On Norm-Based Estimations for Domains of Attraction in Nonlinear Time-Delay Systems

For nonlinear time-delay systems, domains of attraction are rarely studied despite their importance for technological applications. The present paper provides methodological hints for the determination of an upper bound on the radius of attraction by numerical means. Thereby, the respective Banach space for initial functions has to be selected and primary initial functions have to be chosen. The latter are used in time-forward simulations to determine a first upper bound on the radius of attraction. Thereafter, this upper bound is refined by secondary initial functions, which result a posteriori from the preceding simulations. Additionally, a bifurcation analysis should be undertaken. This analysis results in a possible improvement of the previous estimation. An example of a time-delayed swing equation demonstrates the various aspects.Comment: 33 pages, 8 figures, "This is a pre-print of an article published in 'Nonlinear Dynamics'. The final authenticated version is available online at https://doi.org/10.1007/s11071-020-05620-8

Robustness Analysis with Respect to Exogenous Perturbations for Flatness-Based Exact Feedforward Linearization

A methodology to analyze robustness with respect to exogenous perturbations for exact feedforward linearization based on differential flatness is presented. The analysis takes into consideration the tracking error equation and makes thereafter use of a stability result by Kelemen coupled with results issued from interval analysis. This turns exact feedforward linearization based on differential flatness into a general control methodology for flat systems

E=MC3 Energy Equals Management\u27s Continued Cost Concerns

E=MC³ Energy Equals Management\u27s Continued Cost Concern, is an essay written by Fritz G. Hagenmeyer, Associate Professor, School of Hospitality Management at Florida International University. In the writing, Hagenmeyer initially tenders: “Energy problems in the hospitality industry can be contained or reduced, yielding elevated profits as a result of applied, quality management principles. The concepts, processes and procedures presented in this article are intended to aid present and future managers to become more effective with a sharpened focus on profitability.” This article is an overview of energy efficiency and the management of such. In an expanding energy consumption market with its escalating costs, energy management has become an ever increasing concern and component of responsible hospitality management, Hagenmeyer will have you know. “In endeavoring to manage on a day-to-day basis a functioning hospitality building\u27s energy system, the person in charge must take on the role of Justice with her scales, attempting to balance the often varying comfort needs of guests and occupants with the invariable rising costs of energy utilized to generate and maintain such comfort conditions, since comfort is seen as an integral part of the service, product, or price/value” perception of patrons,” says Hagenmeyer. In contrast to what was thought in the mid point of this century - that energy would be abundant and cheap - the reality has set-in that this is not the case; not by a long shot. The author wants you to be aware that energy costs in buildings are a force to be reckoned with; a major expense to be sure. “Since 1973, energy-conscious design has begun to become part of the repertoire of architects, design engineers, and construction companies,” Hagenmeyer states. “For instance, whereas office buildings of the early 1970s might have used 400,000 British Thermal Units (BTUs) per square foot year, new buildings are going up that use 55,000 to 65,000 BTUs per square foot year,” Hagenmeyer, like an incandescent bulb, illuminates you. Hagenmeyer references Robert E. Aulbach’s article - Energy Management – when informing you that the hospitality manager should not become complacent in addressing the energy cost issue, but should and must maintain a diligent focus on the problem. Hagenmeyer also makes reference to the Middle East War and to OPEC, and their influence on energy prices. In closing, Hagenmeyer suggests an - Energy Management Action Plan – which he outlines for you

Using Open Data for Modeling and Simulation of the All Electrical Society in eASiMOV

The present study examines a future energy systems scenario, the so-called All Electrical Society (AES), which is defined by a very high number of active prosumers in the distribution grid in view of future 100% renewables-based energy systems. In this paper, we present data modeling methods that describe the power consumption behavior and power generation patterns via time series for 78 prosumers, each fully equipped with rooftop PV, two battery electrical vehicles and a heat pump. Quasi-dynamic simulations of a low voltage grid under stress conditions are performed using open data and free software. The simulatively determined increase in network utilization and congestion is also compared with the currently available grid capacity gained through extensive measurements in the examined distribution grid. The result is that in the AES scenario the current deployed electrical infrastructure of the distribution grid will be more than heavily overloaded, both the transformers and the respective power lines

Distribution Grid Monitoring Based on Widely Available Smart Plugs

During the last few years, smart home devices have become increasingly popular. Smart plugs, smart lights, and smart switches are now found in as many as 37 percent of German households, and the popularity of these devices is rising. Smart devices sometimes also integrate sensors for measuring voltage and current. The increase in renewable generation, e-mobility and heat pumps lead to scenarios for which the distribution grid was not originally designed. Moreover, parts of the distribution grid are only sparsely instrumented, which leaves the distribution grid operator unaware of possible bottlenecks resulting from the introduction of such loads and renewable generation. To overcome this lack of information, we propose a grid monitoring that is based on measurements of widely available smart home devices, such as smart plugs. In the present paper, we illustrate the collection and utilization of smart plug measurements for distribution grid monitoring and examine the extent and effect of measurement inaccuracy. For this evaluation, we analyze the measurements of multiple commercially available smart plugs and test the effect of measurement errors on the monitoring when using a single smart plug.Comment: 8 pages