706 research outputs found
A Fuzzy inference expert system to support the decision of deploying a military naval unit to a mission
Naval military units are complex systems required to operate in xed time frames in o shore tasks where maintenance operations are drastically limited. A failure during a mission is a critical event that can drastically in
uence the mission success. The decision of switching a unit to a mission hence requires complex judgments involving information about the health status of machineries and the environmental conditions. The present procedure aims to support the decision about
switching a unit to a mission considering the vagueness and uncertainty of information by means of fuzzy theory and emulates the decision process of a human expert by means of a rule-based inference engine. A numerical application is presented to prove the e ectiveness of the approach
The Design of Effective Maintenance Outsourcing Contracts
Recent developments in maintenance planning and
management demonstrate that the establishment of optimized
maintenance policies may drastically improve the
performance and reduce the operating cost of facilities.
However maintenance activities are typically outside of the
core business of production facilities, hence enterprises often
fail to catch the opportunities that may originate by properly
optimized management strategies. A strategic maintenance
management should hence encompass the possibility of
outsourcing maintenance activities to ensure the necessary
perfomance of production systems, while allowing
enterprises to concentrate their resources on their core
activities. In order to be effectively undertaken an
outsourcing strategy must be supported by a proper
performance oriented contract. The present paper aims to
provide an adequate methodology to address such issues and
to define a framework for the definition of the relevant
contract variables such as availability levels, penalty
policies, rewards and service cost. The methodology here
proposed is based upon the evaluation of the expected profit
function of both the outsourcer and the provider, by
performing a trade-off analysis on the basis of the
transaction costs
nanostructured electrodes for biosensing an innovative technology with huge potential applications
n/
A multi objective approach to short food supply chain management
Conventional supply chains, involving several stages and various intermediaries, are affected by some wellknown forms of inefficiencies and drawbacks. Besides the increase of market price consequent to multiple marginalization, such supply chains generally suffer of significant post-harvest losses and product waste. In this context, short food supply chains have been recently proposed as different systems capable of delivering higher quality products while promoting sustainability and efficiency. Across the EU, a growing number of consumers choose to buy food products on local farmers' markets, associating local products with higher quality standards (freshness, nutritional value), healthy eating, more environment-friendly production methods and lower carbon footprint. Such elements seem to confirm a higher performance of short food supply chains (SFSCs) compared to traditional (long) chains in terms of sustainability and quality of products. Nevertheless, the performance of SFSCs is significantly affected by the local contexts and the market situations in which they operate. In particular, although SFSCs are localized in relatively small geographical areas, the elimination of intermediaries, such as distributors/packagers, and quality preserving processes generally results in shorter shelf-life of products. The management of such systems, hence, is focused on the problem of ensuring superior quality of local product at reasonable costs, without the possibility of employing advanced packaging solutions. Therefore, due to their peculiarities, SFSCs require proper logistic policies to cope with these problems, taking into account the variability of demand and the effects of seasonality. This paper in particular focuses on the logistics of SFSCs and proposes a methodology for optimal inventory management, with the aim to preserve the shelf-life of the products, and to ensure supply chain efficiency. The methodology developed is based on a multi-objective approach to inventory management in a serial two-echelon system. A numerical application is proposed in order to prove the effectiveness of the model
Initial Results and Literature Review
Aim: To evaluate the role of stereotactic body radiation therapy in the retreatment of locally recurrent cervical cancers. Brachytherapy is the main choice to treat gynecologic cancers. Methods: Patients with recurrent cervical cancer, previously submitted to radiotherapy, were treated with stereotactic body radiation therapy using a CyberKnife system (Accuray Incorporated, Sunnyvale, California) with a fiducial tracking system. Results: From August 2011 to October 2014, 5 patients have been treated. Median age was 81 years (range, 70-84 years). Two patients were diagnosed with adenocarcinoma endometrioid and 3 with squamous cell carcinoma. Toxicity was scored according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer criteria. After a median follow-up of 12 months (range, 8-34 months), no severe (>grade 3) acute/late genitourinary or low gastrointestinal toxicity was observed. Conclusion: Our preliminary results of stereotactic body radiation therapy "simulating" high dose rate for recurrent cervical cancers confirm a minimal toxicity and an optimal outcome. The stereotactic body radiation therapy is an alternative to high dose rate brachytherapy for gynecologic tumors
A multi-objective approach to solid waste management
The issue addressed in this paper consists in the localization and dimensioning of transfer stations, which constitute a necessary intermediate level in the logistic chain of the solid waste stream, from municipalities to the incinerator. Contextually, the determination of the number and type of vehicles involved is carried out in an integrated optimization approach. The model considers both initial investment and operative costs related to transportation and transfer stations. Two conflicting objectives are evaluated, the minimization of total cost and the minimization of environmental impact, measured by pollution. The design of the integrated waste management system is hence approached in a multi-objective optimization framework. To determine the best means of compromise, goal programming, weighted sum and fuzzy multi-objective techniques have been employed. The proposed analysis highlights how different attitudes of the decision maker towards the logic and structure of the problem result in the employment of different methodologies and the obtaining of different results. The novel aspect of the paper lies in the proposal of an effective decision support system for operative waste management, rather than a further contribution to the transportation problem. The model was applied to the waste management of optimal territorial ambit (OTA) of Palermo (Italy)
Acute inflammatory response in the subcutaneous versus periprosthethic space after incisional hernia repair: an original article
BACKGROUND: The acute inflammatory response following mesh implantation has been often evaluated in vitro and in animal models. The aim of this study was to evaluate the acute inflammatory response near the prosthesis in human by analysing some inflammatory indicators.METHODS: We used a cohort of twelve male patients affected by midline incisional hernia, who were admitted for surgical mesh repair. A suction drain was placed between the mesh and rectal muscles whereas, the other one was placed between the subcutaneous tissue and the oblique external sheath. The acute inflammatory response was analyzed by measuring the production of interleukin [IL]-1, IL-10, IL-1ra, C-Reactive Protein (CRP), total proteins, albumin and pH in the drain fluids.RESULTS: The dynamics of CRP and ILs production resulted similar in both drainages. Comparing drain over mesh and subcutaneous drain at all times, IL-1 and CRP values always resulted significantly higher in the first one, whereas IL-1ra and IL-10 values were significantly higher in the last one. Total protein and albumin were similar in both drains at all time; only in the drain over mesh fluid, pH values resulted significantly reduced in the fourth post-operative day.CONCLUSIONS: Our data showed that an acute inflammatory reaction is present in both sites examined. However, it was significantly higher in the space after mesh implantation
Machine Learning approach towards real time assessment of hand-arm vibration risk
In industry 4,0, the establishment of an interconnected environment where human operators cooperate with the machines offers the opportunity for substantially improving the ergonomics and safety conditions of the workplace. This topic is discussed in the paper referring to the vibration risk, which is a well-known cause of work-related pathologies. A wearable device has been developed to collect vibration data and to segment the signals obtained in time windows. A machine learning classifier is then proposed to recognize the worker’s activity and to evaluate the exposure to vibration risks. The experimental results demonstrate the feasibility and effectiveness of the methodology proposed
A Multi-Criteria Decision-Making Framework for Zero Emission Vehicle Fleet Renewal Considering Lifecycle and Scenario Uncertainty
In the last decade, with the increased concerns about the global environment, attempts have been made to promote the replacement of fossil fuels with sustainable sources. For transport, which accounts for around a quarter of total greenhouse gas emissions, meeting climate neutrality goals will require replacing existing fleets with electric or hydrogen-propelled vehicles. However, the lack of adequate decision support approach makes the introduction of new propulsion technologies in the transportation sector a complex strategic decision problem where distorted non-optimal decisions may easily result in long-term negative effects on the performance of logistic operators. This research addresses the problem of transport fleet renewal by proposing a multi-criteria decision-making approach and takes into account the multiple propulsion technologies currently available and the objectives of the EU Green Deal, as well as the inherent scenario uncertainty. The proposed approach, based on the TOPSIS model, involves a novel decision framework referred to as a generalized life cycle evaluation of the environmental and cost objectives, which is necessary when comparing green and traditional propulsion systems in a long-term perspective to avoid distorted decisions. Since the objective of the study is to provide a practical methodology to support strategic decisions, the framework proposed has been validated against a practical case referred to the strategic fleet renewal decision process. The results obtained demonstrate how the decision maker's perception of the technological evolution of the propulsion technologies influences the decision process, thus leading to different optimal choices
- …