Search results

1 – 10 of 485
To view the access options for this content please click here
Article
Publication date: 2 January 2018

Guohua Jiang, Dongmei Zhao and Bo Zhao

The purpose of this paper is to investigate the optoelectronic properties of the multichannel ZnO UV photodetectors.

Abstract

Purpose

The purpose of this paper is to investigate the optoelectronic properties of the multichannel ZnO UV photodetectors.

Design/methodology/approach

ZnO nanowires were assembled by dielectrophoresis for the UV photodetectors. Different ZnO channels were adjusted by different alternating current voltages and investigated for UV optoelectronic properties.

Findings

The number of the ZnO channels increases with the enhancing alternating current voltage. Optimum performance of the UV photodetectors is obtained with more channels.

Originality/value

Dielectrophoresis is a promising method for controllable assembly of multichannel ZnO photodetectors. ZnO photodetectors with more channels demonstrate a good response to 380-nm UV light, which shows great potential application in UV photodetector.

Details

Microelectronics International, vol. 35 no. 1
Type: Research Article
ISSN: 1356-5362

Keywords

To view the access options for this content please click here
Article
Publication date: 5 October 2018

Feiyan Guo, Fang Zou, Jian Hua Liu, Bo Zhao and Zhongqi Wang

Coordination feature (CF) is the information carrier in dimension and shape transfer process in aircraft manufacturing. The change of its geometric size, shape, position…

Abstract

Purpose

Coordination feature (CF) is the information carrier in dimension and shape transfer process in aircraft manufacturing. The change of its geometric size, shape, position or other attributes would affect the consistency of accumulated errors between two or more assemblies. To identify these “key characteristics” that have a close relationship with the assembly precision, a comprehensive method was developed under digital manufacturing environment, which was based on importance calculation. The multi-hierarchy and multi-station assembly process of aircraft products were also taken into consideration.

Design/methodology/approach

First, the interaction and evaluation relationship between components at different manufacturing stages was decomposed with a hierarchical net. Second, to meet coordination accuracy requirements, with the integrated application of Taguchi quality loss function, accuracy principal and error correction coefficient H, the quality loss between target features and candidate features at adjacent assembly hierarchies were calculated, which was based on their precision variation. Third, the influence degree and affected degree of the features were calculated with DEMATEL (decision-making trial and evaluation laboratory) method, and the concepts of centrality degree index and cause degree index were proposed for calculating the complete importance degree to eventually identify the CFs.

Findings

Based on the proposed methodology, CFs, affecting the skin profile and the flush coordination accuracy, were successfully identified at different assembly hierarchies to a certain type of wing flap component.

Originality/value

Benefit results for the engineering application showed that the deviation of skin profile was more accurate than before, and the tolerance was also closer to the centerline of required assembly precision range. Moreover, the stability in the assembly process was increased by 26.9 per cent, which could bring a higher assembly quality and an enhancement on aircraft’s flight performance.

Details

Assembly Automation, vol. 38 no. 4
Type: Research Article
ISSN: 0144-5154

Keywords

To view the access options for this content please click here
Article
Publication date: 13 November 2009

Bo Zhao and Hongjie Hu

The purpose of this paper is to develop a new inverse controller for servo‐system position tracking control based on neural network (NN) and model reference adaptive…

Abstract

Purpose

The purpose of this paper is to develop a new inverse controller for servo‐system position tracking control based on neural network (NN) and model reference adaptive control (MRAC).

Design/methodology/approach

First, the model of general servo‐systems is analyzed. Then, a MRAC based on neural network control (NNC) is proposed with mathematical prove of stability. In addition, several simulation cases and experiments are listed to verify the usability of the control scheme.

Findings

This scheme consists of an MRAC, an online NN controller and a robust controller in velocity‐loop. For reducing influence which arose from modeling error, unknown model dynamics, parameter variation, and load changes, the NN controller is introduced to counteract the various influence mentioned above dynamically. MRAC, NNC, and robust controller adjust system to track the approximate velocity‐loop reference model. In this way, the position‐loop is not sensitive to the disturbance on velocity‐loop, and the whole velocity‐loop can be treated as a simple linear model when designing the other parts of the system. In addition, a novel inverse control method based on linear velocity signal filter is introduced to this scheme. In this case, the MRAC, NNC, and robust controller perform as an adaptive inverse controller, which keeps the velocity signal tracking the position loop controller output.

Originality/value

The paper presents a new inverse controller with NNC and MRAC which is practical and flexible.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 28 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

To view the access options for this content please click here
Article
Publication date: 5 September 2017

Peter Lok

The purpose of this paper is to explore how a neo-liberal nationalist discourse of China imagines the spatial identity of the post-1997 Hong Kong with reference to Lost in

Abstract

Purpose

The purpose of this paper is to explore how a neo-liberal nationalist discourse of China imagines the spatial identity of the post-1997 Hong Kong with reference to Lost in Hong Kong, a new Chinese middle-class film in 2015 with successful box office sales.

Design/methodology/approach

Textual analysis with the aid of psychoanalysis, postcolonial studies and semiotics is used to interpret the meaning of the film in this study. The study also utilizes the previous literature reviews about the formation of the Chinese national identity to help analyze the distinct identity of the Chinese middle class today.

Findings

The discussion pinpoints how the new Chinese middle class as neo-liberal nationalists take Hong Kong as a “bizarre national redemptive space”. While Hong Kong is cinematically constructed as such a national other, this paper argues that the Hong Kong in question stands not for itself but in a form of “reverse hallucination” for pacifying the new Chinese middle class’ trauma under the rapid neo-liberalization of China in the 1990s.

Originality/value

This paper shows the new of formation of the Chinese nationalist’s discourse, especially the new Chinese middle-class discourse on Hong Kong after 1997.

Details

Social Transformations in Chinese Societies, vol. 13 no. 2
Type: Research Article
ISSN: 1871-2673

Keywords

To view the access options for this content please click here
Article
Publication date: 4 November 2014

Xin Wang, Wei Bing Hu and Zhao Bo Meng

The purpose of this paper is to establish the damage alarming indexes for ancient wood structures and study the damage sensitivity and noise robustness of these indexes…

Abstract

Purpose

The purpose of this paper is to establish the damage alarming indexes for ancient wood structures and study the damage sensitivity and noise robustness of these indexes under random excitation.

Design/methodology/approach

Xi’an Bell Tower is taken as a case in this paper to simulate the damage of ancient wood structures through finite element (FE) simulation and determine the satisfactory damage alarming indexes with wavelet packet energy spectrum.

Findings

The results of this paper show that: 1) the damage alarming indexes can effectively identify the damage of ancient wood structures, each index with a different damage sensitivity; 2) the energy ratio deviation is greater than the energy ratio variance and is close to the maximum variation of energy ratio; 3) the energy ratio deviation has a better alarming effect than the energy ratio variance during the initial period of the damage. With the accumulation of the damage, the energy ratio variance outperforms the energy ratio deviation; 4) the sensitivity of the energy ratio deviation and variance varies from positions, changing from the highest to lowest at the mortise-and-tenon joints, the beam mid-span and the plinth; 5) if signal to noise ratio (SNR) is 40db or larger, the indexes can accurately identify the damage of ancient wood structures. As SNR increases, the indexes will have an increasingly higher sensitivity and certain ability to resist noise.

Research limitations/implications

The FE model is simpiy, it does not completely reflect Xi’an Bell Tower.

Practical implications

It will provide a theoretical basis for the damage alarming of Xi’an Bell Tower.

Social implications

It makes structural health monitoring through structural vibration response under ambient excitation a new research field in damage detection as well as a positive way of ancient architecture protection.

Originality/value

This paper studies the damage alarming effect on ancient wood structures from different wavelet functions and wavelet packet decomposition levels. To study the effect under white noise environment, this paper adds Gaussian white noise with a SNR of 10, 20, 30, 40 and 50 db to the acceleration response signal of intact structure and damaged structure.

Details

Multidiscipline Modeling in Materials and Structures, vol. 10 no. 4
Type: Research Article
ISSN: 1573-6105

Keywords

To view the access options for this content please click here
Article
Publication date: 11 November 2013

Bo Zhao

The polymer air-drawing model of spunbonding nonwovens has been established. The influence of the density and the specific heat capacity of polymer melt at constant…

Abstract

Purpose

The polymer air-drawing model of spunbonding nonwovens has been established. The influence of the density and the specific heat capacity of polymer melt at constant pressure changing with polymer temperature on the fiber diameter have also been studied. The paper aims to discuss these issues.

Design/methodology/approach

TDMA method is used to solve the difference equations.

Findings

It can be concluded that a lower polymer throughput rate, a higher polymer melt initial temperature, a higher air initial temperature, and a higher air initial velocity can all produce finer fibers.

Originality/value

The results also reveal the great potential for this research in the computer-assisted design of spunbonding technology.

Details

International Journal of Clothing Science and Technology, vol. 25 no. 6
Type: Research Article
ISSN: 0955-6222

Keywords

To view the access options for this content please click here
Article
Publication date: 11 November 2013

Bo Zhao

– The purpose of this paper is to attempt to predict the fiber diameter of melt blowing nonwovens by means of physics model.

Abstract

Purpose

The purpose of this paper is to attempt to predict the fiber diameter of melt blowing nonwovens by means of physics model.

Design/methodology/approach

The effects of the processing parameters on the fiber diameter is studied using the established physics model.

Findings

The results show that the predicted and experimental values agree well, the physics model produces more accurate and stable predictions, which also indicates that the physics model is really an effective and available modeling method for predictors.

Originality/value

The results show the great potential of this research for computer assisted design of the melt blowing technology.

Details

International Journal of Clothing Science and Technology, vol. 25 no. 6
Type: Research Article
ISSN: 0955-6222

Keywords

To view the access options for this content please click here
Article
Publication date: 20 April 2015

Bo Zhao

The purpose of this paper is to establish three modeling methods (physical model, statistical model, and artificial neural network (ANN) model) and use it to predict the…

Abstract

Purpose

The purpose of this paper is to establish three modeling methods (physical model, statistical model, and artificial neural network (ANN) model) and use it to predict the fiber diameter of spunbonding nonwovens from the process parameters.

Design/methodology/approach

The results show the physical model is based on the inherent physical principles, it can yield reasonably good prediction results and provide insight into the relationship between process parameters and fiber diameter.

Findings

By analyzing the results of the physical model, the effects of process parameters on fiber diameter can be predicted. The ANN model has good approximation capability and fast convergence rate, it can provide quantitative predictions of fiber diameter and yield more accurate and stable predictions than the statistical model.

Originality/value

The effects of process parameters on fiber diameter are also determined by the ANN model. Excellent agreement is obtained between these two modeling methods.

Details

International Journal of Clothing Science and Technology, vol. 27 no. 2
Type: Research Article
ISSN: 0955-6222

Keywords

To view the access options for this content please click here
Article
Publication date: 27 May 2014

Bo Zhao

The air drawing model plays an important in spunbonding. The purpose of this paper is to study the influence of the density and the specific heat capacity of polymer melt…

Abstract

Purpose

The air drawing model plays an important in spunbonding. The purpose of this paper is to study the influence of the density and the specific heat capacity of polymer melt at constant pressure changing with polymer temperature on the fiber diameter.

Design/methodology/approach

The air drawing model of the polypropylene polymer in a spunbonding process is presented and solved by introducing the numerical computation results of the air flow field of aerodynamic device.

Findings

The model prediction of the filament fiber diameter coincides well with the experimental data. The effects of the processing parameters on the filament fiber diameter are discussed. A lower polymer throughput rate, higher polymer melt temperature, higher primary air temperature, higher venturi gap, higher air suction speed, and higher quench pressure can all produce finer filament fiber.

Originality/value

The experimental results show that the agreement between the results and experimental data are very better, which verifies the reliability of these models. The results show great prospects for this research in the field of computer assisted design of spunbonding technology.

Details

International Journal of Clothing Science and Technology, vol. 26 no. 2
Type: Research Article
ISSN: 0955-6222

Keywords

To view the access options for this content please click here
Article
Publication date: 2 March 2015

Bo Zhao

The purpose of this paper is to varify, the air drawing model and the air jet flow field model of dual slot shape die for a polymer in a melt blowing process were…

Abstract

Purpose

The purpose of this paper is to varify, the air drawing model and the air jet flow field model of dual slot shape die for a polymer in a melt blowing process were established, by the experimental results obtained with experimental equipment.

Design/methodology/approach

The air jet flow field model is solved by introducing the finite difference method. The air drawing model of polymers in the melt blowing process was studied with the help of the simulation results of the air jet flow field.

Findings

The higher air initial velocity and air initial temperature can all yield finer fibers and causes the fibers to be attenuated to a greater extent.

Originality/value

The predicted fiber diameter agrees well with the experimental result, which verifies the reliability of these models. At the same time, the results also reveal the great potential of this research for the computer-assisted design of melt blowing technology.

Details

International Journal of Clothing Science and Technology, vol. 27 no. 1
Type: Research Article
ISSN: 0955-6222

Keywords

1 – 10 of 485