A Simple Python Testbed for Federated Learning Algorithms

Nowadays many researchers are developing various distributed and decentralized frameworks for federated learning algorithms. However, development of such a framework targeting smart Internet of Things in edge systems is still an open challenge. In this paper, we present our solution to that challenge called Python Testbed for Federated Learning Algorithms. The solution is written in pure Python, and it supports both centralized and decentralized algorithms. The usage of the presented solution is both validated and illustrated by three simple algorithm examples.Comment: 6 pages, 7 figures, 3 algorithms, as accepted at ZINC 2023, Published by IEEE Xplor

Redundancy in Communication Networks for Smart Grids

Traditional electric power grids are currently undergoing fundamental changes: Representative examples are the increase in the penetration of volatile and decentralized renewable-energy sources and the emerging distributed energy-storage systems. These changes are not viable without the introduction of automation in grid monitoring and control, which implies the application of information and communication technologies (ICT) in power systems. Consequently, there is a transition toward smart grids. IEEE defines smart grid as follows: "The integration of power, communications, and information technologies for an improved electric power infrastructure serving loads while providing for an ongoing evolution of end-use applications" . The indispensable components of the future smart grids are the communication networks. Many well-established techniques and best practices, applied in other domains, are revisited and applied in new ways. Nevertheless, some gaps still need to be bridged due to the specific requirements of the smart-grid communication networks. Concretely, a challenging objective is to fulfill reliability and low-delay requirements over the wide-area networks, commonly used in smart grids. The main ``playground" for the work presented in this thesis is the smart-grid pilot of the EPFL campus. It is deployed on the operational $20kV$ medium-voltage distribution network of the campus. At the time of the writing of this thesis, the real-time monitoring of this active distribution network has been already put in place, as the first step toward the introduction of control and protection. The monitoring infrastructure relies on a communication network that is a representative example of the smart-grid communication networks. Keeping all this in mind, in this thesis, the main topic that we focus on, is the assurance of data communication over redundant network-infrastructure in industrial environments. This thesis consists of two parts that correspond to the two aspects of the topic that we address. In the first part of the thesis, we evaluate existing, well-established, technologies and solutions in the context of the EPFL smart-grid pilot. We report on the architecture of the communication network that we built on our campus. In addition, we go into more detail by reporting on some of the characteristics of the devices used in the network. We also discuss security aspects of the MPLS Transport Profile (MPLS-TP) which is one of the proposed technologies in the context of smart grids. In the second part of this thesis, we propose new solutions. While designing our campus smart-grid network, we analyzed the imposed requirements and recognized the need for a solution for reliable packet delivery within stringent delay constraints over a redundant network-infrastructure. The existing solutions for exploiting network redundancy, such as the parallel redundancy protocol (PRP), are not viable for IP-layer wide-area networks, a key element of emerging smart grids. Other solutions (MPLS-TP for example) do not meet the stringent delay requirement. To address this issue, we present a transport-layer solution: the IP-layer parallel redundancy protocol (iPRP). In the rest of the thesis, we analyze the methods for implementing fail-independent paths that are fundamental for the optimal operation of iPRP, in SDN-based networks. We also evaluate the benefits of iPRP in wireless environments. We show that, with a help of iPRP, the performance of the communication based on the Wi-Fi technology can be significantly improved

Kontrola snage bazne stanice u GSM: utjecaj gustoće korisnika u stanici

In this paper is presented that base station output power can be decreased by the power control in each channel. In this case very important is the distribution function of users\u27 density in the cell. We present the examples of the cells without power control and the examples of the cells with power control, where the distribution of users\u27 density in the cell is of various types. Some results are compared to the results of measurements, and some to the results obtained by simulation.U radu se pokazuje da se izlazna snaga bazne stanice može smanjiti upravljanjem snage pojedinih kanala. U tom slučaju značajnu ulogu ima funkcija raspodjele gustoće korisnika u stanici. Dati su primjeri stanica bez upravljanja snagom i primjeri stanica s upravljanjem snagom gdje je raspodjela gustoće korisnika u stanici različitog tipa. Neki rezultati upoređeni su s rezultatima mjerenja, a neki sa simulacijskim rezultatima

Effects of n-3 Fatty Acids Supplementation on Plasma Phospholipids Fatty Acid Composition in Patients with Obstructive Jaundice- a Pilot Study

Nutritional and immunological status of patients with obstructive jaundice is usually severely altered, with high mortality rates. The n-3 polyunsaturate fatty acids (PUFA), particularly eicosapentaenoic acid (EPA, 20:5 n-3), posess potent immunomodulatory activities. Thus, our aim was to compare the plasma phospholipid fatty acid (FA) composition of these patients with healthy subjects, as well as before and after 7 days preoperative supplementation with high doses of EPA (0.9 g per day) and docosahexaenoic acid (DHA, 22:6 n-3, 0.6 g per day). We found impaired FA status in obstructive jaundice patients, especially EPA, DHA and PUFA, but significantly increased content of total n-3 FA, 22:5 n-3 FA and particularly EPA, which increased more than 3 fold, after 7 days supplementation. In addition, the n6/n3 ratio significantly decreased from 14.24 to 10.24, demonstrating severely improved plasma phospholipid profile in these patients after the intervention

Performance Comparison of Node-Redundant Multicast-Distribution Trees in SDN-Based Networks

Some of the industrial processes with hard real-time constraints, such as those commonly found in the context of smart grids, require very reliable packet delivery and multicast. Solutions such as PRP assume deployments over redundant and dedicated networks. SDN gives us an unprecedented opportunity to obtain the same result by using a shared telecom infrastructure instead of privately owned networks. Nevertheless, there is a challenging question of how to provide node-redundant multicast-distribution-trees. We review existing graph-theoretical algorithms that were proposed for similar problems and propose three algorithms that are suitable for our smart-grid setting. Then, we evaluate their performance in the context of SDN networks. We use as metrics the number of forwarding rules that need to be installed on SDN switches, the number of hops between source-destination pairs given the installed forwarding rules, and the number of sources that can be placed in the network given the capacity constraints

Organic composition of Igalo bay peloid (Montenegro)

837-848Igalo peloid is known for a number of therapeutic properties (resort of healing, cosmetic or aesthetic application) and its closeness of the sea, which makes the peloid extremely valuable. So far, the organic composition of the Igalo peloid was not investigated or determined. Also, there are studies for its medical application and biological activity, which are directly related to its chemical composition. In this paper we analyzed the content of organic compounds (fatty acids, proteins, amino acids, sugars) and we also listed their main and well-known biological, pharmaceutical and medical roles and purposes. For the purpose of this study, different analytical techniques were applied to the collected peloid, including extraction, chromatographic, electrophoretic and NMR techniques

Experimental Validation of the Usability of Wi-Fi over Redundant Paths for Streaming Phasor Data

Applications performing streaming of phasor- measurement data require low latency and losses from the communication network. Traditionally, such requirements are realized through wired infrastructure. Recently, wireless infras- tructure has gained attention due to its low-cost and ease of deployment, but its poor quality-of-service is a strong deterrent for use in mission-critical applications. Recent studies have used measurements to explore the use of packet replication over redundant Wi-Fi paths, for obtaining the desired loss performance without hampering the end-to-end latency. However, these studies are done in a controlled, laboratory environment and do not reflect the real, in-field performance. In this paper, we perform extensive measurements using two co-located directional Wi-Fi links in a real-life setting, to experimentally validate the use of packet replication over Wi-Fi for streaming phasor data. In the setting that we evaluated, we find that the two channels are not fail-independent but the performance achieved with replication is very close to what it would be if they were to be independent. From the loss and latency statistics after replication, we conclude that replicating the phasor data over redundant Wi-Fi paths is a viable option for achieving the desired quality-of-service

iPRP: Parallel Redundancy Protocol for IP Networks

Reliable packet delivery within stringent time limits is a key requirement of smart-grid and other industrial communication networks. The Parallel Redundancy Protocol (PRP), used in this context, duplicates packets at the MAC layer over parallel networks and is thus claimed to repair packet loss in 0 ms. However, PRP has several drawbacks: it works only for bridged networks; it requires special hardware; as a layer 2 protocol, it does not have diagnostic tools; it imposes the same MAC addresses to different interfaces, which exacerbates the management difficulty; multicast packet delivery is not natively supported. To address these problems we propose the IP Parallel Redundancy Protocol (IPRP). Unlike PRP, IPRP works in routed networks. It supports UDP applications, unicast or multicast. It is transparent to applications and requires no changes in application software. It is also transparent to the network as IPRP-related packets are regular IP packets; it requires no specific hardware. Operation at the IP layer, possibly with more than two networks makes the design of IPRP very different from PRP. We implemented IPRP in Linux 3.6.11-rt29 using iptables and deployed it on a campus smart grid. We describe our implementation and some performance results

iPRP - the Parallel Redundancy Protocol for IP Networks: Protocol Design and Operation

Reliable packet delivery within stringent delay-constraints is of paramount importance to mission-critical computer applications with hard real-time constraints. Because retransmission and coding techniques counteract the delay requirements, reliability may be achieved through replication over multiple fail-independent paths. Existing solutions, such as the parallel redundancy protocol (PRP), replicate all packets at the MAC layer over parallel paths. PRP works best in local area networks. However, it is not viable for IP networks that are a key element of emerging mission-critical systems. This limitation, coupled with diagnostic inability and lack of security, renders PRP unsuitable for reliable data-delivery in these IP networks. To address this issue, we present a transport-layer solution: the IP parallel redundancy protocol (iPRP). Designing iPRP poses non-trivial challenges in the form of selective packet replication, soft-state and multicast support. iPRP replicates only time-critical unicast or multicast UDP traffic. iPRP requires no modifications to the existing monitoring application, end-device operating system or to the intermediate network devices. It only requires a simple software installation on the end-devices. iPRP has a set of diagnostic tools for network debugging. With our implementation of iPRP in Linux, we show that iPRP supports multiple flows with minimal processing-and-delay overhead. It is being installed in our campus smart-grid network and is publicly available

Performance Assessment of Linear State Estimators Using Synchrophasor Measurements

This paper aims to assess the performance of linear state estimation (SE) processes of power systems relying on synchrophasor measurements. The performance assessment is conducted with respect to two different families of SE algorithms, i.e., static ones represented by weighted least squares (WLS) and recursive ones represented by Kalman filter (KF). To this end, this paper firstly recalls the analytical formulation of linearWLS state estimator (LWLS-SE) and Discrete KF state estimator (DKF-SE). We formally quantify the differences in the performance of the two algorithms. The validation of this result, together with the comprehensive performance evaluation of the considered state estimators, is carried out using two case studies, representing distribution (IEEE 123-bus test feeder) and transmission (IEEE 39-bus test system) networks. As a further contribution, this paper validates the correctness of the most common process model adopted in DKF-SE of power systems