Numerical Simulation of Waves and Fronts in Inhomogeneous Solids

Dynamic response of inhomogeneous materials exhibits new effects, which often do not exist in homogeneous media. It is quite natural that most of studies of wave and front propagation in inhomogeneous materials are associated with numerical simulations. To develop a numerical algorithm and to perform the numerical simulations of moving fronts we need to formulate a kinetic law of progress relating the driving force and the velocity of the discontinuity. The velocity of discontinuity is determined by means of the non-equilibrium jump relations at the front. The obtained numerical method generalizes the wave-propagation algorithm to the case of moving discontinuities in thermoelastic solids

Full Field Computing for Elastic Pulse Dispersion in Inhomogeneous Bars

In the paper, the finite element method and the finite volume method are used in parallel for the simulation of a pulse propagation in periodically layered composites beyond the validity of homogenization methods. The direct numerical integration of a pulse propagation demonstrates dispersion effects and dynamic stress redistribution in physical space on example of a one-dimensional layered bar. Results of numerical simulations are compared with analytical solution constructed specifically for the considered problem. Analytical solution as well as numerical computations show the strong influence of the composition of constituents on the dispersion of a pulse in a heterogeneous bar and the equivalence of results obtained by two numerical methods

Design And Application Of A Drill Pipe Fatigue Test Facility

This paper reports on the design and application of a fatigue testing facility for drill pipes. A reversed bending load is applied using a rotating drill pipe in a four point static bend arrangement with the possibility of applying an additional static tension load. Drill pipes were tested with and without static tension at different cyclic bending stresses. The stress amplitudes ranged from 30 MPa to 230 MPa on the outside surface of the drill pipe. The test results show a consistent failure mode with a circumferential crack propagating in the groove of the first engaged thread of the pin, i.e. the male section of the joint. The fracture surface as well as ultrasonic monitoring of the sample during the testing suggest that the circumferential crack growth rate is fast, and final fracture occurs within a relatively small number of cycles as soon as a through wall crack has been formed. The S-N curve collected from a total of 18 samples shows a linear trend in the logarithm of the fatigue life versus stress amplitude

Aptamer-based radiopharmaceuticals for diagnostic imaging and targeted radiotherapy of epithelial tumors

In the continuous search for earlier diagnosis and improved therapeutic modalities against cancer, based on our constantly increasing knowledge of cancer biology, aptamers hold the promise to expand on current antibody success, but overcoming some of the problems faced with antibodies as therapeutic or delivery agents in cancer. However, as the first aptamer reached the market as an inhibitor against angiogenesis for the treatment of macular degeneration, aptamers have found only limited applications or interest in oncology, and even less as radiopharmaceuticals for diagnostic imaging and targeted radiotherapy of tumours. Yet, the chemistry for the labelling of aptamers and the options to alter their pharmacokinetic properties, to make them suitable for use as radiopharmaceuticals is now available and recent advances in their development can demonstrate that these molecules would make them ideal delivery vehicles for the development of targeted radiopharmaceuticals that could deliver their radiation load with accuracy to the tumour site, offering improved therapeutic properties and reduced side effects

ВИХОВНІ ТЕХНОЛОГІЇ ЯК ІННОВАЦІЙНА І ПРІОРИТЕТНА СКЛАДОВА ФОРМУВАННЯ ОСОБИСТОСТІ СУЧАСНОГО ЛІКАРЯ

The aim of the work – to determine the role of different educational technologies used by the stuff of the Department of Internal Medicine 1 of the State Institution “Dnipropetrovsk Medical Academy of the Ministry of Health of Ukraine” (SI “DMA”).The main body. Modern education in Ukraine should ensure the adherence of young people to world and national culture, to universal values. According to the forms and methods, it can be implemented in different directions – from training of future doctors for cooperation within the framework of schools for patients with different chronic pathologies. The staff of the department pays great attention to the comprehensive education of the future generation of doctors and teachers, knowing well that it should be not only knowledgeable but emotionally sound and well-informed. For this purpose, young people are attracted to visits to theaters, museums of the city, exhibitions of works of folk art craftsmen, etc.Conclusions. Different educational technologies form the high-quality qualities of a modern physician. The experience of Dnipropetrovsk Medical Academy has a powerful arsenal of pedagogical innovations in the educational process. The effectiveness of their implementation depends on the traditions of the educational institution, as well as the abilities, skills and desires of the teaching staff.Мета роботи – визначити роль різних виховних технологій, які використовують співробітники кафедри внутрішньої медицини 1 Державного закладу “Дніпропетровська медична академія Міністерства охорони здоров’я України” (ДЗ “ДМА”), у формуванні особистості сучасного лікаря.Основна частина. Сучасне виховання в Україні повинне забезпечувати долучення молоді до світової й національної культури, до загальнолюдських цінностей. За формами й методами воно може впроваджуватися у   різних напрямках – від навчання майбутніх лікарів щодо співпраці у рамках шкіл для хворих з різною хронічною патологією. Співробітники кафедри приділяють велику увагу всебічному вихованню майбутнього покоління лікарів і викладачів, добре розуміючи, що воно повинно бути не лише багато у чому обізнаним, а й емоційно здоровим та виваженим. Задля цієї мети молодь залучається до відвідувань театрів, музеїв міста, виставок робіт майстрів народної творчості тощо.Висновки. Різні виховні технології формують високоморальні якості сучасного лікаря. Досвід ДЗ “ДМА” має потужний арсенал застосування педагогічних інновацій у навчально-виховному процесі. Ефективність їх впровадження залежить від традицій навчального закладу, а також здібностей, вмінь і бажань педагогічного колективу

Derivation of dual horizon state-based peridynamics formulation based on euler-lagrange equation

The numerical solution of peridynamics equations is usually done by using uniform spatial discretisation. Although implementation of uniform discretisation is straightforward, it can increase computational time significantly for certain problems. Instead, non-uniform discretisation can be utilised and different discretisation sizes can be used at different parts of the solution domain. Moreover, the peridynamic length scale parameter, horizon, can also vary throughout the solution domain. Such a scenario requires extra attention since conservation laws must be satisfied. To deal with these issues, dual-horizon peridynamics was introduced so that both non-uniform discretisation and variable horizon sizes can be utilised. In this study, dual-horizon peridynamics formulation is derived by using Euler–Lagrange equation for state-based peridynamics. Moreover, application of boundary conditions and determination of surface correction factors are also explained. Finally, the current formulation is verified by considering two benchmark problems including plate under tension and vibration of a plate

Variational Foundations and Generalized Unified Theory of RVE-Based Multiscale Models

A unified variational theory is proposed for a general class of multiscale models based on the concept of Representative Volume Element. The entire theory lies on three fundamental principles: (1) kinematical admissibility, whereby the macro- and micro-scale kinematics are defined and linked in a physically meaningful way; (2) duality, through which the natures of the force- and stress-like quantities are uniquely identified as the duals (power-conjugates) of the adopted kinematical variables; and (3) the Principle of Multiscale Virtual Power, a generalization of the well-known Hill-Mandel Principle of Macrohomogeneity, from which equilibrium equations and homogenization relations for the force- and stress-like quantities are unequivocally obtained by straightforward variational arguments. The proposed theory provides a clear, logically-structured framework within which existing formulations can be rationally justified and new, more general multiscale models can be rigorously derived in well-defined steps. Its generality allows the treatment of problems involving phenomena as diverse as dynamics, higher order strain effects, material failure with kinematical discontinuities, fluid mechanics and coupled multi-physics. This is illustrated in a number of examples where a range of models is systematically derived by following the same steps. Due to the variational basis of the theory, the format in which derived models are presented is naturally well suited for discretization by finite element-based or related methods of numerical approximation. Numerical examples illustrate the use of resulting models, including a non-conventional failure-oriented model with discontinuous kinematics, in practical computations