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1 – 10 of 17Zhihao Wang, Wenliang Chen, Min Wang, Qinghe Xu and Can Huang
The purpose of this study is to improve the position and posture accuracy of posture alignment mechanism. The automatic drilling and riveting machine is an important equipment for…
Abstract
Purpose
The purpose of this study is to improve the position and posture accuracy of posture alignment mechanism. The automatic drilling and riveting machine is an important equipment for aircraft assembly. The alignment accuracy of position and posture of the bracket type posture alignment mechanism has a great influence on the operation effect of the machine. Therefore, it is necessary to carry out the kinematic calibration.
Design/methodology/approach
Based on analysis of elastic deformation of the bracket and geometric errors of the posture alignment mechanism, an improved method of kinematic calibration was proposed. The position and posture errors of bracket caused by geometric errors were separated from those caused by gravity. The method of reduction of dimensions was applied to deal with the error coefficient matrix in error identification, and it did not change the coefficient of the error terms. The target position and its posture were corrected to improve the error compensation accuracy. Furthermore, numerical simulation and experimental verification were carried out.
Findings
The simulation and experimental results show that considering the influence of the elastic deformation of the bracket on the calibration effect, the error identification accuracy and compensation accuracy can be improved. The maximum value of position error is reduced from 5.33 mm to 1.60 × 10−1 mm and the maximum value of posture error is reduced from 1.07 × 10−3 rad to 6.02 × 10−4 rad, which is superior to the accuracy without considering the gravity factor.
Originality/value
This paper presents a calibration method considering the effects of geometric errors and gravity. By separating position and posture errors caused by different factors and correcting the target position and its posture, the results of the calibration method are greatly improved. The proposed method might be applied to any parallel mechanism based on the positioner.
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Liping Ding, Shujie Tan, Wenliang Chen, Yaming Jin and Yicha Zhang
The manufacturability of extremely fine porous structures in the SLM process has rarely been investigated, leading to unpredicted manufacturing results and preventing steady…
Abstract
Purpose
The manufacturability of extremely fine porous structures in the SLM process has rarely been investigated, leading to unpredicted manufacturing results and preventing steady medical or industrial application. The research objective is to find out the process limitation and key processing parameters for printing fine porous structures so as to give reference for design and manufacturing planning.
Design/methodology/approach
In metallic AM processes, the difficulty of geometric modeling and manufacturing of structures with pore sizes less than 350 μm exists. The manufacturability of porous structures in selective laser melting (SLM) has rarely been investigated, leading to unpredicted manufacturing results and preventing steady medical or industrial application. To solve this problem, a comprehensive experimental study was conducted to benchmark the manufacturability of the SLM process for extremely fine porous structures (less than 350 um and near a limitation of 100 um) and propose a manufacturing result evaluation method. Numerous porous structure samples were printed to help collect critical datasets for manufacturability analysis.
Findings
The results show that the SLM process can achieve an extreme fine feature with a diameter of 90 μm in stable process control, and the process parameters with their control strategies as well as the printing process planning have an important impact on the printing results. A statistical analysis reveals the implicit complex relations between the porous structure geometries and the SLM process parameter settings.
Originality/value
It is the first time to investigate the manufacturability of extremely fine porous structures of SLM. The method for manufacturability analysis and printing parameter control of fine porous structure are discussed.
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Guowei Pan, Wenliang Chen and Hui Wang
The purpose of this paper is to use the redundancy of a new hybrid automatic fastening system (HAFS) for aircraft assembly in the best way.
Abstract
Purpose
The purpose of this paper is to use the redundancy of a new hybrid automatic fastening system (HAFS) for aircraft assembly in the best way.
Design/methodology/approach
First, the kinematic model of HAFS is divided into three sub-models, which are the upper/lower tool and parallel robot. With the geometric coordination relationship, a comprehensive kinematic model of the HAFS is built by mathematically assembling the sub-models based on the DH method. Then, a novel master-slave decoupling strategy for inverse kinematics solution is proposed. With the combination of the minimum energy consumption and the comfortable configuration, a multi-objective redundancy resolution method is developed to optimize the fastening configuration of the HAFS, which keep the HAFS away from the joint-limits and collision avoiding in the aircraft panel assembly process.
Findings
An efficient multi-objective posture optimization algorithm to use the redundancy in the best way is obtained. Simulation and an experiment are used to demonstrate the correctness of the proposed method. Moreover, the position and orientation errors of the drilling holes are within 0.222 mm and 0.356°, which are accurate enough for the automatic fastening in aircraft manufacturing.
Practical implications
This method has been used in the HAFS control system, and the practical results show the aircraft components can be fastened automatically through this method with high efficiency and high quality.
Originality/value
This paper proposes a comprehensive kinematic model and a novel decoupling strategy for inverse kinematic solution of the HAFS, which provides a reference to utilize the redundancy in the best way for a hybrid machine with redundant function.
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The paper aims to explore multilingual thesauri automation construction based on the freely available digital library resources. The key methods and study results are presented in…
Abstract
Purpose
The paper aims to explore multilingual thesauri automation construction based on the freely available digital library resources. The key methods and study results are presented in the paper. It also proposes a way that terms are automatically extracted from multilingual parallel corpus.
Design/methodology/approach
The study adopted the technology of natural language processing to analyze the linguistics characteristics of terms, and combined this with statistical analyses to extract the terms from technological documents. The methods consist of automatically extracting and filtering terms, judging and building relationship among terms, building the multilingual parallel corpus, and extracting term pairs between Chinese and foreign languages through calculating their associated probability. The experiments run on the Java test platform.
Findings
The study obtains the following conclusions: finding the similarities and differences between the Chinese thesaurus standard and international thesaurus standard. The methods for automatically extracting terms and building relationships among them are presented. Eventually the multilingual terms' translation sets are generated based on real corpora. The results of the study show that the proposed methods can obtain better performance. The effect of automatic terms' translation alignment method is better than that of traditional IBM model method.
Practical implications
The study results can provide references for further study and application of multilingual thesauri automation construction using Chinese as a pivot.
Originality/value
The paper proposes new ideas on thesaurus automation construction in the digital age. The presented method based on linguistics and statistics is a new attempt. According to the experimental results, this exploration and study is innovative and valuable. In addition, these ideas and methods give a good start for improving information services of the PRC's National Science and Technology Digital Library.
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Jianbo Zhu, Jialong Chen, Wenliang Jin and Qiming Li
Promoting technological innovation is important to address the complexity of major engineering challenges. Technological innovations include short-term innovations at the project…
Abstract
Purpose
Promoting technological innovation is important to address the complexity of major engineering challenges. Technological innovations include short-term innovations at the project level and long-term innovations that can enhance competitive advantages. The purpose of this study is to develop an incentive mechanism for the public sector that considers short-term and long-term efforts from the private sector, aiming to promote technological innovation in major engineering projects.
Design/methodology/approach
This study constructs an incentive model considering the differences in short-term and long-term innovation efforts from the private sector. This model emphasizes the spillover effect of long-term efforts on current projects and the cost synergy effect between short-term and long-term efforts. It also explores the factors influencing the optimal incentive strategies for the public sector and innovation strategies for the private sector.
Findings
The results indicate that increasing the output coefficient of short-term and long-term efforts and reducing the cost coefficient not only enhance the innovation efforts of the private sector but also prompt the public sector to increase the incentive coefficient. The spillover effect of long-term innovation efforts and the synergy effect of the two efforts are positively related to the incentive coefficient for the public sector.
Originality/value
This research addresses the existing gap in understanding how the public sector should devise incentive mechanisms for technological innovation when contractors acting as the private sector are responsible for construction within a public-private partnership (PPP) model. In constructing the incentive mechanism model, this study incorporates the private sector's short-term efforts at the project level and their long-term efforts for sustained corporate development, thus adding considerable practical significance.
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Wenliang Zhang, Heng Huang, Guogang Gao and Xiaopeng Xie
The purpose of this paper is to design the novel oil–air distributor (N-OAD). Its structure design, oil feeding reliability, service life and viscosity properties of air bubble…
Abstract
Purpose
The purpose of this paper is to design the novel oil–air distributor (N-OAD). Its structure design, oil feeding reliability, service life and viscosity properties of air bubble (AB) oil were analyzed. Meanwhile, the formation mechanism of AB oil was established based on Kelvin–Helmholtz instability.
Design/methodology/approach
First, oil–air distributor (OAD) and N-OAD were randomly selected for testing when the air pressure was 0.25 MPa and oil feeding was 100 times per hour. Then, the bubbles were found in the lubricant during the experiment, and the void fraction and viscosity properties of AB oil were tested by image processing method and the MARS 40 rheometer, respectively.
Findings
N-OAD has longer service life and higher working reliability than OAD. The key factors of AB oil formation were air pressure and oil feeding. And the void fraction of AB oil has different results on the viscosity at high and low shear rates.
Originality/value
The outcome of this research paper gives an insight to improve the reliability of oil–air lubrication systems and the safety factor of machine tool spindle operation.
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Wenliang Fan, Wei Shen, Qingbin Zhang and Alfredo H.-S. Ang
The purpose of this study is to improve the efficiency and accuracy of response surface method (RSM), as well as its robustness.
Abstract
Purpose
The purpose of this study is to improve the efficiency and accuracy of response surface method (RSM), as well as its robustness.
Design/methodology/approach
By introducing cut-high-dimensional representation model (HDMR), the delineation of cross terms and the constitution analysis of component function, a new adaptive RSM is presented for reliability calculation, where a sampling scheme is also proposed to help constructing response surface close to limit-state.
Findings
The proposed method has a more feasible process of evaluating undetermined coefficients of each component function than traditional RSM, and performs well in terms of balancing the efficiency and accuracy when compared to the traditional second-order polynomial RSM. Moreover, the proposed method is robust on the parameter in a wide range, indicating that it is able to obtain convergent result in a wide feasible domain of sample points.
Originality/value
This study constructed an adaptive bivariate cut-HDMR by introducing delineation of cross-terms and constitution of univariate component function; and a new sampling technique is proposed.
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Xin Chen and Yingxi Liu
In Chinese libraries, short video platforms have emerged as a channel for new media marketing. Thus, this study aims to explore libraries’ communication influence on China’s…
Abstract
Purpose
In Chinese libraries, short video platforms have emerged as a channel for new media marketing. Thus, this study aims to explore libraries’ communication influence on China’s largest short video platform, that is, Douyin (the Chinese version of Tiktok), and to provide corresponding suggestions for improvement of libraries’ communication influence in the short video platform.
Design/methodology/approach
Based on the Douyin Communication Index (DCI), this paper collects the top 200 library Douyin accounts of cultural reading in China and uses statistical and content analyses to evaluate the communication influence of library Douyin accounts.
Findings
Study findings show that libraries of various types and in various regions currently have an unbalanced development trend, with public libraries accounting for the vast majority and nearly half of the libraries located in China’s eastern region. Analysis of variance shows differences in the influence of Douyin communication among library types. Correlation analysis shows that indicators with a high correlation with DCI include the number of new works, likes, shares, and comments. In marketing content, the library’s high-impact short videos have characteristics of value, interest, and emotional touch.
Originality/value
This study uses a hybrid research method to explore Chinese libraries’ communication influence using the Douyin short video platform. Compared to other parts of the world, short videos in Chinese libraries have unique characteristics. They are rooted in China’s history and reality, showcasing the unique charm of Chinese library culture and serving as a unique reference for library marketing activities around the world.
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Yanbing Ni, Yizhang Cui, Shilei Jia, Chenghao Lu and Wenliang Lu
The purpose of this paper is to propose a method for selecting the position and attitude trajectory of error measurement to improve the kinematic calibration efficiency of a one…
Abstract
Purpose
The purpose of this paper is to propose a method for selecting the position and attitude trajectory of error measurement to improve the kinematic calibration efficiency of a one translational and two rotational (1T2R) parallel power head and to improve the error compensation effect by improving the properties of the error identification matrix.
Design/methodology/approach
First, a general mapping model between the endpoint synthesis error is established and each geometric error source. Second, a model for optimizing the position and attitude trajectory of error measurement based on sensitivity analysis results is proposed, providing a basis for optimizing the error measurement trajectory of the mechanism in the working space. Finally, distance error measurement information and principal component analysis (PCA) ideas are used to construct an error identification matrix. The robustness and compensation effect of the identification algorithm were verified by simulation and through experiments.
Findings
Through sensitivity analysis, it is found that the distribution of the sensitivity coefficient of each error source in the plane of the workspace can approximately represent its distribution in the workspace, and when the end of the mechanism moves in a circle with a large nutation angle, the comprehensive influence coefficient of each sensitivity is the largest. Residual analysis shows that the robustness of the identification algorithm with the idea of PCA is improved. Through experiments, it is found that the compensation effect is improved.
Originality/value
A model for optimizing the position and attitude trajectory of error measurement is proposed, which can effectively improve the error measurement efficiency of the 1T2R parallel mechanism. In addition, the PCA idea is introduced. A least-squares PCA error identification algorithm that improves the robustness of the identification algorithm by improving the property of the identification matrix is proposed, and the compensation effect is improved. This method has been verified by experiments on 1T2R parallel mechanism and can be extended to other similar parallel mechanisms.
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Despite a ravaging pandemic worldwide, Vietnam managed to contain the local outbreak, partly owing to its carefully implemented risk communications campaign. This chapter…
Abstract
Despite a ravaging pandemic worldwide, Vietnam managed to contain the local outbreak, partly owing to its carefully implemented risk communications campaign. This chapter investigated the effectiveness of official Vietnam government communications, the sentiment of foreign media reporting on Vietnam, and any challenges. Content analysis was applied to samples from government communications (43 samples); international articles (46); and social media conversations (33). Official government communications were quite accurate, timely, and effective in displaying transparency, employing war symbolism, and shared responsibility, but should more clearly separate between state and expert, offer differing views, and highlight the benefits of compliance. International articles praised the government's viral PSA TikTok video, its transparency, and the netizens' nationalist narratives. While some evidence was found for infodemic, blaming, and heroization, the sample was too small to be conclusive. Future studies should expand the timeframe to a longer duration, quantitatively appraise a wider sampling of social media conversations, and possibly conduct primary interviews with experts, policy makers, and the public.
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