Adam Moroz

Sliding Wear Characteristics and Corrosion Behaviour of Selective Laser Melted 316L Stainless Steel

Stainless steel is one of the most popular materials used for selective laser melting (SLM) processing to produce nearly fully dense components from 3D CAD models. The tribological and corrosion properties of stainless steel components are important in many engineering applications. In this work, the wear behaviour of SLM 316L stainless steel was investigated under dry sliding conditions, and the corrosion properties were measured electrochemically in a chloride containing solution. The results show that as compared to the standard bulk 316L steel, the SLM 316L steel exhibits deteriorated dry sliding wear resistance. The wear rate of SLM steel is dependent on the vol.% porosity in the steel and by obtaining full density it is possible achieve wear resistance similar to that of the standard bulk 316L steel. In the tested chloride containing solution, the general corrosion behaviour of the SLM steel is similar to that of the standard bulk 316L steel, but the SLM steel suffers from a reduced breakdown potential and is more susceptible to pitting corrosion. Efforts have been made to correlate the obtained results with porosity in the SLM steel.

Cooperative and collective effects in light of the maximum energy dissipation principle

The collective phenomena in physics and cooperative phenomena in biology/chemistry is compared in terms of the variational description. The maximum energy dissipation principle is employed and the cost-like functional is chosen according to an optimal control based formulation (Moroz, 2008; Moroz, 2009). Using this approach, the variational outline has been considered for non-equilibrium thermodynamic conditions. The differences between the application of the proposed approach to the description of cooperative phenomena in chemical/biochemical kinetics and the Landau free energy approach to collective phenomena in physics have been investigated.

Realising a child's imagination through a child-led product design for both two-dimensional and three-dimensional products

The imagination and creative ability of a child is something that is a pleasure to see in designs created by children. Unfortunately, when children design, they are subject to adult influence, which is reflected in designs that show lower creativity. In order to realise the purity of the imagination of the child, adult involvement needs to be excluded. This study is based on the argument that children can produce pure art if pedagogical influences are excluded. Children created designs independent of adult involvement during the study and the creativity in their work was measured against factors in terms of pure and uninfluenced design. Comparisons were made with designs produced in school. The child-led approach was extended to realise designs through 2D and 3D product development, using silk-screen and 3D printing. The results showed that an absence of adult involvement increased creativity.

Some General Optimal Control Problems Useful for Biokinetics

The chapter begins with a discussion of the basic linear examples in a comparison between mechanics and thermodynamic/biological kinetics from the perspective of the maximum energy dissipation (MED) principle, the least action principle, and optimal control. In the second part, the formulation of optimal control and variational methods are applied to a general one-dimensional case. Furthermore, examples are discussed such as a one-dimensional case with the control by the velocity of process (“additive” control) and with the control by the rate constant of the velocity (“multiplicative” control). General case of multiplicative control model, the logistic model, and the Michaelis–Menten/Monod model have been interpreted in terms of optimal control. The introduction of control into the logistic model is considered. In the third part, the “additive” and “multiplicative” optimal control schemes are considered in a multidimensional case. The link to linear-quadratic regulator and matrix Riccati equations is discussed in the case of additive control. In the “multiplicative” control model, the equations are derived in a vector form. Some particular examples are illustrated. The link to the MED principle is discussed.

Phenomenological Cost and Penalty Interpretation of the Lagrange Formalism in Physics

Publisher Summary Current considerations in physical formalism concerns only classical and fundamental ideas, based on the Lagrange approach. This is predetermined by the phenomenological character of the considered phenomena and also by an attempt to find a relation to the biological, explicit penalty perspective. It is obviously possible, and this point of view could thus be transformed into a system of views, to some extent relevant to the standard one. It is important in a general sense that the common biological and physical systems have views that are based on the combination of the maximum energy dissipation/least action principle. Thus, the consideration used in mechanics or the classical field theory of the forms of the Lagrange function or Lagrangian includes a local, instantaneous physical penalty, their internal, specific properties of physical symmetry and its breaking, and a penalty interpretation of physical evolution. A fairly acceptable and not contradictory interpretation in relation to the maximum energy dissipation principle is discussed for biology. Thus, the form of the penalty with alternating sign can be interpreted as internal payment or interpayment of the penalty by internal degrees of freedom, while the form of the penalty with only positively determined parts is more characteristic for biology. The consideration of physical formalism presents as one of its main questions the relationships between physics and biology—and to what extent there is a flow of instability supporting the existence of the physical world, considering the formal expression by positively determined components of the generalized penalty

Conceptual Aspects of the Common Extrema in Biology and Physics

On the basis of the maximum energy dissipation/least action principle, a methodological unification of natural (physical) and biological regularities is formally discussed. A general consideration results in the ideological penetration of biology into physics. An important conclusion follows through the penalty interpretation of the least action principle: instability and its intensive penalty evaluation—energy, specifically free energy, which strives toward equilibrium and to stability in an extreme way according to the maximum energy dissipation principle. Few models of evolution are discussed.

Extreme Character of Evolution in Trophic Pyramid of Biological Systems and the Maximum Energy Dissipation/Least Action Principle

In this section, we outline a framework that shows that biological evolution can be considered from the perspective of the maximum energy dissipation principle. From this perspective, the emergence of biological systems and their evolution can be treated as a further acceleration of the global free energy dissipation rate. There are key stages in the consequent emergence of essentially new levels of evolution (biological cell, multicellular organism, social system) that are suggested as the result of cooperation/symbiosis of the biological systems at the previous levels. The cooperation indeed provides enough complexity for development of an essentially new and higher level of dissipation: new form of metabolism, adaptation, and information mapping for organization and control of the upper level system. Every significant new step of biological evolution can be considered as a phase transition to the next level of the acceleration of global free energy dissipation. Thermodynamically speaking, every qualitatively new level of biological organization provides essentially a qualitatively higher rate of free energy dissipation from the new energy-and-material sources, essentially widening the number of these sources. In the sense of maximum energy dissipation/least action principle, the emergence and existence of biological systems is the direct requirement of this principle, which makes the existence of the biological world in agreement with physics as whole.

Extreme Energy Dissipation

In this chapter, thermodynamics as a science that connects physics and biology by the phenomenology of energetic transformations is considered. However, thermodynamics is the simplest model of physical systems, with only two levels of hierarchy: the macroscopic and microscopic. The macroscopic nature of basic thermodynamic quantities—energy, heat and work, free energy, and thermodynamic entropy—is discussed together with the main properties of free energy dissipation or entropy production. The biological multileveled hierarchy and thermodynamic two-leveled hierarchy are compared. A growing role of phenomenological outline in the unified description of the multiple/complex hierarchy of biological systems is suggested. The role of extreme principles in physical description is illustrated in the second section. Two opposite concepts—the Prigogine principle of the minimum entropy production and the Ziegler principle of the maximum rate of energy dissipation—are discussed. The relation of the Ziegler principle to the least action principle has been suggested. The dimensionality idea is used to interpret the least action principle of thermodynamics. In the third section, the dynamic optimal control formulation of mechanics is illustrated. Using this example, the dynamic optimal control approach to formulate the variational framework for nonequilibrium thermodynamics has been proposed. Traditional Lagrange and Hamilton formulations of the variational problem for nonequilibrium thermodynamics are illustrated, as is the Hamilton–Jacobi equation. Within this optimal control-based variational approach, the role of free energy in the cost (penalty) function is discussed, as well as the energetical cost/penalty interpretation of the Lagrangian and Hamiltonian functions and the thermodynamic momenta. Relaxation in an RC circuit in terms of proposed approach is illustrated as simple physical example.

The population model of bone remodelling employed the optimal control

Several models have been developed in recent years which apply population dynamics methods to describe the mechanisms of bone remodelling. This study incorporates the population kinetics model of bone turnover (including the osteocyte loop regulation) with the optimal control technique. Model simulations have been performed with a wide range of rate parameters using the Monte Carlo method. The regression method has also been used to investigate the interdependence of the location of equilibrium and the characteristics of the equilibrium/relaxation time on the rate parameters employed. The dynamic optimal control outlook for the regulation of bone remodelling processes, in the context of the osteocyte-control population model, has been discussed. Optimisation criteria have been formulated from the perspective of the energetic and metabolic losses in the tissue, with respect to the performance of the bone multicellular unit.

Bone Turnover Cycle Model with a Torus-Like Steady State

A quantitative understanding of the bone remodeling process is of considerable biomedical and practical biotechnological interest to support the application of layer manufacturing techniques to produce scaffolds for surgical applications. Osteoclasts and osteoblasts play a principal role in different models of the bone multicellular unit operating in bone and display a rich spectrum of behaviour. The goal of this work is to show that it is possible to capture the cyclic dynamics of operating cells. The central idea of the mathematical model is that the regulatory nature of osteocytes is the basis of the cyclic-like behaviour associated with the system (remodeling process)as a whole. We developed this model taking due account of the apoptosis of osteocytes as a possible regulation loop in bone remodeling control. By applying the ordinary differential equations technique to the model, we show cyclic modes over a wide range of constants that have clear biological relevance. Simulations show that for a particular range of constants the model exhibits a torus-like quasi-steady state. Further investigation into these simulations indicates the existence of a surface in the osteoclasts-osteoblasts-osteocytes-bone space, that could be interpreted as a conservative value confirming the substrate-energy regenerative capability of the bone remodeling system. It is suggested that the nature of this recovering potential is directed against both mechanical and biochemical damage to the bone.