Διαδικασίες ανάθεσης δημοσίων συμβάσεων με διαπραγματεύσεις

Αντικείμενο της μελέτης είναι οι διαδικασίες ανάθεσης δημοσίων συμβάσεων, οι οποίες επιτρέπουν στο προσυμβατικό στάδιο τη διεξαγωγή διαπραγματεύσεων μεταξύ δημοσίων αρχών και οικονομικών φορέων, προκειμένου οι πρώτες να διαμορφώσουν τη βούλησή τους αφενός, ως προς τον καθορισμό του αντικειμένου και των όρων της υπό κατάρτιση σύμβασης, αφετέρου, ως προς την επιλογή αντισυμβαλλομένου. Η ανταγωνιστική διαδικασία με διαπραγμάτευση, ο ανταγωνιστικός διάλογος, η σύμπραξη καινοτομίας, αλλά και η εξαιρετική διαδικασία με διαπραγμάτευση χωρίς δημοσίευση προκήρυξης, αποτελούν τέτοιου είδους διαδικασίες. Στο δίκαιο των δημοσίων συμβάσεων η διαπραγμάτευση νοείτο διαχρονικά ως έννοια αντίθετη στον ανταγωνισμό και τη διαφάνεια, τις δύο θεμελιώδεις συνιστώσες του ενωσιακού πλαισίου για τις δημόσιες συμβάσεις, για το λόγο δε αυτό η απαγόρευση διαπραγμάτευσης είχε αναχθεί σε βασικό σύνθημα και κανόνα κατά την κατάρτιση τους, ενώ αντίθετα η δυνατότητα διαπραγμάτευσης σε αναγκαία εξαίρεση. Ενόψει τούτου, η στροφή του ενωσιακού νομοθέτη σε ευέλικτες διαδικασίες που συνδυάζουν διαπραγματεύσεις και δημοσιότητα, η οποία διαφαίνεται μέσα από από τις νέες οδηγίες για τις δημόσιες συμβάσεις, 2014/24/ΕΕ και 2014/25/ΕΕ, παρίσταται ίσως ως η σημαντικότερη μεταβολή που επήλθε στο θεσμικό πλαίσιο των δημοσίων συμβάσεων

Turbocharger Lubrication - Lubricant Behavior and Factors That Cause Turbocharger Failure

This paper is a review of the turbocharger lubrication system and at the same time an attempt to point out and analyze the factors responsible for turbocharger wear, damage and failures. In particular, the conditions under which the lubricant works are presented, from its entrance up to its exit from the turbocharger bearing housing. Additionally, the consequences of failure to comply with the instructions for appropriate turbocharger operation are provided by the various manufacturers. Water cooled turbochargers (for which engine coolant is used), contribute significantly to the reduction of lubricant temperature, in the critical zones of its operation. This is achieved by reducing, the danger of the oil “coking” effect (charred oil residues) or its decomposition, because of high temperature occurring in these zones. Turbochargers shaft support development using semi-floating bush bearings has a significant impact on turbocharger manufacturing cost, as well as on their operational features. Further benefit may be had, when ball bearings are used (usually angular contact bearings are used) for turbocharger shaft support as they provide: a) a reduction of the kinetic friction coefficient, b) reduction of turbocharger lag during turbocharger shaft acceleration from low to high speeds, and c) reduced sealing problems. Regarding the failures that occur in turbochargers, their majority - up to 50% - is caused by problematic lubrication [1]. The rest of the failures are divided between causes related to human factors (such as misuse and inadequate maintenance of a turbocharged vehicle) and external factors such as foreign objects entering either the compressor or turbine housings

Wire-speed hardware-assisted traffic filtering with mainstream network adapters

Abstract. Modern computer architectures are founded on multi-core processors. In order to efficiently process network traffic, it is necessary to dynamically split high-speed packet streams across cores based on the monitoring goal. Most network adapters are multi-core aware but offer limited facilities for assigning packets to processor cores. In this paper we introduce a hybrid traffic analysis framework that leverages flexible packet balancing mechanisms available on recent 10 Gbit commodity network adapters not yet exploited by operating systems. The main contribution of this paper is an open source hardware-assisted software layer for dynamically configuring packet balancing policies in order to fully exploit multi-core systems and enable 10 Gbit wire-speed network traffic analysis

vPFRING: Towards WireSpeed Network Monitoring using Virtual Machines

The demand of highly flexible and easy to deploy network monitoring systems has pushed companies toward software based network monitoring probes implemented with commodity hardware rather than with expensive and highly specialized network devices. Deploying software probes under virtual machines executed on the same physical box is attractive for reducing deployment costs and for simplifying the management of advanced network monitoring architectures built on top of heterogeneous monitoring tools (i.e. Intrusion Detection Systems and Performance Monitoring Systems). Unfortunately, software probes are usually not able to meet the performance requirements when deployed in virtualized environments as virtualization introduces severe performance bottlenecks when performing packet capture, which is the core activity of passive network monitoring systems. This paper covers the design and implementation of vPF_RING, a novel framework for efficiently capturing packets on virtual machines running on commodity hardware. This solution allows network administrators to exploit the benefits of virtualization such as reduced costs and centralized administration, while preserving the ability to capture packets at wire speed even when deploying applications in virtual machines. The validation process has demonstrated that this solution can be profitably used for multi-gigabit network monitoring, paving the way to low-cost virtualized monitoring systems

Τεχνοοικονομική ανάλυση της λειτουργίας των κεντρικών αντλιοστασίων πόσιμου νερού και λυμάτων του Δήμου Ρεθύμνου

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