1,720,964 research outputs found
Improving management effectiveness and overall performance of software development projects through a system dynamics approach
Full text linkWhile existing research has mainly focused on project management’s static view, our work investigates the impacts
of projects’ structure and behavioural dynamics on their performance, with a specific focus on the influence of some
peculiar development processes. A dynamic simulation model of a single phase project was built using the system
dynamics methodology. The model integrates several previously developed and tested project structures and adds a
separate structure for the negotiation process. Simulations describe the behaviours generated by the interaction of
customized development processes in single-phase projects. Project performances are measured in terms of time,
quality and cost. Our research aims to show that development processes, as well as shared resource levelling
techniques, significantly impact the dynamic behaviour of projects through the feedback, delays and nonlinear
relationships which are usually omitted in traditional project management practice, as well as in methods, tools and
models, but are very important descriptors of project complexity. Expanding the models used to manage projects to
include dynamic features requires a change of focus by researchers and practitioners. The system dynamics
methodology provides some of the tools for developing and implementing such an expansion in project models
Sustainable trasportation systems: dynamic routing optimization for a last-mile distribution fleet
No full textLogistics costs control has always been considered a key issue for business development. In order to decrease transportation costs, companies are pushed to negotiate lower logistic service prices with Third-Party Logistics Service Providers (3PL) which, in turn, should be able to optimize their processes and reduce their costs in order to preserve the adequate profitability and allow their industrial customers to gain competitive advantage. In this paper a method to reduce industrial costs and negative externalities associated with fleet management on an Hub & Spoke transportation network is presented. We state that the Time Dependent VRP with Pick-up and Deliveries and Time Windows model may be the most suitable for goods distribution problem inside large cities. A dynamic version capable to consider road traffic along with variable congestion effects during the day has been created. Hence, we proposed a quick and flexible heuristic that has been validated with the real data of a subsidiary of a 3PL leader in the express transportation sector. The heuristic has demonstrated to be able to reduce travel time, travelled distance and, at the same time, significantly increase the service level, on top of the relative benefit for the community coming from a substantial reduction of air pollution, noise pollution, congestion and incidentally
Depannage and other maintenance strategies for transportation fleets
Full text linkThis paper addresses the problem of designing a depannage service network for freight transportation fleets in order to fill up an evident gap in Operations Management literature. As a matter of
fact, breakdowns have a significant impact on service level and an efficient and effective assistance service is needed in order to guarantee competitive advantage. Aiming at laying the foundations for further research on modelling and solving the considered problem, a literature review is performed for identifying analogies with other problems, already approached in the past, and stating the problem. Finally, parameters, decision variables and objective function that should be considered for modelling and solving the problem are proposed, trying to stimulate the discussion on a new research theme and, more specifically, on the integration of decisions at strategic, tactical and operational level into a systemic model
An Operations management approach for radiology services
Full text linkThis paper focus on the application of Operations Management techniques in the context of radiological and diagnostic imaging services provision. More specifically, the outpatient appointment
scheduling problem for MRI diagnostic imaging services in a radiology clinics is approached and solved taking into account set-up time minimization. This is pursued trough the design of an innovative system for the on-line assignment of appointments for specific diagnostic imaging scans. An appointment rule, a patient
classification and an heuristic procedure for the booking process are defined in order to better manage uncertainty and improve system performance. The proposed approach was validated on the case of a diagnostic centre of Alliance Medical, a primary multinational company in the field of diagnostic imaging services
Supply chain network design for the diffusion of a new product
Full text linkSupply Chain Network Design (SCND) deals with the determination of the physical configuration and infrastructures of the supply chain. Specifically, facility location is one of the most critical decisions: transportation, inventory and information sharing decisions can be readily re-optimized in response to changes in the context, while facility location is often fixed and
difficult to change even in the medium term. On top of this, when designing a supply network to support a new product diffusion (NPD), the problem becomes both dynamic and stochastic. While literature concentrated on approaching SCND for NPD separately coping with dynamic and stochastic issues, we propose an integrated optimisation model, which allows warehouse positioning decisions in concert with the demand dynamics during the diffusion stage of an innovative product/service. A
stochastic dynamic model, which integrates a Stochastic Bass Model (SBM) in order to better describe and capture demand dynamics, is presented. A myopic policy is elaborated in order to solve and validate on the data of a real case of SCND with 1,400 potential market points and 28 alternatives for logistics platforms
A logistics provider evaluation and selection methodology based on AHP and linear programming integration.
No full textIn the AHP procedure, experts are asked to provide a numerical quantification in pair-wise comparisons; when dealing with several criteria, inconsistency may rise and Saaty’s Consistency Ratio threshold helps in identifying those matrices to be rejected or those interviews to be repeated. However, in certain domains, a faster way to proceed in the determination of the criteria weight is appreciated, along with the opportunity of merging the experts’ indications with objective judgments originating from historical data analysis. This is the case of several industrial firms which have to perform a supplier selection. In this paper, we propose an evaluation method that combines AHP, DEA and Linear Programming in order to support multi-criterion decisions of Third Party Logistics providers: a rewarding/penalizing effect, depending on the suppliers past performance, is used to correct the errors resulting from biased quantification of weights in AHP. The proposed model has been validated on the real case of an international Logistics Service Provider
A stochastic dynamic programming approach for integrating supply chain network design and new product diffusion
Full text linkWe focus on the problem of designing a supply chain for a new product. We propose a stochastic dynamic program based on a Stochastic Bass Model of the product demand dynamics. We heuristically solve our model using Monte Carlo simulation and math programming techniques. We apply our approach to the case of a new distribution service for Made-in-Italy wine and food products, benchmarking the performance of our heuristic policy against the performance of an easier to compute heuristic policy and a lower bound
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Simplifying the Virtual Safety Stock formula
Full text linkThe paper deepen the analysis into the Virtual Safety Stock theory, which is an approach intended to drastically reduce safety inventory levels exploiting the eventual time lag between the moment when a product is ordered and the time the product needs to be available, while preserving the same performance as a production system that operates with physical safety stock. The original virtual safety stock definition embeds two major problems: a double Gaussian integral in the formulation together with the heritage of the unrealistic assumptions already included in the earliest Hadley and Whitin’s safety stock conception. This paper describes an alternative approach in which the virtual safety stock is defined with a closed-form expression much easier to compute and use in operations management practice
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