Effect of Noise on the Standard Mapping

The effect of a small amount of noise on the standard mapping is considered. Whenever the standard mapping possesses accelerator modes (where the action increases approximately linearly with time), the diffusion coefficient contains a term proportional to the reciprocal of the variance of the noise term. At large values of the stochasticity parameter, the accelerator modes exhibit a universal behavior. As a result the dependence of the diffusion coefficient on the stochasticity parameter also shows some universal behavior.Comment: Plain TeX, 18 pages, 4 figure

Impact of Conversion to Compact Fluorescent Lighting, and other Energy Efficient Devices, on Greenhouse Gas Emissions

Selecting appropriate boundaries for energy systems can be as challenging as it is important. In the case of household lighting systems, where does one draw these boundaries? Spatial boundaries for lighting should not be limited to the system that consumes the energy, but also consider the environment into which the energy flows and is used. Temporal boundaries must assess the energy system throughout its life cycle. These boundary choices can dramatically influence the analysis upon which energy strategies and policies are founded.This study applies these considerations to the “hot” topic of whether to ban incandescent light bulbs. Unlike existing light bulb studies, the system boundaries are expanded to include the effects incandescent light bulbs have on supplementing household space heating. Moreover, a life cycle energy analysis is performed to compare impacts of energy consumption and greenhouse gas emissions for both incandescent light bulbs and compact fluorescent light bulbs. This study focuses on Canada, which not only has ve large seasonal variations in temperature but which has announced a ban on incandescent light bulbs. After presenting a short history and description of incandescent light bulbs (ILBs) and compact fluorescent light bulbs (CFLBs), the notion that a ban on ILBs could alter (or even increase) greenhouse gas (GHG) emissions in certain regions of Canada are introduced. The study then applies a life cycle framework to the comparison of GHG emissions for the ILB and CFLB alternatives. Total GHG emissions for both alternatives are calculated and compared for the provinces of Canada and again a physical rebound effect sometimes occurs. Finally, the policy and decision making implications of the results are considered for each of these locations

Differential Form of the Collision Integral for a Relativistic Plasma

The differential formulation of the Landau-Fokker-Planck collision integral is developed for the case of relativistic electromagnetic interactions.Comment: Plain TeX, 5 page

In-line check valves for water hammer control

This study systematically explores the relatively neglected surge protection strategy of installing an in-line check valve at an intermediate point within a pipeline. The in-line check valve is selected to isolate part of the system from a high-pressure source of fluid subsequent to a low-pressure water hammer event, in this way greatly reducing or eliminating any return surge. A typical application involving a pipeline with an isolated high point within its profile is numerically investigated. The low pressure transient event first opens an air-vacuum valve at the line’s high point. However, the violent expulsion and collapse of this air cavity is thereafter avoided, and thus the resulting water hammer pressures dramatically reduced, by an in-line check valve installed between the high point and the downstream reservoir. The effectiveness of the surge protection is shown to depend on hydraulics and topology of the line (particularly the position of the high point), on the position of the check valve, and on both the hydraulic and mechanical properties of the check valve. Although the check valve only protects the lower (normally upstream) portion of the line from the return surge, the transient response of the remainder of the line can sometimes be improved through installing either a bypass around the check valve or by perforating the check valve’s working element. The role and function of any pressure-relieving function at the valve is also numerically investigated and is shown to be a compromise between upstream and downstream protection.Bryan W. Karney and Angus R. Simpso

HISTORICAL REFLECTION ON THE USE OF BOLTZMANN APPROACHES FOR FLUID SYSTEM MODELING

ABSTRACT Ludwig Boltzmann, in the last quarter of the 19 th century, discovered how irreversible macroscopic laws could originate from the time-reversible microscopic laws of physics. Although the logic of Boltzmann analysis is indisputable, macroscopic-based methods have traditionally been the prime approaches for solving almost all fluid-related engineering problems, and only recently have the family of Boltzmann techniques become serious contenders for such applications. Using a backdrop of traditional CFD modeling, this paper highlights and summarizes the Boltzmann-based solution techniques

Negative pressures in full-scale distribution system: field investigation, modelling, estimation of intrusion volumes and risk for public health

International audienceVarious investigations encompassing microbial characterization of external sources of contamination (soil and trenchwater surrounding water mains, flooded air-valve vaults), field pressure monitoring, and hydraulic and transient analyses were conducted in the same distribution system where two epidemiological studies showing an increase in gastrointestinal illness for people drinking tap water were conducted in the 1990's. Interesting results include the detection of microorganisms indicators of fecal contamination in all external sources investigated but at a higher frequency in the water from flooded air-valve vaults, and the recording of 18 negative pressure events in the distribution system during a 17-month monitoring period. Transient analysis of this large and complex distribution system was challenging and highlighted the need to consider field pressure data in the process

Universal diffusion near the golden chaos border

We study local diffusion rate $D$ in Chirikov standard map near the critical golden curve. Numerical simulations confirm the predicted exponent $\alpha=5$ for the power law decay of $D$ as approaching the golden curve via principal resonances with period $q_n$ ($D \sim 1/q^{\alpha}_n$). The universal self-similar structure of diffusion between principal resonances is demonstrated and it is shown that resonances of other type play also an important role.Comment: 4 pages Latex, revtex, 3 uuencoded postscript figure

Asymptotic Statistics of Poincar\'e Recurrences in Hamiltonian Systems with Divided Phase Space

By different methods we show that for dynamical chaos in the standard map with critical golden curve the Poincar\'e recurrences P(\tau) and correlations C(\tau) asymptotically decay in time as P ~ C/\tau ~ 1/\tau^3. It is also explained why this asymptotic behavior starts only at very large times. We argue that the same exponent p=3 should be also valid for a general chaos border.Comment: revtex, 4 pages, 3 ps-figure

Quantum Poincar\'e Recurrences

We show that quantum effects modify the decay rate of Poincar\'e recurrences P(t) in classical chaotic systems with hierarchical structure of phase space. The exponent p of the algebraic decay P(t) ~ 1/t^p is shown to have the universal value p=1 due to tunneling and localization effects. Experimental evidence of such decay should be observable in mesoscopic systems and cold atoms.Comment: revtex, 4 pages, 4 figure

Chaos in Spin Clusters: Correlation Functions and Spectral Properties

We investigate dynamic correlation functions for a pair of exchange‐coupled classical spins with biaxial exchange and/or single‐site anisotropy. This represents a Hamiltonian system with two degrees of freedom for which we have previously established the integrability criteria. We discuss the impact of (non‐)integrability on the autocorrelation functions and their spectral properties. We point out the role of long‐time anomalies caused by low‐flux cantori, which dominate the convergence properties of time averages and determine the long‐time asymptotic behavior of autocorrelation functions in nonintegrable cases