Large Current Fluctuations Research Articles

Lake surface fluctuations and the mass flow through the narrows of Lake Winnipeg

Lake Winnipeg is a large (23,000 km2), shallow (12 m), homogeneous lake composed of two well defined basins separated by a central area of irregular geometry that includes the Narrows. Lake current was measured at 3 depths from two moorings in the Narrows and was compared with water level records from 7 gauges around the lake throughout the ice free season (May 15–October 15, 1976). The dominant lake response was a forced response produced by natural fluctuations in the wind with periods of 50–100 hours. Large amplitude water level and current fluctuations were produced by low wind speeds due to resonance caused by wind periodicity near the 39 hour natural cobasin oscillation of the lake. Although damping is subcritical, allowing for a resonant response, Lake Winnipeg is heavily damped compared to deep lakes. The cobasin oscillation is so low in frequency that a classical wind setup is unlikely to occur. Free oscillations were of secondary importance to the large scale dynamics of the lake. Several whole lake modes higher than the first were identified from the current and water level records but the amplitudes of these modes were very small compared to the free response of the Great Lakes. There was also a detectable response in the records at several natural frequencies of the individual basins and at the M2 tide.

Erratum: “Noise Spectrum of a Nonlinear Oscillator Driven by Periodic and Random Forces”

The spectrum intensity of the current of nonlinear resonance circuit driven by random and periodic voltages is investigated by solving two dimensional Langevin equations approximately, and the occurrence of a large current fluctuation is expected in a certain range of frequency. This phenomenon is also verified experimentally by observing the current noise in a nonlinear resonance circuit, which is composed of an ordinary inductance and a nonlinear capacitor made from ferroelectric tri-glycine sulphate.

Noise Spectrum of a Nonlinear Oscillator Driven by Periodic and Random Forces

The spectrum intensity of the current of nonlinear resonance circuit driven by random and periodic voltages is investigated by solving two dimensional Langevin equations approximately, and the occurrence of a large current fluctuation is expected in a certain range of frequency. This phenomenon is also verified experimentally by observing the current noise in a nonlinear resonance circuit, which is composed of an ordinary inductance and a nonlinear capacitor made from ferroelectric tri-glycine sulphate.