Miracle-dz/UniFAR-FTUs huggingface dataset:
Numerical Investigation of Edge Flame Propagation Behavior in an Igniting Turbulent Planar Jet

The effects of strain rate and curvature on the edge flame propagation characteristics in an igniting turbulent coflowing planar jet are studied based on 3-dimensional compressible Direct Numerical Simulation (DNS) with a modified single-step Arrhenius chemistry. In the present configuration the high-speed jet fluid is considered to be fuel-rich, whereas the slow-moving coflowing fluid is taken to be fuel-lean. Consistent with previous work with DNS without mean flow and shear, the resulting flame from localized forced ignition at the jet exhibits predominantly premixed edge flame structure where premixed flames are formed on both the fuel-rich and fuel-lean sides and the intersection between these two branches propagate on the stoichiometric mixture fraction isosurface. The edge flame propagation behavior has been studied in terms of the statistics of the edge flame displacement speed S d , which refers to the speed at which the fuel mass fraction Y F isosurface moves normal to itself, relative to an initially coincident material surface at the intersection between the fuel-rich and fuel-lean premixed flames on the stoichiometric mixture fraction isosurface. The probability density function of the density-weighted edge flame displacement speed shows nonzero probability of finding negative values of at later stages of self-sustained flame propagation. The mean value of decreases after the energy deposition is switched off but eventually settles to a value that does not change appreciably with time. The is found to be predominantly negatively correlated with curvature but the correlation between and tangential strain rate shows both positive and negative correlating trends with the positive correlating trend dominant at later stages of flame propagation. It has been found that strain rate and curvature dependences of |∇Y F | have significant influences on the statistical behavior of in response to strain rate and curvature. The observed strain rate and curvature dependences of have been explained in detail in terms of statistical behaviors of the reaction, normal diffusion, and the tangential diffusion components of (i.e., , , and ).
Electrochemical synthesis of heterocyclic compounds. XII. Anodic oxidation of catechol in the presence of nucleophiles

The electrochemical synthesis of coumestan derivatives and some related heterocyclic system (2a-11a) by anodic oxidation of catechol (1) in the presence of various nucleophiles 2-11 is described. Products were obtained in good yields and purity. The mechanism of oxidation was deduced from voltammetric data and by coulometry at controlled potential.
On the Linearizing Effect of Temporal Averaging in Nonlinear Dynamical Systems

Application of low pass filters (LPFs) to remove noise components is a widely used methodology for processing signals acquired from diverse systems. LPFs are also intrinsic components of many natural and man-made systems, both intended and epiphenomenal, from electromechanical systems to traffic networks and the brain. Across all cases, the effects of LPFs are often studied in a pure filtering sense, such as temporal smoothing and removing high-pass noise components, causing delays and phase distortions, or limiting bandwidths. In this work, we instead show that low-pass filtering and the temporal averaging that underlies it can also have a major and fundamental impact on the linearity of the dynamics. We show using rigorous analysis that across a wide range of stochastic nonlinear systems, temporal averaging dampens nonlinearities and leads to more and more linear dynamics with stronger temporal averaging (lower LPF cutoff frequency), leading asymptotically to a completely linear system as the width of the window over which temporal averaging occurs tends to infinity (LPF cutoff frequency tends to zero). Our results have major implications in a wide range of application areas, including the study of the nervous system whereby LPFs are biologically and algorithmically abundant and a growing body of empirical evidence has found linear models as capable as nonlinear ones in describing neuronal time series.
Self-trapping of the amide I band in a peptide model crystal

A femtosecond pump-probe study of the peculiar amide I band of acetanilide, a molecular crystal with hydrogen bonded chains of peptide units, is presented. The almost perfect harmonicity of the 1666 cm−1 subpeak is related to significant delocalization of this state at low enough temperatures (93 K). The “anomalous” peak (1650 cm−1), on the other hand, is strongly anharmonic, and hence assigned to a self-trapped state. This assignment is in agreement with a more indirect previous work. With increasing temperature, thermal disorder localizes the 1666 cm−1 band (Anderson localization) and at the same time destroys the self-trapping mechanism. Both the self-trapped state and the delocalized state decay on a 2 ps time scale into states outside the spectral window of this study. The excitation energy reappears on a much slower 35 ps time scale in the form of an increased lattice temperature.
One-step preparation and characterization of poly(propyleneimine) dendrimer-protected silver nanoclusters

Highly stable silver nanoclusters with narrow size distribution have been prepared by heating a third-generation poly(propyleneimine) dendrimer/AgNO3 aqueous solution without the additional step of introducing other reducing agents and protect agents. UV-vis absorption, transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), and X-ray diffraction (XRD) have been used to characterize the resulting products. The as-obtained sample was in coexistence of Ag and Ag2O. It also suggested that increasing temperature resulted in both the decrease in number of small particles and the increase in size of large particles.
Contribution of EO data to offshore wind energy planning

Scatterometer winds from QuikSCAT has been used in the North Sea for characterizing the offshore wind climate (Karagali et al. 2014). Scatterometer wind data has lower spatial resolution but much higher temporal resolution than SAR. The scatterometer data has been combined with satellite SAR data (Hasager et al. 2015b). Figure 6 shows a map on the wind energy density in the North Sea combined from QuikSCAT, ASCAT and Envisat ASAR.
Direct Angular Rate Estimation Without Event Motion-Compensation At High Angular Rates

Feature-based methods are a popular method for camera state estimation using event cameras. Due to the spatiotemporal nature of events, all event images exhibit smearing of events analogous to motion blur for a camera under motion. As such, events must be motion compensated to derive a sharp event image. However, this presents a causality dilemma where motion prior is required to unsmear the events, but a sharp event image is required to estimate motion. While it is possible to use the IMU to develop motion prior, it has been shown that the limited dynamic range of $\pm \mathbf{2000}^{\circ}/\mathrm{s}$ is insufficient for high angular rate rotorcrafts. Furthermore, smoothing of motion-compensated images due to actual event detection time latency in event cameras severely limits the performance of feature-based methods at high angular rates. This paper proposes a Fourier-based angular rate estimator capable of estimating angular rates directly on non-motion compensated event images. This method circumvents the need for external motion priors in camera state estimation and sidesteps problematic smoothing of features in the spatial domain due to motion blur. Lastly, using an NVIDIA Jetson Xavier NX, the algorithm is demonstrated to be real-time performant up to 3960°/s.
3-D Reconstruction Using Monocular Camera and Lights: Multi-View Photometric Stereo for Non-Stationary Robots

This paper proposes a novel underwater Multi-View Photometric Stereo (MVPS) framework for reconstructing scenes in 3-D with a non-stationary low-cost robot equipped with a monocular camera and fixed lights. The underwater realm is the primary focus of study here, due to the challenges in utilizing underwater camera imagery and lack of low-cost reliable localization systems. Previous underwater PS approaches provided accurate scene reconstruction results, but assumed that the robot was stationary at the bottom. This assumption is limiting, as many artifacts, reefs, and man-made structures are large and meters above the bottom. Our proposed MVPS framework relaxes the stationarity assumption by utilizing a monocular SLAM system to estimate small robot motions and extract an initial sparse feature map. To compensate for the scale inconsistency in monocular SLAM output, our MVPS optimization scheme collectively estimates a high-quality, dense 3-D reconstruction and corrects the camera pose estimates. We also present an attenuation and camera-light extrinsic parameter calibration method for non-stationary robots. Finally, validation experiments with a BlueROV2 demonstrated the low-cost capability of producing high-quality scene reconstructions. Overall, this work is the foundation of an active perception pipeline for robots (i.e., underwater, ground, and aerial) to explore and map complex structures in high accuracy and resolution with an inexpensive sensor-light configuration.
The chemistry of SH+ in shocked interstellar gas.

On a mesure les coefficients des reactions endothermiques de SH n + (n=0, 1, 2) avec H 2 et avec des atomes H, en fonction de l'energie cinetique du centre de masse ion-neutre. On considere la formation de l'ion SH + au cours de chocs magnetiques (MHD) et non magnetiques
Floating Offshore Wind Farm Control via Turbine Repositioning with Aerodynamic Force*

This paper overviews a wind farm control technique via turbine repositioning, which is exclusively applied to floating offshore wind turbines. The wind turbines are repositioned to modify the wind farm layout based on the wind condition and the power demand, in order to maximize the wind farm efficiency. The repositioning mechanism which manipulates the aerodynamic force by means of conventional wind turbine control inputs is explained. Potential advantages of the turbine repositioning for wind farm control are demonstrated in simulations using the medium-fidelity wind farm simulator FAST.Farm developed by the National Renewable Energy Laboratory (NREL) and an example floating offshore wind farm which consists of three NREL 5MW semi-submersible baseline wind turbines. Finally, potential future research directions in this wind farm control technique are provided.
The role of Southern Ocean mixing and upwelling in glacial-interglacial atmospheric CO2 change

Decreased ventilation of the Southern Ocean in glacial time is implicated in most explanations of lower glacial atmospheric CO2. Today, the deep (>2000 m) ocean south of the Polar Front is rapidly ventilated from below, with the interaction of deep currents with topography driving high mixing rates well up into the water column. We show from a buoyancy budget that mixing rates are high in all the deepwaters of the Southern Ocean. Between the surface and∼2000m depth, water is upwelled by a residual meridional overturning that is directly linked to buoyancy fluxes through the ocean surface. Combined with the rapid deep mixing, this upwelling serves to return deep water to the surface on a short time scale. We propose two new mechanisms by which, in glacial time, the deep Southern Ocean may have been more isolated from the surface. Firstly, the deep ocean appears to have been more stratified because of denser bottom water resulting from intense sea ice formation near Antarctica. The greater stratification would have slowed the deep mixing. Secondly, subzero atmospheric temperatures may have meant that the present-day buoyancy flux from the atmosphere to the ocean surface was reduced or reversed. This in turn would have reduced or eliminated the upwelling (contrary to a common assumption, upwelling is not solely a function of the wind stress but is coupled to the air–sea buoyancy flux too). The observed very close link between Antarctic temperatures and atmospheric CO2 could then be explained as a natural consequence of the connection between the air–sea buoyancy flux and upwelling in the Southern Ocean, if slower ventilation of the Southern Ocean led to lower atmospheric CO2. Here we use a box model, similar to those of previous authors, to show that weaker mixing and reduced upwelling in the Southern Ocean can explain the low glacial atmospheric CO2 in such a formulation.
On microemulsion phase behavior and the monomeric solubility of surfactant

In this paper we highlight the advantageous features of both short- and long-chain surfactant systems in determining the most important properties of three-phase bodies and genuine microemulsions. To this end first the phase behavior of the simple system H2O–n-dodecane–C4E1 (n-butyl monoglycol ether) is discussed. From temperature–concentration sections through the phase prism at various water-to-oil ratios, a number of isothermal Gibbs triangles are constructed, which can quantitatively be compared with theories. Furthermore, the critical tie-lines of the three-phase body have been precisely determined. From these measurements it is evident that there is a non-negligible monomeric solubility of the surfactant in the excess phases. For long-chain surfactant systems, the more efficient the surfactant, the larger is the size of the microstructure of the microemulsion. We report a striking correlation between the efficiency of a surfactant and its monomeric solubility in the excess phases for 23 systems of the type H2O–n-alkane–CiEj. These findings suggest that the monomeric solubility of the surfactant in oil and water might be the key to describing the main features of these microemulsion systems.
Monocular Reactive Collision Avoidance for MAV Teleoperation with Deep Reinforcement Learning

Enabling Micro Aerial Vehicles (MAVs) with semi-autonomous capabilities to assist their teleoperation is crucial in several applications. Remote human operators do not have, in general, the situational awareness to perceive obstacles near the drone, nor the readiness to provide commands to avoid collisions. In this work, we devise a novel teleoperation setting that asks the operator to provide a simple high-level signal encoding the speed and the direction they expect the drone to follow. We then endow the MAV with an end-to-end Deep Reinforcement Learning (DRL) model that computes control commands to track the desired trajectory while performing collision avoidance. Differently from State-of-the-Art (SotA) works, it allows the robot to move freely in the 3D space, requires only the current RGB image captured by a monocular camera and the current robot position, and does not make any assumption about obstacle shape and size. We show the effectiveness and the generalization capabilities of our strategy by comparing it against a SotA baseline in photorealistic simulated environments.
Response of wheat seed to priming combinations

An experiment using the randomized complete block design in three replications was conducted in 2013 under laboratory conditions to study the effects of different treatments of hydro-priming and osmo-priming on seed germination of the Darya cultivar of wheat. The treatments studied included subjecting the seeds for 12 or 24 hours to polyethylene glycol 6000 at three concentrations (5, 10, and 15 percent), potassium nitrate at three concentrations (1, 2 and 3 percent), potassium chloride at three concentrations (1, 2 and 4 percent), and a control treatment of distilled water. Results obtained showed that the rates of germination, total percentages of germination, percentages of normal seedlings, lengths of the radicles and sprouts, length ratios of root to shoot, lengths of the seedlings, dry weight of radicles and weight ratios of root to shoot were statistically significant at one percent level, but the dry weight of the sprouts and seedling weren't statistically significant. The maximum germination rate (22.11) was achieved in the treatment of 8 hrs using distilled water, and the minimum germination rate (7.61) in the 16 hrs treatments with four percent KCL. The highest total germination rate (100) was observed in the treatments of distilled water with 16 hrs, where as the lowest (40.67) observed in the 16 hrs treatment using 4 percent KCL. The results also indicated that the highest percentages of normal seedlings (95.33 and 100) belonged to the 8 and 16 hrs treatment with distilled water respectively, and to the 8 hrs treatment of using five percent PEG (92.67) and 1 percent KNO3 at 16 hrs (96.67), and the lowest (40.00) was that of the 16 hrs treatment with four percent KCL. Results observed also suggested that the factors measured, including the rate and the percentage of seed germination and also the lengths of the radicles and sprouts and seedlings, exhibited an ascending trend when higher concentrations of osmo-priming compounds were used. These compounds showed their greatest effects when used at low concentrations.
Atomic layer epitaxy of AlGaAs

Atomic layer epitaxy (ALE) has been employed to grow AlGaAs in the temperature range 550–700 °C. Monolayer growth was achieved independent of the column III flux. Al incorporates during ALE more efficiently than in metalorganic chemical vapor deposition (MOCVD). The ALE films grown at low temperature have superior photoluminescence properties when compared with the MOCVD‐grown films. The as‐grown ALE films are p type with carrier concentrations in the 1017–1019/cm3 range, depending on the growth conditions.
Generalized correlations in terms of polarizability for van der Waals interaction potential parameter calculations

General correlations between van der Waals interaction potential parameters and polarizabilities of the interacting neutral–neutral partners of any nature are presented and discussed. To ensure the full applicability of the correlations, an evaluation of the long‐range interaction constants is performed in terms of the Slater–Kirkwood approximation whose numerical coefficients, having the meaning of effective electron numbers, are estimated interpolating the values deduced by theoretical considerations. The values of the long‐range constants so obtained are compared satisfactorily with the available experimental ones. The correlations are tested successfully over practically all systems characterized experimentally. Their use to predict the parameters of unknown systems is suggested.
The Effect of the Rotation of Groups about Bonds on Optical Rotatory Power

It is shown that the numerical value of the optical activity of an optically active compound is markedly reduced if the groups surrounding the asymmetric atoms in the compound possess a threefold axial symmetry about the bonds connecting them with the asymmetric atoms. This threefold symmetry may be either inherent in the groups themselves, or it may be acquired by them through the free rotation of the groups about these bonds or by their orienting themselves to equal extents in each of the three possible equilibrium positions about each bond. The order of magnitude of the numerical value of the optical activity is thus a measure of the freedom of orientation about single bonds of the groups in an asymmetric molecule. That this effect is actually a dominant factor in determining the order of magnitude of the optical activity is proved by the contrast in the optical activities of cyclic and open chain compounds. It is shown to have an important effect on the temperature coefficient of optical activity and .
Trajectory error compensation for optimal control of UMA-2 – a climbing robot executing maintenance operation in harsh environment

UMA-2 is a wheeled mobile platform equipped with a vacuum adhesion system, eight actuated joints and four passive ones, designed to climb vertical and curved surfaces. The platform can perform maintenance tasks such as corrosion removal and cleaning with grinding while climbing. The quality of the repairing process is largely affected by grinding process parameters including tool forces, toolpath and the robot trajectory accuracy. The current work introduces a trajectory analysis and adaptation model to control the UMA-2 platform to ensure specific surface quality KPIs and incorporating the effects of robot compliancy. The proposed trajectory analysis has been extensively validated through experimental campaigns representative of maintenance in wind power industry.
Learning Personalised Human Sit-to-Stand Motion Strategies via Inverse Musculoskeletal Optimal Control

Physically assistive robots and exoskeletons have great potential to help humans with a wide variety of collaborative tasks. However, a challenging aspect of the control of such devices is to accurately model or predict human behaviour, which can be highly individual and personalised. In this work, we implement a framework for learning subject-specific models of underlying human motion strategies using inverse musculoskeletal optimal control. We apply this framework to a specific motion task: the sit-to-stand transition. By collecting sit-to-stand data from 4 subjects with and without perturbations, we show that humans modulate their sit-to-stand strategy in the presence of instability, and learn the corresponding models of these strategies. In the future, the personalised motion strategies resulting from this framework could be used to inform the design of real-time assistance strategies for human-robot collaboration problems.
Theory, Measurement, and Origin of Optical Activity in Benzil Crystal

ABSTRACT The three coupled oscillator model and its application to the explanation of optical-rotatory dispersion and circular dichroism of benzil crystal is discussed. The previously measured experimental data are approximated by the theoretical set of formulas provided by this model. The twelve-term formula, which was computed using our computer program, is derived from the interpretation of the optical-rotatory dispersion of benzil. Similarly, the circular-dichroism data are analyzed. Both the previously published experimental data and the latest measurements are used for this reason. The obtained results are compared and discussed with respect to the origin of the optical activity occurring in benzil crystal.
Influence of ultrasonic disintegration on the dewaterability of waste activated sludge

Ultrasound can be used to disintegrate waste activated sludge (WAS), resulting in changes in sludge dewaterability. To observe and explain the change in sludge dewatering properties before and after ultrasonic disintegration, the specific resistance to filtration (SRF), capillary suction time (CST), content of biopolymers (proteins + polysaccharides), and free water in the sludge before and after disintegration were examined. Despite the degradation of extracellular polymeric substances (EPS), the sludge dewatering properties worsened after disintegration. This result is attributed to two changes in the sludge, one being the effect of the water retained by the biopolymers and the other being the adsorption effect of the fine sludge particles for free water.