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1 – 10 of over 2000Hui Quan, Yi Chai, Rennian Li, Guo-Yi Peng and Ying Guo
Having read previous literature about vortex pump, we noticed that mechanisms of circulating flow and its relationship with energy transition remain unclear yet. However, this…
Abstract
Purpose
Having read previous literature about vortex pump, we noticed that mechanisms of circulating flow and its relationship with energy transition remain unclear yet. However, this mechanism, which should be clarified, significantly influences the pump’s efficiency. To comply with the aim of investigating it, the 150WX-200-20 type pump is selected as study object in our present work.
Design/methodology/approach
Numerical simulation is conducted to formulate interactions between flow rate and geometric parameters of circulating flow with certain types of blade while experiments on inner flow are served as a witness to provide experimental confirmation of numerical results. Based on these, we coupled some parameters with the pump’s external performance to study their internal connections.
Findings
It is concluded that separatrix between circulating flow and other turbulent forms is not that clear under low flow rate. With flow increases, hydraulic losses coming of it will be dominant within the front chamber. Besides, we analogized circulating flow to vortices so as to make a quantitative analysis on its progressive evolution with changing flow, and vortices speaking for circulating flow can be divided into two groups. One is called main circulating flow vortex (hereinafter referred to as MCFV), which occurs all the time while subsidiary circulating flow vortices (hereinafter referred to as SCFV) appear in certain conditions. This context discusses the primary phase of our work with intent to follow up further with circulating flow characterized by vortices (hereinafter referred to as CFV). We confirmed that MCFV Vortex 1 (Vor1) directly influences the efficiency while SCFVs only play helping. As the flow goes to the given working condition, fluids in this pump tend to be steady with the size of CFVs getting larger and their shape being regular. Meanwhile, for MCFV Vor2 and Vor4, their geometric parameters are the key factors for efficiency. When CFVs become steady, they absorb other vortices nearby, as they have higher viscosity with the efficiency reaching its maximum.
Originality/value
The research results explore a new way to measure the circulating flow and help work out the causation of this flow pattern, which may be used to improve the vortex pump’s efficiency.
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Guo Yi, Junhua Xu and Chuanbo Zheng
There are obvious differences in corrosion resistance of different 2205 welding joints with different ratios of austenite and ferrite, from the top to the bottom, the austenite…
Abstract
Purpose
There are obvious differences in corrosion resistance of different 2205 welding joints with different ratios of austenite and ferrite, from the top to the bottom, the austenite content decreased gradually while the ferrite increased. In each region of welded joint, the pitting resistance number of ferrite is higher than that of austenite; pitting corrosion is more likely to occur in austenite phase first on the top region of the weld and in the secondary phase precipitates on the other regions of the weld. The fluctuation of the ratio of austenite and ferrite has a great influence on performance of passive film in 3.5 per cent NaCl solution.
Design/methodology/approach
To study the corrosion behavior of welded joint, the samples were obtained by laser hybrid welding. Pitting corrosion was studied in different area of welded joint. The Mott–Schottky curves of welded joints were measured to study the passive film on the different welded joint area.
Findings
Due to the difference of heat input and the limit of filler depth of the wire, the microstructure of duplex stainless steel laser welding joint has obvious difference in the thickness direction. In addition, there will be harmful secondary phase (such as chromium nitride and σphase) precipitates in the lower part of the joint. For the welded joint, the corrosion resistance decreases with the increase in the difference of the microstructure. Pitting corrosion usually takes the two phases as the nucleation point and grows up. The surface of 2205 duplex stainless steel laser hybrid welding joint cannot form a complete passive film in 3.5 per cent NaCl solution, and the more the ratios of austenite and ferrite deviate from equilibrium position (50:50), the worse the performance of passive film is.
Originality/value
In this paper, the authors attempt to establish the correlation between the semiconductor electronic properties of passive film and the difference of microstructures and the component in a joint welded by laser hybrid welding. The effect of passive film on the corrosion resistance of the weld was further investigated.
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Zhimei Yuan, Yi Guo and Xingdong Wang
The purpose of this paper is to examine the role of action visibility in moderating the relationship between firm response and individual legitimacy judgment. Since a firm may…
Abstract
Purpose
The purpose of this paper is to examine the role of action visibility in moderating the relationship between firm response and individual legitimacy judgment. Since a firm may decouple its public commitment from its actual practice to cope with conflicting stakeholder interests, visibility is important for consumers to make judgment because it is difficult for them to observe a firm’s actual fulfillment of its public commitment to quality assurance after a product-harm crisis.
Design/methodology/approach
Scenario-based mixed design experiments were employed and 718 valid responses were collected.
Findings
The results indicated that, while acknowledging responsibility produced more favorable legitimacy judgment than denial, decoupling produced no better judgment than denial. However, higher visibility significantly amplified the effect size. Specifically, under the condition of high visibility, not only did acknowledging responsibility produce much more favorable judgment than denial, but so did decoupling.
Research limitations/implications
This study provided empirical evidence that action visibility moderated the relationship between firm response and individual legitimacy judgment, thus complementing the literature on crisis management.
Practical implications
This study provided executives or managers with optimal, suboptimal and least optimal response strategies under different levels of action visibility.
Originality/value
Much of the extant research on response strategy for organizations to deal with product-harm crisis ignored the moderating role of action visibility. Past research on legitimacy judgment focused on organization. This paper combined firm response, action visibility and individual-level legitimacy judgment.
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Shiang-Wuu Perng, Horng Wen Wu, Nugroho Putra Kelana, Yi-Ling Guo and Chen-Jui Yang
The purpose of this paper, computational fluid dynamics (CFD) work, is to promote turbulent thermal convection in a heated circular tube using a passive scheme of a slotted…
Abstract
Purpose
The purpose of this paper, computational fluid dynamics (CFD) work, is to promote turbulent thermal convection in a heated circular tube using a passive scheme of a slotted twisted sheet.
Design/methodology/approach
The inventive design uses square-cut and conjugate triangular perforations to diversify the twisted tape for better thermal convection. The current novel passive scheme methodology is accomplished by carving the same square cuts and slitting various sizes of equilateral triangle perforations (side length varies between 8 and 16 mm). The re-normalisation group turbulence model and the semi-implicit method for pressure-linked equation method examine the turbulent thermal convection aspects of all simulations at different Reynolds numbers (6,000, 10,000 and 14,000).
Findings
The analyses of simulations exhibit that the placement of a twisted tape with triangle perforations and equidistant square cuts can effectually promote thermal convection in a circular tube. A larger-sized triangle perforation can increase the thermal convection enhancement and thermal performance factor, but an enlarged perforation may decrease the thermal convection enhancement and thermal performance factor. As a result, compared with the smooth circular tube, the circular tube with the slotted twisted sheet slit by a 10 mm equilateral triangle brings about the maximum improvement ratio of the mean Nusselt number of about 2.8 at Re = 6,000. Under weighing the friction through the circular tube, the tube with the slotted twisted sheet slit by a 10 mm equilateral triangle gains the best thermal performance factor of about 1.36 at Re = 6,000.
Research limitations/implications
The working fluid is water and its physical features are assumed to be constant. In addition, the fluid is considered a steady flow in this CFD work.
Practical implications
These CFD predictions will benefit the development of heat exchanger tubes equipped with a slotted twisted sheet to acquire preferable thermal convection enhancement.
Social implications
Higher thermal performance achieved by placing a slotted twisted tape in a heated tube will benefit society in lower energy consumption, machinery maintenance costs and impact on the environment.
Originality/value
This study combined triangle perforations and square cuts on the twisted sheet. This combination can induce the fluid flow across the sheet to disturb the swirling flow and then promote the fluid mixing to increase thermal convection. Therefore, this modified tape can be a profitable passive device for designing a heat exchanger.
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Guo Yi, Jianxu Mao, Yaonan Wang, Hui Zhang and Zhiqiang Miao
The purpose of this paper is to consider the leader-following formation control problem for nonholonomic vehicles based on a novel biologically inspired neurodynamics approach.
Abstract
Purpose
The purpose of this paper is to consider the leader-following formation control problem for nonholonomic vehicles based on a novel biologically inspired neurodynamics approach.
Design/methodology/approach
The interactions among the networked multi-vehicle system is modeled by an undirected graph. First, a distributed estimation law is proposed for each follower vehicle to estimate the state including the position, orientation and linear velocity of the leader. Then, a distributed formation tracking control law is designed based on the estimated state of the leader, where a bio-inspired neural dynamic is introduced to solve the impractical velocity jumps problem. Explicit stability and convergence analyses are presented using Lyapunov tools.
Findings
The effectiveness and efficiency of the proposed control law are demonstrated by numerical simulations and physical vehicle experiments. Consequently, the proposed protocol can successfully achieve the desired formation under connected topologies while tracking the trajectory generated by the leader.
Originality/value
This paper proposes a neurodynamics-based leader–follower formation tracking algorithm for multiple nonholonomic vehicles.
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Saleha Noor, Yi Guo, Syed Hamad Hassan Shah, Philippe Fournier-Viger and M. Saqib Nawaz
The novel Coronavirus (COVID-19) pandemic, which started in late December 2019, has spread to more than 200 countries. As no vaccine is yet available for this pandemic, government…
Abstract
Purpose
The novel Coronavirus (COVID-19) pandemic, which started in late December 2019, has spread to more than 200 countries. As no vaccine is yet available for this pandemic, government and health agencies are taking draconian steps to contain it. This pandemic is also trending on social media, particularly on Twitter. The purpose of this study is to explore and analyze the general public reactions to the COVID-19 outbreak on Twitter.
Design/methodology/approach
This study conducts a thematic analysis of COVID-19 tweets through VOSviewer to examine people’s reactions related to the COVID-19 outbreak in the world. Moreover, sequential pattern mining (SPM) techniques are used to find frequent words/patterns and their relationship in tweets.
Findings
Seven clusters (themes) were found through VOSviewer: Cluster 1 (green): public sentiments about COVID-19 in the USA. Cluster 2 (red): public sentiments about COVID-19 in Italy and Iran and a vaccine, Cluster 3 (purple): public sentiments about doomsday and science credibility. Cluster 4 (blue): public sentiments about COVID-19 in India. Cluster 5 (yellow): public sentiments about COVID-19’s emergence. Cluster 6 (light blue): public sentiments about COVID-19 in the Philippines. Cluster 7 (orange): Public sentiments about COVID-19 US Intelligence Report. The most frequent words/patterns discovered with SPM were “COVID-19,” “Coronavirus,” “Chinese virus” and the most frequent and high confidence sequential rules were related to “Coronavirus, testing, lockdown, China and Wuhan.”
Research limitations/implications
The methodology can be used to analyze the opinions/thoughts of the general public on Twitter and to categorize them accordingly. Moreover, the categories (generated by VOSviewer) can be correlated with the results obtained with pattern mining techniques.
Social implications
This study has a significant socio-economic impact as Twitter offers content posting and sharing to billions of users worldwide.
Originality/value
According to the authors’ best knowledge, this may be the first study to carry out a thematic analysis of COVID-19 tweets at a glance and mining the tweets with SPM to investigate how people reacted to the COVID-19 outbreak on Twitter.
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Keywords
Muhamad Husnain Mohd Noh, Mohd Akramin Mohd Romlay, Chuan Zun Liang, Mohd Shamil Shaari and Akiyuki Takahashi
Failure of the materials occurs once the stress intensity factor (SIF) overtakes the material fracture toughness. At this level, the crack will grow rapidly resulting in unstable…
Abstract
Purpose
Failure of the materials occurs once the stress intensity factor (SIF) overtakes the material fracture toughness. At this level, the crack will grow rapidly resulting in unstable crack growth until a complete fracture happens. The SIF calculation of the materials can be conducted by experimental, theoretical and numerical techniques. Prediction of SIF is crucial to ensure safety life from the material failure. The aim of the simulation study is to evaluate the accuracy of SIF prediction using finite element analysis.
Design/methodology/approach
The bootstrap resampling method is employed in S-version finite element model (S-FEM) to generate the random variables in this simulation analysis. The SIF analysis studies are promoted by bootstrap S-version Finite Element Model (BootstrapS-FEM). Virtual crack closure-integral method (VCCM) is an important concept to compute the energy release rate and SIF. The semielliptical crack shape is applied with different crack shape aspect ratio in this simulation analysis. The BootstrapS-FEM produces the prediction of SIFs for tension model.
Findings
The mean of BootstrapS-FEM is calculated from 100 samples by the resampling method. The bounds are computed based on the lower and upper bounds of the hundred samples of BootstrapS-FEM. The prediction of SIFs is validated with Newman–Raju solution and deterministic S-FEM within 95 percent confidence bounds. All possible values of SIF estimation by BootstrapS-FEM are plotted in a graph. The mean of the BootstrapS-FEM is referred to as point estimation. The Newman–Raju solution and deterministic S-FEM values are within the 95 percent confidence bounds. Thus, the BootstrapS-FEM is considered valid for the prediction with less than 6 percent of percentage error.
Originality/value
The bootstrap resampling method is employed in S-FEM to generate the random variables in this simulation analysis.
Details
Keywords
Hui-Wen Deng and Kwok Wah Cheung
The National People’s Congress (NPC) of People’s Republic of China, the highest organ of state power, is popularly seen as a rubber-stamp entity. However, it has been…
Abstract
Purpose
The National People’s Congress (NPC) of People’s Republic of China, the highest organ of state power, is popularly seen as a rubber-stamp entity. However, it has been substantially evolving its roles to accommodate the governance discourses within China’s political system over the decades. This study aims to explore the changes of governance discourse of the NPC within China’s political system through which to offer a thorough understanding of the NPC’s evolving substantial role in current China.
Design/methodology/approach
This study deploys a historical approach to explore the changes of governance discourse of the NPC that has seen a growing importance in China’s political agenda, as argued by this study.
Findings
The authors find that the NPC has been substantially evolving its role within China’s political system in which the Chinese Communist Party has created different governance discourses. Besides, the NPC and its Standing Committee have asserted its authority as a substantial actor within China’s political system. The NPC is no longer functioned as a rubber-stamp institution, though it is still popularized as a rubber stamp by many scholars.
Research limitations/implications
This study is a historical elaboration on the development of NPC under three governance discourses. It might be, to some extent, relatively descriptive in nature.
Originality/value
This study, therefore, sheds some light on a revisit on the governance discourses in current China.
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Keywords
Mian Wang and Yajing Feng
Special education in China has lagged behind regular education for many years, however, the past few decades, the government has made considerable efforts to develop and improve…
Abstract
Special education in China has lagged behind regular education for many years, however, the past few decades, the government has made considerable efforts to develop and improve the special education system. While the citizens of China have had a generic moral interest in disability since ancient times, the development of special education schools did not occur until American and European missionaries started schools for the visually and hearing impaired in the 19th century. The next major influence in the development of the special education system occurred with China’s Cultural Revolution in 1978. Interestingly, there is not any exclusive legislation on special education but in the 1980s, the government started Learning in Regular Classrooms (LRC), which is China’s version of inclusion. LRC has progressed rapidly the past two decades; however, the quality of instruction is low due to a lack of specialists, a shortage of personnel, inadequate funding, and limited technology as well as other barriers that are delineated in the chapter. The chapter emphasizes the government’s recent efforts in in-service teacher training, the preparation of preservice teachers, working with families, developing community rehabilitation training programs, and implementing evidence-based practices. Special education in China today is at a good place but it has quite a way from the ideal situation.
Considers TQM from a cultural perspective using the influence of Confucian work dynamism and Chinese cultural beliefs on Hong Kong companies. Asks if these cultural beliefs…
Abstract
Considers TQM from a cultural perspective using the influence of Confucian work dynamism and Chinese cultural beliefs on Hong Kong companies. Asks if these cultural beliefs conflict with modern quality management philosophy and presents the findings of research covering Chinese literature, experts in Chinese philosophy and Hong Kong TQM experts. Outlines research methods and concludes that there are relevant principles which can be used when implementing TQM.
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