Physical Parameters Of Structure Research Articles

Dependence of longitudinal magnetic permeability and transverse conductivity on mechanical loads on the shaft

This research deals with transformer type eddy-current transducer connected in differential circuit and it also proposes method for real-time evaluating mechanical tension in metal cylindrical products. The authors have proposed contactless method for estimating product mechanical deformation which is based on utilizing correlation connections between metals’ electromagnetic properties and their structural condition. The authors have introduced a generalized normalized informative magnetic parameter and on its basis obtain basic transform functions aided for determining increments of relative magnetic permeability and specific electric conductivity of product under load comparatively to standard sample. The article shows the possibility of using the differential method to increase the sensitivity of the evaluation of cylindrical products mechanical parameters. The authors have developed a physical model of an electromagnetic transducer with a product that is subjected to torsion, a theoretical justification is given at the level of the domain structure of the material under study and electromagnetic phenomena. The authors have created an experimental setup, the results of experimental studies of the influence of the mechanical moment caused by the torsion of an object on its electromagnetic properties were obtained. The research has proposed amplitude and phase methods for evaluating mechanical stresses. The results of the research allow to conclude, that there is an efficient transducer operating mode in the range 1 ≤ х ≤ 3, in which for η = 0,38 errors of mr and  estimation are less than 1% and 3% correspondingly. It is also noticeable, that in this range of x relative sensitivity of transducer is maximal. This allows us to create industrial devices for contactless multi-parameter evaluation of physical and mechanical parameters of metal products and structures. The obtained results of theoretical and experimental studies do not contradict the previously known laws of theoretical mechanics, which allows them to be widely used in the practice of nondestructive testing.

Enhancement of solar cell using two nanoparticles (Ag–Au)

In this paper, photovoltaics (PV)- or solar cells based on two types of nanoparticles have been investigated. The suggested four-layer solar cell model consists of metallic nanoparticle (Ag–Au) layers that are Si-based and covered by SiN. The transmission and reflection of the incident light on the structure model have been computed for different physical parameters of the structure. Higher transmission and lower reflections have been obtained leading to higher efficiency of the solar cells. The matrix model is used, and the numerical results obtained by MAPLE Software Program. The obtained results confirm that the nanoparticle solar cell structure can effectively enhance the efficiency of such structure model.

Study on simulation model and performance test of locomotive anti-skid valve

When studying the comprehensive performance of the anti-skid valve, the test of the curve characteristic lacks theoretical basis in the brake anti-skid process and the mathematical equations are difficult to derive. Take a domestic locomotive anti-skid valve as the research object. Combine with the physical structure parameters of the anti-skid valve and the working principle of inflating and exhausting. A simulation model of the anti-skid valve was established by using MATLAB/Simulink, which included the motion equation of valve core and diaphragm plate, electromagnetic suction equation of electromagnet and air chamber charging and exhausting equation. The characteristics of the air pressure curve of the anti-skid valve under different control signals were analyzed. In order to verify the correctness of the simulation model, a set of locomotive anti-skid valve comprehensive performance test bench based on STM32 was built for experimental verification. The results show that the simulation results are consistent with the experimental results, meet the test requirements, and verify the accuracy of the model. This model provides a theoretical basis for structural optimization of anti-skid valves and analysis of locomotive braking anti-skid performance.

Jet Geometry and Rate Estimate of Coincident Gamma-Ray Burst and Gravitational-wave Observations

Abstract Short gamma-ray burst (SGRB) progenitors have long been thought to be coalescing binary systems of two neutron stars (NSNS) or a neutron star and a black hole. The 2017 August 17th detection of the GW170817 gravitational-wave (GW) signal by Advanced LIGO and Advanced Virgo in coincidence with the electromagnetic observation of the SGRB GRB 170817A confirmed this scenario and provided new physical information on the nature of these astronomical events. We use SGRB observations by the Neil Gehrels Swift Observatory Burst Alert Telescope and GW170817/GRB 170817A observational data to estimate the detection rate of coincident GW and electromagnetic observations by a GW detector network and constrain the physical parameters of the SGRB jet structure. We estimate the rate of GW detections coincident with SGRB electromagnetic detections by the Fermi Gamma-ray Burst Monitor to be between ∼0.1 and ∼0.6 yr−1 in the third LIGO-Virgo observing run and between ∼0.3 and ∼1.8 yr−1 for the LIGO-Virgo-KAGRA network at design sensitivity. Assuming a structured model with a uniform ultrarelativistic jet surrounded by a region with power-law decay emission, we find the jet half-opening angle and the power-law decay exponent to be θ c ∼ 7°–22° and s ∼ 5–30 at a 1σ confidence level, respectively.

Dissipative sensing with low detection limit in a self-interference microring resonator

A dissipative sensing scheme based on a self-interference microring resonator (SIMRR), which is robust against lasing and microcavity frequency noise in the detecting system with a low noise level, is systematically investigated. The dependence of the performance of an SIMRR sensor in dispersive and dissipative sensing schemes on the physical structural parameters, e.g., the waveguide loss coefficient, the power coupling coefficient, the microring radius, and the initial sensing arm waveguide length in the SIMRR sensor, is studied. Based on the Cramer–Rao lower bound for parameter estimation, the detection limits of dispersive and dissipative sensing are theoretically and numerically analyzed, which demonstrate that the dissipative approach is immune from the frequency noises with a low noise level. The results show that the detection limit of dissipative sensing has great potential to achieve better performance than that of dispersive sensing for a practical commercial tunable laser scanning system.

Axiomatic design and virtual verification for blackbody cavity sensor

The blackbody cavity sensor for continuous temperature measurement of molten steel has been widely used in steel industry. However, due to the closed bottom of the inner tube, the temperature measurement accuracy is seriously affected. It’s urgent to redesign and improve the sensor, which involves multidisciplinary knowledge, including materials, heat and flow science. This paper first clarifies the relationship between sensor functional requirements and various physical structure parameters from the perspective of axiomatic design. On this basis, the virtual models of the blackbody cavity sensor are established, including geometry model, multi-physical field model, material physical properties and boundary conditions. And then through comparison between experiment and simulation, it is found that for the temperature measurement accuracy, the deviations between the simulation and the actual experimental result are less than 1.5℃. This verifies the accuracy of the virtual model.

Specific Features of the Obtainment of Imide Forming Copolymers of Acrylonitrile and Methacrylic Acid in Concentrated Solutions of N-Substituted Amides

A radical copolymerization of acrylonitrile and methacrylic acid in concentrated solutions of N-substituted amides is studied. The influence of the structure and concentration of amides on the microstructure and properties of copolymers is established. The conditions for the synthesis of copolymers of acrylonitrile and methacrylic acid are determined making it possible to obtain foamed poly(meth)acrylimide with an isotropic structure and high physical and mechanical parameters on their basis.

What we Know about the Composition and Structure of Igapó Forests in the Amazon Basin

The Amazon contains some of the most critical ecosystems on earth and Igapo forests are one of those ecosystems. They are flooded by “black-water”, leached runoff of forest litter. To help in our understanding of igapo forests, and to act as a resource for their future research, I review what we know about their composition and structure. I used my own sampling data to construct floristics tables of the tree species, and tables of physical structural parameters such as tree density, species richness basal area and above-ground biomass (AGB). In addition I used data gotten from literature searches on google scholar, biosys, WorldCat discovery services and other databases for all papers that sampled trees in plots within igapo forests. I found there was a total of 59 families sampled in all the plots. The families with the most genera were Fabaceae and Caesalpiniaceae, with the most species were Fabaceae and Euphorbiaceae, and with the most tree stems were Fabaceae and Euphorbiaceae. The most common genera were Mouriri and Lincania and the most common species were Virola elongate and Swartzia polyphylla. For structure, total stems had a wide range between 167 and 683 per ha, stem sizes generally conformed to a “reverse J” distribution pattern, mean stem sizes were ~20 cm diameter at breast height, there was a species richness range between 90 and 119 per ha, and igapo forests were more open than other forest-types in the Amazon basin. While these plots were in primary igapo forest, my samplings of secondary igapo forests showed they had a reduced structure compared to primary igapo forests but were similar within the different kinds of secondary igapo forests.

Numerical Evaluation and Prediction of Porous Implant Design and Flow Performance.

Porous structure has been widely acknowledged as important factor for mass transfer and tissue regeneration. This study investigates effect of aimed-control design on mass transfer and tissue regeneration of porous implant with regular unit cell. Two shapes of unit cells (Octet truss, and Rhombic dodecahedron) were selected, which have similar symmetrical structure and are commonly used in practice. Through parametric design, porous scaffolds with the strut sizes of φ 0.5, 0.7, 0.9, and 1.1mm were created, respectively. Then using fluid flow simulation method, flow velocity, permeability, and shear stress which could reflect the properties of mass transfer and tissue regeneration were compared and evaluated, and the relationships between porous structure's physical parameters and flow performance were studied. Results demonstrated that unit cell shape and strut size greatly determine and influence other physical parameters and flow performances of porous implant. With the increasing of strut size, pore size and porosity linearly decrease, but the volume, surface area, and specific surface area increased. Importantly, implant with smaller strut size resulted in smaller flow velocity directly but greater permeability and more appropriate shear stress, which should be beneficial to cell attachment and proliferation. This study confirmed that porous implant with different unit cell shows different performances of mass transfer and tissue regeneration, and unit cell shape and strut size play vital roles in the control design. These findings could facilitate the quantitative assessment and optimization of the porous implant.

Advances in Manganese‐Based Oxides Cathodic Electrocatalysts for Li–Air Batteries

AbstractLi–air batteries, characteristic of superhigh theoretical specific energy density, cost‐efficiency, and environment‐friendly merits, have aroused ever‐increasing attention. Nevertheless, relatively low Coulomb efficiency, severe potential hysteresis, and poor rate capability, which mainly result from sluggish oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) kinetics, as well as pitiful cycle stability caused by parasitic reactions, extremely limit their practical applications. Manganese (Mn)‐based oxides and their composites can exhibit high ORR and OER activities, reduce charge/discharge overpotential, and improve the cycling stability when used as cathodic catalyst materials. Herein, energy storage mechanisms for Li–air batteries are summarized, followed by a systematic overview of the progress of manganese‐based oxides (MnO2 with different crystal structures, MnO, MnOOH, Mn2O3, Mn3O4, MnOx, perovskite‐type and spinel‐type manganese oxides, etc.) cathodic materials for Li–air batteries in the recent years. The focus lies on the effects of crystal structure, design strategy, chemical composition, and microscopic physical parameters on ORR and OER activities of various Mn‐based oxides, and even the overall performance of Li–air batteries. Finally, a prospect of the research for Mn‐based oxides cathodic catalysts in the future is made, and some new insights for more reasonable design of Mn‐based oxides electrocatalysts with higher catalytic efficiency are provided.

Kron–Branin modelling of ultra-short pulsed signal microelectrode

An uncommon circuit modelling of microelectrode for ultra-short signal propagation is developed. The proposed model is based on the Tensorial Analysis of Network (TAN) using the Kron–Branin (KB) formalism. The systemic graph topology equivalent to the considered structure problem is established by assuming as unknown variables the branch currents. The TAN mathematical solution is determined after the KB characteristic matrix identification. The TAN can integrate various structure physical parameters. As proof of concept, via hole ended microelectrodes implemented on Kapton substrate were designed, fabricated and tested. The 0.1-MHz-to-6-GHz S-parameter KB model, simulation and measurement are in good agreement. In addition, time-domain analyses with nanosecond duration pulse signals were carried out to predict the microelectrode signal integrity. The modelled microstrip electrode is usually integrated in the atom probe tomography. The proposed unfamiliar KB method is particularly beneficial with respect to the computation speed and adaptability to various structures.

Enhanced radioluminescent nuclear battery by optimizing structural design of the phosphor layer

Radioluminescent nuclear battery is a type of energy conversion device that can be miniaturized, which has the ability to convert nuclear energy into light energy, and again into electrical energy. To explore the response relationship between the phosphor layer structure and the electrical performance of radioluminescent nuclear battery, the physical model was established to research the deposition energy distribution by using Monte Carlo method. The radioluminescence spectra and current-voltage characteristic curves were used to investigate the optical and electrical properties. Through a comprehensive comparison of single plane layer, double plane layer, and V groove layer structures, the simulated results are consistent with experimental results. The results indicate that the Monte Carlo simulation is applicable to analysis of the phosphor layer structure of radioluminescent nuclear battery. Additionally, the results also show that the structure type and physical parameters of the phosphor layer have great influence on the energy deposition. A suitable phosphor layer structure can provide a new route to exhibit higher energy conversion efficiency as well as improving the matching degree between the range of radioactive particles and the thickness of the phosphor layer.

A theoretical study of the influence of barrier thickness variations on optical properties of a semiconductor multiple quantum well slow light device

The influence of barrier thickness variations on the operation of GaAs/AlGaAs multiple quantum well (MQW) slow light devices based on coherence population oscillations (CPOs) is explained. The variations are shown to affect the slow down factor (SDF) and bandwidth of these devices. Bloch equations and the analytical model in fractional dimension are used to analyse and simulate the slow light device. It is shown that other physical parameters of MQW structures (QW width and barrier alloy concentration) affect significantly the optical properties of the device. The presented approaches make it possible to achieve suitable values of SDF and focal energy by adjusting the barrier thickness, QW width and aluminium content. The maximum range of the centre frequency tuning is estimated to be about 1 THz in our calculations, while the slow down factor can reach a high value of 8.5 × 104.

Ultra-Broadband, Lithography-Free, and Large-Scale Compatible Perfect Absorbers: The Optimum Choice of Metal layers in Metal-Insulator Multilayer Stacks

We report ultra-broadband perfect absorbers for visible and near-infrared applications that are based on multilayers of metal-insulator (MI) stacks fabricated employing straightforward layer deposition techniques and are, therefore, lithography-free and large-scale compatible. We scrutinize the impact of different physical parameters of an MIMI absorber structure with analysis of each contributing metal layer. After obtaining the optimal design parameters (i.e. material selection and their thicknesses) with both simulation and numerical analysis (Transfer Matrix Method) methods, an experimental sample is fabricated and characterized. Our fabricated MIMI absorber consists of an optically thick tungsten (W) back reflector layer followed by 80 nm aluminum oxide (Al2O3), 10 nm titanium (Ti), and finally another 80 nm Al2O3. The experimental results demonstrate over 90 percent absorption between 400 nm and 1640 nm wavelengths that is optimized for ultra-broadband absorption in MIMI structures. Moreover, the impedance matching method with free-space is used to shed light on the metallic layer selection process.

Estimating geometrical parameters of cylindrical targets detected by ground-penetrating radar using template matching algorithm

In the current research, the ground-penetrating radar (GPR) method has been employed to identify physical and geometrical parameters of buried cylindrical structures using the pattern recognition approach. To achieve this goal, the well-established mathematical relationships between geometrical parameters of cylindrical target (radius, burial depth, and horizontal location) and the associated GPR hyperbolic response characteristics are employed using the template matching method. In order to validate the applicability of the template matching method in providing estimates of such parameters, the method is first examined on GPR responses of synthetic models with known geometrical parameters followed by applying on real data using two different similarity criteria including 2-D spatial convolution and normalized cross correlation in the wave number domain. In the first step, the GPR responses of 71 synthetic models encompassing one, two, and three horizontal cylinders were produced using the improved 2-D finite difference in frequency domain. Then, appropriate preprocessing sequences to reduce random noise caused by forward modeling were applied on synthetic data. The proposed algorithm applied on several synthetic model responses could estimate the known geometrical parameters of the buried cylinders with acceptable accuracy (maximum error of 15%). The template matching algorithm was also used to extract geometrical parameters of water and wastewater pipes buried in Imam Hossein Square, Isfahan city, as real GPR data. Depending on environmental conditions and subsurface host formation, the real GPR data normally contain a variety of noises; therefore, a series of appropriate objective preprocessing and processing stages were designed in order to apply on real GPR images before deploying template matching algorithm. The applicability of the template matching algorithm on real data and validity of the estimated parameters were proved based on assessing the accuracy of the estimated geometrical parameters of respective pipes through GPR response versus the measured parameters. The proposed algorithm was designed in such a way that all steps of estimating geometrical parameters of buried cylindrical targets are automatically carried out.

Erratum: Water Science and Technology 75 (10), 2257-2267: Liquid-gas mass transfer at drop structures, Natércia Matias, Asbjørn Haaning Nielsen, Jes Vollertsen, Filipa Ferreira and José Saldanha Matos, doi: 10.2166/wst.2017.103.

Over the last decades, considerable progress has been made in the understanding of the sulfur cycle in sewer systems. In spite of a wealth of experimental and field studies that have addressed the release of hydrogen sulfide from free surface flows in gravity sewers and the corresponding air-water mass transfer, little is known about hydrogen sulfide emission under highly turbulent conditions (e.g., drop structures, hydraulic jumps). In this study, experimental work was carried out to analyze the influence of characteristics of drops on reaeration. Physical models were built, mimicking typical sewer drop structures and allowing different types of drops, drop heights, tailwater depths and flow rates. In total, 125 tests were performed. Based on their results, empirical expressions translating the relationship between the mass transfer of oxygen and physical parameters of drop structures were established. Then, by applying the two-film theory with two-reference substances, the relation to hydrogen sulfide release was defined. The experiments confirmed that the choice of the type of drop structure is critical to determine the uptake/emission rates. By quantifying the air-water mass transfer rates between free-fall and backdrop types of drop, the latter resulted in considerably lower oxygen uptake rates.

Liquid-gas mass transfer at drop structures.

Over the last decades, considerable progress has been made in the understanding of the sulfur cycle in sewer systems. In spite of a wealth of experimental and field studies that have addressed the release of hydrogen sulfide from free surface flows in gravity sewers and the corresponding air-water mass transfer, little is known about hydrogen sulfide emission under highly turbulent conditions (e.g., drop structures, hydraulic jumps). In this study, experimental work was carried out to analyze the influence of characteristics of drops on reaeration. Physical models were built, mimicking typical sewer drop structures and allowing different types of drops, drop heights, tailwater depths and flow rates. In total, 125 tests were performed. Based on their results, empirical expressions translating the relationship between the mass transfer of oxygen and physical parameters of drop structures were established. Then, by applying the two-film theory with two-reference substances, the relation to hydrogen sulfide release was defined. The experiments confirmed that the choice of the type of drop structure is critical to determine the uptake/emission rates. By quantifying the air-water mass transfer rates between free-fall and backdrop types of drop, the latter resulted in considerably lower oxygen uptake rates.

Kinetic physical phenomenological model of creep-rupture strength of metals

A kinetic model of creep-rupture strength is constructed using the physicomathematical theory of irreversible strains of metals. An algorithm for the mathematical modeling of the processes occurring during tension of samples is proposed. Results of experimental verification of a uniaxial model of creep-rupture strength are given. It is shown that the proposed model differs from available models in that it contains physical structural parameters (scalar densities of dislocations and microcracks) and kinetic equations for them.

Incorporation of Ag Nanoparticles Into Micelles. Stability Studies of Self-Organized Nanoparticlesmicelles Structures

Abstract In this paper we present the results of measured physical parameters of self-organized structures consisting of hydrophobic functionalized silver nanoparticles and amphiphilic molecules capable of micelles formation. Those systems may be considered as simple models for transfer of nanoparticles through the biological membrane. Three different surfactants were used: negatively charged sodium dodecyl sulphite, SDS, neutral Triton X-100 and positively charged tetredodecyltrimethyl ammonium bromide, TTABr. We have found that hydrophobic functionalized Ag nanoparticles are encapsulated in neutral Triton X-100 micelles with a diameter of 10 nm without significant change in the size of the micelles. The efficiency of encapsulation of Ag by SDS micelles is lower compared to Triron X-100 and no incorporation of Ag nanoparticles into TTABr occurs. Obtained results indicate that in aqueous environment ionic properties of molecules creating micelles and concentration ratios between components determine the efficiency and kinetics of two competitive processes association or aggregation of nanoparticles and encapsulation of Ag nanoparticles within micelles.

Grafting of cellulose acetate with ionic liquids for biofuel purification by a membrane process: Influence of the cation

A new strategy was developed for grafting ionic liquids (ILs) onto cellulose acetate in order to avoid IL extraction and improve its performance for ethyl tert-butyl ether (ETBE) biofuel purification by the pervaporation membrane process. This work extended the scope of IL-containing membranes to the challenging separation of organic liquid mixtures, in which these ILs were soluble. The ILs contained the same bromide anion and different cations with increasing polar feature. The membrane properties were strongly improved by IL grafting. Their analysis in terms of structure-property relationships revealed the influence of the IL content, chemical structure and chemical physical parameters α, β, π* in the Kamlet–Taft polarity scale. The ammonium IL led to the best normalized flux of 0.182kg/m2h for a reference thickness of 5μm, a permeate ethanol content of 100% and an outstanding infinite separation factor for the azeotropic mixture EtOH/ETBE at 50°C.