In this paper we propose a 4-index formulation for the uncapacitated multiple allocation hub location problem tailored for urban transport and liner shipping network design. This formulation is very tight and most of the tractable instances for MIP solvers are optimally solvable at the root node. While the existing state-of-the-art MIP solvers fail to solve even small size instances of problem, our accelerated and efficient primal (Benders) decomposition solves larger ones. In addition, a very efficient greedy heuristic, proven to be capable of obtaining high quality solutions, is proposed. We also introduce fixed cost values for Australian Post (AP) dataset. 相似文献
Manufacturing decisions inherently face uncertainties and imprecision. Fuzzy logic, and tools based on fuzzy logic, allow for the inclusion of uncertainties and imperfect information in decision making models, making them well suited for manufacturing decisions. In this study, we first review the progression in the use of fuzzy tools in tackling different manufacturing issues during the past two decades. We then apply fuzzy linear programming to a less emphasized, but important issue in manufacturing, namely that of product mix prioritization. The proposed algorithm, based on linear programming with fuzzy constraints and integer variables, provides several advantages to existing algorithm as it carries increased ease in understanding, in use, and provides flexibility in its application. 相似文献
Suppliers have become an increasingly important source of product and process innovation. While case studies have documented how supplier innovation can benefit a manufacturer, this relationship has not been empirically validated, nor have contingencies been explored. Using organizational learning theory we posit that the link between supplier innovativeness and manufacturer performance is moderated by the “fit” between the learning styles of the manufacturer and supplier. We empirically test our hypotheses using hierarchical linear modeling of survey responses from 148 manufacturers concerning 592 suppliers. Results indicate that supplier innovativeness has positive impacts on multiple dimensions of manufacturer performance. Results show that when the outsourced activity involves low levels of design responsibility by the supplier, it is more beneficial for the two partners to have contrasting learning styles. However, when the outsourced activity is design-intensive, it is more beneficial to have a supplier with an explorative learning style. 相似文献
Quality & Quantity - Cinema has a complex relation with the state and social reality in Iran. Between 2001 and 2004, Iranian cinema was under the control of the ideology of the Islamic Left.... 相似文献
This paper is concerned with model development for a short-term fleet deployment problem of liner shipping operations. We first present a mixed integer nonlinear programming model in which the optimal vessel speeds for different vessel types on different routes are interpreted as their realistic optimal travel times. We then linearize the proposed nonlinear model and obtain a mixed integer linear programming (MILP) model that can be efficiently solved by a standard mixed integer programming solver such as CPLEX. The MILP model determines the optimal route service frequency pattern and take into account the time window constraints of shipping services. Finally, we report our numerical results and performance of CPLEX on randomly generated instances. 相似文献
Despite dedicated effort and research in the last two decades, the entrepreneurship field is still limited by little evidence-based knowledge of the impacts of entrepreneurship programs on the entrepreneurial intention of students in pre-university levels of study. Further, gender equity continues to be an issue in the entrepreneurial sector, particularly in STEM-focused entrepreneurship. In this context, this study was designed to explore the effects of a one-day female-focused STEM-based entrepreneurship program (for brevity, we call it the OzGirlsEntrepreneurship program) on the entrepreneurial intention of secondary school female students. The study collected data from two surveys completed by 193 secondary school female students, aged 14–16 years, who participated in the OzGirlsEntrepreneurship program. This program encouraged girls to develop and implement creative computational solutions to socially relevant problems, with an Internet of Things (IoT) component using the micro:bit device. The findings reveal that a key factor in the development of entrepreneurial attitudes in young female students is associated with soft-skills development, particularly in the areas of creative thinking, risk-taking, problem-solving, and leadership development. The importance of meaningful human connections, including positive role modelling and peer to peer learning were also important factors in fostering entrepreneurial intent. With these factors in mind, our findings highlight that the OzGirlsEntrepreneurship program substantially increased the entrepreneurial intention of secondary school female students. In addition, this study offers actionable implications and recommendations to develop and deliver entrepreneurship education programs for secondary school level students.
Increasingly manufacturers implement lean practices to improve operational performance. In addition, manufacturers operate in ever more complex and volatile environments. This research investigates the effects of environmental complexity and dynamism on lean operations and lean purchasing practices. It empirically examines these relationships using archival and survey data from 126 manufacturers. The results show that environmental complexity positively moderates the effects of lean operations and lean purchasing on performance. However, environmental dynamism reduces the benefits of lean operations on performance, but enhances the benefits of lean purchasing on performance. Robustness tests further confirm the contingent effects of complexity and dynamism on lean operations and lean purchasing. This research offers a more nuanced understanding of the effect of external environmental context on lean practices, and suggests that practitioners should carefully consider the external environment when implementing different types of lean practices. 相似文献
A mixed integer programming formulation is proposed for hub-and-spoke network design in a competitive environment. It addresses the competition between a newcomer liner service provider and an existing dominating operator, both operating on hub-and-spoke networks. The newcomer company maximizes its market share—which depends on the service time and transportation cost—by locating a predefined number of hubs at candidate ports and designing its network. While general-purpose solvers do not solve instances of even small size, an accelerated Lagrangian method combined with a primal heuristic obtains promising bounds. Our computational experiments on real instances of practical size indicate superiority of our approach. 相似文献