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Article
Publication date: 10 May 2018

Hongyan Shi, Xiaoke Lin, Qiuxin Yan and Xiong Liang

The purpose of this paper was to study the influence of properties of printed circuit boards (PCBs) on the temperature during micro drilling and obtain the influential mechanism…

Abstract

Purpose

The purpose of this paper was to study the influence of properties of printed circuit boards (PCBs) on the temperature during micro drilling and obtain the influential mechanism of PCBs based on temperature measurement.

Design/methodology/approach

Experiments were carried out to study the influence mechanism of PCB properties on micro hole drilling temperature under high spindle speed. The temperature measurement platform was applied, then the influence of components ratio of PCBs on the temperature of micro-drilling was analyzed by using comparative analysis method. The mass ratio of each kind of material in the PCB was defined as four levels and the influence mechanism of properties of PCBs based on temperature measurement was summarized.

Findings

Average filler and lower resin would have a positive impact on micro hole drilling temperature, and the smaller filler size and the even distribution would make it better.

Originality/value

An infrared temperature measurement platform was applied and influential mechanism of PCB properties on temperature was analyzed, which could provide the reference value on the optimization of temperature during micro drilling.

Details

Circuit World, vol. 44 no. 3
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 4 March 2021

Jung-Chieh Lee and Liang Nan Xiong

Numerous educational applications (APP) have been developed to assist traditional classroom teaching and student learning. APP quality plays a critical role in influencing…

Abstract

Purpose

Numerous educational applications (APP) have been developed to assist traditional classroom teaching and student learning. APP quality plays a critical role in influencing students' learning behaviors. However, the role negative mindsets, especially computer anxiety, play in how APP quality affects student engagement remains unknown. To address the relationships among APP quality, computer anxiety and student engagement in an APP-based learning environment, we developed an extended information system (IS) success model that includes interface and instructor quality.

Design/methodology/approach

To empirically test the proposed model, we conducted a survey with a sample of 225 university students and examined the hypotheses using the partial least squares (PLS) method.

Findings

Computer anxiety was demonstrated to fully mediate the relationships between student engagement and interface quality and service quality and system quality. In addition, the instructor quality acts as a partial mediator of the relationship between computer anxiety and student engagement.

Originality/value

This study reveals the important mediating role of computer anxiety in APP-assisted learning and the special status of instructor quality and user experience in influencing student engagement. The findings of this study shed meaningful light on the practical implications for instructors and APP software developers.

Details

Online Information Review, vol. 46 no. 1
Type: Research Article
ISSN: 1468-4527

Keywords

Article
Publication date: 5 May 2015

Xiong Liang, Bing Li, Lianyu Fu, Xiaoyu Wu, Hongyan Shi, Taijiang Peng and Bin Xu

This paper aims to present the main factors affecting the mechanical drilling of the printed circuit board (PCB for short) micro-holes and method of micro-ultrasonic powder…

1056

Abstract

Purpose

This paper aims to present the main factors affecting the mechanical drilling of the printed circuit board (PCB for short) micro-holes and method of micro-ultrasonic powder molding (micro-UPM for short) by utilizing PCB micro-hole array.

Design/methodology/approach

To optimize the drilling process, the paper proposes the on-line monitoring methods for the drilling process including drilling force, drilling temperature, high-speed photography and vibration signals. Taking 0.10 and 0.15 mm micro-drilling as examples, the paper analyzes the drilling process of ultra-small micro-holes. Finally, by taking the PCBs with 0.10 and 0.15 mm micro-hole arrays as the micro-cavity inserts, utilizing ultra-high-molecule weight polyethylene powder with the average particle size of about 150 μm as raw material, two sizes of micro-cylinder array polymer parts are fabricated through micro-UPM process.

Findings

PCB micro-cavity inserts with micro-hole arrays fabricated by mechanical drilling has the advantages of low costs, high efficiency and good consistency. Taking 0.10 and 0.15 mm micro-drilling as examples, it is found that the both measured apertures are about 10.0 μm more than the diameter of the micro-drill bits on average. The average diameter of the micro-cylinders by micro-UPM process is smaller than that of the micro-hole with the same specification, while the value of the roughness of the cylinder surface is more than that of the hole-wall surface with the same specification.

Originality/value

This paper describes the challenges and the developments of mechanical drilling and by using PCB micro-cavity inserts with micro-hole arrays fabricated by mechanical drilling, two different micro-cylinder array polymer parts are successfully made and thus the application area of PCB micro-drilling is broadened.

Details

Circuit World, vol. 41 no. 2
Type: Research Article
ISSN: 0305-6120

Keywords

Article
Publication date: 10 May 2013

Xiong Liang, Bing Li, Xiaoyu Wu, Hongyan Shi, Kun Zeng and Yatao Wang

The purpose of this paper is to present a method for ultrasonically molding polymer powder in a micro plastic part mold. In the method, a printed circuit board (PCB) in which…

Abstract

Purpose

The purpose of this paper is to present a method for ultrasonically molding polymer powder in a micro plastic part mold. In the method, a printed circuit board (PCB) in which micro‐hole arrays are drilled is used as a micro cavity insert. With the utilization of ultrasonic vibration, the polymer powder, which is prefilled and compacted in a micro cavity, mutually generates great sliding friction heat so as to be rapidly plasticized and molded.

Design/methodology/approach

Micro carbide drill bits of which the diameters are 100.0 μm, 150.0 μm and 200.0 μm, respectively, are used for drilling the PCB to form a micro‐hole array insert. Next, two kinds of various ultra‐high molecule weight polyethylene (UHMW‐PE) powder with various grain diameters are directly filled into a charging barrel and a mold cavity with the micro‐hole array insert. Proper process parameters are set on ultrasonic plasticizing and molding equipment so that a molding test can be performed. The melt of UHMW‐PE can be rapidly filled into the cavity. Finally, micro‐column array plastic parts are successfully prepared.

Findings

The micro‐hole array PCB is a mold insert which is quite applicable for the ultrasonic molding of the powder in the mold. When a molding material is the coarse UHMW‐PE powder with the grain diameter of about 350 μm, the diameter replication rates of the micro‐column array plastic parts become good in order with the increased micro‐hole diameter of the PCB. When the fine UHMW‐PE powder with the grain diameter of about 80 μm is adopted, the diameter replication rates of the micro‐column array plastic parts become good in order with the decreased micro‐hole diameter of the PCB.

Originality/value

In this paper, the micro‐column array plastic parts with good replicability are successfully prepared by a technique for ultrasonically plasticizing and molding in the cavity. The technique can be applied to the fields of medical treatment, communication, optics, chemistry and so on, such as biological micro needle arrays, micro biological chips, optical memories, and micro chemical reaction chips.

Article
Publication date: 13 October 2022

Xiaomeng Zhang, Sang Xiong, Feng Gao, Jinyuan Du and Qin-Jian Du

WO3 particles were prepared by the sol-gel method. Tetraethyl silicate (TEOS) was used to obtain a SiO2-coated WO3 nanoparticle. Quantum chemical parameters of oleic acid…

Abstract

Purpose

WO3 particles were prepared by the sol-gel method. Tetraethyl silicate (TEOS) was used to obtain a SiO2-coated WO3 nanoparticle. Quantum chemical parameters of oleic acid, triethanolamine, glycerol and methyl pentane as dispersants were theoretically calculated. Tribological properties of SiO2/WO3 nanocomposite lubricant were carried out on an MRS-10A four-ball friction and wear tester.

Design/methodology/approach

The purpose of this study is to investigate the preparation and tribological properties of SiO2/WO3 nanocomposite lubricant.

Findings

The obtained SiO2-coated WO3 nanoparticle (nano-SiO2/WO3) with a particle size of about 70 nm. The calculated adsorption energy of triethanolamine on the surface of the steel ball is 554.6 eV, and triethanolamine is selected as the dispersant. The dispersion effect of SiO2/WO3 nanocomposite lubricant is good, which shows that triethanolamine oleate plays a good dispersion role in the preparation of lubricant, which is consistent with the calculation results of the adsorption capacity of dispersant. As a good auxiliary lubricant, SiO2 can improve the tribological properties and wear resistance of WO3.

Originality/value

Nanocomposite lubricants have been the focus of research in recent years, which could greatly reduce energy consumption. And the SiO2/WO3 exhibited excellent lubrication performance as a lubricant additive. The lubrication mechanism of SiO2/WO3 nanocomposite lubricant is the synergistic lubrication mechanism of friction film lubrication and antifriction bearing. This study could provide a certain reference for the practical application of nanocomposite lubricants.

Details

Industrial Lubrication and Tribology, vol. 75 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Content available
Book part
Publication date: 23 September 2019

Yi-Ming Wei, Qiao-Mei Liang, Gang Wu and Hua Liao

Abstract

Details

Energy Economics
Type: Book
ISBN: 978-1-83867-294-2

Article
Publication date: 30 April 2021

Shengyu Guo, Yujia Zhao, Yuqiu Luoren, Kongzheng Liang and Bing Tang

Knowledge discovery related to unsafe behaviors promotes the performance of accident prevention in construction. Although numerous studies on accident causation models have…

Abstract

Purpose

Knowledge discovery related to unsafe behaviors promotes the performance of accident prevention in construction. Although numerous studies on accident causation models have discussed the correlations of unsafe behaviors with various factors (e.g., unsafe conditions), limited research explores correlations between unsafe behaviors within accidents. The purpose of this paper is mining strong association rules of unsafe behaviors from historical accidents to clarify this kind of tacit knowledge.

Design/methodology/approach

A case study was adopted as the research approach, in which accident records from building and urban railway construction in China were selected as data resources. The groups of unsafe behaviors extracted from accident records were expressed by the definitions of unsafe behaviors from safety regulations and operating procedures. Frequent Pattern (FP)-Growth algorithm was used for association rule mining, and the critical correlations between unsafe behaviors were represented by the effective strong rules.

Findings

The findings identify and distinguish correlations between unsafe behaviors within construction accidents. In building construction, workers and managers should pay attention to preventing unsafe behaviors related to personal protective equipment and machines and equipment. In urban railway construction, workers should especially avoid unsafe behaviors of inadequately dealing with environmental factors.

Practical implications

Tacit knowledge is transferred to explicit knowledge as the critical correlations between unsafe behaviors within accidents are determined by the effective strong rules. Additionally, the findings provide practice guidance for safety management, to collaboratively control unsafe behaviors with strong correlations.

Originality/value

This study contributes to the body of safety knowledge in construction and provides a further understanding of how construction accidents are caused by multiple unsafe behaviors.

Details

Engineering, Construction and Architectural Management, vol. 29 no. 4
Type: Research Article
ISSN: 0969-9988

Keywords

Article
Publication date: 12 February 2020

Sang Xiong, Jia Si, Jianlin Sun, Hao Wu, Hongchen Dong and Chao Zhang

Corrosion inhibitors for copper immersed in emulsion were investigated by experiments and theoretical calculations, and this study aims to propose a new inhibition mechanism of…

Abstract

Purpose

Corrosion inhibitors for copper immersed in emulsion were investigated by experiments and theoretical calculations, and this study aims to propose a new inhibition mechanism of the inhibitors having protective effects for copper corrosion.

Design/methodology/approach

Adsorption behavior of penta-heterocycles (thiophene, 1,2,5-oxadiazole, furan, 2 H-1,2,3-triazole, pyrrole and 1,2,5-thiadiazole) as corrosion inhibitors for copper immersed in oil-in-water (O/W) emulsions was investigated by weight loss, electrochemical tests, morphological characterization and theoretical calculations.

Findings

The orders of inhibition effect are furan < pyrrole < thiophene < 1,2,5-oxadiazole < 2H-1,2,3-triazole < 1,2,5-thiadiazole, and 1,2,5-thiadiazole at 0.5 mM has the best inhibition effect for copper immersed in emulsion. The results of scanning probe microscope, scanning electron microscope and electrochemical test show that a protective barrier can be formed on the surface of copper substrate with six corrosion inhibitors, thus effectively inhibiting the corrosion of copper mainly through chemisorption and following Langmuir’s adsorption isotherm.

Originality/value

Quantum chemical and molecular dynamic simulations demonstrate that all these compounds attached to Cu matrix with a flat-adsorption mode to prevent the emulsion corrode copper. Adsorbed inhibitors act as a barrier at Cu matrix to block corrosion and improve hydrophobicity.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 12 August 2020

Fangfang Liu, Yousong Wang, Hongyang Li and Xiaowei Zhou

The purpose of the study is to numerically investigate the relationship between the increase in transaction cost and prolongation of cooperative period acting as a nonmonetary…

Abstract

Purpose

The purpose of the study is to numerically investigate the relationship between the increase in transaction cost and prolongation of cooperative period acting as a nonmonetary incentive for municipal PPP projects.

Design/methodology/approach

A model that combines real option theory and the concept of prospect theory is proposed in the study. Three municipal road PPP projects published by China Public Private Partnerships Center are selected as cases. The data of these cases are analyzed based on the model established.

Findings

The prolongation of the cooperative period affects the increase in transaction cost, which gradually decreases when the prolonged cooperative period increases. Furthermore, the large-investment PPP projects own more transaction cost compared with less-investment projects. The decrease in transaction cost in the former is less than that in the latter. The increase in transaction cost is evidently alleviated in a project with less investment when the cooperative period is prolonged further.

Originality/value

The study systematically analyzes the relationship among transaction cost economics, real option theory and prospect theory and proposes a theoretical flowchart of the effect of nonmonetary incentive on the transaction cost. A model to quantify the effect of nonmonetary incentive (i.e. prolongation of cooperative period) on the transaction cost is proposed for the first time. The results of the study verify that the nonmonetary incentive affects transaction cost.

Details

Engineering, Construction and Architectural Management, vol. 28 no. 4
Type: Research Article
ISSN: 0969-9988

Keywords

Open Access
Article
Publication date: 19 May 2022

Wenhua Guo, Xinmin Hong and Chunxia Chen

This paper aims to study the influence of aerodynamics force of trains passing each other on the dynamic response of vehicle bridge coupling system based on numerical simulation…

Abstract

Purpose

This paper aims to study the influence of aerodynamics force of trains passing each other on the dynamic response of vehicle bridge coupling system based on numerical simulation and multi-body dynamics and put forward the speed threshold for safe running of train under different crosswind speeds.

Design/methodology/approach

The computational fluid dynamics method is adopted to simulate the aerodynamic force in the whole process of train passing each other by using dynamic grid technology. The dynamic model of vehicle-bridge coupling system is established considering the effects of aerodynamic force of train passing each other under crosswind, the dynamic response of train intersection on the bridge under crosswind is computed and the running safety of the train is evaluated.

Findings

The aerodynamic force of trains' intersection has little effects on the derailment factor, lateral wheel-rail force and vertical acceleration of train, but it increases the offload factor of train and significantly increases the lateral acceleration of train. The crosswind has a significant effect on increasing the derailment factor, lateral wheel-rail force and offload factor of train. The offload factor of train is the key factor to control the threshold of train speed. The impact of the aerodynamic force of trains' intersection on running safety cannot be ignored. When the extreme values of crosswind wind speed are 15 m·s−1, 20 m·s−1 and 25 m·s−1, respectively, the corresponding speed thresholds for safe running of train are 350 km·h−1, 275 km·h−1 and 200 km·h−1, respectively.

Originality/value

The research can provide a more precise numerical method to study the running safety of high-speed trains under the aerodynamic effect of trains passing each other on bridge in crosswind.

Details

Railway Sciences, vol. 1 no. 2
Type: Research Article
ISSN: 2755-0907

Keywords

1 – 10 of 967