Soo Yong Kim, Minh V. Nguyen and Van Truong Luu
The purpose of this paper is twofold: first, to develop a performance evaluation framework for construction and demolition waste management (CDWM); second, to investigate feasible…
Abstract
Purpose
The purpose of this paper is twofold: first, to develop a performance evaluation framework for construction and demolition waste management (CDWM); second, to investigate feasible and effective strategies to improve the CDWM performance.
Design/methodology/approach
A review of the literature highlighted a lack of comprehensive research to evaluate CDWM performance of key project stakeholders, like owners, contractors and consultants. After the identification of 22 performance variables through a pilot study, a first questionnaire survey was conducted to investigate the views of respondents toward CDWM performance. The 132 responses were analyzed using factor analysis to determine specific CDWM performance factors, which formed a conceptual performance evaluation framework of CDWM. Furthermore, a practical index (PI) was proposed to integrate the feasibility and effectiveness of CDWM strategies. The values of PI were employed to prioritize CDWM strategies from data collected in a second questionnaire survey.
Findings
The validated results from factor analysis revealed that the conceptual performance evaluation framework of CDWM consists of six factors; and the attitude toward CDWM emerged as the foremost critical factor. The prioritization of PI values indicated that raising CDWM awareness among construction stakeholders was the most feasible and effective strategy for CDWM.
Originality/value
This CDWM performance evaluation framework is one of the first to holistically evaluate CDWM from key stakeholder perspectives. In addition, the PI firstly enables quantitative integration of the feasibility and effectiveness of CDWM strategies.
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Soo Yong Kim, Minh V. Nguyen and Tuyen T.N. Dao
This paper aims to propose a comprehensive framework for prioritizing complexity criteria. The framework was validated by applying in infrastructure international development (ID…
Abstract
Purpose
This paper aims to propose a comprehensive framework for prioritizing complexity criteria. The framework was validated by applying in infrastructure international development (ID) project as a case study.
Design/methodology/approach
A literature review highlighted the limitations of existing complexity prioritization methods. Then, a combination of the fuzzy decision-making trial and evaluation laboratory (DEMATEL) and fuzzy analytic network process (ANP) was employed as a foundation to develop a three-stage complexity prioritization framework. Focus group discussion and questionnaire surveys were used to practically test the framework in the infrastructure ID projects.
Findings
The three-stage complexity prioritization framework was validated to be reliable and feasible. The findings showed ability of consultants, scope uncertainties, site compensation and clearance, communication between stakeholders, administrative procedure and project duration were the most significant complexity criteria of ID projects in the Vietnamese context.
Practical implications
The framework is a robust tool that enables the researchers to grasp the interaction of complexity criteria for complexity prioritization. Later studies can apply the proposed framework, with some minor revisions, to assess the interaction of criteria in other research topics in, and beyond, project complexity. Results of the case study suggest project stakeholders focusing on complex interactions among criteria to reduce project complexity.
Originality/value
This study contributes to the body of knowledge by providing a comprehensive complexity prioritization framework that grasps the interrelationship of complexity criteria. For stakeholders of ID projects, the findings provide insightful perspectives to understand complexity, which can help to enhance project performance.
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Miliete Negash Gebremeskel, Soo Yong Kim, Le Dinh Thuc and Minh V. Nguyen
The purpose of this study is to identify driving factors and a quantitative model for implementing public-private partnership (PPP) projects in Ethiopia as a case study in…
Abstract
Purpose
The purpose of this study is to identify driving factors and a quantitative model for implementing public-private partnership (PPP) projects in Ethiopia as a case study in emerging economies.
Design/methodology/approach
A review of the literature and semi-structured interviews were carried out to identify driving factors affecting the implementation of PPP projects in the Ethiopian context. Data were collected through a questionnaire survey within three months, with 59 validated responses; mean score technique and factor analysis were conducted. The fuzzy synthetic evaluation (FSE) method was applied to develop a driving index (DI) for implementing infrastructure PPP projects. Finally, a comparative analysis of top-five drivers was conducted between four emerging economies.
Findings
Mean values show that all driving variables are important. Through factor analysis, 22 identified driving variables were grouped into six factors, namely, benefit for public and private sectors, attention of private sector, social development, cost reduction, management ability of public sector and ability of private sector. The FSE method constructs a DI and shows that benefit for public and private sectors is the most crucial factor for PPP implementation in the context of Ethiopia. Apart from this, most driving forces for adopting PPP projects in these countries related to financial problems.
Originality/value
This study is one of the first integrate driving factors for PPP implementation. The index provides the decision-makers with a comprehensive tool to assess the needs of PPP implementation.
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Xiaolong Lyu, Dan Huang, Liwei Wu and Ding Chen
Parameter estimation in complex engineering structures typically necessitates repeated calculations using simulation models, leading to significant computational costs. This paper…
Abstract
Purpose
Parameter estimation in complex engineering structures typically necessitates repeated calculations using simulation models, leading to significant computational costs. This paper aims to introduce an adaptive multi-output Gaussian process (MOGP) surrogate model for parameter estimation in time-consuming models.
Design/methodology/approach
The MOGP surrogate model is established to replace the computationally expensive finite element method (FEM) analysis during the estimation process. We propose a novel adaptive sampling method for MOGP inspired by the traditional expected improvement (EI) method, aiming to reduce the number of required sample points for building the surrogate model. Two mathematical examples and an application in the back analysis of a concrete arch dam are tested to demonstrate the effectiveness of the proposed method.
Findings
The numerical results show that the proposed method requires a relatively small number of sample points to achieve accurate estimates. The proposed adaptive sampling method combined with the MOGP surrogate model shows an obvious advantage in parameter estimation problems involving expensive-to-evaluate models, particularly those with high-dimensional output.
Originality/value
A novel adaptive sampling method for establishing the MOGP surrogate model is proposed to accelerate the procedure of solving large-scale parameter estimation problems. This modified adaptive sampling method, based on the traditional EI method, is better suited for multi-output problems, making it highly valuable for numerous practical engineering applications.
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Luu Anh Khoa Lanh, Van Tu Duong, Huy Hung Nguyen, Sang Bong Kim and Tan Tien Nguyen
Generally, humanoid robots usually suffer significant impact force when walking or running in a non-predefined environment that could easily damage the actuators due to high…
Abstract
Purpose
Generally, humanoid robots usually suffer significant impact force when walking or running in a non-predefined environment that could easily damage the actuators due to high stiffness. In recent years, the utilization of passive compliant series elastic actuators (SEA) for driving humanoid's joints has proved the capability in many aspects so far. However, despite being widely applied in the biped robot research field, the stable control problem for a humanoid powered by the SEAs, especially in the walking process, is still a challenge. This paper proposes a model reference adaptive control (MRAC) combined with the back-stepping algorithm to deal with the parameter uncertainties in a humanoid's lower limb driven by the SEA system. This is an extension of our previous research (Lanh et al., 2021).
Design/methodology/approach
Firstly, a dynamic model of SEA is obtained. Secondly, since there are unknown and uncertain parameters in the SEA model, a Model Reference Adaptive Controller (MRAC) is employed to guarantee the robust performance of the humanoid's lower limb. Finally, an experiment is carried out to evaluate the effectiveness of the proposed controller and the SEA mechanism.
Findings
This paper proposes an effective control algorithm that can be widely applied for the humanoid-SEA system. Besides, the effect of the coefficients in the control law is analyzed to further improve the response's quality.
Research limitations/implications
Even though the simulation shows good results with stable system response, the practical experiment has not been implemented to fully evaluate the quality of the controller.
Originality/value
The MRAC is applied to control the humanoid's lower limb and the back-stepping process is utilized to combine with an external SEA system but still maintain stabilization. The simplified model of the lower-limb system proposed in the paper is proven to be appropriate and can be taken for further research in the future.
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Hong Thi Bich Nguyen, Norman G. Miller, Nam Khanh Pham and Hiep Thanh Truong
This study aims to investigate countries without national property insurance and see how experience affects behavior toward higher-risk flood prone property.
Abstract
Purpose
This study aims to investigate countries without national property insurance and see how experience affects behavior toward higher-risk flood prone property.
Design/methodology/approach
Using a unique data set that captures the flood experiences of homeowners that search for new housing, the authors examine the premiums or discounts of such experience on homes at risk. The authors use hedonic property modeling to estimate the effects of experience on values.
Findings
The authors find that such experiences play a strong role in convincing buyers of the real risks imposed by climate change and sea level rise and the authors expect these demand-side behavioral changes to persist. This finding is unlike more developed markets where insurance may be subsidized and negative effects on value dissipate within a few years.
Research limitations/implications
The world is starting to pay more attention to climate risk and the results in developed countries have been biased by the extensive insurance provided by the government or emergency funding.
Practical implications
Providing market transparency on climate risks will result in permanent market effects, if not otherwise subsidized.
Social implications
The governments should encourage market disclosure.
Originality/value
No one has ever had a data set like this before where the authors get to observe the behavior of those already experiencing property losses from flooding.
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Phong Dong Nguyen, Nguyen Phong Nguyen, Lam D. Nguyen and Thu Ha Le
This study examines employee emotional exhaustion and turnover intention as the consequences of problematic customer behaviors and tests the role of perceived organizational…
Abstract
Purpose
This study examines employee emotional exhaustion and turnover intention as the consequences of problematic customer behaviors and tests the role of perceived organizational justice and job satisfaction in mitigating these consequences.
Design/methodology/approach
A four-hypothesis model was tested using partial least squares structural equation modeling (PLS-SEM) based on a two-phase survey of 369 frontline services employees in Vietnam with a three-month time lag.
Findings
The study shows that abusive and unreasonably demanding customer behaviors have positive effects on emotional exhaustion, which, in turn, reduces job satisfaction and, subsequently, turnover intention. It also reveals that organizational justice mechanisms attenuate the positive association between emotional exhaustion and turnover intention. Job satisfaction indirectly mitigated the turnover intention of emotionally exhausted employees who had to deal with problematic customer behaviors, especially in the service sector in Vietnam, an emerging market.
Originality/value
Building upon the social exchange theory (SET) and the conservation of resources theory (COR), this study extended the research on organizational justice with respect to emotional exhaustion in the customer service sector that received less attention previously. Rather than merely focusing on the interpersonal factors (e.g. respect and sensitivity) as organizational support does, organizational justice encompasses employees' perception of fairness of outcome and the whole process in an organization to reach decisions.
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Tan Vo-Thanh, Huan Minh Nguyen, Triet Minh Nguyen, Danh Cong Pham and Hung Phuc Nguyen
This study aims to examine the relationships among fear of COVID-19, job stress, job commitment and intention to quit. It also investigates the boundary conditions of the impact…
Abstract
Purpose
This study aims to examine the relationships among fear of COVID-19, job stress, job commitment and intention to quit. It also investigates the boundary conditions of the impact of fear of COVID-19 on job stress and intention to quit, a research gap that has not been addressed yet.
Design/methodology/approach
This research focused on full-time frontline hotel employees who have been working in four- and five-star hotels in Ho Chi Minh City, Vietnam. A pilot test was performed before collecting formal data. The survey was conducted face-to-face on site so that any potential confusion could be clarified right away. 487 valid responses were analyzed using SPSS 28 and SmartPLS 4.
Findings
The majority of hypotheses were supported, with the results suggested that supervisor support contributes to reducing the tendency of hotel employees to quit their job and their job stress. Besides, government support is necessary to make staff feel secure during the pandemic.
Practical implications
This study contributes to pointing out central priorities in making decisions by hotel managers when facing crises. Managers need to focus more on measures to help their employees feel secure and should be available for guidance and feedback when nedeed. Additionally, supportive policies from the government, especially financial support, can provide hotel employees with resources they need to maintain a basic level of living in the face of a severe drop in their income. The study provides the hotel industry not only in Vietnam but also in countries with comparable settings with strategies to cope with unexpected events.
Originality/value
Research on intention to quit a job has mainly focused on a complex interplay of internal factors. However, the influence of fear of COVID-19 on intention to quit a job has not been studied in the context of Vietnamese hotel industry yet. During the COVID-19 pandemic, a number of hotels in Vietnam had to close due to a lack of visitors, which had a negative impact on human resources. Accordingly, fear, stress, commitment and intention to quit a job are the issues faced by staff.
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Tri Duc Tran, Van Tu Duong, Hung Huy Nguyen and Tan Tien Nguyen
Humanoid robots have been utilized in many fields such as medical, construction, and disaster response. While humanoid robots nowadays can achieve great capabilities, the one-leg…
Abstract
Purpose
Humanoid robots have been utilized in many fields such as medical, construction, and disaster response. While humanoid robots nowadays can achieve great capabilities, the one-leg balancing task still poses a challenging problem. This paper aims to propose a novel approach to solve the problem.
Design/methodology/approach
To aid the balance of one leg in humanoid robot, an external balance mechanism is inserted to the back of the humanoid robot. First, a dynamic model of the humanoid robot with balance mechanism and its simplified model are introduced. Second, a backstepping-based control method is utilized to build the proposed controller for one-leg stance system through two steps. For the first step, a minimum observer-based controller with a virtual control input is used to control the first sub-system reaching the desired reference input. For the second step, a virtual control input is considered as a reference input of a second sub-system, then a model reference adaptive controller (MRAC) is employed to control the second sub-system reaching the virtual control input in presence of uncertainties. By using the external balance mechanism, the sideway balancing task is separated from normal walking function. Furthermore, the utilization of the balance mechanism ensures the humanoid robot's hip adduction does not exceed the threshold of a human when walking. Finally, a simulation study is carried out to evaluate the effectiveness of the proposed method.
Findings
This paper proposes a model reference adaptive control using state observer for balancing one leg of humanoid robot in stance phase that extends our previous research (Tran et al., 2021).
Originality/value
The main research contents have been introduced.
Details
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Cong Toai Truong, Kim Hieu Huynh, Van Tu Duong, Huy Hung Nguyen, Le An Pham and Tan Tien Nguyen
In the COVID-19 outbreak periods, people's life has been deranged, leading to disrupt the world. Firstly, the number of deaths is growing and has the potential to surpass the…
Abstract
Purpose
In the COVID-19 outbreak periods, people's life has been deranged, leading to disrupt the world. Firstly, the number of deaths is growing and has the potential to surpass the highest level at any time. Secondly, the pandemic broke many countries' fortified lines of epidemic prevention and gave people a more honest view of its seriousness. Finally, the pandemic has an impact on life, and the economy led to a shortage in medical, including a lack of clinicians, facilities and medical equipment. One of those, a simple ventilator is a necessary piece of medical equipment since it might be useful for a COVID-19 patient's treatment. In some cases, the COVID-19 patients require to be treated by modern ventilators to reduce lung damage. Therefore, the addition of simple ventilators is a necessity to relieve high work pressure on medical bureaucracies. Some low-income countries aim to build a simple ventilator for primary care and palliative care using locally accessible and low-cost components. One of the simple principles for producing airflow is to squeeze an artificial manual breathing unit (AMBU) iterative with grippers, which imitates the motion of human fingers. Unfortunately, the squeezing angle of grippers is not proportional to the exhaust air volume from the AMBU bag. This paper aims to model the AMBU bag by a mathematical equation that enables to implement on a simple controller to operate a bag-valve-mask (BVM) ventilator with high accuracy performance.
Design/methodology/approach
This paper provides a curvature function to estimate the air volume exhausting from the AMBU bag. Since the determination of the curvature function is sophisticated, the coefficients of the curvature function are approximated by a quadratic function through the experimental identification method. To obtain the high accuracy performance, a linear regression model and a least square method are employed to investigate the characteristic of the BVM ventilator's grippers angle with respect to the airflow volume produced by the AMBU bag.
Findings
This paper investigates the correlation between the exhausting airflow of the AMBU bag and the grippers angle of the BVM ventilator.
Originality/value
The experimental results validated that the regression model of the characteristic of the exhausting airflow of the AMBU bag with respect to the grippers' angle has been fitted with a coefficient over 98% within the range of 350–750 ml.