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1 – 10 of 35Zunhui Zhao, Haibin Shang, Pingyuan Cui and Xiangyu Huang
The purpose of this paper is to present a solution space searching method to study the initial design of interplanetary low thrust gravity assist trajectory.
Abstract
Purpose
The purpose of this paper is to present a solution space searching method to study the initial design of interplanetary low thrust gravity assist trajectory.
Design/methodology/approach
For reducing the complexity and nonlinearity of the initial design problem, a sixth degree inverse polynomial shape based approach is brought. Then some improvements are provided for solving the parameters in the shape function and a quasi‐lambert solver is brought through the shape based method, the thrust profile can be generated under the given time of flight, boundary states including positions and velocities for low thrust phase. Combining gravity assist model, the problem is summarized and an improved pruning technique is used for searching the feasible solution space for low thrust gravity assist trajectory.
Findings
Using the solution space searching method, the feasible solution region would be generated under the given mission condition. The treatment about gravity assist demonstrates more accurate than previous method. Also another advantage is that the searching method can be used to design different types of mission trajectory, including flyby and rendezvous trajectories.
Practical implications
The method can be used as an efficient approach to search the feasible region for the complex low thrust gravity assist trajectory, and it can provide appropriate initial guesses for the low thrust gravity assist trajectory in mission design phase.
Originality/value
Feasible solution space would be obtained through the searching method. The quasi‐Lambert solver in the paper is found under the shape‐based method and relative improvement, and it shows its availability during the searching process. Through mission trajectory design, the effectiveness of the method is shown.
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Gongwen Tang, Tingting Ren, Yi Wang, Zhishan Yan, Linrong Ma, Xiangyu Hou and Xin Huang
The purpose of this paper is to study the effect of the nano tube fillers on the corrosion protection properties of the self-curing epoxy (SEP) coatings.
Abstract
Purpose
The purpose of this paper is to study the effect of the nano tube fillers on the corrosion protection properties of the self-curing epoxy (SEP) coatings.
Design/methodology/approach
The self-curing epoxy (SEP) resin was synthesized via a reaction between diisopropoxy-bis ethylacetoacetato titanate and the epoxy resin. Halloysite nanotubes (HNTs) was surface modified by grafting (3-glycidoxypropyl) trimethoxysilane to obtain modified HNTs (mHNTs). The HNTs and mHNTs are used as nano tube fillers for the SEP coating. The thermal stability of the coatings was assessed via thermo-gravimetric analysis. The field-emission scanning electron microscopy (SEM) was conducted to analyze the surfaces and cross sections of the coatings. The anticorrosive efficiencies of the coatings were investigated by electrochemical measurements and a neutral salt spray test.
Findings
The results demonstrated that the additions of HNTs and mHNTs have little effect on the thermal degradation temperature of the SEP coating. However, the addition of the nanotubes reduced the corrosion resistance of the SEP coating.
Originality/value
The SEP coating itself showed excellent corrosion resistance without any reinforcement particles and is hence promising for application in the heavy-duty anticorrosion field of heat exchangers.
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Peng Wang, Lihong Dong, Haidou Wang, Guolu Li, Yuelan Di, Xiangyu Xie and Dong Huang
The skin and skeleton of aircraft are connected by adhesives or rivets to bear and transfer aerodynamic load. It is easy for crack and fracture damage to occur under the action of…
Abstract
Purpose
The skin and skeleton of aircraft are connected by adhesives or rivets to bear and transfer aerodynamic load. It is easy for crack and fracture damage to occur under the action of cyclic load, thus reducing aircraft bearing capacity/integrity and causing serious security risks. Therefore, it is particularly important that passive wireless radio frequency identification (RFID) sensors be used for the health monitoring of aircraft skin in its whole life cycle. This paper aims to investigate the influence of miniaturization on the coupling effect between RFID tag sensors.
Design/methodology/approach
Two groups of crack sensing systems based on RFID tags were designed. Gain and mutual impedance of sensor tags were analyzed via mode analysis. The reliability of crack detection of both sensing systems was compared using a preset experimental scheme.
Findings
Miniaturized antennas can reduce edge influence and the coupling effect. Gain and mutual impedance decrease with the increase in distance between dual tags. Backscatter power shows a decreasing trend and threshold power to activate tags in reader antenna increases. Results show that the miniaturization of size is more suitable for the application of multiple sensors.
Originality/value
By comparing two groups of sensing systems, the consistency of crack detection sensitivity is better when small tags are placed in parallel, which provides a theoretical basis for the application of small, passive and densely distributed crack sensors in the future.
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Xiangou Zhang, Yuexing Wang, Xiangyu Sun, Zejia Deng, Yingdong Pu, Ping Zhang, Zhiyong Huang and Quanfeng Zhou
Au stud bump bonding technology is an effective means to realize heterogeneous integration of commercial chips in the 2.5D electronic packaging. The purpose of this paper is to…
Abstract
Purpose
Au stud bump bonding technology is an effective means to realize heterogeneous integration of commercial chips in the 2.5D electronic packaging. The purpose of this paper is to study the long-term reliability of the Au stud bump treated by four different high temperature storage times (200°C for 0, 100, 200 and 300 h).
Design/methodology/approach
The bonding strength and the fracture behavior are investigated by chip shear test. The experiment is further studied by microstructural characterization approaches such as scanning electron microscope, energy dispersive spectrometer and so on.
Findings
It is recognized that there were mainly three typical fracture models during the chip shear test among all the Au stud bump samples treated by high temperature storage. For solder bump before aging, the fracture occurred at the interface between the Cu pad and the Au stud bump. As the aging time increased, the fracture mainly occurred inside the Au stud bump at 200°C for 100 and 200 h. When aging time increased to 300 h, it is found that the fracture transferred to the interface between the Au stud bump and the Al Pad.
Originality/value
In addition, the bonding strength also changed with the high temperature storage time increasing. The bonding strength does not change linearly with the high temperature storage time increasing but decreases first and then increases. The investigation shows that the formation of the intermetallic compounds because of the reaction between the Au and Al atoms plays a key role on the bonding strength and fracture behavior variation.
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Eli Gimmon, Ying Teng and Xiaobin He
This study aims to present multi-layered embeddedness and explore the main and interaction effects of political embeddedness on the performance of private enterprises in China…
Abstract
Purpose
This study aims to present multi-layered embeddedness and explore the main and interaction effects of political embeddedness on the performance of private enterprises in China. This study tests multi-layered embeddedness through interaction effects between three layers, namely, political, territorial and inter-firm embeddedness. Political embeddedness is related at the personal and the firm levels.
Design/methodology/approach
The authors used secondary data of four non-panel waves (2002, 2008, 2010 and 2016) of large samples having identical questions based on the Chinese private enterprises’ survey. The accumulated number of business owners’ responses is a total of 10,686.
Findings
The main effects of each of the layers of embeddedness showed a positive influence on enterprise performance consistently and unchanged over time which fits the Chinese Guanxi regardless of the immense macro-economic transition. However, unexpectedly some interactions showed negative significant effects on performance.
Practical implications
First, business owners should be aware of the specific contribution to the performance of political embeddedness at both the firm level and the personal level. Second, the pursuit of exercising simultaneously several layers of embeddedness may be detrimental to company performance. This study provides generalizable lessons regarding different embeddedness layers beyond the context of China’s transition economy.
Originality/value
First, the authors extend political embeddedness to the firm level whilst in previous research this construct had been mostly related to the personal level. Second, building on the resource-based view and redundant resources the authors present the disadvantage of “over-embeddedness” as related to multi-layered embeddedness which has been understudied.
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Shuyuan Xu, Jun Wang, Xiangyu Wang, Wenchi Shou and Tuan Ngo
This paper covers the development of a novel defect model for concrete highway bridges. The proposed defect model is intended to facilitate the identification of bridge’s…
Abstract
Purpose
This paper covers the development of a novel defect model for concrete highway bridges. The proposed defect model is intended to facilitate the identification of bridge’s condition information (i.e. defects), improve the efficiency and accuracy of bridge inspections by supporting practitioners and even machines with digitalised expert knowledge, and ultimately automate the process.
Design/methodology/approach
The research design consists of three major phases so as to (1) categorise common defect with regard to physical entities (i.e. bridge element), (2) establish internal relationships among those defects and (3) relate defects to their properties and potential causes. A mixed-method research approach, which includes a comprehensive literature review, focus groups and case studies, was employed to develop and validate the proposed defect model.
Findings
The data collected through the literature and focus groups were analysed and knowledge were extracted to form the novel defect model. The defect model was then validated and further calibrated through case study. Inspection reports of nearly 300 bridges in China were collected and analysed. The study uncovered the relationships between defects and a variety of inspection-related elements and represented in the form of an accessible, digitalised and user-friendly knowledge model.
Originality/value
The contribution of this paper is the development of a defect model that can assist inexperienced practitioners and even machines in the near future to conduct inspection tasks. For one, the proposed defect model can standardise the data collection process of bridge inspection, including the identification of defects and documentation of their vital properties, paving the path for the automation in subsequent stages (e.g. condition evaluation). For another, by retrieving rich experience and expert knowledge which have long been reserved and inherited in the industrial sector, the inspection efficiency and accuracy can be considerably improved.
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Xiangyu Liu, Chunyan Zhang, Cong Ni and Chenhui Lu
The purpose of this paper is to put forward a nvew reconfigurable multi-mode walking-rolling robot based on the single-loop closed-chain four-bar mechanism, and the robot can be…
Abstract
Purpose
The purpose of this paper is to put forward a nvew reconfigurable multi-mode walking-rolling robot based on the single-loop closed-chain four-bar mechanism, and the robot can be changed to different modes according to the terrain.
Design/methodology/approach
Based on the topological analysis, singularity analysis, feasibility analysis, gait analysis and the motion strategy based on motor time-sharing control, the paper theoretically verified that the robot can switch between the four motion modes.
Findings
The robot integrates four-bar walking, self-deforming and four-bar and six-bar rolling modes. A series of simulation and prototype experiment results are presented to verify the feasibility of multiple motion modes of the robot.
Originality/value
The work presented in this paper provides a good theoretical basis for further exploration of multiple mode mobile robots. It is an attempt to design the multi-mode mobile robot based on single loop kinematotropic mechanisms. It is also a kind of exploration of the new unknown movement law.
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David Huntsman, Alex Greer, Haley Murphy and Xiangyu (Dale) Li
While uncertainty during emergency response operations necessitates adaptive performance, emergency response organizations, such as the fire service, tend to constrain adaptive…
Abstract
Purpose
While uncertainty during emergency response operations necessitates adaptive performance, emergency response organizations, such as the fire service, tend to constrain adaptive behaviors due to their highly formalized bureaucratic structures. Structural theories suggest that leaders can empower employees to bypass these constraints.
Design/methodology/approach
Using survey data from four US fire departments, this research tests whether mid-level supervisors can empower firefighters by increasing their ability to improvise during complex emergency response operations, and whether this enhances department adaptive performance. Moderated mediation is also performed to assess whether senior leaders must also be effective, empowering leaders in order to achieve heightened levels of empowerment and subsequent adaptive performance, as many senior leaders in the fire service are criticized for being overly bureaucratic, risk averse, and resistant to change.
Findings
The findings support compensatory effects and show how immediate supervisors are key to overcoming senior leader deficiencies and producing adaptive performance during conditions of high uncertainty and complexity.
Originality/value
The lack of response organizations’ success during complex incidents is often attributed to senior leaders who are risk averse, overly bureaucratic, and resistant to change (Wankhade and Patnaik, 2020). This study is the first to show how empowering leadership can help overcome these constraints to enhance adaptive performance under complex conditions in the fire service.
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Chengtao Cai, Bing Fan, Xiangyu Weng, Qidan Zhu and Li Su
Because of their large field of view, omnistereo vision systems have been widely used as primary vision sensors in autonomous mobile robot tasks. The purpose of this article is to…
Abstract
Purpose
Because of their large field of view, omnistereo vision systems have been widely used as primary vision sensors in autonomous mobile robot tasks. The purpose of this article is to achieve real-time and accurate tracking by the omnidirectional vision robot system.
Design/methodology/approach
The authors provide in this study the key techniques required to obtain an accurate omnistereo target tracking and location robot system, including stereo rectification and target tracking in complex environment. A simple rectification model is proposed, and a local image processing method is used to reduce the computation time in the localization process. A target tracking method is improved to make it suitable for omnidirectional vision system. Using the proposed methods and some existing methods, an omnistereo target tracking and location system is established.
Findings
The experiments are conducted with all the necessary stages involved in obtaining a high-performance omnistereo vision system. The proposed correction algorithm can process the image in real time. The experimental results of the improved tracking algorithm are better than the original algorithm. The statistical analysis of the experimental results demonstrates the effectiveness of the system.
Originality/value
A simple rectification model is proposed, and a local image processing method is used to reduce the computation time in the localization process. A target tracking method is improved to make it suitable for omnidirectional vision system. Using the proposed methods and some existing methods, an omnistereo target tracking and location system is established.
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Yun Teng, Boyuan Pang and Xiangyu Guo
The authors are committed to providing the Chinese government with a foundation for making decisions that will protect black land and ensure long-term agricultural development.
Abstract
Purpose
The authors are committed to providing the Chinese government with a foundation for making decisions that will protect black land and ensure long-term agricultural development.
Design/methodology/approach
Using the grounded theory approach, this study investigates the influencing factors affecting the quality of black land in Northeast China and proposes a hypothetical model for the mechanism of the influencing factors on the quality of black land in Northeast China.
Findings
The factors influencing the quality of black land include not only soil quality, ecological quality and environmental quality, but also economic quality and management quality, and can be classified into five categories. There are complex influence relationships between various factors and black land quality, with soil quality, ecological quality, environmental quality and management quality having a positive influence on economic quality. Soil quality, ecological quality and environmental quality are all improved as a result of good management. Black land quality is influenced positively by environmental quality, economic quality and management quality.
Research limitations/implications
The quality of black land is a major concern in terms of food production and long-term agricultural development. The black land in Northeast China was chosen as the subject of this study, and the research findings have some limitations. The next step will be to expand from studying the black land in Northeast China to the black land worldwide.
Originality/value
In Northeast China, the quality of the five dimensions of black land must be improved in a coordinated and consistent manner.
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