Search results
1 – 10 of 30Jian Zhou and Jianli Liu
Visual quality control on raw textile fabrics is a vital process in weaving factories to ensure their exterior quality (visual defects or imperfection) satisfying customer…
Abstract
Purpose
Visual quality control on raw textile fabrics is a vital process in weaving factories to ensure their exterior quality (visual defects or imperfection) satisfying customer requirements. Commonly, this critical process is manually conducted by human inspectors, which can hardly provide a fast and reliable inspection results due to fatigue and subjective errors. To meet modern production needs, it is highly demanded to develop an automated defect inspection system by replacing human eyes with computer vision.
Design/methodology/approach
As a structural texture, fabric textures can be effectively represented by a linearly summation of basic elements (dictionary). To create a robust representation of a fabric texture in an unsupervised manner, a smooth constraint is imposed on dictionary learning model. Such representation is robust to defects when using it to recover a defective image. Thus an abnormal map (likelihood of defective regions) can be computed by measuring similarity between recovered version and itself. Finally, the total variation (TV) based model is built to segment defects on the abnormal map.
Findings
Different from traditional dictionary learning method, a smooth constraint is introduced in dictionary learning that not only able to create a robust representation for fabric textures but also avoid the selection of dictionary size. In addition, a TV based model is designed according to defects' characteristics. The experimental results demonstrate that (1) the dictionary with smooth constraint can generate a more robust representation of fabric textures compared to traditional dictionary; (2) the TV based model can achieve a robust and good segmentation result.
Originality/value
The major originality of the proposed method are: (1) Dictionary size can be set as a constant instead of selecting it empirically; (2) The total variation based model is built, which can enhance less salient defects, improving segmentation performance significantly.
Details
Keywords
Conghua Wen, Fei Jia and Jianli Hao
Using intraday data, the authors explore the forecast ability of one high frequency order flow imbalance measure (OI) based on the volume-synchronized probability of informed…
Abstract
Purpose
Using intraday data, the authors explore the forecast ability of one high frequency order flow imbalance measure (OI) based on the volume-synchronized probability of informed trading metric (VPIN) for predicting the realized volatility of the index futures on the China Securities Index 300 (CSI 300).
Design/methodology/approach
The authors employ the heterogeneous autoregressive model for realized volatility (HAR-RV) and compare the forecast ability of models with and without the predictive variable, OI.
Findings
The empirical results demonstrate that the augmented HAR model incorporating OI (HARX-RV) can generate more precise forecasts, which implies that the order imbalance measure contains substantial information for describing the volatility dynamics.
Originality/value
The study sheds light on the relation between high frequency trading behavior and volatility forecasting in China's index futures market and reveals the underlying market mechanisms of liquidity-induced volatility.
Details
Keywords
Jianli Xie, Jiayuan Hu, Jundong Lu and Xinmin Li
The purpose of this paper was to study the corrosion control of B10 copper-nickel alloy using the LiOH-N2H4 compound inhibitors and to evaluate the feasibility of replacing the…
Abstract
Purpose
The purpose of this paper was to study the corrosion control of B10 copper-nickel alloy using the LiOH-N2H4 compound inhibitors and to evaluate the feasibility of replacing the original inhibitors (NaNO2-Na2MoO4) with the new ones (LiOH-N2H4) for the chilled water system in a nuclear unit.
Design/methodology/approach
The corrosion resistance performance of B10 copper-nickel alloy was evaluated during the whole replacement process of inhibiters using electrochemical tests and surface analysis techniques.
Findings
The results indicated that the corrosion of B10 copper-nickel alloy could be prevented effectively using LiOH to increase the pH value of solution higher than 10.0 and using N2H4 to consume dissolved oxygen. During the replacement process of inhibitors from NaNO2-Na2MoO4 to LiOH-N2H4, the corrosion resistance performance of B10 copper-nickel alloy had not decreased greatly. The new LiOH-N2H4 inhibitor, which could enhance the compactness of rust, was able to reduce the corrosion rate of rusted B10 metal.
Originality/value
It is feasible and operable to replace the NaNO2-Na2MoO4 inhibitors with the LiOH-N2H4 inhibitors for the corrosion prevention of B10 copper-nickel alloy. The research results can provide guidelines for the inhibitor selection of chilled water system in a nuclear unit.
Details
Keywords
Jianli Cui, Junping Duan, Binzhen Zhang and Xueli Nan
This paper aims to provide a fabrication and measurement of a highly stretchable pressure sensor with a “V-type” array microelectrode on a grating PDMS substrate.
Abstract
Purpose
This paper aims to provide a fabrication and measurement of a highly stretchable pressure sensor with a “V-type” array microelectrode on a grating PDMS substrate.
Design/methodology/approach
First, the “V-type” array structure on the silicon wafer was fabricated by the MEMS technology, and the fabrication process included ultra-violet lithography and silicon etching. The “V-type” array structure on the master mold was then replicated into polycarbonate, which served as an intermediate, negative mold, using a conventional nanoimprint lithography technique. The negative mold was subsequently used in the PDMS molding process to produce PDMS “V-type” array structures with the same structures as the master mold. An Ag film was coated on the PDMS “V-type” array structure surface by the magnetron sputtering process to obtain PDMS “V-type” array microelectrodes. Finally, a PDMS prepolymer was prepared using a Sylgard184 curing agent with a weight ratio of a 20:1 and applied to the cavity at the middle of the two-layer PDMS “V-type” array microelectrode template to complete hot-press bonding, and a pressure sensor was realized.
Findings
The experimental results showed that the PDMS “V-type” array microelectrode has high stretchability of 65 per cent, temperature stability of 0.0248, humidity stability of 0.000204, bending stability and cycle stability. Capacitive pressure sensors with a “V-type” array microelectrode exhibit ideal initial capacitance (111.45 pF), good pressure sensitivity of 0.1143 MPa-1 (0-0.35 Mpa), fast response and relaxation times (<200 ms), high bending stability, high temperature/humidity stability and high cycle stability.
Originality/value
The PDMS “V-type” array structure microelectrode can be used to fabricate pressure sensors and is highly flexible, crack-free and durable.
Details
Keywords
Shun'an Cao, Jiayuan Hu, Jianli Xie, Qinqin Liang and Li Yin
The purpose of this paper is to set out a study of the film‐forming characteristics of octadecylamine (ODA), estimate the feasibility of shutdown protection using ODA at high…
Abstract
Purpose
The purpose of this paper is to set out a study of the film‐forming characteristics of octadecylamine (ODA), estimate the feasibility of shutdown protection using ODA at high temperatures, and determine the optimum process condition of shutdown protection for units under full load if ODA has a good film‐forming effect at high temperatures.
Design/methodology/approach
An autoclave was used to simulate the water‐vapor environments at 350‐560°C in the water‐steam system of power plants. The decomposition test of ODA was investigated and the ODA film‐forming characteristics were studied for furnace tube materials used in gas‐fired power plants.
Findings
Results showed that ODA had a decomposition equilibrium and the decomposition products did not contain harmful organic substances such as low molecular organic acids. ODA would form a satisfactory protective film in the range of 350‐560°C with the best film at 480°C. The protection effect of the film formed by ODA at 560°C was much stronger than was that of its oxide film, which showed the feasibility of shutdown protection using ODA for gas‐fired power plants operating under full load. The optimal conditions of shutdown protection under full load were as follows: the temperature was 560°C, the concentration of ODA was 80 mg/L, the pH was 9.5 and the exposure time was 2 h. From the experimental results of X‐ray photoelectron spectroscopy, it was known that the surface film on the specimens was composed of a compound of ferroferric oxide and ODA, and the film‐forming mechanism was chemical adsorption between N in the ODA and Fe.
Originality/value
It was found that ODA has a good film‐forming effect at high temperatures and it is practicable to implement shutdown protection for base‐load units. The research results can provide theoretical guidelines for shutdown protection of gas‐fired power plants.
Details
Keywords
Song Weiwei, Xiaojing Xu, Dunwen Zuo and Jianli Wang
This paper aims to investigate the modification of surface of a copper alloy by friction stir surface processing (FSSP).
Abstract
Purpose
This paper aims to investigate the modification of surface of a copper alloy by friction stir surface processing (FSSP).
Design/methodology/approach
The metallographic condition of the surface modification was observed using microscopy. Electrochemical corrosion tests were carried out on the modified surface and the corroded surface was observed by scanning electron microscopy (SEM).
Findings
The test results showed that FSSP resulted in refinement of the surface grains of the copper alloy. The degree of refinement was increased with rotation speed and increased in the descending distance of the stirring tool. The corrosion resistance of the modified surface was superior to the base metal except for the surface generated by a rotation speed of 800 rpm and a descending distance 0.1 mm. For the surface modification of the rotation speed of 800 rpm, its corrosion resistance was lower than for the other two rotation speeds. When the rotation speed is specified, the corrosion resistance is improved with increased descending distance. When the descending distance is specified, the corrosion resistance is improved with the rotation speed.
Originality/value
In this study, it was confirmed that the corrosion resistance of the surface modification was best at the rotation speed 1200 rpm and descending distance 0.2 mm.
Details
Keywords
Tong Feng, Shuanghui Hao, Minghui Hao and Jianli Wang
As a type of angular displacement sensor, the Hall-effect magnetic encoder incorporates many advantages. While compared with the photoelectric encoder, the magnetic encoder…
Abstract
Purpose
As a type of angular displacement sensor, the Hall-effect magnetic encoder incorporates many advantages. While compared with the photoelectric encoder, the magnetic encoder nevertheless has lower precision and lower resolution. So, the purpose of this essay is to find a way to increase the precision and resolution of the magnetic encoder.
Design/methodology/approach
By combining a single-pole magnetic encoder and a multi-pole AlNiCo magnet, the precision and resolution of this combined magnetic encoder are increased without increasing its volume or complicating its structure. A special algorithm system is developed to ensure faithful encoding and decoding.
Findings
Tests show that the combined magnetic encoder, with a diameter of 67.12 mm (including shaft) and thickness of 6.9 mm, has a precision of ±6′, compared with a 15-bit photoelectric encoder and a static resolution of ±0.6′.
Originality/value
This new kind of magnetic encoder could be used in specialized fields which need high-precision servo-control systems that are small, have ultra-low-speed and high-speed ratios and are non-oil-polluting or shock-resistant.
Details
Keywords
Abstract
Details
Keywords
Yong Qian, Hongying Gong, Xiaoyun Zhao, Lei Cao, Weizhong Shi and Jianli He
The purpose of this study is to corroborate the advanced tribological properties of graphene as a lubricant additive.
Abstract
Purpose
The purpose of this study is to corroborate the advanced tribological properties of graphene as a lubricant additive.
Design/methodology/approach
Different concentrations of functionalized graphene were coated on the substrate surface. Tribological properties of the graphene lubricants were carried out by ball-on-disk tribology tests. Wear mechanism of functionalized graphene was studied by observing wear scars on the substrate surface. Finally, the wear resistance of modified graphene was calculated by calculating and analyzing the applied experimental conditions and the obtained experimental data.
Findings
The best concentration of graphene lubricant is 0.5 wt.% which shows the best tribological performance. And the coefficient of friction is 0.08. Compared with the dry friction condition, the coefficient of friction and wear rate of best graphene lubricant decreased by 80% and 82%.
Originality/value
The formula of graphene lubricant is independently developed and works very well. Graphene lubricant can prevent the substrate from oxidation. The thickness of the graphene lubricant is about 4-7µm. The concept of anti-wear strength was introduced in this paper. When 0.5 Vol.% graphene was added, the anti-wear strength was greatly improved from 115.3 kg·mm-2 to 657.6 kg·mm-2.
Peer review
The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0344
Details
Keywords
The purpose of this paper is to develop and apply accurate and original models to understand and analyze the effects of the fabrication temperatures on thermal-induced stress and…
Abstract
Purpose
The purpose of this paper is to develop and apply accurate and original models to understand and analyze the effects of the fabrication temperatures on thermal-induced stress and speed performance of nano positively doped metal oxide semiconductor (pMOS) transistors.
Design/methodology/approach
The speed performances of nano pMOS transistors depend strongly on the mobility of holes, which itself depends on the thermal-induced extrinsic stress σ. The author uses a finite volume method to solve the proposed system of partial differential equations needed to calculate the thermal-induced stress σ accurately.
Findings
The thermal extrinsic stress σ depends strongly on the thermal intrinsic stress σ0, thermal intrinsic strain ε0, elastic constants C11 and C12 and the fabrication temperatures. In literature, the effects of fabrication temperatures on C11 and C12 needed to calculate thermal-induced stress σ0 have been ignored. The new finding is that if the effects of fabrication temperatures on C11 and C12 are ignored, then, the values of stress σ0 and σ will be overestimated and, then, not accurate. Another important finding is that the speed performance of nano pMOS transistors will increase if the fabrication temperature of silicon-germanium films used as stressors is increased.
Practical implications
To predict correctly the thermal-induced stress and speed performance of nano pMOS transistors, the effects of fabrication temperatures on the elastic constants required to calculate the thermal-induced intrinsic stress σ0 should be taken into account.
Originality/value
There are three levels of originalities. The author considers the effects of the fabrication temperatures on extrinsic stress σ, intrinsic stress σ0 and elastic constants C11 and C12.
Details