Deep Lagrangian Networks for end-to-end learning of energy-based control for under-actuated systems

Applying Deep Learning to control has a lot of potential for enabling the intelligent design of robot control laws. Unfortunately common deep learning approaches to control, such as deep reinforcement learning, require an unrealistic amount of interaction with the real system, do not yield any performance guarantees, and do not make good use of extensive insights from model-based control. In particular, common black-box approaches -- that abandon all insight from control -- are not suitable for complex robot systems. We propose a deep control approach as a bridge between the solid theoretical foundations of energy-based control and the flexibility of deep learning. To accomplish this goal, we extend Deep Lagrangian Networks (DeLaN) to not only adhere to Lagrangian Mechanics but also ensure conservation of energy and passivity of the learned representation. This novel extension is embedded within generic model-based control laws to enable energy control of under-actuated systems. The resulting DeLaN for energy control (DeLaN 4EC) is the first model learning approach using generic function approximation that is capable of learning energy control. DeLaN 4EC exhibits excellent real-time control on the physical Furuta Pendulum and learns to swing-up the pendulum while the control law using system identification does not.Comment: Published at IROS 201

Selection by higher-order effects of salinity and bacteria on early life-stages of Western Baltic spring-spawning herring

Habitat stratification by abiotic and biotic factors initiates divergence of populations and leads to ecological speciation. In contrast to fully marine waters, the Baltic Sea is stratified by a salinity gradient that strongly affects fish physiology, distribution, diversity and virulence of important marine pathogens. Animals thus face the challenge to simultaneously adapt to the concurrent salinity and cope with the selection imposed by the changing pathogenic virulence. Western Baltic spring-spawning herring (Clupea harengus) migrate to spawning grounds characterized by different salinities to which herring are supposedly adapted. We hypothesized that herring populations do not only have to cope with different salinity levels but that they are simultaneously exposed to higher-order effects that accompany the shifts in salinity, that is induced pathogenicity of Vibrio bacteria in lower saline waters. To experimentally evaluate this, adults of two populations were caught in their spawning grounds and fully reciprocally crossed within and between populations. Larvae were reared at three salinity levels, representing the spawning ground salinity of each of the two populations, or Atlantic salinity conditions resembling the phylogenetic origin of Clupea harengus. In addition, larvae were exposed to a Vibrio spp. infection. Life-history traits and gene expression analysis served as response variables. Herring seem adapted to Baltic Sea conditions and cope better with low saline waters. However, upon a bacterial infection, herring larvae suffer more when kept at lower salinities implying reduced resistance against Vibrio or higher Vibrio virulence. In the context of recent climate change with less saline marine waters in the Baltic Sea, such interactions may constitute key future stressors

1. Wochenbericht AL569

1. Wochenbericht FS Alkor Reise 569, Fahrtabschnitt 02.03.-05.03.202

Assessing marine phytoplankton eco-evolutionary dynamics and physiological responses to environmental change

Anthropogenic emissions of carbon dioxide (CO2) resulting from fossil fuel burning and changes in land use are affecting our marine environment; for example leading to ocean acidification or ocean warming. In order to understand how climate change will affect biological communities we need to understand all levels of biological responses. Community change as a response to environmental drivers are composed of three components: the physiological responses within an organism, described by its phenotypic plasticity or reaction norm and the ecological and evolutionary responses which are associated with changes on the species and genotype level, respectively. Moreover, there may be eco-evolutionary coupling, thus either ecological interactions such as competition that modify evolutionary responses to physico-chemical changes, or evolutionary change that feeds back to change ecological interactions. Here I study for the first time over the long-term (up to 220 generations) how among two competing phytoplankton species the different response types play out, and whether or not coupling of ecological and evolutionary processes can be found. Additionally I investigated the short-term inter- and intraspecific responses of three phytoplankton species to increased CO2 and what role competitive interactions play on the short-term in a two-species ´community´

Bachelor-MARSYS education cruise in the Baltic Sea Cruise No. AL551

06.03 – 13.03.2021, Kiel (Germany) – Kiel (Germany) BALTEACH -

Euroopa Liidu küberjulgeoleku strateegia rakendamine küberrünnakute korral Eesti kriitilise infrastruktuuri näitel

Käesoleva töö eesmärgiks on Euroopa Liidu küberjulgeoleku strateegiast lähtuvalt võrrelda Eesti kriitilise infrastruktuuriga ettevõtete ja Eesti riigi küberjulgeoleku strateegiaid küberrünnakute eest kaitsmisel. Töö eesmärki aitavad saavutada neli uurimisküsimust, mis selgitavad küberjulgeoleku kujunemist, avaliku sektori ja erasektori koostööd, küberrünnakute liigitust ning kriitilise infrastruktuuri olemust ja kaitse vajalikkust. Teoreetilistest käsitlustest kasutatakse klassikalise julgeoleku kompleksi ning Kopenhaageni koolkonna teooriat. Töö eesmärki aitavad saavutada kvalitatiivsetest uurimismeetoditest dokumentide analüüs ning poolstruktureeritud ekspertintervjuud. Dokumentide analüüsimisel võrreldi Euroopa Liidu ja Eesti küberjulgeoleku strateegiaid, mille tulemusena selgus strateegiate sarnasus ning rõhuasetus kriitilisele infrastruktuurile. Ekspertintervjuud viidi läbi seitsme energia ning telekommunikatsiooni ettevõtte eksperdi seas, mille tulemusel toodi peamiste kitsaskohtadena välja koostöö puudulikkus, avaliku sektori killustatus, investeeringute vähesus küberkaitsesse ning küberjulgeoleku teadlikkuse madal tase. Peamiste ettepanekutena soovitati suurendada avaliku sektori ja erasektori koostööd läbi koolituste, infopäevade ning regulaarsete kohtumiste. Riigi Infosüsteemi Amet võiks edastada kriitilise infrastruktuuriga ettevõtetele kord poolaastas informatsiooni aktuaalsetest küberohtudest ning riik teavitada ettevõtteid Euroopa Liidus toimuvatest konverentsidest, parima praktika vahetamise võimalustest ja rahvusvahelistest koolitustest. Riik võiks lisaks omalt poolt küberjulgeoleku valdkonda rohkem politiseerida ning seeläbi tagada suurem investeeringute maht küberkaitsesse. Edaspidistes uurimustes võib uurida spetsiifilisemalt iga kriitilise infrastruktuuri valmisolekut küberrünnakuteks või seoses direktiivi peatse vastu võtmisega kaasnevaid kohustusi riigile, kriitilise infrastruktuuri ettevõtetele.http://www.ester.ee/record=b449979

Eco-Evolutionary Interaction in Competing Phytoplankton: Nutrient Driven Genotype Sorting Likely Explains Dominance Shift and Species Responses to CO2

How ecological and evolutionary processes interact and together determine species and community responses to climate change is poorly understood. We studied long-term dynamics (over approximately 200 asexual generations) in two phytoplankton species, a coccolithophore (Emiliania huxleyi), and a diatom (Chaetoceros affinis), to increased CO2 growing alone, or competing with one another in co-occurrence. To allow for rapid evolutionary responses, the experiment started with a standing genetic variation of nine genotypes in each of the species. Under co-occurrence of both species, we observed a dominance shift from C. affinis to E. huxleyi after about 120 generations in both CO2 treatments, but more pronounced under high CO2. Associated with this shift, we only found weak adaptation to high CO2 in the diatom and none in the coccolithophore in terms of species’ growth rates. In addition, no adaptation to interspecific competition could be observed by comparing the single to the two-species treatments in reciprocal assays, regardless of the CO2 treatment. Nevertheless, highly reproducible genotype sorting left only one genotype remaining for each of the species among all treatments. This strong evolutionary selection coincided with the dominance shift from C. affinis to E. huxleyi. Since all other conditions were kept constant over time, the most parsimonious explanation for the dominance shift is that the strong evolutionary selection was driven by the experimental nutrient conditions, and in turn potentially altered competitive ability of the two species. Thus, observed changes in the simplest possible two-species phytoplankton “community” demonstrated that eco-evolutionary interactions can be critical for predicting community responses to climate change in rapidly dividing organisms such as phytoplankton

Inter- and intraspecific phenotypic plasticity of three phytoplankton species in response to ocean acidification

Phenotypic plasticity describes the phenotypic adjustment of the same genotype to different environmental conditions and is best described by a reaction norm. We focus on the effect of ocean acidification on inter- and intraspecific reaction norms of three globally important phytoplankton species (Emiliania huxleyi, Gephyrocapsa oceanica and Chaetoceros affinis). Despite significant differences in growth rates between the species, they all showed a high potential for phenotypic buffering (similar growth rates between ambient and high CO2 conditions). Only three coccolithophore genotypes showed a reduced growth in high CO2. Diverging responses to high CO2 of single coccolithophore genotypes compared with the respective mean species responses, however, raise the question of whether an extrapolation to the population level is possible from single-genotype experiments. We therefore compared the mean response of all tested genotypes with a total species response comprising the same genotypes, which was not significantly different in the coccolithophores. Assessing species reaction norms to different environmental conditions on short time scale in a genotype-mix could thus reduce sampling effort while increasing predictive power

Master-Slave Synchronization for Nonlinear Systems based on Reduced Observers

In this article a global method for master-slave synchronization of nonlinear systems is provided. Based on a diffeomorphic transformation of the original dynamics, a reduced observer is designed such that the nonlinear state feedback law is independent of the inertial frame. Generally, the method requires non trivial computations but leads to global convergence results for the invariant tracking error. We illustrate the design procedure in detail for a master-slave synchronization of a bacterial growth model, which may escape to infinity in finite time