Analysis of Trade-offs in Fault-Tolerant Distributed Computing and Replicated Databases

This paper examines fundamental trade-offs in fault-tolerant distributed systems and replicated databases built over the Internet. We discuss interplays between consistency, availability, and latency which are in the very nature of globally distributed computer systems and also analyse their interconnection with durability and energy efficiency. In this paper we put forward an idea that consistency, availability, latency, durability and other properties need to be viewed as more continuous than binary in contrast to the well-known CAP/PACELC theorems. We compare different consistency models and highlight the role of the application timeout, replication factor and other settings that essentially determine the interplay between above properties. Our findings may be of interest to software engineers and system architects who develop Internet-scale distributed computer systems and cloud solutions

From Analysing Operating System Vulnerabilities to Designing Multiversion Intrusion-Tolerant Architectures

This paper analyses security problems of modern computer systems caused by vulnerabilities in their operating systems. Our scrutiny of widely used enterprise operating systems focuses on their vulnerabilities by examining the statistical data available on how vulnerabilities in these systems are disclosed and eliminated, and by assessing their criticality. This is done by using statistics from both the National Vulnerabilities database (NVD) and the Common Vulnerabilities and Exposures system (CVE). The specific technical areas the paper covers are the quantitative assessment of forever-day vulnerabilities, estimation of days-of-grey-risk, the analysis of the vulnerabilities severity and their distributions by attack vector and impact on security properties. In addition, the study aims to explore those vulnerabilities that have been found across a diverse range of operating systems. This leads us to analysing how different intrusion-tolerant architectures deploying the operating system diversity impact availability, integrity and confidentiality

Prospects of development of the specialty «Vocational training (service)»

The article deals with one of the promising areas of development of the training direction "Vocational training" on the example of the profile "Service", which consists in advanced training of teachers of vocational training in the field of image technologies in the fashion and beauty industryВ статье рассматривается одно из перспективных направлений развития направления подготовки «Профессиональное обучение» на примере профиля «Сервис», заключающееся в опережающей подготовке педагогов профессионального обучения в области технологий имиджа в индустрии моды и красот

Worldskills is the purpose of improving the preparation, professional learning pedagogue in design style and image

The article deals with the main directions of improving the training of teachers of vocational training in modern conditions. One of the necessary conditions is to take into account international requirements for training in working professions and specialties of secondary vocational educationВ статье рассматриваются основные направления совершенствования подготовки педагогов профессионального обучения в современных условиях. Одно из необходимых условий – учет международных требований к подготовке по рабочим профессиям и специальностям среднего профессионального образовани

Exploring Timeout As A Performance And Availability Factor Of Distributed Replicated Database Systems

A concept of distributed replicated data storages like Cassandra, HBase, MongoDB has been proposed to effectively manage the Big Data sets whose volume, velocity, and variability are difficult to deal with by using the traditional Relational Database Management Systems. Trade-offs between consistency, availability, partition tolerance, and latency are intrinsic to such systems. Although relations between these properties have been previously identified by the well-known CAP theorem in qualitative terms, it is still necessary to quantify how different consistency and timeout settings affect system latency. The paper reports results of Cassandra's performance evaluation using the YCSB benchmark and experimentally demonstrates how to read latency depends on the consistency settings and the current database workload. These results clearly show that stronger data consistency increases system latency, which is in line with the qualitative implication of the CAP theorem. Moreover, Cassandra latency and its variation considerably depend on the system workload. The distributed nature of such a system does not always guarantee that the client receives a response from the database within a finite time. If this happens, it causes so-called timing failures when the response is received too late or is not received at all. In the paper, we also consider the role of the application timeout which is the fundamental part of all distributed fault tolerance mechanisms working over the Internet and used as the main error detection mechanism here. The role of the application timeout as the main determinant in the interplay between system availability and responsiveness is also examined in the paper. It is quantitatively shown how different timeout settings could affect system availability and the average servicing and waiting time. Although many modern distributed systems including Cassandra use static timeouts it was shown that the most promising approach is to set timeouts dynamically at run time to balance performance, availability and improve the efficiency of the fault-tolerance mechanisms

Interpreting of the economic effectiveness of conveyors used for transporting seeds along the curvilinear tracks

Запропоновано методику техніко-економічного обґрунтування транспортно-технологічних механізмів (ТТМ), що проводиться на основі їх порівняльного оцінювання з типовими представниками машин, які здійснюють однотипні операції й несуттєво відрізняються за основними параметрами. Наведено аналітичні залежності для визначення основних складових техніко-економічного оцінювання, зокрема принципи економічного розрахунку собівартості виготовлення та експлуатації ТТМ і їх елементів та економічної ефективності оцінювання нових конструкцій ТТМ.The main operating and loading-unloading members of most agricultural machines are their screw operating members. Their position in the transporting means is in general between 40-50% according to different sources. Their characteristic feature is that, caused by different rheological properties of cargo, which specify the nomenclature and design parameters of screws. The advantages of screw conveyors are their being easily designed and maintained, small overall dimensions loading and unloading convenience, their geometry, etc. Their disadvantages are high specific power consumption, sufficient cargo crashing and grinding, screw operating member and casing wear and their being sensible to the overloading, which result in creation of cargo blocking inside the casing. In spite of the fact, that the scientific papers on the screw conveyors design are available, modern requirements of the agricultural production need improvement of the available constructions and creation of totally new ones, which require certain theoretical and experimental investigations with their further technological-economic interpreting. The method of technical-economic interpreting of transporting-technological mechanisms (TTM), carried out on their comparative estimation with the conventional ones, which perform the same type operations and do not differ sufficiently in to their main operations, has been proposed in the article. Analytical dependencies for determination of main components of the technological-economic estimation, the principle of economic calculation of the manufacturing cost price, TTM and their components maintenance and operation as well as economic effectiveness of the new TTM construction estimation in particular, have been deduced. The application of the tubular scraper cable conveyor for transporting seeds along the curvilinear tracks as compared with the flexible screw conveyor and flexible pneumatic conveyor was found to be very effective and makes the process be more qualitative, decrease the effect on seeds and minimize their injury

Main directions of improving the system of additional professional education for specialistsrailway transport

In the article, conclusions about the current state and the needs of additional vocational education for railway workers.Directions of perfection of professional training for heads and experts of railway transportation are definedОпределены современное состояние и потребности дополнительного профессионального образования для работников железнодорожного транспорта. Обозначены направления совершенствования профессиональной подготовки руководителей и специалистов железнодорожного транспорт

Professional standard – peg professional work of teachers professional training

This article discusses the relevance of the development and implementation of the professional standard of vocational training of the teacher, its significance, characteristics and procedure for the development and use opportunitiesРассматриваются актуальность разработки и внедрения профессионального стандарта педагога профессионального обучения, его значимость, особенности и процедура разработки, а также возможности использовани

Integration of competence-oriented tasks during preparing of bachelors in technical universities

The article describes the design process of formalized tasks for students of technical universities, directed on fostering their professional competence descriptors, corresponding to the occupational activities of graduatesРассмотрен процесс проектирования формализованных задач, направленных на формирование у студентов дескрипторов профессиональных компетенций, соответствующих видам профессиональной деятельности выпускник