Integrability versus topology of configuration manifolds and domains of possible motions

We establish a generic sufficient condition for a compact $n$-dimensional manifold bearing an integrable geodesic flow to be the $n$-torus. As a complementary result, we show that in the case of domains of possible motions with boundary, the first Betti number of the domain of possible motions may be arbitrarily large

A model for separatrix splitting near multiple resonances

We propose a model for local dynamics of a perturbed convex real-analytic Liouville-integrable Hamiltonian system near a resonance of multiplicity $1+m, m\geq 0$. Physically, the model represents a toroidal pendulum, coupled with a Liouville-integrable system of $n$ non-linear rotators via a small analytic potential. The global bifurcation problem is set-up for the $n$-dimensional isotropic manifold, corresponding to a specific homoclinic orbit of the toroidal pendulum. The splitting of this manifold can be described by a scalar function on an $n$-torus, whose $k$th Fourier coefficient satisfies the estimate $$O(e^{- \rho|k\cdot\omega| - |k|\sigma}), k\in\Z^n\setminus\{0\},$$ where $\omega\in\R^n$ is a Diophantine rotation vector of the system of rotators; $\rho\in(0,{\pi\over2})$ and $\sigma>0$ are the analyticity parameters built into the model. The estimate, under suitable assumptions would generalize to a general multiple resonance normal form of a convex analytic Liouville integrable Hamiltonian system, perturbed by O(\eps), in which case \omega_j\sim\omeps, j=1,...,n.Comment: 24 page

Alternative Measures of Total Factor Productivity Growth

The four main approaches to the measurement of total factor productivity (TFP)-growth and its decomposition are (i) Solow's residual analysis, (ii) the Index Number Approach, (iii) Input-Output Analysis (IO), and (iv) Data Envelopment Analysis (DEA).The corresponding measures of TFP growth are based on different assumptions, which we expose and interrelate.The Solow Residual serves as the benchmark for our comparisons.The interrelationships between the alternative measures permit an interpretation of the differences among them.We consolidate the four alternative measures in a common framework.TFP;Solow residual;Index numbers;Input-output;DEA

Atomic Force Microscopy and Real Atomic Resolution. Simple Computer Simulations.

Using a simple computer simulation for AFM imaging in the contact mode, pictures with true and false atomic resolution are demonstrated. The surface probed consists of two f.c.c. (111) planes and an atomic vacancy is introduced in the upper layer. Changing the size of the effective tip and its registry with respect to the atoms of the crystal probed, images with completely different qualitative features are obtained. If the effective tip is a single atom the vacancy is clearly imaged. However, if the tip consists of several atoms and is in registry with the sample, a virtual atom appears instead of the vacancy and the crystal lattice is perfectly reproduced. If the tip is out of registry with respect to the sample, artifacts having the size of the effective tip are reported.

Crystal and magnetic structure of substituted lanthanum cobaltites

The crystal and magnetic structures of the lanthanum cobaltites La0.6Sr0.4CoO3, La0.6Sr0.4Co0.9Fe0.1O3 and La0.6Ba0.4Co0.9Fe0.1O3 have been studied by neutron powder diffraction at temperatures of 2, 300 and 900 K. All compounds undergo a phase transition from cubic to rhombohedral structure. Below the room temperature La0.6Sr0.4CoO3 becomes ferromagnetic while for the components with 10% Fe substituted for Co, we found an antiferromagnetic order

Impact Assessment of Hypothesized Cyberattacks on Interconnected Bulk Power Systems

The first-ever Ukraine cyberattack on power grid has proven its devastation by hacking into their critical cyber assets. With administrative privileges accessing substation networks/local control centers, one intelligent way of coordinated cyberattacks is to execute a series of disruptive switching executions on multiple substations using compromised supervisory control and data acquisition (SCADA) systems. These actions can cause significant impacts to an interconnected power grid. Unlike the previous power blackouts, such high-impact initiating events can aggravate operating conditions, initiating instability that may lead to system-wide cascading failure. A systemic evaluation of "nightmare" scenarios is highly desirable for asset owners to manage and prioritize the maintenance and investment in protecting their cyberinfrastructure. This survey paper is a conceptual expansion of real-time monitoring, anomaly detection, impact analyses, and mitigation (RAIM) framework that emphasizes on the resulting impacts, both on steady-state and dynamic aspects of power system stability. Hypothetically, we associate the combinatorial analyses of steady state on substations/components outages and dynamics of the sequential switching orders as part of the permutation. The expanded framework includes (1) critical/noncritical combination verification, (2) cascade confirmation, and (3) combination re-evaluation. This paper ends with a discussion of the open issues for metrics and future design pertaining the impact quantification of cyber-related contingencies

Research of interconnected wind turbines with intelligent control

Development of renewable energy sources in Kazakhstan, including wind energy, brings the needs to design and develop control and integration to a power system. The aim of the Project is to design a power converter supplied by intelligent controllers that provide a stable 3-phase output voltage in the presence of uncertain fluctuations of a wind speed

Research of interconnected wind turbines with intelligent control

Development of renewable energy sources in Kazakhstan, including wind energy, brings the needs to design and develop control and integration to a power system. The aim of the Project is to design a power converter supplied by intelligent controllers that provide a stable 3-phase output voltage in the presence of uncertain fluctuations of a wind speed