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Article
Publication date: 14 September 2023

Yazhou Wang, Dehong Luo, Xuelin Zhang, Zhitao Wang, Hui Chen, Xiaobo Zhang, Ningning Xie, Shengwei Mei, Xiaodai Xue, Tong Zhang and Kumar K. Tamma

The purpose of this paper is to design a simple and accurate a-posteriori Lagrangian-based error estimator is developed for the class of backward differentiation formula (BDF…

87

Abstract

Purpose

The purpose of this paper is to design a simple and accurate a-posteriori Lagrangian-based error estimator is developed for the class of backward differentiation formula (BDF) algorithms with variable time step size, and the adaptive time-stepping in BDF algorithms is demonstrated for efficient time-dependent simulations in fluid flow and heat transfer.

Design/methodology/approach

The Lagrange interpolation polynomial is used to predict the time derivative, and then the accurate primary result is obtained by the Gauss integral, which is applied to evaluate the local error. Not only the generalized formula of the proposed error estimator is presented but also the specific expression for the widely applied BDF1/2/3 is illustrated. Two essential executable MATLAB functions to implement the proposed error estimator are appended for practical applications. Then, the adaptive time-stepping is demonstrated based on the newly proposed error estimator for BDF algorithms.

Findings

The validation tests show that the newly proposed error estimator is accurate such that the effectivity index is always close to unity for both linear and nonlinear problems, and it avoids under/overestimation of the exact local error. The applications for fluid dynamics and coupled fluid flow and heat transfer problems depict the advantage of adaptive time-stepping based on the proposed error estimator for time-dependent simulations.

Originality/value

In contrast to existing error estimators for BDF algorithms, the present work is more accurate for the local error estimation, and it can be readily extended to practical applications in engineering with a few changes to existing codes, contributing to efficient time-dependent simulations in fluid flow and heat transfer.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 33 no. 12
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 25 February 2022

Yazhou Wang, Ningning Xie, Likun Yin, Tong Zhang, Xuelin Zhang, Shengwei Mei, Xiaodai Xue and Kumar Tamma

The purpose of this paper is to describe a novel universal error estimator and the adaptive time-stepping process in the generalized single-step single-solve (GS4-1) computational…

151

Abstract

Purpose

The purpose of this paper is to describe a novel universal error estimator and the adaptive time-stepping process in the generalized single-step single-solve (GS4-1) computational framework, applied for the fluid dynamics with illustrations to incompressible Navier–Stokes equations.

Design/methodology/approach

The proposed error estimator is universal and versatile that it works for the entire subsets of the GS4-1 framework, encompassing the nondissipative Crank–Nicolson method, the most dissipative backward differential formula and anything in between. It is new and novel that the cumbersome design work of error estimation for specific time integration algorithms can be avoided. Regarding the numerical implementation, the local error estimation has a compact representation that it is determined by the time derivative variables at four successive time levels and only involves vector operations, which is simple for numerical implementation. Additionally, the adaptive time-stepping is further illustrated by the proposed error estimator and is used to solve the benchmark problems of lid-driven cavity and flow past a cylinder.

Findings

The proposed computational procedure is capable of eliminating the nonphysical oscillations in GS4-1(1,1)/Crank–Nicolson method; being CPU-efficient in both dissipative and nondissipative schemes with better solution accuracy; and detecting the complex physics and hence selecting a suitable time step according to the user-defined error threshold.

Originality/value

To the best of the authors’ knowledge, for the first time, this study applies the general purpose GS4-1 family of time integration algorithms for transient simulations of incompressible Navier–Stokes equations in fluid dynamics with constant and adaptive time steps via a novel and universal error estimator. The proposed computational framework is simple for numerical implementation and the time step selection based on the proposed error estimation is efficient, benefiting to the computational expense for transient simulations.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 32 no. 10
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 27 January 2025

Yazhou Wang, Kumar K. Tamma, Dean J. Maxam and Tao Xue

This paper aims to design and analyze implicit/explicit/semi-implicit schemes and a universal error estimator within the Generalized Single-step Single-Solve computational…

25

Abstract

Purpose

This paper aims to design and analyze implicit/explicit/semi-implicit schemes and a universal error estimator within the Generalized Single-step Single-Solve computational framework for First-order transient systems (GS4-I), which also fosters the adaptive time-stepping procedure to improve stability, accuracy and efficiency applied for fluid dynamics.

Design/methodology/approach

The newly proposed child-explicit and semi-implicit schemes emanate from the parent implicit GS4-I framework, providing numerous options with flexible and controllable numerical properties to the analyst. A universal error estimator is developed based on the consistent algorithmic variables and it works for all the developed methods. Applications are demonstrated by merging the developed algorithms into the iterated pressure-projection method for incompressible Navier–Stokes equations.

Findings

The child-explicit GS4-I has improved solution accuracy and stability properties, and the most stable option is the child explicit GS4-I(0,0)/second-order backward differentiation formula/Gear’s methods, which is new and novel. Numerical tests validate that the universal error estimator emanating from implicit designs works well for the newly proposed explicit/semi-implicit algorithms. The iterative pressure-correction projection algorithm is efficiently fostered by the error estimator-based adaptive time-stepping.

Originality/value

The implicit/explicit/semi-implicit methods within a unified computational framework are easy to implement and have flexible options in practical applications. In contrast to traditional error estimators, which work only on an algorithm-by-algorithm basis, the proposed error estimator is universal. They work for the entire class of implicit/explicit/semi-implicit linear multi-step methods that are second-order time accurate. Based on the accurately estimated local error, balance amongst stability, accuracy and efficiency can be well achieved in the dynamic simulation.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 35 no. 2
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 31 July 2024

Shenglei Wu, Jianhui Liu, Yazhou Wang, Jumei Lu and Ziyang Zhang

Sufficient sample data are the necessary condition to ensure high reliability; however, there are relatively poor fatigue test data in the engineering, which affects fatigue…

111

Abstract

Purpose

Sufficient sample data are the necessary condition to ensure high reliability; however, there are relatively poor fatigue test data in the engineering, which affects fatigue life's prediction accuracy. Based on this, this research intends to analyze the fatigue data with small sample characteristics, and then realize the life assessment under different stress levels.

Design/methodology/approach

Firstly, the Bootstrap method and the principle of fatigue life percentile consistency are used to realize sample aggregation and information fusion. Secondly, the classical outlier detection algorithm (DBSCAN) is used to check the sample data. Then, based on the stress field intensity method, the influence of the non-uniform stress field near the notch root on the fatigue life is analyzed, and the calculation methods of the fatigue damage zone radius and the weighting function are revised. Finally, combined with Weibull distribution, a framework for assessing multiaxial low-cycle fatigue life has been developed.

Findings

The experimental data of Q355(D) material verified the model and compared it with the Yao’s stress field intensity method. The results show that the predictions of the model put forward in this research are all located within the double dispersion zone, with better prediction accuracies than the Yao’s stress field intensity method.

Originality/value

Aiming at the fatigue test data with small sample characteristics, this research has presented a new method of notch fatigue analysis based on the stress field intensity method, which is combined with the Weibull distribution to construct a low-cycle fatigue life analysis framework, to promote the development of multiaxial fatigue from experimental studies to practical engineering applications.

Details

International Journal of Structural Integrity, vol. 15 no. 5
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 3 June 2019

Yazhou Wang, Guoliang Qin, Ximeng Ye and Zhenzhong Bao

The purpose of this paper is to develop a numerical framework based on the accurate spectral element method (SEM) to simulate the mixed convective heat transfer within a porous…

97

Abstract

Purpose

The purpose of this paper is to develop a numerical framework based on the accurate spectral element method (SEM) to simulate the mixed convective heat transfer within a porous enclosure with three adiabatic thin baffles of different lengths in nine cases and analyze the effects of several parameters.

Design/methodology/approach

The authors develop an improved time-splitting method to solve the Darcy–Brinkman–Forchheimer model. No extra assumptions are introduced for the intermediate velocity, and the final velocity field satisfies the incompressible constraint strictly compared with the classical method. The governing equations are split into a pure convection problem, a Stokes problem and a thermal diffusion problem. The least-squares variation is adopted for the Stokes problem, and the Galerkin variation is used for the other two problems, such that the pressure and velocity can be discretized with the same interpolation order, which benefits the numerical accuracy and program design.

Findings

Regarding the method, the excellent spectral accuracy, the capability of discretizing complex computational regions and the improved time-splitting methods make SEM an effective tool to accurately predict the non-Darcy convective heat transfer; as for the numerical tests, it is observed that weakened convection and heat transfer are induced by the increasing length of the baffles. The flow and heat transfer in channel 1 is only related to the length of baffle 1 because of the downward-driven right sidewall, and it is more difficult for baffle 3 to form the secondary flow on its tip.

Originality/value

A novel numerical framework for Darcy–Brinkman–Forchheimer model is developed, expanding the application of SEM for simulating non-Darcy convective heat transfer to improve the numerical accuracy. Numerical results and analysis for flow and heat fields could help designers understand the control of heat transfer using adiabatic baffles better.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 9
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 1 May 2005

Guangwen Zhou, Yazhou Jia, Haibo Zhang and Guiping Wang

This paper is to present a new failure model that can be applied to single‐sample failure data of a single system under testing.

608

Abstract

Purpose

This paper is to present a new failure model that can be applied to single‐sample failure data of a single system under testing.

Design/methodology/approach

The Bayesian method is used for the reliability evaluation. The weighted least squares method is used for determining the parameters of the reliability function.

Findings

The authors have observed the operation of a special computer numerical control (CNC) system for a period of over two years, and maintained a reliability database will all the collected failure data, from which the main source of failures can be identified.

Research limitations/implications

Preliminary research results are very encouraging. However, more work will be necessary to validate the new failure model.

Practical implications

The determination of the parameters of the reliability function of a system under testing helps to identify its failure characteristics and potential quality problems.

Originality/value

It is hoped that the paper can help understand some of the challenges in modeling the failure behavior of special CNC systems.

Details

International Journal of Quality & Reliability Management, vol. 22 no. 4
Type: Research Article
ISSN: 0265-671X

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Article
Publication date: 5 December 2024

Zhitian Zhang, Hongdong Zhao, Yazhou Zhao, Dan Chen, Ke Zhang and Yanqi Li

In autonomous driving, the inherent sparsity of point clouds often limits the performance of object detection, while existing multimodal architectures struggle to meet the…

23

Abstract

Purpose

In autonomous driving, the inherent sparsity of point clouds often limits the performance of object detection, while existing multimodal architectures struggle to meet the real-time requirements for 3D object detection. Therefore, the main purpose of this paper is to significantly enhance the detection performance of objects, especially the recognition capability for small-sized objects and to address the issue of slow inference speed. This will improve the safety of autonomous driving systems and provide feasibility for devices with limited computing power to achieve autonomous driving.

Design/methodology/approach

BRTPillar first adopts an element-based method to fuse image and point cloud features. Secondly, a local-global feature interaction method based on an efficient additive attention mechanism was designed to extract multi-scale contextual information. Finally, an enhanced multi-scale feature fusion method was proposed by introducing adaptive spatial and channel interaction attention mechanisms, thereby improving the learning of fine-grained features.

Findings

Extensive experiments were conducted on the KITTI dataset. The results showed that compared with the benchmark model, the accuracy of cars, pedestrians and cyclists on the 3D object box improved by 3.05, 9.01 and 22.65%, respectively; the accuracy in the bird’s-eye view has increased by 2.98, 10.77 and 21.14%, respectively. Meanwhile, the running speed of BRTPillar can reach 40.27 Hz, meeting the real-time detection needs of autonomous driving.

Originality/value

This paper proposes a boosting multimodal real-time 3D object detection method called BRTPillar, which achieves accurate location in many scenarios, especially for complex scenes with many small objects, while also achieving real-time inference speed.

Details

International Journal of Intelligent Computing and Cybernetics, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1756-378X

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Article
Publication date: 21 October 2019

Mohd Rosli Mohamad and Normayuni Mat Zin

This paper aims to discuss the mediating effects of innovation on the relationship between knowledge management and firm competitiveness.

735

Abstract

Purpose

This paper aims to discuss the mediating effects of innovation on the relationship between knowledge management and firm competitiveness.

Design/methodology/approach

A self-administered questionnaire was used to collect data from small construction firms in the Eastern Region of Peninsular Malaysia. Out of the 190 construction firms surveyed, 153 (80.5%) respondents returned their completed questionnaire. These were used for data analysis. The data were then analyzed using the covariance-based structural equation modeling (SEM).

Findings

Knowledge management had a direct and significant positive effect on firm competitiveness. Nonetheless, the effect of knowledge management on firm competitiveness was mediated by innovation. This indicates that knowledge management should be supported by technical and administrative innovations in the firm.

Research limitations/implications

The data collected were from a limited sample of construction firms. In addition, conducting a study on a region of Malaysia may limit the generalizability of the model.

Practical implications

While knowledge management is crucial for a firm’s competitiveness, technical and administrative innovations must be concurrently improved for a stronger firm competitiveness. This is especially true in terms of financial strength and core competence.

Originality/value

This paper provides some empirical evidence that technical and administrative innovations fully mediated the relationship between knowledge management and firm competitiveness. The results consolidate the resource-based view on the importance of internal resource and capability of the firm and improve KM research area. It also strengthens the view that KM is a critical factor for firm competitiveness, but a good KM without strong innovation will not increase the competitiveness of small construction firms.

Details

Competitiveness Review: An International Business Journal , vol. 29 no. 5
Type: Research Article
ISSN: 1059-5422

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Article
Publication date: 16 December 2024

Richard C. Hoffman and Frank Shipper

The purpose of this teaching case is to introduce students to an alternative business model as practiced by the Haier Group, a Chinese company, and how that model was used to turn…

10

Abstract

Purpose

The purpose of this teaching case is to introduce students to an alternative business model as practiced by the Haier Group, a Chinese company, and how that model was used to turn around an acquired company in the United States of America (USA). The explicit teaching objectives are threefold. First, the case provides insights into Haier’s unique employee-centered culture. Second, Haier’s efforts to transfer parts of its culture to the newly acquired General Electric (GE) Appliance Division are discussed. Third, to improve the performance of the acquired division, Haier had to invest in people, equipment and new product technology.

Design/methodology/approach

This case is based on both primary and secondary research. The authors interviewed the chief executive officer. In addition, one of the authors spent a week in China observing and participating in meetings at the Haier Group. Both before and after the interviews, the authors searched both print and electronic media for additional information.

Findings

The case describes how Haier, a large Chinese appliance manufacturer, learned from its own difficult growth in building an employee- and client-driven organization. Haier was able to transfer key aspects of its culture, management practices and technology to help turnaround the well-known American appliance brand GE. The results of the first five years have been financially successful and investment in new product technology (Smart Home) bodes well for the future.

Research limitations/implications

This case represents only one successful turnaround of one acquisition, GE Appliances, by the Haier Group in the USA. Whether the changes introduced would work with other acquisitions in other countries is unknown. Thus, additional follow-up research needs to be done.

Practical implications

This case brings into question the traditional, hierarchical, bureaucratic, spreadsheet-driven model of management that is the predominant model taught and practiced in the USA. Others, such as Gary Hamel and Michele Zanini, have also raised the same question. This case introduces readers to another way and is just one more example of how managers who practice a high engagement style and share financial success with workers can outperform those who do not.

Social implications

This case documents the introduction of nontraditional management and human resource management practices by a foreign, Chinese company, into what at one time had been a highly regarded division of a traditional major American corporation. GE had become known for strident labor-management relationships. The employees’ acceptance of the alternative approach to management was in doubt prior to the acquisition, but over the past five years, the labor–management relationship appears to have improved as well as the profitability of the division.

Originality/value

Although the acquisition of the GE Appliance Division by the Haier Group has been widely reported in the press, knowledge of how the acquisition was successfully turned around from a money-losing GE Division to a profitable and growing portion of the Haier Group has been largely ignored in both the popular press and in instructional material for the classroom. This case study seeks to ameliorate the latter deficiency.

Details

Journal of Participation and Employee Ownership, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2514-7641

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Article
Publication date: 5 March 2018

Haiying Liu, Xin Jiang, Yazhou Yue and Guangen Gao

The study aims to propose reverse processing solution to improve the performance of strapdown inertial navigation system (SINS) initial alignment and SINS-/global positioning…

271

Abstract

Purpose

The study aims to propose reverse processing solution to improve the performance of strapdown inertial navigation system (SINS) initial alignment and SINS-/global positioning system- (GPS) integrated navigation. The proposed scheme can be well applied in the fields of aircraft and aerospace navigation.

Design/methodology/approach

For the SINS alignment phase, a fast initial alignment scheme is proposed: the initial value of reverse filter is determined by the final result of forward filter, and then, the reverse filter is carried out using the stored data. Multiple iterations are performed until the accuracy is satisfied. For the SINS-/GPS-integrated phase, a forward–reverse navigation algorithm is proposed: first, the standard forward filter is used, and then, the reverse filter is carried out using the initial value determined by the forward filter, and the final fusion results are achieved by the weighted smoothing of the forward and reverse filtering results.

Findings

The simulation and the actual test results show that in the initial alignment stage, the proposed reverse processing method can obviously shorten the SINS alignment time and improve the alignment accuracy. In the SINS-/GPS-integrated navigation data fusion stage, the proposed forward–reverse data fusion processing can, obviously, improve the performance of the navigation solution.

Practical implications

The proposed reverse processing technology has an important application in improving the accuracy of navigation and evaluating the performance of real-time navigation. The proposed scheme can be not only used for SINS-/GPS-integrated system but also applied to other integrated systems for general aviation aircraft.

Originality/value

Compared with the common forward filtering algorithm, the proposed reverse scheme can not only shorten alignment time and improve alignment accuracy but also improve the performance of the integrated navigation.

Details

Aircraft Engineering and Aerospace Technology, vol. 90 no. 2
Type: Research Article
ISSN: 1748-8842

Keywords

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