Fu-Wang Yang, Jiang-Min Huang, Guan-Jun Zhang, Chenxi Zhang, Dong-Lan Sun, Nan-Feng Gao and Shouzhi Yi
The phosphorus and zinc contained in zinc dialkyl dithiophosphate (ZDDP) caused severe environment pollution and catalyst poison. Thus, the phosphorus-free additive, such as…
Abstract
Purpose
The phosphorus and zinc contained in zinc dialkyl dithiophosphate (ZDDP) caused severe environment pollution and catalyst poison. Thus, the phosphorus-free additive, such as borate esters, has become one of studying hot topics in the area of oil additive. However, the stability of hydrolysis greatly limited the use of borate esters. The purpose of this paper is to improve the stability of hydrolysis by synthesizing a new kind of N-containing heterocyclic borate ester (MTTDB) as a lubricant additive.
Design/methodology/approach
The tribological properties of novel borate ester (MTTDB) as an additive in the base oil were studied by a four-ball machine. The element composition and chemical state of the tribofilm were investigated by scanning electron microscopy, energy dispersive spectrometer and X-ray photoelectron spectroscopy.
Findings
The results showed that the base oil lubricated by MTTDB exhibited high hydrolytic stability, good anti-wear property and excellent extreme pressure performance. When 2.5 per cent MTTDB was added into the 100N base oil, the smallest wear scar diameter (0.46 mm) was obtained. Furthermore, the decomposed borate ester, organic sulfide adsorbed on the worn surface was detected, and S element reacted with the steel surface and generated FeSO4, both of which contributed to the formation of the tribofilm.
Originality/value
Based on N-containing heterocyclic compounds, for instance, thiadiazole derivatives, introducing nitrogen and sulfur elements into borate ester, a new kind of N-containing heterocyclic borate ester (MTTDB) exhibited excellent property in hydrolysis stability, friction-reducing, anti-wear and extreme pressure. This synthesized method would be helpful for the borate ester used as additive in engine oil, gear oil and other industrial lubricants.
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Wangyu Liu, Dong Sun, Aimin Tang and Mingke Li
Hydrogel is an excellent material for the fabrication of porous scaffold by mask-prototyping method. Different from the common commercial resin, hydrogel is hydrophilic and…
Abstract
Purpose
Hydrogel is an excellent material for the fabrication of porous scaffold by mask-prototyping method. Different from the common commercial resin, hydrogel is hydrophilic and hyperelastic, so that it cannot bear the conventional post-curing process to improve its mechanical properties. The purpose of this paper is to put forward a method to improve the curing bonding strength at the weak juncture of the porous hydrogel scaffold.
Design/methodology/approach
The working curve of the resin was obtained through the single layer cure experiment, and the energy accumulation model has been set up by MATLAB. Aimed at the specificity of material, a new method of partial curing on different kind of structure has been proposed. Under the same condition, only the tn2 needs to be changed to fabricate different test specimens with different accumulated energy between two layers. The tensile test is carried out with the authors’ preferred equipment.
Findings
The analysis reveals that accumulated energy can be changed by adjusting the key parameters, and the tensile test shows that when the accumulated energy is bigger, the ultimate tensile strength is higher.
Research limitations/implications
Subject to the equipment accuracy and specificity of material, some errors coming from the experiment and test might exist, but the authors believe they will not change their findings and conclusions in this paper.
Practical implications
The research provides a method which is different from the common methods but friendlier to improve the bonding strength of the hydrogel scaffold.
Social implications
This work can help to adjust the mechanical property of the scaffold used in tissue engineering.
Originality/value
This method can improve the bonding strength at weak juncture and give a direction for the design of porous scaffold.
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Bruno S. Sergi, Elena G. Popkova, Natalia Vovchenko and Marina Ponomareva
This chapter elaborates on the perspectives of financial development of countries of Central Asia and China through cooperation with Russia. The authors determine financial…
Abstract
This chapter elaborates on the perspectives of financial development of countries of Central Asia and China through cooperation with Russia. The authors determine financial resources for the development of the countries of Central Asia and China and figure out possible scenarios for attracting additional financial resources and conclude that financial resources have a decisive role in socioeconomic development. It is substantiated that the increase and expansion of cooperation with Russia are the preferable scenario for attracting additional financial resources. The authors recommend expanding cooperation with Russia within the implementation of the selected optimal scenario are given.
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Sustainable energy like renewable energy plays a critical role in achieving sustainable development goals including energy security in emerging economics. BRICS (Brazil, Russia…
Abstract
Sustainable energy like renewable energy plays a critical role in achieving sustainable development goals including energy security in emerging economics. BRICS (Brazil, Russia, India, China and South Africa) constitutes about 23% of the world’s GDP, 40% of the world’s population and 36% share of the supply of primary energy in the world. Obviously the Bloc has tremendous potential in influencing the global sustainable clean energy transition with the advantages like lowering the costs of renewable, boosting employment in the sector of green energy, enhancement of energy security and improvement of local air quality. Despite the existence of varieties of renewable energy resources in the BRICS economies, renewable energy resources are found underdeveloped. The major objectives of this chapter are to assess progress of different forms of energy especially renewable energy, impact of development of renewable energy on carbon emission and policy issues in renewable energy development in the context of sustainable energy development of BRICS countries.
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Yonghua Li, Hao Yin and Qing Xia
This study aims to research the influence of non-probabilistic design variables on interval robust optimization of electric multiple units (EMU) brake module, therefore obtain the…
Abstract
Purpose
This study aims to research the influence of non-probabilistic design variables on interval robust optimization of electric multiple units (EMU) brake module, therefore obtain the reasonable of design variables of the EMU brake module.
Design/methodology/approach
A robust optimization model of the EMU brake module based on interval analysis is established. This model also considers the dimension tolerance of design variables, and it uses symmetric tolerance to describe the uncertainty of design variables. The interval order relation and possibility degree of interval number are employed to deal with the uncertainty of objective function and constraint condition, respectively. On this basis, a multiobjective robust optimization model in view of interval analysis is established and applied to the robust optimization of the EMU brake module.
Findings
Compared with the traditional method and the method proposed in the reference, the maximum stress fluctuation of the EMU brake module structure is smaller after using the method proposed in this paper, which indicates that the robustness of the maximum stress of the structure has been improved. In addition, the weight and strength of the structure meet the design requirements. It shows that this method and model introduced in this research have certain feasibility.
Originality/value
This study is the first attempt to apply the robust optimization model based on interval analysis to the optimization of EMU structure and obtain the optimal solution set that meets the design requirements. Therefore, this study provides an idea for nonprobabilistic robust optimization of the EMU structure.
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Saima Sajid, Norehan Abdullah and Abdul Razak Chik
The participation of females in economic activity remains a challenge, and received a lot of attention for a better labor policy discourse. The empirical research focused widely…
Abstract
Purpose
The participation of females in economic activity remains a challenge, and received a lot of attention for a better labor policy discourse. The empirical research focused widely on the relationship between female labor force participation (FLFP) and economic development, called the feminization U-shape hypothesis. However, the linear/nonlinear relationship has been questioned due to empirical and methodological anomalies. Hence, this study aims to extend the previous work by reexamining this relationship in Pakistan.
Design/methodology/approach
The annual data from 1980 to 2021, the unit root tests augmented Dickey–Fuller and Phillips and Perron, the conventional autoregressive distributed lag bound test approach by including the quadratic-term of GDP per capita and the novel Sasabuchi–Lind–Mehlum (SLM) U test (2010) used for empirical estimation.
Findings
The findings revealed the prospects of a long-run nonlinear association between FLFP and economic development in Pakistan. However, an inverse U-shape exists between the female labor force participation rate (FLFPR) and GDP per capita, predicting that FLFP may decline in the future.
Research limitations/implications
The traditional feminization U-shape hypothesis has little empirical support in the case of Pakistan. Therefore, the Government of Pakistan should enhance the enabling environment for females through the provision of better job opportunities, technical skills, on-the-job training and social security benefits during all phases of economic development.
Originality/value
The conventional approach of testing U-shape is insufficient. To the best of the authors’ knowledge, therefore, this study incorporated a wider data set in a time series that is less evident, an advanced methodology SLM U test (2010), to validate the feminization U-shape hypothesis in Pakistan for the first time.
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The environmental deterioration has become one of the most economically consequential and charged topics. Numerous scholars have examined the driving factors failing to consider…
Abstract
Purpose
The environmental deterioration has become one of the most economically consequential and charged topics. Numerous scholars have examined the driving factors failing to consider the structural breaks. This study aims to explore sustainability using the per capita ecological footprints (EF) as an indicator of environmental adversities and controlling the resources rent [(natural resources (NR)], labor capital (LC), urbanization (UR) and per capita economic growth [gross domestic product (GDP)] of China.
Design/methodology/approach
Through the analysis of the long- and short-run effects with an autoregressive distributed lag model (ARDL), structural break based on BP test and Granger causality test based on vector error correction model (VECM), empirical evidence is provided for the policies formulation of sustainable development.
Findings
The long-run equilibrium between the EF and GDP, NR, UR and LC is proved. In the long run, an environmental Kuznets curve (EKC) relationship existed, but China is still in the rising stage of the curve; there is a positive relationship between the EF and NR, indicating a resource curse; the UR is also unsustainable. The LC is the most favorable factor for sustainable development. In the short term, only the lagged GDP has an inhibitory effect on the EF. Besides, all explanatory variables are Granger causes of the EF.
Originality/value
A novel attempt is made to examine the long-term equilibrium and short-term dynamics under the prerequisites that the structural break points with its time and frequencies were examined by BP test and ARDL and VECM framework and the validity of the EKC hypothesis is tested.
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Abbas Ali Chandio, Yuansheng Jiang, Abdul Rehman and Abdul Rauf
The climate change effects on agricultural output in different regions of the world and have been debated in the literature of emerging economies. Recently, the agriculture sector…
Abstract
Purpose
The climate change effects on agricultural output in different regions of the world and have been debated in the literature of emerging economies. Recently, the agriculture sector has influenced globally through climate change and also hurts all sectors of economies. This study aims to examine and explore the impact of global climate change on agricultural output in China over the period of 1982-2014.
Design/methodology/approach
Different unit root tests including augmented Dickey–Fuller, Phillips–Perron and Kwiatkowski, Phillips, Schmidt and Shin are used to check the order of integration among the study variables. The autoregressive distributed lag (ARDL) bounds testing approach to cointegration and the Johansen cointegration test are applied to assess the association among the study variables with the evidence of long-run and short-run analysis.
Findings
Unit root test estimations confirm that all variables are stationary at the combination of I(0) and I(1). The results show that CO2 emissions have a significant effect on agricultural output in both long-run and short-run analyses, while temperature and rainfall have a negative effect on agricultural output in the long-run. Among other determinants, the land area under cereal crops, fertilizer consumption, and energy consumption have a positive and significant association with agricultural output in both long-run and short-run analysis. The estimated coefficient of the error correction term is also highly significant.
Research limitations/implications
China’s population is multiplying, and in the coming decades, the country will face food safety and security challenges. Possible initiatives are needed to configure the Chinese Government to cope with the adverse effects of climate change on agriculture and ensure adequate food for the growing population. In concise, the analysis specifies that legislators and policy experts should spot that the climate change would transmute the total output factors, accordingly a county or regional specific and crop-specific total factor of production pattern adaptation is indorsed.
Originality/value
The present empirical study is the first, to the best of the authors’ knowledge, to investigate the impact of global climate change on agricultural output in China by using ARDL bounds testing approach to cointegration and Johansen cointegration test.
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Tao Sun, Weizhong Li and Bo Dong
The purpose of this paper is to test the feasibility of lattice Boltzmann method (LBM) for numerical simulation of nucleate boiling and transition boiling. In addition, the…
Abstract
Purpose
The purpose of this paper is to test the feasibility of lattice Boltzmann method (LBM) for numerical simulation of nucleate boiling and transition boiling. In addition, the processes of nucleate and transition boiling on vertical wall are simulated. The heat transfer mechanism is discussed based on the evolution of temperature field.
Design/methodology/approach
In this paper, nucleate boiling and transition boiling are numerically investigated by LBM. A lattice Boltzmann (LB) multiphase model combining with a LB thermal model is used to predict the phase-change process.
Findings
Numerical results are in good agreement with existing experimental results. Numerical results confirm the feasibility of the hybrid LBM for direct simulations of nucleate and transition boiling. The data exhibit correct parametric dependencies of bubble departure diameter compared with experimental correlation and relevant references.
Research limitations/implications
All the simulations are performed in two-dimensions in this paper. In the future work, the boiling process will be simulated in three-dimensional.
Practical implications
This study demonstrated a potential model that can be applied to the investigation of phase change heat transfer, which is one of the effective techniques for enhance the heat transfer in engineering. The numerical results can be considered as a basic work or a reference for generalizing LB method in the practical application about nucleate boiling and transition boiling.
Originality/value
The hybrid LBM is first used for simulation of nucleate and transition boiling on vertical surface. Heat transfer mechanism during boiling is discussed based on the numerical results.
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Ri Liu, Xiuxia Sun and Wenhan Dong
During low altitude airdrop operations, the heavy cargo moving inside and the sudden dropping out exert serious threats on the aircraft safety and mission performance. This paper…
Abstract
Purpose
During low altitude airdrop operations, the heavy cargo moving inside and the sudden dropping out exert serious threats on the aircraft safety and mission performance. This paper aims to propose an efficient flight control method for the airdrop operations.
Design/methodology/approach
A novel controller which combines feedback linearization with nonlinear integral sliding mode control is proposed. The aircraft airdrop model is decoupled and linearized by using the feedback linearization technique. On this basis, an integral sliding mode controller is designed to stabilize the speed and pitch attitude of the aircraft. In the sliding manifold, one class of nonlinear functions with the property of “smaller errors correspond to bigger gains and bigger errors correspond to saturated gains” is introduced to form the integral term; thus, the overcompensation of the integral term to big errors is omitted, and the dynamic response performance is improved. Lyapunov-based stability analysis shows that the controller could completely reject model uncertainties by choosing proper controller parameters.
Findings
The flight control system with strong robustness could meet the low altitude airdrop indexes in the maximum weight cargo airdrop task.
Originality/value
This paper fulfils an urgent need to study how to control the aircraft to guarantee mission performance and flight safety during the low altitude airdrop operations.