scholarly journals Graphic modeling in Distributed Autonomous and Asynchronous Automata (DA3)

2021 ◽  
Author(s):  
Wiktor B. Daszczuk
Keyword(s):  
Distributed Systems ◽  
Formal Verification ◽  
Graphical Simulation ◽  
Distributed Components ◽  
Distributed Computations ◽  
Asynchronous Automata ◽  
Graphic Modeling ◽  
Late Stages ◽  
Natural Characteristics ◽  
Insight Into

AbstractAutomated verification of distributed systems becomes very important in distributed computing. The graphical insight into the system in the early and late stages of the project is essential. In the design phase, the visual input helps to articulate the collaborative distributed components clearly. The formal verification gives evidence of correctness or malfunction, but in the latter case, graphical simulation of counterexample helps for better understanding design errors. For these purposes, we invented Distributed Autonomous and Asynchronous Automata (DA3), which have the same semantics as the formal verification base—Integrated Model of Distributed Systems (IMDS). The IMDS model reflects the natural characteristics of distributed systems: unicasting, locality, autonomy, and asynchrony. Distributed automata have all of these features because they share the same semantics as IMDS. In formalism, the unified system definition has two views: the server view of the cooperating distributed nodes and the agent view of the migrating agents performing distributed computations. The automata have two formally equivalent forms that reflect two views: Server DA3 for observing servers exchanging messages, and Agent DA3 for tracking agents, which visit individual servers in their progress of distributed calculations. We present the DA3 formulation based on the IMDS formalism and their application to design and verify distributed systems in the Dedan environment. DA3 formalism is compared with other concepts of distributed automata known from the literature.

scholarly journals Modelling Distributed Systems in Distributed Autonomous and Asynchronous Automata (DA3)

2019 ◽  
Author(s):  
Wiktor Daszczuk
Keyword(s):  
Distributed Systems ◽  
Structural Analysis ◽  
Distributed System ◽  
System Configuration ◽  
Graphical Modeling ◽  
Global System ◽  
Equivalent Models ◽  
Distributed Components ◽  
System Components ◽  
Asynchronous Automata

Integrated Model of Distributed Systems is used for modeling and verification. In formalism, the distributed system is modeled as a collection of server states and agent messages. The evolution of the system takes the form of actions that transform the global system configuration (states and messages) into a new configuration. Formalism is used in the Dedan verification environment for finding different kinds of deadlocks: communication deadlocks in the server view and resource deadlocks in the agent view. For other purposes, a conversion has been developed to equivalent models: to Petri nets for structural analysis and do Distributed Autonomous and Asynchronous Automata (DA3) for easy graphical modeling in terms of system components. In addition, it is possible to simulate a verified system on distributed components in DA3. The automata have two forms: Server-DA3 (S-DA3) for the server view and Agent-DA3 (A-DA3) for the agent view. DA3 formalism is compared to other concepts of distributed automata known from the literature.

scholarly journals The Endothelium and Its Role in Regulating Vascular Tone

2010 ◽  
Vol 4 (1) ◽  
pp. 302-312 ◽  
Author(s):  
Aamer Sandoo ◽  
Jet J.C.S Veldhuijzen van Zanten ◽  
George S Metsios ◽  
Douglas Carroll ◽  
George D Kitas
Keyword(s):  
Endothelial Cell ◽  
Vascular Function ◽  
Cell Physiology ◽  
Non Invasive ◽  
Vasoactive Factors ◽  
And Function ◽  
Complementary Actions ◽  
Late Stages ◽  
Insight Into ◽  
Clinical Populations

The endothelium forms an important part of the vasculature and is involved in promoting an atheroprotective environment via the complementary actions of endothelial cell-derived vasoactive factors. Disruption of vascular homeostasis can lead to the development of endothelial dysfunction which in turn contributes to the early and late stages of atherosclerosis. In recent years an increasing number of non-invasive vascular tests have been developed to assess vascular structure and function in different clinical populations. The present review aims to provide an insight into the anatomy of the vasculature as well as the underlying endothelial cell physiology. In addition, an in-depth overview of the current methods used to assess vascular function and structure is provided as well as their link to certain clinical populations.

scholarly journals The use of principal component analysis for the construction of the Water Poverty Index

RBRH ◽  
2019 ◽  
Vol 24 ◽  
Author(s):  
Larynne Dantas de Senna ◽  
Adelena Gonçalves Maia ◽  
Joana Darc Freire de Medeiros
Keyword(s):  
Principal Component Analysis ◽  
Poverty Reduction ◽  
Principal Component ◽  
Component Analysis ◽  
Poverty Index ◽  
Multiple Dimensions ◽  
Water Poverty Index ◽  
Clear Identification ◽  
Natural Characteristics ◽  
Insight Into

ABSTRACT In relation to water resources, indexes can be created to express the multiple dimensions involved with it to aid the planning and management of basins. In this regard, the Water Poverty Index is globally used, but one of its criticisms includes the subjectivity associated with how the sub-indexes are weighted. Therefore, in this study, we applied principal component analysis (PCA) to determine the sub-indexes’ weight: resource, access, capacity, use, and environment of the Seridó river basin. This new index with PCA presents an average range with broader values compared to methodologies without, allowing clear identification of the disparities among the cities and the possibility to better prioritize investments concerning water poverty reduction. Our results show that this approach makes it possible to qualitatively identify geographical locations that have greater water poverty compared to others. Additionally, with this approach, it can be determined whether water poverty is caused due to natural characteristics or deficits in water infrastructure investment, providing insight into social fragilities as well. Overall, the presented hierarchical tool in this study has a high value to improve the planning of water resource uses.

INCREMENTAL TRANSITIVE DEPENDENCY TRACKING IN DISTRIBUTED COMPUTATIONS

1996 ◽  
Vol 06 (03) ◽  
pp. 427-435 ◽  
Author(s):  
CLAUDE JARD ◽  
GUY-VINCENT JOURDAN
Keyword(s):  
Distributed Systems ◽  
Arbitrary Subset ◽  
Causal Dependency ◽  
Tracking Technique ◽  
Distributed Computations ◽  
Dependency Tracking ◽  
Observable Event ◽  
Direct Dependency

The notion of causal dependency between events in distributed systems plays a central role in reasoning about distributed program behaviours [14]. Different techniques have been designed to track these dependencies during execution. We suggest a new incremental transitive dependency tracking technique. Once the transitive dependencies are recorded for an observable event, the dependency tracking cost can be reduced by propagating only future dependencies beyond that event. Furthermore, in contrast with the direct dependency tracking technique already proposed in the literature, our technique allows to compute the dependencies among an arbitrary subset of observable events. This gives an interesting filtering capability.

scholarly journals Evidence for Stellar Evolution in Mira Variables

1998 ◽  
Vol 11 (1) ◽  
pp. 356-356
Author(s):  
Patricia A Whitelock
Keyword(s):  
Mass Loss ◽  
Real Time ◽  
Time Evolution ◽  
Stellar Evolution ◽  
Evolutionary Status ◽  
Late Type ◽  
Chemical Changes ◽  
Mira Variables ◽  
Late Stages ◽  
Insight Into

After briefly reviewing our understanding of Miras and their evolutionary status, three aspects of real-time evolution in these and related stars are examined: 1.Chemical changes (O-rich to C-rich) due to third dredge-up,2.Period changes due to the effects of the helium shell-flash,3.The existence of ‘fossil’ dust and gas shells. Studies of resolved gas and dust shells are highlighted as particularly interesting. They will enable us to examine the mass-loss histories of many late-type stars over the last ten thousand years or so. Such observations have only recently become technically feasible and they are expected to provide important new insight into the late stages of stellar evolution.

scholarly journals Specification and Verification in Integrated Model of Distributed Systems (IMDS)

Computers ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 65 ◽  
Author(s):  
Wiktor Daszczuk
Keyword(s):  
Distributed Systems ◽  
Rapid Development ◽  
Integrated Model ◽  
Automated Verification ◽  
Independent Components ◽  
Uniform Model ◽  
Relationship Of ◽  
The Relationship ◽  
Natural Characteristics ◽  
The Internet Of Things

Distributed systems, such as the Internet of Things (IoT) and cloud computing, are becoming popular. This requires modeling that reflects the natural characteristics of such systems: the locality of independent components, the autonomy of their decisions, and asynchronous communication. Automated verification of deadlocks and distributed termination supports rapid development. Existing techniques do not reflect some features of distribution. Most formalisms are synchronous and/or use some kind of global state, both of which are unrealistic. No model supports the communication duality that allows the integration of a remote procedure call and client-server paradigm into a single, uniform model. The majority of model checkers refer to total deadlocks. Usually, they do not distinguish between communication deadlocks from resource deadlocks and deadlocks from distributed termination. Some verification mechanisms check partial deadlocks at the expense of restricting the structure of the system being verified. The paper presents an original formalism for the modeling and verification of distributed systems. The Integrated Model of Distributed Systems (IMDS) defines a distributed system as two sets: states and messages, and the relationship of the “actions” between these sets. Communication duality provides projections on servers and on traveling agents, but the uniform specification of the verified system is preserved. General temporal formulas over IMDS, independent of the structure of the verified system, allow automated verification. These formulas distinguish between deadlocks and distributed termination, and between communication deadlocks and resource deadlocks. Partial deadlocks and partial termination can be checked. The Dedan tool was developed using IMDS formalism.

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