Security analysis of wireless mesh backhauls for mobile networks

Radio links are used to provide backhaul connectivity for base stations of mobile networks, in cases in which cable-based alternatives are not available and cannot be deployed in an economic or timely manner. While such wireless backhauls have been predominantly used in redundant tree and ring topologies in the past, mobile network operators have become increasingly interested in meshed topologies for carrier-grade wireless backhauls. However, wireless mesh backhauls are potentially more susceptible to security vulnerabilities, given that radio links are more exposed to tampering and given their higher system complexity. This article extends prior security threat analyses of 3rd generation mobile network architectures for the case of wireless mesh backhauls. It presents a description of the security model for the considered architecture and provides a list of the basic assumptions, security objectives, assets to be protected and actors of the analysis. On this foundation, potential security threats are analyzed and discussed and then assessed for their corresponding risk. The result of this risk assessment is then used to define a set of security requirements. Finally, we give some recommendations for wireless mesh backhaul designs and implementations following these requirements.European Community's Seventh Framework ProgramPublicad

До питання про особливості методу правового регулювання відностин у сфері державних закупівель

В статті розглянуто особливості методу правового регулювання відносин у сфері державних закупівель, здійснено аналіз науково-теоретичної розробки цього питання, окреслено основні актуальні на сьогоднішній день проблемні моменти, які стримують розвиток та вдосконалення державних закупівель,, сформульовано основні напрямки розвитку подальших досліджень формування концепції методу правового регулювання відносин у галузі державних закупівель. Ключові слова: державні закупівлі, тендер, метод правового регулювання.В статье рассмотрены особенности метода правового регулирования отношений в сфере государственных закупок, осуществлено анализ научно-теоретической разработки этого вопроса, очерчено основные актуальные на сегодняшний день проблемные моменты, которые сдерживают развитие и усовершенствование государственных закупок, сформулировано основные направления развития дальнейших исследований формирования концепции метода правового регулирования отношений в отрасли государственных закупок. Ключевые слова: государственные закупки, тендер, метод правового регулирования.The article highlights the peculiarities of the legal regulation method of state purchases; analysis of theoretical examination of this issue. The author outlines a string of problems which restrain development and improvement of procurement; states direction of further research of the legal regulation method of state purchases conception. Key words: state procurement, tender, legal regulation method

Cognitively diagnostic analysis using the G-DINA model in R

Cognitive diagnosis models (CDMs) have increasingly been applied in education and other fields. This article provides an overview of a widely used CDM, namely, the G-DINA model, and demonstrates a hands-on example of using multiple R packages for a series of CDM analyses. This overview involves a step-by-step illustration and explanation of performing Q-matrix evaluation, CDM calibration, model fit evaluation, item diagnosticity investigation, classification reliability examination, and the result presentation and visualization. Some limitations of conducting CDM analysis in R are also discusse

Supporting Carrier Grade Services over Wireless Mesh Networks: the approach of the European FP-7 STREP CARMEN

CARMEN is a three-year Specific Targeted Research Project (STREP) funded by the European Commission within the 7th Framework Program. The CARMEN access network will complement existing access technologies by exploiting low cost mesh networking techniques, thus minimizing deployment and maintenance costs. The CARMEN architecture introduces an abstraction layer that hides the specifics of the underlying access technology providing an abstract interface on top of which higher layers can be easily developed. This allows for the integration of current and future heterogeneous wireless technologies to provide scalable and efficient mobile ubiquitous Internet access, able to adapt to different environments and user requirements. Following these goals, CARMEN aims to define, study and implement link and technology abstractions, mobility support, and quality of service. The architecture also includes advanced monitoring features that allow for dynamic self-configuration, thereby reducing the installation and operational costs.European Community's Seventh Framework ProgramPublicad

Загальний перелік сіл/сільрад та колгоспів Української СРР, занесених на “чорну дошку” в 1932–1933 роках

Перелік підготовлено Георгієм Папакіним та Оленою Лісняк за відомостями, наданими обласними державними адміністраціями України

Differential Item Functioning in PISA Due to Mode Effects

One of the most important goals of the Programme for International Student Assessment (PISA) is assessing national changes in educational performance over time. These so-called trend results inform policy makers about the development of ability of 15-year-old students within a specific country. The validity of those trend results prescribes invariant test conditions. In the 2015 PISA survey, several alterations to the test administration were implemented, including a switch from paper-based assessments to computer-based assessments for most countries (OECD 2016a). This alteration of the assessment mode is examined by evaluating if the items used to assess trends are subject to differential item functioning across PISA surveys (2012 vs. 2015). Furthermore, the impact on the trend results due to the change in assessment mode of the Netherlands is assessed. The results show that the decrease reported for mathematics in the Netherlands is smaller when results are based upon a separate national calibration.</p

Технология проведения капитального ремонта резервной нитки подводного перехода магистрального газопровода в условиях Западной Сибири

Объектом иccледования являетcя резервная нитка через р. Обь на учаcтке газопровода. Цель работы – изучить и провеcти анализ технологий капитального ремонта резервной нитки подводного перехода в уcловиях Западной Cибири, а также выбор наиболее актуального технологичеcкого решения в cлучаях возникновения аварийных cитуаций. В процеccе иccледования проводилиcь раcчеты по определению толщины cтенки трубопровода, баллаcтировке трубопровода, проверка прочноcти и уcтойчивоcти, проверка на недопуcтимые плаcтичеcкие деформации.The object of the study is the reserve thread across the p. Ob at the site of the gas pipeline. The purpose of the work is to study and analyze the technologies of overhaul of the reserve thread of the underwater passage in Western Siberia, as well as the selection of the most relevant technological solution in the event of emergency situations. In the course of the study, calculations were carried out to determine the thickness of the wall of the pipeline, to balance the pipeline, to check the strength and stability, and to check for unacceptable plastic deformations

A hierarchical latent response model for inferences about examinee engagement in terms of guessing and item‐level non‐response

In low‐stakes assessments, test performance has few or no consequences for examinees themselves, so that examinees may not be fully engaged when answering the items. Instead of engaging in solution behaviour, disengaged examinees might randomly guess or generate no response at all. When ignored, examinee disengagement poses a severe threat to the validity of results obtained from low‐stakes assessments. Statistical modelling approaches in educational measurement have been proposed that account for non‐response or for guessing, but do not consider both types of disengaged behaviour simultaneously. We bring together research on modelling examinee engagement and research on missing values and present a hierarchical latent response model for identifying and modelling the processes associated with examinee disengagement jointly with the processes associated with engaged responses. To that end, we employ a mixture model that identifies disengagement at the item‐by‐examinee level by assuming different data‐generating processes underlying item responses and omissions, respectively, as well as response times associated with engaged and disengaged behaviour. By modelling examinee engagement with a latent response framework, the model allows assessing how examinee engagement relates to ability and speed as well as to identify items that are likely to evoke disengaged test‐taking behaviour. An illustration of the model by means of an application to real data is presented