Ernst & Young's biennial national water and wastewater rate surveys collect information on bills, rate structures, billing cycles, and special charges for utilities serving the 100 largest metropolitan statistical areas in the United States. This article presents trends and patterns observed in these surveys, which have been conducted since 1986, and provides a discussion of national and regional pricing trends supported by the survey results. The most significant trend evidenced from the surveys is a shift toward conservation rate structures, which promote more efficient use of water resources through use of uniform and inverted‐block rates, seasonal and excess‐use surcharges, and in some cases, marginal cost pricing.
Prolonged periods from conception to deployment of a satellite can undermine a time dependent mission. Currently, the timeline for a new satellite to reach deployment is on the order of years. The need for a more efficient process is evident and has lead to innovations at every aspect of satellite design and pre-launch testing. One such example is the development of panels and components that are prefabricated for space flight and capable of assembly in a variety of configurations. However, all final systems regardless of component qualification must be validated for space flight. Current qualification testing can take weeks to years. An ultrasonic technique based on the energy of a transmitted wave across the connection is intended either as an alternative to traditional vibration=qualification testing or as a precursor to in-situ monitoring of panel-to-panel connections. Transmitted elastic wave energy is used to assess the integrity of the connection in reference to an initially established baseline. An experiment was conducted on a functional satellite to test the feasibility of deploying this test method under realistic circumstances. A second experiment was conducted to test the repeatability of the test method and to find an appropriate range of test parameters.
A system’s response to disturbances in an internal or external driving signal can be characterized as performing an implicit computation, where the dynamics of the system are a manifestation of its new state holding some memory about those disturbances. Identifying small disturbances in the response signal requires detailed information about the dynamics of the inputs, which can be challenging. This paper presents a new method called the Information Impulse Function (IIF) for detecting and time-localizing small disturbances in system response data. The novelty of IIF is its ability to measure relative information content without using Boltzmann’s equation by modeling signal transmission as a series of dissipative steps. Since a detailed expression of the informational structure in the signal is achieved with IIF, it is ideal for detecting disturbances in the response signal, i.e., the system dynamics. Those findings are based on numerical studies of the topological structure of the dynamics of a nonlinear system due to perturbated driving signals. The IIF is compared to both the Permutation entropy and Shannon entropy to demonstrate its entropy-like relationship with system state and its degree of sensitivity to perturbations in a driving signal.
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