A stability criterion for systems with neutrally stable modes and deadzone nonlinearities

Stability analysis is considered for feedback interconnections of deadzone nonlinearities with linear systems that has a neutrally stable mode. Such systems do not have a unique equilibrium point and the standard techniques from passivity and Lyapunov theory cannot be applied. A stability criterion that generalizes the Popov criterion for this class of systems is derived in this report and several examples will prove its applicability

Український вчений, громадський діяч І. А. Фещенко-Чопівський

(uk) Ця публікація розкриває цілісну канву життєдіяльності І.Фещенка-Чопівського, показує його як політика, дипломата, ученого, видатного українця, котрий органічно увібрав українську культуру, національний характер і до останніх днів не втратив почуття національної гідності й віри в державотворчі сили свого народу.(en) The life activity of I. Feshenco-Chopivscogo is considered in the article. The publication shows him as a politician, a diplomat and an outstanding Ukrainian. His personality harmoniously absorbed the Ukrainian culture and national character. He didn’t lose the feeling of national dignity and deep faith in the ability of his nation to build the State

URWARE Wastewater Treatment Plant Models

In this document, a large number of mathematical models describing various physical, biological and chemical processes in a wastewater treatment plant are presented. In most cases, the models are fairly simple as they are inteded for steady-state simulations based on yearly averages of the influent wastewater charteristics. The combination of models forms a software tool namned URWARE (URban WAter REsearch model), which is a tool for substance flow analysis and energy calculations in wastewater treatment systems. All models are based on the MATLAB/Simulink platform. The different models can be combined in any fashion thereby creating various system structures that can be analysed and compared. The models keep track of numerous substances related to wastewater, such as organic substances, nutrients and to some extent heavy metals. Within all models the release of environmentally hazardous substances to water, soil and air are calculated. The results can be used as one (of many) information pathways for strategic decision making related to urban water systems. The individual models are described one by one and their behaviours are exemplified by simulation results. In many cases, comparisons with other available software models are given to validate (or at least make plausible) the results produced by the fairly simple URWARE models. Simulation results based on a combination of models into a complete wastewater treatment plant are also presented. However, details about the underlying theory and hypotheses on which the models are based cannot always be sufficiently described due to space limitations. Moreover, users should always be critical to any results predicted by models and not take them for granted simply because they have been calculated by a computer model. Knowledge about the real processes and comparisons with real data are imperative to evaluate whether the predicted results are reasonable or not. For the interested reader the complete source code to all models is included in an extensive appendix. A modelling task of this magnitude is never completed. The proposed models can always be further developed, improved and refined. Consequently, the models described in this document only represent the first version of the URWARE software. Many issues remain to be solved and further improvements to be done. However, it is the hope of the authors that the presented models are mature enough to be used, evaluated, modified and improved by other users outside the URWARE task group

Stability of Systems Under Interference Feedback

Abstract-Distributed power control problems in wireless communication can be modeled as a highly nonlinear feedback system. The nonlinear coupling appear when a large number of mobile stations interact through interference and it is well known that this may lead to instabilities. In this paper a number of results on existence and uniqueness of solution and boundedness and convergence of the solution are derived for systems with higher order control loops

Swedish LifeWatch ─ a biodiversity infrastructure integrating and reusing data from citizen science, monitoring and research

With continued pressure on biodiversity and ever-growing conflicts with human development, qualified systems for scenario modelling, impact assessment and decision support are urgently needed. Such systems must be able to integrate complex models and information from many sources and do so in a flexible and transparent way. To that end, as well as for other complicated and data-intensive biodiversity research purposes, the concept of LifeWatch has emerged. The idea of LifeWatch is to construct e-infrastructure and virtual laboratories by integrating large data sources, computational capacities, and tools for analysis and modelling in an open, serviceoriented architecture. To be efficient and accurate, a continuous inflow of large quantities of data is essential. However, even with new techniques, government-funded monitoring data and research data will not feed the system with up-to-date species information of sufficient scale and resolution. To fill this void, skilled amateur observers (citizen scientists) can contribute to a very valuable extent. After a preparatory phase, a Swedish LifeWatch (SLW) consortium was initiated in 2011. Swedish LifeWatch developed an infrastructure where all components are accessible through open web services. At the SLW Analysis portal, different formats of species and environmental data can be accessed instantly, and integrated, analysed, visualized and downloaded at selected temporal, spatial or taxonomic scales. Swedish LifeWatch currently provides 46 million species observations from eight different databases, all harmonized according to standardized formats and the Dyntaxa taxonomic backbone database. Almost 40 million of these observations were provided by citizens through the online reporting system named the Species Observation System (SOS) or Artportalen. This paper describes this system, as well as the incentives that make it so successful. The citizen science data in the SOS are accessible, together with data from research and monitoring, in the SLW infrastructure, making the latter a powerful instrument for large-scale data extraction, visualization and analysis