Modeling and proving dynamic behaviors of a routing protocol: A tutorial

With the increasing adoption of Internet of Things technologies for controlling physical processes, their dependability becomes important. One of the fundamental functionalities on which such technologies rely for transferring information between devices is packet routing. However, while the performance of Internet of Things–oriented routing protocols has been widely studied experimentally, little work has been done on provable guarantees on their correctness in various scenarios. To stimulate this type of work, in this article, we give a tutorial on how such guarantees can be derived formally. Our focus is the dynamic behavior of distance-vector route maintenance in an evolving network. As a running example of a routing protocol, we employ routing protocol for low-power and lossy networks, and as the underlying formalism, a variant of linear temporal logic. By building a dedicated model of the protocol, we illustrate common problems, such as keeping complexity in control, modeling processing and communication, abstracting algorithms comprising the protocol, and dealing with open issues and external dependencies. Using the model to derive various safety and liveness guarantees for the protocol and conditions under which they hold, we demonstrate in turn a few proof techniques and the iterative nature of protocol verification, which facilitates obtaining results that are realistic and relevant in practice.

Kansa Method for Unsteady Heat Flow in Nonhomogenous Material with a New Proposal of Finding the Good Value of RBF’s Shape Parameter

New engineering materials exhibit a complex internal structure that determines their properties. For thermal metamaterials, it is essential to shape their thermophysical parameters’ spatial variability to ensure unique properties of heat flux control. Modeling heterogeneous materials such as thermal metamaterials is a current research problem, and meshless methods are currently quite popular for simulation. The main problem when using new modeling methods is the selection of their optimal parameters. The Kansa method is currently a well-established method of solving problems described by partial differential equations. However, one unsolved problem associated with this method that hinders its popularization is choosing the optimal shape parameter value of the radial basis functions. The algorithm proposed by Fasshauer and Zhang is, as of today, one of the most popular and the best-established algorithms for finding a good shape parameter value for the Kansa method. However, it turns out that it is not suitable for all classes of computational problems, e.g., for modeling the 1D heat conduction in non-homogeneous materials, as in the present paper. The work proposes two new algorithms for finding a good shape parameter value, one based on the analysis of the condition number of the matrix obtained by performing specific operations on interpolation matrix and the other being a modification of the Fasshauer algorithm. According to the error measures used in work, the proposed algorithms for the considered class of problem provide shape parameter values that lead to better results than the classic Fasshauer algorithm.

Is the Prospective Link between Parental Stress and Adolescent Snack Intake or Weight Outcome Mediated by Food Parenting Practices?

Parental stress may influence adolescents’ food intake and weight development over time, however, it is largely unknown why this is the case. This study examines whether the link between parental stress and adolescents’ snack intake and weight outcome is mediated by food parenting practices (FPPs). Participants included 400 parents and their adolescent children (aged 12–16) who completed questionnaires. The Perceived Stress Scale (PSS) was used to assess parental general stress levels and the Adolescent Food Parenting Questionnaire (AFPQ) to assess FPPs. Multiple mediation analyses with parallel mediators were performed, with parental general stress as an independent variable and adolescent snack intake and zBMI as dependent variables. FPPs (autonomy support, coercive control, modeling, healthy structure, snack structure) were entered as mediators in the model, adjusted for covariates. Autonomy support mediated the link between parental general stress and adolescent savory snack and sweet snack intake at follow-up. Parents who reported higher stress levels provided less autonomy support, which resulted in more adolescent snacking. None of the other FPPs mediated any link between parental stress and intake or weight outcome, and no significant indirect effects were observed with zBMI as an outcome variable. Further research should replicate this finding and may further examine underlying mechanisms.

TRUST- BASED MODELING MAC-TYPE ACCESS CONTROL THROUGH ACCESS AND ACTIONS CONTROL POLICIES

In recent decades, the number of researches on access control and user actions in computer systems has increased. Over time, there have been two models of implementing Mandatory Access Control (MAC) policies for government institutions and Discretionary Access Control (DAC) for the business environment, policies that various access control modeling solutions seek to implement. Among the access control modeling solutions developed are Role-Based Access Control (RBAC) and Attribute-Based Access Control (ABAC), presented in the U.S.A. by the National Institute of Standard and Technology (NIST). In Romania, in 2010, the access control solution based on trust was presented. This paper presents Mandatory Access Control policy modeling using the trust-based access and actions control modeling solution.

3-DIMENTIONAL MODELING OF CYLINDRICAL CONCRETE UNDER AXIAL COMPRESSION WITH VARIATIONS OF MESH ELEMENT TECHNIC AND EFFECT OF REDUCED INTEGRATION

Research with numerical methods using computer programs has increased in recent years in various fields including the field of structural materials. However, this numerical analysis still needs to be developed in terms of modeling techniques in order to get the results according to the real condition. In this paper, modeling of concrete-cylinder with numerically method using a finite element based computer program, Abaqus®, presented.. Modeling technique to inventigate the mesh element technique and the reduced integration on hourglass control. Modeling specimen is in the form of cylindrical concrete measuring 150 mm x 300 mm with a quality of 25 MPa. Concrete plastic behavior is modeled with the concrete damage plasticity (CDP) feature. The results of the analysis show that the reduction-integration of hourglass control gives a lower peak load effect when the material passes the elastic limit. Meanwhile, a better mesh technique is to use 8-noded hexahedral because it is more stable and the reduction-integration effect of hourglass control can work.