Search results

1 – 10 of 32
Article
Publication date: 4 May 2012

Guangbin Tan, Ping Yang, Tianbo Li, Tao Xi, Xiaoming Yuan and Jianming Yang

The purpose of this paper is to provide a systematic method to perform analysis and test for vibration‐thermal strain behavior of plastic ball grid array (PBGA) assembly by…

Abstract

Purpose

The purpose of this paper is to provide a systematic method to perform analysis and test for vibration‐thermal strain behavior of plastic ball grid array (PBGA) assembly by considering thermal and vibration loading mode. Also to investigate the dynamic behavior of PBGA assembly by considering loading modes for design and reliability evaluation of PBGA packaging.

Design/methodology/approach

A PBGA assembly prototype with different structure and material parameters is designed and manufactured. Based on investigation of the structural and physical parameters of PBGA sample, the vibration‐thermal strain test is developed to measure the strain distribution at the surface of the BT (bismaleimide triazine) substrates and PCB (printed circuit board) surface under vibration‐thermal cycling loading such as random vibration and the temperature is changed from 0°C to 100°C.

Findings

The test results show that the loading modes have different impact on PCB, EMC and substrate, respectively. In the meantime, it is shown that the characteristics of the compound mode is not the linear accumulative result by single vibration mode and single thermal loading mode as forecasted. The nonlinear mechanism for these modes application is the future work for progress.

Research limitations/implications

It is very difficult to set up a numerical approach to illustrate the validity of the testing approach because the complex loading modes and the complex structure of PBGA assembly. The research on an accurate mathematical model of the PBGA assembly prototype is a future work.

Practical implications

It implies a potential design characteristic for future application of PBGA assembly. It also builds a basis for future work for design and reliability evaluation of BGA package.

Originality/value

This paper fulfils useful information about the thermal‐vibration coupling dynamic behavior of PBGA assembly with different structure characteristics, materials parameters.

Article
Publication date: 29 April 2014

Ping Yang, Xiusheng Tang, Yu Liu, Shuting Wang and Jianming Yang

The purpose of this paper is to perform experimental tests on fatigue characteristics of chip scale package (CSP) assembly under vibration. Some suggestions for design to prolong…

Abstract

Purpose

The purpose of this paper is to perform experimental tests on fatigue characteristics of chip scale package (CSP) assembly under vibration. Some suggestions for design to prolong fatigue life of CSP assembly are provided.

Design/methodology/approach

The CSP assembly which contains different package structure modes and chip positions was manufactured. The fatigue characteristics of CSP assembly under vibration were tested. The fatigue load spectrum of CSP assembly was developed under different excitation. The fatigue life of chips can be estimated by using the high-cycle fatigue life formula based on different stress conditions. The signal–noise curve shows the relationship between fatigue life and key factors. The design strategy for improving the fatigue life of CSP assembly was discussed.

Findings

The CSP chip has longer fatigue life than the ball grid array chip under high cyclic strain. The closer to fixed point the CSP chip, the longer fatigue life chips will have. The chip at the edge of the printed circuit board (PCB) has longer fatigue life than the one in the middle of the PCB. The greater the excitation imposed on the assembly, the shorter the fatigue life of chip.

Research limitations/implications

It is very difficult to set up a numerical approach to illustrate the validity of the testing approach because of the complex loading modes and the complex structure of CSP assembly. The research on an accurate mathematical model of the CSP assembly prototype is a future work.

Practical implications

It builds a basis for high reliability design of high-density CSP assembly for engineering application. In addition, vibration fatigue life prediction method of chip-corner solder balls is deduced based on three-band technology and cumulative damage theory under random vibration so as to verify the accuracy of experimental data.

Originality/value

This paper fulfils useful information about the dynamic reliability of CSP assembly with different structural characteristics and material parameters.

Details

Microelectronics International, vol. 31 no. 2
Type: Research Article
ISSN: 1356-5362

Keywords

Article
Publication date: 2 January 2018

Dong Yang, Zhenxiang Liu, Ting Shu, Lijia Yang, Jianming Ouyang and Shen Zhi

Helical coil electromagnetic launchers (HEMLs) using motion-induced commutation strategy solve the problem of synchronization control perfectly. HEMLs can meet the requirements of…

Abstract

Purpose

Helical coil electromagnetic launchers (HEMLs) using motion-induced commutation strategy solve the problem of synchronization control perfectly. HEMLs can meet the requirements of multiple applications such as the electromagnetic catapult, electromagnetic mortar and high-velocity coilgun. The trade-off between the velocity and efficiency is an important basis for these different applications. To optimize such objectives before actual design, the purpose of this paper is to focus on the efficient and flexible calculation model and algorithm. A novel structure of HEML is proposed after the transient simulation by this algorithm, which can improve the energy conversion efficiency and suppress the muzzle arc without affecting the velocity too much.

Design/methodology/approach

The equivalent circuit model of the launcher is established and the governing equations are derived. A combination of the four-stage Runge–Kutta method and the trapezoidal quadrature formula are used to solve the governing equations.

Findings

With smaller number of turns in the coils of HEML, the velocity is larger and the efficiency is lower. The non-uniform HEML is an effective option to improve the energy conversion efficiency and to suppress the muzzle arc with almost the same muzzle velocity as the conventional HEML.

Originality/value

The paper presents a common model and a flexible fast numerical method which can be used in multi-objective optimization of HEMLs such as the genetic algorithm. A new structure of the non-uniform HEML is proposed to improve the energy conversion efficiency and to suppress the muzzle arc of the launcher.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 37 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 6 October 2021

Ying Pan, Lia H. Sun, Heqing Yang and Jianming Zheng

“Library + cultural tourism” (LCT) is a new direction for the sustainable development of libraries, but few scholars have researched it from a tourist perspective. The purpose of…

Abstract

Purpose

“Library + cultural tourism” (LCT) is a new direction for the sustainable development of libraries, but few scholars have researched it from a tourist perspective. The purpose of this paper is to identify what factors affect tourist satisfaction (TS) with LCT, reveal the interaction among these factors and provide strategies for better library services.

Design/methodology/approach

This study collected 5,308 comments on Tianjin Binhai Library from three popular online travel communities. Grounded theory was adopted to identify what factors affect TS with LCT and reveal the interaction among these factors.

Findings

The results indicated that TS with LCT was affected by complex factors related to tour plans, tour expectations, cultural characteristics, environment, support services and emotions. Cultural characteristics, environment and support services were impacted by tour plans and tour expectations, which directly or indirectly affected TS mediated by emotions. TS further influenced their expectation of their next tour.

Originality/value

This paper uncovered critical problems with LCT using a case study of Tianjin Binhai Library. The results provide a reference for library practitioners to develop better library services for tourists and regular users/readers.

Article
Publication date: 29 January 2020

Zhe Cheng, Yongjian Ke, Zhenshan Yang, Jianming Cai and Huanming Wang

As an innovation model for infrastructure and public service delivery, public–private partnership (PPP) has been widely adopted around the world. The knowledge spillover effect…

1016

Abstract

Purpose

As an innovation model for infrastructure and public service delivery, public–private partnership (PPP) has been widely adopted around the world. The knowledge spillover effect and policy diffusion mechanism have played an important role in promoting the development of PPP in the context of globalization. A comparative evaluation of the policy and management of PPP in different countries will help to understand the development of PPP, provide decision-making reference for PPP policy embedded with specific national conditions of each country, and also contribute to the global PPP knowledge body.

Design/methodology/approach

Based on the principle of comparability and representativeness, this study selected three countries, namely, China, India, and the United Kingdom for comparative analysis. This study first introduced the policy process and key institutions of PPP in three countries. Secondly, a comparative analysis of the development characteristics and application of PPP was conducted based on the official database of three countries. Finally, the differences, influencing factors and development trends of international PPP development were analyzed based on the comparative research results, and suggestions for PPP policy and management were put forward.

Findings

The research results indicate the development fluctuation and unbalanced spatial distribution of PPPs are a common phenomenon in the three countries. The UK has a significant impact on the policy and development of PPP in other countries. However, under the combined influence of factors such as economic, urbanization, political regime and social culture, there are significant differences in the PPP institution, application, and project characteristics in various countries. Due to international exchanges and knowledge spillovers, as well as the promotion of intermediaries, the development of PPP worldwide tends to converge.

Practical implications

Through conducting an international comparison of PPPs based on project data, this study provides a detailed and visualized overview of PPPs and a better understanding of PPP policy and management in different countries. The findings will be of interest to PPP investors, officers, practitioners, policymakers, researchers, and analysts. It enriches the portrait of global PPP market research, helps governments to improve the design of PPP institutions and policies, and provides references for decision-making of international investors when stepping into a new market.

Originality/value

This study is the first attempt to systematically compare and analyze the global PPP difference and development trend based on PPP project databases of different countries. Different from previous PPP comparative research based on perception data, the project data-based comparative analysis in this study is helpful to understand the characteristics, interrelations, and trends of global PPP development and enrich the existing PPP knowledge body. This study also proposes that it is possible to establish a global PPP knowledge community in the context of globalization and global production network.

Details

Engineering, Construction and Architectural Management, vol. 27 no. 6
Type: Research Article
ISSN: 0969-9988

Keywords

Article
Publication date: 1 June 2009

Zhang Feifei, Cai Jianming and Liu Gang

In Beijing, urban agriculture (UA) experienced a corkscrew development with its role changing in decades: It has evolved from the purely production mode to multi-functional urban…

Abstract

In Beijing, urban agriculture (UA) experienced a corkscrew development with its role changing in decades: It has evolved from the purely production mode to multi-functional urban agriculture, fulfilling both social and ecological demands. At present, the practice of UA as well as the number of rural to urban migrants is growing rapidly in peri-urban Beijing. Through Multi-stakeholder Process for Action planning and Policy Design (MPAP) methodology and four in-depth case studies, we can see that UA activities are playing very important roles in reshaping peri-urban Beijing. Socially, UA induces the emergence of new migrant communities. While migrants rebuild their social network, they are changed by the city as well, which has also changed the local community. The new comers are on their way to creating a new balance. Physically, urban and peri-urban farmland limits urban sprawl, supplies agricultural products for everyday life, and reserves urban green spaces for recreation and leisure for citizens in Beijing, which has changed the landscape and land use and land cover (LUCC) pattern greatly. Under Beijing's land policy, the concentric configuration spatial allocation through multi-functional UA is formed, which at the same time due to migrants' UA activities are creating harmful and low efficient land use pattern which should be of concern.

Details

Open House International, vol. 34 no. 2
Type: Research Article
ISSN: 0168-2601

Keywords

Article
Publication date: 26 January 2021

Van Thac Dang, Ninh Nguyen and Jianming Wang

A review of 67 articles in the indoor environmental quality (IEQ) literature published from 2010 to 2020 reveals that none of prior studies have determined the IEQ of physical…

2152

Abstract

Purpose

A review of 67 articles in the indoor environmental quality (IEQ) literature published from 2010 to 2020 reveals that none of prior studies have determined the IEQ of physical retailers and its impact on consumers. To fill such a gap, this study investigates the influence of physical retailers' IEQ on consumer purchase intention. The mediating roles of hedonic experience and perceived brand value (PBV) in this relationship are also determined. Furthermore, the moderating effect of perceived service quality (PSQ) on the link between physical retailers' IEQ and PBV is clarified in this study.

Design/methodology/approach

This study uses structural equation modeling (SEM) to analyze a sample data of 996 consumers in China.

Findings

Results show that physical retailers' IEQ has a positive impact on consumer purchase intention. Hedonic experience mediates the link between IEQ and purchase intention. PBV also mediates the relationship between IEQ and purchase intention and that between hedonic experience and purchase intention. In addition, PSQ moderates the relationship between IEQ and PBV.

Originality/value

To the best of the authors’ knowledge, this study is the first to determine the impact of IEQ on consumers in the physical retailer context. Specifically, this study enriches our knowledge about the relationship between physical retailers' IEQ and consumer purchase intention with the mediating and moderating mechanisms of hedonic experience, PBV and PSQ. The findings fill the research gaps in the IEQ literature that has ignored the impact of IEQ on consumers' perception and behavioral intention in the physical retailer context. Furthermore, this research provides evidence for retailer managers to understand and improve physical stores' IEQ.

Details

International Journal of Retail & Distribution Management, vol. 49 no. 6
Type: Research Article
ISSN: 0959-0552

Keywords

Article
Publication date: 14 July 2020

Muhammad Rafi, Khurshid Ahmad, Salman Bin Naeem, Asad Ullah Khan and Zheng JianMing

Digital libraries promote and accelerate scientific research in academic institutions. The subscribed database resources of digital libraries have become an increasingly valuable…

Abstract

Purpose

Digital libraries promote and accelerate scientific research in academic institutions. The subscribed database resources of digital libraries have become an increasingly valuable asset for researchers. Database resources help generate new ideas, determine research directions and promote productive academic interaction between teachers and students in the information age. The purpose of this study is to examine the use of electronic resources by students in various databases, the research productivity of the faculty in the science network and the number of students who graduate each year.

Design/methodology/approach

This study uses a quantitative method to collect secondary data from the central database of the Higher Education Commission (HEC) for the population of 26 universities for 2 years (2015–2016). In addition to the HEC digital library, data was also collected from the Web of Science to determine the quality academic performance of faculty and researchers. Moreover, in the study, the total strength of teaching staff and doctoral faculty was extracted from the HEC website for investigation. The authors applied the Spearman’s correlation test to the secondary data using Statistical Package for Social Sciences version 25.

Findings

The correlation results of the enrolled students and the downloaded papers from various databases were statistically insignificant (p > 0.05). However, the result showed a positive correlation (p < 0.05) between the use of selected/known databases from a number of databases accessed by the HEC. More importantly, it turns out that the faculty’s productivity in the scientific network and the number of students who graduated from public and private universities are found to be insignificant (p > 0.05). However, the authors found a positive correlation (p < 0.05) between doctoral and non-doctoral faculties, which show that a significant number of non-doctoral faculties are still actively involved in teaching and research.

Originality/value

Research based on academic activities by faculties and students, performed for the first time on the basis of secondary data, will help the HEC and university management to determine the right direction and develop plans to improve academic performance and research quality.

Details

The Bottom Line, vol. 33 no. 4
Type: Research Article
ISSN: 0888-045X

Keywords

Article
Publication date: 19 June 2017

Qi Wang, Pengcheng Zhang, Jianming Wang, Qingliang Chen, Zhijie Lian, Xiuyan Li, Yukuan Sun, Xiaojie Duan, Ziqiang Cui, Benyuan Sun and Huaxiang Wang

Electrical impedance tomography (EIT) is a technique for reconstructing the conductivity distribution by injecting currents at the boundary of a subject and measuring the…

Abstract

Purpose

Electrical impedance tomography (EIT) is a technique for reconstructing the conductivity distribution by injecting currents at the boundary of a subject and measuring the resulting changes in voltage. Image reconstruction for EIT is a nonlinear problem. A generalized inverse operator is usually ill-posed and ill-conditioned. Therefore, the solutions for EIT are not unique and highly sensitive to the measurement noise.

Design/methodology/approach

This paper develops a novel image reconstruction algorithm for EIT based on patch-based sparse representation. The sparsifying dictionary optimization and image reconstruction are performed alternately. Two patch-based sparsity, namely, square-patch sparsity and column-patch sparsity, are discussed and compared with the global sparsity.

Findings

Both simulation and experimental results indicate that the patch based sparsity method can improve the quality of image reconstruction and tolerate a relatively high level of noise in the measured voltages.

Originality/value

EIT image is reconstructed based on patch-based sparse representation. Square-patch sparsity and column-patch sparsity are proposed and compared. Sparse dictionary optimization and image reconstruction are performed alternately. The new method tolerates a relatively high level of noise in measured voltages.

Details

Sensor Review, vol. 37 no. 3
Type: Research Article
ISSN: 0260-2288

Keywords

Book part
Publication date: 20 January 2021

Yao Lixia

Abstract

Details

Energy Security in Times of Economic Transition: Lessons from China
Type: Book
ISBN: 978-1-83982-465-4

1 – 10 of 32