Small Wind Turbines: Specification, Design, and Economic Evaluation

In this work, we consider various aspects of small wind turbines’ (SWTs) design and operation. First, an extensive literature study is presented by considering SWTs specification, market statistics, the smart grid, and the prosumer concepts as well as the most important parameters affecting the efficiency of wind turbines. Then, both the literature review and series of coupled numerical simulations investigating impact of the chosen design solutions on small wind turbine operation are performed. It allowed objective evaluation of different design approaches, which in turn enabled the systematic identification of actual limitations as well as the opportunities for specific design solutions of SWTs: horizontal axis wind turbines (HAWTs) and vertical axis wind turbines (VAWTs); the rotor position in relation to the tower (upwind vs. downwind); and diffusor-augmented wind turbine (DAWT). Additionally, an economic evaluation is carried with the use of an advanced numerical Weather Research & Forecasting (WRF) model. It is shown that auxiliary power generation using privately owned SWTs can be an economically viable option. Finally, a set of design goals for future SWTs is formulated based on the performed numerical analyses

Small wind turbine augmentation: Experimental investigations of shrouded- and twin-rotor wind turbine systems

An increase in the efficiency of Small Wind Turbines (SWTs) by aerodynamic optimisation of the blade geometry is limited (low Reynolds number influence). Solutions such as the Diffuser-Augmented Wind Turbine (DAWT) and the twin-rotor systems are of increasing interest. A diffuser promotes an increase in the wind mass flow rate through the turbine, whereas an auxiliary rotor enables extraction of the wind kinetic energy in the wake. The paper summarizes the measurements of wind turbine systems performance conducted at the Institute of Turbomachinery, Lodz University of Technology (IMP TUL). The research incorporated a spectrum of wind turbine configurations for open and shrouded, single- and twin-rotor systems. The objective was to compare the performance of the same rotor in different configurations. The influence of a low Reynolds number flow on the rotor performance is also discussed and quantified. The study shows that, while augmenting the wind turbine performance (as much as twofold increase), shrouding rises significantly the rotor loading. A remedy for that may be an application of the second rotor. Although it provides a rather modest efficiency increase (11–13% for the unshrouded-, 4–5% for shrouded turbine), it allows loads to be distributed more evenly on turbines

The operational window of carbon nanotube electrical wires treated with strong acids and oxidants

Conventional metal wires suffer from a significant degradation or complete failure in their electrical performance, when subjected to harsh oxidizing environments, however wires constructed from Carbon Nanotubes (CNTs) have been found to actually improve in their electrical performance when subjected to these environments. These opposing reactions may provide new and interesting applications for CNT wires. Yet, before attempting to move to any real-world harsh environment applications, for the CNT wires, it is essential that this area of their operation be thoroughly examined. To investigate this, CNT wires were treated with multiple combinations of the strongest acids and halogens. The wires were then subjected to conductivity measurements, current carrying capacity tests, as well as Raman, microscopy and thermogravimetric analysis to enable the identification of both the limits of oxidative conductivity boosting and the onset of physical damage to the wires. These experiments have led to two main conclusions. Firstly, that CNT wires may operate effectively in harsh oxidizing environments where metal wires would easily fail and secondly, that the highest conductivity increase of the CNT wires can be achieved through a process of annealing, acetone and HCl purification followed by either H2O2 and HClO4 or Br2 treatment

Monte Carlo simulations of ion channeling in crystals containing dislocations and randomly displaced atoms

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Ultrafast optical circuit switching for data centers using integrated soliton microcombs

Networks inside current data centers comprise a hierarchy of power-hungry electronic packet switches interconnected via optical fibers and transceivers. As the scaling of such electrically-switched networks approaches a plateau, a power-efficient solution is to implement a flat network with optical circuit switching (OCS), without electronic switches and a reduced number of transceivers due to direct links among servers. One of the promising ways of implementing OCS is by using tunable lasers and arrayed waveguide grating routers. Such an OCS-network can offer high bandwidth and low network latency, and the possibility of photonic integration results in an energy-efficient, compact, and scalable photonic data center network. To support dynamic data center workloads efficiently, it is critical to switch between wavelengths in sub nanoseconds (ns). Here we demonstrate ultrafast photonic circuit switching based on a microcomb. Using a photonic integrated Si3N4 microcomb in conjunction with semiconductor optical amplifiers (SOAs), sub ns (< 500 ps) switching of more than 20 carriers is achieved. Moreover, the 25-Gbps non-return to zero (NRZ) and 50-Gbps four-level pulse amplitude modulation (PAM-4) burst mode transmission systems are shown. Further, on-chip Indium phosphide (InP) based SOAs and arrayed waveguide grating (AWG) are used to show sub-ns switching along with 25-Gbps NRZ burst mode transmission providing a path toward a more scalable and energy-efficient wavelength-switched network for future data centers.Comment: 11 pages, 6 figure

A survey for variable young stars with small telescopes: VI — Analysis of the outbursting Be stars NSW284, Gaia19eyy, and VES263

This paper is one in a series reporting results from small telescope observations of variable young stars. Here, we study the repeating outbursts of three likely Be stars based on long-term optical, near-infrared, and mid-infrared photometry for all three objects, along with follow-up spectra for two of the three. The sources are characterised as rare, truly regularly outbursting Be stars. We interpret the photometric data within a framework for modelling light curve morphology, and find that the models correctly predict the burst shapes, including their larger amplitudes and later peaks towards longer wavelengths. We are thus able to infer the start and end times of mass loading into the circumstellar disks of these stars. The disk sizes are typically 3 – 6 times the areas of the central star. The disk temperatures are ∼ 40 %, and the disk luminosities are ∼ 10 % of those of the central Be star, respectively. The available spectroscopy is consistent with inside-out evolution of the disk. Higher excitation lines have larger velocity widths in their double-horned shaped emission profiles. Our observations and analysis support the decretion disk model for outbursting Be stars

Analysis of Wear Resistance of Borided Steel C45

The wear resistance of diffusion coatings in conditions of specific pressures of 3, 7 and 10 MPa was studied. The boride coatings were prepared by means of diffusion methods using C45 steel as the substrate material. Research on the microstructure and redistribution of chemical elements on wear surface of a borided layer was carried out. It was found that the boride coatings should be used under a specific pressure of 7 MPa. It was found that the wear of friction couple coating of steel C45 under specific pressure of 3 MPa proceeds according to the oxidation wear mechanism, while under specific pressures of 7 and 10 MPa the abrasive wear prevails. The wear-induced segregation of atoms in coatings was studied using secondary mass-spectroscopy method (SIMS). Increased C, O, and B concentrations were noticed at the wear surface on depth from 50 to 2000 &Aring;. The secondary wear-induced structure formation on the wear surface resulted in high wear resistance of diffusion borided coatings

Numerical simulation methodologies for design and development of Diffuser-Augmented Wind Turbines – analysis and comparison

Different numerical computation methods used to develop a methodology for fast, efficient, reliable design and comparison of Diffuser-Augmented Wind Turbine (DAWT) geometries are presented. The demand for such methods is evident, following the multitude of geometrical parameters that influence the flow character through ducted turbines. The results of the Actuator Disk Model (ADM) simulations will be confronted with a simulation method of higher order of accuracy, i.e. the 3D Fully-resolved Rotor Model (FRM) in the rotor design point. Both will be checked for consistency with the experimental results measured in the wind tunnel at the Institute of Turbo-machinery (IMP), Lodz University of Technology (TUL). An attempt to find an efficient method (with a compromise between accuracy and design time) for the flow analysis pertinent to the DAWT is a novel approach presented in this paper

Multielemental Analysis of Various Kinds of Whisky

Whisky (whiskey) consists of many trace elements coming from the raw materials used in its fermentation, distillation and maturation processes. These ingredients assure the exceptional organoleptic characteristics of the beverage. Their analysis is important to better control the stages of fermentation, distillation, taste repeatability and for product quality assurance as well as from the brand protection point of view. This article presents the usefulness of modern analytical techniques based on elemental analysis. ICP mass spectrometry and CV atomic absorption spectroscopy were applied to distinguish whisky produced in Scotland from whisky coming from Ireland and the United States. The collected semi-quantitative data were used for multivariate analysis performed using the Statistica 10.0 software. The results showed that Irish whiskey is characterized by quite a high amount of Ba and Ti compared with other samples, which made it possible to distinguish this sample from the others. No strict correlation was found between the type of whisky and the amount of trace elements, however, the projection of objects on the first two components revealed that single malt samples created one cluster