Skeptical Theism and the Creep Problem

Skeptical theism is the view that human knowledge and understanding are severely limited, compared to that of the divine. The view is deployed as an undercutting defeater for evidential arguments from evil. However, skeptical theism has broader skeptical consequences than those for the argument from evil. The epistemic principles of this skeptical creep are identified and shown to be on the road to global skepticism.

On the analytical solution of one creep problem

The analytical solution of one initial value problem for the system of two ordinary differential equations describing the fracture process of metal structures in deflected mode at creep conditions is considered in the paper. Similar problems arise when calculating the strength characteristics and estimating residual deformations in the design of nuclear reactors, in building and aerospace industries and in mechanical engineering. The solvability of the creep constitutive equations’ system is of great practical importance. The possibility of obtaining an exact analytical solution makes it possible to significantly simplify both the identification of creep characteristics and the process of model examination. Necessary and sufficient integrability conditions imposed on the parameters of the model are obtained for the initial problem using Chebyshev's theorem on the integration of a binomial differential. The recommendations for the numerical solution of the considered problem are given.

On the analytical solution of one creep problem

The analytical solution of one initial value problem for the system of two ordinary differential equations describing the fracture process of metal structures in deflected mode at creep conditions is considered in the paper. Similar problems arise when calculating the strength characteristics and estimating residual deformations in the design of nuclear reactors, in building and aerospace industries and in mechanical engineering. The solvability of the creep constitutive equations’ system is of great practical importance. The possibility of obtaining an exact analytical solution makes it possible to significantly simplify both the identification of creep characteristics and the process of model examination. Necessary and sufficient integrability conditions imposed on the parameters of the model are obtained for the initial problem using Chebyshev's theorem on the integration of a binomial differential. The recommendations for the numerical solution of the considered problem are given.

Calculation of Temperature Stresses in Polymers in the Cycles Heating-Cooling Process

In the constructions of multilayer cylindrical shells in heat-and-power engineering the materials, exhibiting rheological properties, such as concrete, polymers or fiber glass are widely used. In this connection, the study of temperature stresses in polymers, the analysis of the influence of various factors on the processes course under consideration, is of great importance. The paper presents an analytical solution of the thermal creep problem in polymers using the Kelvin-Voigt model for a rigidly clamped rod for various cases of temperature loading. The analysis of these solutions is also made on the example of a specific material for certain laws with changing temperature loads.

Modeling Creep Fracture in Rock by Using Kelvin Discretized Virtual Internal Bond

Discretized virtual internal bond (DVIB) is a lattice model, which is composed of bond cells. Each bond cell has a finite number of bonds. The DVIB is used to model the creep fracture. It is done by introducing a viscous bond to the original hyperelastic DVIB. The hyperelastic bond is parallel coupled with a viscous bond together, forming a hybrid hyperelastic-Kelvin bond. The hyperelastic bond reflects the microfracture mechanism, whereas the viscous bond reflects the creep mechanism. Based on this hyperelastic-Kelvin bond, the constitutive relation of a cell is derived. The microbond parameters are calibrated based on the ideal cell approach. The simulation results suggest that this method can represent the typical features of creep and can simulate the creep fracture. The merit of this method lies in that the complicated 3D macrocreep problem is reduced to the 1D microbond creep problem. No creep law is previously derived. The macrocreep fracture behavior is the natural response of the assembly of the micro hyperelastic-Kelvin bonds.

Stability Assurance in IT-Projects Management Systems

The paper is devoted to the IT-projects dynamics analysis in order to develop management processes that assure stability of the projects to scope changes. Software development lifecycle is considered combined with one of organizational changes which are carried out by IT-projects execution. This integral study of IT-projects organizational structure allows to discover projects particularities that lead to destabilization and especially "scope creep" as a main factor of loss of stability and, as a result, failure of objectives realization. To provide required level the model integrity IT-projects are to be considered in context of organization´s project portfolio as a part of business transformation program. The program in turn is studied not in its entire scope but particularly in its part relative to IT-project implementation together with obtaining desired results of its product utilization. To secure metrics-based project objectives achievement control an EVM modification for IT-projects management is presented in the article. Simulation that is also performed in the study illustrates internal causes of scope creep problem and its solution with methods developed in this study and thus project stability assurance.

The Effects of the Treatment of the Periodic Boundary Condition in TRIAINA Codes with a Pressure Tube Creep Problem

To verify the periodic boundary condition (PBC) treatment which was implemented in a TRI-angle elements induced numerical analyzer (TRIAINA), the pressure tube creep problem is chosen and examined with three cases of normal, 2.5% creep, and 5.0% creep on the aspects of the multiplication factor and relative pin power. The McCARD code is used for the homogenized group constants generation. It is shown that the differences are nearly negligible for the pressure tube creep problem.

HEREDITARY PROBLEMS IN LONG-WALL MINING BY FREE HEXAGONS

In deep mines, the way of excavation, depositing packs, and the mechanical properties as well as the velocity of mining belong to the most decisive phenomena for the threat of bumps. In this paper, time-dependent hereditary creep problem in terms of free hexagon distinct element method (DEM) is formulated and solved for assessment of bumps occurrence in deep mines. The time factor as an impact of the velocity of mining is involved here in a natural way in the model of discrete elements. Inside of these elements, the material behavior is described by the boundary element method. Mutual coupling of the velocity and the way of deposition of packs can principally influence the safety against bumps. For the correct understanding, the behavior of the rock aggregate (coal seam and the overburden) and the nucleation of cracks finally leading to the bumps have to be treated as time depended and creep and viscoplasticity in the overburden should be considered. In the coal seam, brittle material is adopted. According to the new experiments on scale models and results from accessible literature those effects will be involved into the formulations.

High Temperature Design of PVP Bolted Flanged Joints

This paper presents a summary of the principal findings of a recent ASME sponsored study into the analysis methods used for high temperature flanges. The intent of the project was to examine the requirements for high temperature flange design and provide guidance for inclusion of design methods into the modern ASME pressure vessel design codes. Throughout the project, it was kept in mind that high temperature flange joints are a relatively small portion of the flange population, and that improvements in Finite Element Analysis (FEA) and computing power are now to the point where very large non-linear creep problems can be solved relatively easily. Therefore, while the fundamentals of high temperature flange design using code equations were included in the assessment, the initial starting point for the project was to formulate guidelines for FEA of the creep problem, based on comparison with relatively scarce flange creep test data.