Key Physical Parameters Research Articles

On-line Inertia Measurement of Unmanned Aerial Vehicles using on board Sensors and Bifilar Pendulum

Identification of a dynamical model and its parameter estimation is one of the fundamental problems in field of robotics and system dynamics modelling. For the general case of object motion with six degrees of freedom (6- DOF), such as in the case of Unmanned Aerial Vehicle (UAV), the key physical parameters are its mass and tensor of inertias. Even though UAV mass and its geometry/topology are easily obtainable, an identification of inertia tensor is difficult considering that is not measurable by static tests. This paper presents a simple and effective method for on-line estimation of a rigid-body inertia based on two-wire pendulum and integrated sensor system. Herein, the test subject (i.e. UAV) is suspended by two thin parallel wires in such a way to form a bifilar torsional pendulum about the vertical axis. Using on-board sensors from UAV flight controller (FC) unit, the pendulum oscillations are recorded and processed to obtain trend-free and noise-free signals used in the final inertia estimation phase based on inertia- related properties of pendulum oscillations. The proposed identification algorithm is verified experimentally for two typical cases of suspended objects related to UAV control box and full UAV configuration.

Electro-mechanical vibration analysis of functionally graded piezoelectric porous plates in the translation state

To provide reference for aerospace structural design, electro-mechanical vibrations of functionally graded piezoelectric material (FGPM) plates carrying porosities in the translation state are investigated. A modified power law formulation is employed to depict the material properties of the plates in the thickness direction. Three terms of inertial forces are taken into account due to the translation of plates. The geometrical nonlinearity is considered by adopting the von Kármán non-linear relations. Using the d’Alembert's principle, the nonlinear governing equation of the out-of-plane motion of the plates is derived. The equation is further discretized to a system of ordinary differential equations using the Galerkin method, which are subsequently solved via the harmonic balance method. Then, the approximate analytical results are validated by utilizing the adaptive step-size fourth-order Runge-Kutta technique. Additionally, the stability of the steady state responses is examined by means of the perturbation technique. Linear and nonlinear vibration analyses are both carried out and results display some interesting dynamic phenomenon for translational porous FGPM plates. Parametric study shows that the vibration characteristics of the present inhomogeneous structure depend on several key physical parameters.

Nonlinear dynamics and stability of microsystems engineering elements

Subject of Research. Static and dynamic problems of coupled electroelasticity are considered for electrostatic (capacitive) transducers used in sensors and actuators based on nano- and microsystem technology of various applications. Method. Above-mentioned problems are analyzed by mathematical apparatus of nonlinear mechanics and bifurcation theory as well as modern numerical methods, including numerical continuation techniques for nonlinear boundary-value problems of mathematical physics. Main Results. Comparative analysis of analytical and numerical methods was performed for nonlinear static and dynamic boundary-value problems of electroelasticity for microsystems and nanosystems engineering. Basic discrete (nonlinear nano/micro-electromechanical oscillators) and distributed (membranes, plates) electromechanical models were considered. Equilibrium forms, their stability and bifurcations were studied for afore-named elastic systems under the influence of electric fields of various configurations. Bifurcation diagrams were derived depending on key physical parameters. Nonlinear dynamic problems for elastic systems at time-varying electric fields were also considered. Practical Relevance. The present research is of considerable practical significance because it reveals and analyzes qualitatively the elastic elements properties and characteristics that are important for nano/micro-system design, such as equilibria structure and stability, amplitude and force response of the system, etc. Used methods and mathematical formulations can be applied in the design process of micromechanical accelerometers and gyroscopes, pressure sensors, micro-pumps, capacitive micro-machined ultrasound transducers, radio-frequency and optical switches, electromagnetic energy harvesting systems and biomedical devices.

Physical-Based Analytical Model of Amorphous InGaZnO TFTs Including Deep, Tail, and Free States

Amorphous InGaZnO (a-IGZO) is a candidate material for thin-film transistors (TFTs) owing to its large electron mobility and good uniformity over large area. a-IGZO TFTs drain current models are essential for further pushing both a-IGZO TFTs technology and circuit design. In this paper, we propose a simple physical-based and analytical model of the drain current of a-IGZO TFTs. The model is valid in both non degenerate and degenerate conduction and it accounts for deep interface states, tail localized states, and free delocalized band states. The model is validated with the measurements of both coplanar and staggered a-IGZO TFTs. It provides key physical and material parameters of the transistor and, owing to its class $C^{\infty }$ formulation, it can be straightforwardly implemented in circuit simulators.

Obstacle contained system (OCS) design method and its application in valve core orifice design of pilot-control globe valve

With the development of the society and the times, traditional parametric design methods are witnessing a severe challenge due to the more and more complex physical systems. Thus, developing novel parametric analysis methods is very important for dealing with complex physical systems, refining useful parameters from numerous data, and proposing accurate prediction formulas. A spring slider system, a direct-current circuit system, a pipeline pressure drop system and a steady heat transfer model of flat plate system were described from the point of systemic parametric analysis method. Then, the key physical parameters in above four systems were summarized. Based on the comparative results, a novel systemic parametric design method, obstacle contained system (OCS) design method, was proposed. The OCS was made up of three elements:an obstacle element, a pass body element and a D-value element. With an abundant accurate data pole, the OCS design method could build the direct relationship of the obstacle element and the D-value element, which meant the simplification of the physical models and much easier to get relatively accurate results. Meanwhile, the design of pilot-control globe valve orifice was checked with both the OCS design method and the numerical simulation. The diameter of orifice on the valve core could influence the pressure difference and the maximum vapor rate inside pilot-control globe valves. Achieved by two different methods, the OCS design method and the numerical simulation, the results showed that the effects of orifice diameters on the pressure difference and the maximum vapor rate under different inlet velocities, were within 2% errors, which was reasonable and acceptable for the engineering application. In other words, the OCS design method was credible for parametric analysis. In future, the OCS design method has a broad application prospect to analyze various types of physical models especially in the era of big data.

Universal poroelastic mechanism for hydraulic signals in biomimetic and natural branches

Plants constantly undergo external mechanical loads such as wind or touch and respond to these stimuli by acclimating their growth processes. A fascinating feature of this mechanical-induced growth response is that it can occur rapidly and at long distance from the initial site of stimulation, suggesting the existence of a fast signal that propagates across the whole plant. The nature and origin of the signal is still not understood, but it has been recently suggested that it could be purely mechanical and originate from the coupling between the local deformation of the tissues (bending) and the water pressure in the plant vascular system. Here, we address the physical origin of this hydromechanical coupling using a biomimetic strategy. We designed soft artificial branches perforated with longitudinal liquid-filled channels that mimic the basic features of natural stems and branches. In response to bending, a strong overpressure is generated in the channels that varies quadratically with the bending curvature. A model based on a mechanism analogous to the ovalization of hollow tubes enables us to predict quantitatively this nonlinear poroelastic response and identify the key physical parameters that control the generation of the pressure pulse. Further experiments conducted on natural tree branches reveal the same phenomenology. Once rescaled by the model prediction, both the biomimetic and natural branches fall on the same master curve, enlightening the universality of our poroelastic mechanism for the generation of hydraulic signals in plants.

Universal Equations for the Coalescence Probability and Long-Term Size Stability of Phospholipid-Coated Monodisperse Microbubbles Formed by Flow Focusing.

Resonantly driven monodisperse phospholipid-coated microbubbles are expected to substantially increase the sensitivity and efficiency in contrast-enhanced ultrasound imaging and therapy. They can be produced in a microfluidic flow-focusing device, but questions remain as to the role of the device geometry, the liquid and gas flow, and the phospholipid formulation on bubble stability. Here, we develop a model based on simple continuum mechanics equations that reveals the scaling of the coalescence probability with the key physical parameters. It is used to characterize short-term coalescence behavior and long-term size stability as a function of flow-focusing geometry, bulk viscosity, lipid cosolvent mass fraction, lipid concentration, lipopolymer molecular weight, and lipopolymer molar fraction. All collected data collapse on two master curves given by universal equations for the coalescence probability and the long-term size stability. This work is therefore a route to a more fundamental understanding of the physicochemical monolayer properties of microfluidically formed bubbles and their coalescence behavior in a flow-focusing device.

Open and Academia: Datasets and Tools to Accelerate Electrochemical Science and Engineering

Electrochemistry has a strong scholarly legacy of bench-top scale “small” science. Over the past two decades, societal demand for improved electrochemical power sources—batteries and fuel cells—has driven a push for accelerating the process of turning a scientific discovery into a technology demonstration and, ultimately, an improved product. We discuss our lab’s effort to create valuable open source data sets and analysis tool. We are taking the most commonly used and cited full-physics lithium-ion battery model as the basis for generating a large library of impedance spectra that can be compared to experimental data. We have developed a data analysis and visualization tool to compare experiments and model in order to extract key physical parameters of the battery under test. We see open source datasets and analysis tools as complementary to the broader movement by ECS to Free the Science through open access.

Is there a path from cuprates towards room-temperature superconductivity?

A brief account is presented of an extensive experiment performed at Brookhaven National Laboratory, aimed at understanding the nature of high-temperature superconductivity in cuprates. Over the course of the last 12 years, over 2000 films of the prototypical high- $$T_\mathrm{c}$$ superconductor, $$\hbox {La}_{2-{x}}\hbox {Sr}_{{x}}\hbox {CuO}_{4}$$ , have been synthesized using atomic-layer-by-layer molecular beam epitaxy (ALL-MBE), characterized by a range of techniques, and patterned into devices. These were used to measure accurately the key physical parameters in both the superconducting and the normal states, and establish their precise dependence on doping, temperature, and external fields. The results bring in some great surprises, challenge the commonly held beliefs, rule out many theoretical models, and point to a new path for raising $$T_\mathrm{c}$$ even further.

How Do Type Ia Supernova Nebular Spectra Depend on Explosion Properties? Insights from Systematic Non-LTE Modeling

Abstract We present a radiative transfer code to model the nebular phase spectra of supernovae (SNe) in non-LTE (NLTE). We apply it to a systematic study of SNe Ia using parameterized 1D models and show how nebular spectral features depend on key physical parameters, such as the time since explosion, total ejecta mass, kinetic energy, radial density profile, and the masses of 56Ni, intermediate-mass elements, and stable iron-group elements. We also quantify the impact of uncertainties in atomic data inputs. We find the following. (1) The main features of SN Ia nebular spectra are relatively insensitive to most physical parameters. Degeneracy among parameters precludes a unique determination of the ejecta properties from spectral fitting. In particular, features can be equally well fit with generic Chandrasekhar mass ( ), sub- , and super- models. (2) A sizable (≳0.1 ) central region of stable iron-group elements, often claimed as evidence for models, is not essential to fit the optical spectra and may produce an unusual flat-top [Co iii] profile. (3) The strength of [S iii] emission near 9500 Å can provide a useful diagnostic of explosion nucleosynthesis. (4) Substantial amounts (≳0.1 ) of unburned C/O mixed throughout the ejecta produce [O iii] emission not seen in observations. (5) Shifts in the wavelength of line peaks can arise from line-blending effects. (6) The steepness of the ejecta density profile affects the line shapes, offering a constraint on explosion models. (7) Uncertainties in atomic data limit the ability to infer physical parameters.

Influence of recycled coarse aggregates on permeability of fresh concrete

The following work is an experimental study of the behaviour of very early-age concrete. Six different concretes, four of them containing recycled coarse aggregates were studied for the first 2.5 h. The studies were carried out in a ventilated tunnel in order to imitate severe desiccation conditions. In order to indirectly obtain the permeability coefficient, settlement, capillary depression and evaporation were measured for all six concretes. The initial permeability coefficient of each concrete is determined starting from initial bleeding rate. The use of recycled coarse aggregates leads to a high bleeding rate for high water to cement ratios. Permeability coefficients at air entry are then determined starting from capillary depression gradients. Recycled coarse aggregates do not seem to influence the air entry value which is highly dependent on the paste quality. At air entry, the permeability coefficient of recycled coarse aggregates concrete mixes is higher than that of natural aggregates concrete mixes. At high evaporation rates, in severe desiccation conditions, recycled coarse aggregates seem to reduce bleeding for mixture with low water cement ratios. Permeability coefficient is a key physical parameter to understand drying of fresh concrete.

Herschel survey and modelling of externally-illuminated photoevaporating protoplanetary disks.

Protoplanetary disks undergo substantial mass-loss by photoevaporation, a mechanism which is crucial to their dynamical evolution. However, the processes regulating the gas energetics have not been well constrained by observations so far. We aim at studying the processes involved in disk photoevaporation when it is driven by far-UV photons (i.e. 6 < E < 13.6 eV). We present a unique Herschel survey and new ALMA observations of four externally-illuminated photoevaporating disks (a.k.a. proplyds). For the analysis of these data, we developed a 1D model of the photodissociation region (PDR) of a proplyd, based on the Meudon PDR code and we computed the far infrared line emission. With this model, we successfully reproduce most of the observations and derive key physical parameters, i.e. densities at the disk surface of about 106 cm-3 and local gas temperatures of about 1000 K. Our modelling suggests that all studied disks are found in a transitional regime resulting from the interplay between several heating and cooling processes that we identify. These differ from those dominating in classical PDRs i.e. grain photo-electric effect and cooling by [OI] and [CII] FIR lines. This specific energetic regime is associated to an equilibrium dynamical point of the photoevaporation flow: the mass-loss rate is self-regulated to keep the envelope column density at a value that maintains the temperature at the disk surface around 1000 K. From the physical parameters derived from our best-fit models, we estimate mass-loss rates - of the order of 10-7 M⊙/yr - that are in agreement with earlier spectroscopic observation of ionised gas tracers. This holds only if we assume photoevaporation in the supercritical regime where the evaporation flow is launched from the disk surface at sound speed. We have identified the energetic regime regulating FUV-photoevaporation in proplyds. This regime could be implemented into models of the dynamical evolution of protoplanetary disks.

Experimental and Numerical Investigation of Interdie Thermal Resistance in Three-Dimensional Integrated Circuits

Three-dimensional integrated circuits (3D ICs) attract much interest due to several advantages over traditional microelectronics design, such as electrical performance improvement and reducing interconnect delay. While the power density of 3D ICs increases because of vertical integration, the available substrate area for heat removal does not change. Thermal modeling of 3D ICs is important for improving thermal and electrical performance. Experimental investigation on the thermal measurement of 3D ICs and determination of key physical parameters in 3D ICs thermal design are curtail. One such important parameter in thermal analysis is the interdie thermal resistance between adjacent die bonded together. This paper describes an experimental method to measure the value of interdie thermal resistance between two adjacent dies in a 3D IC. The effect of heating one die on the temperature of the other die in a two-die stack is measured over a short time period using high-speed data acquisition to negate the effect of boundary conditions. Numerical simulation is performed and based on a comparison between experimental data and the numerical model, the interdie thermal resistance between the two dies is determined. A theoretical model is also developed to estimate the value of the interdie thermal resistance. Results from this paper are expected to assist in thermal design and management of 3D ICs.

Chemiluminescent determination of cyromazine in milk samples using copper(III) chelate-Triton X-100 by flow injection analysis

Cyromazine(CYR) was determined in milk samples using copper(III) chelate-Triton X-100 chemiluminescence(CL) system associated with flow-injection(FI) in KOH medium. The relative CL intensity for CYR concentration was linear over the range of 5×10–4―10 μg/mL(R 2=0.9990, n=11) with injection rate of 160 h–1 and the relative standard deviation(RSD, n=4) of 1.2%―2.6%. The limit of detection(LOD) for signal-to-noise ratio of 3 was 1.5×10–4 μg/mL. The influences of key chemical and physical parameters, some major fresh water ions at their maximum admissible concentrations and a number of pesticides were examined as potential interferences. The concentrations of CYR in spiked milk samples were successfully determined by the proposed method and the results were in good agreement with the previously reported HPLC method, having recovery range of (92±4)%―(106±2)%. The possible CL reaction mechanism for copper(III) complex-Triton X-100-CYR was also briefly discussed.

A broad-band self-consistent modelling of the X-ray spectrum of 4U 1626−67

The accretion-powered X-ray pulsar 4U 1626--67 is one of the few highly magnetized pulsars that accretes through Roche-lobe overflow from a low-mass companion. The characteristics of its broadband spectrum are similar to those of X-ray pulsars hosted in a high-mass X-ray binary systems, with a broad resonant cyclotron scattering feature (CRSF) at $\sim$37 keV. In this work, we examine the pulse-resolved and the pulse-averaged broadband spectrum using data from NuSTAR and Swift. We use the Becker & Wolff model of bulk+thermal Comptonization to infer key physical parameters of the accretion column flow and a broadband model for the disk reflected spectrum. In the softer X-ray band, we need to add a soft black-body component with $kT_{\rm bb}$ $\sim$0.5 keV, whose characteristics indicate a possible origin from the neutron star surface. Residuals suggest that the shape of the cyclotron line could be more satisfactorily fitted using a narrow core and broader wings and, at higher energies, a second harmonic could be present at $\sim$61 keV.

Key physical parameters of hawthorn leaf granules by stepwise regression analysis method

The purpose of this study was to investigate the effect of key physical properties of hawthorn leaf granule on its dissolution behavior. Hawthorn leaves extract was utilized as a model drug. The extract was mixed with microcrystalline cellulose or starch with the same ratio by using different methods. Appropriate amount of lubricant and disintegrating agent was added into part of the mixed powder, and then the granules were prepared by using extrusion granulation and high shear granulation. The granules dissolution behavior was evaluated by using equilibrium dissolution quantity and dissolution rate constant of the hypericin as the indicators. Then the effect of physical properties on dissolution behavior was analyzed through the stepwise regression analysis method. The equilibrium dissolution quantity of hypericin and adsorption heat constant in hawthorn leaves were positively correlated with the monolayer adsorption capacity and negatively correlated with the moisture absorption rate constant. The dissolution rate constants were decreased with the increase of Hausner rate, monolayer adsorption capacity and adsorption heat constant, and were increased with the increase of Carr index and specific surface area. Adsorption heat constant, monolayer adsorption capacity, moisture absorption rate constant, Carr index and specific surface area were the key physical properties of hawthorn leaf granule to affect its dissolution behavior.

A Novel Multi-stage Looped Thermoacoustic Heat Engine Using Assembly of Elastic Membrane and a Solid Mass

Abstract A compact looped traveling-wave thermoacoustic heat engine (LTTHE) using an assembly of an elastic membrane (EM) and a solid-mass plate (SP) acting as a resonance unit is proposed in this paper. In the novel configuration, the novel resonance assembly substitutes for the traditional resonance tube to reduce the axial size of the system effectively, leading to a compact-size system. In addition, multiple identical engine units are included in a closed loop to realize efficient thermoacoustic conversion and efficient acoustical transmission. In this paper, a typical three-stage thermoacoustic heat engine operating around 300 Hz is chosen to be studied and optimized numerically based on a thermoacoustic model. Firstly, the influence of key physical parameters on no-load thermodynamic performance is investigated. Then, the system output characteristics are further discussed for a better understanding of the thermoacoustic operation. According to the calculated results, it is shown that this novel thermoacoustic heat engine has the potential of realizing a compact-size and efficient system operating around 300 Hz frequency.

Hayabusa-2 mission target asteroid 162173 Ryugu (1999 JU3): Searching for the object’s spin-axis orientation

The JAXA Hayabusa-2 mission was approved in 2010 and launched on December 3, 2014. The spacecraft will arrive at the near-Earth asteroid 162173 Ryugu in 2018 where it will perform a survey, land and obtain surface material, then depart in Dec 2019 and return to Earth in Dec 2020. We observed Ryugu with the Herschel Space Observatory in Apr 2012 at far-IR thermal wavelengths, supported by several ground-based observations to obtain optical lightcurves. We reanalysed previously published Subaru-COMICS and AKARI-IRC observations and merged them with a Spitzer-IRS data set. In addition, we used a large set of Spitzer-IRAC observations obtained in the period Jan to May, 2013. The data set includes two complete rotational lightcurves and a series of ten "point-and-shoot" observations. The almost spherical shape of the target together with the insufficient lightcurve quality forced us to combine radiometric and lightcurve inversion techniques in different ways to find the object's key physical and thermal parameters. We find that the solution which best matches our data sets leads to this C class asteroid having a retrograde rotation with a spin-axis orientation of (lambda = 310-340 deg; beta = -40+/-15 deg) in ecliptic coordinates, an effective diameter (of an equal-volume sphere) of 850 to 880 m, a geometric albedo of 0.044 to 0.050 and a thermal inertia in the range 150 to 300 Jm-2s-0.5K-1. Based on estimated thermal conductivities of the top-layer surface in the range 0.1 to 0.6 WK-1m-1, we calculated that the grain sizes are approximately equal to between 1 and 10 mm. The finely constrained values for this asteroid serve as a `design reference model', which is currently used for various planning, operational and modelling purposes by the Hayabusa2 team.

Magnetic and structural properties of Fe–Co nanowires fabricated by matrix synthesis in the pores of track membranes

Fe1-x Co x nanowires are obtained by electrochemical deposition into the pores of track-etched membranes. The characteristics of the growth process that allow controlling the length and aspect ratio of the nanowires are established. The elemental composition and magnetic properties of the nanowires depend on the diameter of the track-etched pores, which varies from 30 to 200 nm, and the electrochemical potential U (650–850 mV), which determines the nanowire growth rate. According to the results of elemental analysis and the Mossbauer spectroscopy data, the Co content in Fe1-x Co x lies in the range of x=0.20−0.25. It is found that the orientation of the magnetic moment of Fe–Co nanoparticles in the wires depends both on the track pore size d and on the nanowire growth rate. Thus, the magnetic moments in nanowires grown in 50-nm-diameter pores are oriented within 0°–40° with respect to the nanowire axis. The magnetic properties of the nanowires are explained in the framework of a theoretical model describing the magnetic dynamics of nanocomposites, which was extended to include the relaxation of the magnetization vector and to take into account interaction between the particles. The key physical parameters important for the technological applications of the nanowires are determined, their dependence on the nanowire growth conditions is traced, and the possibility of controlling them is established.

Simulation on gas transport in shale: The coupling of free and adsorbed gas

The shale reservoirs contain not only a lot of nano-micro scale pores, but the coupling phenomenon between free and adsorbed gas, which leads to complexity when estimating shale-gas production. Currently, different models have been applied to describe the gas transport in shale, especially in different flow regions. However, the role played by adsorbed gas on the production performance is still difficult to evaluate due to the fact that the coupling of free and adsorbed gas is rarely considered.This study incorporates various gas transport mechanisms in nanopores including viscous flow, Knudsen diffusion (combination of both is slip flow) and surface diffusion of adsorbed gas with a nonlinear and non-equilibrium gas adsorption-desorption kinetics to formulate a simplified model for studying the dynamic production performance for multi-stage fractured horizontal wells in shale gas reservoirs. A method is developed and used to evaluate the respective contributions from the stored free gas and the adsorbed gas to the total gas production rate. Sensitivity of the production rate to key physical parameters is performed. It is found that desorption process dominates the production within very short times after the start of production. The production rate is shown to be particularly sensitive to the pore size and porosity while largely unaffected by the surface diffusion of the adsorbed gas with the fact that the surface diffusion is a much slower process compared with the diffusion of free gas, especially when the permeability in Stimulated Reservoir Volume (SRV) is significantly enhanced by fracture networks.