Search results

The purpose of this paper was to synthesise a thermally expandable microsphere (TEMS) with fast thermal response property and small expansion temperature range, and investigate the factors affecting the expansion properties of the microspheres.

A new kind of TEMS with fast thermal response property was synthesised by suspension polymerisation method, using acrylonitrile, ethyl methacrylate and methacrylic acid as the main monomers; Mg(OH)₂ as the main dispersing agent; and isooctane or n-hexane or n-pentane as the blowing agent.

The TEMS possessed the best expansion capacity when encapsulated isooctane and n-hexane were about 18.5 Wt.%. The expansion process of the TEMS could be finished by raising the temperature to 18°C from the expansion onset, much less than the reported 30-50°C. The morphology of the TEMS turned from sphere to irregular concave shape following the content increase of the blowing agent.

A new kind of TEMS composed of acrylonitrile/ethyl methacrylate/methacrylic acid as the polymer shell was synthesised. These TEMS showed the fastest thermal response speed reported.

Innovation ambidexterity is crucial for fostering growth and gaining a competitive advantage in small and medium enterprises (SMEs). Previous research indicates that achieving a balance between exploration and exploitation is a multifaceted phenomenon occurring across various levels. This paper aims to examine the influence of individual, organizational and institutional factors on the ambidextrous innovation of Chinese niche leaders using a configurational perspective.

This study uses secondary data collected from 69 Chinese niche leaders in the new equipment manufacturing industry. The authors use fuzzy-set qualitative comparative analysis to investigate how owner openness, age, digitization, the formal institutional environment and the informal institutional environment jointly influence innovation ambidexterity.

By using fuzzy set analysis, this study categorizes combinations of interdependent factors that promote innovation ambidexterity. In particular, the authors pinpoint three configurations that foster high innovation ambidexterity and two configurations that lack such high levels of innovation ambidexterity. The analysis results suggest that innovation paradoxes in SMEs are linked to a nested system comprising leadership, organizational factors and the institutional environment.

This study elucidates the mechanism of innovation ambidexterity through a configurational perspective. This research proposes and validates a framework that enables SMEs to develop ambidextrous innovation capabilities, thereby integrating organizational ambidexterity theory and shedding light on the intricately complex nature of innovation ambidexterity.

This study aims to explore how relational and contractual governance affect crowdsourcer satisfaction under boundary conditions, including internal (i.e. task complexity) or external (i.e. environmental complexity) factors.

We empirically validate the hypotheses using survey data collected from 255 crowdsourcers on a leading platform (i.e. Zhubajie.com). Partial least squares technique and hierarchical regression analysis are used to test the research model.

Both forms of governance mechanisms positively affect crowdsourcer satisfaction. Task complexity negatively moderates the linkage of relational governance and crowdsourcer satisfaction. However, environmental complexity weakens the positive effect of contractual governance but enhances the effect of relational governance on satisfaction.

This study deepens the current understanding of governance mechanism in crowdsourcing by discovering the effectiveness of contractual and relational governance. We also contribute to the governance and crowdsourcing literature by revealing the mechanisms of how governance takes effect under task and environmental complexities.

This paper aims to improve the anti-interference ability of the airborne radar stabilization platform, especially the ability to suppress continuous disturbance under complex air conditions to ensure the clarity and stability of airborne radar imaging.

This paper proposes a new active disturbance rejection control (ADRC) strategy based on the cascade extended state observer (ESO) for airborne radar stabilization platform, which adopts two first-order ESOs to estimate the angular velocity value and the angular position value of the stabilized platform. Then makes the error signal which subtracts the estimated value of ESO from the output signal of the tracking-differentiator as the input signal of the nonlinear state error feedback (NLSEF), and according to the output signal of the NLSEF and the value which dynamically compensated the total disturbances estimated by the two ESO to produce the final control signal.

The simulation results show that, compared with the classical ADRC, the ADRC based on the cascade ESO not only estimates the unknown disturbance more accurately but also improves the delay of disturbance observation effectively due to the increase of the order of the observer. In addition, compared with the classical PID control and the classical ADRC, it has made great progress in response performance and anti-interference ability, especially in the complex air conditions.

The originality of the paper is the adoption of a new ADRC control strategy based on the cascade ESO to ameliorate the anti-interference ability of the airborne radar stabilization platform, especially the ability to suppress continuous interference under complex air conditions.

This paper aims to study a disturbance rejection controller to improve the anti-interference capability and the position tracking performance of airborne radar stabilized platform that ensures the stability and clarity of synthetic aperture radar imaging.

This study proposes a disturbance rejection control scheme for an airborne radar stabilized platform based on the active disturbance rejection control (ADRC) inverse estimation algorithm. Exploiting the extended state observer (ESO) characteristic, an inversely ESO is developed to inverse estimate the unmodeled state and extended state of the platform system known as total disturbances, which greatly improves the estimation performance of the disturbance. Then, based on the inverse ESO result, feedback the difference between the output of the tracking differentiator and the inverse ESO result to the nonlinear state error feedback controller (NLSEF) to eliminate the effects of total disturbance and ensure the stability of the airborne radar stabilized platform.

Simulation experiments are adopted to compare the performance of the ADRC inverse estimation algorithm with that of the proportional integral derivative controller which is one of the mostly applied control schemes in platform systems. In addition, classical ADRC is compared as well. The results have shown that the ADRC inverse estimation algorithm has a better disturbance rejection performance when disturbance acts in airborne radar stabilized platform, especially disturbed by continuous airflow under some harsh air conditions.

The originality of this paper is exploiting the ESO characteristic to develop an inverse ESO, which greatly improves the estimation performance of the disturbance. And the ADRC inverse estimation algorithm is applied to ameliorate the anti-interference ability of the airborne radar stabilization platform, especially the ability to suppress continuous interference under complex air conditions.

Under the background of economic and technological globalization, all countries will pay attention to science and technology innovation policies. At this time, the era of innovation policy plays an important role. In order to thoroughly implement the spirit of the 19th National Congress of the Communist Party of China, earnestly innovate development concepts and strengthen the key supporting role of scientific and technological innovation for social development.

The research will make an in-depth study on the policy of scientific and technological innovation, take the change trend of the number of laws and regulations and the analysis of the basic content as the entry point, and classify it from five different aspects, such as the policy of scientific and technological system and mechanism, the policy of financial guidance, the policy of technological innovation of enterprises, the policy of scientific and technological talents, and the policy of intellectual property.

Through the comparison of the development history of science and technology policies at home and abroad, the development history of science and technology innovation policies under the special national conditions of China is obtained. Combining with the relevant basic theories of science and technology innovation system, designing from the publishing department, main content, and implementation subject, constructing a synergistic science and technology innovation system of “government, industry, university and research,” and forming an “integration of supply and demand” technology innovation framework will guide the development of China's science and technology innovation in the future.

The authors construct the policy framework of science and technology collaborative innovation based on the concept of science and technology innovation policies. The framework has realistic significance for its future development.

Library intelligence institutions, which are a kind of traditional knowledge management organization, are at the frontline of the big data revolution, in which the use of unstructured data has become a modern knowledge management resource. The paper aims to discuss this issue.

This research combined theme logic structure (TLS), artificial neural network (ANN), and ensemble empirical mode decomposition (EEMD) to transform unstructured data into a signal-wave to examine the research characteristics.

Research characteristics have a vital effect on knowledge management activities and management behavior through concentration and relaxation, and ultimately form a quasi-periodic evolution. Knowledge management should actively control the evolution of the research characteristics because the natural development of six to nine years was found to be difficult to plot.

Periodic evaluation using TLS-ANN-EEMD gives insights into journal evolution and allows journal managers and contributors to follow the intrinsic mode functions and predict the journal research characteristics tendencies.

This article describes structural developments of public expenditures in China in the past 30 years and demonstrates an increasing public's need for services in areas of education, health care, social security, and housing. Starting with a theory explaining the need to adjust the spending structure, the article specifies a proper proportion of public service expenditures in total governmental spending and discusses a possible path to this spending structure.

The former residences of historical figures are typical landscape elements of historic districts, which are characterised by the styles of these residences and spiritual historical figures cultures. The purpose of this paper is to determine how the former residences respond once the historical figures living there have passed.

The history of human culture and progression of urban construction – which are submerged in societal transformation – is recorded for old Beijing city. Narrative space theory is used and methods such as a content analysis, map overlay and the Geographic Information System are employed to analyse the selected 300 former residences of historical figures in old Beijing city.

The results are as follows: the political setting played a key role in the evolution process, three political narrative areas in the inner city and one cultural narrative area in the outer city form the narrative spatial structure of the former residences of historical figures, “government construction” and “resident construction” are the main reasons for the loss and destruction of narrative spaces and ordinary life is an important channel for showcasing the history of former residences. The narrative spaces of these residences carry double histories, namely, the development of human history and of city construction.

Different from former studies that focus on the preservation of the single historical building, this study explores the integral logic of historic buildings in the whole city through narrative space theory to get a combination of culture and space.

To obtain an optimized microarc oxidation (MAO) coating on magnesium alloy from an environmentally‐friendly electrolyte free of Cr^6 + and PO₄³⁻ and to investigate the influence of oxidation potential on the morphology, composition, structure, and other properties such as micro‐hardness and corrosion resistance.

A constant potential regime was applied to produce the coatings and scanning electron microscopy, energy dispersive spectroscope, X‐ray diffraction, hardness testing and electrochemical methods were used to study coating properties.

The results clearly show that oxidation potential plays an important role in the formation of coating structure and properties. The MAO coating is smooth and white and consists of two layers. The external layer is loose and porous and enriched in Al and Si. Moreover, the content of Al and Si increase with operated potential. The inner layer is compact and the content of Al and Si are lower than are those of the external layer. The coating is composed of several phases: the main phase is MgAl₂O₄/MgO, and the minor phase is Al₂O₃/SiO₂ when the potential is higher. The micro‐hardness of the coating obtained a maximum at a potential of 45 V, as does the corrosion resistance.

This paper provides information relating to MAO technology and the morphology, structure and properties of MAO coatings.