scholarly journals On the robustness of three classes of rateless codes against pollution attacks in P2P networks

2021 ◽  
Author(s):  
Rossano Gaeta ◽  
Marco Grangetto
Keyword(s):  
Low Complexity ◽  
Rateless Codes ◽  
Fountain Codes ◽  
P2p Networks ◽  
Linear Network ◽  
Victim Selection ◽  
Additional Information ◽  
Pollution Attack ◽  
Pollution Attacks ◽  
Selection Of

AbstractRateless codes (a.k.a. fountain codes, digital fountain) have found their way in numerous peer-to-peer based applications although their robustness to the so called pollution attack has not been deeply investigated because they have been originally devised as a solution for dealing with block erasures and not for block modification. In this paper we provide an analysis of the intrinsic robustness of three rateless codes algorithms, i.e., random linear network codes (RLNC), Luby transform (LT), and band codes (BC) against intentional data modification. By intrinsic robustness we mean the ability of detecting as soon as possible that modification of at least one equation has occurred as well as the possibility a receiver can decode from the set of equations with and without the modified ones. We focus on bare rateless codes where no additional information is added to equations (e.g., tags) or higher level protocol are used (e.g., verification keys to pre-distribute to receivers) to detect and recover from data modification. We consider several scenarios that combine both random and targeted selection of equations to alter and modification of an equation that can either change the rank of the coding matrix or not. Our analysis reveals that a high percentage of attacks goes undetected unless a minimum code redundancy is achieved, LT codes are the most fragile in virtually all scenarios, RLNC and BC are quite insensitive to the victim selection and type of alteration of chosen equations and exhibit virtually identical robustness although BC offer a low complexity of the decoding algorithm.

scholarly journals A Secure Protocol against Selfish and Pollution Attacker Misbehavior in Clustered WSNs

Electronics ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1244
Author(s):  
Hana Rhim ◽  
Damien Sauveron ◽  
Ryma Abassi ◽  
Karim Tamine ◽  
Sihem Guemara
Keyword(s):  
Denial Of Service ◽  
Base Station ◽  
Hierarchical Organization ◽  
Secure Routing ◽  
Sensor Nodes ◽  
Dos Attacks ◽  
Linear Network ◽  
Secure Protocol ◽  
Misbehaving Nodes ◽  
Pollution Attacks

Wireless sensor networks (WSNs) have been widely used for applications in numerous fields. One of the main challenges is the limited energy resources when designing secure routing in such networks. Hierarchical organization of nodes in the network can make efficient use of their resources. In this case, a subset of nodes, the cluster heads (CHs), is entrusted with transmitting messages from cluster nodes to the base station (BS). However, the existence of selfish or pollution attacker nodes in the network causes data transmission failure and damages the network availability and integrity. Mainly, when critical nodes like CH nodes misbehave by refusing to forward data to the BS, by modifying data in transit or by injecting polluted data, the whole network becomes defective. This paper presents a secure protocol against selfish and pollution attacker misbehavior in clustered WSNs, known as (SSP). It aims to thwart both selfish and pollution attacker misbehaviors, the former being a form of a Denial of Service (DoS) attack. In addition, it maintains a level of confidentiality against eavesdroppers. Based on a random linear network coding (NC) technique, the protocol uses pre-loaded matrices within sensor nodes to conceive a larger number of new packets from a set of initial data packets, thus creating data redundancy. Then, it transmits them through separate paths to the BS. Furthermore, it detects misbehaving nodes among CHs and executes a punishment mechanism using a control counter. The security analysis and simulation results demonstrate that the proposed solution is not only capable of preventing and detecting DoS attacks as well as pollution attacks, but can also maintain scalable and stable routing for large networks. The protocol means 100% of messages are successfully recovered and received at the BS when the percentage of lost packets is around 20%. Moreover, when the number of misbehaving nodes executing pollution attacks reaches a certain threshold, SSP scores a reception rate of correctly reconstructed messages equal to 100%. If the SSP protocol is not applied, the rate of reception of correctly reconstructed messages is reduced by 90% at the same case.

scholarly journals Solidification Cracking Assessment of LTT Filler Materials by Means of Varestraint Testing and µCT

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2726
Author(s):  
Florian Vollert ◽  
Maximilian Thomas ◽  
Arne Kromm ◽  
Jens Gibmeier
Keyword(s):  
Crack Depth ◽  
Hot Cracking ◽  
Filler Materials ◽  
Crack Network ◽  
Additional Information ◽  
Model Following ◽  
Hot Crack ◽  
Maximum Crack ◽  
Material Volume ◽  
Selection Of

Investigations of the weldability of metals often deal with hot cracking, as one of the most dreaded imperfections during weld fabrication. The hot cracking investigations presented in this paper were carried out as part of a study on the development of low transformation temperature (LTT) weld filler materials. These alloys allow to mitigate tensile residual stresses that usually arise during welding using conventional weld filler materials. By this means, higher fatigue strength and higher lifetimes of the weld can be achieved. However, LTT weld filler materials are for example, high-alloyed Cr/Ni steels that are susceptible to the formation of hot cracks. To assess hot cracking, we applied the standardized modified varestraint transvarestraint hot cracking test (MVT), which is well appropriate to evaluate different base or filler materials with regard to their hot cracking susceptibility. In order to consider the complete material volume for the assessment of hot cracking, we additionally applied microfocus X-ray computer tomography (µCT). It is shown that by a suitable selection of welding and MVT parameter the analysis of the complete 3D hot crack network can provide additional information with regard to the hot cracking model following Prokhorov. It is now possible to determine easy accessible substitute values (e.g., maximum crack depth) for the extent of the Brittleness Temperature Range (BTR) and the minimum critical strain P m i n .

scholarly journals Transfer Incremental Learning Using Data Augmentation

2018 ◽  
Vol 8 (12) ◽  
pp. 2512 ◽  
Author(s):  
Ghouthi Boukli Hacene ◽  
Vincent Gripon ◽  
Nicolas Farrugia ◽  
Matthieu Arzel ◽  
Michel Jezequel
Keyword(s):  
Incremental Learning ◽  
Deep Neural Networks ◽  
Data Augmentation ◽  
State Of The Art ◽  
Low Complexity ◽  
Computational Power ◽  
Learning Problem ◽  
Learning Techniques ◽  
Using Data ◽  
Selection Of

Deep learning-based methods have reached state of the art performances, relying on a large quantity of available data and computational power. Such methods still remain highly inappropriate when facing a major open machine learning problem, which consists of learning incrementally new classes and examples over time. Combining the outstanding performances of Deep Neural Networks (DNNs) with the flexibility of incremental learning techniques is a promising venue of research. In this contribution, we introduce Transfer Incremental Learning using Data Augmentation (TILDA). TILDA is based on pre-trained DNNs as feature extractors, robust selection of feature vectors in subspaces using a nearest-class-mean based technique, majority votes and data augmentation at both the training and the prediction stages. Experiments on challenging vision datasets demonstrate the ability of the proposed method for low complexity incremental learning, while achieving significantly better accuracy than existing incremental counterparts.

Marketing Literature Review

2000 ◽  
Vol 64 (3) ◽  
pp. 102-114
Author(s):  
Myron Leonard
Keyword(s):  
Literature Review ◽  
Database Marketing ◽  
Marketing Literature ◽  
Additional Information ◽  
Ann Arbor ◽  
Literature Database ◽  
Selection Of

This section is based on a selection of article abstracts from a comprehensive business literature database. Marketing-related abstracts from over 125 journals (both academic and trade) are reviewed by JM staff. Descriptors for each entry are assigned by JM staff. Each issue of this section represents three months of entries into the database. JM thanks UMI for use of the ABI/INFORM business database. Each entry has an identifying number. Cross-references appear immediately under each subject heading. The following article abstracts are available online from the ABI/INFORM database, which is published and copyrighted by UMI. For additional information about access to the database or about obtaining photocopies of the articles abstracted here, please call (800) 626-2823 or write to UMI, 300 N. Zeeb Rd., Ann Arbor, MI 48106.

Soil gas physical-chemistry survey for geothermal exploration at Terceira Island, Azores.

2020 ◽  
Author(s):  
Claudia Rodríguez-Pérez ◽  
Alba Martín-Lorenzo ◽  
Fátima Rodríguez ◽  
Gladys V. Melián ◽  
María Asensio-Ramos ◽  
...  
Keyword(s):  
Hydrothermal Activity ◽  
Soil Gas ◽  
Volcanic Complex ◽  
Additional Information ◽  
Geothermal Potential ◽  
Potential Success ◽  
Exploratory Wells ◽  
To Receive ◽  
Selection Of

<p>Terceira Island is located in the Azores Archipelago and it lies at the intersection of four submarine volcanic ridges. Due to its characteristics the geothermal potential of Terceira Island has begun to receive some interest from researchers and decision makers from the 70s of last century, but only in 2000 an exploration license was granted in favour of GEOTERCEIRA (now EDA RENOVÁVEIS S.A.). The area of this license is located in the central part of the island in the Pico Alto Volcanic Complex, and includes the fumarolic field of Furnas do Enxofre.</p><p>The main aim of this study is to provide additional information about the presence of fluids upflow regions and areas of increased subsurface permeability related to high temperature hydrothermal activity at depth, as part of an study to expand the current geothermal plant of Terceira. To achieve this objective, a soil gas and diffuse CO<sub>2</sub> and H<sub>2</sub>S degassing survey, which included in situ CO<sub>2</sub> emission measurements and soil temperature at 15 and 40 cm deep and the collection of soil gas samples, was performed during September 2019. 122 sampling sites were selected spaced at ~100 meters at Pico Alto Volcanic Complex. Diffuse CO<sub>2</sub> and H<sub>2</sub>S measurements were performed according to the accumulation chamber method, using a non-dispersive infrared (NDIR) LICOR-830 CO<sub>2</sub> analyser and ALPHASENSE H<sub>2</sub>S-BH detectors, respectively. In addition, soil gas samples were collected to analyse the He, H<sub>2</sub>, O<sub>2</sub>, N<sub>2</sub>, CO<sub>2</sub>, CH<sub>4</sub> and CO contents and the isotopic composition of the CO<sub>2</sub>. Soil CO<sub>2</sub> efflux values ranged between non-detectable values and 56.2 g m<sup>2</sup> d<sup>-1</sup>, with an average of 21.7 g m<sup>2</sup> d<sup>-1</sup>. Soil H<sub>2</sub>S efflux values ranged between non-detectable values and 0.245 g m<sup>2</sup> d<sup>-1</sup>, with an average of 0.027 g m<sup>2</sup> d<sup>-1</sup>. The probability plot technique applied to the soil CO<sub>2</sub> efflux data allowed to distinguish three different geochemical populations: background, intermediate and peak represented by 36.9 %, 59.8 % and 3.3 % respectively, with geometric means of 10.8, 25.4 and 50.0 g m<sup>2</sup> d<sup>-1</sup> respectively. The spatial distribution of soil CO<sub>2</sub> efflux data, constructed by means of Sequential Gaussian simulations algorithm, depicted the most important emission anomalies at the western section of the study area. These results can help to identify the possible existence of additional actively degassing geothermal reservoirs to reduce the uncertainty inherent to the selection of the area with the highest potential success in the selection of new exploratory wells at Terceira.</p>

Problems of Optimum Selection

1968 ◽  
Vol 27 (3) ◽  
pp. 715-720
Author(s):  
Gail O'Connor
Keyword(s):  
Factor Analysis ◽  
Multiple Regression ◽  
Sources Of Information ◽  
Additional Information ◽  
Factor Analytic ◽  
Optimum Selection ◽  
Mechanical Ability ◽  
Different Sources ◽  
Selection Of ◽  
Predictive Efficiency

This study examined the selection of different sources of information made by multiple regression, cutting scores, and factor analytic techniques and investigated these procedures in terms of their comparable predictive efficiency. Prior to their job training, 220 Naval winch operator trainees took a battery of seven McQuarrie subtests for mechanical ability. Criterion scores were derived from ratings given subsequent to training. No differences were found among the three methods. However, it is pointed out that the judicious use of factor analysis can provide additional information about the relationships and complexities of the predictors and criterion not available through multiple regression or cutting scores.

Marketing Literature Review

2000 ◽  
Vol 64 (2) ◽  
pp. 109-121
Author(s):  
Myron Leonard
Keyword(s):  
Literature Review ◽  
Database Marketing ◽  
Marketing Literature ◽  
Additional Information ◽  
Ann Arbor ◽  
Literature Database ◽  
Selection Of

This section is based on a selection of article abstracts from a comprehensive business literature database. Marketing-related abstracts from over 125 journals (both academic and trade) are reviewed by JM staff. Descriptors for each entry are assigned by JM staff. Each issue of this section represents three months of entries into the database. JM thanks UMI for use of the ABI/INFORM business database. Each entry has an identifying number. Cross-references appear immediately under each subject heading. The following article abstracts are available online from the ABI/INFORM database, which is published and copyrighted by UMI. For additional information about access to the database or about obtaining photocopies of the articles abstracted here, please call (800) 626-2823 or write to UMI, 300 N. Zeeb Rd., Ann Arbor, MI 48106.

scholarly journals Learning to Play Using Low-Complexity Rule-Based Policies: Illustrations through Ms. Pac-Man

2007 ◽  
Vol 30 ◽  
pp. 659-684 ◽  
Author(s):  
I. Szita ◽  
A. Lorincz
Keyword(s):  
Low Complexity ◽  
Entropy Method ◽  
Cross Entropy ◽  
Rule Based ◽  
Learning Tasks ◽  
Large Pool ◽  
Cross Entropy Method ◽  
High Level ◽  
Selection Of ◽  
Better Than

In this article we propose a method that can deal with certain combinatorial reinforcement learning tasks. We demonstrate the approach in the popular Ms. Pac-Man game. We define a set of high-level observation and action modules, from which rule-based policies are constructed automatically. In these policies, actions are temporally extended, and may work concurrently. The policy of the agent is encoded by a compact decision list. The components of the list are selected from a large pool of rules, which can be either hand-crafted or generated automatically. A suitable selection of rules is learnt by the cross-entropy method, a recent global optimization algorithm that fits our framework smoothly. Cross-entropy-optimized policies perform better than our hand-crafted policy, and reach the score of average human players. We argue that learning is successful mainly because (i) policies may apply concurrent actions and thus the policy space is sufficiently rich, (ii) the search is biased towards low-complexity policies and therefore, solutions with a compact description can be found quickly if they exist.

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