Miracle-dz/UniFAR-FTUs huggingface dataset:
Non-Engine Order Blade Vibration in a High Pressure Compressor

High amplitude levels of blade vibration have occurred on the first rotor of a multi stage high pressure compressor. The frequencies are not in resonance with harmonics of the rotor speed. The excitation is aerodynamically caused and associated with a rotating flow instability in the blade tip region of the first compressor stage. A vortex shedding mechanism can be interpreted as a rotating source to generate pressure waves. The source moves relative to the blade row at a fraction of the rotor speed, similar to the 'well known mechanism' of rotating stall. To investigate the unsteady flow field in the tip region of the rotor and its relation to the blade vibration, measurements of the pressure and velocity fluctuations in the vicinity of the blade tips are compared with blade vibrations. A calculation model of the spectral characteristics of the pressure fluctuations confirms the measured data. The effect is sensitive to aerodynamic blade loading so that a modification in the design could reduce the mechanism of the rotating excitation.
Metalloproteins in the Biology of Heterocysts

Cyanobacteria are photoautotrophic microorganisms present in almost all ecologically niches on Earth. They exist as single-cell or filamentous forms and the latter often contain specialized cells for N2 fixation known as heterocysts. Heterocysts arise from photosynthetic active vegetative cells by multiple morphological and physiological rearrangements including the absence of O2 evolution and CO2 fixation. The key function of this cell type is carried out by the metalloprotein complex known as nitrogenase. Additionally, many other important processes in heterocysts also depend on metalloproteins. This leads to a high metal demand exceeding the one of other bacteria in content and concentration during heterocyst development and in mature heterocysts. This review provides an overview on the current knowledge of the transition metals and metalloproteins required by heterocysts in heterocyst-forming cyanobacteria. It discusses the molecular, physiological, and physicochemical properties of metalloproteins involved in N2 fixation, H2 metabolism, electron transport chains, oxidative stress management, storage, energy metabolism, and metabolic networks in the diazotrophic filament. This provides a detailed and comprehensive picture on the heterocyst demands for Fe, Cu, Mo, Ni, Mn, V, and Zn as cofactors for metalloproteins and highlights the importance of such metalloproteins for the biology of cyanobacterial heterocysts.
A Theoretical Approach for Passive Control of Thermoacoustic Oscillations: Application to Ducted Flames

In this paper, we develop a linear technique that predicts how the stability of a thermoacoustic system changes due to the action of a generic passive feedback device or a generic change in the base state. From this, one can calculate the passive device or base state change that most stabilizes the system. This theoretical framework, based on adjoint equations, is applied to two types of Rijke tube. The first contains an electrically heated hot wire, and the second contains a diffusion flame. Both heat sources are assumed to be compact, so that the acoustic and heat release models can be decoupled. We find that the most effective passive control device is an adiabatic mesh placed at the downstream end of the Rijke tube. We also investigate the effects of a second hot wire and a local variation of the cross-sectional area but find that both affect the frequency more than the growth rate. This application of adjoint sensitivity analysis opens up new possibilities for the passive control of thermoacoustic oscillations. For example, the influence of base state changes can be combined with other constraints, such as that the total heat release rate remains constant, in order to show how an unstable thermoacoustic system should be changed in order to make it stable. [DOI: 10.1115/1.4024957]
Patterns of Diversity of Floral Symmetry in Angiosperms: A Case Study of the Order Apiales

Floral symmetry is widely known as one of the most important structural traits of reproductive organs in angiosperms. It is tightly related to the shape and arrangement of floral parts, and at the same time, it plays a key role in general appearance (visual gestalt) of a flower, which is especially important for the interactions of zoophilous flowers with their pollinators. The traditional classification of floral symmetry divides nearly all the diversity of angiosperm flowers into actinomorphic and zygomorphic ones. Within this system, which is useful for ecological studies, many variations of symmetry appear to be disregarded. At the same time, the diversity of floral symmetry is underpinned not only by ecological factors, but also by morphogenetic mechanisms and constraints. Sometimes it is not an easy task to uncover the adaptive or developmental significance of a change of the floral symmetry in a particular lineage. Using the asterid order Apiales as a model group, we demonstrate that such changes can correlate with the merism of the entire flower or of its particular whorl, with the relative orientation of gynoecium to the rest of the flower, with the presence of sterile floral elements and other morphological characters. Besides, in some taxa, the shape and symmetry of the flower change in the course of its development, which should be taken in consideration in morphological comparisons and evaluations of synapomorphies in a particular clade. Finally, we show that different results can be obtained due to employment of different approaches: for instance, many flowers that are traditionally described as actinomorphic turn out to be disymmetric, monosymmetric, or asymmetric from a more detailed look. The traditional method of division into actinomorphy and zygomorphy deals with the general appearance of a flower, and mainly considers the shape of the corolla, while the geometrical approach handles the entire three-dimensional structure of the flower, and provides an exact number of its symmetry planes.
The Determinants of Sovereign Risk Premium in African Countries

This paper investigates the determinants of the sovereign risk premium in African countries. We employ the dynamic fixed effects model to determine the key drivers of sovereign bond spreads. Country-specific effects are fixed and the inclusion of dummy variables using the Bai–Perron multiple structural break test is significant at a 5% level. For robustness, the time-series generalized method of moments (GMM) is used where the null hypothesis of the Sargan Test of over-identifying restrictions (OIR) and the Arellano–Bond Test of no autocorrelation are not rejected. This implies that the instruments used are valid and relevant. In addition, there is no autocorrelation in the error terms. Our results show that the exchange rate, Money supply/GDP (M2/GDP) ratio, and trade are insignificant. Furthermore, our findings indicate that public debt/GDP ratio, GDP growth, inflation rate, foreign exchange reserves, commodity price, and market sentiment are significant at a 5% and 10% level.
Computational study of ignition behavior and hotspot dynamics of a potential class of aluminized explosives

The ignition behavior and hotspot dynamics of a potential class of aluminized energetic materials are studied computationally. The materials consist of HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) grains embedded in an aluminum matrix and, henceforth referred to as metal–matrix explosives (MMXs). For the analysis, two different MMXs, the soft MMX with a matrix of 1100 Al alloy and the hard MMX with a matrix of 7075 T651 Al alloy are considered. The thermo-mechanical response of the MMXs are computationally analyzed by subjecting them to monotonic impact loading using a Lagrangian cohesive finite element framework, with their ignition behavior analyzed through characterization of hotspots. For comparison, a polymer-bonded explosive (PBX) consisting of HMX and Estane is also analyzed under the same conditions. The results show that the MMXs have significantly lower propensity for ignition and higher structural integrity than the PBX over the loading velocity range of 200–500 m s−1.
DETERMINATION OF FIBRE SATURATION POINT OF SELECTED TROPICAL WOOD SPECIES USING DIFFERENT METHODS

The main objective of this research was to determine the fibre saturation point of tropical wood. Two different methods were used to achieve this aim: the logarithm of strength properties versus moisture content and volumetric shrinkage-moisture content plot to zero shrinkage. The test included selected wood species from Africa: Opepe, Iroko, African padouk, and Wenge, and South America: American mahogony and Ipe. For comparison, selected domestic wood species of a similar structure – European beech (Fagus sylvatica L.) – were also tested. Determination of the fibre saturation point of the selected wood species using two methods delivered similar results (the small differences were not significant). The results showed that, generally, the fibre saturation point of the tropical wood species was lower than in the case of the European wood species. The lowest values of the fibre saturation point were shown by the African padouk and Ipe (approx. 17 %). Moreover, it was found that in the case of the tropical wood, the basic density had a significant influence on the sorption properties of the tested wood species.
Performance Assessment of MOD16 in Evapotranspiration Evaluation in Northwestern Mexico

Evapotranspiration (ET) is the second largest component of the water cycle in arid and semiarid environments, and, in fact, more than 60% of the precipitation on earth is returned to the atmosphere through it. MOD16 represents an operational source of ET estimates with adequate spatial resolution for several applications, such as water resources planning, at a regional scale. However, the use of these estimates in routine applications will require MOD16 evaluation and validation using accurate ground-based measurements. The main objective of this study was to evaluate the performance of the MOD16A2 product by comparing it with eddy covariance (EC) systems. Additional objectives were the analysis of the limitations, uncertainties, and possible improvements of the MOD16-estimated ET. The EC measurements were acquired for five sites and for a variety of land covers in northwestern Mexico. The indicators used for the comparison were: root mean square error (RMSE), bias (BIAS), concordance index (d), and determination coefficient (R2) of the correlation, comparing measured and modelled ET. The best performance was observed in Rayon (RMSE = 0.77 mm∙day−1, BIAS = −0.46 mm∙day−1, d = 0.88, and R2 = 0.86); El Mogor and La Paz showed errors and coefficients of determination comparable to each other (RMSE = 0.39 mm·day−1, BIAS = −0.04 mm∙day−1, R2 = 0.46 and RMSE = 0.42 mm·day−1, BIAS = −0.18 mm∙day−1, R2 = 0.45, respectively). In most cases, MOD16 underestimated the ET values.
Fractional quantum Hall effect in the interacting Hofstadter model via tensor networks

We show via tensor network methods that the Harper-Hofstadter Hamiltonian for hard-core bosons on a square geometry supports a topological phase realizing the $\ensuremath{\nu}=\frac{1}{2}$ fractional quantum Hall (FQH) effect on the lattice. We address the robustness of the ground-state degeneracy and of the energy gap, measure the many-body Chern number, and characterize the system using Green functions, showing that they decay algebraically at the edges of open geometries, indicating the presence of gapless edge modes. Moreover, we estimate the topological entanglement entropy by taking a combination of lattice bipartitions that reproduces the topological structure of the original proposals by Kitaev and Preskill [Phys. Rev. Lett. 96, 110404 (2006)] and Levin and Wen [Phys. Rev. Lett. 96, 110405 (2006)]. The numerical results show that the topological contribution is compatible with the expected value $\ensuremath{\gamma}=\frac{1}{2}$. Our results provide extensive evidence that FQH states are within reach of state-of-the-art cold-atom experiments.
Synergy processing of diverse ground-based remote sensing and in situ data using the GRASP algorithm: applications to radiometer, lidar and radiosonde observations

Abstract. The exploration of aerosol retrieval synergies from diverse combinations of ground-based passive Sun-photometric measurements with collocated active lidar ground-based and radiosonde observations using versatile Generalized Retrieval of Atmosphere and Surface Properties (GRASP) algorithm is presented. Several potentially fruitful aspects of observation synergy were considered. First, a set of passive and active ground-based observations collected during both day- and nighttime was inverted simultaneously under the assumption of temporal continuity of aerosol properties. Such an approach explores the complementarity of the information in different observations and results in a robust and consistent processing of all observations. For example, the interpretation of the nighttime active observations usually suffers from the lack of information about aerosol particles sizes, shapes and complex refractive index. In the realized synergy retrievals, the information propagating from the nearby Sun-photometric observations provides sufficient constraints for reliable interpretation of both day- and nighttime lidar observations. Second, the synergetic processing of such complementary observations with enhanced information content allows for optimizing the aerosol model used in the retrieval. Specifically, the external mixture of several aerosol components with predetermined sizes, shapes and composition has been identified as an efficient approach for achieving reliable retrieval of aerosol properties in several situations. This approach allows for achieving consistent and accurate aerosol retrievals from processing stand-alone advanced lidar observations with reduced information content about aerosol columnar properties. Third, the potential of synergy processing of the ground-based Sun-photometric and lidar observations, with the in situ backscatter sonde measurements was explored using the data from KAUST.15 and KAUST.16 field campaigns held at King Abdullah University of Science and Technology (KAUST) in the August of 2015 and 2016. The inclusion of radiosonde data has been demonstrated to provide significant additional constraints to validate and improve the accuracy and scope of aerosol profiling. The results of all retrieval setups used for processing both synergy and stand-alone observation data sets are discussed and intercompared.
How Basic Behavior of LENR can Guide A Search for an Explanation

The LENR effect was identified 27 years ago by Profs. Fleischmann and Pons as production of extra energy in a normal chemical structure, in this case PdD. Over a thousand published papers now support the discovery and the energy is shown to result from fusion of hydrogen isotopes without the need to apply energy and without energetic radiation being produced. By conventional standards, the claims are impossible. Nevertheless, a new phenomenon has been discovered requiring acceptance and understanding. The major behaviors and their present understanding are described in this paper and are used to suggest how an effective explanation might be constructed. Once again, science has been forced to either reject the obvious or accept the impossible. In this case, the normal skepticism needs to be ignored in order to determine if this promised energy source is real and can provide the ideal energy so critically needed. c © 2016 ISCMNS. All rights reserved. ISSN 2227-3123
Can black carbon in snow be detected by remote sensing?

In remote areas of the Northern Hemisphere, typical mixing ratios of black carbon (BC) in snow are 3–30 ng/g. In cold fine‐grained snow these BC amounts can reduce the broadband albedo by 0–1% and the visible‐wavelength albedo by 0–2%, representing significant climatic forcings. In melting snow the reductions are larger, 0–3% and 1–6%, respectively. Surface albedos inferred from satellite measurements have typical errors of a few percent, so a signal of reduced albedo will be difficult to detect. The inference of albedo from a nadir radiance measurement can be biased low because of undetected thin clouds or blowing snow altering the angular reflectance pattern. But even if the albedo could be measured perfectly from satellite, its attribution would be ambiguous because of the vertical variation of snow grain size, absorbing aerosol in the atmosphere above the snow, and especially because of subpixel heterogeneity of the thin and patchy snow cover of the Arctic and many other treeless regions. The spectral signature of thin snow resembles that of BC in snow. For these reasons, attempts to use satellite remote sensing to estimate the BC content of snow, or the reduction of albedo by BC, are unlikely to be successful, except in highly polluted industrial regions.
Classification Method to Define Synchronization Capability Limits of Line-Start Permanent-Magnet Motor Using Mesh-Based Magnetic Equivalent Circuit Computation Results

Line start permanent magnet synchronous motors (LS-PMSM) are energy-efficient synchronous motors that can start asynchronously due to a squirrel cage in the rotor. The drawback, however, with this motor type is the chance of failure to synchronize after start-up. To identify the problem, and the stable operation limits, the synchronization at various parameter combinations is investigated. For accurate knowledge of the operation limits to assure synchronization with the utility grid, an accurate classification of parameter combinations is needed. As for this, many simulations have to be executed, a rapid evaluation method is indispensable. To simulate the dynamic behavior in the time domain, several modeling methods exist. In this paper, a discussion is held with respect to different modeling methods. In order to include spatial factors and magnetic nonlinearities, on the one hand, and to restrict the computation time on the other hand, a magnetic equivalent circuit (MEC) modeling method is developed. In order to accelerate numerical convergence, a mesh-based analysis method is applied. The novelty in this paper is the implementation of support vector machine (SVM) to classify the results of simulations at various parameter combinations into successful or unsuccessful synchronization, in order to define the synchronization capability limits. It is explained how these techniques can benefit the simulation time and the evaluation process. The results of the MEC modeling correspond to those obtained with finite element analysis (FEA), despite the reduced computation time. In addition, simulation results obtained with MEC modeling are experimentally validated.
Torque Mapping Lower Level ControlTrunk Control Gravity Compensation Momentum Based Observer + QP Optimization Planner User Input Foot Scheduler Whole-Body Controller Terrain Estimation State Estimation

We present a passivity-based Whole-Body Control approach for quadruped robots that achieves dynamic locomotion while compliantly balancing the robot’s trunk. We formulate the motion tracking as a Quadratic Program (QP) that takes into account the full robot rigid body dynamics, the actuation limit, the joint limits and the contact interaction. We analyze the controller robustness against inaccurate friction coefficient estimates and unstable footholds, as well as its capability to redistribute the load as a consequence of enforcing actuation limits. Additionally, we present some practical implementation details gained from the experience with the real platform. Extensive experimental trials on the 90 Kg Hydraulically actuated Quadruped (HyQ) robot validate the capabilities of this controller under various terrain conditions and gaits. The proposed approach is expedient for accurate execution of high dynamic motions with respect to the current state of the art.
Chemical Composition and Toxicity of Particles Emitted from a Consumer-level 3D Printer using Various Materials.

Consumer-level 3D printers emit ultrafine and fine particles, though little is known about their chemical composition or potential toxicity. We report on chemical characteristics of the particles in comparison to raw filaments, and assessments of particle toxicity. Particles emitted from polylactic acid (PLA) appeared to be largely composed of the bulk filament material with mass spectra similar to the PLA monomer spectra. Acrylonitrile butadiene styrene (ABS), extruded at a higher temperature than PLA, emitted vastly more particles and their composition differed from that of the bulk filament, suggesting that trace additives may control particle formation. In vitro cellular assays and in vivo mice exposure all showed toxic responses when exposed to PLA and ABS-emitted particles, where PLA-emitted particles elicited higher response levels than ABS-emitted particles at comparable mass doses. A chemical assay widely used in ambient air-quality studies showed particles from various filament materials had comparable particle oxidative potentials, slightly lower than those of ambient particulate matter (PM2.5). However, particle emissions from ABS filaments are likely more detrimental when considering overall exposure due to much higher emissions. Our results suggest that 3D printer particle emissions are not benign and exposures should be minimized.
Spread of correlations in long-range interacting systems

Understanding the dynamics of many-body systems is crucial for understanding, e.g., thermalization or transmission of information. Nevertheless, little is known in the case of quantum systems with long-range interactions. Here, we analyze the long-range Ising model in a transverse field, where interactions decay as a power-law with distance $\propto r^{-\alpha}$, $\alpha>0$. Using complementary numerical and analytical techniques, we identify three dynamical regimes: short-range-like with an emerging light cone for $\alpha>2$; weakly long-range for $1<\alpha<2$ without a clear light cone but with a finite propagation speed of excitations; and fully non-local for $\alpha<1$ with instantaneous transmission of correlations. This last regime breaks generalized Lieb--Robinson bounds. Numerical calculation of the entanglement spectrum demonstrates that the usual picture of propagating quasi-particles remains valid for long-range interactions. This allows an intuitive interpretation in terms of qualitative changes to the spin-wave dispersion, leading to diverging quasi-particle velocities in the long-range regime. Our results may be tested in state-of-the-art trapped-ion experiments.
Spin-Orbit Coupling Parameters of sp2 Nanocarbons

The paper presents a new approach to the determination of standard spin-orbit coupling parameters, such as the SOC constant a_SO and the Lande parameter g, by using peculiarities of UHF results for open-shell systems. The approach is convincingly approved for stretched ethylene and fullerene C60 as examples, thus justifying at once a high efficacy of the UHF formalism to disclose SOC features.