Use of Amplatzer vascular plug to treat a biliary cutaneous fistula

Several substances have been used in an attempt to sclerose biliary ducts associated with persistent biliary-cutaneous fistula (BCF). The AMPLATZER Vascular Plug (AVP; AGA Medical, USA) system is a recently developed endovascular occlusion device, introduced as an alternative to permanent embolic materials (metallic coils or acrylic glue), in the occlusion of large and medium-calibre arteries and veins. We report a successful use of the AVP to embolize BCF, developed after the removal of an internal-external biliary drainage

Fault Detection by Labeled Petri Nets in Centralized and Distributed Approaches

This paper addresses the problem of online fault de- tection and diagnosis in discrete event systems modeled by labeled Petri nets and using Integer Linear Programming Problem (ILPP) solutions. In particular, unobservable (silent) transitions model faults and both observable and unobservable transitions model the nominal system behavior. Furthermore, observable transi- tions exhibit a kind of non determinism since several different transitions may share the same event label. This paper proposes two diagnosers that work in two different system settings. The first one is a centralized fault detection strategy: the diagnoser waits for an observable event and an algorithm defines and solves some ILPPs to decide whether the system behavior is normal or may exhibit some faults. In the second setting, the system consists of a set of interacting PN modules and each module is monitored by a diagnoser that has local information on the module structure. Moreover, each diagnoser observes and detects the faults of the module it is attached to and shares information in some of its places that are shared with other modules of the system. Some case studies show the two different approaches and point out the peculiarities of the proposed strategies

New Consensus Algorithms Based on a Positive Splitting Approach

The paper proposes new consensus protocols for the agreement problem in networks of agents with a discrete time model. A new class of consensus algorithms is introduced on the basis of the positive splitting of the standard iteration matrix. In the framework of non negative matrix theory, some results are proved to guarantee the convergence of the proposed algorithms. In addition, numerous numerical experiments show that the proposed iterative schemes enjoy good rate of convergence even in the cases in which the standard iterative algorithms do not guarantee good performance

Assignment of electrical vehicles to charging stations by a distributed approach

This paper presents a solution for the distributed dynamic assignment of a set of electric vehicles to a network of charging stations. The drivers of the vehicles send requests for the charging of their own vehicle; then they receive the location of the station to reach for the battery charging. The problem is solved using some distributed multi-agent assignment algorithms: the stations reach a consensus solving some local integer linear programming problems. Moreover, the convergence of the algorithms is proved and an example shows the efficiency of the proposed solution. \ua9 2014 EUCA

On-line Fault Detection of Discrete Event Systems by Petri Nets and Integer Linear Programming

The paper addresses the fault detection problem for discrete event systems in a Petri Net (PN) framework. Assuming that the structure of the PN model and the initial marking are known, faults are modelled by unobservable transitions. Moreover, we assume that there may be additional unobservable transitions associated with the system legal behaviour and that the marking reached after the firing of any transition is unknown. The proposed diagnoser works on-line: it waits for the firing of an observable transition and employs an algorithm based on the definition and solution of some integer linear programming problems to decide whether the system behaviour is normal or exhibits some possible faults. The results characterize the properties that the PN modelling the system fault behaviour has to fulfill in order to reduce the on-line computational effort

A three level strategy for the design and performance evaluation of Hospital Departments: A case study

The efficient management of hospital departments (HDs) has recently become an important issue. Indeed, the increased demand and design for hospital services have saturated the capacity of HD that requires suitable tools for the efficient use of resources and flow of patients, staff, and drugs. This paper proposes a model based on a three-level strategy to design at the tactical level in a concise and effective way the structure, the resources, and the dynamics of a critically congested HD. The design strategy is composed of three basic elements: the modeling module, the optimization module, and the simulation and decision module. The first module employs a Unified Modeling Language tool and a timed Petri net (PN) model to effectively capture the detailed flow and dynamics of patients, starting from their arrival to the HD until their discharge. The optimization module employs the fluid relaxation to concisely approximate in a continuous PN framework the HD model and optimize suitable performance indices. The simulation module verifies that the optimized parameters allow an effective workflow organization while maximizing the patient flow. In case of inconsistencies due to the fluid approximation between the continuous model used in the design phase by the optimization module and the discrete one used in the subsequent verification phase by the simulation module, the latter module revises the values of some HD model parameters. A real case study on the Emergency Cardiology Department of the General Hospital of Bari (Italy) shows the efficiency and accuracy of the proposed method