Miracle-dz/UniFAR-FTUs huggingface dataset:
Power System Small-Signal Angular Stability Affected by Virtual Synchronous Generators

This paper examines the small-signal angular stability of a power system affected by a virtual synchronous generator (VSG). The examination is based on an interconnected model with two subsystems. The VSG under the examination is modeled as the VSG subsystem. The rest of power system (ROPS) forms the other subsystem. Damping torque analysis is applied to indicate that when an oscillation mode of the VSG subsystem is in the proximity of an electromechanical oscillation mode of the ROPS subsystem on the complex plane, strong dynamic interactions are introduced by the VSG to decrease the small-signal angular stability of the power system. This implies that when the parameters of the VSG are set, modal proximity of the VSG to the electromechanical oscillation mode of the ROPS subsystem should be examined to avoid the detrimental impact of the VSG on power system small-signal angular stability. A method to evade the modal proximity is proposed in this paper for guiding the design of the VSG. Two example power systems with multiple VSGs for the wind power generation and transmission are presented. Study cases demonstrate and evaluate the analysis about the impact of modal proximity and proposed method for guiding the parameters setting of VSGs.
Complete and phase synchronization in a heterogeneous small-world neuronal network

Synchronous firing of neurons is thought to be important for information communication in neuronal networks. This paper investigates the complete and phase synchronization in a heterogeneous small-world chaotic Hindmarsh–Rose neuronal network. The effects of various network parameters on synchronization behaviour are discussed with some biological explanations. Complete synchronization of small-world neuronal networks is studied theoretically by the master stability function method. It is shown that the coupling strength necessary for complete or phase synchronization decreases with the neuron number, the node degree and the connection density are increased. The effect of heterogeneity of neuronal networks is also considered and it is found that the network heterogeneity has an adverse effect on synchrony.
Multifunction Lidar System Based on Polarization-Division Multiplexing

A multifunction lidar system is proposed based on polarization-division multiplexing, by which the distance, velocity, and depolarization ratio of a target can be simultaneously measured. The key component of the lidar system is a polarization-division multiplexing dual-drive Mach-Zehnder modulator (PDM-DMZM). A linear frequency-modulated (LFM) waveform is applied to one sub-DMZM of the PDM-DMZM to modulate the light along one polarization direction, while a single-frequency RF signal is applied to the other sub-DMZM to modulate the light along the orthogonal polarization direction. As a result, a dual-polarization light beam containing both the LFM and single-frequency optical signals is generated. In the receiver, a polarization beam splitter is used to separate the two orthogonally-polarized optical signals of the reflected light, so that the distance and velocity can be separately measured in two channels. Meanwhile, the depolarization ratio of the reflected light can be measured according to the intensity ratio between the LFM and single-frequency RF signals. An experiment was carried out to test this lidar system, in which an 8–18 GHz saw-tooth LFM signal and a 10 GHz single-frequency signal were, respectively, used to modulate the orthogonally-polarized lights. The distance and velocity were simultaneously measured with resolutions of 1.8 cm and 1.1 mm/s, respectively. In addition, the depolarization ratio of the reflected light was measured simultaneously.
Aspect Ratio Independent Etching: Fact or Fantasy?

The scaling of anisotropic plasma etch rates with feature dimensions is an important issue when fabricating microelectronic and photonic devices. For a wide rage of conditions, etch rates are found to scale primarily with the feature depth/width or aspect ratio. Features with large aspect ratios etch more slowly than those with low aspect ratios regardless of feature width. However, in the presence of etch inhibitors, the scaling of etching rates with feature dimensions becomes more complicated. Smaller aspect ratio features may etch more slowly than larger aspect ratio features suggesting that etch-inhibiting chemistry could be exploited in achieving the here-to-fore elusive goal of aspect ratio independent etching (ARIE). Using a well-established etching model, based on Langmuir adsorption kinetics, we derive the etch inhibitor flux and surface adsorption parameters required to achieve ARIE. Although the required parameters are non-physical when the range of aspect ratios is unconstrained, it is possible to achieve ARIE over a restricted range of aspect ratios. However, the balance required between ion, etchant, and inhibitor fluxes is a fragile one. The best approach to minimizing the variation in etching rate with aspect ratio is to operate a high density plasma at low pressure with high neutral flow rates.
Insect hydrocarbons : biology, biochemistry, and chemical ecology

Part 1. Chemistry, Biochemistry and Physiology: 1. Introduction: History and overview of insect hydrocarbons Gary J. Blomquist and Anne-Genevieve Bagneres 2. Structure and analysis of insect hydrocarbons Gary J. Blomquist 3. Biosynthesis of cuticular hydrocarbon Gary J. Blomquist 4. Molecular biology and genetics of hydrocarbon production Claude Wicker-Thomas and Thomas Chertemps 5. Site of synthesis, mechanism of transport and selective deposition of hydrocarbons Anne-Genevieve Bagneres and Gary J. Blomquist 6. Cuticular and water balance Allen Gibbs and Subhash Rajpurohit 7. Chemical taxonomy with hydrocarbons Anne-Genevieve Bagneres and Claude Wicker-Thomas 8. Chemical synthesis of insect cuticular hydrocarbons Jocelyn Millar 9. Oxygenated derivatives of hydrocarbons James S. Buckner Part II. Chemical Communication: 10. Perception and olfaction of cuticular compounds Mamiko Ozaki and Ayako Wada-Katsumata 11. Nestmate recognition in social insects and the role of hydrocarbons. Jelle S. van Zweden and Patrizia d'Ettorre 12. Cuticular hydrocarbon cues in the formation and maintenance of insect social groups Michael Green 13. Hydrocarbon profiles indicate fertility and dominance status in ant, bee, and wasp colonies Juergen Liebig 14. Chemical deception/mimicry using cuticular hydrocarbons Anne-Genevieve Bagneres and Cristina Lorenzi 15. Behavioral and evolutionary roles of cuticular hydrocarbons in Diptera Jean-Francois Ferveur and Matthew Cobb 16. Contact recognition pheromones in scorpions and spiders Marie Trabalon and Anne-Genevieve Bagneres 17. Hydrocarbons as contact pheromones of longhorned beetles Matthew D. Ginzel 18. Polyene hydrocarbons, epoxides, and related compounds as components of lepidopteran pheromone blends Jocelyn Millar 19. Volatile hydrocarbon pheromones from beetles Robert Bartelt 20. New areas of research on insect hydrocarbons and conclusion Abraham Hefetz, Claude Wicker-Thomas and Anne-Genevieve Bagneres.
Topological horseshoe analysis and field-programmable gate array implementation of a fractional-order four-wing chaotic attractor

We present a fractional-order three-dimensional chaotic system, which can generate four-wing chaotic attractor. Dynamics of the fractional-order system is investigated by numerical simulations. To rigorously verify the chaos properties of this system, the existence of horseshoe in the four-wing attractor is presented. Firstly, a Poincaré section is selected properly, and a first-return Poincaré map is established. Then, a one-dimensional tensile horseshoe is discovered, which verifies the chaos existence of the system in mathematical view. Finally, the fractional-order chaotic attractor is implemented physically with a field-programmable gate array (FPGA) chip, which is useful in further engineering applications of information encryption and secure communications.
Principal waves in multiply connected waveguides: concentration of laser radiation on areas of subwavelength dimensions

It is demonstrated that multiply connected waveguides can be used for the localisation or concentration of electromagnetic radiation at optical frequencies on areas of subwavelength transverse dimensions. In optical microscopes this makes subwavelength resolution possible along all three spatial coordinates. The use of multiply connected waveguides of subwavelength dimensions in the interaction of matter with laser radiation can increase considerably the field intensity in an optical wave. Applications of subwavelength waveguides in submicron photolithography, nanotechnology for microelectronics, and optical data storage and retrieval are discussed.
Nanostructured probes for scanning near-field optical microscopy

A novel concept for the fabrication of nanostructured probe tips for application in scanning near-field optical microscopy (SNOM) based on micromachining and thin-film technology is presented. This concept allows for the reproducible batch fabrication of aperture probe tips consisting of a transparent silicon nitride cone with a sharp tip apex surrounded by a metallic coating. Furthermore, the concept can be extended to the fabrication of probe tips with a coaxial nanostructure or a single nanoelectrode. The tip fabrication can be integrated into micromachining processes for the batch fabrication of scanning probe microscopy sensors and therefore leads to new types of multifunctional probes. Here the integration of the SNOM probe tip into an AFM cantilever equipped with an integrated optical waveguide designed for simultaneous AFM/SNOM operation is described.
Evolution of the phase-space density and the Jeans scale for dark matter derived from the Vlasov-Einstein equation

We discuss solutions of Vlasov-Einstein equation for collisionless dark matter particles in the context of a flat Friedmann universe. We show that, after decoupling from the primordial plasma, the dark matter phase-space density indicator Q = ρ/(σ1D2)3/2 remains constant during the expansion of the universe, prior to structure formation. This well known result is valid for non-relativistic particles and is not ``observer dependent'' as in solutions derived from the Vlasov-Poisson system. In the linear regime, the inclusion of velocity dispersion effects permits to define a physical Jeans length for collisionless matter as function of the primordial phase-space density indicator: λJ = (5π/G)1/2Q−1/3ρdm−1/6. The comoving Jeans wavenumber at matter-radiation equality is smaller by a factor of 2-3 than the comoving wavenumber due to free-streaming, contributing to the cut-off of the density fluctuation power spectrum at the lowest scales. We discuss the physical differences between these two scales. For dark matter particles of mass equal to 200 GeV, the derived Jeans mass is 4.3 × 10−6M⊙.
Supernova mechanisms. [SN 1987a]

Supernovae of Type II occur at the end of the evolution of massive stars. The phenomenon begins when the iron core of the star exceeds a Chandrasekhar mass. The collapse of that core under gravity is well understood and takes a fraction of a second. To understand the phenomenon, a detailed knowledge of the equation of state at the relevant densities and temperatures is required. After collapse, the shock wave moves outward, but probably does not succeed in expelling the mass of the star. The most likely mechanism to do so is the absorption of neutrinos from the core by the material at medium distances. Observations and theory connected with SN 1987A are discussed, as are the conditions just before collapse and the emission of neutrinos by the collapsed core.
University of Birmingham Effect of surface characteristics on cleaning performance for CIP system in food processing

District heating networks are commonly addressed in the literature as one of the most effective solutions for decreasing the greenhouse gas emissions from the building sector. These systems require high investments which are returned through the heat sales. Due to the changed climate conditions and building renovation policies, heat demand in the future could decrease, prolonging the investment return period. The main scope of this paper is to assess the feasibility of using the heat demand – outdoor temperature function for heat demand forecast. The district of Alvalade, located in Lisbon (Portugal), was used as a case study. The district is consisted of 665 buildings that vary in both construction period and typology. Three weather scenarios (low, medium, high) and three district renovation scenarios were developed (shallow, intermediate, deep). To estimate the error, obtained heat demand values were compared with results from a dynamic heat demand model, previously developed and validated by the authors. The results showed that when only weather change is considered, the margin of error could be acceptable for some applications (the error in annual demand was lower than 20% for all weather scenarios considered). However, after introducing renovation scenarios, the error value increased up to 59.5% (depending on the weather and renovation scenarios combination considered). The value of slope coefficient increased on average within the range of 3.8% up to 8% per decade, that corresponds to the decrease in the number of heating hours of 22-139h during the heating season (depending on the combination of weather and renovation scenarios considered). On the other hand, function intercept increased for 7.8-12.7% per decade (depending on the coupled scenarios). The values suggested could be used to modify the function parameters for the scenarios considered, and improve the accuracy of heat demand estimations. © 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the Scientific Committee of The 15th International Symposium on District Heating and Cooling.
Dark matter direct detection with non-Maxwellian velocity structure

The velocity distribution function of dark matter particles is expected to show significant departures from a Maxwell-Boltzmann distribution. This can have profound effects on the predicted dark matter - nucleon scattering rates in direct detection experiments, especially for dark matter models in which the scattering is sensitive to the high velocity tail of the distribution, such as inelastic dark matter (iDM) or light (few GeV) dark matter (LDM), and for experiments that require high energy recoil events, such as many directionally sensitive experiments. Here we determine the velocity distribution functions from two of the highest resolution numerical simulations of Galactic dark matter structure (Via Lactea II and GHALO), and study the effects for these scenarios. For directional detection, we find that the observed departures from Maxwell-Boltzmann increase the contrast of the signal and change the typical direction of incoming DM particles. For iDM, the expected signals at direct detection experiments are changed dramatically: the annual modulation can be enhanced by more than a factor two, and the relative rates of DAMA compared to CDMS can change by an order of magnitude, while those compared to CRESST can change by a factor of two. The spectrum of the signal can also change dramatically, with many features arising due to substructure. For LDM the spectral effects are smaller, but changes do arise that improve the compatibility with existing experiments. We find that the phase of the modulation can depend upon energy, which would help discriminate against background should it be found.
Gravitational waves from the electroweak phase transition

We study the generation of gravitational waves in the electroweak phase transition. We consider a few extensions of the Standard Model, namely, the addition of scalar singlets, the minimal supersymmetric extension, and the addition of TeV fermions. For each model we consider the complete dynamics of the phase transition. In particular, we estimate the friction force acting on bubble walls, and we take into account the fact that they can propagate either as detonations or as deflagrations preceded by shock fronts, or they can run away. We compute the peak frequency and peak intensity of the gravitational radiation generated by bubble collisions and turbulence. We discuss the detectability by proposed spaceborne detectors. For the models we considered, runaway walls require significant fine tuning of the parameters, and the gravitational wave signal from bubble collisions is generally much weaker than that from turbulence. Although the predicted signal is in most cases rather low for the sensitivity of LISA, models with strongly coupled extra scalars reach this sensitivity for frequencies f ∼ 10−4 Hz, and give intensities as high as h2ΩGW ∼ 10−8.
Modular multilevel converters technology: a comprehensive study on its topologies, modelling, control and applications

A modular multilevel converter (MMC) is one of the perfect topologies for high power and medium-/high-voltage energy conversion systems. The MMC has attractive features such as modularity, voltage and current scalability, transformerless operation, fault blocking capability, reduced filter size, a reduced ripple of the output current, high efficiency, and low expense on redundancy. These features attracted industries over the past few years, notable research has been carried out on MMC topologies, their operation, and control. This study presents a review of MMC topologies and their mathematical models. Furthermore, their control schemes (classical as well as model predictive controls) and modulation techniques are discussed. Finally, MMC applications and their future challenges are highlighted.
Estimation of Water Needs of Sweet Potato (Ipomea batata) Using the Penman-Monteith Model in Abeokuta, South-western Nigeria

Adequate knowledge of crop water needs is required for effective water management and application in Abeokuta, a typical sub humid part of southwestern Nigeria. This research was carried out to determine the crop water requirements, rainfall intensity and irrigation water requirements of sweet potato for agricultural activities in Abeokuta. The estimation of water needs of sweet potato was based on twenty-one years meteorological data. The meteorological data collected were used for the estimation of reference evapotranspiration (ETo) using Penman â€“ Monteith model. The results obtained showed that the Monthly reference evapotranspiration (ETo) varied from 96.90 to 165.23 mm/month with a mean of 131.58 mm/month. The seasonal crop evapotranspiration (ETc) values for early and late season sweet potato are 338.37 mm and 468.03 mm respectively. The rainfall intensity of the study area varied from 0.20 â€“ 8.56 mm/hr with mean of 4.22 mm/hr. The study showed that the study area has low rainfall intensity values. However, this will promote steady infiltration of rainwater into the soil hereby giving the soil adequate moisture content needed by the crop to attain its optimum growth yield. The Irrigation water requirement was 22.80 mm and 473.87 mm for early and late season respectively. To achieve optimum crop performance and production of quality yield sweet potato in Abeokuta, supplementary irrigation is necessary during the early and late growing seasons of the crop.
Spherical collapse in chameleon models

We study the gravitational collapse of an overdensity of nonrelativistic matter under the action of gravity and a chameleon scalar field. We show that the spherical collapse model is modified by the presence of a chameleon field. In particular, we find that even though the chameleon effects can be potentially large at small scales, for a large enough initial size of the inhomogeneity the collapsing region possesses a thin shell that shields the modification of gravity induced by the chameleon field, recovering the standard gravity results. We analyse the behaviour of a collapsing shell in a cosmological setting in the presence of a thin shell and find that, in contrast to the usual case, the critical density for collapse in principle depends on the initial comoving size of the inhomogeneity.
Effects of RR segment duration on HRV spectrum estimation

Although patterns of heart rate variability (HRV) hold considerable promise for clarifying issues in clinical applications, the inappropriate quantification and interpretation of these patterns may obscure critical issues or relationships and may impede rather than foster the development of clinical applications. The duration of the RR interval series is not a matter of convenience but a fine balance between two important issues: acceptable variance and stationarity of the time series on one hand, and acceptable resolution of the spectral estimate and reduced spectral leakage on the other. Further, in the standard short-term HRV analysis, it has been observed that the previous studies in HRV spectral analysis use a wide range of RR interval segment duration for spectral estimation by Welch's algorithm. The standardization of RR interval segment duration is also important for comparisons among studies and is essential for within-study experimental contrasts. In the present study, a comparative analysis for RR interval segment durations has been made to propose an optimal RR interval segment duration. Firstly a simulated signal was analyzed with Hann window and zero padding for the segment lengths of 1024, 512, 256 and 128 samples resampled at 4 Hz with 50% overlapping. Again, the above procedure was applied to RR interval series and it was concluded that segment length of 256 samples with 50% overlapping provides a smoothed spectral estimate with clearly outlined peaks in low- and high-frequency bands. This easily understandable and interpretable spectral estimate leads to a better visual and automated analysis, which is not only desirable in basic physiology studies, but also a prerequisite for a widespread utilization of frequency domain techniques in clinical studies, where simplicity and effectiveness of information are of primary importance.
Jak se počítají substantiva v češtině: poznámky ke kategorii čísla

The present contribution deals with the grammatical category of number in Czech nouns. On the basis of empirical investigation, we propose the introduction of a new semantic distinction within the forms of nouns, namely the distinction of a simple quantitative meaning versus a pair/group meaning. There are nouns in Czech that typically refer to a pair or to a (commonly encountered) group of entities, not merely to a large amount of these entities (e.g. ruce ‘arms’, vlasy ‘hair’, or sirky ‘matches’). These nouns are combined with set numerals rather than with the basic ones. In the paper, we argue that the above mentioned subcategorization is grammaticalized. A brief outline of the expressions of the pair/group meaning in Czech as compared to some other languages (German, English, Slavonic) is also provided.
DIGITAL SURVEYS AND 3D RECONSTRUCTIONS FOR AUGMENTED ACCESSIBILITY OF ARCHAEOLOGICAL HERITAGE

Abstract. This paper presents part of the results of a larger research project that focused on the surveying and documenting of Roman theatres and amphitheatres in the Campania region as well as the testing of a virtual fruition system for the digital reconstruction of a case study: the Roman theatre of Benevento. The work was carried out by the research group at the Interdepartmental Urban/Eco Research Centre of the University of Naples Federico II in collaboration with Spinvector, a company specialized in ICT – Information and Communication Technology – which lead to the defining of a fruition system of Cultural Heritage applied to archaeological heritage.The project included 3D digital surveys of the study samples carried out using reality-based techniques, which allowed for the acquisition of metric, morphological, geometric and colorimetric data. This made it possible to elaborate three-dimensional models, based on the current configuration of the places as well as of the possible original reconfigurations.