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Article
Publication date: 5 December 2023

Shahe Liang, Zhiqiang Zhang and Aiqun Li

A new type of variable damping viscous damper is developed to meet the settings of different damping parameter values at different working stages. Its main principle and design…

112

Abstract

Purpose

A new type of variable damping viscous damper is developed to meet the settings of different damping parameter values at different working stages. Its main principle and design structure are introduced, and the two-stage and multi-stage controllable damping methods are proposed.

Design/methodology/approach

The theoretical calculation formulas of the damping force of power-law fluid variable damping viscous damper at elongated holes are derived, aiming to provide a theoretical basis for the development and application of variable damping viscous dampers. For the newly developed variable damping viscous damper, the dynamic equations for the seismic reduction system with variable damping viscous dampers under a multi-degree-of-freedom system are established. A feasible calculation and analysis method is proposed to derive the solution process of time history analysis. At the same time, a program is also developed using Matlab. The dynamic full-scale test of a two-stage variable damping viscous damper was conducted, demonstrating that the hysteresis curve is complete and the working condition is stable.

Findings

Through the calculation and analysis of examples, the results show that the seismic reduction effect of high and flexible buildings using the seismic reduction system with variable damping viscous dampers is significant. The program developed is used to analyze the seismic response of a broadcasting tower using a variable damping TMD system under large earthquakes. The results indicate that the installation of variable damping viscous dampers can effectively control the maximum inter-story displacement response of TMD water tanks and can effectively consume seismic energy.

Originality/value

This method can provide a guarantee for the safe and effective operation of TMD in wind and vibration control.

Details

International Journal of Structural Integrity, vol. 15 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

Available. Open Access. Open Access
Article
Publication date: 29 August 2023

Yangsheng Ye, Degou Cai, Qianli Zhang, Shaowei Wei, Hongye Yan and Lin Geng

This method will become a new development trend in subgrade structure design for high speed railways.

570

Abstract

Purpose

This method will become a new development trend in subgrade structure design for high speed railways.

Design/methodology/approach

This paper summarizes the structural types and design methods of subgrade bed for high speed railways in China, Japan, France, Germany, the United States and other countries based on the study and analysis of existing literature and combined with the research results and practices of high speed railway subgrade engineering at home and abroad.

Findings

It is found that in foreign countries, the layered reinforced structure is generally adopted for the subgrade bed of high speed railways, and the unified double-layer or multi-layer structure is adopted for the surface layer of subgrade bed, while the simple structure is adopted in China; in foreign countries, different inspection parameters are adopted to evaluate the compaction state of fillers according to their respective understanding and practice, while in China, compaction coefficient, subsoil coefficient and dynamic deformation modulus are adopted for such evaluation; in foreign countries, the subgrade top deformation control method, the subgrade bottom deformation control method, the subsurface fill strength control method are mainly adopted in subgrade bed structure design of high speed railways, while in China, dynamic deformation control of subgrade surface and dynamic strain control of subgrade bed bottom layer is adopted in the design. However, the cumulative deformation of subgrade caused by train cyclic vibration load is not considered in the existing design methods.

Originality/value

This paper introduces a new subgrade structure design method based on whole-process dynamics analysis that meets subgrade functional requirements and is established on the basis of the existing research at home and abroad on prediction methods for cumulative deformation of subgrade soil.

Details

Railway Sciences, vol. 2 no. 3
Type: Research Article
ISSN: 2755-0907

Keywords

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Article
Publication date: 1 April 2001

M. Xie, T.N. Goh and D.Q. Cai

Control charts have been widely used in the manufacturing industry as the most important statistical process control (SPC) technique. One assumption for successfully applying…

1524

Abstract

Control charts have been widely used in the manufacturing industry as the most important statistical process control (SPC) technique. One assumption for successfully applying control charts is that the process is stable to begin with and adjustments are made only at a later point when the process is deemed to be out of control. A situation that often arises is when the process is subject to a slow trend caused by factors such as equipment deterioration, power decline during its consumption, or other reasons. For this type of situation, an integrated monitoring and adjustment approach can be considered and the relevant issues involved are discussed in this paper. This problem of implementing SPC is studied from the point of view of process management, together with the concept of engineering process control. A general approach is then formulated for monitoring processes with trend and subject to regular adjustments and a specific model for a general case with linear trend is studied in more detail.

Details

Integrated Manufacturing Systems, vol. 12 no. 2
Type: Research Article
ISSN: 0957-6061

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Article
Publication date: 11 September 2011

Er‐shun Pan, Yao Jin and Ying Wang

The purpose of this paper is to develop an extensive economic production quantity (EPQ) model on the basis of previous research. Considering an imperfect three‐state production…

616

Abstract

Purpose

The purpose of this paper is to develop an extensive economic production quantity (EPQ) model on the basis of previous research. Considering an imperfect three‐state production process, this paper makes contributions to an integrated model combining conceptions of quality loss and design of control chart based on EPQ model. The objective is to minimize the total production cost with the determination of EPQ and design parameters of control chart subjected to quality loss and other process costs.

Design/methodology/approach

In this paper, imperfect process is defined as a three‐state process, and the quality cost corresponding to each state contributes to the eventual total expected cost formulation. Control chart is used to monitor the shift from the target value within whole process and its control limits are set to be related to the quality cost.

Findings

The proposed integrated model conforms more closely to the real situation of production process considering the process shift as a random variable.

Practical implications

Numerical computation and sensitivity analysis through a case study are presented to demonstrate the applications of the model.

Originality/value

Few research efforts investigate an integrated model considering EPQ, control chart and quality loss simultaneously. In particular, compared with the former researches, the process shift, due to which the quality cost incurs, is considered as a random variable in this paper.

Details

Journal of Manufacturing Technology Management, vol. 22 no. 7
Type: Research Article
ISSN: 1741-038X

Keywords

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Article
Publication date: 4 December 2017

Wu Deng, Meng Sun, Huimin Zhao, Bo Li and Chunxiao Wang

This study aims to propose a new airport gate assignment method to effectively improve the comprehensive operation capacity and efficiency of hub airport. Gate assignment is one…

683

Abstract

Purpose

This study aims to propose a new airport gate assignment method to effectively improve the comprehensive operation capacity and efficiency of hub airport. Gate assignment is one of the most important tasks for airport ground operations, which assigns appropriate airport gates with high efficiency reasonable arrangement.

Design/methodology/approach

In this paper, on the basis of analyzing the characteristics of airport gates and flights, an efficient multi-objective optimization model of airport gate assignment based on the objectives of the most balanced idle time, the shortest walking distances of passengers and the least number of flights at apron is constructed. Then an improved ant colony optimization (ICQACO) algorithm based on the ant colony collaborative strategy and pheromone update strategy is designed to solve the constructed model to fast realize the gate assignment and obtain a rational and effective gate assignment result for all flights in the different period.

Findings

In the designed ICQACO algorithm, the ant colony collaborative strategy is used to avoid the rapid convergence to the local optimal solution, and the pheromone update strategy is used to quickly increase the pheromone amount, eliminate the interference of the poor path and greatly accelerate the convergence speed.

Practical implications

The actual flight data from Guangzhou Baiyun airport of China is selected to verify the feasibility and effectiveness of the constructed multi-objective optimization model and the designed ICQACO algorithm. The experimental results show that the designed ICQACO algorithm can increase the pheromone amount, accelerate the convergence speed and avoid to fall into the local optimal solution. The constructed multi-objective optimization model can effectively improve the comprehensive operation capacity and efficiency. This study is a very meaningful work for airport gate assignment.

Originality/value

An efficient multi-objective optimization model for hub airport gate assignment problem is proposed in this paper. An improved ant colony optimization algorithm based on ant colony collaborative strategy and the pheromone update strategy is deeply studied to speed up the convergence and avoid to fall into the local optimal solution.

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Article
Publication date: 20 June 2017

Chor Yen Yap, Hongyi Kenneth Tan, Zhenglin Du, Chee Kai Chua and Zhili Dong

Selective laser melting (SLM) is an additive manufacturing technology that is gaining industrial and research interest as it can directly fabricate near full density metallic…

1007

Abstract

Purpose

Selective laser melting (SLM) is an additive manufacturing technology that is gaining industrial and research interest as it can directly fabricate near full density metallic components. The paper aims to identify suitable process parameters for SLM of processing of pure nickel powder and to study the microstructure of such products. The study also aims to characterize the microhardness and tensile properties of pure nickel produced by SLM.

Design/methodology/approach

A 24 factorial design experiment was carried out to identify the most significant factors on the resultant porosity of nickel parts. A subsequent experiment was carried out with a laser power of 350 W. The scanning speeds and hatch spacings were varied.

Findings

Scanning speed and hatch spacing have significant effects on the porosity of SLM components. A high relative density of 98.9 per cent was achieved, and microhardness of 140 to 160 Hv was obtained from these samples. A tensile strength 452 MPa was obtained.

Research limitations/implications

As the energy input levels were made in steps of 20 J/mm3 for the optimization study, the true optimal combination of parameters may have been missed. Therefore, researchers are encouraged to test the parameters with smaller variations in energy levels.

Practical implications

The paper provides a set of optimized parameters for the SLM of pure nickel. This study enables the three-dimensional (3D) printing of objects with nickel, which has applications in chemical catalyses and in microelectromechanical systems with its magnetostrictive properties.

Originality value

This research is the first in direct processing of pure nickel using SLM, with the identification of suitable process parameters. The study also provides an understanding of the porosity, microhardness, strength and microstructure of SLM produced nickel parts. This work paves the way for standardization of 3D printed nickel components and enables the applications of pure nickel via SLM.

Details

Rapid Prototyping Journal, vol. 23 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

Available. Open Access. Open Access
Article
Publication date: 21 March 2023

Shilei Wang, Zhan Peng, Guixian Liu, Weile Qiang and Chi Zhang

In this paper, a high-frequency radar test system was used to collect the data of clean ballast bed and fouled ballast bed of ballasted tracks, respectively, for a quantitative…

463

Abstract

Purpose

In this paper, a high-frequency radar test system was used to collect the data of clean ballast bed and fouled ballast bed of ballasted tracks, respectively, for a quantitative evaluation of the condition of railway ballast bed.

Design/methodology/approach

Based on original radar signals, the time–frequency characteristics of radar signals were analyzed, five ballast bed condition characteristic indexes were proposed, including the frequency domain integral area, scanning area, number of intersections with the time axis, number of time-domain inflection points and amplitude envelope obtained by Hilbert transform, and the effectiveness and sensitivity of the indexes were analyzed.

Findings

The thickness of ballast bed tested at the sleep bottom by high-frequency radar is up to 55 cm, which meets the requirements of ballast bed detection. Compared with clean ballast bed, the values of the five indexes of fouled ballast bed are larger, and the five indexes could effectively show the condition of the ballast bed. The computational efficiency of amplitude envelope obtained by Hilbert transform is 140 s·km−1, and the computational efficiency of other indexes is 5 s·km−1. The amplitude envelopes obtained by Hilbert transform in the subgrade sections and tunnel sections are the most sensitive, followed by scanning area. The number of intersections with the time axis in the bridge sections was the most sensitive, followed by the scanning area. The scanning area can adapt to different substructures such as subgrade, bridges and tunnels, with high comprehensive sensitivity.

Originality/value

The research can provide appropriate characteristic indexes from the high-frequency radar original signal to quantitatively evaluate ballast bed condition under different substructures.

Details

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

Keywords

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Article
Publication date: 1 October 2003

Shamsuddin Ahmed and Masjuki Hassan

Quality management (QM) cannot be assured unless some objective assessments are undertaken. A number of tools and techniques are available to conduct such analysis. Although some…

6694

Abstract

Quality management (QM) cannot be assured unless some objective assessments are undertaken. A number of tools and techniques are available to conduct such analysis. Although some of them are product or service specific, however, a few basic tools and techniques are commonly used in manufacturing firms. This study focuses on the state of application of QM tools and techniques in small and medium industries (SMIs). The findings reveal that by‐and‐large, lack of methodical analysis is a major weakness of SMIs. Still some rule‐of‐thumb and subjective observations are dominating over objective evaluation in the process of quality control decisions. A few case studies which have been conducted, and one that has been briefly reported here, also support this conclusion. The methodology of the study has three folds: literature review, survey in SMIs and case studies.

Details

International Journal of Quality & Reliability Management, vol. 20 no. 7
Type: Research Article
ISSN: 0265-671X

Keywords

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Article
Publication date: 14 August 2019

Abdelaziz S. Fouda, Mohamed A. Ismail, Rabab M. Abou-shahba, Walaa A. Hussein, Esraa S. El-habab and Ashraf S. Abousalem

The purpose of this paper is to investigate three Arylfuranylnicotinamidine derivatives against corrosion of carbon steel (C-steel) in 1.0 M HCl by chemical and electrochemical…

97

Abstract

Purpose

The purpose of this paper is to investigate three Arylfuranylnicotinamidine derivatives against corrosion of carbon steel (C-steel) in 1.0 M HCl by chemical and electrochemical means. The inhibition efficiency (%IE) increases with increasing the dose of inhibitors. The tested compounds exhibited improved performance at elevated temperature, with %IE reaching 93 percent at 21 µM. Tafel polarization method revealed that the tested compounds act as mixed-type inhibitors. The inhibition action was rationalized due to chemical adsorption of inhibition molecules on C-steel surface following Temkin’s isotherm. Surface examination was carried out by AFM and FTIR techniques. Further, theoretical chemical approaches were used to corroborate the experimental findings.

Design/methodology/approach

Experimental and computational methods were applied to investigate the efficiency of these new compounds. These studies are complemented with spectral studies and surface morphological scan by AFM. The theoretical results indicate good correlation with experimental findings.

Findings

The tested derivatives are promising corrosion inhibitors for C-steel in the acid environment. The molecular scaffold of this class of compounds can be used to design new highly efficient inhibitors by screening its activity by modeling studies.

Originality/value

The studied compounds are safe inhibitors and greatly adsorbed on Fe surface. The action of compounds is enhanced with temperature, which means these compounds can be used in higher temperature systems. The new compounds are effective at very low concentration.

Details

Multidiscipline Modeling in Materials and Structures, vol. 15 no. 6
Type: Research Article
ISSN: 1573-6105

Keywords

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Article
Publication date: 17 January 2020

Do Xuan Luan

The purpose of this paper is to investigate borrowing motivation, credit access barriers and their impacts on income of smallholder farmers engaging in cinnamon value chain…

311

Abstract

Purpose

The purpose of this paper is to investigate borrowing motivation, credit access barriers and their impacts on income of smallholder farmers engaging in cinnamon value chain development in Northwestern Vietnam.

Design/methodology/approach

A multistage sampling technique using a structural questionnaire and in-depth interviews was applied for collecting primary data from farmers and relevant stakeholders. The Propensity Score Matching was employed to analyze access barriers and examine whether relaxing these barriers can improve farmer income. To deal with the issue of model uncertainty and further increase the robustness of results, Bayesian model average and the bootstrapping approach were applied.

Findings

To fulfill the certain quality standards of cinnamon products which are later used in the medicinal and food industry, farmers as primary producers need credit for intensive investment to increase the value of their products. Still, there are 25.36 percent of farmers who have access constraints to formal credit. In the credit received group, 24.56 percent have not received full credit as demanded. Access problems are relevant to lack of collateral, lack of bank account holdings, inconvenient access to roads, weak chain linkage and limited organic farming. Removing credit access barriers can improve the income for farmers from cinnamon farming activities.

Research limitations/implications

More detailed information on the conditions under which credit serves a more important role in creating value addition for cinnamon products can help the government establish more effective credit policies.

Social implications

Great attention should be paid to smallholder farmers as primary producers in the chain for sustainable value chain development in developing and emerging economies. Policy interventions should facilitate access to bank accounts, speed up the process of granting residential land use certificates, certify organic farming and upgrade the road system. Strengthening the chain linkage can enhance smallholder farmers’ capacity to obtain credit through value chain lending development.

Originality/value

Empirical studies on agricultural credit from the perspective of value chain development remain scarce. A better understanding of credit access constraints allows for the positing of recommendations for policy makers to facilitate value chain lending and a medicinal plant-based agro-forestry system in similar situations.

Details

Journal of Agribusiness in Developing and Emerging Economies, vol. 10 no. 2
Type: Research Article
ISSN: 2044-0839

Keywords

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