Search results

The purpose of this paper is to establish a stiffness model of fixed joint considering self-affinity and elastoplasticity of asperities.

The proposed model considers that asperities of different scales are interrelated rather than independent. For elastoplastic contact, a spring-damper model and an elastic deformation ratio function were proposed to calculate the contact stiffness of asperities.

A revised fractal asperity model was proposed to calculate the contact stiffness of fixed joint, the impacts of the fractal dimension, the fractal roughness parameter and the Meyer index on the contact stiffness were discussed, and the present experimental results and the Jiang’s experimental results showed that the stiffness can be well predicted by proposed model.

The contradiction between the Majumdar and Bhushan model and the Morag and Etsion model can be well explained by considering the interaction among asperities of different scales. For elastoplastic contact, elastic deformation ratio should be considered, and the stiffness of asperities increases first and then decreases with the increasing of interference.

Planning for underground spaces has become an effective way to use central areas in cities given the steady economic growth in China. The development of underground spaces in mountainous cities has satisfied the needs of the diversification of the city commercial areas and pedestrian movement. Safety issues exist because these underground spaces were originally used for civil air defense. This study was based on the underground commercial street in Chongqing, which is a typical mountainous city. Based on the results of combined fieldwork and survey, this paper summarized current safety issues, which include the not-fully-open exit, the imbalanced exit location, blocked evacuation routes, and the poor awareness of the potential safety issues. This paper proposed a framework of the safety factors for the underground space and synopsized prevention strategies that are specific to potential disasters in the underground environment. The framework comprises ensuring that the exits are fully open, the underground corridors are kept unblocked, the open space on the street is increased for disaster prevention, and equipment security is maintained and managed. At last, This paper summarized disaster prevention strategies, which include ensuring unimpeded exits, balancing the locations of the exits, avoiding blocks, increasing the disaster prevention square area in the underground space, maintaining and managing the security of the equipment.

Product development process (PDP) in the context of Industry 4.0 may present several marketing implications. To understand these implications, the purpose of this study is to identify the benefits and difficulties of Industry 4.0 related to the PDP and its impact in marketing strategies and operations.

The methodology used to perform this research was a systematic literature review. For this, five steps were followed, namely, research question formulation; studies location; studies selection and evaluation; analysis and synthesis; and reporting and use research results.

The systematic literature review considering PDP in Industry 4.0 context resulted in 28 benefits and 14 difficulties, in a total of 53 articles. From the analysis of these benefits and difficulties, several implications for marketing were identified, namely, better understand customer preferences; greater agility in marketing decision-making; better align marketing, product development and operations processes issues; better understand product/service lifecycle; analyze possibilities of new ways of distribution and communication channels; better define the value of products and services and location requirements.

The findings presented here can be used both by market professionals, interested in the subject and by researchers for future studies. The better understanding of PDP in the context of Industry 4.0 can enhance marketing strategies for market professionals and provide insights for researchers. No similar studies were found in the literature.

The purpose of this paper is to propose a new algorithm for in‐mission trajectories and speed adjustment of multiple unmanned aerial vehicles (UAVs) participating in a mission that requires them to arrive at target location simultaneously with switching and imperfect communication among the vehicles.

This algorithm, programmed at each UAV level, is based on the repeated consensus seeking among the participating vehicles about the time‐on‐target (ToT) through an imperfect inter‐vehicle communication link. The vehicles exchange their individual ToT values repeatedly for a particular duration to pick the highest value among all the vehicles in communication. A consensus confidence flag is set high when consensus is successful. After every consensus cycle with high confidence value, the mission adjustment is carried out by computing difference value between ToT consensus and a threshold value. For the difference values higher than a certain limit, vehicle's trajectory is adjusted by in‐mission insertion of new waypoint (WP) and for lower values the vehicle's speed is varied under allowable limits. The consensus seeking followed by the mission adjustment is repeated periodically to quash the imperfect communication effects.

A mathematical analysis has been carried out to establish the conditions for convergence of the algorithm. The simultaneous arrival of the vehicles subjected to switching communication is achieved only when the union of the switching links during the consensus period enables a vehicle to receive information from all the other vehicles and the switching rate is sufficiently high. This algorithm has been tested in a 6‐degree‐of‐freedom (DoF) multiple UAV simulation environment and achieves simultaneous arrival of multiple fixed wing UAVs under imperfect communication links that meets the aforementioned conditions.

The presented algorithm and design strategy can be extended for other types of cooperative control missions where certain variable of interest is shared among all the vehicles over imperfect communication environment. The design is modular in functionality and can be incorporated into existing vehicles or simulations.

This research presents a new consensus algorithm that repeatedly performs polling of ToT among the vehicles through intermittent communication. The continual nature of consensus seeking covers the weakness of the imperfect communication. A two‐level mission adjustment provides better accuracy in simultaneous arrival at the target location.

The purpose of this paper is to propose a method that calibrates the hand-eye relationship for eye-to-hand configuration and afterwards a rectification to improve the accuracy of general calibration.

The hand-eye calibration of eye-to-hand configuration is summarized as a equation AX = XB which is the same as in eye-in-hand calibration. A closed-form solution is derived. To abate the impact of noise, a rectification is conducted after the general calibration.

Simulation and actual experiments confirm that the accuracy of calibration is obviously improved.

Only a calibration plane is required for the hand-eye calibration. Taking the impact of noise into account, a rectification is carried out after the general calibration and, as a result, that the accuracy is obviously improved. The method can be applied in many actual applications.

The purpose of this paper is to understand the current practices of tool and die development, particularly in the Malaysian context with respect to collaborative manufacturing (CM). It is important to gauge the presents of CM, which is one of the key elements of Industrial Revolution 4.0 (IR 4.0) so that significant initiatives could be taken. The findings are also expected to address the issues pertaining limited information related to collaborative tool and die development in Malaysia.

A survey was carried out among the key players in the local tool and die industry, covering issues such as operational structure in practice, internal collaboration, external collaboration and application of collaborative technology.

The results revealed that although practitioners realise that there are systems and available technological support, unfortunately, it has not been embraced due to poor communication, lack of commitment and cooperation from employees and business owners. In addition, industry players also need to be aware of the benefits concerning CM for a sustainable future.

Many industry players are rather reluctant to participate in surveys and tend to reserve their opinions regarding their operational practices. Lack of awareness among the industry players contributed to the poor participation of the survey and based on the feedback, some of the industry players are not well-informed regarding the latest developments in the industry.

The data and feedback gained through the research offer the perspective for the current state of CM particularly the tool and die industry in Malaysia. This may be a preliminary study with limited data but the value of the information is significant for further in-depth study and policy alignment towards enhancing the tool and die industry which is rarely given attention to. Understanding the current state of CM particularly in the tool and die development would be critical for the expansion of IR 4.0 concerning this field in Malaysia.

The purpose of this paper is to examine how different network members utilize and use network‐level performance measurement information. This is an important approach when discussing the management and development of a network by utilizing a performance measurement system.

The study is a single‐case study, where a collaborative network forms the case. The data of the study have been gathered from an action research process of network performance measurement system design and its implementation phase in 2009, interviews in 2010, and discussions with the interviewees in 2012 to re‐evaluate the results.

The results of the study reveal that the use of the network‐level performance measurement system increased communication, trust, and commitment in the whole network, as well as in a single reselling unit. The performance measurement information also helped the companies create better alignment with their network partners.

The paper presents the main uses, utilizations and benefits of network‐level performance measurement and management from the perspectives of the different network members.

The case study contributes to the literature of performance measurement and management in a network environment. It presents the main uses and utilization of network‐level performance management and measurement.

This study proposes the Smart SME Technology Readiness Assessment (SSTRA) methodology which aims to enable practitioners to assess the SMEs Industry 4.0 technology readiness throughout the end-to-end engineering across the entire value chain; the smart product design phase is the focus in this paper.

The proposed SSTRA utilises the analytic hierarchy process to prioritise smart SME requirements, a graphical interface which tracks technologies' benchmarks under Industry 4.0 Technology Readiness Levels (TRLs); a mathematical model used to determine the technology readiness and visual representation to understand the relative readiness of each smart main area. The validity of the SSTRA is confirmed by testing it in a real industrial environment. In addition, the conceptual model for Smart product design development is proposed and validated.

The proposed SSTRA offers decision-makers the facility to identify requirements and rank them to reflect the current priorities of the enterprise. It allows SMEs to assess their current capabilities in a range of technologies of high relevance to the Industry 4.0 area. The SSTRA assembles a readiness profile allowing decision-makers to not only perceive the overall score of technology readiness but also the distribution of technology readiness across the main smart areas. It helps to visualise strengths and weaknesses; whilst emphasising the fundamental gaps that require serious action to assist the program with a well-balanced effort towards a successful transition to Industry 4.0.

The SSTRA provides a step-by-step approach for decision-making based on data collection, analysis, visualisation and documentation. Hence, it greatly mitigates the risk of further Industry 4.0 technology investment and implementation.

The purpose of this paper is to examine how a performance measurement system (PMS) can be designed for a collaborative network and to identify which factors affect such a design.

This is a single-case study of a collaborative network. The data have been collected from semi-structured interviews conducted during 2008-2009 and after the design process in 2010 and 2012, respectively.

The research results present a five-step process model for designing a PMS for a collaborative network. The findings show that a participatory development style that enhances socialisation, the positive development of a network culture and an outside facilitator all have beneficial effects on the design process.

The practical contribution of this study is related to knowledge about the PMS design process for a collaborative network to support its measurement-related development projects. This knowledge involves the phases of such a process as well as the various factors supporting or hindering it.

The study presents a PMS design process for the case network, which can be utilised in other collaborative networks in a similar context. It also highlights the most essential practical experiences related to this process.