scholarly journals A refinement-based development of a distributed signalling system

2021 ◽  
Author(s):  
Paulius Stankaitis ◽  
Alexei Iliasov ◽  
Tsutomu Kobayashi ◽  
Yamine Aït-Ameur ◽  
Fuyuki Ishikawa ◽  
...  
Keyword(s):  
Model Verification ◽  
Modelling Language ◽  
Distributed Protocol ◽  
Rigorous Approach ◽  
Railway Systems ◽  
Main Challenge ◽  
Stepwise Development ◽  
Railway Signalling ◽  
High Level ◽  
Signalling Systems

AbstractThe decentralised railway signalling systems have a potential to increase capacity, availability and reduce maintenance costs of railway networks. However, given the safety-critical nature of railway signalling and the complexity of novel distributed signalling solutions, their safety should be guaranteed by using thorough system validation methods. To achieve such a high-level of safety assurance of these complex signalling systems, scenario-based testing methods are far from being sufficient despite that they are still widely used in the industry. Formal verification is an alternative approach which provides a rigorous approach to verifying complex systems and has been successfully used in the railway domain. Despite the successes, little work has been done in applying formal methods for distributed railway systems. In our research we are working towards a multifaceted formal development methodology of complex railway signalling systems. The methodology is based on the Event-B modelling language which provides an expressive modelling language, a stepwise development and a proof-based model verification. In this paper, we present the application of the methodology for the development and verification of a distributed protocol for reservation of railway sections. The main challenge of this work is developing a distributed protocol which ensures safety and liveness of the distributed railway system when message delays are allowed in the model.

Selected issues of risk assessment in relation to railway signalling systems

2019 ◽  
Vol 127 ◽  
pp. 81-91
Author(s):  
Dariusz Szmel ◽  
Wiesław Zabłocki ◽  
Przemysław Ilczuk ◽  
Andrzej Kochan
Keyword(s):  
Risk Assessment ◽  
Hazard Analysis ◽  
Holistic Approach ◽  
Hazard Identification ◽  
Computer Application ◽  
Requirements Definition ◽  
Railway Systems ◽  
Railway System ◽  
Railway Signalling ◽  
High Level

The selected methods of the risk assessment and analysis of signaling railway systems about the whole railway system were introduced in the article. The selected methods applied at the first stage of safety requirements definition within the preliminary system definition described at a high level of abstraction will be considered. It will be discussed the application of a holistic approach with the management of residual risk. The risk models will be presented and steps of assessing, analyzing, and evaluating risk, including hazard identification, consequences analysis, and selection of risk acceptance principles. The article's key aspect will be the determination of quantitative safety targets based on the THR indicator as an important parameter for further hazard analysis of the system, particularly in computer application. Normative and legislation requirements in the scope of risk assessment for the railway system will be considered, including the interoperability and safety directives and decrees regulations.

scholarly journals Selective Cytotoxicity of Piperine over Multidrug Resistance Leukemic Cells

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 934
Author(s):  
Julia Quarti ◽  
Daianne N. M. Torres ◽  
Erika Ferreira ◽  
Raphael S. Vidal ◽  
Fabiana Casanova ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Black Pepper ◽  
Leukemic Cells ◽  
Glycoprotein P ◽  
Cytotoxic Effects ◽  
Collateral Sensitivity ◽  
Main Challenge ◽  
Independent Mechanism ◽  
High Level ◽  
Parp 1

Multidrug resistance (MDR) is the main challenge in the treatment of chronic myeloid leukemia (CML), and P-glycoprotein (P-gp) overexpression is an important mechanism involved in this resistance process. However, some compounds can selectively affect MDR cells, inducing collateral sensitivity (CS), which may be dependent on P-gp. The aim of this study was to investigate the effect of piperine, a phytochemical from black pepper, on CS induction in CML MDR cells, and the mechanisms involved. The results indicate that piperine induced CS, being more cytotoxic to K562-derived MDR cells (Lucena-1 and FEPS) than to K562, the parental CML cell. CS was confirmed by analysis of cell metabolic activity and viability, cell morphology and apoptosis. P-gp was partially required for CS induction. To investigate a P-gp independent mechanism, we analyzed the possibility that poly (ADP-ribose) polymerase-1 (PARP-1) could be involved in piperine cytotoxic effects. It was previously shown that only MDR FEPS cells present a high level of 24 kDa fragment of PARP-1, which could protect these cells against cell death. In the present study, piperine was able to decrease the 24 kDa fragment of PARP-1 in MDR FEPS cells. We conclude that piperine targets selectively MDR cells, inducing CS, through a mechanism that might be dependent or not on P-gp.

scholarly journals Modular action language

2015 ◽  
Vol 16 (2) ◽  
pp. 189-235 ◽  
Author(s):  
DANIELA INCLEZAN ◽  
MICHAEL GELFOND
Keyword(s):  
Logic Programming ◽  
Medium Size ◽  
Programming System ◽  
Problem Structuring ◽  
System Description ◽  
Action Languages ◽  
Special Cases ◽  
Action Language ◽  
Stepwise Development ◽  
High Level

AbstractThe paper introduces a new modular action language,${\mathcal ALM}$, and illustrates the methodology of its use. It is based on the approach of Gelfond and Lifschitz (1993,Journal of Logic Programming 17, 2–4, 301–321; 1998,Electronic Transactions on AI 3, 16, 193–210) in which a high-level action language is used as a front end for a logic programming system description. The resulting logic programming representation is used to perform various computational tasks. The methodology based on existing action languages works well for small and even medium size systems, but is not meant to deal with larger systems that requirestructuring of knowledge.$\mathcal{ALM}$is meant to remedy this problem. Structuring of knowledge in${\mathcal ALM}$is supported by the concepts ofmodule(a formal description of a specific piece of knowledge packaged as a unit),module hierarchy, andlibrary, and by the division of a system description of${\mathcal ALM}$into two parts:theoryandstructure. Atheoryconsists of one or more modules with a common theme, possibly organized into a module hierarchy based on adependency relation. It contains declarations of sorts, attributes, and properties of the domain together with axioms describing them.Structuresare used to describe the domain's objects. These features, together with the means for defining classes of a domain as special cases of previously defined ones, facilitate the stepwise development, testing, and readability of a knowledge base, as well as the creation of knowledge representation libraries.

scholarly journals ALGORITHM FOR TASK CONSOLIDATION IN CLOUD COMPUTING: A COMPARATIVE SURVEY

2018 ◽  
Vol 6 (5) ◽  
pp. 340-345
Author(s):  
Rajat Pugaliya ◽  
Madhu B R
Keyword(s):  
Cloud Computing ◽  
Energy Consumption ◽  
Resource Utilization ◽  
Service Provider ◽  
Virtual Machines ◽  
Cloud Service ◽  
Cloud Service Provider ◽  
Dynamic Task ◽  
Main Challenge ◽  
High Level

Cloud Computing is an emerging field in the IT industry. Cloud computing provides computing services over the Internet. Cloud Computing demand increasing drastically, which has enforced cloud service provider to ensure proper resource utilization with less cost and less energy consumption. In recent time various consolidation problems found in cloud computing like the task, VM, and server consolidation. These consolidation problems become challenging for resource utilization in cloud computing. We found in the literature review that there is a high level of coupling in resource utilization, cost, and energy consumption. The main challenge for cloud service provider is to maximize the resource utilization, reduce the cost and minimize the energy consumption. The dynamic task consolidation of virtual machines can be a way to solve the problem. This paper presents the comparative study of various task consolidation algorithms.

IT-Security in Railway Signalling Systems

2014 ◽  
pp. 56-64
Author(s):  
Christian Schlehuber ◽  
Erik Tews ◽  
Stefan Katzenbeisser
Keyword(s):  
It Security ◽  
Railway Signalling ◽  
Signalling Systems

New light on the Anglo-Saxon succession: two cemeteries and their dates

Antiquity ◽  
2009 ◽  
Vol 83 (322) ◽  
pp. 1096-1108 ◽  
Author(s):  
C.M. Hills ◽  
T.C. O'Connell
Keyword(s):  
Stable Isotopes ◽  
Fifth Century ◽  
Interesting Problem ◽  
Anglo Saxon ◽  
Rigorous Approach ◽  
High Level ◽  
Very High

The origin of the English is an interesting problem – and not only for them. In one short century, the evidence from texts, burial, artefacts, stable isotopes and now DNA provides several different answers to the question of whether England was invaded by Germans in the fifth century and if so in what manner. The rigorous approach by our authors tips the balance back in favour of a population changing its cultural allegiance – rather than being physically overwhelmed – but, as they emphasise, any new reading must depend on a very high level of archaeological precision – perhaps only now coming within reach.

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