On the Strong Coupling Limit of Many-Polaron Systems in Electromagnetic Fields

In this paper estimates on the ground state energy of Fr\"ohlich $N$-polarons in electromagnetic fields in the strong coupling limit, $\alpha\to\infty$, are derived. It is shown that the ground state energy is given by $\alpha^2$ multiplied by the minimal energy of the corresponding Pekar-Tomasevich functional for $N$ particles, up to an error term of order $\alpha^{42/23}N^3$. The potentials $A,V$ are suitably rescaled in $\alpha$. As a corollary, binding of $N$-polarons for strong magnetic fields for large coupling constants is established

Mitigating the negative impacts of tall wind turbines on bats: Vertical activity profiles and relationships to wind speed.

Wind turbines represent a source of hazard for bats, especially through collision with rotor blades. With increasing technical development, tall turbines (rotor-swept zone 50-150 m above ground level) are becoming widespread, yet we lack quantitative information about species active at these heights, which impedes proposing targeted mitigation recommendations for bat-friendly turbine operation. We investigated vertical activity profiles of a bat assemblage, and their relationships to wind speed, within a major valley of the European Alps where tall wind turbines are being deployed. To monitor bat activity we installed automatic recorders at sequentially increasing heights from ground level up to 65 m, with the goal to determine species-specific vertical activity profiles and to link them to wind speed. Bat call sequences were analysed with an automatic algorithm, paying particular attention to mouse-eared bats (Myotis myotis and Myotis blythii) and the European free-tailed bat (Tadarida teniotis), three locally rare species. The most often recorded bats were the Common pipistrelle (Pipistrellus pipistrellus) and Savi's pipistrelle (Hypsugo savii). Mouse-eared bats were rarely recorded, and mostly just above ground, appearing out of risk of collision. T. teniotis had a more evenly distributed vertical activity profile, often being active at rotor level, but its activity at that height ceased above 5 ms-1 wind speed. Overall bat activity in the rotor-swept zone declined with increasing wind speed, dropping below 5% above 5.4 ms-1. Collision risk could be drastically reduced if nocturnal operation of tall wind turbines would be restricted to wind speeds above 5 ms-1. Such measure should be implemented year-round because T. teniotis remains active in winter. This operational restriction is likely to cause only small energy production losses at these tall wind turbines, although further analyses are needed to assess these losses precisely

Piecewise-Steady-State Modelica Simulations for the Conceptual Design Phase of Industrial Processes

The conceptual design of industrial processes is challenging as relatively little information about the eventually selected equipment and their operation is known in this early design stage. Furthermore, the systems are increasingly integrated with themselves, and their design must be addressed systematically. Simulation can assist in better understanding the effects of design decisions on the resulting system performance. To facilitate the simulation of industrial processes in this early design phase, this paper proposes an approach to modeling system components specifically aimed at employing known key design parameters and assuming steady-state behavior of the process for a certain period of time (e.g. one hour). A solution over a longer period of time (e.g. for a year) can then be obtained by simulating a multitude of such shorter periods, leading to the piecewise-steady-state solution. The proposed approach is developed with an exemplary case study, based on a real industrial site. The resulting model computes the annual load profile within the range of seconds for the given case study

On the Magnetic Pekar Functional and the Existence of Bipolarons

First, this paper proves the existence of a minimizer for the Pekar functional including a constant magnetic field and possibly some additional local fields that are energy reducing. Second, the existence of the aforementioned minimizer is used to establish the binding of polarons in the model of Pekar-Tomasevich including external fields.Comment: 13 page

Solvation Layer of Antifreeze Proteins Analyzed with a Markov State Model

Three structurally very different antifreeze proteins (AFPs) are studied, addressing the question as to what extent the hypothesized preordering-binding mechanism is still relevant in the second solvation layer of the protein and beyond. Assuming a two-state model of water, the solvation layers are analyzed with the help of molecular dynamics simulations together with a Markov state model, which investigates the local tedrahedrality of the water hydrogen-bond network around a given water molecule. It has been shown previously that this analysis can discriminate the high-entropy, high-density state of the liquid (HDL) from its more structured low-density state (LDL). All investigated proteins, regardless of whether they are an AFP or not, have a tendency to increase the amount of HDL in their second solvation layer. The ice binding site (IBS) of the antifreeze proteins counteracts that trend, with either a hole in the HDL layer or a true excess of LDL. The results correlate to a certain extent with recent experiments, which have observed ice like vibrational (VSFG) spectra for the water atop the IBS of only a subset of antifreeze proteins. It is concluded that the preordering-binding mechanism indeed seems to play a role but is only part of the overall picture

Heat pump integration in non-continuous industrial processes by Dynamic Pinch Analysis Targeting

A key strategy for the transition towards a low-carbon economy is the electrification of industrial heat. Heat pumps can recover and upgrade excess or waste heat. They present a highly efficient component to decarbonize process heating. In Pinch Analysis, most approaches to design the heat recovery system as well as the utility system are based on a single operating point or a couple of operating point. In the past, this was due to the lack of temporally detailed process data. However, the available process data is expected to increase drastically by the use of transient process simulation models. Thus, a method is needed which interprets the data correctly and assists with design choices. This study proposes a methodology for the design and sizing of a heat pump based on the simulated annual process data of an industrial process. Three approaches are explored: (1) the conventional approach for heat pump integration by application of the Time Average Model (TAM), (2) an approach that investigates the optimal heat pump parameters for each data point by the principles of Pinch Analysis and mathematical optimization and (3) an optimization method, which considers the entire annual process data as well as thermo-economic objectives such as net present value (NPV) and internal rate of return (IRR). The new methodology compared to the conventional TAM approach is able to design a 33 % smaller heat pump, which reduces the annual operating cost by an additional 2.2 %. The NPV and IRR are more than tripled

Comparison of DVB-T Passive Radar Simulated and Measured Bistatic RCS Values for a Pilatus PC-12 Aircraft

Passive radar is a technology that has huge potential for airspace monitoring, taking advantage of existing transmissions. However, to predict whether particular targets can be measured in a particular scenario, it is necessary to be able to model the received signal. In this paper, we present the results of a campaign in which a Pilatus PC-12 single-engine aircraft was measured with a passive radar system relying on DVB-T transmission from a single transmitter. We then present our work to simulate the bistatic RCS of the aircraft along its flight track, using both the method of moments and the shooting and bouncing ray solvers, assess the uncertainty in the simulations, and compare against the measurements. We find that our simulated RCS values are useful in predicting whether or not detection occurs. However, we see poor agreement between simulated and measured RCS values where measurements are available, which we attribute primarily to the difficulties in extracting RCS measurements from the data and to unmodeled transmission and received path effects

Practical heat pump and storage integration into non-continuous processes: A hybrid approach utilizing insight based and nonlinear programming techniques

This paper focuses on industrial heat pump (HP) integration in non-continuous processes. To achieve the necessary time-wise process decoupling of the HP system, heat recovery loops (HRLs) with stratified storages are used. This design type can be modeled as a mixed integer nonlinear programming problem which often results in expensive mathematical formulations. The challenge is addressed by a practical method that combines the insight based approach of Pinch Analysis with mathematical programming techniques to give the engineer more flexibility for the application of the method and to avoid long computation times. By the use of the insight based methods, the solution space of the mathematical formulation is restricted, and thus its complexity is reduced to a nonlinear programming problem optimizing the temperature levels in the HP-HRL system. As an objective, total annual costs (TAC) of the HP-HRL system are minimized. The developed hybrid method is applied to a dairy site and compared in terms of approach temperatures, temperature lift of the HP, TAC, and greenhouse gas emissions to the existing methods. It is shown, that the hybrid method provides realistic approach temperatures in contrast to the existing insight based method