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Nowadays, the defense industry is considered a significant part of the manufacturing industries. Military products in the world have a high level of diversity, delivery speed and appropriative operational functionality. Therefore, various producing, high quality and high-speed delivery of military products are of great importance in enhancing Iran’s defensive power. Defense industries’ supply chain agility is a response to how to produce military products with these features. Therefore, the purpose of this paper is to provide a model for the agile supply chain of defense industries to show the relationship between agile practices and their hierarchy.

First, the authors identify the most important supply chain agility practices by expert’s questionnaire. Then, using factor analysis, practices are categorized and validated based on structural equation modeling (SEM). SEM showed a meaningful relationship between agile supply chain practices. Finally, using interpretative structural modeling, a model is presented to show the logical relationships and hierarchy between these practices.

The results show that out of a total of 62 practices introduced in the previous research for the agile supply chain, 37 practices in the agility of the supply chain of defense industries are effective. The 4 new agility practices were identified in this research. These 41 practices were classified into 8 categories including supplier relationship, workshop level management, organizational structure improvement, human resource management, product designing, improve and integrate the process, application of information technology and customer relationship. Improvement of organizational structure was at the highest level of the model. Therefore, managers first should focus on it.

Given the confidentiality of information in the defense industry, the distribution of questionnaires and their collection was one of the most important limitations. A variety of defense products in land, air and sea areas, and a large number of industries in each sector, forced the authors to select the only land area. Although the results of this research can be used in the air and sea areas, but cannot be said that the implementation of this study presented model will fully lead to the defense industries’ supply chain agility in air and sea sectors.

This is the first research on the supply chain agility of Iran’s defense industry that bridges the gap between theory and practice. The classification of 41 practices in the form of 8 measures and examining the relationship between them is a new and practical approach for understanding the relationships between different variables that affect supply chain agility. This study introduces four new agility practices including the use of new technology and equipment, human resource balance, the use of expert human resources, training and employee empowerment, which can be considered in many industries of developing or less developed countries. Considering the specific situation of defense industry supply chain in comparison with other industries, the results of this research can be used by other defense industries of similar countries.

As a critical problem in sophisticated distribution systems, vehicle routing plays a pivotal role in dealing with time windows and capacities constraints. The purpose of this paper is to addresses a new integrated model to incorporate both three-dimensional and time windows aspects of the routing problem. First, capacitated vehicle routing decisions are made subject to a soft time interval to meet the customers’ demands. Afterward, these decisions are entered into the three-dimensional loading problem.

The problem is solved using generalized algebraic modeling system software in small-size problems. The problem is NP-hard and requires an efficient solution methodology. For this purpose, a hybrid algorithm has been proposed to solve the large-size problems. The efficiency of this algorithm is checked by making comparisons with exact solutions for small and medium size test problems, and with the related literature for large size problems.

The numerical experiments show that the proposed model covers more effectively the broader aspects of the transportation problem. Furthermore, the proposed algorithm supports competitive and satisfactory results by giving reasonable outputs in comparison with previous studies.

The main purpose of this integration is to achieve minimum total transportation costs, which cannot be guaranteed without applying two referred constraints, simultaneously.

Line–cell conversion and rotation of operators between cells are common in lean production systems. Thus, the purpose of this study is to provide an integrated look at these two practices through integrating job rotation scheduling and line-cell conversion problems, as well as investigating the effect of rotation frequency on flow time of a Seru system.

First, a nonlinear integer programming model of job rotation scheduling problem and line–cell conversion problem (Seru-JRSP) was presented. Then, because Seru-JRSP is NP-hard, an efficient and effective invasive weed optimization (IWO) algorithm was developed. Exploration process of IWO was enhanced by enforcing two shake mechanisms.

Computations of various sample problems showed shorter flow time and less number of assigned operators in a Seru system scheduled through job rotation. Also, nonlinear behavior of flow time versus number of rotation periods was shown. It was demonstrated that, setting number of rotation frequency to one in line with the literature leads to inferior flow time. In addition, ability of developed algorithm to generate clusters of equivalent solutions in terms of flow time was shown.

In this research, integration of job rotation scheduling and line–cell conversion problems was introduced, considering lack of an integrated look at these two practices in the literature. In addition, a new improved IWO equipped with shake enforcement was introduced.

Virtual maintenance simulation is of great importance to help designers find and avoid design problems. During its simulation phase, besides the high precision requirement, collision detection must be suitable for all irregular objects in a virtual maintenance environment. Therefore, in this paper, a collision detection approach is proposed based on encapsulation for irregular objects in the virtual maintenance environment.

First, virtual maintenance simulation characteristics and several commonly used bounding boxes methods are analyzed, which motivates the application of encapsulation theory. Based on these, three different encapsulation methods are oriented to the needs of simulation, including encapsulation of rigid maintenance objects, flexible maintenance objects and maintenance personnel. In addition, to detecting collisions accurately, this paper divides the detection process into two stages. That is, in the first stage, a rough detection is carried out and then a tiny slice space is constructed to generate corresponding capsule groups, which will be redetected in the secondary stage. At last, several case studies are applied to illustrate the performance of the methodology.

The automatic construction algorithm for bounding boxes can be adapted to all forms of objects. The number of detection primitives are greatly reduced. It introduces the reachable space of the human body in maintainability as the collision search area.

The advantages of virtual maintenance simulation could also be advantageous in the industry with further studies. The paper believes this study is of particular interest to the readers of your journal.