Physical Parameters Of Structure Research Articles

High-throughput emulsification in a microporous tube-in-tube microchannel device: O/W emulsion formation

Microporous tube-in-tube microchannel (MTMC) emulsification is a continuous high-throughput technique for producing emulsions. The MTMC emulsification device could reach a maximum throughput capacity of 5L/min of emulsion droplets. In this study, the effects of surfactant, phase physical property (viscosity), operation conditions (flow rate, temperature), and structural parameters of the MTMC (micropore size, annular channel width) on average droplet diameter of an O/W emulsion were systemically investigated. The results indicated that soybean oil-in-water (O/W) emulsions could be successfully prepared by using SDS and Tween 80 as surfactants in the MTMC. The formed droplet diameters were almost constant below the critical velocity, over which the droplet diameter drastically increased, and more polydispersed emulsions were formed. The average size of the O/W emulsion droplets decreased with the reduction of surfactant concentration, temperature, viscosity of the dispersed phase, micropore size and annular channel width, as well as the increase of overall flow rate. Furthermore, the characteristics of the emulsification pressure drop through the MTMC were also explored.

Development of physical-parameter identification procedure for in-situ buildings with sliding-type isolation system

A system identification procedure is developed to identify the physical parameters of structures with seismic isolation using the friction pendulum systems (FPSs). The superstructure is assumed to be linear on account of substantial reduction of seismic forces with the installation of FPS. Hysteretic models of both Coulomb's and Mokha's friction mechanism have been considered for the FPS. Simulation results indicate that the physical parameters of the FPS and superstructure can be successfully identified by the proposed scheme. Experimental verification has been conducted further via shaking table tests using realistic earthquake scenarios. The identified parameters from seismic response data indicate that the FPSs behave in better agreement with Mokha's friction mechanism than Coulomb's. Feasibility of the proposed scheme in the identification of FPS-isolated structures using seismic data has been verified. This may facilitate in-situ performance assessment of structures isolated with sliding-type isolation systems.

Lanthanum salts improve bone formation in a small animal model of post-menopausal osteoporosis

Two different lanthanum salts, lanthanum carbonate (LaCO(3)) and Lancer(®), a lanthanide citrate mixture, were tested for their effects on bone metabolism in a small animal model for post-menopausal osteoporosis. Forty female outbred Wistar Han rats, sham-operated (SHAM, positive control, n = 10) or ovariectomized (OVX, n = 30) at 4 months of age, were allotted into following groups (n = 10/group): (i) SHAM, (ii) OVX control (negative control), (iii) OVX + LaCO(3) (1.74 g/kg feed) and (iv) OVX + Lancer(®) (8 g/kg feed). Effects on bone were investigated by bone markers [osteocalcin (Oc) in serum and excretion of pyridinoline (PYD) in urine] and by physical parameters of bone structure and bone composition (bone mass, calcium, phosphorus and magnesium content in bone crude ash). Bone micro-architecture and bone mineral density were evaluated by peripheral quantitative computed tomography and micro-computed tomography (μCT). The animal model could be validated by differences between OVX control and SHAM. Body mass and feed intake were the same among the four groups. Oc was clearly increased in the two experimental groups (p < 0.001) vs. SHAM and OVX control. Bone mass and calcium content in bone ash were significantly higher than in OVX control. The Ca/P ratio in bone ash of the two lanthanide groups did not differ from SHAM. Bone-protecting effects of lanthanides were clearly demonstrated by an increased trabecular density which is the region of interest for osteoporotic bone loss. A 3D imaging of bone micro-architecture by μCT visualized descriptively the positive effects of lanthanides on bone formation. The results of this study demonstrate an improvement of bone formation and bone-protecting effects of lanthanides in the OVX rat. Thus, lanthanum salts suggest a prevention of post-menopausal bone loss and may be of benefit in experimental osteopenia following ovariectomy.

The influence of mechanical cold drawing and drawing velocity on the molecular structure of isotactic polypropylene fiber

AbstractThe main goal of this work study is to study the influence of mechanical cold drawing and drawing velocity on the molecular orientation and physical structure parameters of isotactic polypropylene, iPP, fibers. A Video Opto‐ Mechanical device (VOM) attached with automatic multiple‐beam interferometric technique was used to cold draw iPP fibers at different draw ratio and drawing velocity. The molecular structure of iPP fiber was characterized by measuring the refractive indices, birefringence, optical orientation function, orientation angle, the percentage of the volume fraction of amorphous and crystalline regions, density and the mean square density fluctuation. The obtained microinterferograms of multiple beam interference fringes were enhanced and the noises were removed by using Fourier transform method. The obtained contour lines were analyzed via a software program for fiber refractive index determination. The results show that the drawing velocity has a less effect than the draw ratio on the molecular structure of iPP fiber. The contour lines of microinterferograms are given for illustration. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Zooplankton in the zones of confluence of unregulated rivers

The hydrophysical characteristics and indices of zooplankton are given for the confluence zones of small and medium tributaries and channels of the Don and Khoper rivers within the territory of Voronezh oblast. Three types of confluence areas of tributaries and recipient rivers are described. In these areas the water masses mix and habitats differing in physical parameters of water and structures of aquatic animal communities are formed.

Tribological evaluation of sportswear with negative fit worn next to skin

Compression garments are constructed to have a negative fit where the size of the garment is smaller than that of the body over which they are fitted. Due to this negative fit, these types of garments generate pressure on the underlying tissue of the human body where the inner surface of these garments is in full contact with the wearer’s skin. Sensorial or tactile comfort is an important part of an overall physiological comfort of sport apparel. The friction between fabric and skin and the fabric surface roughness are two important components in evaluation of the sensorial comfort of fabrics and materials. The objective of this study is to investigate and compare the material surface characteristics of fabrics suitable for the sport compression garments under conditions similar to those when such garments are worn. The study quantitatively examines and evaluates the effects of fabric construction, physical structural parameters and especially fabric elastic deformation on the fabric surface topography as relevant to the practical wear of sport garments with negative fit made from it. In addition, the influence of the presence of moisture in the fabrics due to the sweat absorption during strenuous physical activity on the textile surface characteristics is addressed.

Methionine–pyrene hybrid based fluorescent probe for trace level detection and estimation of Hg(II) in aqueous environmental samples: Experimental and computational studies

A new fluorescent, Hg2+ selective chemosensor, 4-methylsulfanyl-2-[(pyren-4-ylmethylene)-amino] butyric acid methyl ester (L, MP) was synthesized by blending methionine with pyrene. It was well characterized by different analytical techniques, viz. 1H NMR, 13C NMR, QTOF mass spectra, elemental analysis, FTIR and UV–vis spectroscopy. The reaction of this ligand with Hg2+ was studied by steady state and time-resolved fluorescence spectroscopy. The Hg2+ complexation process was confirmed by comparing FTIR, UV–vis, thermal, QTOF mass spectra and 1H NMR data of the product with that of the free ligand values. The composition (Hg2+:L=1:1) of the Hg2+ complex in solution was evaluated by fluorescence titration method. Based on the chelation assisted fluorescence quenching, a highly sensitive spectrofluorometric method was developed for the determination of trace amounts of Hg2+ in water. The ligand had an excitation and emission maxima at 360nm and 455nm, respectively. The fluorescence life times of the ligand and its Hg2+ complex were 1.54ns and 0.72ns respectively. The binding constant of the ligand, L with Hg2+ was calculated using Benesi–Hildebrand equation and was found to be 7.5630×104. The linear range of the method was from 0 to 16μgL−1 with a detection limit of 0.056μgL−1 for Hg2+. The quantum yields of the ligand and its Hg2+ complex were found to be 0.1206 and 0.0757 respectively. Both the ligand and its Hg2+ complex have been studied computationally (Ab-initio, Hartree Fock method) to get their optimized structure and other related physical parameters, including bond lengths, bond angles, dipole moments, orbital interactions etc. The binding sites of the ligand to the Hg2+ ion as obtained from the theoretical calculations were well supported by 1H NMR titration. The interference of foreign ions was negligible. This method has been successfully applied to the determination of mercury(II) in industrial waste water.

A probabilistic damage identification approach for structures with uncertainties under unknown input

To avoid the false positives of damages in the deterministic identification method induced by uncertainties in measurement noise, a probabilistic method is proposed to identify damages of the structures with uncertainties under unknown input. The proposed probabilistic method is developed from a deterministic simultaneous identification method of structural physical parameters and input based on dynamic response sensitivity. The deterministic simultaneous identification method is first derived. The effect of uncertainties caused by measurement noise on the identified parameters is then investigated. The statistical parameters of the identified structural parameters are calculated. The damage index is derived from the statistical parameters of the physical parameters of intact and damaged structure. The probability of identified damage, defined as the probability of identified structural stiffness smaller than that of intact structure, is further derived using the probability method. A twelve-story building and a nine-bay three-dimensional frame structure are, respectively, analyzed numerically and experimentally using the proposed method. The research results indicate that the probabilistic simultaneous identification method for damage and input can decrease the false positives of damages in contrast with the deterministic method under intensive measurement noise, and it can also achieve an accurate identification for structural unknown input.

Structural Parameter Identification Based on Equivalent Single Degree Systems

In order to solve the problems of optimization algorithm used to identify the physical parameters of structures, a new method based on a series of equivalent single degree systems is proposed in this paper. The key idea of the method is that a multi-degree system can be represented by a series of single degree systems that can be identified one by one to perform the identification of the whole system. This method can not only decrease the dimensions of optimization algorithm, but also reduce the amount of estimation work in searching for the bound of parameters, and at the same time improve the identification results when parameters might suddenly change. In the numerical simulation of the physical parameter identification of a multi-degree system, Differential evolution is one of the optimization algorithm methods which are used to identify a series of equivalent single degree systems instead of the multi-degree system they represent, and the identification results prove that the method proposed in this paper is valid.

A Sensitivity Study of Grain Growth Model For Prediction of ECT and CET Transformations in Continuous Casting of Steel

A two dimensional model was developed to predict the grain structure (Equiaxed to Columnar Transformation (ECT) and Columnar to Equiaxed Transformation (CET) in the continuous casting of steel. The processes of nucleation, growth and impingement of the grains are modelled as follows: (I) the nucleation is modeled through a continuous dependency of the nucleation density on temperature by the Gaussian distribution. Different nucleation parameters are used at the boundary and in the bulk region. (II) The growth and impingement are modeled by the Kurz, Giovanola, Trivedi (KGT) model. The Cellular Automata (CA) technique is used to solve the model. The CA method is based on the Nastac’s and simplified neighborhoods. Calculations are shown for square billets of the dimension 140 mm. Fixed input parameter of the model represents the macroscopic temperature field obtained from the Štore Steel billet simulation system [1]. All other grain structure physical model parameters are varied, such as: the surface and the bulk area, mean nucleation undercooling, standard deviation of undercooling, maximum density of nuclei. The computational parameters, such as the micro mesh size and the time step are varied as well. The influence of the variation of different parameters on calculated grain structure is shown. Finally, the model parameters are adjusted in order to obtain the experimentally determined actual billet ECT and CET positions for 51CrV4+Mo spring steel (Al: 0.02, Cr: 1.05, Cu: 0.125, Mn: 0.9,Mo: 0.025, Ni: 0.1, Si: 0.275, V: 0.155, C: 0.51, P: 0.0125, S: 0.0275 wt%). A systematic procedure is outlined for adjusting of the model data with the experiment.

Utilização de cinza de casca de arroz na remoção de cromo hexavalente

The growing concerns for treating effluents oblige the industries for searching low cost adsorbents. As a result of that, the present work is justified, which has the aim of evaluate the potentiality of rice husk ash (RHA) in the adsorption of hexavalent chromium. The RHA was obtained from the burning process of rice husk to generate energy. Ash samples were grinded and characterized through physical, chemical and micro structural parameters. The adsorption tests were carried out using standard solution of Cr (VI) with 25 ppm of initial concentration. The analyzed variables were: adsorbent granulometry; pH and contact time. The quantification of Cr (VI) was carried out via colorimetric method of 1.5-diphenilcarbazide. During the tests it was observed that the removal rate of Cr (VI) varied from 25 to 84%. These results demonstrated the potentiality of RHA application in the adsorption of Cr (VI) when the process parameters are well adjusted. Key words: rice husk ash, adsorption, Chromium (VI).

A Dynamic Life Evolution Method Based On Timedependent Reliability By Health Monitoring Data

Abstract This paper aims at the disadvantage of traditional calculation mode of reliability and proposes a new idea to calculate resistance of structure. This idea uses identification of structure modal parameters, structure physical parameters and EWMA control map. Reliability by load effects taken and life prediction can be achieved. In addition, by utilization of high order statistical predicting function for life prediction, meanwhile, modification of dynamic evolution in reliability calculation and life prediction are completed.

Structural Health Monitoring Using High-Frequency Electromechanical Impedance Signatures

An overview of recent advances in electromechanical impedance- (EMI-) based structural health monitoring is presented in this paper. The basic principle of the EMI method is to use high-frequency excitation to sense the local area of a structure. Changes in impedance indicate changes in the structure, which in turn indicate that damages appear. An accurate EMI model based on the method of reverberation-ray matrix is introduced to correlate changes in the signatures to physical parameters of structures for damage detection. Comparison with other numerical results and experimental data validates the present model. A brief remark of the feasibility of implementing the EMI method is considered and the effects of some physical parameters on EMI technique are also discussed.

Statistical Theory of Plasmas Turbulence

We present a statistical theory of intermittency in plasma turbulence based on short-lived coherent structures (instantons). In general, the probability density functions (PDFs) of the flux R are shown to have an exponential scaling P(R) ∝ exp (-cRs ) in the tails. In ion-temperature-gradient turbulence, the exponent takes the value s = 3/2 for momentum flux and s = 3 for zonal flow formation. The value of s follows from the order of the highest nonlinear interaction term and the moments for which the PDFs are computed. The constant c depends on the spatial profile of the coherent structure and other physical parameters in the model. Our theory provides a powerful mechanism for ubiquitous exponential scalings of PDFs, often observed in various tokamaks. Implications of the results, in particular, on structure formation are further discussed.

Designing Structural Parameters of Nonwovens

In this paper, a computer aided system for designing nonwoven materials is presented. As an original approach in the field of nonwoven research, both quality measurement analysis and human knowledge processing are integrated in the system. It allows designers to optimize the structure of nonwoven materials with limited trials according to the functional properties given in customers' specifications. This system aims at modeling the relation between functional or physical properties (outputs) and structural parameters (inputs) of nonwoven products. In order to reduce the complexity of the system, a procedure is proposed for selecting the most relevant input variables based on a ranking criterion, which takes into account both the expertise of manufacturers and the measured data. In this criterion, fuzzy logic is used to establish a good compromise or a fusion between these two uncertain and incomplete information sources. Then, two models are set up by utilizing multilayer feed forward neural networks, whi...

Identification of linear handling models for road vehicles

This study reports the identification of linear handling models for road vehicles starting from structural identifiability analysis, continuing with the experiments to acquire data on a vehicle equipped with a sensor set and data acquisition system, and ending with the estimation of parameters using the collected data. The model structure originates from the well-known linear bicycle model that is frequently used in handling analysis of road vehicles. Physical parameters of the bicycle model structure are selected as the unknown parameter set that is to be identified. Global identifiability of the model structure is analysed, in detail, and concluded according to various available sensor sets. Physical parameters of the bicycle model structure are estimated using prediction error estimation method. Genetic algorithms are used in the optimisation phase of the identification algorithm to overcome the difficulty in the selection of initial values for parameter estimates. Validation analysis of the identified model is also presented. The identified model is shown to track the system response successfully.

Designing Structural Parameters of Nonwovens Using Fuzzy Logic and Neural Networks

In this paper, a computer aided system for designing nonwoven materials is presented. As an original approach in the field of nonwoven research, both quality measurement analysis and human knowledge processing are integrated in the system. It allows designers to optimize the structure of nonwoven materials with limited trials according to the functional properties given in customers’ specifications. This system aims at modeling the relation between functional or physical properties (outputs) and structural parameters (inputs) of nonwoven products. In order to reduce the complexity of the system, a procedure is proposed for selecting the most relevant input variables based on a ranking criterion, which takes into account both the expertise of manufacturers and the measured data. In this criterion, fuzzy logic is used to establish a good compromise or a fusion between these two uncertain and incomplete information sources. Then, two models are set up by utilizing multilayer feed forward neural networks, which take into account the generality and the specificity of the product families respectively. The presented models have been validated with the use of experimental data concerning several families of nonwoven products.

Numerical studies of a non-linear aeroelastic system with plunging and pitching freeplays in supersonic/hypersonic regimes

The flutter and post flutter of a two-dimensional double-wedge lifting surface with combined freeplay and cubic stiffness nonlinearities in both plunging and pitching degrees-of-freedom operating in supersonic/hypersonic flight speed regimes have been analyzed. In addition to the structural nonlinearities, the third-order piston theory aerodynamics is used to evaluate the unsteady non-linear aerodynamic force and moment. Such model accounts for stiffness and damping contributions produced by the aerodynamic loads. Responses involving limit cycle oscillation and chaotic motion are observed over a large number of parameters that characterizes the aeroelastic system. Results of the present study show that the freeplay in the pitching degree-of-freedom and soft/hard cubic stiffness in the pitching and plunging degrees-of-freedom have significant effects on the LCOs exhibited by the aeroelastic system in the supersonic/hypersonic flight speed regimes. The simulations also show that the aeroelastic system behavior is greatly affected by physical structural parameters, such as the radius of gyration and the frequency ratio, especially in post-flutter regimes, when accounting for all system nonlinearities. It has been shown that at high Mach numbers the non-linear aerodynamic stiffness yields detrimental effects from the aeroelastic point of view, while the damping one do not.

Stream Buffer Effectiveness in an Agriculturally Influenced Area, Southwestern Georgia

To determine useful metrics for assessing stream water quality in the Southeastern Coastal Plain, we examined differences among two buffered and three unbuffered streams in an agricultural landscape in southwestern Georgia. Potential indicators included amphibian diversity and abundance, aquatic macroinvertebrate populations, riparian vegetative structure, water quality, and stream physical parameters. Variability among sites and treatments (buffered vs. unbuffered) existed, with sites in the same treatment as most similar, and disturbances from a nearby eroding gully strongly affecting one unbuffered site. Of the invertebrate metrics examined, percentages of clingers, Ephemeroptera-Plecoptera-Trichoptera (EPT), Elmidae (Coleoptera), Crustacea (Decapoda and Amphipoda), and dipterans were found to be possible indicators of stream health for perennial streams within this region. Overall, buffered sites showed higher percentages of sensitive invertebrate groups and showed lower and more stable concentrations of nitrate N, suspended solids, and fecal coliforms (FCs). Percent canopy cover was similar among sites; however, riparian vegetative coverage and percent leaf litter were greatest at buffered sites. No differences in amphibian abundance, presence, and absence within the riparian area were apparent between sites; however, instream larval salamanders were more abundant at buffered streams. In this study, stream buffers appeared to decrease nutrient and sediment loads to adjacent streams, enhancing overall water quality. Selected benthic macroinvertebrate metrics and amphibian abundance also appeared sensitive to agricultural influences. Amphibians show potential as indicator candidates, however further information is needed on their responses and tolerances to disturbances from the microhabitat to landscape levels.

Application of an optimization methodology for multidisciplinary system design of microgyroscopes

Microgyroscopes integrated with micro-transducers, readout and control circuits in a common board normally form complex microsystems. Optimization of the design of such systems requires thorough understanding of the coupling effects of their working environments, their physical structural parameters, their construction of electronics, and their fabrication processes, etc. prior to any design verification by costly and time-consuming prototyping. A tuning fork gyroscope was taken as an example to demonstrate the principle for optimizing the necessary multidisciplinary design procedures in designing MEMS, typically including: the environmental quality factors, structural properties, readout circuits, and fabrication factors. It then used genetic algorithm (GA) to optimize the global sensitivity by a specifically designed searching methodology. The so obtained optimal results were further verified by a FEM modal analysis and by an experiment with an acceptable resolution.