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The purpose of this paper is to investigate the structural, electronic and optical properties of pure zinc oxide (ZnO) and transition metal (Tm)-doped ZnO using Tm elements from silver (Ag) and copper (Cu) by a first-principles study based on density functional theory (DFT) as implemented in the pseudo-potential plane wave in CASTEP computer code.

The calculations based on the generalized gradient approximation for Perdew-Burke-Ernzerhof for solids with Hubbard U (GGA-PBEsol+U) were performed by applying Hubbard corrections U_d = 5 eV for Zn 3d state, U_p = 9 eV for O 2p state, U_d = 6 eV for Ag 4d state and U_d = 9.5 eV for Cu 3d state. The crystal structure used in this calculation was hexagonal wurtzite ZnO with a space group of P63mc and supercell 2 × 2 × 2.

The total energy was calculated to determine the best position for Ag and Cu dopants. The band structures and density of states show that Tm-doped ZnO has a lower bandgaps value than pure ZnO because of impurity energy levels from Ag 4d and Cu 3d states. In addition, Ag-doped ZnO exhibits a remarkable enhancement in visible light absorption over pure ZnO and Cu-doped ZnO because of its lower energy region and extended wavelength spectrum.

The results of this paper are important for the basic understanding of the 3d and 4d Tm doping effect ZnO and have a wide range of applications in designing high-efficiency energy harvesting solar cells.

Presents a technique for diagrammatically representing the operation of portfolio optimization analysis models.

This article attempts to explore the theoretical model and structural dimensions of sustainable consumer behaviour to develop a “sustainable consumer behaviour scale” for sustainable electronic products. Further, this study has tried to elaborate sustainable consumer behaviour by considering the complete consumption cycle which includes purchase, usage and disposal of the sustainable electronic products.

The theory of planned behaviour (TPB) has been employed to understand the multidimensional nature of sustainable consumer behaviour with the help of qualitative and quantitative methods. With the help of a pilot study followed by a main study, a sustainable consumer behaviour scale for sustainable electronic products has been tested and validated for its factor study, reliability, validity and model fit, etc. Moreover, the influence of demographic variables has also been examined with the help of multi-group analysis.

This study highlights that the perceived control behaviour and subjective norms are the major factors that influence sustainable consumer behaviour. Moreover, the results also indicate that female consumers, mid income consumers, young consumers (age below 30) and consumers who have studied up to senior secondary level are more sustainable.

The results can be used by policymakers and managers to identify and target particular subjective norms and factors impacting perceived control behaviour along with a specific set of demographics to increase sustainability amongst consumers and businesses. The results of the current study can help in increasing the focus of the academic research towards sustainable consumer behaviour. It will also encourage firms to include sustainable electronic products in their product line.

To the best of authors' knowledge, the current article is the first empirical study to develop a sustainable consumer behaviour scale by including all the different stages of the consumption cycle using TPB for sustainable electronic products. Although multiple efforts have been made by researchers to analyse sustainable consumer behaviour, there is a scarcity in literature in which research has been done to analyse sustainable consumer behaviour by considering the whole consumption cycle (purchase, usage and disposal).

The purpose of this paper is to provide comprehensive information on preventive maintenance (PM) planning and methods used in the industry in order to achieve an effective maintenance system.

The literature review is organized in a way that provides the general overview of the researches done in the PM. This paper discusses the literatures that had been reviewed on four main topics, which are the holistic view of maintenance policies, PM planning, PM planning concept and PM planning-based in developing optimal planning in executing PM actions.

PM policy is one of the original proactive techniques that has been used since the start of researches on maintenance system. Review of the methods presented in this paper shows that most researches analyse effectiveness using artificial intelligence, simulation, mathematical formulation, matrix formation, critical analysis and multi-criteria method. While in practice, PM activities were either planned based on cost, time or failure. Research trends on planning and methods for PM show that the variation of approaches used over the year from early 1990s until today.

Research about PM is known to be extensively conducted and majority of companies applied the policy in their production line. However, most analysis and method suggested in published literatures were done based on mathematical computation rather than focussing on solution to real problems in the industry. This normally would lead to the problems in understanding by the practitioner. Therefore, this paper presented researches on PM planning and suggested on the methods that are practical, simple and effective for application in the real industry.

The originality of this paper comes from its detail analysis of PM planning in term of its research focus and also direction for application. Extensive reviews on the methods adopted in relation to PM planning based on the planning-based such as cost-based, time-based and failure-based were also provided.

This paper reviews the literature on maintenance strategies for energy efficiency as a potential maintenance approach. The purpose of this paper is to identify the main concept and common principle for each maintenance strategy for energy efficiency.

A literature review has been carried out on maintenance and energy efficiency. The paper systematically classified the literature into three maintenance strategies (e.g. inspection-based maintenance [IBM], time-based maintenance [TBM] and condition-based maintenance [CBM]). The concept and principle of each maintenance strategy are identified, compared and discussed.

Each maintenance strategy's main concept and principle are identified based on the following criteria: data required and collection, data analysis/modeling and decision-making. IBM relies on human senses and common senses to detect energy faults. Any detected energy losses are quantified to energy cost. A payback period analysis is commonly used to justify corrective actions. On the other hand, CBM monitors relevant parameters that indicate energy performance indicators (EnPIs). Data analysis or deterioration modeling is needed to identify energy degradation. For the diagnostics approach, the energy degradation is compared with the threshold to justify corrective maintenance. The prognostics approach estimates when energy degradation reaches its threshold; therefore, proper maintenance tasks can be planned. On the other hand, TBM uses historical data from energy monitoring. Data analysis or deterioration modeling is required to identify degradation. Further analysis is performed to find the optimal time to perform a maintenance task. The comparison between housekeeping, IBM and CBM is also discussed and presented.

The literature on the classification of maintenance strategies for energy efficiency has been limited. On the other hand, the ISO 50001 energy management systems standard shows the importance of maintenance for energy efficiency (MFEE). Therefore, to bridge the gap between research and industry, the proposed concept and principle of maintenance strategies will be helpful for practitioners to apply maintenance strategies as energy conservation measures in implementing ISO 50001 standard.

The novelty of this paper is in-depth discussion on the concept and principle of each maintenance strategy (e.g. housekeeping or IBM, TBM and CBM) for energy efficiency. The relevant literature for each maintenance strategy was also summarized. In addition, basic rules for maintenance strategy selection are also proposed.

The purpose of this paper is to examine the relationship between total quality management (TQM), market orientation and service quality in the Malaysian service industry.

Data from 150 service firms were collected. Structural equation modeling was employed in this study to examine the associations between TQM, market orientation and service quality.

This study provides empirical evidence and confirms findings obtained from previous studies that TQM has a positive and significant relationship with both market orientation and service quality. Moreover, it was discovered that market orientation is also significantly related to service quality.

This research study implies that if firms are not able to comprehend the importance of TQM dimensions, by which the different dimensions of it can influence a firm's performance, they may not succeed in harvesting the full value of market orientation and service quality. Meanwhile, the findings may guide the service practitioners to understand the importance of TQM in their managerial actions in enhancing market orientation and service quality, which serves as a sound foundation for building a distinguished point of differentiation in their services.

Past researchers have not looked into the tri‐dimensional relationship between TQM, market orientation and service quality and hence research is to be called for in this area. The paper provides practitioners with useful guidelines on the appropriate TQM practices to be implemented so that market orientation and the quality of service can be enhanced, creating superior value to the customers in a unique way, which subsequently improves a firm's competitiveness.

Service quality has been highlighted as the vital element in fulfilling customers' needs, which contributes to the customers' evaluation on the services given. As food truck business is increasingly popular in Malaysia, it is important for the food trucks' service provider to ensure that their service quality meets the standard to satisfy the customers in order to build customer loyalty. Therefore, the aim of this study is to investigate the relationship between food trucks' service quality with customer satisfaction and its impact toward customer loyalty. The customer service was measured using service quality (SERVQUAL) attributes (tangibles, reliability, responsiveness, assurance and empathy).

A quantitative study was conducted to examine the influence of food trucks' service quality on customer satisfaction and its impact toward customer loyalty. A total of 100 food truck customers have been randomly selected to answer the self-administered questionnaire. Data collected were analyzed using frequency, descriptive, reliability, Pearson correlation and regression analysis.

Findings indicated that three out of five attributes of service quality have significant relationships toward customer satisfaction. They are tangibles (β = 0.225, p < 0.05), reliability (β = 0.349, p < 0.05) and assurance (β = 0.311, p < 0.05). Moreover, the customer loyalty (β = 0.643, p < 0.01) has a significant relationship with customer satisfaction.

Service quality can be characterized as the discrepancy between customer service standards and actual service. When expectations are higher than performance, perceived quality is less than acceptable and therefore consumer disappointment exists which eventually decreases customer loyalty toward a product or services. The study suggested that physical image of the food trucks' service like physical facilities, how the service being performed and also courtesy and knowledge of the food trucks' employees are very important to transfer confidence and trust to customers, which then will influence them to be loyal.

The purpose of this paper is to examine the relationship between total quality management (TQM) practices and customer satisfaction and also to investigate the association between TQM practices and service quality within the context of Malaysia's small service organizations.

The paper uses data from the perceptions of sales and marketing managers in 108 small service organizations in Malaysia. Data were analyzed by employing correlation and multiple regression analysis to test the relationship between TQM practices, customer satisfaction and service quality.

The results showed that TQM practices are significantly and positively linked to customer satisfaction and service quality of the small service business firms. It was further confirmed that the dimensions of customer focus and information and analysis were strongly linked to customer satisfaction and service quality.

The results of this paper can be used by marketing/sales managers to prioritize the adoption of the dimensions for TQM practices. For instance, those dimensions that are found to have positive influence on customer satisfaction and service quality can be recommended to marketing/sales managers so that they can allocate resources to improve these practices to achieve higher customer satisfaction and quality of service.

This paper identifies two dimensions of TQM namely, customer focus and information and analysis that can influence customer satisfaction and service quality in Malaysia's small service business firms.

This study empirically analyzes the direct impacts of soft quality management practices (SQMP) and market orientation ambidexterity (MOA) on product innovation ambidexterity (PIA). It also examines the mediating role of MOA in the relationship between SQMP and PIA.

Following a quantitative research methodology, a well-structured questionnaire is used to collect data from 130 Moroccan certified ISO 9001 firms. The conceptual framework of the study was tested using partial least squares structural equation modeling.

The results show that SQMP have no significant association with PIA while they positively and significantly impact MOA. The study also revealed that MOA has a positive and significant impact on PIA and fully mediates the relationship between SQMP and PIA.

Due to the conceptualization of MOA and PIA as combined ambidexterity, the results of the study might be different in the case of balanced ambidexterity.

To achieve PIA, managers need to be aware that implementing SQMP, while important, is not enough. They must invest sufficient resources to properly implement these practices to support MOA. Consequently, MOA will lead their organization to PIA by establishing the significant impact of SQMP on PIA.

Regardless of the abundant literature on the relationship between quality management (QM) practices and innovation, this study is among the first to examine the impact of SQMP on PIA. Using MOA as a mediator can give a meaningful answer to the indecisive empirical results of the impact of QM on innovation. Furthermore, this research contributes to the scarce literature on relevant studies conducted in developing countries.

Opportunistic maintenance (OM) policy is a prospective maintenance approach that instigates for a more effective and optimized system. The purpose of this paper is to provide the steps and methods used in model development processes for the application of the OM policy.

Dubbed as opportunistic principle toward optimal maintenance system (OPTOMS) for OM policy toward optimal maintenance system, the model is devised as a decision support system model and contains five phases. The motivation and focus of the model resolve around the need for a practical framework or model of maintenance policy for the application in an industry. In this paper, the OPTOMS model was verified and validated to ensure that the model is applicable in the industry and robust as a support system in decision making for the optimal maintenance system.

From the verification steps conducted in a case study company, it was found that the developed model incorporated simple but practical tools like check sheet, failure mode and effect analysis (FMEA), control chart that has been commonly used in the industry.

This paper provides the general explanations of the developed model and tools used for each phase in implementing OM to achieve an optimal maintenance system. Based on a case study conducted in a semiconductor company, the OPTOMS model can align and prepare the company in increasing machine reliability by reducing machine downtime.

The novelty of this paper is based on the in-depth discussion of all phases and steps in the model that emphasize on how the model will become practical theories in conducting an OM policy in a company. The proposed methods and tools for data collection and analysis are practical and commonly used in the industry. The framework is designed for practical application in the industry. The users would be from the Maintenance and Production Department.