The purpose of this paper is to develop a novel nonlinear H∞ control approach for the nonlinear multivariable attitude tracking of rigid spacecraft.
Abstract
Purpose
The purpose of this paper is to develop a novel nonlinear H∞ control approach for the nonlinear multivariable attitude tracking of rigid spacecraft.
Design/methodology/approach
Based on the transformation of the attitude tracking problem into quaternion error stabilization, the feedback control law is developed by using the normal matrix control theory with the inverse‐additive perturbation description of systems uncertainties, and the Hamilton‐Jacobi‐Isaacs (HJI) partial differential inequality is employed for providing the nonlinear H∞ control criteria for the proposed control law. The onboard recursive least squares (RLS) estimation algorithm of inertia tensor is used for the further improving of the normal matrix property of the control system. The RLS algorithm is simple enough for the spacecraft borne computer. Computer simulation is performed to demonstrate the effectiveness of the control law proposed.
Findings
By the normal matrix control theory, the nonlinear H∞ control law for attitude tracking is developed without solving the HJI inequality and with the inflight estimation of inertia, the proposed control law is adaptive and robust to the variation of mass properties, and its normality is further improved.
Research limitations/implications
The paper is limited in rigid spacecraft with slowly changing mass property. The flexible influences are not considered.
Practical implications
The paper provides an alternative to the spacecraft researchers/engineers for developing the robust attitude control law with a simple structure and self‐tuning ability.
Originality/value
The paper is the first to provide a robust control based on the normal matrix approach, the HJI inequality, and the estimation of inertia.
Details
Keywords
Shijun Huang, Pengcheng Du and Yu Hong
With the continuous deepening of China's mixed-ownership reform, the participants in the reform have gradually expanded from state-owned enterprises to private enterprises…
Abstract
Purpose
With the continuous deepening of China's mixed-ownership reform, the participants in the reform have gradually expanded from state-owned enterprises to private enterprises. Whether state-owned equity participation in private enterprises can facilitate the development of environmental, social and governance (ESG) performance in private enterprises is a question that needs urgent examination. This study aims to investigate the impact of state-owned equity participation on the ESG performance of private enterprises.
Design/methodology/approach
Using Chinese listed companies as the research sample, this study uses econometric methods such as multiple regression to analyze the relationship between state-owned equity and the ESG performance of private enterprises. Additionally, it explores the underlying mechanisms and influencing factors of this relationship.
Findings
There is a significant inverted U-shaped relationship between state-owned equity and the ESG performance of private enterprises. Mechanism analysis reveals that resource effects and governance effects play a mediating role in this nonlinear relationship. Furthermore, the authors find that environmental regulation and managers' attention to the environment positively moderate the relationship between state-owned equity participation and ESG performance.
Practical implications
A reasonable equity structure is crucial for enhancing corporate ESG performance. Moderate state-owned equity participation helps to leverage resource integration and governance advantages, which will assist private enterprises in maximizing ESG performance and achieving sustainable development.
Social implications
In advancing the process of mixed-ownership reform, the government should maintain an appropriate proportion of state-owned equity to avoid excessive intervention in enterprise decision-making. At the same time, it should ensure that enterprises can genuinely undertake their social and environmental responsibilities while pursuing economic benefits. This is of great significance for promoting sustainable economic and social development.
Originality/value
This study integrates state-owned equity, ESG and nonlinear relationships into a single research framework. It explores the internal mechanisms and influencing factors of their relationship, overcoming the limitations of previous studies and provides a new perspective for understanding the impact of state-owned equity on corporate ESG performance.
Details
Keywords
Qin Kang, Yicheng Fan, Kun Zhang, Xiaolang Chen, Hongyu San, Yiqing Chen and Heming Zhao
With excellent mechanic properties and hydrogen embrittlement (HE) resistance, 12Cr2Mo1R(H) steel is suitable to make hot-wall hydrogenation reactors. However, longtime exposure…
Abstract
Purpose
With excellent mechanic properties and hydrogen embrittlement (HE) resistance, 12Cr2Mo1R(H) steel is suitable to make hot-wall hydrogenation reactors. However, longtime exposure to a harsh environment of high-pressure hydrogen at medium temperature in practical application would still induce severe hydrogen uptake and eventually damage the mechanical properties of the steel. The study aims to evaluate the HE resistance of the steel under different tensile strain rates after hydrogen charging and analyze the hydrogen effect from atomic level.
Design/methodology/approach
This research studied the HE properties of 12Cr2Mo1R(H) steel by slow strain rate tests. Meanwhile, the effect of hydrogen on the structures and the mechanical properties of the simplified models of the steel was also investigated by first-principle calculations.
Findings
Experimental results showed that after hydrogen pre-charging in this work, hydrogen had little effect on the microstructure of the steel. The elongations and reduction of cross-sectional area of the samples reduced a lot, by contrast, the yield and tensile strengths changed slightly. The 12Cr2Mo1R(H) steel was not very susceptible to HE with a maximum embrittlement index of about 20.00%. First principles calculation results showed that after H dissolution, lattice distortion occurred and interstitial H atoms would preferentially occupy the tetrahedral interstitial site in bcc-Fe crystal and increase the stability of the supercells. With the increase of H atoms added into the simplified model, the steel still possessed a good ductility and toughness at a low hydrogen concentration, while the material would become brittle as the concentration of hydrogen continued to increase.
Originality/value
These finds can provide valuable information for subsequent HE studies on this steel.
Details
Keywords
Ru-xin Nie, Kwai-sang Chin, Zhang-peng Tian, Jian-qiang Wang and Hong-yu Zhang
The purpose of this paper is exploring the effects of segment dynamic and temporal dynamic triggered by the COVID-19 pandemic on classifying service quality attributes, thereby…
Abstract
Purpose
The purpose of this paper is exploring the effects of segment dynamic and temporal dynamic triggered by the COVID-19 pandemic on classifying service quality attributes, thereby formulating improvement strategies to satisfy customers and respond to threats.
Design/methodology/approach
Given the dynamics of the attractive quality theory, this paper designs a framework with four phases by embedding techniques of text mining and deep learning based on evidence from online reviews.
Findings
This paper figures out dynamics of service quality attributes for distinct segments and their dynamic proportion along with different stages of the pandemic. Another finding demonstrates segment dynamic and temporal dynamic effects of sentiments toward service quality attributes on customer satisfaction under the impacts of pandemic. Classification results and improvement strategies are derived for varying segments at different pandemic situations.
Practical implications
This paper reveals dynamic effects on classifying service quality attributes, which contributes to assisting hospitality practitioners from different segments in improving service quality when facing with the challenges of crisis and potential risks.
Originality/value
Given hospitality industry is time- and segment-sensitive, the authors achieve the quantification of dynamics of attractive quality theory and extend it into hospitality marketing and crisis management from the perspective of dynamics with evidence from online reviews.
Details
Keywords
Xiang Qiu, Kun Zhang, Qin Kang, Yicheng Fan, Hongyu San, Yiqing Chen and Heming Zhao
This paper aims to study the mechanism of hydrogen embrittlement in 12Cr2Mo1R(H) steel, which will help to provide valuable information for the subsequent hydrogen embrittlement…
Abstract
Purpose
This paper aims to study the mechanism of hydrogen embrittlement in 12Cr2Mo1R(H) steel, which will help to provide valuable information for the subsequent hydrogen embrittlement research of this kind of steel, so as to optimize the processing technology and take more appropriate measures to prevent hydrogen damage.
Design/methodology/approach
The hydrogen diffusion coefficient of 12Cr2Mo1R(H) steel was measured by the hydrogen permeation technique of double electrolytic cells. Moreover, the influence of hydrogen traps in the material and experimental temperature on hydrogen diffusion behavior was discussed. The first-principles calculations based on density functional theory were used to study the occupancy of H atoms in the bcc-Fe cell, the diffusion path and the interaction with vacancy defects.
Findings
The results revealed that the logarithm of the hydrogen diffusion coefficient of the material has a linear relationship with the reciprocal of temperature and the activation energy of hydrogen atom diffusion in 12Cr2Mo1R(H) steel is 23.47 kJ/mol. H atoms stably exist in the nearly octahedral interstices in the crystal cell with vacancies. In addition, the solution of Cr/Mo alloy atom does not change the lowest energy path of H atom, but increases the diffusion activation energy of hydrogen atom, thus hindering the diffusion of hydrogen atom. Cr/Mo and vacancy have a synergistic effect on inhibiting the diffusion of H atoms in α-Fe.
Originality/value
This article combines experiments with first-principles calculations to explore the diffusion behavior of hydrogen in 12Cr2Mo1R(H) steel from the macroscopic and microscopic perspectives, which will help to establish a calculation model with complex defects in the future.
Details
Keywords
Jiawei Sun, Peng Yi, Hong-Yu Jia, Xiao-Shuang Yang, Yong-Jun Shi, Yancong Liu and Muming Hao
This paper aims to investigate the influence of sinusoidal texture (ST) with different morphology parameters on the corresponding tribological effects.
Abstract
Purpose
This paper aims to investigate the influence of sinusoidal texture (ST) with different morphology parameters on the corresponding tribological effects.
Design/methodology/approach
The STs with different amplitudes, ranging from 0.05 to 0.3 mm, and frequencies, ranging from 5 to 17.5, are fabricated using nanosecond pulsed laser equipment. The friction experiments and the finite element analysis method are combined to investigate the tribological properties, under dry friction conditions.
Findings
Test results show that when the amplitude is 0.15 mm and frequency is 10, ST surface has the lowest friction coefficient of 0.373, and exhibits great anti-friction effect. It also possesses a complete texture edge after friction. The friction reduction effect of ST with larger or smaller amplitude and frequency is worse.
Originality/value
The results of this study can provide a guidance for the design optimization of ST of reciprocating sliding contact surfaces, under dry friction conditions.
Details
Keywords
Osmud Rahman and Hong Yu
The purpose of this paper is to gain a deeper understanding of how income, cognitive age, physiological change and life-changing events may affect older consumers’ shopping…
Abstract
Purpose
The purpose of this paper is to gain a deeper understanding of how income, cognitive age, physiological change and life-changing events may affect older consumers’ shopping behaviours and preferences.
Design/methodology/approach
In-depth semi-structured interview was employed for this study. In total, 13 informants were recruited in Toronto, including 11 females and 2 males aged between 51 and 80 years. Content analysis and holistic interpretation were employed for data analysis.
Findings
According to the findings, price was a major concern to many informants regardless of their income level. The relationship between “feel age”, “look age”, or even “health age”, are not always positively correlated. The vast majority of the informants preferred shopping at the brick-and-mortar stores over online shopping. Some informants experienced difficulties or challenges in finding clothing that fit well due to the change of their body shapes. In addition, many informants needed to adjust their personal needs and buying priorities to cope with their changing personal situations and social roles.
Practical implications
Other than the price and mobility issues, older consumers encounter different challenges when they shop for different products. It is imperative for retailers, service providers and product developers to understand the older consumers’ changing needs, aspirations and challenges through diverse perspectives – the transition of social roles, physiological change and life-changing events.
Originality/value
Many prior studies are merely focused on one topic (e.g. cognitive age) or product category (e.g. clothing). Through this multidimensional and mixed categorical approach, new knowledge and insights can be generated and added to the current body of research.
Details
Keywords
Osmud Rahman and Hong Yu
The purpose of this paper is to gain an understanding of baby boomers’ physiological and psychological needs through clothing consumption.
Abstract
Purpose
The purpose of this paper is to gain an understanding of baby boomers’ physiological and psychological needs through clothing consumption.
Design/methodology/approach
A qualitative research approach was employed for this study. Data were collected from two generational segments: early baby boomers (1946–1954), and late baby boomers (1955–1964). In total, 13 informants aged from 53 to 71 years were participated in this study. Content analysis and interpretive approach were used for data analysis.
Findings
According to the findings, there are several reasons why the baby boomers shopped for clothing, including a way of stress relief or retail therapy, wardrobe update, replacement of worn-out garments, attractiveness of clothing styles and convenience. Style, fit, comfort and colour were the four most important product evaluative cues. Other than product cues, age appropriateness is an important factor for clothing consumption. Many informants were disappointed with their current body type, shopping experience and the industry offers.
Practical implications
Age-appropriate clothing can give wearers greater self-assurance/-gratification. If fashion designers create their products based on the baby boomers’ cognitive age, it would probably increase their customers’ acceptance and satisfaction.
Originality/value
The rapid growth of the aging population is a global phenomenon. Therefore, investigating the needs and challenges of the baby boomer generation is both timely and imperative. This study intended to offer new knowledge on the issues of baby boomers’ unmet needs, and provide insights and implications to fashion practitioners.