Search results

The use of multiple-capacity rail-guided vehicles (RGVs) has made automated storage and retrieval system (AS/RS) optimization more complex. The paper performs dual-RGV scheduling considering loading/unloading and collision-avoidance constraints simultaneously as these issues have only been considered separately in the previous literature.

This paper proposes a novel model for dual-RGV scheduling with two-sided loading/unloading operations and collision-avoidance constraints. To solve the proposed problem, a hybrid harmony search algorithm (HHSA) is developed. To enhance its performance, a descent-based local search with eight move operators is introduced.

A group of problem instances at different scales are optimized with the proposed algorithm and the results are compared with those of two other high-performance methods. The results demonstrate that the proposed method can efficiently solve realistically sized cases of dual multi-capacity RGV scheduling problems in AS/RSs.

For the first time in the research on dual multi-capacity RGV scheduling in an AS/RS, two-sided loading/unloading operations and collision avoidance constraints are simultaneously considered. Furthermore, a mathematical model for minimizing the makespan is developed and the HHSA is developed to determine solutions.

Optimizing material handling within the factory is one of the key problems of modern assembly line systems. The purpose of this paper is to focus on simultaneously balancing a robotic assembly line and the scheduling of material handling required for the operation of such a system, a topic that has received limited attention in academia. Manufacturing industries focus on full autonomy because of the rapid advancements in different elements of Industry 4.0 such as the internet of things, big data and cloud computing. In smart assembly systems, this autonomy aims at the integration of automated material handling equipment such as automated guided vehicles (AGVs) to robotic assembly line systems to ensure a reliable and flexible production system.

This paper tackles the problem of designing a balanced robotic assembly line and the scheduling of AGVs to feed materials to these lines such that the cycle time and total tardiness of the assembly system are minimized. Because of the combination of two well-known complex problems such as line balancing and material handling and a heuristic- and metaheuristic-based integrated decision approach is proposed.

A detailed computational study demonstrates how an integrated decision approach can serve as an efficient managerial tool in designing/redesigning assembly line systems and support automated transportation infrastructure.

This study is beneficial for production managers in understanding the main decisional steps involved in the designing/redesigning of smart assembly systems and providing guidelines in decision-making. Moreover, this study explores the material distribution scheduling problems in assembly systems, which is not yet comprehensively explored in the literature.

The purpose of this paper is to investigate the mechanical behavior of textile-reinforced concrete (TRC)-strengthened concrete columns with small eccentricity under chloride-wet-dry cycles.

A total of ten reinforced concrete (RC) columns were constructed and subjected to eccentric compression, and the effects of the slenderness ratio, a variable number of wet-dry cycles and the coupled effect of loading and a chloride environment were analyzed. One of the columns tested was unreinforced, whereas the remaining columns were strengthened laterally with TRC.

The results showed that a reduction in the slenderness ratio was conducive to the improvement of the bearing capacity of the reinforced column; however, the reinforcement effect of TRC tended to decrease with an increasing number of wet-dry cycles, and the coupled effect of loading and a chloride environment significantly degraded the compression performance of TRC-strengthened columns, with the damage becoming more serious with increase in the sustained load ratio.

In the next test, the duration of chloride-wet-dry cycles will be extended. In the same time, to obtain a clearer trend, the authors will also increase the number of specimens to obtain more data for drawing general conclusions.

The originality is to explore the feasibility of using cement-based materials (TRC) as a confinement technique in chloride environment. The investigations demonstrate that TRC has a good reinforcement effect on the concrete columns under chloride-wet-dry cycles. Finally, influence of each parameter is analyzed, which can be used as reference and foundation in actual application.

The extensive development of automated guided vehicles (AGVs) over the last two decades is outlined, and a vehicle for use in small assembly processes such as electronic equipment manufacturing is described. This micro‐AGV is intended for bench‐top use, and is guided by wall sensors between workstations. Traction is provided by two stepper motors, which receive their signals through appropriate drivers from an on‐board microcontroller. This device controls the vehicle in accordance with data stored in a non‐volatile memory, representing the node locations of the workstations in the path. Graphs of speed and electricity consumption against stepper pulse length are presented, and the issue of battery life is discussed. Circuitry for the stepper driver and the microcontroller interface is given. Specific applications of the vehicle in the electronics manufacturing industry are discussed, and a design of processing environment is presented.

To examine the need to develop, practice and implement such maintenance practices, which not only reduce sudden sporadic failures in semi‐automated cells but also reduce both operation and maintenance (O&M) costs.

A case‐based approach in conjunction with standard tools, techniques and practices is used to discuss various issues related with TPM implementation in a semi‐automated cell.

The findings indicate that TPM not only leads to increase in efficiency and effectiveness of manufacturing systems, measured in terms of OEE index, by reducing the wastages but also prepares the plant to meet the challenges put forward by globally competing economies to achieve world class manufacturing (WCM) status.

The paper presents an interesting investigation of TPM implementation issues which may help the managers/practitioners to prepare their plants/units to meet the challenges of competitive manufacturing in twenty‐first century by adopting and implementing TPM.

The success of a company can be measured by many different yardsticks. Criteria taken into consideration may include for instance the ability to innovate and to develop high quality products; the expansion of a small group of products into a wide range that provides a complete package for a specific industry; the capacity to cater for a multiplicity of end applications; or growth in sheer physical size that necessitates a move to extensive purpose‐designed premises. Success can be reflected too in the acquisition of an ever expanding market in geographical terms, and in the gaining of a respected reputation worldwide.

THERE are signs that are only too welcome that the workers of the world, tired of or fearful of continual depression, are at last prepared to take positive steps towards their solution.

The purpose of this paper is to apply group assembly (GA) considerations to the construction industry and to provide evidence of construction sector industrialization with quantitative results. Moreover, a flexible assembly system is proposed, especially designed to cope with variability: this can be easily extendable to other industrial sectors, especially when dealing with extremely variable environments.

The paper presents a case study conducted at an Italian company leader in the design, manufacture and installation of architectural claddings and lightweight continuous facades.

The research empirically demonstrates how the application of GA and the creation of project families lead to consistent enhancement also within the construction industry. The case study reveals great improvement in terms of both operating and ergonomic performances, agile assembly system reconfiguration design and make span reduction. The possibility of correlating a new project to an identified family gives the opportunity to understand the best assembly line layout configuration which should be assigned to the project, to improve the throughput time and the controllability of the assembly process and to guarantee efficient floor space utilization, lead‐time control, accuracy and reliability.

The novelty of the study lies in the way the assembly layout is designed to cope with variability: the assembly line, which is dedicated to more stable processes, is coupled with pre‐assembly stations, easily reconfigurable, meant to be “variability absorbers”. As far as the authors know, this is also the first time GA is applied to the construction industry. Moreover, a timely topic such as construction sector industrialization is confirmed by quantitative results.

This paper aims to speed up finite element analyses of structures with a highly nonlinear material response subjected to many loading cycles.

An approach where large time increments are taken in an adaptive fashion is presented. The size of the large time increments typically spans several loading cycles and is based on Taylor series expansions of the response combined with error control.

The suggested adaptive algorithm is simple compared with some well‐known alternatives in the literature. It also has the inherent convergence property that it reduces to the classical time incrementation in the case where the estimated error is too large.

The algorithm is suitable for (restricted to) a special class of problems where the material response versus a representative time sequence are smooth curves. The simplicity of the method results in a robust algorithm.

Similar algorithms have been presented earlier in the literature but the present work introduces some enhancements, e.g. accounting for general internal variables also in the error estimate. In addition, the present work considers a more complex constitutive model compared with earlier work within the research field.

Karaikal Port Private Limited (KPPL) was a special purpose vehicle created by MARG Group on February 18, 2006 to develop Karaikal port. According to the concession agreement signed for a period of 30 years, KPPL was given rights to Karaikal port on a Build, Operate and Transfer (BOT) basis. It was to phase the building of the port based on short term, midterm and long term demand. By August 22, 2011, Phase I of construction had been completed, and Phase IIA was nearing completion. Though the project had not faced any major problems in its development, there were issues such as restrictions on the availability of land for any future expansion, limited scope of hinterland businesses, small scale environmental issues and others that needed to be addressed for the future development of the port.