Active impulsive disturbance rejection and oscillation control of robot manipulator, using nonclassical rod models and proportional integral derivative controller

Micro-electro-mechanical-systems scale robots are prone to impulsive disturbances during operation. Such disturbance leads to adverse oscillations of the robot manipulator. So, it is essential to mitigate and control such unwanted oscillations. On the other hand, to capture size dependencies of such robot elements, it is required to adopt nonclassical models. To address these cases, robot manipulator is modeled as a mechanical rod, comprehensive rod models are utilized, proportional integral derivative (PID) controller is designed, and the time-domain response of the system is simulated in MATLAB. Results show that adopting proper gain values of the PID controller leads to total rejection of the pulsive disturbances. However, findings conceal the importance of the nonclassical rod model such that strain gradient (SG) model shows less oscillatory amplitude than the classical theory (CT) model. While considering the nonlocal model effects (NL), such undesired vibrations are bigger than CT model. In other words, meanwhile, a simple PID controller can reject the disturbance for SG models; a stronger controller should be adopted to reject such pulsive disturbances with NL models. Eventually, it is valuable to note that to suppress unwanted oscillations in small-sized robots, PID closed-loop feedback controller is a decent choice because of the simplicity and less costs. Application of successful control design alongside the proper nonclassical theory leads to neutralizing the disturbances and increases the robot manipulator precision.

The Ambiguous Functions of the Precursors That Enable Nonclassical Modes of Olanzapine Nucleation and Growth

One of the most consequential assumptions of the classical theories of crystal nucleation and growth is the Szilard postulate, which states that molecules from a supersaturated phase join a nucleus or a growing crystal individually. In the last 20 years, observations in complex biological, geological, and engineered environments have brought to light violations of the Szilard rule, whereby molecules assemble into ordered or disordered precursors that then host and promote nucleation or contribute to fast crystal growth. Nonclassical crystallization has risen to a default mode presumed to operate in the majority of the inspected crystallizing systems. In some cases, the existence of precursors in the growth media is admitted as proof for their role in nucleation and growth. With the example of olanzapine, a marketed drug for schizophrenia and bipolar disorder, we demonstrate that molecular assemblies in the solution selectively participate in crystal nucleation and growth. In aqueous and organic solutions, olanzapine assembles into both mesoscopic solute-rich clusters and dimers. The clusters facilitate nucleation of crystals and crystal form transformations. During growth, however, the clusters land on the crystal surface and transform into defects, but do not support step growth. The dimers are present at low concentrations in the supersaturated solution, yet the crystals grow by the association of dimers, and not of the majority monomers. The observations with olanzapine emphasize that detailed studies of the crystal and solution structures and the dynamics of molecular association may empower classical and nonclassical models that advance the understanding of natural crystallization, and support the design and manufacture of promising functional materials.

POSSIBILITIES OF PSYCHOSEMANTIC APPROACH FOR THE ANALYSIS OF MODERN SPECIALISTS’ PROFESSIONAL ACTIVITY

Relevance. The article analyzes the problems of modern researchers studying the “man — work” system from the standpoint of post-nonclassical models that develop the idea of “subjectivity” in the relationship between man and world. It is necessary to develop a methodological approach for an adequate noncontroversial description of the world of professionals. Such an approach should describe this system in a consistent way, allow for correlation of ideas about it with the reality itself and remove the limitations associated with the researcher’s abilities. Objective. The purpose of the paper is to discuss the possibilities of psychosemantic approach for studying professional activity on the example of two pieces of empirical research on the activities of medical workers employed by commercial and budgetary organizations and having to do with different contingents of patients. Methods. In the studies conducted we used the survey methods “Integral Satisfaction with Work” (developed by V.A. Rozanova), “Professional Burnout” (N. E. Vodopyaynova, E.S. Starchenkova) and psychosemantic methods: semantic differential “My Work”; free associations; 10 unfinished sentences on the topic “My Work”; C. Osgood’s 14-scale semantic differential modified by E.Yu. Artemyeva. Sample. The study involved 212 doctors with different career span, of which 66 people are employees of budget hospitals, 36 people work in commercial medical centers, 60 people are maternity hospital employees, and 50 people work in a hospice. Results. Semantic features such as “emotional tone of assessment”, “ratio of semantic coincidence between descriptions of different “types” of work object (in our case,“Man” and “Patient”)” and “abstractness/concreteness of descriptions” reflect the conceptual characteristics of professional experience of doctors working in different organizations and with different contingents of patients. Conclusions. The psychosemantic approach to studying the “person — work” system, in which the activity approach of a person to the world is postulated, makes it possible to provide an adequate description of complex systems in a changing environment. The methods of psychosemantics, due to their “sensitivity” to shades of meaning of the words used by respondents, correspond to the idea of post-nonclassical models of mental determination, when external influences are mediated by the activity of a person and by the current structures of his or her subjective experience.

The Dental Lamina: An Essential Structure for Perpetual Tooth Regeneration in Sharks

Synopsis In recent years, nonclassical models have emerged as mainstays for studies of evolutionary, developmental, and regenerative biology. Genomic advances have promoted the use of alternative taxa for the study of developmental biology, and the shark is one such emerging model vertebrate. Our research utilizes the embryonic shark (Scyliorhinus canicula) to characterize key developmental and regenerative processes that have been overlooked or not possible to study with more classic developmental models. Tooth development is a major event in the construction of the vertebrate body plan, linked in part with the emergence of jaws. Early development of the teeth and morphogenesis is well known from the murine model, but the process of tooth redevelopment and regeneration is less well known. Here we explore the role of the dental lamina in the development of a highly regenerative dentition in sharks. The shark represents a polyphyodont vertebrate with continuously repeated whole tooth regeneration. This is presented as a major developmental shift from the more derived renewal process that the murine model offers, where incisors exhibit continuous renewal and growth of the same tooth. Not only does the shark offer a study system for whole unit dental regeneration, it also represents an important model for understanding the evolutionary context of vertebrate tooth regeneration.

Nonclassical dynamic modeling of nano/microparticles during nanomanipulation processes

Since the manipulation of particles using atomic force microscopy is not observable in real-time, modeling the manipulation process is of notable importance, enabling us to investigate the dynamical behavior of nanoparticles. To model this process, previous studies employed classical continuum mechanics and molecular dynamics simulations which had certain limitations; the former does not consider size effects at the nanoscale while the latter is time consuming and faces computational restrictions. To optimize accuracy and computational costs, a new nonclassical modeling of the nanomanipulation process based on the modified couple stress theory is proposed that includes the size effects. To this end, after simulating the critical times and forces that are required for the onset of nanoparticle motion on the substrate, along with the dominant motion mode, the nonclassical theory of continuum mechanics and a developed von Mises yield criterion are employed to investigate the dynamical behavior of a cylindrical gold nanoparticle during manipulation. Timoshenko and Euler–Bernoulli beam theories based on the modified couple stress theory are used to model the dynamics of cylindrical gold nanoparticles while the finite element method is utilized to solve the governing equations of motion. The results show a difference of 90% between the classical and nonclassical models in predicting the maximum deflection before the beginning of the dominant mode and a difference of more than 25% in the dynamic modeling of a 200 nm manipulation of a gold nanoparticle with a length of 25 µm and aspect ratio of 30. This difference increases with each increment of the aspect ratio and reduction of manipulation distance. Furthermore, by applying an extended von Mises criterion on the modified couple stress theory, it is found that the failure aspect ratio of a cylindrical gold nanoparticle based on nonclassical models is 212% more than that of the classical model. In the end, the results are compared with those of the classical method on polystyrene nanorods. The results for cylindrical gold nanoparticles indicate that the material length scale has a major effect on the exact positioning of cylindrical nanoparticles.