Inherent Stability of Multibody Systems with Variable-Stiffness Springs via Absolute Stability Theory

In this paper, the inherent stability problem for multibody systems with variable-stiffness springs (VSSs) is studied. Since multibody systems with VSSs may consume energy during the variation of stiffness, the inherent stability is not always ensured. The motivation of this paper is to present sufficient conditions that ensure the inherent stability of multibody systems with VSSs. The absolute stability theory is adopted, and N-degree-of-freedom (DOF) systems with VSSs are formulated as a Lur’e form. Furthermore, based on the circle criterion, sufficient conditions for the inherent stability of the systems are obtained. In order to verify these conditions, both frequency-domain and time-domain numerical simulations are conducted for several typical low-DOF systems.

Graphical criteria of inherent stability of river vessels for the case of shallow waters navigation

Форма корпуса речного водоизмещающего судна во многом определяет его динамические свойства. Удачно подобранные геометрические параметры обеспечивают судну не только требуемую грузоподъемность и грузовместимость, но и предсказуемую управляемость при различных внешних условиях. Задача проектирования корпусов судов с заданными характеристиками управляемости связана с исследованием связи между геометрией корпуса и его динамикой. Динамику судна оценивают по виду характеристики управляемости и по критериям переходных процессов при выполнении специальных маневров головными судами серии или масштабными моделями [1, 2]. Использование таких методов затруднительно на этапе проектирования, так как необходимо изготовить масштабную модель и провести ее испытания при различных внешних условиях. Кроме того, этот способ достаточно затратный по времени, особенно если требуется изготавливать большое количество моделей. С целью сокращения числа моделей предлагается на этапе проектирования качественно оценивать динамические свойства будущего корпуса, а на этапе натурных экспериментов производить только небольшие корректировки. The hull geometry of a displacement riverboat largely determines its dynamic properties. Successfully selected geometric parameters provide a vessel not only with required cargo capacity and carrying capacity, but also with predictable steerability under various external conditions. The task of ship hull design with preset steerability properties is connected with investigation of relation between geometry of the hull and its dynamics. Vessel dynamics is estimated by type of controllability characteristic and by criteria of transients during special maneuvers by head vessels of series or scale models [1, 2]. The use of such methods is difficult at the design stage, since it is necessary to make a scale model and test it under various external conditions. In addition, this method is quite time-consuming, especially if a large number of models is required. In order to reduce the number of models, it is proposed to assess qualitatively the dynamic properties of the future hull at the design stage, and to make only small adjustments at the stage of full-scale experiments.

Assembly of discrete and oligomeric structures of organotin double-decker silsesquioxanes: inherent stability studies

Discrete and oligomeric organotin DDSQs have been synthesized and characterized, both experimentally and through computational study. The stability of these compounds remains intrigued with the organization of their structure in the crystal lattice.

Spontaneous skyrmionic lattice from anisotropic symmetric exchange in a Ni-halide monolayer

Topological spin structures, such as magnetic skyrmions, hold great promises for data storage applications, thanks to their inherent stability. In most cases, skyrmions are stabilized by magnetic fields in non-centrosymmetric systems displaying the chiral Dzyaloshinskii-Moriya exchange interaction, while spontaneous skyrmion lattices have been reported in centrosymmetric itinerant magnets with long-range interactions. Here, a spontaneous anti-biskyrmion lattice with unique topology and chirality is predicted in the monolayer of a semiconducting and centrosymmetric metal halide, NiI2. Our first-principles and Monte Carlo simulations reveal that the anisotropies of the short-range symmetric exchange, when combined with magnetic frustration, can lead to an emergent chiral interaction that is responsible for the predicted topological spin structures. The proposed mechanism finds a prototypical manifestation in two-dimensional magnets, thus broadening the class of materials that can host spontaneous skyrmionic states.

Replacing FPTP

Canada’s use of the First-Past-the-Post electoral system has been defended due to its simplicity, constituency representation, and inherent stability. Arguments have been raised, however, that the system does not sufficiently represent Canadian demographics in parliament, it renders opposition parties ineffective, smaller parties have trouble or are unable to win seats in parliament, and regionally-concentrated parties are encouraged over national based ones. It has been suggested that adding an element of proportionality would address some of these issues. This paper seeks to consider this claim by examining the political outcomes of proportional electoral systems. The literature review outlined that the use of proportional systems increased descriptive as well as geographic representation, and was positively linked to voter turnout.

Boron Fullerenes (B40)—A Projecting Applicant for Molecular Devices: A Review

The field of molecular electronics has gained a great impetus in the recent times and made the fabrication of extremely small devices possible that demonstrates extraordinary electrical properties. Being superconductive, fullerenes have drawn concerted attention of the research community committed to the exploration of applications in the field of molecular electronics. After extensive research in the field of carbon fullerenes in the last decade, Boron based fullerenes have stolen the limelight for their inherent stability among fullerene group. While the properties of B80 fullerene are still under exploration, researchers have been successful in synthesizing all boron fullerenes B40 in the laboratory. B40 is distinctive from other known clusters of boron as it has extraordinary properties like high stability and comprises of both acidic and basic sites, making it an optimum choice for detecting a number of gases like hydrogen, ammonia and carbon dioxide. This paper gives a brief review about the properties of B40 and the comparative research done on Boron fullerene so far.