High-End Manufacturing Based on Internet of Things.

During the transition from industrial production to intelligent, there are still a large number of manufacturing industries in the traditional production mode. The problems of slow information transmission, difficult integrated production management, and complicated process parameter control have led to disconnect decision-making from actual production. In addition, the current manufacturing industry is more of a traditional management method, and the upgrade and iteration speed are slow, and it is not combined with the technology of the Internet of Things. Therefore, the purpose of this article is to use the Internet of Things monitoring technology to explore the improvement of high-end manufacturing and analyze the problems and solutions in the process of consistency of ecological environment and economic effects. This article will use the research methods of specific problems and specific analysis to compare the data and draw conclusions. This article will discuss the technical mechanism of the Internet of Things monitoring and introduce the collection and data of production status data of each station equipment in the production workshop during the production process: improving the current production model, learning foreign experience at the same time, quickly carrying out load curve and data center data accumulation on the service capabilities of the park, verifying multiple operating models, and simultaneously exploring new management models. Based on comparative advantage analysis, the study draws similarities and differences in the development of high-end manufacturing industries at home and abroad, learns advanced experience, proposes improved methods and paths, combines new environmental protection paths, and finally proposes energy operation in the park. Build a green and intelligent park to provide a theoretical reference for sustainable development. The research results show that computer monitoring technology and methods have effectively improved the production environment of high-end manufacturing, combined with the development status of the existing ecological and intelligent composite production system; the infrastructure construction of industrial parks in the new era, IT support, services, manpower resources, and industries has developed rapidly.