Numerical study on active and passive trailing edge morphing applied to a multi-MW wind turbine section

A progressive increasing in turbine dimension has characterized the technological development in offshore wind energy utilization. This aspect reflects on the growing in blade length and weight. For very large turbines, the standard control systems may not be optimal to give the best performance and the best vibratory load damping, keeping the condition of maximum energy production. For this reason, some new solutions have been proposed in research. One of these is the possibility of morphs the blade surface in an active way (increasing the performance in low wind region) or passive (load reduction) way. In this work, we present a numerical study on the active and passive trailing edge morphing, applied to large wind turbines. In particular, the study focuses on the aerodynamic response of a midspan blade section, in terms of fluid structure interaction (FSI) and driven surface deformation. We test the active system in a simple start-up procedure and the passive system in a power production with turbulent wind conditions, that is, two situations in which we expect these systems could improve the performance. All the computations are carried out with a FSI code, which couples a 2D-CFD solver, a moving mesh solver (both implemented in OpenFOAM library) and a FEM solver. We evaluate all the boundary conditions to apply in the section problem by simulating the 5MW NREL wind turbine with the NREL CAE-tools developed for wind turbine simulation

ANALYSIS OF THE TRADITIONAL PASSIVE SYSTEMS PERFORMANCE THROUGH THE APPLICATION OF CFD SOFTWARE

The need to reduce energy consumption is pushing the building design research to the evaluation of passive conditioning systems, since urban buildings are one of the major energy dissipater resulting in emission of CO2. This approach is not modern, but it is historically rooted in the architectural culture of the Mediterranean area and in the Middle East. The passive systems have ancient origins: they were developed to mitigate the summer heat and the winter cold. To understand the reasons that led to the development of passive systems, it should be remembered that about One-Fifth of the emerged planet surface and One-Third of the world's population live in conditions of warm-dry or hot-humid. In addition, most continental areas, even above high values of latitude (50\ub0), are characterized by climatic conditions with summer temperatures over the limit levels of comfort. Nowadays the scientific knowledge and the modern technologies allow to understand the working of passive systems in order to apply them on buildings to improve indoor comfort. This can be obtained through a new approach that involves the elaboration of design strategies based on the development of techniques and on computational and control tools. This work will show the results of a research that aims to verify the working of natural passive cooling systems employed in existing ancient buildings throughout CFD (Computational Fluid Dynamic) software application. Particularly we will define, through computational tools, models and study cases to compare and to set proposals able to actualize the original passive systems conceived and developed in an empirical way

Fully passive Measurement Device Independent Quantum Key Distribution

Measurement-device-independent quantum key distribution (MDI-QKD) can resist all attacks on the detection devices, but there are still some security issues related to the source side. One possible solution is to use the passive protocol to eliminate the side channels introduced by active modulators at the source. Recently, a fully passive QKD protocol has been proposed that can simultaneously achieve passive encoding and passive decoy-state modulation using linear optics. In this work, we propose a fully passive MDI-QKD scheme that can protect the system from both side channels of source modulators and attacks on the measurement devices, which can significantly improve the implementation security of the QKD systems. We provide a specific passive encoding strategy and a method for decoy-state analysis, followed by simulation results for the secure key rate in the asymptotic scenario. Our work offers a feasible way to improve the implementation security of QKD systems, and serves as a reference for achieving passive QKD schemes using realistic devices

Classical Electrodynamics in Quasi-Metric Space-Time

The quasi-metric manifold $\cal N$ is equipped with two one-parameter families of metric tensors ${\bf {\bar g}}_t$ and ${\bf g}_t$, each parametrized by the global time function $t$. Moreover, in $({\cal N},{\bf {\bar g}}_t)$ one must define two different electromagnetic field tensor families corresponding to the active electromagnetic field tensor family ${\bf {\tilde F}}_t$ and the passive electromagnetic field tensor family ${\bf {\bar F}}_t$, respectively. The active electromagnetic field tensor family ${\bf {\tilde F}}_t$ couples to gravity. By construction, the norm of the passive electromagnetic field tensor family ${\bf {\bar F}}_t$ experiences a secular decrease, defining a global cosmic attenuation (not noticeable locally) of the electromagnetic field. Local conservation laws for passive electromagnetism imply that ${\bf {\bar {\nabla}}}{\cdot} {\bf {\bar F}}_t=0$ in electrovacuum, ensuring that photons move on null geodesics of $({\cal N},{\bf {\bar g}}_t)$. From ${\bf {\bar F}}_t$ one may construct the passive electromagnetic field tensor family ${\bf F}_t$ in $({\cal N},{\bf g}_t)$ in the same way as ${\bf g}_t$ is constructed from ${\bf {\bar g}}_t$. This ensures that photons move on null geodesics of $({\cal N},{\bf g}_t)$ as well. As a simple example, the (exact) quasi-metric counterpart to the Reissner-Nordstr\"{o}m solution in General Relativity is calculated. Besides, it is found that a classical charged test particle electromagnetically bound to a central charge will participate in the cosmic expansion. But since quantum-mechanical states should be unaffected by the expansion, this classic calculation is hardly relevant for quantum-mechanical systems such as atoms, so there is no reason to think that the cosmic expansion should apply to them. Finally, it is shown that the main results of geometric optics hold in quasi-metric space-time.Comment: 23 pages, v2: major revision; v3: errors corrected, exact solution found; v4: accepted for publication in G&C; v5: minor corrections pp. 6,18; v6: must have non-universal gravitational coupling; v7: fully coupled theory implemented; v8: fully coupled theory abandone

Discrimination of the Bell states of qudits by means of linear optics

The question of the discrimination of the Bell states of two qudits (i.e., d-dimensional quantum systems) by means of passive linear optical elements and conditional measurements is discussed. A qudit is supposed to be represented by d optical modes containing exactly one photon altogether. From recent results of Calsamiglia it follows that there is no way how to distinguish the Bell states of two qudits for d>2 - not even with the probability of success lower than one - without any auxiliary photons in ancillary modes. Following the results of Carollo and Palma it is proved that it is impossible to distinguish even only one such a Bell state with certainty (i.e., with the probability of success equal to one), irrespective of how many auxiliary photons are involved. However, it is shown that auxiliary photons can help to discriminate the Bell states of qudits with the high probability of success: A Bell-state analyzer based on the idea of linear optics quantum computation that can achieve the probability of success arbitrarily close to one is described. It requires many auxiliary photons that must be first "combined" into entangled states.Comment: 4 pages, 5 figure

TUNING TO ROAD AND LOAD PASSIVE SUSPENSIONS MULTI-MODELLING AND OPTIMISATION

This work explores the ability to apply multi-modeling technique of new suspension system based on a shock absorber model VZN (European Patent 1190184/20052). Here are presented the results of their own scientific research on the multi-modelling a auto vehicles suspension systems based on passive hydraulic shock absorbers with variable damping characteristics depending on the position of the sprung mass and road conditions. For such a system was proposed and verified by in Matlab-Simulink simulation, a procedure for optimizing the damping characteristics of the road conditions and load given. Suspension system is represented by a quarter-car multi-model with one degree of freedom and representative way perturbation by white noise. Proposed new criterion function in optimisation self-adaptive passive suspension

Passive decoy state quantum key distribution with practical light sources

Decoy states have been proven to be a very useful method for significantly enhancing the performance of quantum key distribution systems with practical light sources. While active modulation of the intensity of the laser pulses is an effective way of preparing decoy states in principle, in practice passive preparation might be desirable in some scenarios. Typical passive schemes involve parametric down-conversion. More recently, it has been shown that phase randomized weak coherent pulses (WCP) can also be used for the same purpose [M. Curty {\it et al.}, Opt. Lett. {\bf 34}, 3238 (2009).] This proposal requires only linear optics together with a simple threshold photon detector, which shows the practical feasibility of the method. Most importantly, the resulting secret key rate is comparable to the one delivered by an active decoy state setup with an infinite number of decoy settings. In this paper we extend these results, now showing specifically the analysis for other practical scenarios with different light sources and photo-detectors. In particular, we consider sources emitting thermal states, phase randomized WCP, and strong coherent light in combination with several types of photo-detectors, like, for instance, threshold photon detectors, photon number resolving detectors, and classical photo-detectors. Our analysis includes as well the effect that detection inefficiencies and noise in the form of dark counts shown by current threshold detectors might have on the final secret ket rate. Moreover, we provide estimations on the effects that statistical fluctuations due to a finite data size can have in practical implementations.Comment: 17 pages, 14 figure

Numerical study on active and passive trailing edge morphing applied to a multi-MW wind turbine section

A progressive increasing in turbine dimension has characterized the technological evelopment in offshore wind energy utilization. This aspect reflects on the growing in blade length and weight. For very large turbines, the standard control systems may not be optimal to give the best performance and the best vibratory load damping, keeping the condition of maximum energy production. For this reason, some new solutions have been proposed in research. One of these is the possibility of morphs the blade surface in an active way (increasing the performance in low wind region) or passive (load reduction) way. In this work, we present a numerical study on the active and passive trailing edge morphing, applied to large wind turbines. In particular, the study focuses on the aerodynamic response of a midspan blade section, in terms of fluid structure interaction (FSI) and driven surface deformation. We test the active system in a simple start-up procedure and the passive system in a power production with turbulent wind conditions, that is, two situations in which we expect these systems could improve the performance. All the computations are carried out with a FSI code, which couples a 2D-CFD solver, a moving mesh solver (both implemented in OpenFOAM library) and a FEM solver. We evaluate all the boundary conditions to apply in the section problem by simulating the 5MW NREL wind turbine with the NREL CAE-tools developed for wind turbine simulation