From Geometry, Kinematics and Dynamics of Billiards to the Extended Theory of Skew Collision between Two Rolling Bodies and Methodology of Vibro-Impact Dynamics

Starting from explanation of geometry, kinematics and dynamics of game billiards, and phenomena of impact a rolling ball into different types of curved surfaces and direct and skew central collision of two rolling, same dimension, balls we open question of collision of two rolling axial symmetrically bodies with different dimensions and different forms. Use elementary approach and Petrovic's theory presented in two books “Elements of mathematical phenomenology” and “Phenomenological mappings”, extended theory of direct and skew central collision of two rolling, axially symmetric, but different dimensions and forms, bodies is formulated with all additional and new analytical expressions, theorems , to define all pre- and post- collision kinetic states. Use these new results complete methodology of vibro-impact system dynamics is formulated and applied for investigation kinetic parameters and phenomena in vibro-impact systems with successive collisions between two or a finite number of rolling bodies. Energy jumps in collisions between rolling bodies in vibroimpact system dynamics are indicated and analytically described in a number of these systems

Detection and analysis of new psittacine beak and feather disease virus (PBFDv) nucleotide sequences

ΔΕΝ ΥΠΑΡΧΕΙ ΠΕΡΙΛΗΨΗPsittacine beak and feather disease (PBFD) affects a large number of Psittaciformes species. In this study, five White Cockatoo parrots (Cacatua alba) with clinical signs of PBFD were examined. After euthanasia, a full necropsy of parrots was performed and organs with macroscopic changes were sampled for routine histopathological evaluation. To confirm the presence of psittacine beak and feather disease virus (PBFDv), feather samples were analyzed with the PCR method. Sequence analysis of the obtained PCR products indicated their close relationship (99%) to other PBFDv isolates. Six variable nucleotide sites were discovered, two missense and four silent mutations. This paper presents the evidence of new PBFDv sequence in Cockatoo species

A New Collision Model for Analysing the Vibro-Impact of Spur Gears

A model of a central centric collision of two fictive rolling disks, with radii equal to the radii of pitch diameters of coupled gears, is used to describe the vibro-impact dynamics of spur gears. Total deformations vary during the operation of spur gears with involute profile, particularly as a result of variable number of pairs of teeth in contact. These variations, as well as tooth profile misalignments or damages, lead to the backlash, the appearance of internal dynamic forces, and impact. Particular values of tooth profile parameters and transmission ratio create the conditions for a vibro-impact vibration regime. The vibro-impact gear dynamics is characterized by vibro-impact vibrations in the contact between the pinion tooth and the wheel tooth during a short period of time after the collision. New formulas for the calculation of the time periods between two tooth collisions, as well as between two successive tooth collision impacts, are devised. Also, a set of equations for the calculation of the disturbance angular velocity of the pinion called the transmission error is developed; the transmission error has a role of an excitation for vibro-impact vibrations in the gear tooth contact

Discrete fractional order system vibrations

A theory of free vibrations of discrete fractional order (FO) systems with a finite number of degrees of freedom (dof) is developed. A FO system with a finite number of dof is defined by means of three matrices: mass inertia, system rigidity and FO elements. By adopting a matrix formulation, a mathematical description of FO discrete system free vibrations is determined in the form of coupled fractional order differential equations (FODE). The corresponding solutions in analytical form, for the special case of the matrix of FO properties elements, are determined and expressed as a polynomial series along time. For the eigen characteristic numbers, the system eigen main coordinates and the independent eigen FO modes are determined. A generalized function of visoelastic creep FO dissipation of energy and generalized forces of system with no ideal visoelastic creep FO dissipation of energy for generalized coordinates are formulated. Extended Lagrange FODE of second kind, for FO system dynamics, are also introduced. Two examples of FO chain systems are analyzed and the corresponding eigen characteristic numbers determined. It is shown that the oscillatory phenomena of a FO mechanical chain have analogies to electrical FO circuits. A FO electrical resistor is introduced and its constitutive voltage–current is formulated. Also a function of thermal energy FO dissipation of a FO electrical relation is discussed

Promoting Client Participation and Constructing Decisions in Mental Health Rehabilitation Meetings

The chapter analyzes practices by which support workers promote client participation in mental health rehabilitation meetings at the Clubhouse. While promoting client participation, the support workers also need to ascertain that at least some decisions get constructed during the meetings. This combination of goals—promoting participation and constructing decisions—leads to a series of dilemmatic practices, the dynamics of which the chapter focuses on analyzing. The support workers may treat clients’ turns retrospectively as proposals, even if the status of these turns as such is ambiguous. In the face of a lack of recipient uptake, the support workers may remind the clients about their epistemic access to the content of the proposal or pursue their agreement or commitment to the idea. These practices involve the support workers carrying primary responsibility over the unfolding of interaction, which is argued to compromise the jointness of the decision-making outcome.The chapter analyzes practices by which support workers promote client participation in mental health rehabilitation meetings at the Clubhouse. While promoting client participation, the support workers also need to ascertain that at least some decisions get constructed during the meetings. This combination of goals—promoting participation and constructing decisions—leads to a series of dilemmatic practices, the dynamics of which the chapter focuses on analyzing. The support workers may treat clients’ turns retrospectively as proposals, even if the status of these turns as such is ambiguous. In the face of a lack of recipient uptake, the support workers may remind the clients about their epistemic access to the content of the proposal or pursue their agreement or commitment to the idea. These practices involve the support workers carrying primary responsibility over the unfolding of interaction, which is argued to compromise the jointness of the decision-making outcome.Peer reviewe

Accelerating Materials Development via Automation, Machine Learning, and High-Performance Computing

Successful materials innovations can transform society. However, materials research often involves long timelines and low success probabilities, dissuading investors who have expectations of shorter times from bench to business. A combination of emergent technologies could accelerate the pace of novel materials development by 10x or more, aligning the timelines of stakeholders (investors and researchers), markets, and the environment, while increasing return-on-investment. First, tool automation enables rapid experimental testing of candidate materials. Second, high-throughput computing (HPC) concentrates experimental bandwidth on promising compounds by predicting and inferring bulk, interface, and defect-related properties. Third, machine learning connects the former two, where experimental outputs automatically refine theory and help define next experiments. We describe state-of-the-art attempts to realize this vision and identify resource gaps. We posit that over the coming decade, this combination of tools will transform the way we perform materials research. There are considerable first-mover advantages at stake, especially for grand challenges in energy and related fields, including computing, healthcare, urbanization, water, food, and the environment.Comment: 22 pages, 3 figure