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The purpose of this paper is to determine the nature and extent of the current practice of logistics in the construction industry and to investigate the utility of reverse logistics in a construction context.

A pilot study was utilised to devise a method for the identification and measurement of parameters for incorporation within a process of construction site logistics optimisation. Data on vehicular movements were collected from seven sites in Cape Town. The data were used to design a flow model of material delivery and waste removal vehicular movements.

The results showed that in terms of transport distribution, of all vehicle movements observed, 62.6 per cent were classified as material delivery and 26.3 per cent as construction and demolition (C&D) waste removal. This ratio approximates to 2.4 materials delivery journeys to one waste removal journey. An optimised integrated materials delivery and waste removal logistics model is presented.

The research has highlighted the potential for integration of building materials and C&D waste logistics. Based on the ratio of 2.4:1, up to 26.3 per cent of vehicular movements transiting sites could be eliminated by allowing material delivery vehicles to back‐haul waste to points of disposal, reuse or reclamation.

The potential use of “reverse logistics” in a construction context is demonstrated, as is the scope for the utilisation of spare capacity through the application of the reverse logistics concept and the possible reduction in unit costs and numbers of empty vehicular movements.

Materials supply is one of the important elements in construction operation and a major factor affecting the quality of construction projects. Many industries look to manage materials effectively by attempting to integrate logistics processes into logistics chains of suppliers and customers. Logistics processes, being crucial for successful completion of construction projects, but in fact, auxiliary, are often entrusted to external professionals specialised in logistic services, such as logistics centres. However, this tendency is yet to be developed in construction. The purpose of this paper is to develop a simulation framework for the examination of potential improvements of logistics performance using logistics centres.

A case study approach was adopted with computer simulation using Flexsim. Data of vehicle movements were collected during construction on-site from the start of construction to “hand-over” to the building owner.

The ideal location of a logistics centre is identified using vehicle movements data collected on the site. The potential improvements of the planned centre are then evaluated by simulating various scenarios of vehicle movements. The enclosed results from the simulations indicate that using a logistics centre will reduce waste for the construction project considered.

The paper emphasises that creating a logistics centre for a project can improve construction logistics performance, by consolidating and optimizing both off-site and on-site logistics, especially when the site condition is prohibitive (small footprint with limited loading bay area). Establishing logistics centres may help find ways of making the overall construction project more effective by improving the management of materials.

The free roving robot in the form of a computer controlled industrial truck is now technically possible. The use of small on‐board computers and navigation aids frees the robot from dependence on fixed route marking. Conventional vehicles such as fork lift trucks may be modified for autonomous or semi‐autonomous control.

The purpose of this paper is to discuss motion planning about crossing obstacles and welding trajectory for a new-model mobile obstacle-crossing welding robot system. The robot can cross the obstacle in this way that one of the three adhesion mobile parts is pulled off the ground in turn. An optimal obstacle-crossing approach needs to be studied to improve the welding efficiency.

According to the characteristics of this mobile welding robot, two methods for crossing obstacles are compared. A special method is used for obstacle-crossing and welding. The kinematic model is established. By the optimization method, the optimum parameters for crossing obstacles are calculated. The welding speed when the robot is crossing the obstacle is very important, so its value must be in a certain range. Finally, the tracks of the wheels when the robot is crossing the obstacle are analyzed in order to observe the obstacle-crossing process.

According to the analysis, the maximum speed of the vehicle in the obstacle-crossing is determined. When crossing the obstacle, the robot can do welding simultaneously. The welding speed cannot exceed a certain value. In the obstacle-crossing process, the tracks of the wheels can reflect the process. According to the obtained conclusion, the obstacle-crossing experiments are successfully completed, and the welding effect is good. The results can prove that the proposed method is feasible.

The speed of obstacle-crossing is not very large. It has some relationships with the lifting speed of the wheels, which is determined by the quality of drive motor. More efficient robot must be developed to meet the needs of industrial robot.

Based on the excellent obstacle-crossing and welding capabilities, the robot with the new mechanism has a widely applying prospect in the field of welding and inspecting large equipment.

The obstacle-crossing approach has certain innovation. The way that the robot can maintain continuous welding when crossing the obstacle is of a great significance.

Vehicle allocation problems (VAPs), which are frequently confronted in many transportation activities, primarily including but not limited to full truckload freight transportation operations, induce a significant economic impact. Despite the increasing academic attention to the field, literature still fails to match the needs of and opportunities in the growing industrial practices. In particular, the literature can grow upon the ideas on sustainability, Industry 4.0 and collaboration, which shape future practices not only in logistics but also in many other industries. This review has the potential to enhance and accelerate the development of relevant literature that matches the challenges confronted in industrial problems. Furthermore, this review can help to explore the existing methods, algorithms and techniques employed to address this problem, reveal directions and generate inspiration for potential improvements.

This study provides a literature review on VAPs, focusing on quantitative models that incorporate any of the following emerging logistics trends: sustainability, Industry 4.0 and logistics collaboration.

In the literature, sustainability interactions have been limited to environmental externalities (mostly reducing operational-level emissions) and economic considerations; however, emissions generated throughout the supply chain, other environmental externalities such as waste and product deterioration, or the level of stakeholder engagement, etc., are to be monitored in order to achieve overall climate-neutral services to the society. Moreover, even though there are many types of collaboration (such as co-opetition and vertical collaboration) and Industry 4.0 opportunities (such as sharing information and comanaging distribution operations) that could improve vehicle allocation operations, these topics have not yet received sufficient attention from researchers.

The scientific contribution of this study is twofold: (1) This study analyses decision models of each reviewed article in terms of decision variable, constraint and assumption sets, objectives, modeling and solving approaches, the contribution of the article and the way that any of sustainability, Industry 4.0 and collaboration aspects are incorporated into the model. (2) The authors provide a discussion on the gaps in the related literature, particularly focusing on practical opportunities and serving climate-neutrality targets, carried out under four main streams: logistics collaboration possibilities, supply chain risks, smart solutions and various other potential practices. As a result, the review provides several gaps in the literature and/or potential research ideas that can improve the literature and may provide positive industrial impacts, particularly on how logistics collaboration may be further engaged, which supply chain risks are to be incorporated into decision models, and how smart solutions can be employed to cope with uncertainty and improve the effectiveness and efficiency of operations.

Many people feel the automated guided vehicle business is about to take off in the way that robotics did some years ago. John Mortimer reports

The purpose of this study is to develop a holistic optimization model for an integrated sustainable fleet planning and closed-loop supply chain (CLSC) network design problem under uncertainty.

A novel mixed-integer programming model that is able to consider interactions between vehicle fleet planning and CLSC network design problems is first developed. Uncertainties of the product demand and return fractions of the end-of-life products are handled by a chance-constrained stochastic program. Several Pareto optimal solutions are generated for the conflicting sustainability objectives via compromise and fuzzy goal programming (FGP) approaches.

The proposed model is tested on a real-life lead/acid battery recovery system. By using the proposed model, sustainable fleet plans that provide a smaller fleet size, fewer empty vehicle repositions, minimal CO₂ emissions, maximal vehicle safety ratings and minimal injury/illness incidence rate of transport accidents are generated. Furthermore, an environmentally and socially conscious CLSC network with maximal job creation in the less developed regions, minimal lost days resulting from the work's damages during manufacturing/recycling operations and maximal collection/recovery of end-of-life products is also designed.

Unlike the classical network design models, vehicle fleet planning decisions such as fleet sizing/composition, fleet assignment, vehicle inventory control, empty repositioning, etc. are also considered while designing a sustainable CLSC network. In addition to sustainability indicators in the network design, sustainability factors in fleet management are also handled. To the best of the authors' knowledge, there is no similar paper in the literature that proposes such a holistic optimization model for integrated sustainable fleet planning and CLSC network design.

This paper aims to address the longitudinal control problem for person-following robots (PFRs) for the implementation of this technology.

Nine representative car-following models are analyzed from PFRs application and the linear model and optimal velocity model/full velocity difference model are qualified and selected in the PFR control.

A lab PFR with the bar-laser-perception device is developed and tested in the field, and the results indicate that the proposed models perform well in normal person-following scenarios.

This study fills a gap in the research on PRFs longitudinal control and provides a useful and practical reference on PFRs longitudinal control for the related research.

This paper aims to introduce novel linear synchronous motor (LSM) driven assembly automation and material handling system designs with examples.

Discusses novel LSM technology principles with some practical system design and configuration examples for automated assembly and material handling. The high energy density and rugged design offers high duty cycle, high power, rapid acceleration, improved speed, high positioning repeatability, and increased performance for demanding installations.

LSMs can increase throughput, reliability and payload information feedback. They can also decrease maintenance requirements, and the total cost of installation. MagneMotion's patented QuickStick system propels and controls each vehicle independently by interacting with a permanent magnet array mounted to each vehicle. As a consequence, the vehicles do not require communication or power cables, allowing a broad range of flexible, reconfigurable configurations and move profiles.

LSMs can increase throughput, reliability and payload information feedback. They can also decrease maintenance requirements, and the total cost of installation.

Discusses novel LSM technology principles with some practical system design and configuration examples for automated assembly and material handling.