Ident 1D - a novel software tool for an easy identification of material constitutive parameters

International Nuclear Information System (INIS)

Le Ber, L.; Cotoni, V.; Nicola, L.; Sainte Catherine, C.

1998-01-01

Non-linear finite element computations make use of very sophisticated constitutive equations for description of materials behaviour. The first difficulty encountered by potential users is the gap existing between raw material characterisation on uniaxial specimens and the knowledge of the required equation's parameters. There are very few software for this particular task. IDENT 1D is a special software developed under Matlab language in our laboratory, which is able to provide a complete optimised parameters set for implemented models. The originality of IDENT 1D is that no initial estimation of the material parameters is requested of the user. Two main examples are described in this article: the Lemaitre and Chaboche creep law coupled with damage and a non unified cyclic law proposed by Contesti and Cailletaud with a separation of plastic and viscous strain terms which is called DDI model. For both laws, the identification method is completely described. Each method is then applied to a set of experimental data. In both cases, the results of the parameters identification show a very good agreement with experimental data. (authors)

Morphological Parameters in Relation to the Electromagnetic Properties of Microcellular Thermoplastic Polyurethane Foam in X-Band Frequency Ranges

Directory of Open Access Journals (Sweden)

Mohammad Hassan Moeini

2017-04-01

Full Text Available Microcellular thermoplastic polyurethane foams are examined as absorbing materials in the X-band (8.2-12.4 GHz frequency range by means of experiment. In this work, we aim to establish relationships between foam morphology including cell size and air volume fraction and electromagnetic properties including absorption, transmission and reflection quality. Nanocomposites based on thermoplastic polyurethane containing carbon black were prepared by coagulation method. In this procedure 15 wt% carbon black-containing nanocomposite was converted to microcellular foams using batch foaming process and supercritical carbon dioxide as physical foaming agent. The morphology of the foams was evaluated by scanning electron microscopy. S-parameters of the samples were measured by a vector network analyzer (VNA and the effect of morphological parameters such as cell size and air volume fraction on the absorbing properties was investigated. We also established structure/properties relationships which were essential for further optimizations of the materials used in the construction of radar absorbing composites. Foaming reduced the percolation threshold of the nanocomposites due to the reduction in the average distance between nanoparticles. Foaming and dielectric constant reduction dropped the reflection percentage significantly. The increase in air volume fraction in the foam increased absorption per its weight, because of multiple scattering in composite media. The sensitivity of electromagnetic wave toward the variation of cell size is strongly weaker than that toward the variation of air volume fraction. Electromagnetic properties of the microcellular foams deviated a little from effective medium theories (EMTs. Air volume fraction of the cells was a function of cell size and smaller cells showed higher absorption.

Evaluation of diffusion parameters of radon in porous material by flow-through diffusion experiment

International Nuclear Information System (INIS)

Chunnan Hsu; Shihchin Tsai; Shihming Liang

1994-01-01

The effectiveness of a material in reducing the fluence rate of Rn from soil was assessed in this study by using a flow-through diffusion experiment to evaluate the diffusion parameters -apparent diffusion coefficient and capacity factor - of radon (Rn) in a porous material. An improved method based on the nonlinear least-squares and Marquardt's method (NLSM method) was proposed to provide more reliable analyses of experimental data than the graphical method. The NLSM method was confirmed by the experimental results to be capable of estimating the diffusion parameters, even if the process was transient. This method was also demonstrated to correlate sufficiently with the results by the conventional method while the process had already reached steady-state. Natural mordenite was employed in this study as a testing material because it has more effective sorption for noble gas than any other earthen material. (author)

Moderating ratio parameter evaluation for different materials by means of Monte Carlo calculations and reactivity direct measurements

International Nuclear Information System (INIS)

Borio, A.; Cagnazzo, M.; Marchetti, F.; Pappalardo, P.; Salvini, A.

2004-01-01

The aim of this work is to determine moderating properties of different materials (water, graphite, perfluoropolyethers), in particular the slowing down power (SDP) and the moderating ratio (MR), defined as SDP =ξΣ S and MR=ξΣ S /Σ A , where Σ S and Σ A represent the macroscopic scattering and absorption cross section, respectively, and ξ is the average logarithmic energy loss per collision. Slowing-down power indicates how rapidly a neutron will slow down in the material, but it does not fully explain the effectiveness of the material as a moderator. In fact, a material can slow down neutrons with high efficiency because of its big Σ S , but it can be a poor moderator because with high probability it also absorbs neutrons. Thus, the most complete measure of the effectiveness of a moderator is the moderating ratio parameter which takes into account also the absorption effects: the bigger is the moderating ratio values, the more effectively the material performs as a moderator. The first part of the work consisted in the comparison between the SDP and MR parameter evaluated for different materials by means of Monte Carlo simulations and by means of calculations based on their definition formula (they are developed from knowledge of material composition and of microscopic cross section σ i (derived from literature)). It was found that this comparison showed a good agreement with errors less than 10 %. Thus the Monte Carlo code seems to be a good support for the calculation of the moderating parameters, particularly useful when the materials are compounds of many elements. The second part of the work was dedicated to correlate the materials' MR values with the measured variation of reactivity induced by the insertion of the materials in the core of TRIGA Mark II reactor of the University of Pavia. This is possible by definition of a new parameter for the measure. This parameter, named S, depends on the total weight of the sample inserted in the reactor core

Parameters Influence of CO2 Laser on Cutting Quality of Polymer Materials

OpenAIRE

Robert Cep; Sarka Malotova; Marek Pagac; Marek Sadilek; Jiri Lichovnik

2016-01-01

The article deals with evaluating of the resulting surface state of the three plastic materials and identification of suitable conditions for laser cutting with CO2 tube. As representative were chosen polypropylene, polymethylmethacrylate and polyamide. When cutting these types of materials it could melt eventually their re-sintering. A suitable combination of parameters is possible to achieve of sufficient quality of the cut. The samples were cut at different feed speed and laser power. Then...

Scintillator-CCD camera system light output response to dosimetry parameters for proton beam range measurement

Energy Technology Data Exchange (ETDEWEB)

Daftari, Inder K., E-mail: idaftari@radonc.ucsf.edu [Department of Radiation Oncology, 1600 Divisadero Street, Suite H1031, University of California-San Francisco, San Francisco, CA 94143 (United States); Castaneda, Carlos M.; Essert, Timothy [Crocker Nuclear Laboratory,1 Shields Avenue, University of California-Davis, Davis, CA 95616 (United States); Phillips, Theodore L.; Mishra, Kavita K. [Department of Radiation Oncology, 1600 Divisadero Street, Suite H1031, University of California-San Francisco, San Francisco, CA 94143 (United States)

2012-09-11

The purpose of this study is to investigate the luminescence light output response in a plastic scintillator irradiated by a 67.5 MeV proton beam using various dosimetry parameters. The relationship of the visible scintillator light with the beam current or dose rate, aperture size and the thickness of water in the water-column was studied. The images captured on a CCD camera system were used to determine optimal dosimetry parameters for measuring the range of a clinical proton beam. The method was developed as a simple quality assurance tool to measure the range of the proton beam and compare it to (a) measurements using two segmented ionization chambers and water column between them, and (b) with an ionization chamber (IC-18) measurements in water. We used a block of plastic scintillator that measured 5 Multiplication-Sign 5 Multiplication-Sign 5 cm{sup 3} to record visible light generated by a 67.5 MeV proton beam. A high-definition digital video camera Moticam 2300 connected to a PC via USB 2.0 communication channel was used to record images of scintillation luminescence. The brightness of the visible light was measured while changing beam current and aperture size. The results were analyzed to obtain the range and were compared with the Bragg peak measurements with an ionization chamber. The luminescence light from the scintillator increased linearly with the increase of proton beam current. The light output also increased linearly with aperture size. The relationship between the proton range in the scintillator and the thickness of the water column showed good linearity with a precision of 0.33 mm (SD) in proton range measurement. For the 67.5 MeV proton beam utilized, the optimal parameters for scintillator light output response were found to be 15 nA (16 Gy/min) and an aperture size of 15 mm with image integration time of 100 ms. The Bragg peak depth brightness distribution was compared with the depth dose distribution from ionization chamber measurements

Positron range in tissue-equivalent materials: experimental microPET studies

Science.gov (United States)

Alva-Sánchez, H.; Quintana-Bautista, C.; Martínez-Dávalos, A.; Ávila-Rodríguez, M. A.; Rodríguez-Villafuerte, M.

2016-09-01

In this work an experimental investigation was carried out to study the effect that positron range has over positron emission tomography (PET) scans through measurements of the line spread function (LSF) in tissue-equivalent materials. Line-sources consisted of thin capillary tubes filled with 18F, 13N or 68Ga water-solution inserted along the axis of symmetry of cylindrical phantoms constructed with the tissue-equivalent materials: lung (inhale and exhale), adipose tissue, solid water, trabecular and cortical bone. PET scans were performed with a commercial small-animal PET scanner and image reconstruction was carried out with filtered-backprojection. Line-source distributions were analyzed using radial profiles taken on axial slices from which the spatial resolution was determined through the full-width at half-maximum, tenth-maximum, twentieth-maximum and fiftieth-maximum. A double-Gaussian model of the LSFs was used to fit experimental data which can be incorporated into iterative reconstruction methods. In addition, the maximum activity concentration in the line-sources was determined from reconstructed images and compared to the known values for each case. The experimental data indicates that positron range in different materials has a strong effect on both spatial resolution and activity concentration quantification in PET scans. Consequently, extra care should be taken when computing standard-uptake values in PET scans, in particular when the radiopharmaceutical is taken up by different tissues in the body, and more even so with high-energy positron emitters.

Sensitivity of corneal biomechanical and optical behavior to material parameters using design of experiments method.

Science.gov (United States)

Xu, Mengchen; Lerner, Amy L; Funkenbusch, Paul D; Richhariya, Ashutosh; Yoon, Geunyoung

2018-02-01

The optical performance of the human cornea under intraocular pressure (IOP) is the result of complex material properties and their interactions. The measurement of the numerous material parameters that define this material behavior may be key in the refinement of patient-specific models. The goal of this study was to investigate the relative contribution of these parameters to the biomechanical and optical responses of human cornea predicted by a widely accepted anisotropic hyperelastic finite element model, with regional variations in the alignment of fibers. Design of experiments methods were used to quantify the relative importance of material properties including matrix stiffness, fiber stiffness, fiber nonlinearity and fiber dispersion under physiological IOP. Our sensitivity results showed that corneal apical displacement was influenced nearly evenly by matrix stiffness, fiber stiffness and nonlinearity. However, the variations in corneal optical aberrations (refractive power and spherical aberration) were primarily dependent on the value of the matrix stiffness. The optical aberrations predicted by variations in this material parameter were sufficiently large to predict clinically important changes in retinal image quality. Therefore, well-characterized individual variations in matrix stiffness could be critical in cornea modeling in order to reliably predict optical behavior under different IOPs or after corneal surgery.

Spectroscopic Parameters of Lumbar Intervertebral Disc Material

Science.gov (United States)

Terbetas, G.; Kozlovskaja, A.; Varanius, D.; Graziene, V.; Vaitkus, J.; Vaitkuviene, A.

2009-06-01

There are numerous methods of investigating intervertebral disc. Visualization methods are widely used in clinical practice. Histological, imunohistochemical and biochemical methods are more used in scientific research. We propose that a new spectroscopic investigation would be useful in determining intervertebral disc material, especially when no histological specimens are available. Purpose: to determine spectroscopic parameters of intervertebral disc material; to determine emission spectra common for all intervertebral discs; to create a background for further spectroscopic investigation where no histological specimen will be available. Material and Methods: 20 patients, 68 frozen sections of 20 μm thickness from operatively removed intervertebral disc hernia were excited by Nd:YAG microlaser STA-01-TH third harmonic 355 nm light throw 0, 1 mm fiber. Spectrophotometer OceanOptics USB2000 was used for spectra collection. Mathematical analysis of spectra was performed by ORIGIN multiple Gaussian peaks analysis. Results: In each specimen of disc hernia were found distinct maximal spectral peaks of 4 types supporting the histological evaluation of mixture content of the hernia. Fluorescence in the spectral regions 370-700 nm was detected in the disc hernias. The main spectral component was at 494 nm and the contribution of the components with the peak wavelength values at 388 nm, 412 nm and 435±5 nm were varying in the different groups of samples. In comparison to average spectrum of all cases, there are 4 groups of different spectral signatures in the region 400-500 nm in the patient groups, supporting a clinical data on different clinical features of the patients. Discussion and Conclusion: besides the classical open discectomy, new minimally invasive techniques of treating intervertebral disc emerge (PLDD). Intervertebral disc in these techniques is assessed by needle, no histological specimen is taken. Spectroscopic investigation via fiber optics through the

Scattering-parameter extraction and calibration techniques for RF free-space material characterization

DEFF Research Database (Denmark)

Kaniecki, M.; Saenz, E.; Rolo, L.

2014-01-01

This paper demonstrates a method for material characterization (permittivity, permeability, loss tangent) based on the scattering parameters. The performance of the extraction algorithm will be shown for modelled and measured data. The measurements were carried out at the European Space Agency...

Materials Sciences Division long range plan

International Nuclear Information System (INIS)

1984-12-01

The intent of this document is to provide a framework for programmatic guidance into the future for Materials Sciences. The Materials Sciences program is the basic research program for materials in the Department of Energy. It includes a wide variety of activities associated with the sciences related to materials. It also includes the support for developing, constructing, and operating major facilities which are used extensively but not exclusively by the materials sciences

A comparative study of parameters used in design and operation of desalination experimental facility versus the process parameters in a commercial desalination plant

International Nuclear Information System (INIS)

Hanra, M.S.; Verma, R.K.; Ramani, M.P.S.

1982-01-01

Desalination Experimental Facility (DEF) based on multistage flash desalination process has been set up by the Desalination Division of the Bhabha Atomic Research Centre, Bombay. The design parameters of DEF and materials used for various equipment and parts of DEF are mentioned. DEF was operated for 2300 hours in six operational runs. The range of operational parameters maintained during operation and observations on the performance of the materials of construction are given. Detailed comparison has been made for the orocess parameters in DEF and those in a large size plant. (M.G.B.)

Effect of initial material on the electrolytic parameters of field-effect transistors

International Nuclear Information System (INIS)

Antonov, A.V.; Sinitsyn, V.N.; Fursov, V.V.

1978-01-01

The effect of initial material parameters upon the main electric characteristics of field transistors at room and optimum (170 deg C) temperatures is studied. For that purpose, the values of parasitic resistances rsub(s), specific resistances rho and steepness S of field transistors, depending on temperature and electrical conditions were measured. The output volt-ampere characteristics of the transistors at room and optimum temperatures are given. An analysis of the results obtained permits to conclude that there is an unambiguous relationship between rho and rsub(s). Impact ionization is shown to occur for field transistors with lower rho at lower drain voltage. When manufacturing field transistors designed for operation at low temperatures, one should remember that a minimum rho may restrict maximum possible steepness. When designing field transistors with optimum noise characteristics, one should variate not only such material parameters as mobility and carrier density, but also select optimum geometry

Calculations on displacement damage and its related parameters for heavy ion bombardment in reactor materials

International Nuclear Information System (INIS)

Sone, Kazuho; Shiraishi, Kensuke

1975-04-01

The depth distribution of displacement damage expressed in displacements per atom (DPA) in reactor materials such as Mo, Nb, V, Fe and Ni bombarded by energetic nitrogen, argon and self ions with incident energy below 2 MeV was calculated following the theory developed by Lindhard and co-workers for the partition of energy as an energetic ion slowing down. In this calculation, energy loss due to electron excitation was taken into account for the atomic collision cascade after the primary knock-on process. Some parameters indispensable for the calculation such as energy loss rate, damage efficiency, projected range and its straggling were tabulated as a function of incident ion energy of 20 keV to 2 MeV. The damage and parameters were also calculated for 2 MeV nickel ions bombarding Fe targets. In this case, the DPA value is of 40--75% overestimated in a calculation disregarding electronic energy loss for primary knock-on atoms. The formula proposed in this report is significant for calculations on displacement damage produced by heavy ion bombardment as a simulation of high fluence fast neutron damage. (auth.)

Calculations on displacement damage and its related parameters for heavy ion bombardment in reactor materials

Energy Technology Data Exchange (ETDEWEB)

Sone, K; Shiraishi, K

1975-04-01

The depth distribution of displacement damage expressed in displacements per atom (DPA) in reactor materials such as Mo, Nb, V, Fe and Ni bombarded by energetic nitrogen, argon and self ions with incident energy below 2 MeV was calculated following the theory developed by Lindhard and co-workers for the partition of energy as an energetic ion slowing down. In this calculation, energy loss due to electron excitation was taken into account for the atomic collision cascade after the primary knock-on process. Some parameters indispensable for the calculation such as energy loss rate, damage efficiency, projected range and its straggling were tabulated as a function of incident ion energy of 20 keV to 2 MeV. The damage and parameters were also calculated for 2 MeV nickel ions bombarding Fe targets. In this case, the DPA value is of 40--75% overestimated in a calculation disregarding electronic energy loss for primary knock-on atoms. The formula proposed in this report is significant for calculations on displacement damage produced by heavy ion bombardment as a simulation of high fluence fast neutron damage.

EXAFS, Determination of Short Range Order and Local Structures in Materials

NARCIS (Netherlands)

Koningsberger, D.C.; Prins, R.

1981-01-01

Extended X-ray Absorption Fine Structure (EXAFS) is a powerful method of determining short range order and local structures in materials using X-ray photons produced by a synchrotron light source, or in-house by a high intensity rotating anode X-ray generator. The technique has provided valuable

Sparkle/PM7 Lanthanide Parameters for the Modeling of Complexes and Materials

OpenAIRE

Dutra, José Diogo L.; Filho, Manoel A. M.; Rocha, Gerd B.; Freire, Ricardo O.; Simas, Alfredo M.; Stewart, James J. P.

2013-01-01

The recently published Parametric Method number 7, PM7, is the first semiempirical method to be successfully tested by modeling crystal structures and heats of formation of solids. PM7 is thus also capable of producing results of useful accuracy for materials science, and constitutes a great improvement over its predecessor, PM6. In this article, we present Sparkle Model parameters to be used with PM7 that allow the prediction of geometries of metal complexes and materials which contain lanth...

Hydrogenated amorphous silicon radiation detectors: Material parameters; radiation hardness; charge collection

International Nuclear Information System (INIS)

Qureshi, S.

1991-01-01

Properties of hydrogenated amorphous silicon p-i-n diodes relevant to radiation detection applications were studied. The interest in using this material for radiation detection applications in physics and medicine was motivated by its high radiation hardness and the fact that it can be deposited over large area at relatively low cost. Thick, fully depleted a-Si:H diodes are required for sufficient energy deposition by a charged particle and better signal to noise ratio. A sizeable electric field is essential for charge collection in a -Si:H diodes. The large density of ionized defects that exist in the i layer when the diode is under DC bias causes the electric field to be uniform. Material parameters, namely carrier mobility and lifetime and the ionized defect density in thick a-Si:H p-i-n diodes were studied by the transient photoconductivity method. The increase in diode leakage current with reverse bias over the operating bias was consistent with the Poole-Frenkel effect, involving excitation of carriers from neutral defects. The diode noise over the operating voltage range was completely explained in terms of the shot noise component for CR-(RC) 4 (pseudo-Gaussian) shaping at 3 μs shaping time and the noise component at 0 V bias (delta and thermal noise) added in quadrature. Irradiation with 1 Mev neutrons produced no significant degradation in leakage current and noise at fluences exceeding 4 x 10 14 cm -2 . Irradiation with 1.4 Mev proton fluence of 1 x 10 14 cm -2 decreased carrier lifetime by a factor of ∼4. Degradation in leakage current and noise became significant at proton fluence of ∼10 13 cm -2

Material parameters and vector scaling in transformation acoustics

International Nuclear Information System (INIS)

Cummer, Steven A; Rahm, Marco; Schurig, David

2008-01-01

The degree to which the coordinate transformation concept first demonstrated for electromagnetic waves can be applied to other classes of waves remains an open question. In this work, we thoroughly examine the coordinate transformation invariance of acoustic waves. We employ a purely physical argument to show how the acoustic velocity vector must transform differently than the E and H fields in Maxwell's equations, which explains why acoustic coordinate transformation invariance was not found in some previous analyses. A first principles analysis of the acoustic equations under arbitrary coordinate transformations confirms that the divergence operator is preserved only if velocity transforms in this physically correct way. This analysis also yields closed-form expressions for the bulk modulus and mass density tensor of the material required to realize an arbitrary coordinate transformation on the acoustic fields, which we show are equivalent to forms presented elsewhere. We demonstrate the computation of these material parameters in two specific cases and show that the change in velocity and pressure gradient vectors under a nonorthogonal coordinate transformation is precisely how these vectors must change from purely physical arguments. This analysis confirms that all of the electromagnetic devices and materials that have been conceived using the coordinate transformation approach are also in principle realizable for acoustic waves. Together with previous work, this analysis also shows how the curl, divergence and gradient operators maintain form under arbitrary coordinate transformations, opening the door to analyzing other wave systems built on these three vector operators.

Guided ultrasonic waves for determining effective orthotropic material parameters of continuous-fiber reinforced thermoplastic plates.

Science.gov (United States)

Webersen, Manuel; Johannesmann, Sarah; Düchting, Julia; Claes, Leander; Henning, Bernd

2018-03-01

Ultrasonic methods are widely established in the NDE/NDT community, where they are mostly used for the detection of flaws and structural damage in various components. A different goal, despite the similar technological approach, is non-destructive material characterization, i.e. the determination of parameters like Young's modulus. Only few works on this topic have considered materials with high damping and strong anisotropy, such as continuous-fiber reinforced plastics, but due to the increasing demand in the industry, appropriate methods are needed. In this contribution, we demonstrate the application of laser-induced ultrasonic Lamb waves for the characterization of fiber-reinforced plastic plates, providing effective parameters for a homogeneous, orthotropic material model. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of reference ranges for full blood count parameters in neonatal cord plasma in Hilla, Babil, Iraq

Directory of Open Access Journals (Sweden)

Al-Marzoki JM

2012-10-01

Full Text Available Jasim M Al-Marzoki1, Zainab W Al-Maaroof2, Ali H Kadhum31Department of Pediatrics, 2Department of Pathology, Babylon Medical College, 3Babylon Gynecology and Pediatric Teaching Hospital, Hilla, IraqBackground: The health of an individual is known to vary in different countries, in the same country at different times, and in the same individuals at different ages. This means that the condition of individuals must be related to or compared with reference data. Determination of a reference range for the healthy term newborn is clinically important in terms of various complete blood count parameters. The purpose of this study was to establish a local reference range for full blood count parameters in neonatal cord plasma in Hilla, Babil, Iraq.Methods: A total of 220 mothers and their neonates were enrolled in this cross-sectional study from February 2011 to January 2012. Maternal inclusion criteria were age 15–45 years, an uneventful pregnancy, and hemoglobin ≥ 10 g. Neonatal inclusion criteria were full term (37–42 weeks and normal birth weight. The umbilical cord was immediately clamped after delivery of the baby; 3 mL of cord blood was then taken from the umbilical vein and collected in a tube containing ethylenediamine tetra-acetic acid, its plasma was analyzed for full blood count parameters by standard Coulter gram, and the differential leukocyte count was done manually.Results: Mean neonatal hemoglobin was 13.88 ± 1.34 (range 11–17.3 g/dL and mean white cell count was 10.12 ± 2.8 (range 3.1–21.6 × 109/L. Mean platelet count was 267.63 ± 60.62 (range 152–472 × 109/L. No significant differences in red cell, white cell, or platelet counts were found between males and females, except for neutrophil count. The current study shows lower levels of hemoglobin, white cells, and red cells compared with other studies, and there is agreement with some studies and disagreement with others concerning platelet count.Conclusion: Most results

Raw material changes and their processing parameters in an extrusion cooking process

DEFF Research Database (Denmark)

Cheng, Hongyuan; Friis, Alan

In this work, the effects of raw material and process parameters on product expansion in a fish feed extrusion process were investigated. Four different recipes were studied with a pilot-scale twin-screw co-rotating extruder according to a set of pre-defined processing conditions. In the four rec...

Effective conductivity and permittivity of unsaturated porous materials in the frequency range 1 mHz–1GHz

Science.gov (United States)

Revil, A

2013-01-01

A model combining low-frequency complex conductivity and high-frequency permittivity is developed in the frequency range from 1 mHz to 1 GHz. The low-frequency conductivity depends on pore water and surface conductivities. Surface conductivity is controlled by the electrical diffuse layer, the outer component of the electrical double layer coating the surface of the minerals. The frequency dependence of the effective quadrature conductivity shows three domains. Below a critical frequency fp, which depends on the dynamic pore throat size Λ, the quadrature conductivity is frequency dependent. Between fp and a second critical frequency fd, the quadrature conductivity is generally well described by a plateau when clay minerals are present in the material. Clay-free porous materials with a narrow grain size distribution are described by a Cole-Cole model. The characteristic frequency fd controls the transition between double layer polarization and the effect of the high-frequency permittivity of the material. The Maxwell-Wagner polarization is found to be relatively negligible. For a broad range of frequencies below 1 MHz, the effective permittivity exhibits a strong dependence with the cation exchange capacity and the specific surface area. At high frequency, above the critical frequency fd, the effective permittivity reaches a high-frequency asymptotic limit that is controlled by the two Archie's exponents m and n like the low-frequency electrical conductivity. The unified model is compared with various data sets from the literature and is able to explain fairly well a broad number of observations with a very small number of textural and electrochemical parameters. It could be therefore used to interpret induced polarization, induction-based electromagnetic methods, and ground penetrating radar data to characterize the vadose zone. PMID:23576823

The constitutive compatibility method for identification of material parameters based on full-field measurements

KAUST Repository

Moussawi, Ali

2013-10-01

We revisit here the concept of the constitutive relation error for the identification of elastic material parameters based on image correlation. An additional concept, so called constitutive compatibility of stress, is introduced defining a subspace of the classical space of statically admissible stresses. The key idea is to define stresses as compatible with the observed deformation field through the chosen class of constitutive equation. This makes possible the uncoupling of the identification of stress from the identification of the material parameters. As a result, the global cost of the identification is strongly reduced. This uncoupling also leads to parametrized solutions in cases where the solution is non-unique as demonstrated on 2D numerical examples. © 2013 Elsevier B.V.

Reference Physiological Ranges for Serum Biochemical Parameters ...

African Journals Online (AJOL)

drugs includes measurement of changes in physiological parameters of subjects from known established baseline ... Methods: After informed consent, blood and urine samples were collected from a total of 576 ... a major public health problem in Cameroon with a .... sample collection, processing, storage and handling.

Short-range order in the quantum XXZ honeycomb lattice material BaCo2(PO4)2

Science.gov (United States)

Nair, Harikrishnan S.; Brown, J. M.; Coldren, E.; Hester, G.; Gelfand, M. P.; Podlesnyak, A.; Huang, Q.; Ross, K. A.

2018-04-01

We present observations of highly frustrated quasi-two-dimensional (2D) magnetic correlations in the honeycomb lattice layers of the Seff =1 /2 compound γ -BaCo2(PO4)2 (γ -BCPO). Specific heat shows a broad peak comprised of two weak kink features at TN 1˜6 K and TN 2˜3.5 K, the relative weights of which can be modified by sample annealing. Neutron powder diffraction measurements reveal short range quasi-2D order that is established below TN 1 and TN 2, at which two separate, incompatible, short range magnetic orders onset: commensurate antiferromagnetic correlations with correlation length ξc=60 ±2 Å (TN 1) and in quasi-2D helical domains with ξh=350 ±11 Å (TN 2). The ac magnetic susceptibility response lacks frequency dependence, ruling out spin freezing. Inelastic neutron scattering data on γ -BCPO is compared with linear spin wave theory, and two separate parameter regions of the XXZ J1-J2-J3 model with ferromagnetic nearest-neighbor exchange J1 are favored, both near regions of high classical degeneracy. High energy coherent excitations (˜10 meV) persist up to at least 40 K, suggesting strong in-plane correlations persist above TN. These data show that γ -BCPO is a rare highly frustrated, quasi-2D Seff =1 /2 honeycomb lattice material which resists long range magnetic order and spin freezing.

Electron transport system activity of microfouling material: Relationships with biomass parameters

Digital Repository Service at National Institute of Oceanography (India)

Bhosle, N.B.; Tulaskar, A.; Wagh, A.B.

(ETS). The ETS activity ranged from 720 to 1374 ~kg 0@d2@@ dm@u2@@ d@u-1@@. Microfouling biomass and ETS activity of microfouling material increased with the immersion period. ETS activity was significantly correlated with dry weight, organic carbon...

Landau-Devonshire Parameters for the Tunable Paraelectric Material BaTi.9(Sc,Ta).05O3

National Research Council Canada - National Science Library

Miller, Virginia; Crowne, Frank

2008-01-01

...).05O3 are used to deduce the thermodynamic Landau-Devonshire parameters of the material, which are found to differ strongly from those of the parent material BaTiO3, despite the small amount of added Sc and Ta...

Material parameter identification and inverse problems in soft tissue biomechanics

CERN Document Server

Evans, Sam

2017-01-01

The articles in this book review hybrid experimental-computational methods applied to soft tissues which have been developed by worldwide specialists in the field. People developing computational models of soft tissues and organs will find solutions for calibrating the material parameters of their models; people performing tests on soft tissues will learn what to extract from the data and how to use these data for their models and people worried about the complexity of the biomechanical behavior of soft tissues will find relevant approaches to address this complexity.

A goal-oriented field measurement filtering technique for the identification of material model parameters

KAUST Repository

Lubineau, Gilles

2009-05-16

The post-processing of experiments with nonuniform fields is still a challenge: the information is often much richer, but its interpretation for identification purposes is not straightforward. However, this is a very promising field of development because it would pave the way for the robust identification of multiple material parameters using only a small number of experiments. This paper presents a goal-oriented filtering technique in which data are combined into new output fields which are strongly correlated with specific quantities of interest (the material parameters to be identified). Thus, this combination, which is nonuniform in space, constitutes a filter of the experimental outputs, whose relevance is quantified by a quality function based on global variance analysis. Then, this filter is optimized using genetic algorithms. © 2009 Springer-Verlag.

Process Parameter Evaluation and Optimization for Advanced Material Development Final Report CRADA No. TC-1234-96

Energy Technology Data Exchange (ETDEWEB)

Hrubesh, L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); McGann, T. W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2017-10-19

This project was established as a three-year collaboration to produce and characterize · silica aerogels prepared by a Rapid Supercritical Extraction (RSCE) process to meet . BNA, Inc. application requirements. The objectives of this project were to study the parameters necessary to produce optimized aerogel parts with narrowly specified properties and establish the range and limits of the process for producing such aerogels. The project also included development of new aerogel materials useful for high temperature applications. The results of the project were expected to set the conditions necessary to produce quantities of aerogels having particular specifications such as size, shape, density, and mechanical strength. BNA, Inc. terminated the project on April 7, 1999, 10-months prior to the anticipated completion date, due to termination of corporate funding for the project. The technical accomplishments achieved are outlined in Paragraph C below.

Sparkle/PM7 Lanthanide Parameters for the Modeling of Complexes and Materials.

Science.gov (United States)

Dutra, José Diogo L; Filho, Manoel A M; Rocha, Gerd B; Freire, Ricardo O; Simas, Alfredo M; Stewart, James J P

2013-08-13

The recently published Parametric Method number 7, PM7, is the first semiempirical method to be successfully tested by modeling crystal structures and heats of formation of solids. PM7 is thus also capable of producing results of useful accuracy for materials science, and constitutes a great improvement over its predecessor, PM6. In this article, we present Sparkle Model parameters to be used with PM7 that allow the prediction of geometries of metal complexes and materials which contain lanthanide trications. Accordingly, we considered the geometries of 224 high-quality crystallographic structures of complexes for the parameterization set and 395 more for the validation of the parameterization for the whole lanthanide series, from La(III) to Lu(III). The average unsigned error for Sparkle/PM7 for the distances between the metal ion and its coordinating atoms is 0.063Å for all lanthanides, ranging from a minimum of 0.052Å for Tb(III) to 0.088Å for Ce(III), comparable to the equivalent errors in the distances predicted by PM7 for other metals. These distance deviations follow a gamma distribution within a 95% level of confidence, signifying that they appear to be random around a mean, confirming that Sparkle/PM7 is a well-tempered method. We conclude by carrying out a Sparkle/PM7 full geometry optimization of two spatial groups of the same thulium-containing metal organic framework, with unit cells accommodating 376 atoms, of which 16 are Tm(III) cations; the optimized geometries were in good agreement with the crystallographic ones. These results emphasize the capability of the use of the Sparkle Model for the prediction of geometries of compounds containing lanthanide trications within the PM7 semiempirical model, as well as the usefulness of such semiempirical calculations for materials modeling. Sparkle/PM7 is available in the software package MOPAC2012, at no cost for academics and can be obtained from http://openmopac.net.

The constitutive compatibility method for identification of material parameters based on full-field measurements

KAUST Repository

Moussawi, Ali; Lubineau, Gilles; Florentin, É ric; Blaysat, Benoî t

2013-01-01

We revisit here the concept of the constitutive relation error for the identification of elastic material parameters based on image correlation. An additional concept, so called constitutive compatibility of stress, is introduced defining a subspace

A comparison between two powder compaction parameters of plasticity: the effective medium A parameter and the Heckel 1/K parameter.

Science.gov (United States)

Mahmoodi, Foad; Klevan, Ingvild; Nordström, Josefina; Alderborn, Göran; Frenning, Göran

2013-09-10

The purpose of the research was to introduce a procedure to derive a powder compression parameter (EM A) representing particle yield stress using an effective medium equation and to compare the EM A parameter with the Heckel compression parameter (1/K). 16 pharmaceutical powders, including drugs and excipients, were compressed in a materials testing instrument and powder compression profiles were derived using the EM and Heckel equations. The compression profiles thus obtained could be sub-divided into regions among which one region was approximately linear and from this region, the compression parameters EM A and 1/K were calculated. A linear relationship between the EM A parameter and the 1/K parameter was obtained with a strong correlation. The slope of the plot was close to 1 (0.84) and the intercept of the plot was small in comparison to the range of parameter values obtained. The relationship between the theoretical EM A parameter and the 1/K parameter supports the interpretation of the empirical Heckel parameter as being a measure of yield stress. It is concluded that the combination of Heckel and EM equations represents a suitable procedure to derive a value of particle plasticity from powder compression data. Copyright © 2013 Elsevier B.V. All rights reserved.

New parameters in adaptive testing of ferromagnetic materials utilizing magnetic Barkhausen noise

International Nuclear Information System (INIS)

Pal’a, Jozef; Ušák, Elemír

2016-01-01

A new method of magnetic Barkhausen noise (MBN) measurement and optimization of the measured data processing with respect to non-destructive evaluation of ferromagnetic materials was tested. Using this method we tried to found, if it is possible to enhance sensitivity and stability of measurement results by replacing the traditional MBN parameter (root mean square) with some new parameter. In the tested method, a complex set of the MBN from minor hysteresis loops is measured. Afterward, the MBN data are collected into suitably designed matrices and optimal parameters of MBN with respect to maximum sensitivity to the evaluated variable are searched. The method was verified on plastically deformed steel samples. It was shown that the proposed measuring method and measured data processing bring an improvement of the sensitivity to the evaluated variable when comparing with measuring traditional MBN parameter. Moreover, we found a parameter of MBN, which is highly resistant to the changes of applied field amplitude and at the same time it is noticeably more sensitive to the evaluated variable. - Highlights: • We test an adaptive magnetic Barkhausen noise method. • The method utilizes measuring a complex set of Barkhausen noise signals. • We define new matrices of parameters for this method. • The pulse density is highly resistant to changes in applied field amplitude.

Measurement and modeling of hyperfine parameters in ferroic materials

CERN Document Server

Gonçalves, João Nuno; Correia, J G

This thesis presents the results of perturbed angular correlation (PAC) experiments , an experimental technique which measures the hyperfine interaction at probes (radioactive ions implanted in the materials to study), from which one infers local information on an atomic scale. Furthermore, abinitio calculations using density functional theory electronic obtain results that directly complement the experiments, and are also used for theoretical research. These methods were applied in two families of materials. The manganites, with the possible existence of magnetic, charge, orbital and ferroelectric orders, are of fundamental and technological interest. The experimental results are obtained in the alkaline-earth manganites (Ca, Ba, Sr), with special interest due to the structural variety of possible polymorphs. With probes of Cd and In the stability of the probe and its location in a wide temperature range is established and a comparison with calculations allows the physical interpretation of the results. Cal...

Determination of electromagnetic absorption parameters by reflection measurements

International Nuclear Information System (INIS)

Vittitoe, C.N.

1975-09-01

The method described is for determining the electromagnetic absorption parameters of a material by measuring the optical reflection from a thick sample. With linearly polarized incident light (both perpendicular to and parallel to the plane of incidence), the ratio of the reflected intensities at three or more angles of incidence offers promise for determining the complex index of refraction of a material for a broad range of parameter values. The method may be applicable to molten materials, such as UO 2 , where high temperatures cause corrosion and containment difficulties. A method is given for extending the data to neighboring frequencies. Use of the method was successful for all portions of the complex index of refraction plane except for small values of the extinction coefficient

NATO Advanced Research Workshop on Smart Materials for Ranging Systems

CERN Document Server

Franse, Jaap; Sirenko, Valentyna

2006-01-01

The problem of determining the location of an object (usually called ranging) attracts at present much attention in different areas of applications, among them in ecological and safety devices. Electromagnetic waves along with sound waves are widely used for these purposes. Different aspects of materials with specific magnetic, electric and elastic properties are considered in view of potential application in the design and manufacturing of smart materials. Progress is reported in the fabrication and understanding of in-situ formation and characterization of solid state structures with specified properties. Attention is paid to the observation and study of the mobility of magnetic structures and of the kinetics of magnetic ordering transitions. Looking from a different perspective, one of the outcomes of the ARW is the emphasis on the important role that collective phenomena (like spin waves in systems with a magnetically ordered ground state, or critical currents in superconductors) could play at the design ...

Determination of reference ranges for full blood count parameters in neonatal cord plasma in Hilla, Babil, Iraq

Science.gov (United States)

Al-Marzoki, Jasim M; Al-Maaroof, Zainab W; Kadhum, Ali H

2012-01-01

Background The health of an individual is known to vary in different countries, in the same country at different times, and in the same individuals at different ages. This means that the condition of individuals must be related to or compared with reference data. Determination of a reference range for the healthy term newborn is clinically important in terms of various complete blood count parameters. The purpose of this study was to establish a local reference range for full blood count parameters in neonatal cord plasma in Hilla, Babil, Iraq. Methods A total of 220 mothers and their neonates were enrolled in this cross-sectional study from February 2011 to January 2012. Maternal inclusion criteria were age 15–45 years, an uneventful pregnancy, and hemoglobin ≥ 10 g. Neonatal inclusion criteria were full term (37–42 weeks) and normal birth weight. The umbilical cord was immediately clamped after delivery of the baby; 3 mL of cord blood was then taken from the umbilical vein and collected in a tube containing ethylenediamine tetra-acetic acid, its plasma was analyzed for full blood count parameters by standard Coulter gram, and the differential leukocyte count was done manually. Results Mean neonatal hemoglobin was 13.88 ± 1.34 (range 11–17.3) g/dL and mean white cell count was 10.12 ± 2.8 (range 3.1–21.6) × 109/L. Mean platelet count was 267.63 ± 60.62 (range 152–472) × 109/L. No significant differences in red cell, white cell, or platelet counts were found between males and females, except for neutrophil count. The current study shows lower levels of hemoglobin, white cells, and red cells compared with other studies, and there is agreement with some studies and disagreement with others concerning platelet count. Conclusion Most results in the current study were within the reference range. The hematological reference values for Iraqi neonatal cord plasma need to be confirmed by larger numbers of blood samples and by collecting samples from

Organic electronic materials: Recent advances in the dft description of the ground and excited states using tuned range-separated hybrid functionals

KAUST Repository

Körzdörfer, Thomas

2014-11-18

Density functional theory (DFT) and its time-dependent extension (TD-DFT) are powerful tools enabling the theoretical prediction of the ground- and excited-state properties of organic electronic materials with reasonable accuracy at affordable computational costs. Due to their excellent accuracy-to-numerical-costs ratio, semilocal and global hybrid functionals such as B3LYP have become the workhorse for geometry optimizations and the prediction of vibrational spectra in modern theoretical organic chemistry. Despite the overwhelming success of these out-of-the-box functionals for such applications, the computational treatment of electronic and structural properties that are of particular interest in organic electronic materials sometimes reveals severe and qualitative failures of such functionals. Important examples include the overestimation of conjugation, torsional barriers, and electronic coupling as well as the underestimation of bond-length alternations or excited-state energies in low-band-gap polymers.In this Account, we highlight how these failures can be traced back to the delocalization error inherent to semilocal and global hybrid functionals, which leads to the spurious delocalization of electron densities and an overestimation of conjugation. The delocalization error for systems and functionals of interest can be quantified by allowing for fractional occupation of the highest occupied molecular orbital. It can be minimized by using long-range corrected hybrid functionals and a nonempirical tuning procedure for the range-separation parameter.We then review the benefits and drawbacks of using tuned long-range corrected hybrid functionals for the description of the ground and excited states of π-conjugated systems. In particular, we show that this approach provides for robust and efficient means of characterizing the electronic couplings in organic mixed-valence systems, for the calculation of accurate torsional barriers at the polymer limit, and for the

Efficient Parameter Searches for Colloidal Materials Design with Digital Alchemy

Science.gov (United States)

Dodd, Paul, M.; Geng, Yina; van Anders, Greg; Glotzer, Sharon C.

Optimal colloidal materials design is challenging, even for high-throughput or genomic approaches, because the design space provided by modern colloid synthesis techniques can easily have dozens of dimensions. In this talk we present the methodology of an inverse approach we term ''digital alchemy'' to perform rapid searches of design-paramenter spaces with up to 188 dimensions that yield thermodynamically optimal colloid parameters for target crystal structures with up to 20 particles in a unit cell. The method relies only on fundamental principles of statistical mechanics and Metropolis Monte Carlo techniques, and yields particle attribute tolerances via analogues of familiar stress-strain relationships.

[Influence of reverse osmosis concentrate on physicochemical parameters of Sini decoction material system and their relevance].

Science.gov (United States)

Jin, Tang-Hui; Zhang, Liu-Hong; Zhu, Hua-Xu; Guo, Li-Wei; Li, Bo; Lu, Ming-Ming

2014-04-01

By studying the process of reverse osmosis system for traditional Chinese medicine materials physicochemical parameters affecting the osmotic pressure of its relevance, new compound system reverse osmosis process design methods were explored. Three concentrations materials for high, middle and low were dubbed with Sini decoction as a model drug, and pretreated by 50 thousand relative molecular weight cut-off ultrafiltration membrane. The viscosity, turbidity, conductivity, salinity, TDS, pH value and osmotic pressure of each sample were determined after the reverse osmosis to study the physical and chemical parameters between their respective correlations with the osmotic pressure, and characterized by HPLC chromatograms showing changes before and after the main chemical composition of samples of reverse osmosis. Conductivity-osmotic pressure, salinity-osmotic pressure of the linear correlation coefficient, TDS-osmotic pressure between the three sets of parameters were 0.963 8, 0.932 7, 0.973 7, respectively. Reverse osmosis concentrate and its characteristic spectrum ultrafiltrate HPLC similarity were up to 0. 968 or more, except the low concentrations. There is a significant correlation between the three physicochemical parameters (conductivity, salinity, TDS) and osmotic pressure of each sample system, and there is also significant linear correlation between salinity, conductivity, TDS. The original chemical composition of Sini decoction material concentrate was completely remained after the process of reverse osmosis.

Absorbent material for type a radioactive materials packaging containing liquids

International Nuclear Information System (INIS)

Saunders, G.A.

1989-11-01

The application of absorbent materials to the packaging and transport of liquid radioactive materials in Type A packages has not been reported in the literature. However, a significant body of research exists on absorbent materials for personal hygiene products such as diapers. Absorption capacity is dependent on both the absorbent material and the liquid being absorbed. Theoretical principles for capillary absorption in both the horizontal and the vertical plane indicate that small contact angle between the absorbent fibre and the liquid, and a small inter-fibre pore size are important. Some fluid parameters such as viscosity affect the rate of absorption but not the final absorption capacity. There appears to be little comparability between results obtained for the same absorbent and fluid using different test procedures. Test samples of materials from several classes of potential absorbents have been evaluated in this study, and shown to have a wide range of absorbent capacities. Foams, natural fibres, artificial fibres and granular materials are all potentially useful absorbents, with capacities ranging from as little as 0.86 to as much as 40.6 grams of distilled water per gram of absorbent. Two experimental procedures for evaluating the absorbent capacity of these materials have been detailed in this report, and found suitable for evaluating granular, fibrous or foam materials. Compression of the absorbent material reduces its capacity, but parameters such as relative humidity, pH, temperature, and viscosity appear to have little significant influence on capacity. When the materials were loaded to 50% of their one-minute absorbency, subsequent loss of the absorbed liquid was generally minimal. All of the absorbent materials rapidly lost their absorbed water through evaporation within twenty-four hours in still air at 21 degrees C and 50% relative humidity

An accurate energy-range relationship for high-energy electron beams in arbitrary materials

International Nuclear Information System (INIS)

Sorcini, B.B.; Brahme, A.

1994-01-01

A general analytical energy-range relationship has been derived to relate the practical range, R p to the most probable energy, E p , of incident electron beams in the range 1 to 50 MeV and above, for absorbers of any atomic number. In the present study only Monte Carlo data determined with the new ITS.3 code have been employed. The standard deviations of the mean deviation from the Monte Carlo data at any energy are about 0.10, 0.12, 0.04, 0.11, 0.04, 0.03, 0.02 mm for Be, C, H 2 O, Al, Cu, Ag and U, respectively, and the relative standard deviation of the mean is about 0.5% for all materials. The fitting program gives some priority to water-equivalent materials, which explains the low standard deviation for water. A small error in the fall-off slope can give a different value for R p . We describe a new method which reduces the uncertainty in the R p determination, by fitting an odd function to the descending portion of the depth-dose curve in order to accurately determine the tangent at the inflection point, and thereby the practical range. An approximate inverse relation is given expressing the most probable energy of an electron beam as a function of the practical range. The resultant relative standard error of the energy is less than 0.7%, and the maximum energy error ΔE p is less than 0.3 MeV. (author)

Determination of kinetic parameters during the thermal decomposition of epoxy/carbon fiber composite material

International Nuclear Information System (INIS)

Lee, Jae Hun; Kim, Kwang Seok; Kim, Hyo

2013-01-01

An in-depth study to determine the thermal decomposition kinetics parameters such as the activation energy E_a, the reaction order n, and the pre-exponential factor A of epoxy/carbon fiber composite material has been conducted. We employ not only the modified peak property method that is proposed here, but also the conventional method in analyzing the experimental data, and compare the results to show the performance of the proposed model. The pyrolysis tests for the epoxy/carbon fiber composite materials are conducted by using thermogravimetric analyser at various heating rates. As a result, the best prediction to the experimental data can be obtained by the modified peak property method. Besides, among the methods applied here, the modified peak property method provides most convenient way to recover the parameters: it does not require a curve fitting of the data nor a long iterative computation

Quantitative assessment of image artifacts from root filling materials on CBCT scans made using several exposure parameters

Energy Technology Data Exchange (ETDEWEB)

Rabelo, Katharina Alves; Cavalcanti, Yuri Wanderley; De Oliveira Pinto, Martina Gerlane; De Melo, Daniela Pita [Dept. of Oral Diagnosis, State University of Paraiba, Campina Grande (Brazil); Melo, Saulo Leonardo Sousa [Dept. of Oral Pathology, Radiology and Medicine, University of Iowa, Iowa City (United States); Campos, Paulo Sergio Flores; De Andrade Freitas Oliveira, Luciana Soares [Federal University of Bahia, Salvador (Brazil)

2017-09-15

To quantify artifacts from different root filling materials in cone-beam computed tomography (CBCT) images acquired using different exposure parameters. Fifteen single-rooted teeth were scanned using 8 different exposure protocols with 3 different filling materials and once without filling material as a control group. Artifact quantification was performed by a trained observer who made measurements in the central axial slice of all acquired images in a fixed region of interest using ImageJ. Hyperdense artifacts, hypodense artifacts, and the remaining tooth area were identified, and the percentages of hyperdense and hypodense artifacts, remaining tooth area, and tooth area affected by the artifacts were calculated. Artifacts were analyzed qualitatively by 2 observers using the following scores: absence (0), moderate presence (1), and high presence (2) for hypodense halos, hypodense lines, and hyperdense lines. Two-way ANOVA and the post-hoc Tukey test were used for quantitative and qualitative artifact analysis. The Dunnet test was also used for qualitative analysis. The significance level was set at P<.05. There were no significant interactions among the exposure parameters in the quantitative or qualitative analysis. Significant differences were observed among the studied filling materials in all quantitative analyses. In the qualitative analyses, all materials differed from the control group in terms of hypodense and hyperdense lines (P<.05). Fiberglass posts did not differ statistically from the control group in terms of hypodense halos (P>.05). Different exposure parameters did not affect the objective or subjective observations of artifacts in CBCT images; however, the filling materials used in endodontic restorations did affect both types of assessments.

Using constitutive equation gap method for identification of elastic material parameters: Technical insights and illustrations

KAUST Repository

Florentin, Éric

2011-08-09

The constitutive equation gap method (CEGM) is a well-known concept which, until now, has been used mainly for the verification of finite element simulations. Recently, CEGM-based functional has been proposed to identify local elastic parameters based on experimental full-field measurement. From a technical point of view, this approach requires to quickly describe a space of statically admissible stress fields. We present here the technical insights, inspired from previous works in verification, that leads to the construction of such a space. Then, the identification strategy is implemented and the obtained results are compared with the actual material parameters for numerically generated benchmarks. The quality of the identification technique is demonstrated that makes it a valuable tool for interactive design as a way to validate local material properties. © 2011 Springer-Verlag.

Evaluation of a point-of-care blood analyzer and determination of reference ranges for blood parameters in rockfish.

Science.gov (United States)

Harrenstien, Lisa A; Tornquist, Susan J; Miller-Morgan, Timothy J; Fodness, Brian G; Clifford, Kevin E

2005-01-15

To compare values of blood parameters in rockfish obtained by use of a point-of-care portable blood analyzer with values determined by a veterinary diagnostic laboratory, calculate reference ranges for various blood parameters in black rockfish, and compare values of blood parameters in clinically normal fish with those of fish with clinical abnormalities. Prospective study. 41 captive adult black rockfish (Sebastes melanops) and 4 captive adult blue rockfish (Sebastes mystinus). Rockfish were anesthetized with tricaine methanesulfonate for collection of blood samples. Heparinized blood samples were immediately analyzed with a point-of-care analyzer. Blood sodium, potassium, chloride, urea nitrogen, and glucose concentrations; Hct; pH; partial pressure of carbon dioxide; total carbon dioxide concentration; bicarbonate concentration; base excess; and hemoglobin concentration were determined. A microhematocrit technique was used to determine PCV, and a refractometer was used to estimate total plasma protein concentration. Paired heparinized blood samples were transported to a veterinary diagnostic laboratory for analyses. Data obtained with the point-of-care analyzer were reproducible; however, values for most blood parameters were significantly different from those obtained by the veterinary diagnostic laboratory. Fish with poor body condition had several blood parameter values that were lower than corresponding values in clinically normal fish. Point-of-care blood analyses may prove useful in rockfish. Point-of-care data for a large number of clinically normal fish must be obtained for reference ranges to be calculated, and further assessments of clinically abnormal fish are necessary to determine the relevance of the data.

Ultra-Weak Fiber Bragg Grating Sensing Network Coated with Sensitive Material for Multi-Parameter Measurements

Directory of Open Access Journals (Sweden)

Wei Bai

2017-06-01

Full Text Available A multi-parameter measurement system based on ultra-weak fiber Bragg grating (UFBG array with sensitive material was proposed and experimentally demonstrated. The UFBG array interrogation principle is time division multiplex technology with two semiconductor optical amplifiers as timing units. Experimental results showed that the performance of the proposed UFBG system is almost equal to that of traditional FBG, while the UFBG array system has obvious superiority with potential multiplexing ability for multi-point and multi-parameter measurement. The system experimented on a 144 UFBG array with the reflectivity of UFBG ~0.04% for the four target parameters: hydrogen, humidity, temperature and salinity. Moreover, a uniform solution was customized to divide the cross-sensitivity between temperature and other target parameters. It is expected that this scheme will be capable of handling thousands of multi-parameter sensors in a single fiber.

Ultra-Weak Fiber Bragg Grating Sensing Network Coated with Sensitive Material for Multi-Parameter Measurements.

Science.gov (United States)

Bai, Wei; Yang, Minghong; Hu, Chenyuan; Dai, Jixiang; Zhong, Xuexiang; Huang, Shuai; Wang, Gaopeng

2017-06-26

A multi-parameter measurement system based on ultra-weak fiber Bragg grating (UFBG) array with sensitive material was proposed and experimentally demonstrated. The UFBG array interrogation principle is time division multiplex technology with two semiconductor optical amplifiers as timing units. Experimental results showed that the performance of the proposed UFBG system is almost equal to that of traditional FBG, while the UFBG array system has obvious superiority with potential multiplexing ability for multi-point and multi-parameter measurement. The system experimented on a 144 UFBG array with the reflectivity of UFBG ~0.04% for the four target parameters: hydrogen, humidity, temperature and salinity. Moreover, a uniform solution was customized to divide the cross-sensitivity between temperature and other target parameters. It is expected that this scheme will be capable of handling thousands of multi-parameter sensors in a single fiber.

Impact reduction of the uncertain geometrical parameters on magnetic material identification of an EI electromagnetic inductor using an adaptive inverse algorithm

International Nuclear Information System (INIS)

Abdallh, A.; Crevecoeur, G.; Dupré, L.

2012-01-01

The magnetic characteristics of the electromagnetic devices' core materials can be recovered by solving an inverse problem, where sets of measurements need to be properly interpreted using a forward numerical model of the device. However, the uncertainties of the geometrical parameter values in the forward model lead to appreciable recovery errors in the recovered values of the material parameters. In this paper, we propose an effective inverse approach technique, in which the influences of the uncertainties in the geometrical model parameters are minimized. In this proposed approach, the cost function that needs to be minimized is adapted with respect to the uncertain geometrical model parameters. The proposed methodology is applied onto the identification of the magnetizing B–H curve of the magnetic material of an EI core inductor. The numerical results show a significant reduction of the recovery errors in the identified magnetic material parameter values. Moreover, the proposed methodology is validated by solving an inverse problem starting from real magnetic measurements. - Highlights: ► A new method to minimize the influence of the uncertain parameters in inverse problems is proposed. ► The technique is based on adapting iteratively the objective function that needs to be minimized. ► The objective function is adapted by the model response sensitivity to the uncertain parameters. ► The proposed technique is applied for recovering the B–H curve of an EI core inductor material. ► The error in the inverse problem solution is dramatically reduced using the proposed methodology.

Prediction of detonation and JWL eos parameters of energetic materials using EXPLO5 computer code

CSIR Research Space (South Africa)

Peter, Xolani

2016-09-01

Full Text Available Ballistic Organization Cape Town, South Africa 27-29 September 2016 1 PREDICTION OF DETONATION AND JWL EOS PARAMETERS OF ENERGETIC MATERIALS USING EXPLO5 COMPUTER CODE X. Peter*, Z. Jiba, M. Olivier, I.M. Snyman, F.J. Mostert and T.J. Sono.... Nowadays many numerical methods and programs are being used for carrying out thermodynamic calculations of the detonation parameters of condensed explosives, for example a BKW Fortran (Mader, 1967), Ruby (Cowperthwaite and Zwisler, 1974) TIGER...

Challenges while Updating Planning Parameters of an ERP System and How a Simulation-Based Support System Can Support Material Planners

Directory of Open Access Journals (Sweden)

Ulrike Stumvoll

2016-01-01

Full Text Available In an Enterprise Resource Planning (ERP system, production planning is influenced by a variety of parameters. Previous investigations show that setting parameter values is highly relevant to a company’s target system. Parameter settings should be checked and adjusted, e.g., after a change in environmental factors, by material planners. In practice, updating the parameters is difficult due to several reasons. This paper presents a simulation-based decision support system, which helps material planners in all stages of decision-making processes. It will present the system prototype’s user interface and the results of applying the system to a case study.

Probabilistic estimation of the constitutive parameters of polymers

Directory of Open Access Journals (Sweden)

Siviour C.R.

2012-08-01

Full Text Available The Mulliken-Boyce constitutive model predicts the dynamic response of crystalline polymers as a function of strain rate and temperature. This paper describes the Mulliken-Boyce model-based estimation of the constitutive parameters in a Bayesian probabilistic framework. Experimental data from dynamic mechanical analysis and dynamic compression of PVC samples over a wide range of strain rates are analyzed. Both experimental uncertainty and natural variations in the material properties are simultaneously considered as independent and joint distributions; the posterior probability distributions are shown and compared with prior estimates of the material constitutive parameters. Additionally, particular statistical distributions are shown to be effective at capturing the rate and temperature dependence of internal phase transitions in DMA data.

Development and Application of a Tool for Optimizing Composite Matrix Viscoplastic Material Parameters

Science.gov (United States)

Murthy, Pappu L. N.; Naghipour Ghezeljeh, Paria; Bednarcyk, Brett A.

2018-01-01

This document describes a recently developed analysis tool that enhances the resident capabilities of the Micromechanics Analysis Code with the Generalized Method of Cells (MAC/GMC) and its application. MAC/GMC is a composite material and laminate analysis software package developed at NASA Glenn Research Center. The primary focus of the current effort is to provide a graphical user interface (GUI) capability that helps users optimize highly nonlinear viscoplastic constitutive law parameters by fitting experimentally observed/measured stress-strain responses under various thermo-mechanical conditions for braided composites. The tool has been developed utilizing the MATrix LABoratory (MATLAB) (The Mathworks, Inc., Natick, MA) programming language. Illustrative examples shown are for a specific braided composite system wherein the matrix viscoplastic behavior is represented by a constitutive law described by seven parameters. The tool is general enough to fit any number of experimentally observed stress-strain responses of the material. The number of parameters to be optimized, as well as the importance given to each stress-strain response, are user choice. Three different optimization algorithms are included: (1) Optimization based on gradient method, (2) Genetic algorithm (GA) based optimization and (3) Particle Swarm Optimization (PSO). The user can mix and match the three algorithms. For example, one can start optimization with either 2 or 3 and then use the optimized solution to further fine tune with approach 1. The secondary focus of this paper is to demonstrate the application of this tool to optimize/calibrate parameters for a nonlinear viscoplastic matrix to predict stress-strain curves (for constituent and composite levels) at different rates, temperatures and/or loading conditions utilizing the Generalized Method of Cells. After preliminary validation of the tool through comparison with experimental results, a detailed virtual parametric study is

ATMOSPHERIC DYNAMICS OF TERRESTRIAL EXOPLANETS OVER A WIDE RANGE OF ORBITAL AND ATMOSPHERIC PARAMETERS

Energy Technology Data Exchange (ETDEWEB)

Kaspi, Yohai [Department of Earth and Planetary Sciences, Weizmann Institute of Science, 234 Herzl st., 76100, Rehovot (Israel); Showman, Adam P., E-mail: yohai.kaspi@weizmann.ac.il [Department of Planetary Sciences and Lunar and Planetary Laboratory, The University of Arizona, 1629 University Blvd., Tucson, AZ 85721 (United States)

2015-05-01

The recent discoveries of terrestrial exoplanets and super-Earths extending over a broad range of orbital and physical parameters suggest that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super-Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone—including transitions to Snowball-like states and runaway-greenhouse feedbacks—depend on the equator-to-pole temperature differences, patterns of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, stellar flux, atmospheric mass, surface gravity, optical thickness, and planetary radius affect the atmospheric circulation and temperature distribution on such planets. Our simulations demonstrate that equator-to-pole temperature differences, meridional heat transport rates, structure and strength of the winds, and the hydrological cycle vary strongly with these parameters, implying that the sensitivity of the planet to global climate feedbacks will depend significantly on the atmospheric circulation. We elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet streams, Hadley and Ferrel cells, and latitudinal temperature differences. Finally, we discuss the implications for understanding how the atmospheric circulation influences the global climate.

ATMOSPHERIC DYNAMICS OF TERRESTRIAL EXOPLANETS OVER A WIDE RANGE OF ORBITAL AND ATMOSPHERIC PARAMETERS

International Nuclear Information System (INIS)

Kaspi, Yohai; Showman, Adam P.

2015-01-01

The recent discoveries of terrestrial exoplanets and super-Earths extending over a broad range of orbital and physical parameters suggest that these planets will span a wide range of climatic regimes. Characterization of the atmospheres of warm super-Earths has already begun and will be extended to smaller and more distant planets over the coming decade. The habitability of these worlds may be strongly affected by their three-dimensional atmospheric circulation regimes, since the global climate feedbacks that control the inner and outer edges of the habitable zone—including transitions to Snowball-like states and runaway-greenhouse feedbacks—depend on the equator-to-pole temperature differences, patterns of relative humidity, and other aspects of the dynamics. Here, using an idealized moist atmospheric general circulation model including a hydrological cycle, we study the dynamical principles governing the atmospheric dynamics on such planets. We show how the planetary rotation rate, stellar flux, atmospheric mass, surface gravity, optical thickness, and planetary radius affect the atmospheric circulation and temperature distribution on such planets. Our simulations demonstrate that equator-to-pole temperature differences, meridional heat transport rates, structure and strength of the winds, and the hydrological cycle vary strongly with these parameters, implying that the sensitivity of the planet to global climate feedbacks will depend significantly on the atmospheric circulation. We elucidate the possible climatic regimes and diagnose the mechanisms controlling the formation of atmospheric jet streams, Hadley and Ferrel cells, and latitudinal temperature differences. Finally, we discuss the implications for understanding how the atmospheric circulation influences the global climate

A 3D domain decomposition approach for the identification of spatially varying elastic material parameters

KAUST Repository

Moussawi, Ali; Lubineau, Gilles; Xu, Jiangping; Pan, Bing

2015-01-01

Summary: The post-treatment of (3D) displacement fields for the identification of spatially varying elastic material parameters is a large inverse problem that remains out of reach for massive 3D structures. We explore here the potential

Microstructural characterization and influence of manufacturing parameters on technological properties of vitreous ceramic materials

Energy Technology Data Exchange (ETDEWEB)

Njoya, D. [Laboratoire de Physico-chimie des Materiaux Mineraux, Departement de Chimie Inorganique, Faculte des Sciences, Universite de Yaounde I, B.P. 812, Yaounde (Cameroon); Laboratoire de Physico-chimie des Materiaux et Environnement, Departement de Chimie, Faculte des Sciences Semlalia, Universite Cadi Ayyad, B.P. 2390, Marrakech (Morocco); Hajjaji, M., E-mail: Hajjaji@ucam.ac.ma [Laboratoire de Physico-chimie des Materiaux et Environnement, Departement de Chimie, Faculte des Sciences Semlalia, Universite Cadi Ayyad, B.P. 2390, Marrakech (Morocco); Bacaoui, A. [Laboratoire de Chimie Organique Appliquee, Departement de Chimie, Faculte des Sciences Semlalia, Universite Cadi Ayyad, B.P. 2390, Marrakech (Morocco); Njopwouo, D. [Laboratoire de Physico-chimie des Materiaux Mineraux, Departement de Chimie Inorganique, Faculte des Sciences, Universite de Yaounde I, B.P. 812, Yaounde (Cameroon)

2010-03-15

Microstructure of vitreous ceramic samples manufactured from kaolinitic-clay and feldspars raw materials from Cameroon was investigated in the range 1150-1250 deg. C by X-ray diffraction and scanning electron microscopy and by measuring some technological properties. Moreover, the simultaneous influence of feldspars content, heating temperature and soaking time on water absorption and firing shrinkage was evaluated by adopting the response surface methodology (Doehlert matrix), using the New Efficient Methodology for Research using Optimal Design (NEMROD) software. The results show that a spinel phase, mullite, glassy phase and some amount of hematite were formed. However, the spinel phase and potassic feldspar, as compared to the sodic one, disappeared at moderate firing temperature and soaking time. Apparently, mullite developed from spinel phase, which is formed from the demixion of metakaolin. On the other hand, it is found that the effects of fluxing content and firing temperature on the measured properties were almost similar and more influent than soaking time. Antagonistic and synergetic interactions existed between the considered parameters, and their importance differed for the considered properties. By using this mathematical tool, suitable operating conditions for manufacturing vitreous bodies were determined.

Microstructural characterization and influence of manufacturing parameters on technological properties of vitreous ceramic materials

International Nuclear Information System (INIS)

Njoya, D.; Hajjaji, M.; Bacaoui, A.; Njopwouo, D.

2010-01-01

Microstructure of vitreous ceramic samples manufactured from kaolinitic-clay and feldspars raw materials from Cameroon was investigated in the range 1150-1250 deg. C by X-ray diffraction and scanning electron microscopy and by measuring some technological properties. Moreover, the simultaneous influence of feldspars content, heating temperature and soaking time on water absorption and firing shrinkage was evaluated by adopting the response surface methodology (Doehlert matrix), using the New Efficient Methodology for Research using Optimal Design (NEMROD) software. The results show that a spinel phase, mullite, glassy phase and some amount of hematite were formed. However, the spinel phase and potassic feldspar, as compared to the sodic one, disappeared at moderate firing temperature and soaking time. Apparently, mullite developed from spinel phase, which is formed from the demixion of metakaolin. On the other hand, it is found that the effects of fluxing content and firing temperature on the measured properties were almost similar and more influent than soaking time. Antagonistic and synergetic interactions existed between the considered parameters, and their importance differed for the considered properties. By using this mathematical tool, suitable operating conditions for manufacturing vitreous bodies were determined.

Long-term effects of water pH changes on hematological parameters ...

African Journals Online (AJOL)

Yomi

2012-02-14

Feb 14, 2012 ... Toxicity of ammonia to fish has been intensively investi- gated in ... MATERIALS AND METHODS. Fish ... to determine the lethal acidic and alkaline ranges. ..... enzymatic parameters of mrigal, Cirrhinus mrigala (Hamilton).

Material parameters for thermoelectric performance

Indian Academy of Sciences (India)

The thermoelectric performance of a thermoelement is ideally defined in terms of the so-called ... However, there are other parameters which are fairly good indicators ... Whereas a final deciding factor reflecting on .... matter of a future work.

Toolpath Strategy and Optimum Combination of Machining Parameter during Pocket Mill Process of Plastic Mold Steels Material

Science.gov (United States)

Wibowo, Y. T.; Baskoro, S. Y.; Manurung, V. A. T.

2018-02-01

Plastic based products spread all over the world in many aspects of life. The ability to substitute other materials is getting stronger and wider. The use of plastic materials increases and become unavoidable. Plastic based mass production requires injection process as well Mold. The milling process of plastic mold steel material was done using HSS End Mill cutting tool that is widely used in a small and medium enterprise for the reason of its ability to be re sharpened and relatively inexpensive. Study on the effect of the geometry tool states that it has an important effect on the quality improvement. Cutting speed, feed rate, depth of cut and radii are input parameters beside to the tool path strategy. This paper aims to investigate input parameter and cutting tools behaviors within some different tool path strategy. For the reason of experiments efficiency Taguchi method and ANOVA were used. Response studied is surface roughness and cutting behaviors. By achieving the expected quality, no more additional process is required. Finally, the optimal combination of machining parameters will deliver the expected roughness and of course totally reduced cutting time. However actually, SMEs do not optimally use this data for cost reduction.

Optimisation of design parameters for modular range enhanced projectile

OpenAIRE

Jelic, Z

2016-01-01

There is an underpinning requirement for artillery systems to achieve longer range, better precision, and an adequate lethal effect. The main objective of this research is to investigate various methods of range increase and propose optimal solution for range extension of existing artillery systems. The proposed solution is novel, modular projectile design. Several methodologies for projectile range increment (such as improved aerodynamics and ballistic profile) were combined to achieve the "...

Compressive Failure Mechanisms in Layered Materials

DEFF Research Database (Denmark)

Sørensen, Kim Dalsten

Two important failure modes in fiber reinforced composite materials in cluding layers and laminates occur under loading conditions dominated by compression in the layer direction. These two distinctly different failure modes are 1. buckling driven delamination 2. failure by strain localization...... or on cylindrical substrates modeling the delamination as an interface fracture mechanical problem. Here attention is directed towards double-curved substrates, which introduces a new non-dimensional combination of geometric parameters. It is shown for a wide range of parameters that by choosing the two....... This has some impact on the convergence rate for decreasing mesh size in the load vs. end shortening response for a rectangular block of material. Especially in the immediate post critical range the convergence rate may be slow. The capabilities of the model to deal with more complicated structural...

Characterizing proton-activated materials to develop PET-mediated proton range verification markers

Science.gov (United States)

Cho, Jongmin; Ibbott, Geoffrey S.; Kerr, Matthew D.; Amos, Richard A.; Stingo, Francesco C.; Marom, Edith M.; Truong, Mylene T.; Palacio, Diana M.; Betancourt, Sonia L.; Erasmus, Jeremy J.; DeGroot, Patricia M.; Carter, Brett W.; Gladish, Gregory W.; Sabloff, Bradley S.; Benveniste, Marcelo F.; Godoy, Myrna C.; Patil, Shekhar; Sorensen, James; Mawlawi, Osama R.

2016-06-01

Conventional proton beam range verification using positron emission tomography (PET) relies on tissue activation alone and therefore requires particle therapy PET whose installation can represent a large financial burden for many centers. Previously, we showed the feasibility of developing patient implantable markers using high proton cross-section materials (18O, Cu, and 68Zn) for in vivo proton range verification using conventional PET scanners. In this technical note, we characterize those materials to test their usability in more clinically relevant conditions. Two phantoms made of low-density balsa wood (~0.1 g cm-3) and beef (~1.0 g cm-3) were embedded with Cu or 68Zn foils of several volumes (10-50 mm3). The metal foils were positioned at several depths in the dose fall-off region, which had been determined from our previous study. The phantoms were then irradiated with different proton doses (1-5 Gy). After irradiation, the phantoms with the embedded foils were moved to a diagnostic PET scanner and imaged. The acquired data were reconstructed with 20-40 min of scan time using various delay times (30-150 min) to determine the maximum contrast-to-noise ratio. The resultant PET/computed tomography (CT) fusion images of the activated foils were then examined and the foils’ PET signal strength/visibility was scored on a 5 point scale by 13 radiologists experienced in nuclear medicine. For both phantoms, the visibility of activated foils increased in proportion to the foil volume, dose, and PET scan time. A linear model was constructed with visibility scores as the response variable and all other factors (marker material, phantom material, dose, and PET scan time) as covariates. Using the linear model, volumes of foils that provided adequate visibility (score 3) were determined for each dose and PET scan time. The foil volumes that were determined will be used as a guideline in developing practical implantable markers.

Electron beam absorption in solid and in water phantoms: depth scaling and energy-range relations

International Nuclear Information System (INIS)

Grosswendt, B.; Roos, M.

1989-01-01

In electron dosimetry energy parameters are used with values evaluated from ranges in water. The electron ranges in water may be deduced from ranges measured in solid phantoms. Several procedures recommended by national and international organisations differ both in the scaling of the ranges and in the energy-range relations for water. Using the Monte Carlo method the application of different procedures for electron energies below 10 MeV is studied for different phantom materials. It is shown that deviations in the range scaling and in the energy-range relations for water may accumulate to give energy errors of several per cent. In consequence energy-range relations are deduced for several solid phantom materials which enable a single-step energy determination. (author)

Research of interaction between technological and material parameters during densification of sunflower hulls

Science.gov (United States)

Križan, Peter; Matúš, Miloš; Beniak, Juraj; Šooš, Ľubomír

2018-01-01

During the biomass densification can be recognized various technological variables and also material parameters which significantly influences the final solid biofuels (pellets) quality. In this paper, we will present the research findings concerning relationships between technological and material variables during densification of sunflower hulls. Sunflower hulls as an unused source is a typical product of agricultural industry in Slovakia and belongs to the group of herbaceous biomass. The main goal of presented experimental research is to determine the impact of compression pressure, compression temperature and material particle size distribution on final biofuels quality. Experimental research described in this paper was realized by single-axis densification, which was represented by experimental pressing stand. The impact of mentioned investigated variables on the final briquettes density and briquettes dilatation was determined. Mutual interactions of these variables on final briquettes quality are showing the importance of mentioned variables during the densification process. Impact of raw material particle size distribution on final biofuels quality was also proven by experimental research on semi-production pelleting plant.

A 3D domain decomposition approach for the identification of spatially varying elastic material parameters

KAUST Repository

Moussawi, Ali

2015-02-24

Summary: The post-treatment of (3D) displacement fields for the identification of spatially varying elastic material parameters is a large inverse problem that remains out of reach for massive 3D structures. We explore here the potential of the constitutive compatibility method for tackling such an inverse problem, provided an appropriate domain decomposition technique is introduced. In the method described here, the statically admissible stress field that can be related through the known constitutive symmetry to the kinematic observations is sought through minimization of an objective function, which measures the violation of constitutive compatibility. After this stress reconstruction, the local material parameters are identified with the given kinematic observations using the constitutive equation. Here, we first adapt this method to solve 3D identification problems and then implement it within a domain decomposition framework which allows for reduced computational load when handling larger problems.

STARCODES, Stopping Power and Ranges for Electrons, Protons, He

International Nuclear Information System (INIS)

2000-01-01

1 - Description of program or function: The 'STAR CODES', ESTAR, PSTAR, and ASTAR, calculate stopping-power and range tables for electrons, protons, and helium ions (alphas), according to methods described in ICRU Reports 37 and 39. 2 - Method of solution: Collision stopping powers are calculated from the theory of Bethe (1930, 1932), with a density-effect correction evaluated according to Sternheimer (1952, 1982). The stopping-power formula contains an important parameter, the mean excitation energy (I-value), which characterizes the stopping properties of a material. The codes provide output for electrons in any stopping material (279 provided) and for protons and helium ions in 74 materials. The calculations include the 1) Collision stopping power, 2) Radiative stopping power (electrons only), 3) Nuclear stopping power (protons and helium ions), 4) Total stopping power, 5) CSDA range, 6) Projected range (protons and helium ions), 7) Density effect parameter (electrons), 8) Radiation yield (electrons), and 9) Detour factor (protons and helium ions). Standard energy grids and files of elements w/ionization-excitation information are included with lookup table capabilities. 3 - Restrictions on the complexity of the problem: The minimum energies used in the calculations are at 1 KeV (protons and helium ions) and 10 KeV (electrons), and the maximum are 1 GeV. The standard energy grids are set at 81 for electrons, equally spaced (logarithmically), 133 for protons, and 122 for helium ions. The lower energy electron calculations (< 10 KeV) have up to 5-10% errors and are considered too fallable

Effect of packaging material on enological parameters and volatile compounds of dry white wine.

Science.gov (United States)

Revi, M; Badeka, A; Kontakos, S; Kontominas, M G

2014-01-01

The enological parameters and volatile compounds of white wine packaged in dark coloured glass and two commercial bag-in-box (BIB) pouches (low density polyethylene - LDPE and ethylene vinyl acetate - EVA lined) were determined for a period of 6 months at 20 °C. Parameters monitored included: titratable acidity, volatile acidity, pH, total SO2, free SO2, colour, volatile compounds and sensory attributes. The BIB packaging materials affected the titratable acidity, total and free SO2 and colour of wine. A substantial portion of the wine aroma compounds was adsorbed by the plastic materials or lost to the environment through leakage of the valve fitment. Between the two plastics, the LDPE lined pouch showed a considerably higher aroma sorption as compared to EVA. Wine packaged in glass retained the largest portion of its aroma compounds. Sensory evaluation showed that white wine packaged in both plastics was of acceptable quality for 3 months vs. at least 6 months for that in glass bottles. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of Pressing Parameters on the Structure of Porous Materials Based on Cobalt and Nickel Powders

Science.gov (United States)

Shustov, V. S.; Rubtsov, N. M.; Alymov, M. I.; Ankudinov, A. B.; Evstratov, E. V.; Zelensky, V. A.

2018-03-01

Porous materials with a bulk porosity of more than 68% were synthesized by powder metallurgy methods from a cobalt-nickel mixture. The effect of the ratio of nickel and cobalt powders used in the synthesis of this porous material (including cases when either nickel or cobalt alone was applied) and the conditions of their compaction on structural parameters, such as open and closed porosities and pose size, was established.

The ETH Zurich AMS facilities: Performance parameters and reference materials

Energy Technology Data Exchange (ETDEWEB)

Christl, M., E-mail: mchristl@phys.ethz.ch [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Vockenhuber, C.; Kubik, P.W.; Wacker, L.; Lachner, J.; Alfimov, V.; Synal, H.-A. [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland)

2013-01-15

The current performance of all three AMS systems in operation at ETH Zurich, the 6 MV HVEC EN-Tandem facility 'TANDEM', the 0.5 MV NEC Pelletron 'TANDY', and the 0.2 MV system 'MICADAS' is summarized. Radionuclides routinely measured with these AMS systems include {sup 10}Be, {sup 14}C, {sup 26}Al, {sup 36}Cl, {sup 41}Ca, {sup 129}I and the actinides. The reference materials used for the normalization of the AMS measurements at the ETH Zurich AMS facilities are presented. This paper therefore is a comprehensive status report of all three AMS systems currently operated by the Laboratory of Ion Beam Physics (LIP) at ETH Zurich and documents their performance and operation parameters.

Prediction of operating parameters range for ammonia removal unit in coke making by-products

Science.gov (United States)

Tiwari, Hari Prakash; Kumar, Rajesh; Bhattacharjee, Arunabh; Lingam, Ravi Kumar; Roy, Abhijit; Tiwary, Shambhu

2018-02-01

Coke oven gas treatment plants are well equipped with distributed control systems (DCS) and therefore recording the vast amount of operational data efficiently. Analyzing the stored information manually from historians is practically impossible. In this study, data mining technique was examined for lowering the ammonia concentration in clean coke oven gas. Results confirm that concentration of ammonia in clean coke oven gas depends on the average PCDC temperature; gas scrubber temperatures stripped liquor flow, stripped liquor concentration and stripped liquor temperature. The optimum operating ranges of the above dependent parameters using data mining technique for lowering the concentration of ammonia is described in this paper.

Structural parameter optimization design for Halbach permanent maglev rail

International Nuclear Information System (INIS)

Guo, F.; Tang, Y.; Ren, L.; Li, J.

2010-01-01

Maglev rail is an important part of the magnetic levitation launch system. Reducing the manufacturing cost of magnetic levitation rail is the key problem for the development of magnetic levitation launch system. The Halbach permanent array has an advantage that the fundamental spatial field is cancelled on one side of the array while the field on the other side is enhanced. So this array used in the design of high temperature superconducting permanent maglev rail could improve the surface magnetic field and the levitation force. In order to make the best use of Nd-Fe-B (NdFeB) material and reduce the cost of maglev rail, the effect of the rail's structural parameters on levitation force and the utilization rate of NdFeB material are analyzed. The optimal ranges of these structural parameters are obtained. The mutual impact of these parameters is also discussed. The optimization method of these structure parameters is proposed at the end of this paper.

Structural parameter optimization design for Halbach permanent maglev rail

Energy Technology Data Exchange (ETDEWEB)

Guo, F., E-mail: guofang19830119@163.co [R and D Center of Applied Superconductivity, Huazhong University of Science and Technology, Wuhan 430074 (China); Tang, Y.; Ren, L.; Li, J. [R and D Center of Applied Superconductivity, Huazhong University of Science and Technology, Wuhan 430074 (China)

2010-11-01

Maglev rail is an important part of the magnetic levitation launch system. Reducing the manufacturing cost of magnetic levitation rail is the key problem for the development of magnetic levitation launch system. The Halbach permanent array has an advantage that the fundamental spatial field is cancelled on one side of the array while the field on the other side is enhanced. So this array used in the design of high temperature superconducting permanent maglev rail could improve the surface magnetic field and the levitation force. In order to make the best use of Nd-Fe-B (NdFeB) material and reduce the cost of maglev rail, the effect of the rail's structural parameters on levitation force and the utilization rate of NdFeB material are analyzed. The optimal ranges of these structural parameters are obtained. The mutual impact of these parameters is also discussed. The optimization method of these structure parameters is proposed at the end of this paper.

Parameters identification in strain-rate and thermal sensitive visco-plastic material model for an alumina dispersion strengthened copper

CERN Document Server

Scapin, M; Peroni, M

2011-01-01

The main objective of this paper is getting strain-hardening, thermal and strain-rate parameters for a material model in order to correctly reproduce the deformation process that occurs in high strain-rate scenario, in which the material reaches also high levels of plastic deformation and temperature. In particular, in this work the numerical inverse method is applied to extract material strength parameters from experimental data obtained via mechanical tests at different strain-rates (from quasi-static loading to high strain-rate) and temperatures (between 20 C and 1000 C) for an alumina dispersion strengthened copper material, which commercial name is GLIDCOP. Thanks to its properties GLIDCOP finds several applications in particle accelerator technologies, where problems of thermal management, combined with structural requirements, play a key role. Currently, it is used for the construction of structural and functional parts of the particle beam collimation system. Since the extreme condition in which the m...

Optimisation of laser welding parameters for welding of P92 material using Taguchi based grey relational analysis

Directory of Open Access Journals (Sweden)

Shanmugarajan B.

2016-08-01

Full Text Available Creep strength enhanced ferritic (CSEF steels are used in advanced power plant systems for high temperature applications. P92 (Cr–W–Mo–V steel, classified under CSEF steels, is a candidate material for piping, tubing, etc., in ultra-super critical and advanced ultra-super critical boiler applications. In the present work, laser welding process has been optimised for P92 material by using Taguchi based grey relational analysis (GRA. Bead on plate (BOP trials were carried out using a 3.5 kW diffusion cooled slab CO2 laser by varying laser power, welding speed and focal position. The optimum parameters have been derived by considering the responses such as depth of penetration, weld width and heat affected zone (HAZ width. Analysis of variance (ANOVA has been used to analyse the effect of different parameters on the responses. Based on ANOVA, laser power of 3 kW, welding speed of 1 m/min and focal plane at −4 mm have evolved as optimised set of parameters. The responses of the optimised parameters obtained using the GRA have been verified experimentally and found to closely correlate with the predicted value.

A Dissipation Gap Method for full-field measurement-based identification of elasto-plastic material parameters

KAUST Repository

Blaysat, Benoît

2012-05-18

Using enriched data such as displacement fields obtained from digital image correlation is a pathway to the local identification of material parameters. Up to now, most of the identification techniques for nonlinear models are based on Finite Element Updating Methods. This article explains how an appropriate use of the Dissipation Gap Method can help in this context and be an interesting alternative to these classical techniques. The Dissipation Gap Methods rely on the concept of error in dissipation that has been used mainly for the verification of finite element simulations. We provide here an original application of these founding developments to the identification of material parameters for nonlinear behaviors. The proposed technique and especially the main technical keypoint of building the admissible fields are described in detail. The approach is then illustrated through the identification of heterogeneous isotropic elasto-plastic properties. The basic numerical features highlighted through these simple examples demonstrate this approach to be a promising tool for nonlinear identification. © 2012 John Wiley & Sons, Ltd.

Determination of material distribution in heading process of small bimetallic bar

Science.gov (United States)

Presz, Wojciech; Cacko, Robert

2018-05-01

The electrical connectors mostly have silver contacts joined by riveting. In order to reduce costs, the core of the contact rivet can be replaced with cheaper material, e.g. copper. There is a wide range of commercially available bimetallic (silver-copper) rivets on the market for the production of contacts. Following that, new conditions in the riveting process are created because the bi-metal object is riveted. In the analyzed example, it is a small size object, which can be placed on the border of microforming. Based on the FEM modeling of the load process of bimetallic rivets with different material distributions, the desired distribution was chosen and the choice was justified. Possible material distributions were parameterized with two parameters referring to desirable distribution characteristics. The parameter: Coefficient of Mutual Interactions of Plastic Deformations and the method of its determination have been proposed. The parameter is determined based of two-parameter stress-strain curves and is a function of these parameters and the range of equivalent strains occurring in the analyzed process. The proposed method was used for the upsetting process of the bimetallic head of the electrical contact. A nomogram was established to predict the distribution of materials in the head of the rivet and the appropriate selection of a pair of materials to achieve the desired distribution.

Modelling flow and work hardening behaviour of cold worked Zr–2.5Nb pressure tube material in the temperature range of 30–600 oC

International Nuclear Information System (INIS)

Dureja, A.K.; Sinha, S.K.; Pawaskar, D.N.; Seshu, P.; Chakravartty, J.K.; Sinha, R.K.

2014-01-01

Under a postulated accident scenario of loss of cooling medium in an Indian Pressurised Heavy Water Reactor (IPHWR), temperature of the pressure tubes can rise and lead to large deformations. In order to investigate the modes of deformation of pressure tube – calandria tube assembly, material property data defining the flow behaviour over a temperature range from room temperature (RT) to 800 o C are needed. It is of practical importance to formulate mathematical equations to describe the stress–strain relationships of a material for a variety of reasons, such as the analysis of forming operations and the assessment of component's performance in service. A number of constitutive relations of empirical nature have been proposed and they have been found very suitable to describe the behaviour of a material. Although these relations are of empirical nature, various metallurgical factors appear to decide applicability of each of these relations. For example, grain size influences mainly the friction stress while the strain hardening is governed by dislocation density. In a recent work, tensile deformation behaviour of pressure tube material of IPHWR has been carried out over a range of temperature and strain rates (Dureja et al., 2011). It has been found that the strength parameters (yield and ultimate tensile strength) vary along the length of the tube with higher strength at the trailing end as compared to the leading end. This stems from cooling of the billet during the extrusion process which results in the variation of microstructure, texture and dislocation density from the leading to the trailing end. In addition, the variation in metallurgical parameters is also expected to influence the work hardening behaviour, which is known to control the plastic instability (related to uniform strain). In the present investigation, the tensile flow and work-hardening behaviour of a cold worked Zr–2.5Nb pressure tube material of IPHWRs has been studied over the

Parameter changes in silicon IMPATT diodes for mm wavelength range exposed to gamma-radiation

International Nuclear Information System (INIS)

Shcherbina, L.V.; Torchinskaya, T.V.; Shcherbina, E.S.; Polupan, G.P.

1999-01-01

We investigated the p + -n-n + -silicon mesa-diodes fabricated using batch technique whose breakdown voltage was 19±1 V. The exposition of IMPATT diodes to 60 Co gamma-radiation was made in the 10 3 to 10 7 Gy dose range. When the gamma-irradiation dose was increased up to (5-8)*10 5 Gy, then the thermal-generation component of the reverse current was monotonously decreasing. The breakdown voltage remained the same during gamma-irradiation. It was shown experimentally that exposition of diodes to (5-8)*10 5 Gy doses of gamma-irradiation led to some drop of both the number of microplasmas in the avalanche breakdown region and the micro plasma noise level. 60 Co gamma-irradiation in the 10 3 -8*10 5 Gy dose range led also to the growth of the microwave output power P out . The decrease of the micro plasma number in the avalanche breakdown region and Pout growth may be explained if one assumes that gamma-irradiation in the 10 3 - 8*10 5 Gy dose range leads to 'healing' of structural defects in the semiconductor due to their interaction with the radiation-induced point defects. The gamma-irradiation dose increase over 8*10 5 Gy results in a storage of some radiation-induced defects in the IMPATT diode base and electrical parameters of diodes are degrading

Connections between borehole geophysical parameters of the quality of cement raw materials

International Nuclear Information System (INIS)

Szabo, L.; Illes, A.

1978-01-01

The raw materials for the cement industry are prospected - according to the recommendations of national authorities - by geophysical methods, too. These include not the determination of the deposit boundary, but also an estimation of the quality of limestone and clay from the point of cement manufacture. No forerunners of such tests exist, so new methods were elaborated. After 12 years of site tests it was found that the correlation between laboratory quality tests and certain geophysical parameters of clay deposits is fair but less close in case of limestone deposits. (author)

Quantitative assessment of image artifacts from root filling materials on CBCT scans made using several exposure parameters

International Nuclear Information System (INIS)

Rabelo, Katharina Alves; Cavalcanti, Yuri Wanderley; De Oliveira Pinto, Martina Gerlane; De Melo, Daniela Pita; Melo, Saulo Leonardo Sousa; Campos, Paulo Sergio Flores; De Andrade Freitas Oliveira, Luciana Soares

2017-01-01

To quantify artifacts from different root filling materials in cone-beam computed tomography (CBCT) images acquired using different exposure parameters. Fifteen single-rooted teeth were scanned using 8 different exposure protocols with 3 different filling materials and once without filling material as a control group. Artifact quantification was performed by a trained observer who made measurements in the central axial slice of all acquired images in a fixed region of interest using ImageJ. Hyperdense artifacts, hypodense artifacts, and the remaining tooth area were identified, and the percentages of hyperdense and hypodense artifacts, remaining tooth area, and tooth area affected by the artifacts were calculated. Artifacts were analyzed qualitatively by 2 observers using the following scores: absence (0), moderate presence (1), and high presence (2) for hypodense halos, hypodense lines, and hyperdense lines. Two-way ANOVA and the post-hoc Tukey test were used for quantitative and qualitative artifact analysis. The Dunnet test was also used for qualitative analysis. The significance level was set at P .05). Different exposure parameters did not affect the objective or subjective observations of artifacts in CBCT images; however, the filling materials used in endodontic restorations did affect both types of assessments

Crack Tip Parameters for Growing Cracks in Linear Viscoelastic Materials

DEFF Research Database (Denmark)

Brincker, Rune

In this paper the problem of describing the asymptotic fields around a slowly growing crack in a linearly viscoelastic material is considered. It is shown that for plane mixed mode problems the asymptotic fields must be described by 6 parameters: 2 stress intensity factors and 4 deformation...... intensity factors. In the special case of a constant Poisson ratio only 2 deformation intensity factors are needed. Closed form solutions are given both for a slowly growing crack and for a crack that is suddenly arrested at a point at the crack extension path. Two examples are studied; a stress boundary...... value problem, and a displacement boundary value problem. The results show that the stress intensity factors and the displacement intensity factors do not depend explicitly upon the velocity of the crack tip....

The impact of material attributes and process parameters on the micronisation of lactose monohydrate.

Science.gov (United States)

Shariare, M H; de Matas, M; York, P; Shao, Q

2011-04-15

Dry powder inhalers (DPIs), which are important medicines for drug delivery to the lungs, require drug particles in the respirable size range of 1-6 μm for optimal lung deposition. Drugs administered by the oral route also derive benefit from particles in this size range owing to their large surface area to volume ratio, which provides potential for rapid dissolution. Micronisation used in the production of particles, however often leads to heterogeneous product containing mechanically activated surfaces with amorphous content. This study was therefore carried out to evaluate the effect of particle properties of three grades of lactose monohydrate, with sizes above and below the brittle-ductile transition (dcrit) and their interaction with process variables on the quality of micronised material. Following an experimental design, the impact of three factors (grinding pressure, injector pressure and feed rate) on the particulate attributes of micronised powders produced from the different size grades was assessed. Processing conditions were shown to be important determinants of powder properties only for the coarsest starting material. Ultrafine material was achieved by processing finer grade feed stock below dcrit. However the resultant product was more crystalline and transformed on heating to the anhydrous state with markedly reduced onset temperature with lower energy surfaces than powders produced from larger sized starting material. Thus the propensity for micronisation of lactose monohydrate can be altered through control of starting materials and optimal settings for process variables. Copyright © 2011 Elsevier B.V. All rights reserved.

Review Paper: Review of Instrumentation for Irradiation Testing of Nuclear Fuels and Materials

International Nuclear Information System (INIS)

Kim, Bong Goo; Rempe, Joy L.; Villard, Jean-Francois; Solstadd, Steinar

2011-01-01

Over 50 years of nuclear fuels and materials irradiation testing has led to many countries developing significant improvements in instrumentation to monitor physical parameters and to control the test conditions in material test reactors (MTRs). Recently, there is increased interest to irradiate new materials and reactor fuels for advanced pressurized water reactors and Gen-IV reactor systems, such as sodium-cooled fast reactors, very high temperature reactors, supercritical water-cooled reactors, and gas-cooled fast reactors. This review paper documents the current state of instrumentation technologies in MTRs in the world and summarizes ongoing research efforts to deploy new sensors. As described in this paper, a wide range of sensors is available to measure key parameters of interest during fuels and materials irradiations in MTRs. Ongoing development efforts focus on providing MTR users a wider range of parameter measurements with smaller, higher accuracy sensors.

Rapid Debris Analysis Project Task 3 Final Report - Sensitivity of Fallout to Source Parameters, Near-Detonation Environment Material Properties, Topography, and Meteorology

Energy Technology Data Exchange (ETDEWEB)

Goldstein, Peter [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2014-01-24

This report describes the sensitivity of predicted nuclear fallout to a variety of model input parameters, including yield, height of burst, particle and activity size distribution parameters, wind speed, wind direction, topography, and precipitation. We investigate sensitivity over a wide but plausible range of model input parameters. In addition, we investigate a specific example with a relatively narrow range to illustrate the potential for evaluating uncertainties in predictions when there are more precise constraints on model parameters.

Model Study of Wave Overtopping of Marine Structure for a Wide Range of Geometric Parameters

DEFF Research Database (Denmark)

Kofoed, Jens Peter

2000-01-01

The objective of the study described in this paper is to enable estimation of wave overtopping rates for slopes/ramps given by a wide range of geometric parameters when subjected to varying wave conditions. To achieve this a great number of model tests are carried out in a wave tank using irregul...... 2-D waves. On the basis of the first part of these tests an exponential overtopping expression for a linear slope, including the effect of limited draught and varying slope angle, is presented. The plans for further tests with other slope geometries are described....

The physical interpretation of the parameters measured during the tensile testing of materials at elevated temperatures

International Nuclear Information System (INIS)

Burton, B.

1984-01-01

Hot tensile (or compression) testing, where the stress developed in a material is measured under an imposed strain rate, is often used as an alternative to conventional creep testing. The advantages of the hot tensile test are that its duration can be more closely controlled by the experimenter and also that the technique is more convenient, since high precision testing machines are available. The main disadvantage is that the interpretation of results is more complex. The present paper relates the parameters which are measured in hot tensile tests, to physical processes which occur in materials deforming by a variety of mechanisms. For cases where no significant structural changes occur, as in viscous or superplastic flow, analytical expressions are derived which relate the stresses measured in these tests to material constants. When deformation is controlled by recovery processes, account has to be taken of the structural changes which occur concurrently. A wide variety of behaviour may then be exhibited which depends on the initial dislocation density, the presence of second-phase particles and the relative values of the recovery rate parameters and the velocity imposed by the testing machine. Numerical examples are provided for simple recovery models. (author)

Simulation of beam-splitter made of metamaterials with angle spatial distribution of constitutive parameters based on transformation optics for THz frequency range

International Nuclear Information System (INIS)

Gurvitz, E A; Vozianova, A V; Khodzitsky, M K

2014-01-01

New approach to design beam splitter on basis of the transformation optics using angle constitutive parameters distribution of medium was proposed. The beam splitter was numerically simulated by COMSOL Multiphysics for terahertz frequency range. The numerical simulations were carried out for ideal and reduced constitutive parameters of medium for the case of TM plane wave

Multi-scale Material Parameter Identification Using LS-DYNA® and LS-OPT®

Energy Technology Data Exchange (ETDEWEB)

Stander, Nielen; Basudhar, Anirban; Basu, Ushnish; Gandikota, Imtiaz; Savic, Vesna; Sun, Xin; Choi, Kyoo Sil; Hu, Xiaohua; Pourboghrat, F.; Park, Taejoon; Mapar, Aboozar; Kumar, Shavan; Ghassemi-Armaki, Hassan; Abu-Farha, Fadi

2015-09-14

Test Ban Treaty of 1996 which banned surface testing of nuclear devices [1]. This had the effect that experimental work was reduced from large scale tests to multiscale experiments to provide material models with validation at different length scales. In the subsequent years industry realized that multi-scale modeling and simulation-based design were transferable to the design optimization of any structural system. Horstemeyer [1] lists a number of advantages of the use of multiscale modeling. Among these are: the reduction of product development time by alleviating costly trial-and-error iterations as well as the reduction of product costs through innovations in material, product and process designs. Multi-scale modeling can reduce the number of costly large scale experiments and can increase product quality by providing more accurate predictions. Research tends to be focussed on each particular length scale, which enhances accuracy in the long term. This paper serves as an introduction to the LS-OPT and LS-DYNA methodology for multi-scale modeling. It mainly focuses on an approach to integrate material identification using material models of different length scales. As an example, a multi-scale material identification strategy, consisting of a Crystal Plasticity (CP) material model and a homogenized State Variable (SV) model, is discussed and the parameter identification of the individual material models of different length scales is demonstrated. The paper concludes with thoughts on integrating the multi-scale methodology into the overall vehicle design.

Bayesian calibration of thermodynamic parameters for geochemical speciation modeling of cementitious materials

International Nuclear Information System (INIS)

Sarkar, S.; Kosson, D.S.; Mahadevan, S.; Meeussen, J.C.L.; Sloot, H. van der; Arnold, J.R.; Brown, K.G.

2012-01-01

Chemical equilibrium modeling of cementitious materials requires aqueous–solid equilibrium constants of the controlling mineral phases (K sp ) and the available concentrations of primary components. Inherent randomness of the input and model parameters, experimental measurement error, the assumptions and approximations required for numerical simulation, and inadequate knowledge of the chemical process contribute to uncertainty in model prediction. A numerical simulation framework is developed in this paper to assess uncertainty in K sp values used in geochemical speciation models. A Bayesian statistical method is used in combination with an efficient, adaptive Metropolis sampling technique to develop probability density functions for K sp values. One set of leaching experimental observations is used for calibration and another set is used for comparison to evaluate the applicability of the approach. The estimated probability distributions of K sp values can be used in Monte Carlo simulation to assess uncertainty in the behavior of aqueous–solid partitioning of constituents in cement-based materials.

Reference ranges of some haematological parameters in healthy ...

African Journals Online (AJOL)

Background: The haematological values of populations differ due to numerous factors. It is essential to establish the normal haematological values in every population to ensure appropriate interpretation of results in health and disease states. Materials and Methods: A total of 184 consenting apparently healthy adults (62 ...

Impact of Material and Architecture Model Parameters on the Failure of Woven Ceramic Matrix Composites (CMCs) via the Multiscale Generalized Method of Cells

Science.gov (United States)

Liu, Kuang C.; Arnold, Steven M.

2011-01-01

It is well known that failure of a material is a locally driven event. In the case of ceramic matrix composites (CMCs), significant variations in the microstructure of the composite exist and their significance on both deformation and life response need to be assessed. Examples of these variations include changes in the fiber tow shape, tow shifting/nesting and voids within and between tows. In the present work, the effects of many of these architectural parameters and material scatter of woven ceramic composite properties at the macroscale (woven RUC) will be studied to assess their sensitivity. The recently developed Multiscale Generalized Method of Cells methodology is used to determine the overall deformation response, proportional elastic limit (first matrix cracking), and failure under tensile loading conditions. The macroscale responses investigated illustrate the effect of architectural and material parameters on a single RUC representing a five harness satin weave fabric. Results shows that the most critical architectural parameter is weave void shape and content with other parameters being less in severity. Variation of the matrix material properties was also studied to illustrate the influence of the material variability on the overall features of the composite stress-strain response.

Advances in Functionalized Materials Research 2016

International Nuclear Information System (INIS)

Predoi, D.; Motelica-Heino, M.; Guegan, R.; Coustumer, L.Ph.

2016-01-01

In the last years, due to the rapid progress of technology, new materials at nano metric scale with special properties have become a flourishing field of research in materials science. The unique physicochemical properties of materials induced by various parameters such as mean size, shape, purity, crystallographic structure, and surface can generate effective solutions to challenging environmental and biomedical problems. As a result of this approach a large number of techniques were developed that enable obtaining novel materials at nano metric scale with specific and reproducible properties and parameters. Below will be highlighted studies on promising properties on the applicability of new materials that could lead to innovative applications in the medical field. Therefore, this special issue is focused on expected advances in the area of functionalized materials at nano metric scale. Due to multidisciplinarity of this topic, this special issue is comprised of a wide range of original research articles as well as review papers on the design and synthesis of functionalized nano materials, their structural, morphological, and biological characterization, and their potential uses in medical and environmental applications

Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters

Energy Technology Data Exchange (ETDEWEB)

Day-Lewis, Frederick David [US Geological Survey, Storrs, CT (United States); Singha, Kamini [Colorado School of Mines, Golden, CO (United States); Johnson, Timothy C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Haggerty, Roy [Oregon State Univ., Corvallis, OR (United States); Binley, Andrew [Lancaster Univ. (United Kingdom); Lane, John W. [US Geological Survey, Storrs, CT (United States)

2014-11-25

Mass transfer affects contaminant transport and is thought to control the efficiency of aquifer remediation at a number of sites within the Department of Energy (DOE) complex. An improved understanding of mass transfer is critical to meeting the enormous scientific and engineering challenges currently facing DOE. Informed design of site remedies and long-term stewardship of radionuclide-contaminated sites will require new cost-effective laboratory and field techniques to measure the parameters controlling mass transfer spatially and across a range of scales. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Including the NMR component, our revised study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3

Flexible and self-powered temperature-pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials.

Science.gov (United States)

Zhang, Fengjiao; Zang, Yaping; Huang, Dazhen; Di, Chong-an; Zhu, Daoben

2015-09-21

Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature-pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of pressure-sensing sensitivity of up to 28.9 kPa(-1). More importantly, these dual-parameter sensors can be self-powered with outstanding sensing performance. The excellent sensing properties of MFSOTE-based devices, together with their unique advantages of low cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

Structuring of material parameters in lithium niobate crystals with low-mass, high-energy ion radiation

Science.gov (United States)

Peithmann, K.; Eversheim, P.-D.; Goetze, J.; Haaks, M.; Hattermann, H.; Haubrich, S.; Hinterberger, F.; Jentjens, L.; Mader, W.; Raeth, N. L.; Schmid, H.; Zamani-Meymian, M.-R.; Maier, K.

2011-10-01

Ferroelectric lithium niobate crystals offer a great potential for applications in modern optics. To provide powerful optical components, tailoring of key material parameters, especially of the refractive index n and the ferroelectric domain landscape, is required. Irradiation of lithium niobate crystals with accelerated ions causes strong structured modifications in the material. The effects induced by low-mass, high-energy ions (such as 3He with 41 MeV, which are not implanted, but transmit through the entire crystal volume) are reviewed. Irradiation yields large changes of the refractive index Δn, improved domain engineering capability within the material along the ion track, and waveguiding structures. The periodic modification of Δn as well as the formation of periodically poled lithium niobate (PPLN) (supported by radiation damage) is described. Two-step knock-on displacement processes, 3He→Nb and 3He→O causing thermal spikes, are identified as origin for the material modifications.

Optimisation Of Cutting Parameters Of Composite Material Laser Cutting Process By Taguchi Method

Science.gov (United States)

Lokesh, S.; Niresh, J.; Neelakrishnan, S.; Rahul, S. P. Deepak

2018-03-01

The aim of this work is to develop a laser cutting process model that can predict the relationship between the process input parameters and resultant surface roughness, kerf width characteristics. The research conduct is based on the Design of Experiment (DOE) analysis. Response Surface Methodology (RSM) is used in this work. It is one of the most practical and most effective techniques to develop a process model. Even though RSM has been used for the optimization of the laser process, this research investigates laser cutting of materials like Composite wood (veneer)to be best circumstances of laser cutting using RSM process. The input parameters evaluated are focal length, power supply and cutting speed, the output responses being kerf width, surface roughness, temperature. To efficiently optimize and customize the kerf width and surface roughness characteristics, a machine laser cutting process model using Taguchi L9 orthogonal methodology was proposed.

Application of an improved model for the identification of material parameters

DEFF Research Database (Denmark)

Frederiksen, Per S.

1997-01-01

Elastic material constants of thick plates can be identified by combining a range of measured natural frequencies with an accurate numerical model for the theoretical predictions. To deal with thick plates, a model that takes transverse shear effects into account is necessary. Since modeling errors...... affect the estimates in a systematic way, an accurate numerical model is of primary importance. Compared to a model used previously, an improved more accurate plate model is studied here for the purpose of identification. This new advanced model is used to assess the systematic errors...

Parameter Estimation of Partial Differential Equation Models

KAUST Repository

Xun, Xiaolei

2013-09-01

Partial differential equation (PDE) models are commonly used to model complex dynamic systems in applied sciences such as biology and finance. The forms of these PDE models are usually proposed by experts based on their prior knowledge and understanding of the dynamic system. Parameters in PDE models often have interesting scientific interpretations, but their values are often unknown and need to be estimated from the measurements of the dynamic system in the presence of measurement errors. Most PDEs used in practice have no analytic solutions, and can only be solved with numerical methods. Currently, methods for estimating PDE parameters require repeatedly solving PDEs numerically under thousands of candidate parameter values, and thus the computational load is high. In this article, we propose two methods to estimate parameters in PDE models: a parameter cascading method and a Bayesian approach. In both methods, the underlying dynamic process modeled with the PDE model is represented via basis function expansion. For the parameter cascading method, we develop two nested levels of optimization to estimate the PDE parameters. For the Bayesian method, we develop a joint model for data and the PDE and develop a novel hierarchical model allowing us to employ Markov chain Monte Carlo (MCMC) techniques to make posterior inference. Simulation studies show that the Bayesian method and parameter cascading method are comparable, and both outperform other available methods in terms of estimation accuracy. The two methods are demonstrated by estimating parameters in a PDE model from long-range infrared light detection and ranging data. Supplementary materials for this article are available online. © 2013 American Statistical Association.

Moisture buffer capacity of different insulation materials

DEFF Research Database (Denmark)

Peuhkuri, Ruut Hannele; Rode, Carsten; Hansen, Kurt Kielsgaard

2004-01-01

. In the isothermal tests the material samples were exposed to the same change in the relative humidity of the ambient air on both sides, while the samples were exposed to variations in relative humidity only on the cold side in the non-isothermal tests. The results of these rather different measurement principles...... lead to more durable constructions. In this paper, a large range of very different thermal insulation materials have been tested in specially constructed laboratory facilities to determine their moisture buffer capacity. Both isothermal and nonisothermal experimental set-ups have been used...... are discussed, and different ways are presented how to determine the moisture buffer capacity of the materials using partly standard material parameters and partly parameters determined from the actual measurements. The results so far show that the determination of moisture buffer capacity is very sensitive...

Carbon nanotube scaffolds with controlled porosity as electromagnetic absorbing materials in the gigahertz range

Science.gov (United States)

González, M.; Crespo, M.; Baselga, J.; Pozuelo, J.

2016-05-01

Control of the microscopic structure of CNT nanocomposites allows modulation of the electromagnetic shielding in the gigahertz range. The porosity of CNT scaffolds has been controlled by two freezing protocols and a subsequent lyophilization step: fast freezing in liquid nitrogen and slow freezing at -20 °C. Mercury porosimetry shows that slowly frozen specimens present a more open pore size (100-150 μm) with a narrow distribution whereas specimens frozen rapidly show a smaller pore size and a heterogeneous distribution. 3D-scaffolds containing 3, 4, 6 and 7% CNT were infiltrated with epoxy and specimens with 2, 5 and 8 mm thicknesses were characterized in the GHz range. Samples with the highest pore size and porosity presented the lowest reflected power (about 30%) and the highest absorbed power (about 70%), which allows considering them as electromagnetic radiation absorbing materials.Control of the microscopic structure of CNT nanocomposites allows modulation of the electromagnetic shielding in the gigahertz range. The porosity of CNT scaffolds has been controlled by two freezing protocols and a subsequent lyophilization step: fast freezing in liquid nitrogen and slow freezing at -20 °C. Mercury porosimetry shows that slowly frozen specimens present a more open pore size (100-150 μm) with a narrow distribution whereas specimens frozen rapidly show a smaller pore size and a heterogeneous distribution. 3D-scaffolds containing 3, 4, 6 and 7% CNT were infiltrated with epoxy and specimens with 2, 5 and 8 mm thicknesses were characterized in the GHz range. Samples with the highest pore size and porosity presented the lowest reflected power (about 30%) and the highest absorbed power (about 70%), which allows considering them as electromagnetic radiation absorbing materials. Electronic supplementary information (ESI) available: Scheme of hydrogenated derivative of diglycidyl ether of bisphenol-A (HDGEBA) and m-xylylenediamine; X-ray diffractograms of pristine CNT

DRAGON solutions to the 3D transport benchmark over a range in parameter space

International Nuclear Information System (INIS)

Martin, Nicolas; Hebert, Alain; Marleau, Guy

2010-01-01

DRAGON solutions to the 'NEA suite of benchmarks for 3D transport methods and codes over a range in parameter space' are discussed in this paper. A description of the benchmark is first provided, followed by a detailed review of the different computational models used in the lattice code DRAGON. Two numerical methods were selected for generating the required quantities for the 729 configurations of this benchmark. First, S N calculations were performed using fully symmetric angular quadratures and high-order diamond differencing for spatial discretization. To compare S N results with those of another deterministic method, the method of characteristics (MoC) was also considered for this benchmark. Comparisons between reference solutions, S N and MoC results illustrate the advantages and drawbacks of each methods for this 3-D transport problem.

Test System for Thermoelectric Modules and Materials

Science.gov (United States)

Hejtmánek, J.; Knížek, K.; Švejda, V.; Horna, P.; Sikora, M.

2014-10-01

We present a design for a complex measuring device that enables its user to assess the parameters of power-generating thermoelectric modules (TEMs) (or bulk thermoelectric materials) under a wide range of temperatures ( T cold = 25°C to 90°C, T hot TEM, the actual heat flow through the module, and its mechanical load, which can be varied during the measurement. Key components of our testing setup are (i) a measuring chamber where the TEM/material is compressed between thermally shielded heating blocks equipped with a mechanical loading system and water-cooled copper-based cooler, (ii) an electrical load system, (iii) a type K thermocouple array connected to a data acquisition computer, and (iv) a thermostatic water-based cooling system with electronically controlled flow rate and temperature of cooling water. Our testing setup represents a useful tool able to assess, e.g., the thermoelectric parameters of newly developed TEMs and materials or to evaluate the thermoelectric parameters of commercially available modules and materials for comparison with values declared by the manufacturer.

Research on the Superheater Material Properties for USC Boiler with 700°C Steam Parameter

Science.gov (United States)

Chongbin, Wang; Xueyuan, Xu; Yufeng, Zhu; Yongqiang, Jin; Hui, Tong; Yu, Wang; Xiaoli, Lu

This paper discusses the materials' properties of superheater for 700°C USC boiler, including Sanicro25, HR6W, 617mod and 740H, and analyzes the range of applicable temperature of superheater made of different tubes, such as T91, T92, Super304H, TP310HCbN, Sanicro25, HR6W, 617Mod and 740H. In addition, some suggestions on the material selection have been proposed.

Statistical approach for uncertainty quantification of experimental modal model parameters

DEFF Research Database (Denmark)

Luczak, M.; Peeters, B.; Kahsin, M.

2014-01-01

Composite materials are widely used in manufacture of aerospace and wind energy structural components. These load carrying structures are subjected to dynamic time-varying loading conditions. Robust structural dynamics identification procedure impose tight constraints on the quality of modal models...... represent different complexity levels ranging from coupon, through sub-component up to fully assembled aerospace and wind energy structural components made of composite materials. The proposed method is demonstrated on two application cases of a small and large wind turbine blade........ This paper aims at a systematic approach for uncertainty quantification of the parameters of the modal models estimated from experimentally obtained data. Statistical analysis of modal parameters is implemented to derive an assessment of the entire modal model uncertainty measure. Investigated structures...

Photon albedo coefficients as functions of μ/Zeff parameter

Directory of Open Access Journals (Sweden)

Ljubenov Vladan L.

2013-01-01

Full Text Available This paper presents the results of the analyses of photon reflection from planar targets for normal photon incidence and for different shielding materials (water, concrete, aluminum, iron, and copper, in the range of the initial photon energies from 20 keV to 300 keV. Calculations of photon reflection parameters based on the results of Monte Carlo simulations of the photon transport have been performed using MCNP4C code. Integral reflection coefficients, presented as functions of the ratio of total cross-section of photons and effective atomic number of target material, show universal behaviour for all the analyzed shielding materials in the selected energy domain.

Tilted Magnetic Levitation Enables Measurement of the Complete Range of Densities of Materials with Low Magnetic Permeability.

Science.gov (United States)

Nemiroski, Alex; Soh, Siowling; Kwok, Sen Wai; Yu, Hai-Dong; Whitesides, George M

2016-02-03

Magnetic levitation (MagLev) of diamagnetic or weakly paramagnetic materials suspended in a paramagnetic solution in a magnetic field gradient provides a simple method to measure the density of small samples of solids or liquids. One major limitation of this method, thus far, has been an inability to measure or manipulate materials outside of a narrow range of densities (0.8 g/cm(3) MagLev"-to increase the range of densities that can be levitated magnetically. Tilting the MagLev device relative to the gravitational vector enables the magnetic force to be decreased (relative to the magnetic force) along the axis of measurement. This approach enables many practical measurements over the entire range of densities observed in matter at ambient conditions-from air bubbles (ρ ≈ 0) to osmium and iridium (ρ ≈ 23 g/cm(3)). The ability to levitate, simultaneously, objects with a broad range of different densities provides an operationally simple method that may find application to forensic science (e.g., for identifying the composition of miscellaneous objects or powders), industrial manufacturing (e.g., for quality control of parts), or resource-limited settings (e.g., for identifying and separating small particles of metals and alloys).

Correlation between some technological parameters and properties of composite material based on recycled tires and polymer binder

Science.gov (United States)

Plesuma, Renate; Malers, Laimonis

2015-04-01

The present article is dedicated to the determination of a possible connection between the composition, specific properties of the composite material and molding pressure as an important technological parameter. Apparent density, Shore C hardness, compressive modulus of elasticity and compressive stress at 10% deformation was determined for composite material samples. Definite formation conditions - varying molding pressure conditions at ambient temperature and corresponding relative air humiditywere realized. The results obtained showed a significant effect of molding pressure on the apparent density, mechanical properties of composite material as well as on the compressive stress change at a cyclic mode of loading. Some general regularities were determined - mechanical properties of the composite material, as well as values of Shore C hardness increases with an increase of molding pressure.

Effect of reference parameters and properties of materials for WWER-type fuel elements on their reliability

Energy Technology Data Exchange (ETDEWEB)

Bibilashvili, Yu K; Malachenko, L L; Medvedev, A V; Solyany, V I; Sukhanov, G I; Tonkov, V Yu

1987-05-01

Present approach to requirements for reference parameters and properties of materials for WWER-1000 fuel elements is presented as well as evaluation of their effects on fuel reliability. Some results of investigations with the aim of improving fuel element reliability in operational NPP conditions are discussed. 4 references, 7 figures, 3 tables.

Material characterization models and test methods for historic building materials

DEFF Research Database (Denmark)

Hansen, Tessa Kvist; Peuhkuri, Ruut Hannele; Møller, Eva B.

2017-01-01

Predictions of long term hygrothermal performance can be assessed by dynamic hygrothermal simulations, in which material parameters are crucial input. Material parameters for especially historic materials are often unknown; therefore, there is a need to determine important parameters, and simple...

Some relevant parameters for assessing fire hazards of combustible mine materials using laboratory scale experiments.

Science.gov (United States)

Litton, Charles D; Perera, Inoka E; Harteis, Samuel P; Teacoach, Kara A; DeRosa, Maria I; Thomas, Richard A; Smith, Alex C

2018-04-15

When combustible materials ignite and burn, the potential for fire growth and flame spread represents an obvious hazard, but during these processes of ignition and flaming, other life hazards present themselves and should be included to ensure an effective overall analysis of the relevant fire hazards. In particular, the gases and smoke produced both during the smoldering stages of fires leading to ignition and during the advanced flaming stages of a developing fire serve to contaminate the surrounding atmosphere, potentially producing elevated levels of toxicity and high levels of smoke obscuration that render the environment untenable. In underground mines, these hazards may be exacerbated by the existing forced ventilation that can carry the gases and smoke to locations far-removed from the fire location. Clearly, materials that require high temperatures (above 1400 K) and that exhibit low mass loss during thermal decomposition, or that require high heat fluxes or heat transfer rates to ignite represent less of a hazard than materials that decompose at low temperatures or ignite at low levels of heat flux. In order to define and quantify some possible parameters that can be used to assess these hazards, small-scale laboratory experiments were conducted in a number of configurations to measure: 1) the toxic gases and smoke produced both during non-flaming and flaming combustion; 2) mass loss rates as a function of temperature to determine ease of thermal decomposition; and 3) mass loss rates and times to ignition as a function of incident heat flux. This paper describes the experiments that were conducted, their results, and the development of a set of parameters that could possibly be used to assess the overall fire hazard of combustible materials using small scale laboratory experiments.

Irradiation-induced modification of the material parameters in magnesium-doped lithium niobate

International Nuclear Information System (INIS)

Jentjens, Lena

2010-01-01

In the framework of this thesis the material properties of lithium niobate are directedly influenced by the irradiation with 3 He ions with an energy of 40 MeV. In the first part the irradiation-induced material changes are intensively studied. Long-time stable changes of the refractive index are measured in the range of up to 6.10 -3 , which depend on the radiation dose and exhibit until now no saturation behaviour. Accompanied is this change by an also dose-dependent deformation as well as a brownish change of color of the crystals. Furthermore a by several orders of magnitude increased electrical dark- and photoconductivity, which depends on the ion dose and exhibits until now also no saturation behaviour. An effect independent on the ion dose is the reduction of the coercive field strength by about 10%. Furthermore it was stated the quantity of the effects not only depends on the absolute dose, but also on the irradiation direction in view of the crystallographic c-axis. The second part of this thesis deals with the generation of microscopic structures in lithium niobate. By an ion microbeam respectively a shiftable slit aperture the fabrication of refractive-index gratings is pursued. Grating with periodicity lengths in the range of 12-160 μm could until now be detected and promise in comparison with photorefractive gratings the advance of larger stability.

The ability to use FLEXPART in simulation of the long-range radioactive materials dispersed from nuclear power plants near Vietnam border

International Nuclear Information System (INIS)

Pham Kim Long; Pham Duy Hien; Nguyen Hao Quang; Do Xuan Anh; Duong Duc Thang; Doan Quang Tuyen

2016-01-01

FLEXPART is a Lagrangian transport and dispersion model suitable for the simulation of a large range of atmospheric transport processes. FLEXPART has been researched and applied in simulation of the long-range dispersion of radioactive materials. It can be applicable to the problem of radioactive materials released from the nuclear power plants impact on Vietnam. This report presents simulation of radioactive dispersion from the accident assumed Fangchenggang and Changjiang nuclear power plants in China with the FLEXPART, using meteorological data from the National Centers for Environmental Prediction (NCEP). The results of simulations and analyzing showed good applicability of FLEXPART for a long-range radioactive materials dispersion. The preliminary simulation results show that the impact of the radioactive material dispersion in Vietnam varies by the well-known characteristics of the monsoon of our country. Winter is the time when the dominant northeast winds up radioactive dispersion most towards our country, its sphere of influence extends from the Northeast (Quang Ninh) to North Central (Da Nang). (author)

Photoelectron angular distribution parameters for elements Z=55 to Z=100 in the photoelectron energy range 100-5000 eV

CERN Document Server

Trzhaskovskaya, M B; Yarzhemsky, V G

2002-01-01

Presented here are parameters of the angular distribution of photoelectrons along with the subshell photoionization cross sections for all atoms with 55<=Z<=100 and for atomic shells with binding energies lower than 2000 eV. The parameters are given for nine photoelectron energies in the range 100-5000 eV. Relativistic calculations have been carried out within the quadrupole approximation by the use of the central Dirac-Fock-Slater potential. The effect of the hole resulting in the atomic subshell after photoionization has been taken into account in the framework of the frozen orbital approximation.

Comparison of three methods reducing the beam parameter product of a laser diode stack for long range laser illumination applications

Science.gov (United States)

Lutz, Yves; Poyet, Jean-Michel; Metzger, Nicolas

2013-10-01

Laser diode stacks are interesting laser sources for active imaging illuminators. They allow the accumulation of large amounts of energy in multi-pulse mode, which is well suited for long-range image recording. Even when laser diode stacks are equipped with fast-axis collimation (FAC) and slow-axis collimation (SAC) microlenses, their beam parameter product (BPP) are not compatible with a direct use in highly efficient and compact illuminators. This is particularly true when narrow divergences are required such as for long range applications. To overcome these difficulties, we conducted investigations in three different ways. A first near infrared illuminator based on the use of conductively cooled mini-bars was designed, realized and successfully tested during outdoor experimentations. This custom specified stack was then replaced in a second step by an off-the-shelf FAC + SAC micro lensed stack where the brightness was increased by polarization overlapping. The third method still based on a commercial laser diode stack uses a non imaging optical shaping principle resulting in a virtually restacked laser source with enhanced beam parameters. This low cost, efficient and low alignment sensitivity beam shaping method allows obtaining a compact and high performance laser diode illuminator for long range active imaging applications. The three methods are presented and compared in this paper.

Exact Solutions of the Hierarchical Korteweg-de Vries Equation of Micro structured Granular Materials

International Nuclear Information System (INIS)

Abourabia, A.M.; El-Danaf, T.S.; Morad, A.M.

2008-01-01

The problem under consideration are related to wave propagation in micro structured materials, characterized by higher-order nonlinear and higher-order dispersive effects; particularly, the wave propagation in dilatant granular materials. In the present paper the model equation is solved analytically by exact method called Jacobi elliptic method. The types of solutions are defined and discussed over a wide range of material parameters (two dispersion parameters and one microstructure parameter). The dispersion properties and the relation between group and phase velocities of the model equation are studied. The diagrams are drawn to illustrate the physical properties of the exact solutions

Synthesis of Algorithm for Range Measurement Equipment to Track Maneuvering Aircraft Using Data on Its Dynamic and Kinematic Parameters

Science.gov (United States)

Pudovkin, A. P.; Panasyuk, Yu N.; Danilov, S. N.; Moskvitin, S. P.

2018-05-01

The problem of improving automated air traffic control systems is considered through the example of the operation algorithm synthesis for a range measurement channel to track the aircraft, using its kinematic and dynamic parameters. The choice of the state and observation models has been justified, the computer simulations have been performed and the results of the investigated algorithms have been obtained.

Evaluation of fundamental parameters method for biological materials and soil analysis by energy dispersive x-ray spectrometry

Energy Technology Data Exchange (ETDEWEB)

Holynska, B; Muia, L M; Maina, D M

1987-01-01

Two methods of determination of trace elements in plant materials, viz. the fundamental parameters method (FPM) and the empirical method with the use of standard samples, were compared. Hay CRM and fresh tea leaves were used in measurements. Good agreement was achieved for the determination of a number of elements by both methods. Also Soil-7 Certified Reference Material (CRM) was analysed using emission-transmission method for absorption correction and FPM for concentration determination. The agreement with CRM was found to be reasonably good for several elements.

Effect of primary and secondary parameters on analytical estimation of effective thermal conductivity of two phase materials using unit cell approach

Science.gov (United States)

S, Chidambara Raja; P, Karthikeyan; Kumaraswamidhas, L. A.; M, Ramu

2018-05-01

Most of the thermal design systems involve two phase materials and analysis of such systems requires detailed understanding of the thermal characteristics of the two phase material. This article aimed to develop geometry dependent unit cell approach model by considering the effects of all primary parameters (conductivity ratio and concentration) and secondary parameters (geometry, contact resistance, natural convection, Knudsen and radiation) for the estimation of effective thermal conductivity of two-phase materials. The analytical equations have been formulated based on isotherm approach for 2-D and 3-D spatially periodic medium. The developed models are validated with standard models and suited for all kind of operating conditions. The results have shown substantial improvement compared to the existing models and are in good agreement with the experimental data.

The effect of reference parameters and properties of materials for WWER-type fuel elements on their reliability

International Nuclear Information System (INIS)

Bibilashvili, Yu.K.; Malachenko, L.L.; Medvedev, A.V.; Solyany, V.I.; Sukhanov, G.I.; Tonkov, V.Yu.

1987-01-01

Present approach to requirements for reference parameters and properties of materials for WWER-1000 fuel elements is presented as well as evaluation of their effects on fuel reliability. Some results of investigations with the aim of improving fuel element reliability in operational NPP conditions are discussed. (author)

Ultra-Weak Fiber Bragg Grating Sensing Network Coated with Sensitive Material for Multi-Parameter Measurements

OpenAIRE

Bai, Wei; Yang, Minghong; Hu, Chenyuan; Dai, Jixiang; Zhong, Xuexiang; Huang, Shuai; Wang, Gaopeng

2017-01-01

A multi-parameter measurement system based on ultra-weak fiber Bragg grating (UFBG) array with sensitive material was proposed and experimentally demonstrated. The UFBG array interrogation principle is time division multiplex technology with two semiconductor optical amplifiers as timing units. Experimental results showed that the performance of the proposed UFBG system is almost equal to that of traditional FBG, while the UFBG array system has obvious superiority with potential multiplexing ...

On the number of free energy extremums of a solid solution with two long-range order parameters

International Nuclear Information System (INIS)

Dateshidze, N.A.; Ratishvili, I.G.

1977-01-01

The free energy of ordering f.c.c. lattice solid solution is investigated. The ordering is regarded as homogeneous in the whole bulk of the crystal (i.e. resistant towards formation of antiphase domains). It is described by one of the appropriate distribution functions which contains two long-range order parameters. The calculations have revealed the extrema of the free energy function, and their shape and behaviour upon variations of temperature are analyzed. It is shown that under certain circumstances the system can display more than one minimum of free energy within the ordered phase

Parameters for scale-up of lethal microwave treatment to eradicate cerambycid larvae infesting solid wood packing materials

Science.gov (United States)

Mary R. Fleming; John J. Janowiak; Joseph Kearns; Jeffrey E. Shield; Rustum Roy; Dinesh K. Agrawal; Leah S. Bauer; Kelli Hoover

2004-01-01

The use of microwave irradiation to eradicate insects infesting wood used to manufacture packing materials such as pallets and crateswas evaluated. The focus of this preliminary studywas to determinewhich microwave parameters, including chamber-volume to sample-volumeratios,variations ofpower and time, and energydensity (total microwavepower/woodvolume), affect the...

Evaluation of fundamental parameters method for biological materials and soil analysis by energy dispersive x-ray spectrometry

International Nuclear Information System (INIS)

Holynska, B.; Muia, L.M.; Maina, D.M.

1987-01-01

Two methods of determination of trace elements in plant materials, viz. the fundamental parameters method (FPM) and the empirical method with the use of standard samples, were compared. Hay CRM and fresh tea leaves were used in measurements. Good agreement was achieved for the determination of a number of elements by both methods. Also Soil-7 Certified Reference Material (CRM) was analysed using emission-transmission method for absorption correction and FPM for concentration determination. The agreement with CRM was found to be reasonably good for several elements. (author)

IEP as a parameter characterizing the pH-dependent surface charging of materials other than metal oxides.

Science.gov (United States)

Kosmulski, Marek

2012-01-01

The numerical values of points of zero charge (PZC, obtained by potentiometric titration) and of isoelectric points (IEP) of various materials reported in the literature have been analyzed. In sets of results reported for the same chemical compound (corresponding to certain chemical formula and crystallographic structure), the IEP are relatively consistent. In contrast, in materials other than metal oxides, the sets of PZC are inconsistent. In view of the inconsistence in the sets of PZC and of the discrepancies between PZC and IEP reported for the same material, it seems that IEP is more suitable than PZC as the unique number characterizing the pH-dependent surface charging of materials other than metal oxides. The present approach is opposite to the usual approach, in which the PZC and IEP are considered as two equally important parameters characterizing the pH-dependent surface charging of materials other than metal oxides. Copyright © 2012 Elsevier B.V. All rights reserved.

Prediction of dosage-based parameters from the puff dispersion of airborne materials in urban environments using the CFD-RANS methodology

Science.gov (United States)

Efthimiou, G. C.; Andronopoulos, S.; Bartzis, J. G.

2018-02-01

One of the key issues of recent research on the dispersion inside complex urban environments is the ability to predict dosage-based parameters from the puff release of an airborne material from a point source in the atmospheric boundary layer inside the built-up area. The present work addresses the question of whether the computational fluid dynamics (CFD)-Reynolds-averaged Navier-Stokes (RANS) methodology can be used to predict ensemble-average dosage-based parameters that are related with the puff dispersion. RANS simulations with the ADREA-HF code were, therefore, performed, where a single puff was released in each case. The present method is validated against the data sets from two wind-tunnel experiments. In each experiment, more than 200 puffs were released from which ensemble-averaged dosage-based parameters were calculated and compared to the model's predictions. The performance of the model was evaluated using scatter plots and three validation metrics: fractional bias, normalized mean square error, and factor of two. The model presented a better performance for the temporal parameters (i.e., ensemble-average times of puff arrival, peak, leaving, duration, ascent, and descent) than for the ensemble-average dosage and peak concentration. The majority of the obtained values of validation metrics were inside established acceptance limits. Based on the obtained model performance indices, the CFD-RANS methodology as implemented in the code ADREA-HF is able to predict the ensemble-average temporal quantities related to transient emissions of airborne material in urban areas within the range of the model performance acceptance criteria established in the literature. The CFD-RANS methodology as implemented in the code ADREA-HF is also able to predict the ensemble-average dosage, but the dosage results should be treated with some caution; as in one case, the observed ensemble-average dosage was under-estimated slightly more than the acceptance criteria. Ensemble

Neutron spectrum perturbations due to scattering materials and their effect on the average neutron energy, the spectral index, and the hardness parameter

International Nuclear Information System (INIS)

Wright, H.L.; Meason, J.L.; Wolf, M.; Harvey, J.T.

1976-01-01

Measurements have been performed on the perturbing effect of a number of scattering materials by the 'free-field' neutron leakage spectrum from a Godiva Type Critical Assembly (White Sands Missile Range Fast Burst Reactor). The results of these measurements are interpreted in relation to some of the general parameters characterizing a neutron environment, namely, the average neutron energy >10 KeV, the spectral index and the hardness parameter. Three neutron spectrum measurements have been performed, each under different experimental configurations of scattering materials. Results from these measurements show the following with relation to the spectral index: (1) The neutron environment on the core surface and at 12-inches from the core surface (free-field) yield a spectral index of 6.8, (2) The neutron environment behind a 4.75-inch Plexiglas plate yield 4.6 for the spectral index and (3) The neutron environment behind a 2-inch aluminum plate yield 6.7 for the spectral index. It is concluded that the core surface and the 12-inch from core surface neutron environment are identical with the 'free-field' neutron environment at 20-inches when considering only those neutrons with energy >10 KeV. On the other hand, it appears that the 4.75 inches of Plexiglas severely perturbs the 'free-field' neutron environment, i.e., a much harder neutron spectrum >10 KeV. In the situation where 2-inches of aluminum is used as the perturbing medium, essentially no change in the neutron spectrum >10 KeV is noted

Data collection handbook to support modeling the impacts of radioactive material in soil

International Nuclear Information System (INIS)

Yu, C.; Cheng, J.J.; Jones, L.G.; Wang, Y.Y.; Faillace, E.; Loureiro, C.; Chia, Y.P.

1993-04-01

A pathway analysis computer code called RESRAD has been developed for implementing US Department of Energy Residual Radioactive Material Guidelines. Hydrogeological, meteorological, geochemical, geometrical (size, area, depth), and material-related (soil, concrete) parameters are used in the RESRAD code. This handbook discusses parameter definitions, typical ranges, variations, measurement methodologies, and input screen locations. Although this handbook was developed primarily to support the application of RESRAD, the discussions and values are valid for other model applications

Data collection handbook to support modeling the impacts of radioactive material in soil

Energy Technology Data Exchange (ETDEWEB)

Yu, C.; Cheng, J.J.; Jones, L.G.; Wang, Y.Y.; Faillace, E. [Argonne National Lab., IL (United States). Environmental Assessment and Information Sciences Div.; Loureiro, C. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Escola de Engenharia; Chia, Y.P. [National Taiwan Univ., Taipei (Taiwan, Province of China). Dept. of Geology

1993-04-01

A pathway analysis computer code called RESRAD has been developed for implementing US Department of Energy Residual Radioactive Material Guidelines. Hydrogeological, meteorological, geochemical, geometrical (size, area, depth), and material-related (soil, concrete) parameters are used in the RESRAD code. This handbook discusses parameter definitions, typical ranges, variations, measurement methodologies, and input screen locations. Although this handbook was developed primarily to support the application of RESRAD, the discussions and values are valid for other model applications.

Wide-range measurement of thermal effusivity using molybdenum thin film with low thermal conductivity for thermal microscopes

Science.gov (United States)

Miyake, Shugo; Matsui, Genzou; Ohta, Hiromichi; Hatori, Kimihito; Taguchi, Kohei; Yamamoto, Suguru

2017-07-01

Thermal microscopes are a useful technology to investigate the spatial distribution of the thermal transport properties of various materials. However, for high thermal effusivity materials, the estimated values of thermophysical parameters based on the conventional 1D heat flow model are known to be higher than the values of materials in the literature. Here, we present a new procedure to solve the problem which calculates the theoretical temperature response with the 3D heat flow and measures reference materials which involve known values of thermal effusivity and heat capacity. In general, a complicated numerical iterative method and many thermophysical parameters are required for the calculation in the 3D heat flow model. Here, we devised a simple procedure by using a molybdenum (Mo) thin film with low thermal conductivity on the sample surface, enabling us to measure over a wide thermal effusivity range for various materials.

Long-range propagation of plasmon and phonon polaritons in hyperbolic-metamaterial waveguides

Science.gov (United States)

Babicheva, Viktoriia E.

2017-12-01

We study photonic multilayer waveguides that include layers of materials and metamaterials with a hyperbolic dispersion (HMM). We consider the long-range propagation of plasmon and phonon polaritons at the dielectric-HMM interface in different waveguide geometries (single boundary or different layers of symmetric cladding). In contrast to the traditional analysis of geometrical parameters, we make an emphasis on the optical properties of constituent materials: solving dispersion equations, we analyze how dielectric and HMM permittivities affect propagation length and mode size of waveguide eigenmodes. We derive figures of merit that should be used for each waveguide in a broad range of permittivity values as well as compare them with plasmonic waveguides. We show that the conventional plasmonic quality factor, which is the ratio of real to imaginary parts of permittivity, is not applicable to the case of waveguides with complex structure. Both telecommunication wavelengths and mid-infrared spectral ranges are of interest considering recent advances in van der Waals materials, such as hexagonal boron nitride. We evaluate the performance of the waveguides with hexagonal boron nitride in the range where it possesses hyperbolic dispersion (wavelength 6.3-7.3 μm), and we show that these waveguides with natural hyperbolic properties have higher propagation lengths than metal-based HMM waveguides.

Comprehensive reference ranges for hematology and clinical chemistry laboratory parameters derived from normal Nigerian adults.

Science.gov (United States)

Miri-Dashe, Timzing; Osawe, Sophia; Tokdung, Monday; Daniel, Monday Tokdung Nenbammun; Daniel, Nenbammun; Choji, Rahila Pam; Mamman, Ille; Deme, Kurt; Damulak, Dapus; Abimiku, Alash'le

2014-01-01

Interpretation of laboratory test results with appropriate diagnostic accuracy requires reference or cutoff values. This study is a comprehensive determination of reference values for hematology and clinical chemistry in apparently healthy voluntary non-remunerated blood donors and pregnant women. Consented clients were clinically screened and counseled before testing for HIV, Hepatitis B, Hepatitis C and Syphilis. Standard national blood donors' questionnaire was administered to consented blood donors. Blood from qualified volunteers was used for measurement of complete hematology and chemistry parameters. Blood samples were analyzed from a total of 383 participants, 124 (32.4%) males, 125 (32.6%) non-pregnant females and 134 pregnant females (35.2%) with a mean age of 31 years. Our results showed that the red blood cells count (RBC), Hemoglobin (HB) and Hematocrit (HCT) had significant gender difference (p = 0.000) but not for total white blood count (p>0.05) which was only significantly higher in pregnant verses non-pregnant women (p = 0.000). Hemoglobin and Hematocrit values were lower in pregnancy (P = 0.000). Platelets were significantly higher in females than men (p = 0.001) but lower in pregnant women (p =  .001) with marked difference in gestational period. For clinical chemistry parameters, there was no significant difference for sodium, potassium and chloride (p>0.05) but gender difference exists for Bicarbonate (HCO3), Urea nitrogen, Creatinine as well as the lipids (pchemistry parameters between pregnant and non-pregnant women in this study (p0.05). Hematological and Clinical Chemistry reference ranges established in this study showed significant gender differences. Pregnant women also differed from non-pregnant females and during pregnancy. This is the first of such comprehensive study to establish reference values among adult Nigerians and difference observed underscore the need to establish reference values for different populations.

Impact of structural parameters on the radon exhalation of building materials: Preliminary study

International Nuclear Information System (INIS)

Roelofs, L.M.M.

1993-01-01

Samples of mortar and sand-lime pieces with different percentages of fly ash are hardened at different relative humidities. The porosity distribution, the moisture and the radon exhalation of these samples are determined. Based on the data of the above-mentioned analyses, the thickness of the adsorbed water layer in the water-filled pores is estimated. The correlation between the structural parameters and the radon exhalation is investigated. If the radon exhalation process can be modelled, the radiation risk of applying fly ash in building materials can be controlled or reduced. The results do not yet show a clear indication. The applied methods have to be considered in more detail

Quality by design for herbal drugs: a feedforward control strategy and an approach to define the acceptable ranges of critical quality attributes.

Science.gov (United States)

Yan, Binjun; Li, Yao; Guo, Zhengtai; Qu, Haibin

2014-01-01

The concept of quality by design (QbD) has been widely accepted and applied in the pharmaceutical manufacturing industry. There are still two key issues to be addressed in the implementation of QbD for herbal drugs. The first issue is the quality variation of herbal raw materials and the second issue is the difficulty in defining the acceptable ranges of critical quality attributes (CQAs). To propose a feedforward control strategy and a method for defining the acceptable ranges of CQAs for the two issues. In the case study of the ethanol precipitation process of Danshen (Radix Salvia miltiorrhiza) injection, regression models linking input material attributes and process parameters to CQAs were built first and an optimisation model for calculating the best process parameters according to the input materials was established. Then, the feasible material space was defined and the acceptable ranges of CQAs for the previous process were determined. In the case study, satisfactory regression models were built with cross-validated regression coefficients (Q(2) ) all above 91 %. The feedforward control strategy was applied successfully to compensate the quality variation of the input materials, which was able to control the CQAs in the 90-110 % ranges of the desired values. In addition, the feasible material space for the ethanol precipitation process was built successfully, which showed the acceptable ranges of the CQAs for the concentration process. The proposed methodology can help to promote the implementation of QbD for herbal drugs. Copyright © 2013 John Wiley & Sons, Ltd.

Estimating material parameters of a structurally based constitutive relation for skin mechanics

KAUST Repository

Jor, Jessica W. Y.

2010-11-25

This paper presents a structurally based modeling framework to characterize the structure-function relation in skin tissues, based upon biaxial tensile experiments performed in vitro on porcine skin. Equi-axial deformations were imposed by stretching circular skin specimens uniformly along twelve directions, and the resultant loads at the membrane attachment points were measured. Displacement fields at each deformation step were tracked using an image 2D cross-correlation technique. A modeling framework was developed to simulate the experiments, whereby measured forces were applied to finite element models that were created to represent the geometry and structure of the tissue samples. Parameters of a structurally based constitutive relation were then identified using nonlinear optimization. Results showed that the ground matrix stiffness ranged from 5 to 32 kPa, fiber orientation mean from 2 to 13. from the torso midline, fiber undulation mean from 1.04 to 1.34 and collagen fiber stiffness from 48 to 366 MPa. It was concluded that the objective function was highly sensitive to the mean orientation and that a priori information about fiber orientation mean was important for the reliable identification of constitutive parameters. © Springer-Verlag 2010.

Final Report: Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters

Energy Technology Data Exchange (ETDEWEB)

Haggerty, Roy [Oregon State Univ., Corvallis, OR (United States); Day-Lewis, Fred [U.S. Geological Survey, Storrs, CT (United States); Singha, Kamini [Colorado School of Mines, Golden, CO (United States); Johnson, Timothy [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Binley, Andrew [Lancaster Univ. (United Kingdom); Lane, John [U.S. Geological Survey, Storrs, CT (United States)

2014-03-20

Mass transfer affects contaminant transport and is thought to control the efficiency of aquifer remediation at a number of sites within the Department of Energy (DOE) complex. An improved understanding of mass transfer is critical to meeting the enormous scientific and engineering challenges currently facing DOE. Informed design of site remedies and long-term stewardship of radionuclide-contaminated sites will require new cost-effective laboratory and field techniques to measure the parameters controlling mass transfer spatially and across a range of scales. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Including the NMR component, our revised study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3

Contribution to the determination of the neutronic parameters uncertainties of a compact heterogeneous core: the material testing Jules Horowitz reactor

International Nuclear Information System (INIS)

Di Salvo, J.

2002-01-01

The design studies of the future Material Testing Reactor Jules Horowitz require the development of an adapted neutronic calculation route. To guarantee good accuracy and save time cost, some approximations with deterministic modelling (APOLLO2 / CRONOS2) are needed. As no relevant integral experiments are yet available to ensure the accuracy of the calculation, the results need to be validated by a rigorous methodical approach, which is based on comparison against numerical benchmarks (Monte Carlo TRIPOLI4 code). In order to complete the validation results, sensitivity coefficients of main neutronic parameters to nuclear data are very useful to get an estimate of the final uncertainty on the calculation. Unfortunately, most of covariance information is missing in the recent evaluated files such as JEF-2.2. To generate missing covariance matrices, a method based on the comparison of different independent evaluations is used in this study. Special attention is paid to the determination of sensitivity coefficients, using perturbation methods and direct calculations. This study points out the importance of the non-diagonal elements of the covariance matrices as well as the neutron capture cross section uncertainty of the 27Al in the thermal range. In complement to uncertainty studies, it will be still necessary to obtain integral experimental validation of the Jules Horowitz Reactor neutronic parameters calculations. (author)

Factors affecting the laser processing of wood, 2: Effects of material parameters on machinability

International Nuclear Information System (INIS)

Arai, T.; Hayashi, D.

1994-01-01

Material parameters of wood were investigated. Factors relating to the workpiece include cutting direction, specific gravity, and components of the wood such as resin-like materials. Also studies of the effects of irregular tissue on machinability were made. The interactions between laser beam and materials are often greatly complex. They depend on the characteristics of the laser beam, the thermal constants of the woods, and the optical surface properties of the woods. Therefore, high quality beam mode and carefully selected materials were used. The following laser cutting properties became clear after studying the experimental results. Slow speed cutting and softwoods make slight differences, regarding cutting section and fiber direction. However, it can beconsidered that there is not very much change except in cross-section. Because of the high power density of laser, cutting speed makes no big difference. The irregular tissue of wood cannot maintain normal cutting speed and accuracy. The factor of genuine density eta, which is thought to be entirely independent of each specific gravity, is definedas the concept of density in general. It can be obtained by applying a simple rule, that is, the eta is the ratio of r(u)/rho(s) where rho(s) is the wood substance as the characteristic value of wood, and r(u)is specific gravity. An experimental formula shows that the depth of cut decreases in proportion to the value of eta. However, in the strict sense of the word, data of wood material as a natural resources mustbe treated qualitatively, because there are deviations from regularity due to various reasons. (author)

Flexible and self-powered temperature-pressure dual-parameter sensors using microstructure-frame-supported organic thermoelectric materials

Science.gov (United States)

Zhang, Fengjiao; Zang, Yaping; Huang, Dazhen; di, Chong-An; Zhu, Daoben

2015-09-01

Skin-like temperature- and pressure-sensing capabilities are essential features for the next generation of artificial intelligent products. Previous studies of e-skin and smart elements have focused on flexible pressure sensors, whereas the simultaneous and sensitive detection of temperature and pressure with a single device remains a challenge. Here we report developing flexible dual-parameter temperature-pressure sensors based on microstructure-frame-supported organic thermoelectric (MFSOTE) materials. The effective transduction of temperature and pressure stimuli into two independent electrical signals permits the instantaneous sensing of temperature and pressure with an accurate temperature resolution of cost and large-area fabrication, make MFSOTE materials possess promising applications in e-skin and health-monitoring elements.

Evaluation of Dielectric-Barrier-Discharge Actuator Substrate Materials

Science.gov (United States)

Wilkinson, Stephen P.; Siochi, Emilie J.; Sauti, Godfrey; Xu, Tian-Bing; Meador, Mary Ann; Guo, Haiquan

2014-01-01

A key, enabling element of a dielectric barrier discharge (DBD) actuator is the dielectric substrate material. While various investigators have studied the performance of different homogeneous materials, most often in the context of related DBD experiments, fundamental studies focused solely on the dielectric materials have received less attention. The purpose of this study was to conduct an experimental assessment of the body-force-generating performance of a wide range of dielectric materials in search of opportunities to improve DBD actuator performance. Materials studied included commonly available plastics and glasses as well as a custom-fabricated polyimide aerogel. Diagnostics included static induced thrust, electrical circuit parameters for 2D surface discharges and 1D volume discharges, and dielectric material properties. Lumped-parameter circuit simulations for the 1D case were conducted showing good correspondence to experimental data provided that stray capacitances are included. The effect of atmospheric humidity on DBD performance was studied showing a large influence on thrust. The main conclusion is that for homogeneous, dielectric materials at forcing voltages less than that required for streamer formation, the material chemical composition appears to have no effect on body force generation when actuator impedance is properly accounted for.

THz characterization of hydrated and anhydrous materials

Science.gov (United States)

Sokolnikov, Andre

2011-06-01

The characterization of anhydrous and hydrated forms of materials is of great importance to science and industry. Water content poses difficulties for successful identification of the material structure by THz radiation. However, biological tissues and hydrated forms of nonorganic substances still may be investigated by THz radiation. This paper outlines the range of possibilities of the above characterization, as well as provides analysis of the physical mechanism that allows or prevents penetration of THz waves through the substance. THz-TDS is used to measure the parameters of the characterization of anhydrous and hydrated forms of organic and nonorganic samples. Mathematical methods (such as prediction models of time-series analysis) are used to help identifying the absorption coefficient and other parameters of interest. The discovered dependencies allow designing techniques for material identification/characterization (e.g. of drugs, explosives, etc. that may have water content). The results are provided.

Investigation of ellipsometric parameters of 2D microrough surfaces by FDTD.

Science.gov (United States)

Qiu, J; Ran, D F; Liu, Y B; Liu, L H

2016-07-10

Ellipsometry is a powerful method for measuring the optical constants of materials and is very sensitive to surface roughness. In previous ellipsometric measurement of optical constants of solid materials with rough surfaces, researchers frequently used effective medium approximation (EMA) with roughness already known to fit the complex refractive index of the material. However, the ignored correlation length, the other important parameter of rough surfaces, will definitely result in fitting errors. Hence it is necessary to consider the influence of surface roughness and correlation length on the ellipsometric parameters Δ (phase difference) and Ψ (azimuth) characterizing practical systems. In this paper, the influence of roughness of two-dimensional randomly microrough surfaces (relative roughness σ/λ ranges from 0.001 to 0.025) of silicon on ellipsometric parameters was simulated by the finite-difference time-domain method which was validated with experimental results. The effects of incident angle, relative roughness, and correlation length were numerically investigated for two-dimensional Gaussian distributed randomly microrough surfaces, respectively. The simulated results showed that compared with the smooth surface, only tiny changes of the ellipsometric parameter Δ could be observed for microrough silicon surface in the vicinity of the Brewster angle, but obviously changes of Ψ occur especially in the vicinity of the Brewster angle. More differences between the ellipsometric parameters of the rough surface and smooth surface can been seen especially in the vicinity of the Brewster angle as the relative roughness σ/λ increases or correlation length τ decreases. The results reveal that when we measure the optical constants of solid materials by ellipsometry, the smaller roughness, larger correlation length and larger incident wavelength will lead to the higher precision of measurements.

Identification of material parameters for plasticity models: A comparative study on the finite element model updating and the virtual fields method

Science.gov (United States)

Martins, J. M. P.; Thuillier, S.; Andrade-Campos, A.

2018-05-01

The identification of material parameters, for a given constitutive model, can be seen as the first step before any practical application. In the last years, the field of material parameters identification received an important boost with the development of full-field measurement techniques, such as Digital Image Correlation. These techniques enable the use of heterogeneous displacement/strain fields, which contain more information than the classical homogeneous tests. Consequently, different techniques have been developed to extract material parameters from full-field measurements. In this study, two of these techniques are addressed, the Finite Element Model Updating (FEMU) and the Virtual Fields Method (VFM). The main idea behind FEMU is to update the parameters of a constitutive model implemented in a finite element model until both numerical and experimental results match, whereas VFM makes use of the Principle of Virtual Work and does not require any finite element simulation. Though both techniques proved their feasibility in linear and non-linear constitutive models, it is rather difficult to rank their robustness in plasticity. The purpose of this work is to perform a comparative study in the case of elasto-plastic models. Details concerning the implementation of each strategy are presented. Moreover, a dedicated code for VFM within a large strain framework is developed. The reconstruction of the stress field is performed through a user subroutine. A heterogeneous tensile test is considered to compare FEMU and VFM strategies.

ADVANTG An Automated Variance Reduction Parameter Generator, Rev. 1

Energy Technology Data Exchange (ETDEWEB)

Mosher, Scott W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Johnson, Seth R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bevill, Aaron M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ibrahim, Ahmad M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Daily, Charles R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Evans, Thomas M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wagner, John C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Johnson, Jeffrey O. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Grove, Robert E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2015-08-01

The primary objective of ADVANTG is to reduce both the user effort and the computational time required to obtain accurate and precise tally estimates across a broad range of challenging transport applications. ADVANTG has been applied to simulations of real-world radiation shielding, detection, and neutron activation problems. Examples of shielding applications include material damage and dose rate analyses of the Oak Ridge National Laboratory (ORNL) Spallation Neutron Source and High Flux Isotope Reactor (Risner and Blakeman 2013) and the ITER Tokamak (Ibrahim et al. 2011). ADVANTG has been applied to a suite of radiation detection, safeguards, and special nuclear material movement detection test problems (Shaver et al. 2011). ADVANTG has also been used in the prediction of activation rates within light water reactor facilities (Pantelias and Mosher 2013). In these projects, ADVANTG was demonstrated to significantly increase the tally figure of merit (FOM) relative to an analog MCNP simulation. The ADVANTG-generated parameters were also shown to be more effective than manually generated geometry splitting parameters.

Optimized cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials

International Nuclear Information System (INIS)

Yu Zhenzhong; Feng Yijun; Xu Xiaofei; Zhao Junming; Jiang Tian

2011-01-01

We present optimized design of cylindrical invisibility cloak with minimum layers of non-magnetic isotropic materials. Through an optimization procedure based on genetic algorithm, simpler cloak structure and more realizable material parameters can be achieved with better cloak performance than that of an ideal non-magnetic cloak with a reduced set of parameters. We demonstrate that a cloak shell with only five layers of two normal materials can result in an average 20 dB reduction in the scattering width for all directions when covering the inner conducting cylinder with the cloak. The optimized design can substantially simplify the realization of the invisibility cloak, especially in the optical range.

Identifying the effects of parameter uncertainty on the reliability of riverbank stability modelling

Science.gov (United States)

Samadi, A.; Amiri-Tokaldany, E.; Darby, S. E.

2009-05-01

Bank retreat is a key process in fluvial dynamics affecting a wide range of physical, ecological and socioeconomic issues in the fluvial environment. To predict the undesirable effects of bank retreat and to inform effective measures to prevent it, a wide range of bank stability models have been presented in the literature. These models typically express bank stability by defining a factor of safety as the ratio of driving and resisting forces acting on the incipient failure block. These forces are affected by a range of controlling factors that include such aspects as the bank profile (bank height and angle), the geotechnical properties of the bank materials, as well as the hydrological status of the riverbanks. In this paper we evaluate the extent to which uncertainties in the parameterization of these controlling factors feed through to influence the reliability of the resulting bank stability estimate. This is achieved by employing a simple model of riverbank stability with respect to planar failure (which is the most common type of bank stability model) in a series of sensitivity tests and Monte Carlo analyses to identify, for each model parameter, the range of values that induce significant changes in the simulated factor of safety. These identified parameter value ranges are compared to empirically derived parameter uncertainties to determine whether they are likely to confound the reliability of the resulting bank stability calculations. Our results show that parameter uncertainties are typically high enough that the likelihood of generating unreliable predictions is typically very high (> ˜ 80% for predictions requiring a precision of < ± 15%). Because parameter uncertainties are derived primarily from the natural variability of the parameters, rather than measurement errors, much more careful attention should be paid to field sampling strategies, such that the parameter uncertainties and consequent prediction unreliabilities can be quantified more

Production and electrical parameters of La /SUB 1-x/ Ca /SUB x/ Cr /SUB 1-y/ Ni /SUB y/ O3 (x ranging from 0-0.3; y ranging from 0-1)

International Nuclear Information System (INIS)

Kononyuk, I.F.; Surmach, N.G.; Tolochko, S.P.

1986-01-01

This paper deals with the conditions for the formation of LaCr /SUB 1-y/ Ni /SUB y/ O 3 , La /SUB 1-x/ Ca /SUB x/ CrO 3 , and La /SUB 1-x/ Ca /SUB x/ Cr /SUB 1-y/ Ni /SUB y/ O 3 solid solutions and the electrical parameters of these. The initial materials were lanthanum, calcium, nickel, and chromium nitrates of pure or analytical grade. It is shown that partial replacement of lanthanum by calcium does not have any substantial effect on the electrical parameters of La /SUB 1-x/ Ca /SUB x/ Cr /SUB 1-y/ Ni /SUB y/ O 3 solid solutions for y = 0.2-0.6, but it increases the conductivity of La /SUB 1-x/ Ca /SUB x/ CrO 3 by three orders of magnitude as x varies from 0 to 0.3. The electrical parameters are virtually the same for lanthanum chromites containing calcium and strontium. The solubility of calcium in lanthanum chromite is reduced in the presence of nickel

Parameter Uncertainty for Repository Thermal Analysis

Energy Technology Data Exchange (ETDEWEB)

Hardin, Ernest [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hadgu, Teklu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Greenberg, Harris [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dupont, Mark [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2015-10-01

This report is one follow-on to a study of reference geologic disposal design concepts (Hardin et al. 2011a). Based on an analysis of maximum temperatures, that study concluded that certain disposal concepts would require extended decay storage prior to emplacement, or the use of small waste packages, or both. The study used nominal values for thermal properties of host geologic media and engineered materials, demonstrating the need for uncertainty analysis to support the conclusions. This report is a first step that identifies the input parameters of the maximum temperature calculation, surveys published data on measured values, uses an analytical approach to determine which parameters are most important, and performs an example sensitivity analysis. Using results from this first step, temperature calculations planned for FY12 can focus on only the important parameters, and can use the uncertainty ranges reported here. The survey of published information on thermal properties of geologic media and engineered materials, is intended to be sufficient for use in generic calculations to evaluate the feasibility of reference disposal concepts. A full compendium of literature data is beyond the scope of this report. The term “uncertainty” is used here to represent both measurement uncertainty and spatial variability, or variability across host geologic units. For the most important parameters (e.g., buffer thermal conductivity) the extent of literature data surveyed samples these different forms of uncertainty and variability. Finally, this report is intended to be one chapter or section of a larger FY12 deliverable summarizing all the work on design concepts and thermal load management for geologic disposal (M3FT-12SN0804032, due 15Aug2012).

Study on EM-parameters and EM-wave absorption properties of materials with bio-flaky particles added

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wenqiang, E-mail: zwqcau@gmail.com [College of Engineering, China Agricultural University, Beijing 100083 (China); Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); Zhang, Deyuan; Xu, Yonggang [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); McNaughton, Ryan [Department of Biomedical Engineering, Boston University, Boston 02215 (United States)

2016-01-01

Bio-flaky particles, fabricated through deposition of carbonyl iron on the surface of disk shaped diatomite, demonstrated beneficial performance on electromagnetic parameters. This paper will detail the improvements to the electromagnetic parameters and absorbing properties of traditional absorbing material generated by the addition of bio-flaky particles. Composites' electromagnetic parameters were measured using the transmission method. Calculated test results confirmed with bio-flaky particles were added, composites' permittivity increased due to the high permeability of bio-flaky particles. Secondly, the permeability of composites increased as a result of the increased volume content of iron particles. Composites with bio-flaky particles added exhibited superlative absorption properties at 0.5 mm thickness, with a maximum reflection loss of approximately −5.1 dB at 14.4 GHz. - Highlights: • Light weight absorbing composites were fabricated with bio-flaky particles added. • SEM results show bio-flaky particles could help the arrangement of FCIPs. • Composites' RL could be improved with bio-flaky particles added. • The RL peak move to lower frequency with bio-flaky particles added.

Study on EM-parameters and EM-wave absorption properties of materials with bio-flaky particles added

International Nuclear Information System (INIS)

Zhang, Wenqiang; Zhang, Deyuan; Xu, Yonggang; McNaughton, Ryan

2016-01-01

Bio-flaky particles, fabricated through deposition of carbonyl iron on the surface of disk shaped diatomite, demonstrated beneficial performance on electromagnetic parameters. This paper will detail the improvements to the electromagnetic parameters and absorbing properties of traditional absorbing material generated by the addition of bio-flaky particles. Composites' electromagnetic parameters were measured using the transmission method. Calculated test results confirmed with bio-flaky particles were added, composites' permittivity increased due to the high permeability of bio-flaky particles. Secondly, the permeability of composites increased as a result of the increased volume content of iron particles. Composites with bio-flaky particles added exhibited superlative absorption properties at 0.5 mm thickness, with a maximum reflection loss of approximately −5.1 dB at 14.4 GHz. - Highlights: • Light weight absorbing composites were fabricated with bio-flaky particles added. • SEM results show bio-flaky particles could help the arrangement of FCIPs. • Composites' RL could be improved with bio-flaky particles added. • The RL peak move to lower frequency with bio-flaky particles added.

Transparent ceramic lamp envelope materials

Energy Technology Data Exchange (ETDEWEB)

Wei, G C [OSRAM SYLVANIA, 71 Cherry Hill Drive, Beverly, MA 01915 (United States)

2005-09-07

Transparent ceramic materials with optical qualities comparable to single crystals of similar compositions have been developed in recent years, as a result of the improved understanding of powder-processing-fabrication- sintering-property inter-relationships. These high-temperature materials with a range of thermal and mechanical properties are candidate envelopes for focused-beam, short-arc lamps containing various fills operating at temperatures higher than quartz. This paper reviews the composition, structure and properties of transparent ceramic lamp envelope materials including sapphire, small-grained polycrystalline alumina, aluminium oxynitride, yttrium aluminate garnet, magnesium aluminate spinel and yttria-lanthana. A satisfactory thermal shock resistance is required for the ceramic tube to withstand the rapid heating and cooling cycles encountered in lamps. Thermophysical properties, along with the geometry, size and thickness of a transparent ceramic tube, are important parameters in the assessment of its resistance to fracture arising from thermal stresses in lamps during service. The corrosive nature of lamp-fill liquid and vapour at high temperatures requires that all lamp components be carefully chosen to meet the target life. The wide range of new transparent ceramics represents flexibility in pushing the limit of envelope materials for improved beamer lamps.

Determination of the exact range of the value of the parameter corresponding to chaos based on the Silnikov criterion

International Nuclear Information System (INIS)

Wei-Yi, Li; Qi-Chang, Zhang; Wei, Wang

2010-01-01

Based on the Silnikov criterion, this paper studies a chaotic system of cubic polynomial ordinary differential equations in three dimensions. Using the Cardano formula, it obtains the exact range of the value of the parameter corresponding to chaos by means of the centre manifold theory and the method of multiple scales combined with Floque theory. By calculating the manifold near the equilibrium point, the series expression of the homoclinic orbit is also obtained. The space trajectory and Lyapunov exponent are investigated via numerical simulation, which shows that there is a route to chaos through period-doubling bifurcation and that chaotic attractors exist in the system. The results obtained here mean that chaos occurred in the exact range given in this paper. Numerical simulations also verify the analytical results. (general)

Cavitational synthesis of nanostructured inorganic materials for enhanced heterogeneous catalysis

Science.gov (United States)

Krausz, Ivo Michael

The synthesis of nanostructured inorganic materials by hydrodynamic cavitation processing was investigated. The goal of this work was to develop a general synthesis technique for nanostructured materials with a control over crystallite size in the 1--20 nm range. Materials with crystallite sizes in this range have shown enhanced catalytic activity compared to materials with larger crystallite sizes. Several supported and unsupported inorganic materials were studied to understand the effects of cavitation on crystallite size. Cavitation processing of calcium fluoride resulted in more spherical particles, attached to one another by melted necks. This work produced the first evidence of shock wave heating of nanostructured materials by hydrodynamic cavitation processing. Hydrodynamic cavitation synthesis of various catalytic support materials indicated that their phase composition and purity could be controlled by adjustment of the processing parameters. Zirconia/alumina supports synthesized using hydro-dynamic cavitation and calcined to 1368 K retained a high purity cubic zirconia phase, whereas classically prepared samples showed a phase transformation to monoclinic zirconia. Similarly, the synthesis of alumina resulted in materials with varying Bohmite and Bayerite contents as a function of the process parameters. High temperature calcination resulted in stable alumina supports with varying amounts of delta-, and theta-alumina. Synthesis studies of palladium and silver showed modest variations in crystallite size as a function of cavitation process parameters. Calcination resulted in larger grain materials, indicating a disappearance of intergrain boundaries. Based on these results, a new synthesis method was studied involving controlled agglomeration of small silver crystallites by hydrodynamic cavitation processing, followed by deposition on alumina. The optimal pH, concentration, and processing time for controlling the silver crystallite size in the cavitation

Savannah River Plant's Accountability Inventory Management System (AIMS) (Nuclear materials inventory control)

International Nuclear Information System (INIS)

Croom, R.G.

1976-06-01

The Accountability Inventory Management System (AIMS) is a new computer inventory control system for nuclear materials at the Savannah River Plant, Aiken, South Carolina. The system has two major components, inventory files and system parameter files. AIMS, part of the overall safeguards program, maintains an up-to-date record of nuclear material by location, produces reports required by ERDA in addition to onplant reports, and is capable of a wide range of response to changing input/output requirements through use of user-prepared parameter cards, as opposed to basic system reprogramming

Study of parameters of heat treatment in obtaining glass ceramic materials with addition of the industrial waste

International Nuclear Information System (INIS)

Kniess, C.T.; Prates, P.B.; Martins, G.J.M.; Riella, H.G.; Matsinhe, Jonas; Kuhnen, N.C.

2012-01-01

The production of materials from crystallization of glass, called glass ceramic, have proved interesting by the possibility of development of different microstructures, with reduced grain size and the presence of residual amorphous phase in different quantities. The method that uses the differential thermal analysis (DTA) provides research on the material properties over a wide temperature range, it's widely applied to crystallization processes of glass ceramic materials. Within this context, this paper aims to study the kinetics of nucleation and crystal growth in glass ceramic materials in the system SiO 2 - Al 2 O 3 -Li 2 O, obtained with the addition of mineral coal bottom ash as source of aluminosilicates, through the technique of differential thermal analysis. (author)

Production, handling and characterization of particulate materials

CERN Document Server

Meesters, Gabriel

2016-01-01

This edited volume presents most techniques and methods that have been developed by material scientists, chemists, chemical engineers and physicists for the commercial production of particulate materials, ranging from the millimeter to the nanometer scale.  The scope includes the physical and chemical background, experimental optimization of equipment and procedures, as well as an outlook on future methods. The books addresses  issues of industrial importance such as specifications, control parameter(s), control strategy, process models, energy consumption and discusses the various techniques in relation to potential applications. In addition to the production processes, all major unit operations and characterization methods are described in this book. It differs from other books which are devoted to a single technique or a single material. Contributors to this book are acknowledged experts in their field. The aim of the book is to facilitate comparison of the different unit operations leading to optimum...

Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters Final Report to the Subsurface Biogeochemical Research Program

Energy Technology Data Exchange (ETDEWEB)

Day-Lewis, Frederick; Singha, Kamini; Haggerty, Roy; Johnson, Timothy; Binley, Andrew; Lane, John

2014-03-10

. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Our study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3-part research plan involving (1) development of computer codes and techniques to estimate mass-transfer parameters from time-lapse electrical data; (2) bench-scale experiments on synthetic materials and materials from cores from the Hanford 300 Area; and (3) field demonstration experiments at the DOE’s Hanford 300 Area.

Solid nanofoams based on cellulose nanofibers and indomethacin-the effect of processing parameters and drug content on material structure

DEFF Research Database (Denmark)

Bannow, J; Benjamins, J-W; Wohlert, J

2017-01-01

to verify the wet-foam stability at different pHs. The pH influenced the amount of solubilized drug and the processing-window was very narrow at high drug loadings. The results were compared to real foaming-experiments and solid state analysis of the final cellular solids. The parameters were assembled...... into a processing chart, highlighting the importance of the right combination of processing parameters (pH and time-point of pH adjustment) in order to successfully prepare cellular solid materials with up to 46 wt% drug loading....

Luminescence model with quantum impact parameter for low energy ions

CERN Document Server

Cruz-Galindo, H S; Martínez-Davalos, A; Belmont-Moreno, E; Galindo, S

2002-01-01

We have modified an analytical model of induced light production by energetic ions interacting in scintillating materials. The original model is based on the distribution of energy deposited by secondary electrons produced along the ion's track. The range of scattered electrons, and thus the energy distribution, depends on a classical impact parameter between the electron and the ion's track. The only adjustable parameter of the model is the quenching density rho sub q. The modification here presented, consists in proposing a quantum impact parameter that leads to a better fit of the model to the experimental data at low incident ion energies. The light output response of CsI(Tl) detectors to low energy ions (<3 MeV/A) is fitted with the modified model and comparison is made to the original model.

Insulating materials for optoelectronics

International Nuclear Information System (INIS)

Agullo-Lopez, F.

1990-01-01

Optoelectronics is an interdisciplinary field. Basic functions of an optoelectronic system include the generator of the optical signal, its transmission and handling and, finally, its detection, storage and display. A large variety of semiconductor and insulating materials are used or are being considered to perform those functions. The authors focus on insulating materials, mostly oxides. For signal generation, tunable solid state lasers, either vibronic or those based oon colour centres are briefly described, and their main operating parameters summarized. Reference is made to some developments on fiber and waveguide lasers. Relevant physical features of the silica fibres used for low-loss, long-band, optical transmission are reviewed, as well as present efforts to further reduce attenuation in the mid-infrared range. Particular attention is paid to photorefractive materials (LiNbO 3 , BGO, BSO, etc.), which are being investigated

Constitutive model for porous materials

International Nuclear Information System (INIS)

Weston, A.M.; Lee, E.L.

1982-01-01

A simple pressure versus porosity compaction model is developed to calculate the response of granular porous bed materials to shock impact. The model provides a scheme for calculating compaction behavior when relatively limited material data are available. While the model was developed to study porous explosives and propellants, it has been applied to a much wider range of materials. The early development of porous material models, such as that of Hermann, required empirical dynamic compaction data. Erkman and Edwards successfully applied the early theory to unreacted porous high explosives using a Gruneisen equation of state without yield behavior and without trapped gas in the pores. Butcher included viscoelastic rate dependance in pore collapse. The theoretical treatment of Carroll and Holt is centered on the collapse of a circular pore and includes radial inertia terms and a complex set of stress, strain and strain rate constitutive parameters. Unfortunately data required for these parameters are generally not available. The model described here is also centered on the collapse of a circular pore, but utilizes a simpler elastic-plastic static equilibrium pore collapse mechanism without strain rate dependence, or radial inertia terms. It does include trapped gas inside the pore, a solid material flow stress that creates both a yield point and a variation in solid material pressure with radius. The solid is described by a Mie-Gruneisen type EOS. Comparisons show that this model will accurately estimate major mechanical features which have been observed in compaction experiments

Description of scattering material behaviour and damage in inelastic materials; Beschreibung von streuendem Materialverhalten und von Schaedigung bei inelastischen Werkstoffen

Energy Technology Data Exchange (ETDEWEB)

Pensky, H.M.H.

2000-07-01

For realistic numerical simulations of the stress-strain behaviour of structures, models are necessary which describe elastic-inelastic and scattering material behaviour. The developed models simulate elastic, viscoplastic and anisotropic damage material phenomena. An approach is proposed for covering stochastic material beahviour by correspondingly distributed parameters of the deterministic material model. Numerical simulations of biaxial material tests and structural tests demonstrate the range of applicability. (orig.) [German] Die realitaetsnahe numerische Simulation des Spannungs-Verformungsverhaltens von Bauteilen erfordert Modelle zur Beschreibung inelastischen und streuenden Materialverhaltens. Die hier entwickelten Modelle beschreiben elastische, viskoplastische und anisotrope Schaedigungsphaenomene des Materialverhaltens. Desweiteren wird ein Konzept vorgestellt, mit dem streuendes Materialverhalten mit streuenden Materialparametersaetzen deterministischer Stoffmodelle beschreibbar ist. Numerische Simulationen von Werkstoff- und Bauteilversuchen veranschaulichen den Anwendungsbereich der Modelle. (orig.)

Finite Element Based Optimization of Material Parameters for Enhanced Ballistic Protection

Science.gov (United States)

Ramezani, Arash; Huber, Daniel; Rothe, Hendrik

2013-06-01

The threat imposed by terrorist attacks is a major hazard for military installations, vehicles and other items. The large amounts of firearms and projectiles that are available, pose serious threats to military forces and even civilian facilities. An important task for international research and development is to avert danger to life and limb. This work will evaluate the effect of modern armor with numerical simulations. It will also provide a brief overview of ballistic tests in order to offer some basic knowledge of the subject, serving as a basis for the comparison of simulation results. The objective of this work is to develop and improve the modern armor used in the security sector. Numerical simulations should replace the expensive ballistic tests and find vulnerabilities of items and structures. By progressively changing the material parameters, the armor is to be optimized. Using a sensitivity analysis, information regarding decisive variables is yielded and vulnerabilities are easily found and eliminated afterwards. To facilitate the simulation, advanced numerical techniques have been employed in the analyses.

Hugoniot elastic limits and compression parameters for brittle materials

International Nuclear Information System (INIS)

Gust, W.H.

1979-01-01

The physical properties of brittle materials are of interest because of the rapidly expanding use of these material in high-pressure and shock wave techology, e.g., geophysics and explosive compaction as well as military applications. These materials are characterized by unusually high sonic velocities, have large dynamic impedances and exhibit large dynamic yield strengths

Displacement cascades in diatomic materials

International Nuclear Information System (INIS)

Parkin, D.M.; Coulter, C.A.

1981-01-01

A new function, the specified-projectile displacement function p/sub ijk/ (E), is introduced to describe displacement cascades in polyatomic materials. This function describes the specific collision events that produce displacements and hence adds new information not previously available. Calculations of p/sub ijk/ (E) for MgO, Al 2 O 3 and TaO are presented and discussed. Results show that the parameters that have the largest effect on displacement collision events are the PKA energy and the mass ratio of the atom types in the material. It is further shown that the microscopic nature of the displacement events changes over the entire recoil energy range relevant to fusion neutron spectra and that these changes are different in materials whose mass ratio is near one than in those where it is far from one

Mathematical modeling of a biogenous filter cake and identification of oilseed material parameters

Directory of Open Access Journals (Sweden)

Očenášek J.

2009-12-01

Full Text Available Mathematical modeling of the filtration and extrusion process inside a linear compression chamber has gained a lot of attention during several past decades. This subject was originally related to mechanical and hydraulic properties of soils (in particular work of Terzaghi and later was this approach adopted for the modeling of various technological processes in the chemical industry (work of Shirato. Developed mathematical models of continuum mechanics of porous materials with interstitial fluid were then applied also to the problem of an oilseed expression. In this case, various simplifications and partial linearizations are introduced in models for the reason of an analytical or numerical solubility; or it is not possible to generalize the model formulation into the fully 3D problem of an oil expression extrusion with a complex geometry such as it has a screw press extruder.We proposed a modified model for the oil seeds expression process in a linear compression chamber. The model accounts for the rheological properties of the deformable solid matrix of compressed seed, where the permeability of the porous solid is described by the Darcy's law. A methodology of the experimental work necessary for a material parameters identification is presented together with numerical simulation examples.

Constitutive modelling in the range of inelastic deformations

International Nuclear Information System (INIS)

Bruhns, O.T.; White, P.S.; Chaboche, J.L.; Eikhoff, J.V.D.

1988-01-01

The main objective of this report is to describe the state of the art in constitutive modelling in the range of inelastic deformations, with particular consideration of the practical use of these models in the field of fast reactors, rather than to formulate new models. An outline is given of the constitutive equations for high-temperature reactor materials developed at the Oak Ridge National Laboratory. Two forms of equations are considered, a semi-classical treatment in terms of separate plasticity and creep and unified equations in which the classical plasticity does not explicitly occur. The fraction model originally proposed by Besseling is described. The basic concept of this model is that the material is thought to be subdivided into a number of parallel fractions, each with simple conventional properties. The more complicated behaviour of real material is thus approximated by choosing a number of parallel fractions with suitable models and model parameters. Three time-independent formulations of plasticity are considered and compared. Attention is focused on the kinematic hardening in the multi-yield surface theory of Mroz and the non-linear kinematic rule intensively used at Enset and Onera. Some connections are pointed out with the two-surface model of Dafalias and Popov, and the range of applicability of the different models is studied in detail. Finally, the constitutive equations of the Interatom model are presented. They are mainly based on the concept of overstresses, expressing the rate-dependence of the material by the magnitude of these overstresses. This model furthermore comprises a combination of general non-linear isotropic and kinematic hardening, with a smooth transition from isotropic to kinematic hardening as a function of process time

Application of benchtop micro-XRF to geological materials

DEFF Research Database (Denmark)

Flude, Stephanie; Haschke, Michael; Storey, Michael

2017-01-01

Recent developments in X-ray optics have allowed the development of a range of commercially available benchtop micro-XRF (μ-XRF) instruments that can produce X-ray spot sizes of 20–30 μm on the sample, allowing major- and trace-element analysis on a range of sample types and sizes with minimal......, by using a simple type-calibration against a reference material of similar matrix and composition. Qualitative analysis with micro-XRF can simplify and streamline sample characterization and processing for subsequent geochemical and isotopic analysis....... sample preparation. Such instruments offer quantitative analysis using fundamental parameter based 'standardless' quantification algorithms. The accuracy and precision of this quantitative analysis on geological materials, and application of micro-XRF to wider geological problems is assessed using...

Experimental Research on The Deformability of a Geological Material: Initial Characterisation and Identification of Parameters

International Nuclear Information System (INIS)

Villar, M.V.; Udias, A.; Canamon, I.; Robles, J.

2006-01-01

This document reflects the work performed at CIEMAT (Engineered and Geological Barriers Group) in the framework of the RTD Project BTE2002-04244-C02-02 (DEF-NOSAT). The first phase of the project consisted on the selection and characterisation of a geological material fitted for unsaturated triaxial testing. The result obtained during this phase gave place to the selection of a silty clay from Alcala de Henares (Madrid, Spain). Compaction and permeability tests were performed as well as studies on mixtures of this soil with sand. With the selected mixtures (70/30 and 50/50 percent sand/soil) isotropic compression tests were carried out in the saturated sample. The results of these tests have allowed the determination of some of the parameters needed to model the mechanical behaviour of the soil. The report includes also a brief description of a methodology developed in the Department of Applied Mathematics and Computer Methods of the Universidad Politecnica de Madrid for getting these parameters by optimisation of the experimental results, as well as the results obtained. (Author) 25 refs

Dimensional ranges and rolling efficiency in a tandem cold rolling mill

Energy Technology Data Exchange (ETDEWEB)

Larkiola, J.

1997-12-31

In this work, physical models and a neural network theory have been combined in order to predict the properties of a steel strip and to optimise the process parameters in cold rolling. The prediction of the deformation resistance of the material and the friction parameter is based on the physical model presented by Bland, Ford and Ellis and artificial neural network computing (ANN). The accuracy of these models has been tested and proved by using a large amount of the measured data. With the aid of these models it has been shown that (a) the small change to the relative reduction distribution can have a clear effect upon the rolling efficiency, (b) the dimensional ranges of the tandem cold roll mill can be determined and optimised and (c) the possibility to cold roll a new product of new width, strength or thickness can be determined and the parameters of the tandem cold rolling process can be optimised. (orig.) 43 refs.

A new Material Practice

DEFF Research Database (Denmark)

Tamke, Martin; Lafuente Hernández, Elisa; Deleuran, Anders

2012-01-01

Advances in computational techniques allow for the integration of simulation in the initial design phase of architecture. This approach extends the range of the architectural intent to performative aspects of the overall structure and its elements. However, this also changes the process of design...... from the primacy of geometrical concerns to the negotiation between encoded parameters. Material behavior was the focus of the research project that led to the Dermoid 1:1 demonstrator build in Copenhagen. Dermoid was a 1:1 prototype, plywood structure that explored how the induced flex of plywood...

Resistance Upset Welding of ODS Steel Fuel Claddings—Evaluation of a Process Parameter Range Based on Metallurgical Observations

Directory of Open Access Journals (Sweden)

Fabien Corpace

2017-08-01

Full Text Available Resistance upset welding is successfully applied to Oxide Dispersion Strengthened (ODS steel fuel cladding. Due to the strong correlation between the mechanical properties and the microstructure of the ODS steel, this study focuses on the consequences of the welding process on the metallurgical state of the PM2000 ODS steel. A range of process parameters is identified to achieve operative welding. Characterizations of the microstructure are correlated to measurements recorded during the welding process. The thinness of the clad is responsible for a thermal unbalance, leading to a higher temperature reached. Its deformation is important and may lead to a lack of joining between the faying surfaces located on the outer part of the join which can be avoided by increasing the dissipated energy or by limiting the clad stick-out. The deformation and the temperature reached trigger a recrystallization phenomenon in the welded area, usually combined with a modification of the yttrium dispersion, i.e., oxide dispersion, which can damage the long-life resistance of the fuel cladding. The process parameters are optimized to limit the deformation of the clad, preventing the compactness defect and the modification of the nanoscale oxide dispersion.

On the coordination chemistry of humic materials

International Nuclear Information System (INIS)

Grauer, R.

1989-01-01

Dissolved humic materials form ligands which can influence the speciation of certain radionuclides in natural waters and it is necessary to take account of this phenomenon in repository safety assessment model calculations. There are no models available which give a basic description of the wide range of complexation properties of humic materials with dissolved metals and which are based on a chemically meaningful background. All of these models make very drastic simplifications and, although capable of reproducing experimental data, they do not allow any extrapolation to ranges of concentration outside those covered by the experiments. Humic materials affect not only the solution chemistry of the metals but also their sorption onto minerals. The mineral surfaces are modified through adsorption of organic material which in turn alters their sorption properties. These processes are understood in qualitative terms. It is unlikely that a comprehensive predictive model of complexation by humic materials will be available in the foreseeable future. It is therefore suggested that experiments which provide an empirical description of the metal/humic material interaction using realistic pH values and metal/ligand ratios be carried out. Besides parameter studies and experiments in synthetic or formation waters, analogue studies could also serve as a useful tool. 132 refs., 51 figs., 12 tabs

Simultaneous estimation of experimental and material parameters

CSIR Research Space (South Africa)

Jansen van Rensburg, GJ

2012-07-01

Full Text Available to the experimental data. An inverse analysis is performed that determines material properties and boundary conditions simultaneously. This idea is investigated using virtual experimental data. The virtual experimental data is obtained by performing a finite element...

Health assessment of free-ranging endangered Australian sea lion (Neophoca cinerea) pups: effect of haematophagous parasites on haematological parameters.

Science.gov (United States)

Marcus, Alan D; Higgins, Damien P; Gray, Rachael

2015-06-01

Evaluation of the health status of free-ranging populations is important for understanding the impact of disease on individuals and on population demography and viability. In this study, haematological reference intervals were developed for free-ranging endangered Australian sea lion (Neophoca cinerea) pups within the context of endemic hookworm (Uncinaria sanguinis) infection and the effects of pathogen, host, and environment factors on the variability of haematological parameters were investigated. Uncinaria sanguinis was identified as an important agent of disease, with infection causing regenerative anaemia, hypoproteinaemia, and a predominantly lymphocytic-eosinophilic systemic inflammatory response. Conversely, the effects of sucking lice (Antarctophthirus microchir) were less apparent and infestation in pups appears unlikely to cause clinical impact. Overall, the effects of U. sanguinis, A. microchir, host factors (standard length, body condition, pup sex, moult status, and presence of lesions), and environment factors (capture-type and year of sampling) accounted for 26-65% of the total variance observed in haematological parameters. Importantly, this study demonstrated that anaemia in neonatal Australian sea lion pups is not solely a benign physiological response to host-environment changes, but largely reflects a significant pathological process. This impact of hookworm infection on pup health has potential implications for the development of foraging and diving behaviour, which would subsequently influence the independent survival of juveniles following weaning. The haematological reference intervals developed in this study can facilitate long-term health surveillance, which is critical for the early recognition of changes in disease impact and to inform conservation management. Copyright © 2015 Elsevier Inc. All rights reserved.

Experimental study on stabilizing range extension of diamagnetic levitation under modulated magnetic field

Energy Technology Data Exchange (ETDEWEB)

Chow, T C S; Wong, P L; Liu, K P, E-mail: 50578230@student.cityu.edu.h, E-mail: meplwong@cityu.edu.h, E-mail: mekpliu@cityu.edu.h [Manufacturing Engineering and Engineering Management Department, City University of Hong Kong, Tat Chee Avenue, Kowloon (Hong Kong)

2010-01-01

The real energy-free levitation exists with the help of diamagnetic material. Its ultra-high sensitivity to force is particularly attractive to micro/nano force sensing. A key parameter: Levitation Stabilizing Local Range, LR (allowable moving range of the floater) is critical to the load and self-rotating performance. Besides, larger LR reduces the energy loss due to the eddy current and has greater application potential. Recently, an idea of extending the LR by a modulating coil array has been validated using numerical simulation. This paper takes the next move to carry out an experimental study on the shape effect of stacked coil arrays with different currents on LR.

Effect of material parameters on stress wave propagation during fast upsetting

Institute of Scientific and Technical Information of China (English)

WANG Zhong-jin; CHENG Li-dong

2008-01-01

Based'on a dynamic analysis method and an explicit algorithm, a dynamic explicit finite element code was developed for modeling the fast upsetting process of block under drop hammer impact, in which the hammer velocity during the deformation was calculated by energy conservation law according to the operating principle of hammer equipment. The stress wave propagation and its effect on the deformation were analyzed by the stress and strain distributions. Industrial pure lead, oxygen-free high-conductivity (OFHC) copper and 7039 aluminum alloy were chosen to investigate the effect of material parameters on the stress wave propagation. The results show that the stress wave propagates from top to bottom of block, and then reflects back when it reaches the bottom surface. After that, stress wave propagates and reflects repeatedly between the upper surface and bottom surface. The stress wave propagation has a significant effect on the deformation at the initial stage, and then becomes weak at the middle-final stage. When the ratio of elastic modulus or the slope of stress-strain curve to mass density becomes larger, the velocity of stress wave propagation increases, and the influence of stress wave on the deformation becomes small.

Determination of parameters used to prevent ignition of stored materials and to protect against explosions in food industries.

Science.gov (United States)

Ramírez, Alvaro; García-Torrent, Javier; Aguado, Pedro J

2009-08-30

There are always risks associated with silos when the stored material has been characterized as prone to self-ignition or explosion. Further research focused on the characterization of agricultural materials stored in silos is needed due to the lack of data found in the literature. The aim of this study was to determine the ignitability and explosive parameters of several agricultural products commonly stored in silos in order to assess the risk of ignition and dust explosion. Minimum Ignition Temperature, with dust forming a cloud and deposited in a layer, Lower Explosive Limit, Minimum Ignition Energy, Maximum Explosion Pressure and Maximum Explosion Pressure Rise were determined for seven agricultural materials: icing sugar, maize, wheat and barley grain dust, alfalfa, bread-making wheat and soybean dust. Following characterization, these were found to be prone to producing self-ignition when stored in silos under certain conditions.

Comparison of physically based constitutive models characterizing armor steel over wide temperature and strain rate ranges

International Nuclear Information System (INIS)

Xu, Zejian; Huang, Fenglei

2012-01-01

Both descriptive and predictive capabilities of five physically based constitutive models (PB, NNL, ZA, VA, and RK) are investigated and compared systematically, in characterizing plastic behavior of the 603 steel at temperatures ranging from 288 to 873 K, and strain rates ranging from 0.001 to 4500 s −1 . Determination of the constitutive parameters is introduced in detail for each model. Validities of the established models are checked by strain rate jump tests performed under different loading conditions. The results show that the RK and NNL models have better performance in the description of material behavior, especially the work-hardening effect, while the PB and VA models predict better. The inconsistency that is observed between the capabilities of description and prediction of the models indicates the existence of the minimum number of required fitting data, reflecting the degree of a model's requirement for basic data in parameter calibration. It is also found that the description capability of a model is dependent to a large extent on both its form and the number of its constitutive parameters, while the precision of prediction relies largely on the performance of description. In the selection of constitutive models, the experimental data and the constitutive models should be considered synthetically to obtain a better efficiency in material behavior characterization

A comparative study on optimization of machining parameters by turning aerospace materials according to Taguchi method

Directory of Open Access Journals (Sweden)

Altin Abdullah

2017-01-01

Full Text Available The effects of cutting tool coating material and cutting speed on cutting forces and surface roughness were investigated by Taguchi experimental design. Main cutting force, Fz is considered as a criterion. The effects of machining parameters were investigated using Taguchi L18 orthogonal array. Optimal cutting conditions were determined using the signal-to-noise (S/N ratio which is calculated for average surface roughness and cutting force according to the “the smaller is better” approach. Using results of analysis of variance (ANOVA and signal-to-noise (S/N ratio, effects of parameters on both average surface roughness and cutting forces were statistically investigated. It was observed that feed rate and cutting speed had higher effect on cutting force in Hastelloy X, while the feed rate and cutting tool had higher effect on cutting force in Inconel 625. According to average surface roughness the cutting tool and feed rate had higher effect in Hastelloy X and Inconel 625.

Gamma rays shielding parameters for white metal alloys

Science.gov (United States)

Kaur, Taranjot; Sharma, Jeewan; Singh, Tejbir

2018-05-01

In the present study, an attempt has been made to check the feasibility of white metal alloys as gamma rays shielding materials. Different combinations of cadmium, lead, tin and zinc were used to prepare quaternary alloys Pb60Sn20ZnxCd20-x (where x = 5, 10, 15) using melt quench technique. These alloys were also known as white metal alloys because of its shining appearance. The density of prepared alloys has been measured using Archimedes Principle. Gamma rays shielding parameters viz. mass attenuation coefficient (µm), effective atomic number (Zeff), electron density (Nel), Mean free path (mfp), Half value layer (HVL) and Tenth value layer (TVL) has been evaluated for these alloys in the wide energy range from 1 keV to 100 GeV. The WinXCom software has been used for obtaining mass attenuation coefficient values for the prepared alloys in the given energy range. The effective atomic number (Zeff) has been assigned to prepared alloys using atomic to electronic cross section ratio method. Further, the variation of various shielding parameters with photon energy has been investigated for the prepared white metal alloys.

The Virtual Fields Method Extracting Constitutive Mechanical Parameters from Full-field Deformation Measurements

CERN Document Server

Pierron, Fabrice

2012-01-01

The Virtual Fields Method: Extracting Constitutive Mechanical Parameters from Full-field Deformation Measurements is the first book on the Virtual Fields Method (VFM), a technique to identify materials mechanical properties from full-field measurements. Firmly rooted with extensive theoretical description of the method, the book presents numerous examples of application to a wide range of materials (composites, metals, welds, biomaterials) and situations (static, vibration, high strain rate). The authors give a detailed training section with examples of progressive difficulty to lead the reader to program the VFM and include a set of commented Matlab programs as well as GUI Matlab-based software for more general situations. The Virtual Fields Method: Extracting Constitutive Mechanical Parameters from Full-field Deformation Measurements is an ideal book for researchers, engineers, and students interested in applying the VFM to new situations motivated by their research.  

A proposal for evaluation method of crack growth due to cyclic overload for piping materials based on an elastic-plastic fracture mechanics parameter

International Nuclear Information System (INIS)

Yamaguchi, Yoshihito; Katsuyama, Jinya; Onizawa, Kunio; Li, Yinsheng; Sugino, Hideharu

2011-01-01

The magnitude of Niigata-ken Chuetsu-Oki earthquake in 2007 was beyond the assumed one provided in seismic design. Therefore it becomes an important issue to evaluate the crack growth behaviors due to the cyclic overload like large earthquake. Fatigue crack growth is usually evaluated by Paris's law using the range of stress intensity factor (ΔK). However, ΔK is inappropriate in a loading condition beyond small scale yielding. In this study, the crack growth behaviors for piping materials were investigated based on an elastic-plastic fracture mechanics parameter, J-integral. It was indicated that the crack growth due to the cyclic overload beyond small scale yielding could be the sum of fatigue and ductile crack growth. The retardation effect of excessive loading on the crack growth was observed after the loading. The modified Wheeler model using J-integral has been proposed for the prediction of retardation effect. Finally, an evaluation method for crack growth behaviors due to the cyclic overload is suggested. (author)

Process Damping Parameters

International Nuclear Information System (INIS)

Turner, Sam

2011-01-01

The phenomenon of process damping as a stabilising effect in milling has been encountered by machinists since milling and turning began. It is of great importance when milling aerospace alloys where maximum surface speed is limited by excessive tool wear and high speed stability lobes cannot be attained. Much of the established research into regenerative chatter and chatter avoidance has focussed on stability lobe theory with different analytical and time domain models developed to expand on the theory first developed by Trusty and Tobias. Process damping is a stabilising effect that occurs when the surface speed is low relative to the dominant natural frequency of the system and has been less successfully modelled and understood. Process damping is believed to be influenced by the interference of the relief face of the cutting tool with the waveform traced on the cut surface, with material properties and the relief geometry of the tool believed to be key factors governing performance. This study combines experimental trials with Finite Element (FE) simulation in an attempt to identify and understand the key factors influencing process damping performance in titanium milling. Rake angle, relief angle and chip thickness are the variables considered experimentally with the FE study looking at average radial and tangential forces and surface compressive stress. For the experimental study a technique is developed to identify the critical process damping wavelength as a means of measuring process damping performance. For the range of parameters studied, chip thickness is found to be the dominant factor with maximum stable parameters increased by a factor of 17 in the best case. Within the range studied, relief angle was found to have a lesser effect than expected whilst rake angle had an influence.

Material parameter identification on metal matrix composites

CSIR Research Space (South Africa)

Jansen van Rensburg, GJ

2012-07-01

Full Text Available conditions that best replicate the experimental data. The quality of the fits is subject to the limits of the material model and boundary parameterisation. An alternative procedure that uses the time and strain history to evolve the yield stress is also...

Short-range fundamental forces

International Nuclear Information System (INIS)

Antoniadis, I.; Baessler, S.; Buchner, M.; Fedorov, V.V.; Hoedl, S.; Nesvizhevsky, V.V.; Pignol, G.; Protasov, K.V.; Lambrecht, A.; Reynaud, S.; Sobolev, Y.

2010-01-01

We consider theoretical motivations to search for extra short-range fundamental forces as well as experiments constraining their parameters. The forces could be of two types: 1) spin-independent forces; 2) spin-dependent axion-like forces. Different experimental techniques are sensitive in respective ranges of characteristic distances. The techniques include measurements of gravity at short distances, searches for extra interactions on top of the Casimir force, precision atomic and neutron experiments. We focus on neutron constraints, thus the range of characteristic distances considered here corresponds to the range accessible for neutron experiments

Theoretical Determination of Optimal Material Parameters for ZnCdTe/ZnCdSe Quantum Dot Intermediate Band Solar Cells

Science.gov (United States)

Imperato, C. M.; Ranepura, G. A.; Deych, L. I.; Kuskovsky, I. L.

2018-03-01

Intermediate band solar cells (IBSCs) are designed to enhance the photovoltaic efficiency significantly over that of a single-junction solar cell as determined by the Shockley-Queisser limit. In this work we present calculations to determine parameters of type-II Zn1-xCdxTe/Zn1-yCdySe quantum dots (QDs) grown on the InP substrate suitable for IBSCs. The calculations are done via the self-consistent variational method, accounting for the disk form of the QDs, presence of the strained ZnSe interfacial layer, and under conditions of a strain-free device structure. We show that to achieve the required parameters relatively thick QDs are required. Barriers must contain Cd concentration in the range of 35-44%, while Cd concentration in QD can vary widely from 0% to 70%, depending on their thickness to achieve the intermediate band energies in the range of 0.50-0.73 eV. It is also shown that the results are weakly dependent on the barrier thickness.

Comprehensive reference ranges for hematology and clinical chemistry laboratory parameters derived from normal Nigerian adults.

Directory of Open Access Journals (Sweden)

Timzing Miri-Dashe

Full Text Available Interpretation of laboratory test results with appropriate diagnostic accuracy requires reference or cutoff values. This study is a comprehensive determination of reference values for hematology and clinical chemistry in apparently healthy voluntary non-remunerated blood donors and pregnant women.Consented clients were clinically screened and counseled before testing for HIV, Hepatitis B, Hepatitis C and Syphilis. Standard national blood donors' questionnaire was administered to consented blood donors. Blood from qualified volunteers was used for measurement of complete hematology and chemistry parameters. Blood samples were analyzed from a total of 383 participants, 124 (32.4% males, 125 (32.6% non-pregnant females and 134 pregnant females (35.2% with a mean age of 31 years. Our results showed that the red blood cells count (RBC, Hemoglobin (HB and Hematocrit (HCT had significant gender difference (p = 0.000 but not for total white blood count (p>0.05 which was only significantly higher in pregnant verses non-pregnant women (p = 0.000. Hemoglobin and Hematocrit values were lower in pregnancy (P = 0.000. Platelets were significantly higher in females than men (p = 0.001 but lower in pregnant women (p =  .001 with marked difference in gestational period. For clinical chemistry parameters, there was no significant difference for sodium, potassium and chloride (p>0.05 but gender difference exists for Bicarbonate (HCO3, Urea nitrogen, Creatinine as well as the lipids (p0.05.Hematological and Clinical Chemistry reference ranges established in this study showed significant gender differences. Pregnant women also differed from non-pregnant females and during pregnancy. This is the first of such comprehensive study to establish reference values among adult Nigerians and difference observed underscore the need to establish reference values for different populations.

Calculation of electromagnetic parameter based on interpolation algorithm

International Nuclear Information System (INIS)

Zhang, Wenqiang; Yuan, Liming; Zhang, Deyuan

2015-01-01

Wave-absorbing material is an important functional material of electromagnetic protection. The wave-absorbing characteristics depend on the electromagnetic parameter of mixed media. In order to accurately predict the electromagnetic parameter of mixed media and facilitate the design of wave-absorbing material, based on the electromagnetic parameters of spherical and flaky carbonyl iron mixture of paraffin base, this paper studied two different interpolation methods: Lagrange interpolation and Hermite interpolation of electromagnetic parameters. The results showed that Hermite interpolation is more accurate than the Lagrange interpolation, and the reflectance calculated with the electromagnetic parameter obtained by interpolation is consistent with that obtained through experiment on the whole. - Highlights: • We use interpolation algorithm on calculation of EM-parameter with limited samples. • Interpolation method can predict EM-parameter well with different particles added. • Hermite interpolation is more accurate than Lagrange interpolation. • Calculating RL based on interpolation is consistent with calculating RL from experiment

SU-G-TeP1-02: Analytical Stopping Power and Range Parameterization for Therapeutic Energy Intervals

Energy Technology Data Exchange (ETDEWEB)

Donahue, W [Louisiana State University, Baton Rouge, LA (United States); Newhauser, W [Louisiana State University, Baton Rouge, LA (United States); Mary Bird Perkins Cancer Center, Baton Rouge, LA (United States); Ziegler, J F [United States Naval Academy, Annapolis, MD (United States)

2016-06-15

Purpose: To develop a simple, analytic parameterization of stopping power and range, which covers a wide energy interval and is applicable to many species of projectile ions and target materials, with less than 15% disagreement in linear stopping power and 1 mm in range. Methods: The new parameterization was required to be analytically integrable from stopping power to range, and continuous across the range interval of 1 µm to 50 cm. The model parameters were determined from stopping power and range data for hydrogen, carbon, iron, and uranium ions incident on water, carbon, aluminum, lead and copper. Stopping power and range data was taken from SRIM. A stochastic minimization algorithm was used to find model parameters, with 10 data points per energy decade. Additionally, fitting was performed with 2 and 26 data points per energy decade to test the model’s robustness to sparse Results: 6 free parameters were sufficient to cover the therapeutic energy range for each projectile ion species (e.g. 1 keV – 300 MeV for protons). The model agrees with stopping power and range data well, with less than 9% relative stopping power difference and 0.5 mm difference in range. As few as, 4 bins per decade were required to achieve comparable fitting results to the full data set. Conclusion: This study successfully demonstrated that a simple analytic function can be used to fit the entire energy interval of therapeutic ion beams of hydrogen and heavier elements. Advantages of this model were the small number (6) of free parameters, and that the model calculates both stopping power and range. Applications of this model include GPU-based dose calculation algorithms and Monte Carlo simulations, where available memory is limited. This work was supported in part by a research agreement between United States Naval Academy and Louisiana State University: Contract No N00189-13-P-0786. In addition, this work was accepted for presentation at the American Nuclear Society Annual Meeting

SU-G-TeP1-02: Analytical Stopping Power and Range Parameterization for Therapeutic Energy Intervals

International Nuclear Information System (INIS)

Donahue, W; Newhauser, W; Ziegler, J F

2016-01-01

Purpose: To develop a simple, analytic parameterization of stopping power and range, which covers a wide energy interval and is applicable to many species of projectile ions and target materials, with less than 15% disagreement in linear stopping power and 1 mm in range. Methods: The new parameterization was required to be analytically integrable from stopping power to range, and continuous across the range interval of 1 µm to 50 cm. The model parameters were determined from stopping power and range data for hydrogen, carbon, iron, and uranium ions incident on water, carbon, aluminum, lead and copper. Stopping power and range data was taken from SRIM. A stochastic minimization algorithm was used to find model parameters, with 10 data points per energy decade. Additionally, fitting was performed with 2 and 26 data points per energy decade to test the model’s robustness to sparse Results: 6 free parameters were sufficient to cover the therapeutic energy range for each projectile ion species (e.g. 1 keV – 300 MeV for protons). The model agrees with stopping power and range data well, with less than 9% relative stopping power difference and 0.5 mm difference in range. As few as, 4 bins per decade were required to achieve comparable fitting results to the full data set. Conclusion: This study successfully demonstrated that a simple analytic function can be used to fit the entire energy interval of therapeutic ion beams of hydrogen and heavier elements. Advantages of this model were the small number (6) of free parameters, and that the model calculates both stopping power and range. Applications of this model include GPU-based dose calculation algorithms and Monte Carlo simulations, where available memory is limited. This work was supported in part by a research agreement between United States Naval Academy and Louisiana State University: Contract No N00189-13-P-0786. In addition, this work was accepted for presentation at the American Nuclear Society Annual Meeting

Simulation of sound transmission through the porous material, determining the parameters of acoustic absorption and sound reduction

Directory of Open Access Journals (Sweden)

Zvolenský Peter

2018-01-01

Full Text Available Currently, the quality of structural design of a railway coach is evaluated by so called acoustic comfort, which is characterized by achieved levels of internal noise. Therefore, acoustic parameters of car body are being developed purposely. The paper presents the results of the computer simulation of noise transmission through the wagon walls and the use of noise tests from the train running. The acoustic properties of the original and new materials in the care body are compared.

Modeling the effects of electrical and non-electrical parameters on the material removal and surface integrity in case of µEDM of a non-conductive ceramic material using a combined fuzzy-AOM approach

DEFF Research Database (Denmark)

Puthumana, Govindan

2016-01-01

Micro-EDM is a non-contact process based on the thermoelectric energy between a tool electrode and a workpiece. In μEDM process, the mechanism of material removal is melting and evaporation. The thermal energy in the discharge plasma helps remove material from the workpiece, at the same time...... and surface integrity for a non-conductive ceramic material. The fuzzy logic modeling system is employed for predicting the μEDM process responses. The trends in the material removal rate and hardness values with the chosen electrical and non-electrical parameter for the model and obtained using AOM approach...... are compared. The average deviation between the model predictions and the results obtained using AOM plots is less than 10%. The material removal rate (MRR) decreases linearly with voltage, indicating a difference in material removal mechanism in the μEDM of non-conductive materials....

Thermal conductivity of an organic phase change material/expanded graphite composite across the phase change temperature range and a novel thermal conductivity model

International Nuclear Information System (INIS)

Ling, Ziye; Chen, Jiajie; Xu, Tao; Fang, Xiaoming; Gao, Xuenong; Zhang, Zhengguo

2015-01-01

Highlights: • Expanded graphite can improve thermal conductivity of RT44HC by 20–60 times. • Thermal conductivity of PCM/EG composites keeps constant before/after melting. • Thermal conductivity of PCMs nearly doubled during phase changing. • Thermal conductivity of composite PCM increases with density and percentage of EG. • The simple model predicts thermal conductivity of EG-based composites accurately. - Abstract: This work studies factors that affect the thermal conductivity of an organic phase change material (PCM), RT44HC/expanded graphite (EG) composite, which include: EG mass fraction, composite PCM density and temperature. The increase of EG mass fraction and bulk density will both enhance thermal conductivity of composite PCMs, by up to 60 times. Thermal conductivity of RT44HC/EG composites remains independent on temperature outside the phase change range (40–45 °C), but nearly doubles during the phase change. The narrow temperature change during the phase change allows the maximum heat flux or minimum temperature for heat source if attaching PCMs to a first (constant temperature) or second (constant heat flux) thermal boundary. At last, a simple thermal conductivity model for EG-based composites is put forward, based on only two parameters: mass fraction of EG and bulk density of the composite. This model is validated with experiment data presented in this paper and in literature, showing this model has general applicability to any composite of EG and poor thermal conductive materials

The calculation of some gamma shielding parameters for semiconductor CsPbBr3

Science.gov (United States)

Oto, Berna; Gulebaglan, Sinem Erden; Kanberoglu, Gulsah Saydan

2017-02-01

Recently, researchers produced perovskites structures used in optoelectronic devices as substrates, sensors. CsPbBr3 crystal is found in the cubic perovskite structure and its space group is Pm-3m. CsPbBr3 is a developing material for detection of X- and γ-ray radiations and the knowledge of the attenuation parameters of CsPbBr3 crystal is important. In this study, some photon shielding parameters such as mass attenuation coefficient (μρ), effective atomic number (Zeff) and electron density (Nel) have been investigated for CsPbBr3 compound. The theoretical values of μρ have been calculated in the energy range from 1 keV to 100 GeV using WinXCom computer code and these values have been used in order to calculate the values of Zeff and Nel in the same energy range.

Numerical study of the influence of material parameters on the mechanical behaviour of a rehabilitated edentulous mandible.

Science.gov (United States)

Favot, Louis-Marc; Berry-Kromer, Valérie; Haboussi, Mohamed; Thiebaud, Frédéric; Ben Zineb, Tarak

2014-03-01

The study dealt with full dental prosthetic reconstruction on four implants. The aim was to analyse the influence of material parameters on the mechanical behaviour of the restored mandible compared to the natural mandible. A finite element model of an edentulous mandible with prosthetic rehabilitation was established. Four materials were investigated for the framework of the prosthesis (zirconia, titanium, gold and nickel-titanium (NiTi)), as well as three cortical bone thicknesses. Various muscles were employed to simulate the main stages of mastication. Three distinct phases of mastication were modelled: maximum intercuspation, incisal clench and unilateral molar clench. The zirconia framework demonstrated the highest stresses and NiTi the weakest. The highest stresses in the framework were obtained during maximum intercuspation. The highest stresses at the bone-implant interface were recorded on the working axial implant during unilateral molar clench and on tilted implants during maximum intercuspation. The influence of the framework's material stiffness on the stresses at the bone-implant interface was insignificant for axial implants (except the right implant during unilateral molar clench) and slightly more significant for tilted implants. Mandibular flexion decreased with an increase of the cortical bone thickness and the stiffness of the prosthetic framework's material. Among all materials, NiTi allowed a better preservation of the mandibular flexure, during all the mastication stages. Compared to stiffer materials, NiTi also permitted physiological mechanical conditions at the bone/implant interface, in almost all mastication stages. Copyright © 2013 Elsevier Ltd. All rights reserved.

Laser Processing of Multilayered Thermal Spray Coatings: Optimal Processing Parameters

Science.gov (United States)

Tewolde, Mahder; Zhang, Tao; Lee, Hwasoo; Sampath, Sanjay; Hwang, David; Longtin, Jon

2017-12-01

Laser processing offers an innovative approach for the fabrication and transformation of a wide range of materials. As a rapid, non-contact, and precision material removal technology, lasers are natural tools to process thermal spray coatings. Recently, a thermoelectric generator (TEG) was fabricated using thermal spray and laser processing. The TEG device represents a multilayer, multimaterial functional thermal spray structure, with laser processing serving an essential role in its fabrication. Several unique challenges are presented when processing such multilayer coatings, and the focus of this work is on the selection of laser processing parameters for optimal feature quality and device performance. A parametric study is carried out using three short-pulse lasers, where laser power, repetition rate and processing speed are varied to determine the laser parameters that result in high-quality features. The resulting laser patterns are characterized using optical and scanning electron microscopy, energy-dispersive x-ray spectroscopy, and electrical isolation tests between patterned regions. The underlying laser interaction and material removal mechanisms that affect the feature quality are discussed. Feature quality was found to improve both by using a multiscanning approach and an optional assist gas of air or nitrogen. Electrically isolated regions were also patterned in a cylindrical test specimen.

A combined experimental and analytical approach for interface fracture parameters of dissimilar materials in electronic packages

International Nuclear Information System (INIS)

Kay, N.R.; Ghosh, S.; Guven, I.; Madenci, E.

2006-01-01

This study concerns the development of a combined experimental and analytical technique to determine the critical values of fracture parameters for interfaces between dissimilar materials in electronic packages. This technique utilizes specimens from post-production electronic packages. The mechanical testing is performed inside a scanning electron microscope while the measurements are achieved by means of digital image correlation. The measured displacements around the crack tip are used as the boundary conditions for the analytical model to compute the energy release rate. The critical energy release rate values obtained from post-production package specimens are obtained to be lower than those laboratory specimens

Using SoC Online Correction Method Based on Parameter Identification to Optimize the Operation Range of NI-MH Battery for Electric Boat

Directory of Open Access Journals (Sweden)

Bumin Meng

2018-03-01

Full Text Available This paper discusses a design of a Battery Management System (BMS solution for extending the life of Nickel-Metal Hydride (NI-MH battery. Combined with application of electric boat, a State of Charge (SoC optimal operation range control method based on high precision energy metering and online SoC correction is proposed. Firstly, a power metering scheme is introduced to reduce the original energy measurement error. Secondly, by establishing a model based parameter identification method and combining with Extended Kalman Filter (EKF method, the estimation accuracy of SoC is guaranteed. Finally, SoC optimal operation range control method is presented to make battery running in the optimal range. After two years of operation, the battery managed by proposed method has much better status, compared to batteries that use AH integral method and fixed SoC operating range. Considering the SoC estimation of NI-MH battery is more difficult becausing special electrical characteristics, proposed method also would have a very good reference value for other types of battery management.

InGaN quantum well epilayers morphological evolution under a wide range of MOCVD growth parameter sets

International Nuclear Information System (INIS)

Florescu, D.I.; Ting, S.M.; Merai, V.N.; Parekh, A.; Lee, D.S.; Armour, E.A.; Quinn, W.E.

2006-01-01

This study exemplifies the use of TappingMode trademark atomic force microscopy (AFM) surface morphology imaging to investigate and optimise the metalorganic chemical vapour deposition (MOCVD) growth conditions and post-growth stability of thin ( '' GaN templates grown on (0001) c-plane sapphire substrates. The morphological evolution of the InGaN material was studied utilising a DI3100 AFM tool. Surface morphology and its correlation with photoluminescence and X-ray diffraction results are discussed for every set of conditions employed. More specifically, the post-growth ambient exposure and thermal stability of the uncapped InGaN epilayers were investigated. In addition, the initial stage of subsequent GaN growth, which is an essential step towards the manufacture of LED active regions, was examined. Based on the above findings, a flexible MOCVD growth parameter space and improved LED constituent layer sequencing techniques have been established leading to more efficient and stable LED devices. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Instrumentation Technologies for Improving an Irradiation Testing of Nuclear Fuels and Materials at the HANARO

International Nuclear Information System (INIS)

Kim, Bong Goo; Park, Sung Jae; Choo, Ki Nam

2011-01-01

Over 50 years of nuclear fuels and materials irradiation testing has led to many countries developing significant improvements in instrumentation to monitor physical parameters and to control the test conditions in Materials Test Reactors (MTRs) or research reactors. Recent effort to deploy new fuels and materials in existing and advanced reactors has increased the demand for well-instrumented irradiation tests. Specifically, demand has increased for tests with sensors capable of providing real-time measurement of key parameters, such as temperature, geometry changes, thermal conductivity, fission gas release, cracking, coating buildup, thermal and fast flux, etc. This review paper documents the current state of instrumentation technologies in MTRs in the world and summarizes on-going research efforts to deploy new sensors. There is increased interest to irradiate new materials and reactor fuels for advanced PWRs and the Gen-IV reactor systems, such as SFRs (Sodium-cooled Fast Reactors), VHTRs (Very-High-Temperature Reactors), SCWRs (Supercritical-Water-cooled Reactors) and GFRs (Gas-cooled Fast Reactor). This review documents the current state of instrumentation technologies in MTRs in the world, identifies challenges faced by previous testing methods and how these challenges were overcome. A wide range of sensors are available to measure key parameters of interest during fuels and materials irradiations in MTRs. Such sensors must be reliable, small size, highly accurate, and able to withstand harsh conditions. On-going development efforts are focusing on providing MTR users a wider range of parameter measurements with increased accuracy. In addition, development efforts are focusing on reducing the impact of sensor on measurements by reducing sensor size. This report includes not only status of instrumentation using research reactors in the world to irradiate nuclear fuels and materials but also future directions relating to instrumentation technologies for

Effects of Inhomogeneity and Thickness Parameters on the Elastic Response of a Pressurized Hyperbolic Annulus/Disc Made of Functionally Graded Material

Directory of Open Access Journals (Sweden)

Vebil Yıldırım

2017-10-01

Full Text Available A broad parametric study is carried out to investigate the effects of both the inhomogeneity parameter, and a profile index of Stodola’s hyperbolic function on the static response of such structures subjected to both the inner and outer pressures. The investigation is based on the analytical formulas lately published by the author. The effects of those parameters on the variation of the radial displacement, the radial and hoop stresses are all graphically illustrated for an annulus pressurized at its both surfaces. It is observed that, especially, the variation of the hoop stress in radial coordinate is closely sensible to variation of those parameters. For the chosen problems it was observed that one of two materials whose Young’s modulus is higher than the other is better to locate at the inner surface of the disc having divergent profile to get reasonable maximum hoop stresses. However much smaller radial displacements may be obtained by using positive inhomogeneity indexes for all discs whose surfaces host a material whose Young’s modulus is smaller than the other. To reach a final decision, analytical formulas such as those used in the present study together with a failure criteria such as Von Mises and Tresca become indispensable means in a design process.

High strength Al–Al2O3p composites: Optimization of extrusion parameters

DEFF Research Database (Denmark)

Luan, B.F.; Hansen, Niels; Godfrey, A.

2011-01-01

Composite aluminium alloys reinforced with Al2O3p particles have been produced by squeeze casting followed by hot extrusion and a precipitation hardening treatment. Good mechanical properties can be achieved, and in this paper we describe an optimization of the key processing parameters...... on an investigation of their mechanical properties and microstructure, as well as on the surface quality of the extruded samples. The evaluation shows that material with good strength, though with limited ductility, can be reliably obtained using a production route of squeeze casting, followed by hot extrusion....... The parameters investigated are the extrusion temperature, the extrusion rate and the extrusion ratio. The materials chosen are AA 2024 and AA 6061, each reinforced with 30vol.% Al2O3 particles of diameter typically in the range from 0.15 to 0.3μm. The extruded composites have been evaluated based...

Geoelectrical Measurement of Multi-Scale Mass Transfer Parameters

Energy Technology Data Exchange (ETDEWEB)

Day-Lewis, Frederick; Singha, Kamini; Haggerty, Roy; Johnson, Tim; Binley, Andrew; Lane, John

2014-01-16

Mass transfer affects contaminant transport and is thought to control the efficiency of aquifer remediation at a number of sites within the Department of Energy (DOE) complex. An improved understanding of mass transfer is critical to meeting the enormous scientific and engineering challenges currently facing DOE. Informed design of site remedies and long-term stewardship of radionuclide-contaminated sites will require new cost-effective laboratory and field techniques to measure the parameters controlling mass transfer spatially and across a range of scales. In this project, we sought to capitalize on the geophysical signatures of mass transfer. Previous numerical modeling and pilot-scale field experiments suggested that mass transfer produces a geoelectrical signature—a hysteretic relation between sampled (mobile-domain) fluid conductivity and bulk (mobile + immobile) conductivity—over a range of scales relevant to aquifer remediation. In this work, we investigated the geoelectrical signature of mass transfer during tracer transport in a series of controlled experiments to determine the operation of controlling parameters, and also investigated the use of complex-resistivity (CR) as a means of quantifying mass transfer parameters in situ without tracer experiments. In an add-on component to our grant, we additionally considered nuclear magnetic resonance (NMR) to help parse mobile from immobile porosities. Including the NMR component, our revised study objectives were to: 1. Develop and demonstrate geophysical approaches to measure mass-transfer parameters spatially and over a range of scales, including the combination of electrical resistivity monitoring, tracer tests, complex resistivity, nuclear magnetic resonance, and materials characterization; and 2. Provide mass-transfer estimates for improved understanding of contaminant fate and transport at DOE sites, such as uranium transport at the Hanford 300 Area. To achieve our objectives, we implemented a 3

Parametric analysis and design of a screw extruder for slightly non-Newtonian (pseudoplastic materials

Directory of Open Access Journals (Sweden)

J.I. Orisaleye

2018-04-01

Full Text Available Extruders have found application in the food, polymer and pharmaceutical industries. Rheological characteristics of materials are important in the specification of design parameters of screw extruders. Biopolymers, which consist of proteins, nucleic acids and polysaccharides, are shear-thinning (pseudoplastic within normal operating ranges. However, analytical models to predict and design screw extruders for non-Newtonian pseudoplastic materials are rare. In this study, an analytical model suitable to design a screw extruder for slightly non-Newtonian materials was developed. The model was used to predict the performance of the screw extruder while processing materials with power law indices slightly deviating from unity (the Newtonian case. Using non-dimensional analysis, the effects of design and operational parameters were investigated. Expressions to determine the optimum channel depth and helix angle were also derived. The model is capable of predicting the performance of the screw extruder within the range of power law indices considered (1/2⩽n⩽1. The power law index influences the choice of optimum channel depth and helix angle of the screw extruder. Keywords: Screw extruder, Slightly non-Newtonian, Shear-thinning, Pseudoplastic, Biopolymer, Power law

Preliminary performance assessment for the Waste Isolation Pilot Plant, December 1992. Volume 3, Model parameters: Sandia WIPP Project

Energy Technology Data Exchange (ETDEWEB)

1992-12-29

This volume documents model parameters chosen as of July 1992 that were used by the Performance Assessment Department of Sandia National Laboratories in its 1992 preliminary performance assessment of the Waste Isolation Pilot Plant (WIPP). Ranges and distributions for about 300 modeling parameters in the current secondary data base are presented in tables for the geologic and engineered barriers, global materials (e.g., fluid properties), and agents that act upon the WIPP disposal system such as climate variability and human-intrusion boreholes. The 49 parameters sampled in the 1992 Preliminary Performance Assessment are given special emphasis with tables and graphics that provide insight and sources of data for each parameter.

Normal ranges and test-retest reproducibility of flow and velocity parameters in intracranial arteries measured with phase-contrast magnetic resonance imaging

International Nuclear Information System (INIS)

Correia de Verdier, Maria; Wikstroem, Johan

2016-01-01

The purpose of the present study was to investigate normal ranges and test-retest reproducibility of phase-contrast MRI (PC-MRI)-measured flow and velocity parameters in intracranial arteries. Highest flow (HF), lowest flow (LF), peak systolic velocity (PSV), and end diastolic velocity (EDV) were measured at two dates in the anterior (ACA), middle (MCA), and posterior (PCA) cerebral arteries of 30 healthy volunteers using two-dimensional PC-MRI at 3 T. Least detectable difference (LDD) was calculated. In the left ACA, HF was (mean (range, LDD)) 126 ml/min (36-312, 59 %), LF 61 ml/min (0-156, 101 %), PSV 64 cm/s (32-141, 67 %), and EDV 35 cm/s (18-55, 42 %); in the right ACA, HF was 154 ml/min (42-246, 49 %), LF 77 ml/min (0-156, 131 %), PSV 75 cm/s (26-161, 82 %), and EDV 39 cm/s (7-59, 67 %). In the left MCA, HF was 235 ml/min (126-372, 35 %), LF 116 ml/min (42-186, 48 %), PSV 90 cm/s (55-183, 39 %), and EDV 46 cm/s (20-66, 28 %); in the right MCA, HF was 238 ml/min (162-342, 44 %), LF 120 ml/min (72-216, 48 %), PSV 88 cm/s (55-141, 35 %), and EDV 45 cm/s (26-67, 23 %). In the left PCA, HF was 108 ml/min (42-168, 54 %), LF 53 ml/min (18-108, 64 %), PSV 50 cm/s (24-77, 63 %), and EDV 28 cm/s (14-40, 45 %); in the right PCA, HF was 98 ml/min (30-162, 49 %), LF 49 ml/min (12-84, 55 %), PSV 47 cm/s (27-88, 59 %), and EDV 27 cm/s (16-41, 45 %). PC-MRI-measured flow and velocity parameters in the main intracranial arteries have large normal ranges. Reproducibility is highest in MCA. (orig.)

Normal ranges and test-retest reproducibility of flow and velocity parameters in intracranial arteries measured with phase-contrast magnetic resonance imaging

Energy Technology Data Exchange (ETDEWEB)

Correia de Verdier, Maria; Wikstroem, Johan [Uppsala University Hospital, Department of Radiology, Uppsala University, Uppsala (Sweden)

2016-05-15

The purpose of the present study was to investigate normal ranges and test-retest reproducibility of phase-contrast MRI (PC-MRI)-measured flow and velocity parameters in intracranial arteries. Highest flow (HF), lowest flow (LF), peak systolic velocity (PSV), and end diastolic velocity (EDV) were measured at two dates in the anterior (ACA), middle (MCA), and posterior (PCA) cerebral arteries of 30 healthy volunteers using two-dimensional PC-MRI at 3 T. Least detectable difference (LDD) was calculated. In the left ACA, HF was (mean (range, LDD)) 126 ml/min (36-312, 59 %), LF 61 ml/min (0-156, 101 %), PSV 64 cm/s (32-141, 67 %), and EDV 35 cm/s (18-55, 42 %); in the right ACA, HF was 154 ml/min (42-246, 49 %), LF 77 ml/min (0-156, 131 %), PSV 75 cm/s (26-161, 82 %), and EDV 39 cm/s (7-59, 67 %). In the left MCA, HF was 235 ml/min (126-372, 35 %), LF 116 ml/min (42-186, 48 %), PSV 90 cm/s (55-183, 39 %), and EDV 46 cm/s (20-66, 28 %); in the right MCA, HF was 238 ml/min (162-342, 44 %), LF 120 ml/min (72-216, 48 %), PSV 88 cm/s (55-141, 35 %), and EDV 45 cm/s (26-67, 23 %). In the left PCA, HF was 108 ml/min (42-168, 54 %), LF 53 ml/min (18-108, 64 %), PSV 50 cm/s (24-77, 63 %), and EDV 28 cm/s (14-40, 45 %); in the right PCA, HF was 98 ml/min (30-162, 49 %), LF 49 ml/min (12-84, 55 %), PSV 47 cm/s (27-88, 59 %), and EDV 27 cm/s (16-41, 45 %). PC-MRI-measured flow and velocity parameters in the main intracranial arteries have large normal ranges. Reproducibility is highest in MCA. (orig.)

New evaluation of 238U neutron resonance parameters

International Nuclear Information System (INIS)

Derrien, Herve; Leal, Luiz C.; Larson, Nancy M.

2003-01-01

The neutron resonance parameters of 238 U were obtained in the energy range 1 keV to 20 keV from a SAMMY Reich-Moore analysis of high resolution transmission measurements performed at ORELA. In the energy range 1 keV to 10 keV, the analysis used as prior values the ENDF/B-VI resonance parameters. The analysis in the energy range 10 keV to 20 keV resulted in the creation of a set of resonance parameters for the representation of the cross section in this energy range. The results are compared to the ENDF/B-VI evaluation. Some statistical properties of the new resonance parameters are examined. (author)

Effect of low-Z absorber's thickness on gamma-ray shielding parameters

Energy Technology Data Exchange (ETDEWEB)

Mann, Kulwinder Singh, E-mail: ksmann6268@gmail.com [Department of Applied Sciences, Punjab Technical University, Kapurthala 144601 (India); Department of Physics, D.A.V. College, Bathinda 151001, Punjab (India); Heer, Manmohan Singh [Department of Physics, Kanya Maha Vidyalaya, Jalandhar 144001 (India); Rani, Asha [Department of Applied Sciences, Ferozpur College of Engineering and Technology, Ferozshah, Ferozpur 142052 (India)

2015-10-11

Gamma ray shielding behaviour of any material can be studied by various interaction parameters such as total mass attenuation coefficient (μ{sub m}); half value layer (HVL); tenth value layer (TVL); effective atomic number (Z{sub eff}), electron density (N{sub el}), effective atomic weight (A{sub eff}) and buildup factor. For gamma rays, the accurate measurements of μ{sub m} (cm{sup 2} g{sup −1}) theoretically require perfect narrow beam irradiation geometry. However, the practical geometries used for the experimental investigations deviate from perfect-narrowness thereby the multiple scattered photons cause systematic errors in the measured values of μ{sub m}. Present investigation is an attempt to find the optimum value of absorber thickness (low-Z) for which these errors are insignificant and acceptable. Both experimental and theoretical calculations have been performed to investigate the effect of absorber's thickness on μ{sub m} of six low-Z (10materials (cement-black; cement-white; clay; red-mud; lime-stone and plaster of paris) at gamma-ray energies 661.66 keV, 1173.24 keV and 1332.50 keV. A computer program (GRIC2-toolkit) was designed for theoretical evaluation of shielding parameters of any material. Good agreement of theoretical and measured values of μ{sub m} was observed for all absorbers with thickness ≤0.5 mean free paths, thus considered it as optimum thickness for low-Z materials in the selected energy range. White cement was found to possess maximum shielding effectiveness for the selected gamma rays. - Highlights: • Optimum thickness value is 0.5 mfp for low-Z absorbers in energy range 662–1332 keV. • For accurate measurement of μ{sub m} absorber's thickness should be ≤optimum thickness. • GRIC2-toolkit is useful for γ-ray shielding analysis of composite materials.

Energy absorption buildup factors for thermoluminescent dosimetric materials and their tissue equivalence

DEFF Research Database (Denmark)

Manohara, S.R.; Hanagodimath, S.M.; Gerward, Leif

2010-01-01

Gamma ray energy-absorption buildup factors were computed using the five-parameter geometric progression (G-P) fitting formula for seven thermoluminescent dosimetric (TLD) materials in the energy range 0.015-15 MeV, and for penetration depths up to 40 mfp (mean free path). The generated energy-absorption...

Kalman filtration of radiation monitoring data from atmospheric dispersion of radioactive materials

DEFF Research Database (Denmark)

Drews, M.; Lauritzen, B.; Madsen, H.

2004-01-01

A Kalman filter method using off-site radiation monitoring data is proposed as a tool for on-line estimation of the source term for short-range atmospheric dispersion of radioactive materials. The method is based on the Gaussian plume model, in which the plume parameters including the source term...

Analysis of Thomsen parameters for finely layered VTI media

International Nuclear Information System (INIS)

Berryman, J.G.; Berge, P.A.

1997-01-01

The range of Thomsen's anisotropy parameters ε and δ for vertical transversely isotropic (VTI) media when the anisotropy is due to fine layering of isotropic elas-tic materials is considered. We show that ε lies in the range -3/8 ≤ ε ≤ 1/2 v p 2 > p-2 >-1 for finely layered media having constant density; smaller positive and all negative values of ε occur for media with large fluctuations in the Lamacute e parameter λ We show that sign(δ) = sign ( p -2 > - s -2 > s 2 /v p 2 >) for constant density media, so δ can be either positive or negative. Among all theoretically possible random media, posi-tive and negative δ are equally likely in finely layered media limited to two types of constituent layers. Lay-ered media having large fluctuations in Lamacute e λ are the ones most likely to have positive δ. Since Gassmann's results for fluid-saturated porous media show that the effects of fluids influence only the λ Lamacute e constant, not the shear modulus μ, these results suggest that positive δ occurring together with positive but small ε may be indicative of changing fluid content in layered earth

Influence of raw material properties upon critical quality attributes of continuously produced granules and tablets

DEFF Research Database (Denmark)

Fonteyne, Margot; Wickström, Henrika; Peeters, Elisabeth

2014-01-01

over a range of raw material attributes, manufacturing process options and process parameters. This fits further into the Process Analytical Technology (PAT) and Quality by Design (QbD) framework. The present study evaluates the effect of variation in critical raw material properties on the critical......-Lactose-PVP (30-67.5-2.5%) was used as model formulation. Seven different grades of theophylline were granulated. Afterward, the obtained granules were tableted. Both the characteristics of granules and tablets were determined. The results show that differences in raw material properties both affect...... quality attributes of granules and tablets, produced by a continuous from-powder-to-tablet wet granulation line. The granulation process parameters were kept constant to examine the differences in the end product quality caused by the variability of the raw materials properties only. Theophylline...

The relationship of microstructure and temperature to fracture mechanics parameters in reaction bonded silicon nitride

International Nuclear Information System (INIS)

Jennings, H.M.; Dalgleish, B.J.; Pratt, P.L.

1978-01-01

The development of physical properties in reaction bonded silicon nitride has been investigated over a range of temperatures and correlated with microstructure. Fracture mechanics parameters, elastic moduli, strength and critical defect size have been determined. The nitrided microstructure is shown to be directly related to these observed properties and these basic relationships can be used to produce material with improved properties. (orig.) [de

Parameters affecting mechanical and thermal responses in bone drilling: A review.

Science.gov (United States)

Lee, JuEun; Chavez, Craig L; Park, Joorok

2018-04-11

Surgical bone drilling is performed variously to correct bone fractures, install prosthetics, or for therapeutic treatment. The primary concern in bone drilling is to extract donor bone sections and create receiving holes without damaging the bone tissue either mechanically or thermally. We review current results from experimental and theoretical studies to investigate the parameters related to such effects. This leads to a comprehensive understanding of the mechanical and thermal aspects of bone drilling to reduce their unwanted complications. This review examines the important bone-drilling parameters of bone structure, drill-bit geometry, operating conditions, and material evacuation, and considers the current techniques used in bone drilling. We then analyze the associated mechanical and thermal effects and their contributions to bone-drilling performance. In this review, we identify a favorable range for each parameter to reduce unwanted complications due to mechanical or thermal effects. Copyright © 2018 Elsevier Ltd. All rights reserved.

Optimal Laser Phototherapy Parameters for Pain Relief.

Science.gov (United States)

Kate, Rohit J; Rubatt, Sarah; Enwemeka, Chukuka S; Huddleston, Wendy E

2018-03-27

Studies on laser phototherapy for pain relief have used parameters that vary widely and have reported varying outcomes. The purpose of this study was to determine the optimal parameter ranges of laser phototherapy for pain relief by analyzing data aggregated from existing primary literature. Original studies were gathered from available sources and were screened to meet the pre-established inclusion criteria. The included articles were then subjected to meta-analysis using Cohen's d statistic for determining treatment effect size. From these studies, ranges of the reported parameters that always resulted into large effect sizes were determined. These optimal ranges were evaluated for their accuracy using leave-one-article-out cross-validation procedure. A total of 96 articles met the inclusion criteria for meta-analysis and yielded 232 effect sizes. The average effect size was highly significant: d = +1.36 (confidence interval [95% CI] = 1.04-1.68). Among all the parameters, total energy was found to have the greatest effect on pain relief and had the most prominent optimal ranges of 120-162 and 15.36-20.16 J, which always resulted in large effect sizes. The cross-validation accuracy of the optimal ranges for total energy was 68.57% (95% CI = 53.19-83.97). Fewer and less-prominent optimal ranges were obtained for the energy density and duration parameters. None of the remaining parameters was found to be independently related to pain relief outcomes. The findings of meta-analysis indicate that laser phototherapy is highly effective for pain relief. Based on the analysis of parameters, total energy can be optimized to yield the largest effect on pain relief.

Estimation of effect of hydrogen on the parameters of magnetoacoustic emission signals

Science.gov (United States)

Skalskyi, Valentyn; Stankevych, Olena; Dubytskyi, Olexandr

2018-05-01

The features of the magnetoacoustic emission (MAE) signals during magnetization of structural steels with the different degree of hydrogenating were investigated by the wavelet transform. The dominant frequency ranges of MAE signals for the different magnetic field strength were determined using Discrete Wavelet Transform (DWT), and the energy and spectral parameters of MAE signals were determined using Continuous Wavelet Transform (CWT). The characteristic differences of the local maximums of signals according to energy, bandwidth, duration and frequency were found. The methodology of estimation of state of local degradation of materials by parameters of wavelet transform of MAE signals was proposed. This methodology was approbated for investigate of state of long-time exploitations structural steels of oil and gas pipelines.

Bowtie filters for dedicated breast CT: Analysis of bowtie filter material selection

Energy Technology Data Exchange (ETDEWEB)

Kontson, Kimberly, E-mail: Kimberly.Kontson@fda.hhs.gov; Jennings, Robert J. [Department of Bioengineering, University of Maryland, College Park, Maryland 20742 and Division of Imaging and Applied Mathematics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, U.S. Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993 (United States)

2015-09-15

Purpose: For a given bowtie filter design, both the selection of material and the physical design control the energy fluence, and consequently the dose distribution, in the object. Using three previously described bowtie filter designs, the goal of this work is to demonstrate the effect that different materials have on the bowtie filter performance measures. Methods: Three bowtie filter designs that compensate for one or more aspects of the beam-modifying effects due to the differences in path length in a projection have been designed. The nature of the designs allows for their realization using a variety of materials. The designs were based on a phantom, 14 cm in diameter, composed of 40% fibroglandular and 60% adipose tissue. Bowtie design #1 is based on single material spectral matching and produces nearly uniform spectral shape for radiation incident upon the detector. Bowtie design #2 uses the idea of basis-material decomposition to produce the same spectral shape and intensity at the detector, using two different materials. With bowtie design #3, it is possible to eliminate the beam hardening effect in the reconstructed image by adjusting the bowtie filter thickness so that the effective attenuation coefficient for every ray is the same. Seven different materials were chosen to represent a range of chemical compositions and densities. After calculation of construction parameters for each bowtie filter design, a bowtie filter was created using each of these materials (assuming reasonable construction parameters were obtained), resulting in a total of 26 bowtie filters modeled analytically and in the PENELOPE Monte Carlo simulation environment. Using the analytical model of each bowtie filter, design profiles were obtained and energy fluence as a function of fan-angle was calculated. Projection images with and without each bowtie filter design were also generated using PENELOPE and reconstructed using FBP. Parameters such as dose distribution, noise uniformity

Bowtie filters for dedicated breast CT: Analysis of bowtie filter material selection

International Nuclear Information System (INIS)

Kontson, Kimberly; Jennings, Robert J.

2015-01-01

Purpose: For a given bowtie filter design, both the selection of material and the physical design control the energy fluence, and consequently the dose distribution, in the object. Using three previously described bowtie filter designs, the goal of this work is to demonstrate the effect that different materials have on the bowtie filter performance measures. Methods: Three bowtie filter designs that compensate for one or more aspects of the beam-modifying effects due to the differences in path length in a projection have been designed. The nature of the designs allows for their realization using a variety of materials. The designs were based on a phantom, 14 cm in diameter, composed of 40% fibroglandular and 60% adipose tissue. Bowtie design #1 is based on single material spectral matching and produces nearly uniform spectral shape for radiation incident upon the detector. Bowtie design #2 uses the idea of basis-material decomposition to produce the same spectral shape and intensity at the detector, using two different materials. With bowtie design #3, it is possible to eliminate the beam hardening effect in the reconstructed image by adjusting the bowtie filter thickness so that the effective attenuation coefficient for every ray is the same. Seven different materials were chosen to represent a range of chemical compositions and densities. After calculation of construction parameters for each bowtie filter design, a bowtie filter was created using each of these materials (assuming reasonable construction parameters were obtained), resulting in a total of 26 bowtie filters modeled analytically and in the PENELOPE Monte Carlo simulation environment. Using the analytical model of each bowtie filter, design profiles were obtained and energy fluence as a function of fan-angle was calculated. Projection images with and without each bowtie filter design were also generated using PENELOPE and reconstructed using FBP. Parameters such as dose distribution, noise uniformity

Thermodynamic estimation: Ionic materials

International Nuclear Information System (INIS)

Glasser, Leslie

2013-01-01

Thermodynamics establishes equilibrium relations among thermodynamic parameters (“properties”) and delineates the effects of variation of the thermodynamic functions (typically temperature and pressure) on those parameters. However, classical thermodynamics does not provide values for the necessary thermodynamic properties, which must be established by extra-thermodynamic means such as experiment, theoretical calculation, or empirical estimation. While many values may be found in the numerous collected tables in the literature, these are necessarily incomplete because either the experimental measurements have not been made or the materials may be hypothetical. The current paper presents a number of simple and relible estimation methods for thermodynamic properties, principally for ionic materials. The results may also be used as a check for obvious errors in published values. The estimation methods described are typically based on addition of properties of individual ions, or sums of properties of neutral ion groups (such as “double” salts, in the Simple Salt Approximation), or based upon correlations such as with formula unit volumes (Volume-Based Thermodynamics). - Graphical abstract: Thermodynamic properties of ionic materials may be readily estimated by summation of the properties of individual ions, by summation of the properties of ‘double salts’, and by correlation with formula volume. Such estimates may fill gaps in the literature, and may also be used as checks of published values. This simplicity arises from exploitation of the fact that repulsive energy terms are of short range and very similar across materials, while coulombic interactions provide a very large component of the attractive energy in ionic systems. Display Omitted - Highlights: • Estimation methods for thermodynamic properties of ionic materials are introduced. • Methods are based on summation of single ions, multiple salts, and correlations. • Heat capacity, entropy

Improving the thermal stability and electrical parameters of a liquid crystalline material 4-n-(nonyloxy) benzoic acid by using Li ion beam irradiation

Science.gov (United States)

Kumar, Satendra; Verma, Rohit; Dwivedi, Aanchal; Dhar, R.; Tripathi, Ambuj

2018-05-01

Li ion beam irradiation studies on a liquid crystalline material 4-n-(nonyloxy) benzoic acid (NOBA) have been carried out. The material has phase sequence of I-N-SmC-Cr. Thermodynamic studies demonstrate that an irradiation fluence of 1×1013 ions-cm-2 results in the increased thermal stability of the smectic C (SmC) phase of the material. Dielectric measurements illustrate that the transverse component of the dielectric permittivity and hence the dielectric anisotropy of the material in the nematic (N) and SmC phases are increased as compared to those of the pure material due to irradiation. UV-Visible spectrum of the irradiated material shows an additional peak along with the peak of the pure material. The observed change in the thermodynamic and electrical parameters is attributed to the conversion of some of the dimers of NOBA to monomers of NOBA due to irradiation.

Data-driven techniques to estimate parameters in a rate-dependent ferromagnetic hysteresis model

International Nuclear Information System (INIS)

Hu Zhengzheng; Smith, Ralph C.; Ernstberger, Jon M.

2012-01-01

The quantification of rate-dependent ferromagnetic hysteresis is important in a range of applications including high speed milling using Terfenol-D actuators. There exist a variety of frameworks for characterizing rate-dependent hysteresis including the magnetic model in Ref. , the homogenized energy framework, Preisach formulations that accommodate after-effects, and Prandtl-Ishlinskii models. A critical issue when using any of these models to characterize physical devices concerns the efficient estimation of model parameters through least squares data fits. A crux of this issue is the determination of initial parameter estimates based on easily measured attributes of the data. In this paper, we present data-driven techniques to efficiently and robustly estimate parameters in the homogenized energy model. This framework was chosen due to its physical basis and its applicability to ferroelectric, ferromagnetic and ferroelastic materials.

Development of a Tomography Technique for Assessment of the Material Condition of Concrete Using Optimized Elastic Wave Parameters

Directory of Open Access Journals (Sweden)

Hwa Kian Chai

2016-04-01

Full Text Available Concrete is the most ubiquitous construction material. Apart from the fresh and early age properties of concrete material, its condition during the structure life span affects the overall structural performance. Therefore, development of techniques such as non-destructive testing which enable the investigation of the material condition, are in great demand. Tomography technique has become an increasingly popular non-destructive evaluation technique for civil engineers to assess the condition of concrete structures. In the present study, this technique is investigated by developing reconstruction procedures utilizing different parameters of elastic waves, namely the travel time, wave amplitude, wave frequency, and Q-value. In the development of algorithms, a ray tracing feature was adopted to take into account the actual non-linear propagation of elastic waves in concrete containing defects. Numerical simulation accompanied by experimental verifications of wave motion were conducted to obtain wave propagation profiles in concrete containing honeycomb as a defect and in assessing the tendon duct filling of pre-stressed concrete (PC elements. The detection of defects by the developed tomography reconstruction procedures was evaluated and discussed.

Material recognition with the Medipix photon counting colour X-ray system

Energy Technology Data Exchange (ETDEWEB)

Norlin, B. E-mail: borje.norlin@mh.se; Manuilskiy, A.; Nilsson, H.-E.; Froejdh, C

2004-09-21

An energy sensitive imaging system like Medipix1 has proved to be promising in distinguishing different materials in an X-ray image of an object. We propose a general method utilising X-ray energy information for material recognition. For objects where the thickness of the materials is unknown, a convenient material parameter to identify is K={alpha}{sub 1}/{alpha}{sub 2}, which is the ratio of the logarithms of the measured transmissions ln(t{sub 1})/ln(t{sub 2}). If a database of the parameter K for different materials and energies is created, this method can be used for material recognition independent of the thickness of the materials. Series of images of an object consisting of aluminium and silicon were taken with different energy thresholds. The X-ray absorption for silicon and aluminium is very similar for the range 40-60 keV and only differs for lower energies. The results show that it is possible to distinguish between aluminium and silicon on images achieved by Medipix1 using a standard dental source. By decreasing the spatial resolution a better contrast between the materials was achieved. The resolution of contrasts shown by the histograms was close to the limit of the system due to the statistical noise of the signal.

Reliability of electrode wear compensation based on material removal per discharge in micro EDM milling

DEFF Research Database (Denmark)

Bissacco, Giuliano; Tristo, G.; Hansen, Hans Nørgaard

2013-01-01

This paper investigates the reliability of workpiece material removal per discharge (MRD) estimation for application in electrode wear compensation based on workpiece material removal. An experimental investigation involving discharge counting and automatic on the machine measurement of removed...... material volume was carried out in a range of process parameters settings from fine finishing to roughing. MRD showed a decreasing trend with the progress of the machining operation, reaching stabilization after a number of machined layers. Using the information on MRD and discharge counting, a material...

Effect of Cr4+ impurities in Nd:Cr:GSGG and Nd:Cr:YAG laser materials on parameters of lasers at solar pumping

International Nuclear Information System (INIS)

Payziyev, Sh.D.; Bakhramov, S.A.; Shayimov, F.F.; Fayziev, A.Sh.

2015-01-01

The analysis of an effect of Cr 4+ impurity ions, existent in Nd 3+ :Cr 3+ :GSGG and Nd 3+ :Cr 3+ :YAG laser materials on output parameters of solar pumped lasers is carried out by modeling of lasing process at solar pumping. (authors)

Hydrogen and deuterium transport and inventory parameters through W and W-alloys for fusion reactor applications

Science.gov (United States)

Benamati, G.; Serra, E.; Wu, C. H.

2000-12-01

The aim of this work is to measure the hydrogen/deuterium transport and inventory parameters in relevant structural and/or armour materials for the International Thermonuclear Experimental Reactor (ITER) divertor such as W and W-alloys. The W-alloys: W, W + 1% La 2O 3 and W + 5% Re have been investigated. The materials were supplied from the Metallwerk Plansee GmbH (Austria). Measurements were conducted using a time-dependent permeation method over the temperature range 673-873 K with hydrogen and deuterium pressures in the range 10-100 kPa (100-1000 mbar). The samples were also characterized using optical microscopy, SEM and energy dispersive spectroscopy (EDS) in order to investigate the composition, microstructure and morphology of the surfaces and cross-sections through the samples.

New evaluation parameter for wearable thermoelectric generators

Science.gov (United States)

Wijethunge, Dimuthu; Kim, Woochul

2018-04-01

Wearable devices constitute a key application area for thermoelectric devices. However, owing to new constraints in wearable applications, a few conventional device optimization techniques are not appropriate and material evaluation parameters, such as figure of merit (zT) and power factor (PF), tend to be inadequate. We illustrated the incompleteness of zT and PF by performing simulations and considering different thermoelectric materials. The results indicate a weak correlation between device performance and zT and PF. In this study, we propose a new evaluation parameter, zTwearable, which is better suited for wearable applications compared to conventional zT. Owing to size restrictions, gap filler based device optimization is extremely critical in wearable devices. With respect to the occasions in which gap fillers are used, expressions for power, effective thermal conductivity (keff), and optimum load electrical ratio (mopt) are derived. According to the new parameters, the thermal conductivity of the material has become much more critical now. The proposed new evaluation parameter, namely, zTwearable, is extremely useful in the selection of an appropriate thermoelectric material among various candidates prior to the commencement of the actual design process.

Phase Change Material Selection for Thermal Energy Storage at High Temperature Range between 210 °C and 270 °C

Directory of Open Access Journals (Sweden)

José Miguel Maldonado

2018-04-01

Full Text Available The improvement of thermal energy storage systems implemented in solar technologies increases not only their performance but also their dispatchability and competitiveness in the energy market. Latent heat thermal energy storage systems are one of those storing methods. Therefore, the need of finding the best materials for each application becomes an appealing research subject. The main goal of this paper is to find suitable and economically viable materials able to work as phase change material (PCM within the temperature range of 210–270 °C and endure daily loading and unloading processes in a system with Fresnel collector and an organic Rankine cycle (ORC. Twenty-six materials have been tested and characterized in terms of their thermophysical conditions, thermal and cycling stability, and health hazard. Two materials out of the 26 candidates achieved the last stage of the selection process. However, one of the two finalists would require an inert working atmosphere, which would highly increase the cost for the real scale application. This leads to a unique suitable material, solar salt (40 wt % KNO3/60 wt % NaNO3.

Radiation attenuation by lead and nonlead materials used in radiation shielding garments

International Nuclear Information System (INIS)

McCaffrey, J. P.; Shen, H.; Downton, B.; Mainegra-Hing, E.

2007-01-01

The attenuating properties of several types of lead (Pb)-based and non-Pb radiation shielding materials were studied and a correlation was made of radiation attenuation, materials properties, calculated spectra and ambient dose equivalent. Utilizing the well-characterized x-ray and gamma ray beams at the National Research Council of Canada, air kerma measurements were used to compare a variety of commercial and pre-commercial radiation shielding materials over mean energy ranges from 39 to 205 keV. The EGSnrc Monte Carlo user code cavity.cpp was extended to provide computed spectra for a variety of elements that have been used as a replacement for Pb in radiation shielding garments. Computed air kerma values were compared with experimental values and with the SRS-30 catalogue of diagnostic spectra available through the Institute of Physics and Engineering in Medicine Report 78. In addition to garment materials, measurements also included pure Pb sheets, allowing direct comparisons to the common industry standards of 0.25 and 0.5 mm 'lead equivalent'. The parameter 'lead equivalent' is misleading, since photon attenuation properties for all materials (including Pb) vary significantly over the energy spectrum, with the largest variations occurring in the diagnostic imaging range. Furthermore, air kerma measurements are typically made to determine attenuation properties without reference to the measures of biological damage such as ambient dose equivalent, which also vary significantly with air kerma over the diagnostic imaging energy range. A single material or combination cannot provide optimum shielding for all energy ranges. However, appropriate choice of materials for a particular energy range can offer significantly improved shielding per unit mass over traditional Pb-based materials

Close-range photogrammetry for aircraft quality control

Science.gov (United States)

Schwartz, D. S.

Close range photogrammetry is applicable to quality assurance inspections, design data acquisition, and test management support tasks, yielding significant cost avoidance and increased productivity. An understanding of mensuration parameters and their related accuracies is fundamental to the successful application of industrial close range photogrammetry. Attention is presently given to these parameters and to the use of computer modelling as an aid to the photogrammetric entrepreneur in industry. Suggested improvements to cameras and film readers for industrial applications are discussed.

Multi-scale Material Parameter Identification Using LS-DYNA® and LS-OPT®

Energy Technology Data Exchange (ETDEWEB)

Stander, Nielen [Livermore Software Technology Corporation, CA (United States); Basudhar, Anirban [Livermore Software Technology Corporation, CA (United States); Basu, Ushnish [Livermore Software Technology Corporation, CA (United States); Gandikota, Imtiaz [Livermore Software Technology Corporation, CA (United States); Savic, Vesna [General Motors, Flint, MI (United States); Sun, Xin [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hu, XiaoHua [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Pourboghrat, Farhang [The Ohio State Univ., Columbus, OH (United States); Park, Taejoon [The Ohio State Univ., Columbus, OH (United States); Mapar, Aboozar [Michigan State Univ., East Lansing, MI (United States); Kumar, Sharvan [Brown Univ., Providence, RI (United States); Ghassemi-Armaki, Hassan [Brown Univ., Providence, RI (United States); Abu-Farha, Fadi [Clemson Univ., SC (United States)

2015-06-15

Ever-tightening regulations on fuel economy and carbon emissions demand continual innovation in finding ways for reducing vehicle mass. Classical methods for computational mass reduction include sizing, shape and topology optimization. One of the few remaining options for weight reduction can be found in materials engineering and material design optimization. Apart from considering different types of materials by adding material diversity, an appealing option in automotive design is to engineer steel alloys for the purpose of reducing thickness while retaining sufficient strength and ductility required for durability and safety. Such a project was proposed and is currently being executed under the auspices of the United States Automotive Materials Partnership (USAMP) funded by the Department of Energy. Under this program, new steel alloys (Third Generation Advanced High Strength Steel or 3GAHSS) are being designed, tested and integrated with the remaining design variables of a benchmark vehicle Finite Element model. In this project the principal phases identified are (i) material identification, (ii) formability optimization and (iii) multi-disciplinary vehicle optimization. This paper serves as an introduction to the LS-OPT methodology and therefore mainly focuses on the first phase, namely an approach to integrate material identification using material models of different length scales. For this purpose, a multi-scale material identification strategy, consisting of a Crystal Plasticity (CP) material model and a Homogenized State Variable (SV) model, is discussed and demonstrated. The paper concludes with proposals for integrating the multi-scale methodology into the overall vehicle design.

Comparison of nuclear irradiation parameters of fusion breeder materials in high flux fission test reactors and a fusion power demonstration reactor

International Nuclear Information System (INIS)

Fischer, U.; Herring, S.; Hogenbirk, A.; Leichtle, D.; Nagao, Y.; Pijlgroms, B.J.; Ying, A.

2000-01-01

Nuclear irradiation parameters relevant to displacement damage and burn-up of the breeder materials Li 2 O, Li 4 SiO 4 and Li 2 TiO 3 have been evaluated and compared for a fusion power demonstration reactor and the high flux fission test reactor (HFR), Petten, the advanced test reactor (ATR, INEL) and the Japanese material test reactor (JMTR, JAERI). Based on detailed nuclear reactor calculations with the MCNP Monte Carlo code and binary collision approximation (BCA) computer simulations of the displacement damage in the polyatomic lattices with MARLOWE, it has been investigated how well the considered HFRs can meet the requirements for a fusion power reactor relevant irradiation. It is shown that a breeder material irradiation in these fission test reactors is well suited in this regard when the neutron spectrum is well tailored and the 6 Li-enrichment is properly chosen. Requirements for the relevant nuclear irradiation parameters such as the displacement damage accumulation, the lithium burn-up and the damage production function W(T) can be met when taking into account these prerequisites. Irradiation times in the order of 2-3 full power years are necessary for the HFR to achieve the peak values of the considered fusion power Demo reactor blanket with regard to the burn-up and, at the same time, the dpa accumulation

Grain filling parameters and yield components in wheat

OpenAIRE

Brdar Milka; Kobiljski Borislav; Balalić-Kraljević Marija

2006-01-01

Grain yield of wheat (Triticum aestivum L.) is influenced by number of grains per unit area and grain weight, which is result of grain filling duration and rate. The aim of the study was to investigate the relationships between grain filling parameters in 4 wheat genotypes of different earliness and yield components. Nonlinear regression estimated and observed parameters were analyzed. Rang of estimated parameters corresponds to rang of observed parameters. Stepwise MANOVA indicated that the ...

Analytical threshold voltage modeling of ion-implanted strained-Si double-material double-gate (DMDG) MOSFETs

Science.gov (United States)

Goel, Ekta; Singh, Balraj; Kumar, Sanjay; Singh, Kunal; Jit, Satyabrata

2017-04-01

Two dimensional threshold voltage model of ion-implanted strained-Si double-material double-gate MOSFETs has been done based on the solution of two dimensional Poisson's equation in the channel region using the parabolic approximation method. Novelty of the proposed device structure lies in the amalgamation of the advantages of both the strained-Si channel and double-material double-gate structure with a vertical Gaussian-like doping profile. The effects of different device parameters (such as device channel length, gate length ratios, germanium mole fraction) and doping parameters (such as projected range, straggle parameter) on threshold voltage of the proposed structure have been investigated. It is observed that the subthreshold performance of the device can be improved by simply controlling the doping parameters while maintaining other device parameters constant. The modeling results show a good agreement with the numerical simulation data obtained by using ATLAS™, a 2D device simulator from SILVACO.

Influences of Cutting Speed and Material Mechanical Properties on Chip Deformation and Fracture during High-Speed Cutting of Inconel 718

Directory of Open Access Journals (Sweden)

Bing Wang

2018-03-01

Full Text Available The paper aims to investigate the influences of material constitutive and fracture parameters in addition to cutting speed on chip formation during high-speed cutting of Inconel 718. Finite element analyses for chip formation are conducted with Johnson–Cook constitutive and fracture models. Meanwhile, experiments of high-speed orthogonal cutting are performed to verify the simulation results with cutting speeds ranging from 50 m/min to 7000 m/min. The research indicates that the chip morphology transforms from serrated to fragmented at the cutting speed of 7000 m/min due to embrittlement of the workpiece material under ultra-high cutting speeds. The parameter of shear localization sensitivity is put forward to describe the influences of material mechanical properties on serrated chip formation. The results demonstrate that the effects of initial yield stress and thermal softening coefficient on chip shear localization are much more remarkable than the other constitutive parameters. For the material fracture parameters, the effects of initial fracture strain and exponential factor of stress state on chip shear localization are more much prominent. This paper provides guidance for controlling chip formation through the adjustment of material mechanical properties and the selection of appropriate cutting parameters.

Influences of Cutting Speed and Material Mechanical Properties on Chip Deformation and Fracture during High-Speed Cutting of Inconel 718.

Science.gov (United States)

Wang, Bing; Liu, Zhanqiang; Hou, Xin; Zhao, Jinfu

2018-03-21

The paper aims to investigate the influences of material constitutive and fracture parameters in addition to cutting speed on chip formation during high-speed cutting of Inconel 718. Finite element analyses for chip formation are conducted with Johnson-Cook constitutive and fracture models. Meanwhile, experiments of high-speed orthogonal cutting are performed to verify the simulation results with cutting speeds ranging from 50 m/min to 7000 m/min. The research indicates that the chip morphology transforms from serrated to fragmented at the cutting speed of 7000 m/min due to embrittlement of the workpiece material under ultra-high cutting speeds. The parameter of shear localization sensitivity is put forward to describe the influences of material mechanical properties on serrated chip formation. The results demonstrate that the effects of initial yield stress and thermal softening coefficient on chip shear localization are much more remarkable than the other constitutive parameters. For the material fracture parameters, the effects of initial fracture strain and exponential factor of stress state on chip shear localization are more much prominent. This paper provides guidance for controlling chip formation through the adjustment of material mechanical properties and the selection of appropriate cutting parameters.

A ductile fracture criterion with Zener-Hollomon parameter of pure molybdenum sheet in thermal forming

Directory of Open Access Journals (Sweden)

Wang Chu

2015-01-01

Full Text Available Formability of pure molybdenum in thermal forming process has been greatly improved, but it is still hard to avoid the generation of rupture and other quality defects. In this paper, a ductile fracture criterion of pure molybdenum sheet in thermal forming was established by considering the plastic deformation capacity of material and stress states, which can be used to describe fracture behaviour and critical rupture prediction of pure molybdenum sheet during hot forming process. Based on the isothermal uniaxial tensile tests which performed at 993 to 1143 K with strain rate range from 0.0005 to 0.2 s−1, the material parameters are calculated by the combination method of experiment with FEsimulation. Based on the observation, new fracture criteria can be expressed as a function of Zener-Hollomon parameter. The critical fracture value that calculated by Oyane-Sato criterion increases with increasing temperature and decreasing strain rate. The ductile fracture criterion with Zener-Hollomon parameter of pure molybdenum in thermal forming is proposed.

Separation of oily materials in radioactive waste waters by flotation. Determination of operation and control parameters

International Nuclear Information System (INIS)

Ortiz O, H.B.; Flores E, R.M.

2003-01-01

In this work the determination of the operation and control parameters (air/solids ratio G/S, retention time Θ, pressure P and de pressurized volume of mixed air-water V), of the flotation system used in the treatment of oleaginous residual water (polluted mainly with 60 Co) coming from the decontamination process of worn out oils, using as response parameters the concentration of oleaginous material and the residual turbidity. The obtained results allowed to observe the dependence of G/S with the pressure and volume of air-water given. At the same time it was settled down that the set of operation conditions that offers the greater separation percentage of G As and turbidity in the smallest time, they are those obtained by V 2 = 0.0012 m 3 and P 2 = 620 kPa, (G/S = 0.30 - 0.35, = 14-16 min) for what were employees as the ideal values of operation and control in the flotation system. As long as, the concentration of total Co is found under 1 mgL -1 . Finally, the selected flotation system showed high separation levels of 60 Co, whose specific activity are below of 0.007 BqmL -1 . (Author)

Design parameters of Tokamak-7 system

International Nuclear Information System (INIS)

Ivanov, D.P.; Keilin, V.E.; Klimenko, E.Yu.; Strelkov, V.S.

Superconducting windings for the main magnetic field of Tokamak-7 are discussed. The parameters of this facility are based on the use of commercially available superconducting materials for fields up to 80 kOe. Experimental parameters are described. (U.S.)

Study on the Reflection Spectra of One Dimensional Plasma Photonic Crystals Having Exponentially Graded Materials

International Nuclear Information System (INIS)

Prasad, S.; Singh, Vivek; Singh, A. K.

2013-01-01

The transfer matrix method is used to study the effect of the permittivity profile on the reflectivity of a one dimensional plasma photonic crystal having exponentially graded material. The analysis shows that the proposed structure works as a perfect mirror within a certain frequency range. These frequency ranges can be completely controlled by the permittivity profile of a graded dielectric layer. As expected we observed that these frequency ranges are also controlled by plasma parameters. (plasma technology)

Oxidation and creep behaviour of dense silicon nitride materials with different compositions

International Nuclear Information System (INIS)

Ernstberger, U.

1985-09-01

The study was intended to yield information on the oxidation and creep behaviour of Si 3 N 4 materials of different composition and microstructure, and produced by different processes. The experiments carried out in a vast temperature and load range showed that the chemical grain boundary composition is the key parameter affecting the materials' high-temperature properties. Significant correlations could be established between oxidation and creep behaviour on the one hand, and between microstructure and the behaviour on the other. (orig./IHOE) [de

Optimizing experimental parameters for the projection requirement in HAADF-STEM tomography

International Nuclear Information System (INIS)

Aveyard, R.; Zhong, Z.; Batenburg, K.J.; Rieger, B.

2017-01-01

Highlights: • The extent to which HAADF-STEM meets the projection requirement has been studied. • Multislice simulations used to model beam propagation and study signal linearity. • Propagation in crystalline and amorphous materials considered. • Optimal experimental set-up for the projection requirement is discussed. - Abstract: Tomographic reconstruction algorithms offer a means by which a tilt-series of transmission images can be combined to yield a three dimensional model of the specimen. Conventional reconstruction algorithms assume that the measured signal is a linear projection of some property, typically the density, of the material. Here we report the use of multislice simulations to investigate the extent to which this assumption is met in HAADF-STEM imaging. The use of simulations allows for a systematic survey of a range of materials and microscope parameters to inform optimal experimental design. Using this approach it is demonstrated that the imaging of amorphous materials is in good agreement with the projection assumption in most cases. Images of crystalline specimens taken along zone-axes are found to be poorly suited for conventional linear reconstruction algorithms due to channelling effects which produce enhanced intensities compared with off-axis images, and poor compliance with the projection requirement. Off-axis images are found to be suitable for reconstruction, though they do not strictly meet the linearity requirement in most cases. It is demonstrated that microscope parameters can be selected to yield improved compliance with the projection requirement.

Optimizing experimental parameters for the projection requirement in HAADF-STEM tomography

Energy Technology Data Exchange (ETDEWEB)

Aveyard, R., E-mail: r.a.aveyard@tudelft.nl [Department of Imaging Physics, Delft University of Technology, 2628CJ Delft (Netherlands); Zhong, Z.; Batenburg, K.J. [Centrum Wiskunde and Informatica, Science Park 123, NL-1098 XG Amsterdam (Netherlands); Rieger, B., E-mail: b.rieger@tudelft.nl [Department of Imaging Physics, Delft University of Technology, 2628CJ Delft (Netherlands)

2017-06-15

Highlights: • The extent to which HAADF-STEM meets the projection requirement has been studied. • Multislice simulations used to model beam propagation and study signal linearity. • Propagation in crystalline and amorphous materials considered. • Optimal experimental set-up for the projection requirement is discussed. - Abstract: Tomographic reconstruction algorithms offer a means by which a tilt-series of transmission images can be combined to yield a three dimensional model of the specimen. Conventional reconstruction algorithms assume that the measured signal is a linear projection of some property, typically the density, of the material. Here we report the use of multislice simulations to investigate the extent to which this assumption is met in HAADF-STEM imaging. The use of simulations allows for a systematic survey of a range of materials and microscope parameters to inform optimal experimental design. Using this approach it is demonstrated that the imaging of amorphous materials is in good agreement with the projection assumption in most cases. Images of crystalline specimens taken along zone-axes are found to be poorly suited for conventional linear reconstruction algorithms due to channelling effects which produce enhanced intensities compared with off-axis images, and poor compliance with the projection requirement. Off-axis images are found to be suitable for reconstruction, though they do not strictly meet the linearity requirement in most cases. It is demonstrated that microscope parameters can be selected to yield improved compliance with the projection requirement.

Data uncertainties in material flow analysis: Municipal solid waste management system in Maputo City, Mozambique.

Science.gov (United States)

Dos Muchangos, Leticia Sarmento; Tokai, Akihiro; Hanashima, Atsuko

2017-01-01

Material flow analysis can effectively trace and quantify the flows and stocks of materials such as solid wastes in urban environments. However, the integrity of material flow analysis results is compromised by data uncertainties, an occurrence that is particularly acute in low-and-middle-income study contexts. This article investigates the uncertainties in the input data and their effects in a material flow analysis study of municipal solid waste management in Maputo City, the capital of Mozambique. The analysis is based on data collected in 2007 and 2014. Initially, the uncertainties and their ranges were identified by the data classification model of Hedbrant and Sörme, followed by the application of sensitivity analysis. The average lower and upper bounds were 29% and 71%, respectively, in 2007, increasing to 41% and 96%, respectively, in 2014. This indicates higher data quality in 2007 than in 2014. Results also show that not only data are partially missing from the established flows such as waste generation to final disposal, but also that they are limited and inconsistent in emerging flows and processes such as waste generation to material recovery (hence the wider variation in the 2014 parameters). The sensitivity analysis further clarified the most influencing parameter and the degree of influence of each parameter on the waste flows and the interrelations among the parameters. The findings highlight the need for an integrated municipal solid waste management approach to avoid transferring or worsening the negative impacts among the parameters and flows.

Materials for high vacuum technology, an overview

CERN Document Server

Sgobba, Stefano

2007-01-01

In modern accelerators stringent requirements are placed on materials of vacuum systems. Their physical and mechanical properties, machinability, weldability or brazeability are key parameters. Adequate strength, ductility, magnetic properties at room as well as low temperatures are important factors for vacuum systems of accelerators working at cryogenic temperatures, such as the Large Hadron Collider (LHC) under construction at CERN. In addition, baking or activation of Non-Evaporable Getters (NEG) at high temperatures impose specific choices of material grades of suitable tensile and creep properties in a large temperature range. Today, stainless steels are the dominant materials of vacuum constructions. Their metallurgy is extensively treated. The reasons for specific requirements in terms of metallurgical processes are detailed, in view of obtaining adequate purity, inclusion cleanliness, and fineness of the microstructure. In many cases these requirements are crucial to guarantee the final leak tightnes...

Fluoride salts as phase change materials for thermal energy storage in the temperature range 1000-1400 K

Science.gov (United States)

Misra, Ajay K.

1988-01-01

Eutectic compositions and congruently melting intermediate compounds in binary and ternary fluoride salt systems were characterized for potential use as latent heat of fusion phase change materials to store thermal energy in the temperature range 1000-1400 K. The melting points and eutectic compositions for many systems with published phase diagrams were experimentally verified and new eutectic compositions having melting points between 1000 and 1400 K were identified. Heats of fusion of several binary and ternary eutectics and congruently melting compounds were experimentally measured by differential scanning calorimetry. For a few systems in which heats of mixing in the melts have been measured, heats of fusion of the eutectics were calculated from thermodynamic considerations and good agreement was obtained between the measured and calculated values. Several combinations of salts with high heats of fusion per unit mass (greater than 0.7 kJ/g) have been identified for possible use as phase change materials in advanced solar dynamic space power applications.

High-Strain-Rate Material Behavior and Adiabatic Material Instability in Impact of Micron-Scale Al-6061 Particles

Science.gov (United States)

Chen, Qiyong; Alizadeh, Arash; Xie, Wanting; Wang, Xuemei; Champagne, Victor; Gouldstone, Andrew; Lee, Jae-Hwang; Müftü, Sinan

2018-04-01

Impact of spherical particles onto a flat sapphire surface was investigated in 50-950 m/s impact speed range experimentally and theoretically. Material parameters of the bilinear Johnson-Cook model were determined based on comparison of deformed particle shapes from experiment and simulation. Effects of high-strain-rate plastic flow, heat generation due to plasticity, material damage, interfacial friction and heat transfer were modeled. Four distinct regions were identified inside the particle by analyzing temporal variation of material flow. A relatively small volume of material near the impact zone becomes unstable due to plasticity-induced heating, accompanied by severe drop in the flow stress for impact velocity that exceeds 500 m/s. Outside of this region, flow stress is reduced due to temperature effects without the instability. Load carrying capacity of the material degrades and the material expands horizontally leading to jetting. The increase in overall plastic and frictional dissipation with impact velocity was found to be inherently lower than the increase in the kinetic energy at high speeds, leading to the instability. This work introduces a novel method to characterize HSR (109 s-1) material properties and also explains coupling between HSR material behavior and mechanics that lead to extreme deformation.

Geopolymer resin materials, geopolymer materials, and materials produced thereby

Energy Technology Data Exchange (ETDEWEB)

Seo, Dong-Kyun; Medpelli, Dinesh; Ladd, Danielle; Mesgar, Milad

2018-01-09

A product formed from a first material including a geopolymer resin material, a geopolymer material, or a combination thereof by contacting the first material with a fluid and removing at least some of the fluid to yield a product. The first material may be formed by heating and/or aging an initial geopolymer resin material to yield the first material before contacting the first material with the fluid. In some cases, contacting the first material with the fluid breaks up or disintegrates the first material (e.g., in response to contact with the fluid and in the absence of external mechanical stress), thereby forming particles having an external dimension in a range between 1 nm and 2 cm.

Lattice parameters guide superconductivity in iron-arsenides

Science.gov (United States)

Konzen, Lance M. N.; Sefat, Athena S.

2017-03-01

The discovery of superconducting materials has led to their use in technological marvels such as magnetic-field sensors in MRI machines, powerful research magnets, short transmission cables, and high-speed trains. Despite such applications, the uses of superconductors are not widespread because they function much below room-temperature, hence the costly cooling. Since the discovery of Cu- and Fe-based high-temperature superconductors (HTS), much intense effort has tried to explain and understand the superconducting phenomenon. While no exact explanations are given, several trends are reported in relation to the materials basis in magnetism and spin excitations. In fact, most HTS have antiferromagnetic undoped ‘parent’ materials that undergo a superconducting transition upon small chemical substitutions in them. As it is currently unclear which ‘dopants’ can favor superconductivity, this manuscript investigates crystal structure changes upon chemical substitutions, to find clues in lattice parameters for the superconducting occurrence. We review the chemical substitution effects on the crystal lattice of iron-arsenide-based crystals (2008 to present). We note that (a) HTS compounds have nearly tetragonal structures with a-lattice parameter close to 4 Å, and (b) superconductivity can depend strongly on the c-lattice parameter changes with chemical substitution. For example, a decrease in c-lattice parameter is required to induce ‘in-plane’ superconductivity. The review of lattice parameter trends in iron-arsenides presented here should guide synthesis of new materials and provoke theoretical input, giving clues for HTS.

Generating three-parameter sensor

Directory of Open Access Journals (Sweden)

Filinyuk M. A.

2014-08-01

Full Text Available Generating sensors provide the possibility of getting remote information and its easy conversion into digital form. Typically, these are one-parameter sensors formed by combination of a primary transmitter (PT and a sine wave generator. Two-parameter sensors are not widely used as their implementation causes a problem with ambiguity output when measuring the PT. Nevertheless, the problem of creating miniature, thrifty multi-parameter RF sensors for different branches of science and industry remains relevant. Considering ways of designing RF sensors, we study the possibility of constructing a three-parameter microwave radio frequency range sensor, which is based on a two-stage three-parameter generalized immitance convertor (GIC. Resistive, inductive and capacitive PT are used as sensing elements. A mathematical model of the sensor, which describes the relation of the sensor parameters to the parameters of GIC and PT was developed. The basic parameters of the sensor, its transfer function and sensitivity were studied. It is shown that the maximum value of the power generated signal will be observed at a frequency of 175 MHz, and the frequency ranges depending on the parameters of the PT will be different. Research results and adequacy of the mathematical model were verified by the experiment. Error of the calculated dependences of the lasing frequency on PT parameters change, compared with the experimental data does not exceed 2 %. The relative sensitivity of the sensor based on two-stage GIC showed that for the resistive channel it is about 1.88, for the capacitive channel –1,54 and for the inductive channel –11,5. Thus, it becomes possible to increase the sensor sensitivity compared with the sensitivity of the PT almost 1,2—2 times, and by using the two stage GIC a multifunctional sensor is provided.

Measurement of the magnetic material properties for ferrite-loaded cavities

Directory of Open Access Journals (Sweden)

Klaus Klopfer

2015-01-01

Full Text Available Measurements of the magnetic characteristics of the Ferroxcube 8C12m ferrite material in the parameter range where the GSI heavy-ion synchrotron SIS 18 cavity resonator is operated are presented. At first, the permeability is determined as a function of frequency and bias magnetic field strength for low radio-frequency power levels. For this purpose, both reflection and transmission measurements are carried out in a test setup with two toroids. The values for the real and imaginary part obtained from the data analysis of both approaches are fully in agreement with each other, albeit the range of application of the latter setup is limited to moderate frequencies due to parasitic resonances. An empirical analytical expression is formulated which approximates the complex permeability reasonably well in the whole investigated bias and frequency range. Moreover, the B-H curve is recorded for a reduced bias current range of the cavity. The gained material characteristics are well suited for numerical eigenmode simulations for the GSI SIS 18 cavity.

Recovering Parameters of Johnson's SB Distribution

Science.gov (United States)

Bernard R. Parresol

2003-01-01

A new parameter recovery model for Johnson's SB distribution is developed. This latest alternative approach permits recovery of the range and both shape parameters. Previous models recovered only the two shape parameters. Also, a simple procedure for estimating the distribution minimum from sample values is presented. The new methodology...

Dielectric function in the spectral range (0.5–8.5)eV of an (AlxGa1−x)2O3 thin film with continuous composition spread

International Nuclear Information System (INIS)

Schmidt-Grund, R.; Kranert, C.; Wenckstern, H. von; Zviagin, V.; Lorenz, M.; Grundmann, M.

2015-01-01

We determined the dielectric function of the alloy system (Al x Ga 1−x ) 2 O 3 by spectroscopic ellipsometry in the wide spectral range from 0.5 eV to 8.5 eV and for Al contents ranging from x = 0.11 to x = 0.55. For the composition range x < 0.4, we observe single phase material in the β-modification and for larger Al content also the occurrence of γ-(Al,Ga) 2 O 3 . We derived spectra of the refractive index and the absorption coefficient as well as energy parameters of electronic band-band transitions by model analysis of the dielectric function. The dependence of the dielectric functions lineshape and the energy parameters on x is highly continuous, reflecting theoretical expectations. The data presented here provide a basis for a deeper understanding of the electronic properties of this material system and may be useful for device engineering

Geopolymer resin materials, geopolymer materials, and materials produced thereby

Science.gov (United States)

Seo, Dong-Kyun; Medpelli, Dinesh; Ladd, Danielle; Mesgar, Milad

2016-03-29

A product formed from a first material including a geopolymer resin material, a geopolymer resin, or a combination thereof by contacting the first material with a fluid and removing at least some of the fluid to yield a product. The first material may be formed by heating and/or aging an initial geopolymer resin material to yield the first material before contacting the first material with the fluid. In some cases, contacting the first material with the fluid breaks up or disintegrates the first material (e.g., in response to contact with the fluid and in the absence of external mechanical stress), thereby forming particles having an external dimension in a range between 1 nm and 2 cm.

Bayesian Regression of Thermodynamic Models of Redox Active Materials

Energy Technology Data Exchange (ETDEWEB)

Johnston, Katherine [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-09-01

Finding a suitable functional redox material is a critical challenge to achieving scalable, economically viable technologies for storing concentrated solar energy in the form of a defected oxide. Demonstrating e ectiveness for thermal storage or solar fuel is largely accomplished by using a thermodynamic model derived from experimental data. The purpose of this project is to test the accuracy of our regression model on representative data sets. Determining the accuracy of the model includes parameter tting the model to the data, comparing the model using di erent numbers of param- eters, and analyzing the entropy and enthalpy calculated from the model. Three data sets were considered in this project: two demonstrating materials for solar fuels by wa- ter splitting and the other of a material for thermal storage. Using Bayesian Inference and Markov Chain Monte Carlo (MCMC), parameter estimation was preformed on the three data sets. Good results were achieved, except some there was some deviations on the edges of the data input ranges. The evidence values were then calculated in a variety of ways and used to compare models with di erent number of parameters. It was believed that at least one of the parameters was unnecessary and comparing evidence values demonstrated that the parameter was need on one data set and not signi cantly helpful on another. The entropy was calculated by taking the derivative in one variable and integrating over another. and its uncertainty was also calculated by evaluating the entropy over multiple MCMC samples. Afterwards, all the parts were written up as a tutorial for the Uncertainty Quanti cation Toolkit (UQTk).

Egg quality and blood parameters of “Bianca di Saluzzo” and Isa Brown hens kept under free range conditions

Directory of Open Access Journals (Sweden)

Luca Doglione

2010-01-01

Full Text Available Egg quality traits and some blood parameters of Bianca di Saluzzo hen (BSh were compared to Isa Brown hen (IBh. Birds were reared in free range conditions. Weightofthewholeegg Weight of the whole egg was higher (P≤0.01 for IBh, due to its higher amount of albumen (P≤0.01 whereas BSh egg showed the highest weight and relative percentage of yolk (PP≤0.01. IBh and BSh egg chemical composition was similar.Totalredcellsdidnotshowstatisticaldifferencesbetweengroups,whiletotalleucocytes Total red cells did not show statistical differences between groups, while total leucocytes were lower (P≤0.05 forBShhens. Heterophyl/Lymphocyte(H/L ratioof BShwaslower (P for BSh hens. Heterophyl/Lymphocyte(H/L ratioof BShwaslower (P . Heterophyl/Lymphocyte(H/L ratioof BShwaslower (P Heterophyl/Lymphocyte (H/L ratio of BSh was lower (P (PP≤0.01 than IBh(0.33 IBh (0.33 (0.33 vs. 0.82.IBh 0.82. IBh IBh α-1 acid glycoprotein (AGPmeanconcentrationswereaffectedbytime: (AGP mean concentrations were affected by time: the values registered after 15 d (T1 and 2 months (T2 of observation were similar (345±132 and 279±58 μg/mlrespectively,whileAGPvalueregisteredafter4months(T3weresignificantlyhigher μg/ml respectively,whileAGPvalueregisteredafter4months(T3weresignificantlyhigher , while AGP value registered after 4 months (T3 were significantly higher (700±487 μg/ml;BShdidnotdisplayanyAGPstatisticalvariationovertime.IBhalbuminmeancon- μg/ml; BShdidnotdisplayanyAGPstatisticalvariationovertime.IBhalbuminmeancon- BSh did not display any AGP statistical variation over time. IBh albumin mean con- centration (1.62 g/dL was statistically lower than BSh values (1.89 g/dL; in both groups no effect of time of sampling was recorded. Acutephaseprotein(APPvaluesofBShsuggestedamoreadaptive Acute phase protein (APPvaluesofBShsuggestedamoreadaptive (APP values of BSh suggested a more adaptive attitude to free range conditions and appeared more constant over time. The present

Macroscopically constrained Wang-Landau method for systems with multiple order parameters and its application to drawing complex phase diagrams

Science.gov (United States)

Chan, C. H.; Brown, G.; Rikvold, P. A.

2017-05-01

A generalized approach to Wang-Landau simulations, macroscopically constrained Wang-Landau, is proposed to simulate the density of states of a system with multiple macroscopic order parameters. The method breaks a multidimensional random-walk process in phase space into many separate, one-dimensional random-walk processes in well-defined subspaces. Each of these random walks is constrained to a different set of values of the macroscopic order parameters. When the multivariable density of states is obtained for one set of values of fieldlike model parameters, the density of states for any other values of these parameters can be obtained by a simple transformation of the total system energy. All thermodynamic quantities of the system can then be rapidly calculated at any point in the phase diagram. We demonstrate how to use the multivariable density of states to draw the phase diagram, as well as order-parameter probability distributions at specific phase points, for a model spin-crossover material: an antiferromagnetic Ising model with ferromagnetic long-range interactions. The fieldlike parameters in this model are an effective magnetic field and the strength of the long-range interaction.

Calibration of discrete element model parameters: soybeans

Science.gov (United States)

Ghodki, Bhupendra M.; Patel, Manish; Namdeo, Rohit; Carpenter, Gopal

2018-05-01

Discrete element method (DEM) simulations are broadly used to get an insight of flow characteristics of granular materials in complex particulate systems. DEM input parameters for a model are the critical prerequisite for an efficient simulation. Thus, the present investigation aims to determine DEM input parameters for Hertz-Mindlin model using soybeans as a granular material. To achieve this aim, widely acceptable calibration approach was used having standard box-type apparatus. Further, qualitative and quantitative findings such as particle profile, height of kernels retaining the acrylic wall, and angle of repose of experiments and numerical simulations were compared to get the parameters. The calibrated set of DEM input parameters includes the following (a) material properties: particle geometric mean diameter (6.24 mm); spherical shape; particle density (1220 kg m^{-3} ), and (b) interaction parameters such as particle-particle: coefficient of restitution (0.17); coefficient of static friction (0.26); coefficient of rolling friction (0.08), and particle-wall: coefficient of restitution (0.35); coefficient of static friction (0.30); coefficient of rolling friction (0.08). The results may adequately be used to simulate particle scale mechanics (grain commingling, flow/motion, forces, etc) of soybeans in post-harvest machinery and devices.

In vivo spectroscopy of healthy skin and pathology in terahertz frequency range

International Nuclear Information System (INIS)

Zaytsev, Kirill I; Gavdush, Arseniy A; Chernomyrdin, Nikita V; Karasik, Valeriy E; Yurchenko, Stanislav O; Kudrin, Konstantin G; Reshetov, Igor V

2015-01-01

Biomedical applications of terahertz (THz) technology and, in particular, THz pulsed spectroscopy have attracted considerable interest in the scientific community. A lot of papers have been dedicated to studying the ability for human disease diagnosis, including the diagnosis of human skin cancers. In this paper we have studied the THz material parameters and THz dielectric properties of human skin and pathology in vivo, and THz pulsed spectroscopy has been utilized for this purpose. We have found a contrast between material parameters of basal cell carcinoma and healthy skin, and we have also compared the THz material parameters of dysplastic and non-dysplastic pigmentary nevi in order to study the ability for early melanoma diagnosis. Significant differences between the THz material parameters of healthy skin and pathology have been detected, thus, THz pulsed spectroscopy promises to be become an effective tool for non-invasive diagnosis of skin neoplasms

Readability of pediatric health materials for preventive dental care

Directory of Open Access Journals (Sweden)

Riedy Christine A

2006-11-01

Full Text Available Abstract Background This study examined the content and general readability of pediatric oral health education materials for parents of young children. Methods Twenty-seven pediatric oral health pamphlets or brochures from commercial, government, industry, and private nonprofit sources were analyzed for general readability ("usability" according to several parameters: readability, (Flesch-Kincaid grade level, Flesch Reading Ease, and SMOG grade level; thoroughness, (inclusion of topics important to young childrens' oral health; textual framework (frequency of complex phrases, use of pictures, diagrams, and bulleted text within materials; and terminology (frequency of difficult words and dental jargon. Results Readability of the written texts ranged from 2nd to 9th grade. The average Flesch-Kincaid grade level for government publications was equivalent to a grade 4 reading level (4.73, range, 2.4 – 6.6; F-K grade levels for commercial publications averaged 8.1 (range, 6.9 – 8.9; and industry published materials read at an average Flesch-Kincaid grade level of 7.4 (range, 4.7 – 9.3. SMOG readability analysis, based on a count of polysyllabic words, consistently rated materials 2 to 3 grade levels higher than did the Flesch-Kincaid analysis. Government sources were significantly lower compared to commercial and industry sources for Flesch-Kincaid grade level and SMOG readability analysis. Content analysis found materials from commercial and industry sources more complex than government-sponsored publications, whereas commercial sources were more thorough in coverage of pediatric oral health topics. Different materials frequently contained conflicting information. Conclusion Pediatric oral health care materials are readily available, yet their quality and readability vary widely. In general, government publications are more readable than their commercial and industry counterparts. The criteria for usability and results of the analyses

Fusion reactor materials

Energy Technology Data Exchange (ETDEWEB)

none,

1989-01-01

This paper discuses the following topics on fusion reactor materials: irradiation, facilities, test matrices, and experimental methods; dosimetry, damage parameters, and activation calculations; materials engineering and design requirements; fundamental mechanical behavior; radiation effects; development of structural alloys; solid breeding materials; and ceramics.

Fusion reactor materials

International Nuclear Information System (INIS)

1989-01-01

This paper discuses the following topics on fusion reactor materials: irradiation, facilities, test matrices, and experimental methods; dosimetry, damage parameters, and activation calculations; materials engineering and design requirements; fundamental mechanical behavior; radiation effects; development of structural alloys; solid breeding materials; and ceramics

Uncertainty estimation in nuclear material weighing

Energy Technology Data Exchange (ETDEWEB)

Thaure, Bernard [Institut de Radioprotection et de Surete Nucleaire, Fontenay aux Roses, (France)

2011-12-15

The assessment of nuclear material quantities located in nuclear plants requires knowledge of additions and subtractions of amounts of different types of materials. Most generally, the quantity of nuclear material held is deduced from 3 parameters: a mass (or a volume of product); a concentration of nuclear material in the product considered; and an isotopic composition. Global uncertainties associated with nuclear material quantities depend upon the confidence level of results obtained in the measurement of every different parameter. Uncertainties are generally estimated by considering five influencing parameters (ISHIKAWA's rule): the material itself; the measurement system; the applied method; the environmental conditions; and the operator. A good practice guide, to be used to deal with weighing errors and problems encountered, is presented in the paper.

Thermal parameter identification for non-Fourier heat transfer from molecular dynamics

Science.gov (United States)

Singh, Amit; Tadmor, Ellad B.

2015-10-01

Fourier's law leads to a diffusive model of heat transfer in which a thermal signal propagates infinitely fast and the only material parameter is the thermal conductivity. In micro- and nano-scale systems, non-Fourier effects involving coupled diffusion and wavelike propagation of heat can become important. An extension of Fourier's law to account for such effects leads to a Jeffreys-type model for heat transfer with two relaxation times. We propose a new Thermal Parameter Identification (TPI) method for obtaining the Jeffreys-type thermal parameters from molecular dynamics simulations. The TPI method makes use of a nonlinear regression-based approach for obtaining the coefficients in analytical expressions for cosine and sine-weighted averages of temperature and heat flux over the length of the system. The method is applied to argon nanobeams over a range of temperature and system sizes. The results for thermal conductivity are found to be in good agreement with standard Green-Kubo and direct method calculations. The TPI method is more efficient for systems with high diffusivity and has the advantage, that unlike the direct method, it is free from the influence of thermostats. In addition, the method provides the thermal relaxation times for argon. Using the determined parameters, the Jeffreys-type model is able to reproduce the molecular dynamics results for a short-duration heat pulse where wavelike propagation of heat is observed thereby confirming the existence of second sound in argon. An implementation of the TPI method in MATLAB is available as part of the online supplementary material.

Soil and geomorphological parameters to characterize natural environmental and human induced changes within the Guadarrama Range (Central Spain)

Science.gov (United States)

Schmid, Thomas; Inclán-Cuartas, Rosa M.; Santolaria-Canales, Edmundo; Saa, Antonio; Rodríguez-Rastrero, Manuel; Tanarro-Garcia, Luis M.; Luque, Esperanza; Pelayo, Marta; Ubeda, Jose; Tarquis, Ana; Diaz-Puente, Javier; De Marcos, Javier; Rodriguez-Alonso, Javier; Hernandez, Carlos; Palacios, David; Gallardo-Díaz, Juan; Fidel González-Rouco, J.

2016-04-01

to determine the physical and chemical soil properties. The parent material is gneiss andassociated deposits and, as a result, soils are acid. The soils have a low to medium organic matter content and are non-saline. They are moderately to well drained soils and have no or slight evidence of erosion. The soil within the high mountain area has clear evidence of frost heave that has a vertical displacement of the surface in the centimeter range. The stations within the lowland and mid mountain areas represent the most degraded sites as a result of the livestock keeping, whereas the high mountain area is mainly influenced by natural environmental conditions. These soil and geomorphological parameters will constitute a basis for site characterization in future studies regarding soil degradation; determining the interaction between soil, vegetation and atmosphere with respect to human induced activities (e.g. atmospheric contamination and effects of fires); determining the nitrogen and carbon cycles; and the influence of heavy metal contaminants in the soils.

Evaluating the parameters of reactor structure materials absorption by means of a new kind integral experiments

International Nuclear Information System (INIS)

Bemer, B.; Dittse, K.; Fehrrann, K.; Khyuttet', G.; Kumpf, G.; Lemann, E.

1984-01-01

Integral experiment of a new type is conducted for determination of the effective cross sections of structural material absorption in fast reactors. Its essence is that absorption cross sections are determined directly from the measured central coefficients of reactivities in the special fast inserting lattice SEG-4 with energy-independent neutron importance function. Parameters of the system, method of measurements, advantages of the method as compared with Ksub(infinity)=I method are described. The results of measurements for Fe, Cr, Ni, Mn, Mo and W are presented. Problems of mass dependence of the sample are discussed. Conclusion on universality of the suggested method is made on the basis of comparing the obtained results with data of calculations conducted by using different libraries of nuclear data

Investigation of tritium inventory and permeation behaviour in the liquid breeder blanket concept of Demo as a function of design and material parameters

International Nuclear Information System (INIS)

Tominetti, S.; Perujo, A.; Reiter, F.

1991-01-01

A numerical code has been used to estimate the time dependence of tritium inventory and of tritium transport into the coolant, into the first wall boxes and through the liquid breeder in the Pb-17Li blanket concept of DEMO. Several issues in both design and material parameters have been considered and the effect on inventory and permeation of coatings with low surface recombination coefficient and/or low diffusivity at various surfaces of the structural material has been studied. TiC has been chosen as reference material for these calculations and a general database on coating efficiency as a function of its properties has also been produced on the basis of TiC data

Weld nugget formation in resistance spot welding of new lightweight sandwich material

DEFF Research Database (Denmark)

Sagüés Tanco, J.; Nielsen, Chris Valentin; Chergui, Azeddine

2015-01-01

Weldability of a new lightweight sandwich material, LITECOR®, by resistance spot welding is analyzed by experiments and numerical simulations. The spot welding process is accommodated by a first pulse squeezing out the non-conductive polymer core of the sandwich material locally to allow metal......–metal contact. This is facilitated by the use of a shunt tool and is followed by a second pulse for the actual spot welding and nugget formation. A weldability lobe in the time-current space of the second pulse reveals a process window of acceptable size for automotive assembly lines. Weld growth curves...... with experimental results in the range of welding parameters leading to acceptable weld nugget sizes. The validated accuracy of the commercially available software proves the tool useful for assisting the choice of welding parameters....

Electron spin resonance for the detection of long-range spin nematic order

Science.gov (United States)

Furuya, Shunsuke C.; Momoi, Tsutomu

2018-03-01

Spin nematic phase is a quantum magnetic phase characterized by a quadrupolar order parameter. Since the quadrupole operators are directly coupled to neither the magnetic field nor the neutron, currently, it is an important issue to develop a method for detecting the long-range spin nematic order. In this paper, we propose that electron spin resonance (ESR) measurements enable us to detect the long-range spin nematic order. We show that the frequency of the paramagnetic resonance peak in the ESR spectrum is shifted by the ferroquadrupolar order parameter together with other quantities. The ferroquadrupolar order parameter is extractable from the angular dependence of the frequency shift. In contrast, the antiferroquadrupolar order parameter is usually invisible in the frequency shift. Instead, the long-range antiferroquadrupolar order yields a characteristic resonance peak in the ESR spectrum, which we call a magnon-pair resonance peak. This resonance corresponds to the excitation of the bound magnon pair at the wave vector k =0 . Reflecting the condensation of bound magnon pairs, the field dependence of the magnon-pair resonance frequency shows a singular upturn at the saturation field. Moreover, the intensity of the magnon-pair resonance peak shows a characteristic angular dependence and it vanishes when the magnetic field is parallel to one of the axes that diagonalize the weak anisotropic interactions. We confirm these general properties of the magnon-pair resonance peak in the spin nematic phase by studying an S =1 bilinear-biquadratic model on the square lattice in the linear flavor-wave approximation. In addition, we argue applications to the S =1/2 frustrated ferromagnets and also the S =1/2 orthogonal dimer spin system SrCu2(BO3)2, both of which are candidate materials of spin nematics. Our theory for the antiferroquadrupolar ordered phase is consistent with many features of the magnon-pair resonance peak experimentally observed in the low

Influence of the electromagnetic parameters on the surface wave attenuation in thin absorbing layers

Science.gov (United States)

Li, Yinrui; Li, Dongmeng; Wang, Xian; Nie, Yan; Gong, Rongzhou

2018-05-01

This paper describes the relationships between the surface wave attenuation properties and the electromagnetic parameters of radar absorbing materials (RAMs). In order to conveniently obtain the attenuation constant of TM surface waves over a wide frequency range, the simplified dispersion equations in thin absorbing materials were firstly deduced. The validity of the proposed method was proved by comparing with the classical dispersion equations. Subsequently, the attenuation constants were calculated separately for the absorbing layers with hypothetical relative permittivity and permeability. It is found that the surface wave attenuation properties can be strongly tuned by the permeability of RAM. Meanwhile, the permittivity should be appropriate so as to maintain high cutoff frequency. The present work provides specific methods and designs to improve the attenuation performances of radar absorbing materials.

Challenges in Materials Transformation Modeling for Polyolefins Industry

Science.gov (United States)

Lai, Shih-Yaw; Swogger, Kurt W.

2004-06-01

Unlike most published polymer processing and/or forming research, the transformation of polyolefins to fabricated articles often involves non-confined flow or so-called free surface flow (e.g. fiber spinning, blown films, and cast films) in which elongational flow takes place during a fabrication process. Obviously, the characterization and validation of extensional rheological parameters and their use to develop rheological constitutive models are the focus of polyolefins materials transformation research. Unfortunately, there are challenges that remain with limited validation for non-linear, non-isothermal constitutive models for polyolefins. Further complexity arises in the transformation of polyolefins in the elongational flow system as it involves stress-induced crystallization process. The complicated nature of elongational, non-linear rheology and non-isothermal crystallization kinetics make the development of numerical methods very challenging for the polyolefins materials forming modeling. From the product based company standpoint, the challenges of materials transformation research go beyond elongational rheology, crystallization kinetics and its numerical modeling. In order to make models useful for the polyolefin industry, it is critical to develop links between molecular parameters to both equipment and materials forming parameters. The recent advances in the constrained geometry catalysis and materials sciences understanding (INSITE technology and molecular design capability) has made industrial polyolefinic materials forming modeling more viable due to the fact that the molecular structure of the polymer can be well predicted and controlled during the polymerization. In this paper, we will discuss inter-relationship (models) among molecular parameters such as polymer molecular weight (Mw), molecular weight distribution (MWD), long chain branching (LCB), short chain branching (SCB or comonomer types and distribution) and their affects on shear and

Terahertz (THz) Optical Parameters of Three-Dimensional (3-D) Printing Materials

Science.gov (United States)

2017-03-01

Terahertz (THz), Submillimeter Wave, Imaging 15. NUMBER OF PAGES 16 16. PRICE CODE 17. SECURITY CLASSIFICATION OF REPORT UNCLASSIFIED 18...and imaging has become a topic of research as an optical technique to study these materials because THz radiation can penetrate many visibly opaque...2) Three materials, each tinted with two different colors, were measured. The materials were High Impact polystyrene (HIPS

Process Parameter Optimization of Extrusion-Based 3D Metal Printing Utilizing PW-LDPE-SA Binder System.

Science.gov (United States)

Ren, Luquan; Zhou, Xueli; Song, Zhengyi; Zhao, Che; Liu, Qingping; Xue, Jingze; Li, Xiujuan

2017-03-16

Recently, with a broadening range of available materials and alteration of feeding processes, several extrusion-based 3D printing processes for metal materials have been developed. An emerging process is applicable for the fabrication of metal parts into electronics and composites. In this paper, some critical parameters of extrusion-based 3D printing processes were optimized by a series of experiments with a melting extrusion printer. The raw materials were copper powder and a thermoplastic organic binder system and the system included paraffin wax, low density polyethylene, and stearic acid (PW-LDPE-SA). The homogeneity and rheological behaviour of the raw materials, the strength of the green samples, and the hardness of the sintered samples were investigated. Moreover, the printing and sintering parameters were optimized with an orthogonal design method. The influence factors in regard to the ultimate tensile strength of the green samples can be described as follows: infill degree > raster angle > layer thickness. As for the sintering process, the major factor on hardness is sintering temperature, followed by holding time and heating rate. The highest hardness of the sintered samples was very close to the average hardness of commercially pure copper material. Generally, the extrusion-based printing process for producing metal materials is a promising strategy because it has some advantages over traditional approaches for cost, efficiency, and simplicity.

Process Parameter Optimization of Extrusion-Based 3D Metal Printing Utilizing PW–LDPE–SA Binder System

Directory of Open Access Journals (Sweden)

Luquan Ren

2017-03-01

Full Text Available Recently, with a broadening range of available materials and alteration of feeding processes, several extrusion-based 3D printing processes for metal materials have been developed. An emerging process is applicable for the fabrication of metal parts into electronics and composites. In this paper, some critical parameters of extrusion-based 3D printing processes were optimized by a series of experiments with a melting extrusion printer. The raw materials were copper powder and a thermoplastic organic binder system and the system included paraffin wax, low density polyethylene, and stearic acid (PW–LDPE–SA. The homogeneity and rheological behaviour of the raw materials, the strength of the green samples, and the hardness of the sintered samples were investigated. Moreover, the printing and sintering parameters were optimized with an orthogonal design method. The influence factors in regard to the ultimate tensile strength of the green samples can be described as follows: infill degree > raster angle > layer thickness. As for the sintering process, the major factor on hardness is sintering temperature, followed by holding time and heating rate. The highest hardness of the sintered samples was very close to the average hardness of commercially pure copper material. Generally, the extrusion-based printing process for producing metal materials is a promising strategy because it has some advantages over traditional approaches for cost, efficiency, and simplicity.

Process Parameter Optimization of Extrusion-Based 3D Metal Printing Utilizing PW–LDPE–SA Binder System

Science.gov (United States)

Ren, Luquan; Zhou, Xueli; Song, Zhengyi; Zhao, Che; Liu, Qingping; Xue, Jingze; Li, Xiujuan

2017-01-01

Recently, with a broadening range of available materials and alteration of feeding processes, several extrusion-based 3D printing processes for metal materials have been developed. An emerging process is applicable for the fabrication of metal parts into electronics and composites. In this paper, some critical parameters of extrusion-based 3D printing processes were optimized by a series of experiments with a melting extrusion printer. The raw materials were copper powder and a thermoplastic organic binder system and the system included paraffin wax, low density polyethylene, and stearic acid (PW–LDPE–SA). The homogeneity and rheological behaviour of the raw materials, the strength of the green samples, and the hardness of the sintered samples were investigated. Moreover, the printing and sintering parameters were optimized with an orthogonal design method. The influence factors in regard to the ultimate tensile strength of the green samples can be described as follows: infill degree > raster angle > layer thickness. As for the sintering process, the major factor on hardness is sintering temperature, followed by holding time and heating rate. The highest hardness of the sintered samples was very close to the average hardness of commercially pure copper material. Generally, the extrusion-based printing process for producing metal materials is a promising strategy because it has some advantages over traditional approaches for cost, efficiency, and simplicity. PMID:28772665

The features of radiation induced lung fibrosis related with dosimetric parameters

International Nuclear Information System (INIS)

Oh, Young-Taek; Noh, O Kyu; Jang, Hyunsoo; Chun, Mison; Park, Kyung Joo; Park, Kwang Joo; Kim, Mi-Hwa; Park, Hae-Jin

2012-01-01

Background and purpose: Radiation induced lung fibrosis (RILF) is a major complication after lung irradiation and is very important for long term quality of life and could result in fatal respiratory insufficiency. However, there has been little information on dosimetric parameters for radiotherapy planning in the aspect of RILF. The features of RILF related with dosimetric parameters were evaluated. Methods and materials: Forty-eight patients with non-small cell lung carcinoma who underwent post-operative radiation therapy (PORT) without adjuvant chemotherapy were analyzed. The degree of lung fibrosis was estimated by fibrosis volume and the dosimetric parameters were calculated from the plan of 3-dimensional conformal radiotherapy. Results: The fibrosis volume and V-dose as dosimetric parameters showed significant correlation and the correlation coefficient ranged from 0.602 to 0.683 (P < 0.01). The degree of the correlation line was steeper as the dose increase and threshold dose was not found. Mean lung dose (MLD) showed strong correlation with fibrosis volume (correlation coefficient = 0.726, P < 0.01). Conclusions: The fibrosis volume is continuously increased with V-dose as the reference dose increases. MLD is useful as a single parameter for comparing rival plans in the aspect of RILF.

Rating anthropometric parameters of children with polyarticular hypermobility

Directory of Open Access Journals (Sweden)

Mario Cardinali

2018-03-01

Full Text Available Introduction: Polyarticular hypermobility manifests in an increased range of motion in the joints compared to standards that include gender and age. It is given that it occurs even in 30% of children. It can lead to many biomechanical disorders and injuries. Science, which describes the measurement of the different body parameters such as height, body weight or fat content in the body is anthropometry and it was used to characterize the child diagnosed with arthritis polyarticular hypermobility. Material and Methods: The study was conducted on the group of 35 children aged 6 to 11 years old with diagnosed polyarticular hypermobility. The control group were randomly selected children in the same age from the same school without diagnosed polyarticular hypermobility. Anthropometric parameters of all children were measured according to accepted methods. The children were tested for body weight, height, body mass index, WHR index and their skinfolds were measured by skinfolds calipers. Objective: The aim of this study was to evaluate the anthropometric parameters of children with diagnosed polyarticular hypermobility and to compare these results to their contemporaries with no identified polyarticular hypermobility. Results: All the examined parameters (height, body weight, BMI, WHR, skinfolds measurement in the two groups were on very similar levels, there were no statistically significant differences (BMI p = 0.3435, WHR p = 0.806. Conclusions: There is no significant difference between the study group and the control group in the examined anthropometric parameters (height, body weight and BMI. Children with diagnosed polyarticular hypermobility in terms of weight and height do not stand out from their peers.

Status of the solid breeder materials database

International Nuclear Information System (INIS)

Billone, M.C.; Dienst, W.; Lorenzetto, P.; Noda, K.; Roux, N.

1995-01-01

The databases for solid breeder ceramics (Li 2 O, Li 4 SiO 4 , Li 2 ZrO 3 , and LiAlO 2 ) and beryllium multiplier material were critically reviewed and evaluated as part of the ITER/CDA design effort (1988-1990). The results have been documented in a detailed technical report. Emphasis was placed on the physical, thermal, mechanical, chemical stability/compatibility, tritium retention/release, and radiation stability properties which are needed to assess the performance of these materials in a fusion reactor environment. Materials properties correlations were selected for use in design analysis, and ranges for input parameters (e.g., temperature, porosity, etc.) were established. Also, areas for future research and development in blanket materials technology were highlighted and prioritized. For Li 2 O, the most significant increase in the database has come in the area of tritium retention as a function of operating temperature and purge flow composition. The database for postirradiation inventory from purged in-reactor samples has increased from four points to 20 points. These new data have allowed an improvement in understanding and modeling, as well as better interpretation of the results of laboratory annealing studies on unirradiated and irradiated material. In the case of Li 2 ZrO 3 , relatively little data were available on the sensitivity of the mechanical properties of this ternary ceramic to microstructure and moisture content. The increase in the database for this material has allowed not only better characterization of its properties, but also optimization of fabrication parameters to improve its performance. Some additional data are also available for the other two ternary ceramics to aid in the characterization of their performance. In particular, the thermal performance of these materials, as well as beryllium, in packed-bed form has been measured and characterized

Material parameters from frequency dispersion simulation of floating gate memory with Ge nanocrystals in HfO2

Science.gov (United States)

Palade, C.; Lepadatu, A. M.; Slav, A.; Lazanu, S.; Teodorescu, V. S.; Stoica, T.; Ciurea, M. L.

2018-01-01

Trilayer memory capacitors with Ge nanocrystals (NCs) floating gate in HfO2 were obtained by magnetron sputtering deposition on p-type Si substrate followed by rapid thermal annealing at relatively low temperature of 600 °C. The frequency dispersion of capacitance and resistance was measured in accumulation regime of Al/HfO2 gate oxide/Ge NCs in HfO2 floating gate/HfO2 tunnel oxide/SiOx/p-Si/Al memory capacitors. For simulation of the frequency dispersion a complex circuit model was used considering an equivalent parallel RC circuit for each layer of the trilayer structure. A series resistance due to metallic contacts and Si substrate was necessary to be included in the model. A very good fit to the experimental data was obtained and the parameters of each layer in the memory capacitor, i.e. capacitances and resistances were determined and in turn the intrinsic material parameters, i.e. dielectric constants and resistivities of layers were evaluated. The results are very important for the study and optimization of the hysteresis behaviour of floating gate memories based on NCs embedded in oxide.

Physico-chemical characterisation of material fractions in household waste

DEFF Research Database (Denmark)

Götze, Ramona; Boldrin, Alessio; Scheutz, Charlotte

2016-01-01

State-of-the-art environmental assessment of waste management systems rely on data for the physico-chemical composition of individual material fractions comprising the waste in question. To derive the necessary inventory data for different scopes and systems, literature data from different sources...... and backgrounds are consulted and combined. This study provides an overview of physico-chemical waste characterisation data for individual waste material fractions available in literature and thereby aims to support the selection of data fitting to a specific scope and the selection of uncertainty ranges related...... to the data selection from literature. Overall, 97 publications were reviewed with respect to employed characterisation method, regional origin of the waste, number of investigated parameters and material fractions and other qualitative aspects. Descriptive statistical analysis of the reported physico...

Metamodel-based inverse method for parameter identification: elastic-plastic damage model

Science.gov (United States)

Huang, Changwu; El Hami, Abdelkhalak; Radi, Bouchaïb

2017-04-01

This article proposed a metamodel-based inverse method for material parameter identification and applies it to elastic-plastic damage model parameter identification. An elastic-plastic damage model is presented and implemented in numerical simulation. The metamodel-based inverse method is proposed in order to overcome the disadvantage in computational cost of the inverse method. In the metamodel-based inverse method, a Kriging metamodel is constructed based on the experimental design in order to model the relationship between material parameters and the objective function values in the inverse problem, and then the optimization procedure is executed by the use of a metamodel. The applications of the presented material model and proposed parameter identification method in the standard A 2017-T4 tensile test prove that the presented elastic-plastic damage model is adequate to describe the material's mechanical behaviour and that the proposed metamodel-based inverse method not only enhances the efficiency of parameter identification but also gives reliable results.

Complete Report on the Development of Welding Parameters for Irradiated Materials

Energy Technology Data Exchange (ETDEWEB)

Frederick, Greg [Electric Power Research Inst. (EPRI), Knoxville, TN (United States); Sutton, Benjamin J. [Electric Power Research Inst. (EPRI), Knoxville, TN (United States); Tatman, Jonathan K. [Electric Power Research Inst. (EPRI), Knoxville, TN (United States); Vance, Mark Christopher [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Clark, Scarlett R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Feng, Zhili [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Miller, Roger G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Chen, Jian [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tang, Wei [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gibson, Brian T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-11-01

The advanced welding facility at the Radiochemical Engineering Development Center of Oak Ridge National Laboratory, which was conceived to enable research and development of weld repair techniques for nuclear power plant life extension, is now operational. The development of the facility and its advanced welding capabilities, along with the model materials for initial welding trials, were funded jointly by the U.S. Department of Energy, Office of Nuclear Energy, Light Water Reactor Sustainability Program, the Electric Power Research Institute, Long Term Operations Program and the Welding and Repair Technology Center, with additional support from Oak Ridge National Laboratory. Welding of irradiated materials was initiated on November 17, 2017, which marked a significant step in the development of the facility and the beginning of extensive welding research and development campaigns on irradiated materials that will eventually produce validated techniques and guidelines for weld repair activities carried out to extend the operational lifetimes of nuclear power plants beyond 60 years. This report summarizes the final steps that were required to complete weld process development, initial irradiated materials welding activities, near-term plans for irradiated materials welding, and plans for post-weld analyses that will be carried out to assess the ability of the advanced welding processes to make repairs on irradiated materials.

Analysis of water sorption isotherms of amorphous food materials by solution thermodynamics with relevance to glass transition: evaluation of plasticizing effect of water by the thermodynamic parameters.

Science.gov (United States)

Shimazaki, Eriko; Tashiro, Akiko; Kumagai, Hitomi; Kumagai, Hitoshi

2017-04-01

Relation between the thermodynamic parameters obtained from water sorption isotherms and the degree of reduction in the glass transition temperature (T g ), accompanied by water sorption, was quantitatively studied. Two well-known glassy food materials namely, wheat gluten and maltodextrin were used as samples. The difference between the chemical potential of water in a solution and that of pure water ([Formula: see text]), the difference between the chemical potential of solid in a solution and that of a pure solid ([Formula: see text]), and the change in the integral Gibbs free energy ([Formula: see text]) were obtained by analyzing the water sorption isotherms using solution thermodynamics. The parameter [Formula: see text] correlated well with ΔT g (≡T g  - T g0 ; where T g0 is the glass transition temperature of dry material), which had been taken to be an index of plasticizing effect. This indicates that plasticizing effect of water on foods can be evaluated through the parameter [Formula: see text].

Magnetic and Superconducting Materials at High Pressures

Energy Technology Data Exchange (ETDEWEB)

Struzhkin, Viktor V. [Carnegie Inst. of Washington, Washington, DC (United States)

2015-03-24

The work concentrates on few important tasks in enabling techniques for search of superconducting compressed hydrogen compounds and pure hydrogen, investigation of mechanisms of high-Tc superconductivity, and exploring new superconducting materials. Along that route we performed several challenging tasks, including discovery of new forms of polyhydrides of alkali metal Na at very high pressures. These experiments help us to establish the experimental environment that will provide important information on the high-pressure properties of hydrogen-rich compounds. Our recent progress in RIXS measurements opens a whole field of strongly correlated 3d materials. We have developed a systematic approach to measure major electronic parameters, like Hubbard energy U, and charge transfer energy Δ, as function of pressure. This technique will enable also RIXS studies of magnetic excitations in iridates and other 5d materials at the L edge, which attract a lot of interest recently. We have developed new magnetic sensing technique based on optically detected magnetic resonance from NV centers in diamond. The technique can be applied to study superconductivity in high-TC materials, to search for magnetic transitions in strongly correlated and itinerant magnetic materials under pressure. Summary of Project Activities; development of high-pressure experimentation platform for exploration of new potential superconductors, metal polyhydrides (including newly discovered alkali metal polyhydrides), and already known superconductors at the limit of static high-pressure techniques; investigation of special classes of superconducting compounds (high-Tc superconductors, new superconducting materials), that may provide new fundamental knowledge and may prove important for application as high-temperature/high-critical parameter superconductors; investigation of the pressure dependence of superconductivity and magnetic/phase transformations in 3d transition metal compounds, including

Development and Testing the Technology of Complex Transformation of Carbohydrates from Vegetable Raw Materials into Bioethanol

Directory of Open Access Journals (Sweden)

S.P. Tsygankov

2013-07-01

Full Text Available Results of development and testing the tentative technology of sweet sorghum and finger millet processing into bioethanol are described. The carbohydrates content and range of the studied vegetable biomass as the raw material is defined. Bioethanol potential output from sugar sorghum and finger millet carbohydrates and key technological parameters of preparation of both types of vegetable raw material for alcohol fermentation are defined. The concept of the tentative technology of bioethanol production from carbohydrate raw material of the first and second generations is offered. Testing of complex transformation of carbohydrates from vegetable raw materials into bioethanol is performed.

Influence of Population Variation of Physiological Parameters in Computational Models of Space Physiology

Science.gov (United States)

Myers, J. G.; Feola, A.; Werner, C.; Nelson, E. S.; Raykin, J.; Samuels, B.; Ethier, C. R.

2016-01-01

The earliest manifestations of Visual Impairment and Intracranial Pressure (VIIP) syndrome become evident after months of spaceflight and include a variety of ophthalmic changes, including posterior globe flattening and distension of the optic nerve sheath. Prevailing evidence links the occurrence of VIIP to the cephalic fluid shift induced by microgravity and the subsequent pressure changes around the optic nerve and eye. Deducing the etiology of VIIP is challenging due to the wide range of physiological parameters that may be influenced by spaceflight and are required to address a realistic spectrum of physiological responses. Here, we report on the application of an efficient approach to interrogating physiological parameter space through computational modeling. Specifically, we assess the influence of uncertainty in input parameters for two models of VIIP syndrome: a lumped-parameter model (LPM) of the cardiovascular and central nervous systems, and a finite-element model (FEM) of the posterior eye, optic nerve head (ONH) and optic nerve sheath. Methods: To investigate the parameter space in each model, we employed Latin hypercube sampling partial rank correlation coefficient (LHSPRCC) strategies. LHS techniques outperform Monte Carlo approaches by enforcing efficient sampling across the entire range of all parameters. The PRCC method estimates the sensitivity of model outputs to these parameters while adjusting for the linear effects of all other inputs. The LPM analysis addressed uncertainties in 42 physiological parameters, such as initial compartmental volume and nominal compartment percentage of total cardiac output in the supine state, while the FEM evaluated the effects on biomechanical strain from uncertainties in 23 material and pressure parameters for the ocular anatomy. Results and Conclusion: The LPM analysis identified several key factors including high sensitivity to the initial fluid distribution. The FEM study found that intraocular pressure and

Neurofitter: a parameter tuning package for a wide range of electrophysiological neuron models

Directory of Open Access Journals (Sweden)

Werner Van Geit

2007-11-01

Full Text Available The increase in available computational power and the higher quality of experimental recordings have turned the tuning of neuron model parameters into a problem that can be solved by automatic global optimization algorithms. Neurofitter is a software tool that interfaces existing neural simulation software and sophisticated optimization algorithms with a new way to compute the error measure. This error measure represents how well a given parameter set is able to reproduce the experimental data. It is based on the phase-plane trajectory density method, which is insensitive to small phase differences between model and data. Neurofitter enables the effortless combination of many different time-dependent data traces into the error measure, allowing the neuroscientist to focus on what are the seminal properties of the model. We show results obtained by applying Neurofitter to a simple single compartmental model and a complex multi-compartmental Purkinje cell (PC model. These examples show that the method is able to solve a variety of tuning problems and demonstrate details of its practical application.

Study of the Wavelength Dependence in Laser Ablation of Advanced Ceramics and Glass-Ceramic Materials in the Nanosecond Range.

Science.gov (United States)

Sola, Daniel; Peña, Jose I

2013-11-19

In this work, geometrical dimensions and ablation yields as a function of the machining method and reference position were studied when advanced ceramics and glass-ceramic materials were machined with pulsed lasers in the nanosecond range. Two laser systems, emitting at 1064 and 532 nm, were used. It was shown that the features obtained depend on whether the substrate is processed by means of pulse bursts or by grooves. In particular, when the samples were processed by grooves, machined depth, removed volume and ablation yields reached their maximum, placing the sample out of focus. It was shown that these characteristics do not depend on the processing conditions, the wavelength or the optical configuration, and that this is intrinsic behavior of the processing method. Furthermore, the existence of a close relation between material hardness and ablation yields was demonstrated.

Applying data mining techniques to determine important parameters in chronic kidney disease and the relations of these parameters to each other.

Science.gov (United States)

Tahmasebian, Shahram; Ghazisaeedi, Marjan; Langarizadeh, Mostafa; Mokhtaran, Mehrshad; Mahdavi-Mazdeh, Mitra; Javadian, Parisa

2017-01-01

Introduction: Chronic kidney disease (CKD) includes a wide range of pathophysiological processes which will be observed along with abnormal function of kidneys and progressive decrease in glomerular filtration rate (GFR). According to the definition decreasing GFR must have been present for at least three months. CKD will eventually result in end-stage kidney disease. In this process different factors play role and finding the relations between effective parameters in this regard can help to prevent or slow progression of this disease. There are always a lot of data being collected from the patients' medical records. This huge array of data can be considered a valuable source for analyzing, exploring and discovering information. Objectives: Using the data mining techniques, the present study tries to specify the effective parameters and also aims to determine their relations with each other in Iranian patients with CKD. Material and Methods: The study population includes 31996 patients with CKD. First, all of the data is registered in the database. Then data mining tools were used to find the hidden rules and relationships between parameters in collected data. Results: After data cleaning based on CRISP-DM (Cross Industry Standard Process for Data Mining) methodology and running mining algorithms on the data in the database the relationships between the effective parameters was specified. Conclusion: This study was done using the data mining method pertaining to the effective factors on patients with CKD.

Sample environment for neutron scattering measurements of internal stresses in engineering materials in the temperature range of 6 K to 300 K.

Science.gov (United States)

Kirichek, O; Timms, J D; Kelleher, J F; Down, R B E; Offer, C D; Kabra, S; Zhang, S Y

2017-02-01

Internal stresses in materials have a considerable effect on material properties including strength, fracture toughness, and fatigue resistance. The ENGIN-X beamline is an engineering science facility at ISIS optimized for the measurement of strain and stress using the atomic lattice planes as a strain gauge. Nowadays, the rapidly rising interest in the mechanical properties of engineering materials at low temperatures has been stimulated by the dynamic development of the cryogenic industry and the advanced applications of the superconductor technology. Here we present the design and discuss the test results of a new cryogenic sample environment system for neutron scattering measurements of internal stresses in engineering materials under a load of up to 100 kN and in the temperature range of 6 K to 300 K. Complete cooling of the system starting from the room temperature down to the base temperature takes around 90 min. Understanding of internal stresses in engineering materials at cryogenic temperatures is vital for the modelling and designing of cutting-edge superconducting magnets and other superconductor based applications.

Identification of strain-rate and thermal sensitive material model with an inverse method

Directory of Open Access Journals (Sweden)

Peroni M.

2010-06-01

Full Text Available This paper describes a numerical inverse method to extract material strength parameters from the experimental data obtained via mechanical tests at different strainrates and temperatures. It will be shown that this procedure is particularly useful to analyse experimental results when the stress-strain fields in the specimen cannot be correctly described via analytical models. This commonly happens in specimens with no regular shape, in specimens with a regular shape when some instability phenomena occur (for example the necking phenomena in tensile tests that create a strongly heterogeneous stress-strain fields or in dynamic tests (where the strain-rate field is not constant due to wave propagation phenomena. Furthermore the developed procedure is useful to take into account thermal phenomena generally affecting high strain-rate tests due to the adiabatic overheating related to the conversion of plastic work. The method presented requires strong effort both from experimental and numerical point of view, anyway it allows to precisely identify the parameters of different material models. This could provide great advantages when high reliability of the material behaviour is necessary. Applicability of this method is particularly indicated for special applications in the field of aerospace engineering, ballistic, crashworthiness studies or particle accelerator technologies, where materials could be submitted to strong plastic deformations at high-strain rate in a wide range of temperature. Thermal softening effect has been investigated in a temperature range between 20°C and 1000°C.

Moisture parameters and fungal communities associated with gypsum drywall in buildings.

Science.gov (United States)

Dedesko, Sandra; Siegel, Jeffrey A

2015-12-08

Uncontrolled excess moisture in buildings is a common problem that can lead to changes in fungal communities. In buildings, moisture parameters can be classified by location and include assessments of moisture in the air, at a surface, or within a material. These parameters are not equivalent in dynamic indoor environments, which makes moisture-induced fungal growth in buildings a complex occurrence. In order to determine the circumstances that lead to such growth, it is essential to have a thorough understanding of in situ moisture measurement, the influence of building factors on moisture parameters, and the levels of these moisture parameters that lead to indoor fungal growth. Currently, there are disagreements in the literature on this topic. A literature review was conducted specifically on moisture-induced fungal growth on gypsum drywall. This review revealed that there is no consistent measurement approach used to characterize moisture in laboratory and field studies, with relative humidity measurements being most common. Additionally, many studies identify a critical moisture value, below which fungal growth will not occur. The values defined by relative humidity encompassed the largest range, while those defined by moisture content exhibited the highest variation. Critical values defined by equilibrium relative humidity were most consistent, and this is likely due to equilibrium relative humidity being the most relevant moisture parameter to microbial growth, since it is a reasonable measure of moisture available at surfaces, where fungi often proliferate. Several sources concur that surface moisture, particularly liquid water, is the prominent factor influencing microbial changes and that moisture in the air and within a material are of lesser importance. However, even if surface moisture is assessed, a single critical moisture level to prevent fungal growth cannot be defined, due to a number of factors, including variations in fungal genera and

Kinetic parameters from thermogravimetric analysis

Science.gov (United States)

Kiefer, Richard L.

1993-01-01

High performance polymeric materials are finding increased use in aerospace applications. Proposed high speed aircraft will require materials to withstand high temperatures in an oxidative atmosphere for long periods of time. It is essential that accurate estimates be made of the performance of these materials at the given conditions of temperature and time. Temperatures of 350 F (177 C) and times of 60,000 to 100,000 hours are anticipated. In order to survey a large number of high performance polymeric materials on a reasonable time scale, some form of accelerated testing must be performed. A knowledge of the rate of a process can be used to predict the lifetime of that process. Thermogravimetric analysis (TGA) has frequently been used to determine kinetic information for degradation reactions in polymeric materials. Flynn and Wall studied a number of methods for using TGA experiments to determine kinetic information in polymer reactions. Kinetic parameters, such as the apparent activation energy and the frequency factor, can be determined in such experiments. Recently, researchers at the McDonnell Douglas Research Laboratory suggested that a graph of the logarithm of the frequency factor against the apparent activation energy can be used to predict long-term thermo-oxidative stability for polymeric materials. Such a graph has been called a kinetic map. In this study, thermogravimetric analyses were performed in air to study the thermo-oxidative degradation of several high performance polymers and to plot their kinetic parameters on a kinetic map.

The combined theoretical and experimental approach to arrive at optimum parameters in friction stir welding

Science.gov (United States)

Jagadeesha, C. B.

2017-12-01

Even though friction stir welding was invented long back (1991) by TWI England, till now there has no method or procedure or approach developed, which helps to obtain quickly optimum or exact parameters yielding good or sound weld. An approach has developed in which an equation has been derived, by which approximate rpm can be obtained and by setting range of rpm ±100 or 50 rpm over approximate rpm and by setting welding speed equal to 60 mm/min or 50 mm/min one can conduct FSW experiment to reach optimum parameters; one can reach quickly to optimum parameters, i.e. desired rpm, and welding speed, which yield sound weld by the approach. This approach can be effectively used to obtain sound welds for all similar and dissimilar combinations of materials such as Steel, Al, Mg, Ti, etc.

Correction of fatigue parameters of concrete using approximation of mechanical-Fracture parameters in time

Czech Academy of Sciences Publication Activity Database

Šimonová, H.; Keršner, Z.; Seitl, Stanislav; Pryl, D.; Pukl, R.

-, č. 1 (2012), s. 57-59 ISSN 1213-3116 R&D Projects: GA ČR(CZ) GAP104/11/0833 Institutional support: RVO:68081723 Keywords : fatigue * concrete * correction * fracture parameters Subject RIV: JL - Materials Fatigue, Friction Mechanics

Transmission Electron Microscope Measures Lattice Parameters

Science.gov (United States)

Pike, William T.

1996-01-01

Convergent-beam microdiffraction (CBM) in thermionic-emission transmission electron microscope (TEM) is technique for measuring lattice parameters of nanometer-sized specimens of crystalline materials. Lattice parameters determined by use of CBM accurate to within few parts in thousand. Technique developed especially for use in quantifying lattice parameters, and thus strains, in epitaxial mismatched-crystal-lattice multilayer structures in multiple-quantum-well and other advanced semiconductor electronic devices. Ability to determine strains in indivdual layers contributes to understanding of novel electronic behaviors of devices.

Surface Irregularity Factor as a Parameter to Evaluate the Fatigue Damage State of CFRP

Directory of Open Access Journals (Sweden)

Pablo Zuluaga-Ramírez

2015-11-01

Full Text Available This work presents an optical non-contact technique to evaluate the fatigue damage state of CFRP structures measuring the irregularity factor of the surface. This factor includes information about surface topology and can be measured easily on field, by techniques such as optical perfilometers. The surface irregularity factor has been correlated with stiffness degradation, which is a well-accepted parameter for the evaluation of the fatigue damage state of composite materials. Constant amplitude fatigue loads (CAL and realistic variable amplitude loads (VAL, representative of real in- flight conditions, have been applied to “dog bone” shaped tensile specimens. It has been shown that the measurement of the surface irregularity parameters can be applied to evaluate the damage state of a structure, and that it is independent of the type of fatigue load that has caused the damage. As a result, this measurement technique is applicable for a wide range of inspections of composite material structures, from pressurized tanks with constant amplitude loads, to variable amplitude loaded aeronautical structures such as wings and empennages, up to automotive and other industrial applications.

Surface Irregularity Factor as a Parameter to Evaluate the Fatigue Damage State of CFRP

Science.gov (United States)

Zuluaga-Ramírez, Pablo; Frövel, Malte; Belenguer, Tomás; Salazar, Félix

2015-01-01

This work presents an optical non-contact technique to evaluate the fatigue damage state of CFRP structures measuring the irregularity factor of the surface. This factor includes information about surface topology and can be measured easily on field, by techniques such as optical perfilometers. The surface irregularity factor has been correlated with stiffness degradation, which is a well-accepted parameter for the evaluation of the fatigue damage state of composite materials. Constant amplitude fatigue loads (CAL) and realistic variable amplitude loads (VAL), representative of real in- flight conditions, have been applied to “dog bone” shaped tensile specimens. It has been shown that the measurement of the surface irregularity parameters can be applied to evaluate the damage state of a structure, and that it is independent of the type of fatigue load that has caused the damage. As a result, this measurement technique is applicable for a wide range of inspections of composite material structures, from pressurized tanks with constant amplitude loads, to variable amplitude loaded aeronautical structures such as wings and empennages, up to automotive and other industrial applications. PMID:28793655

Investigation of the influence of pretreatment parameters on the surface characteristics of amorphous metal for use in power industry

Science.gov (United States)

Nieroda, Jolanta; Rybak, Andrzej; Kmita, Grzegorz; Sitarz, Maciej

2018-05-01

Metallic glasses are metallic materials, which exhibit an amorphous structure. These are mostly three or more component alloys, and some of them are magnetic metals. Materials of this kind are characterized by high electrical resistivity and at the same time exhibit very good magnetic properties (e.g. low-magnetization loss). The above mentioned properties are very useful in electrical engineering industry and this material is more and more popular as a substance for high-efficiency electrical devices production. This industry area is still evolving, and thus even higher efficiency of apparatus based on amorphous material is expected. A raw material must be carefully investigated and characterized before the main production process is started. Presented work contains results of complementary examination of amorphous metal Metglas 2605. Studies involve two ways to obtain clean and oxidized surface with high reactivity, namely degreasing followed by annealing process and plasma treatment. The amorphous metal parameters were examined by means of several techniques: surface free energy (SFE) measurements by sessile drop method, X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and both ex situ and in situ Raman spectroscopy. Additionally, influence of plasma parameters on wetting properties were optimized in systematic way with Design of Experiments (DOE) method. A wide range of used methods allow to fully investigate the amorphous metal material during preliminary preparation of surface. Obtained results provide information about appropriate parameters that should be applied in order to obtain highly reactive surface with functional oxide layer on it.

Some applications on laser material processing

International Nuclear Information System (INIS)

Oros, C.

2005-01-01

An overview of the state-of-the-art in laser material processing for a large types of lasers from IR (CO 2 laser, NdYAG laser) to UV (excimer laser) and different kinds of materials (metals, dielectrics) is given. Laser radiation has found a wide range of applications as machining tool for various kinds of materials processing. The machining geometry, the work piece geometry, the material properties and economic productivity claim for customized systems with special design for beam guiding, shaping and delivery in order to fully utilize the laser radiation for surface processing with optimum efficiency, maximum processing speed and high processing quality. The laser-material interaction involves complex processes of heating, melting, vaporization, ejection of atoms, ions, and molecules, shock waves, plasma initiation and plasma expansion. The interaction is dependent on the laser beam parameters (pulse duration, energy and wavelength), the solid target properties and the surrounding environments condition. Experimental results for laser surface melting and laser ablation are given. Also, assuming the applicability of a one dimensional model for short pulses used, and restricting condition to single-pulse exposure, the temperature rise on the target was calculated taking account of the finite optical absorption depth and pulse duration of the laser

Experimental validation of a kinetic multi-component mechanism in a wide HCCI engine operating range for mixtures of n-heptane, iso-octane and toluene: Influence of EGR parameters

International Nuclear Information System (INIS)

Machrafi, Hatim

2008-01-01

The parameters that are present in exhaust gas recirculation (EGR) are believed to provide an important contribution to control the auto-ignition process of the homogeneous charge compression ignition (HCCI) in an engine. For the investigation of the behaviour of the auto-ignition process, a kinetic multi-component mechanism has been developed in former work, containing 62 reactions and 49 species for mixtures of n-heptane, iso-octane and toluene. This paper presents an experimental validation of this mechanism, comparing the calculated pressure, heat release, ignition delays and CO 2 emissions with experimental data performed on a HCCI engine. The validation is performed in a broad range of EGR parameters by varying the dilution by N 2 and CO 2 from 0 to 46 vol.%, changing the EGR temperature from 30 to 120 deg. C, altering the addition of CO and NO from 0 to 170 ppmv and varying the addition of CH 2 O from 0 to 1400 ppmv. These validations were performed respecting the HCCI conditions for the inlet temperature and the equivalence ratio. The results showed that the mechanism is validated experimentally in dilution ranges going up to 21-30 vol.%, depending on the species of dilution and over the whole range of the EGR temperature. The mechanism is validated over the whole range of CO and CH 2 O addition. As for the addition of NO, the mechanism is validated quantitatively up to 50 ppmv and qualitatively up to 170 ppmv

The effect of multi-directional nanocomposite materials on the vibrational response of thick shell panels with finite length and rested on two-parameter elastic foundations

Science.gov (United States)

Tahouneh, Vahid; Naei, Mohammad Hasan

2016-03-01

The main purpose of this paper is to investigate the effect of bidirectional continuously graded nanocomposite materials on free vibration of thick shell panels rested on elastic foundations. The elastic foundation is considered as a Pasternak model after adding a shear layer to the Winkler model. The panels reinforced by randomly oriented straight single-walled carbon nanotubes are considered. The volume fractions of SWCNTs are assumed to be graded not only in the radial direction, but also in axial direction of the curved panel. This study presents a 2-D six-parameter power-law distribution for CNTs volume fraction of 2-D continuously graded nanocomposite that gives designers a powerful tool for flexible designing of structures under multi-functional requirements. The benefit of using generalized power-law distribution is to illustrate and present useful results arising from symmetric, asymmetric and classic profiles. The material properties are determined in terms of local volume fractions and material properties by Mori-Tanaka scheme. The 2-D differential quadrature method as an efficient numerical tool is used to discretize governing equations and to implement boundary conditions. The fast rate of convergence of the method is shown and results are compared against existing results in literature. Some new results for natural frequencies of the shell are prepared, which include the effects of elastic coefficients of foundation, boundary conditions, material and geometrical parameters. The interesting results indicate that a graded nanocomposite volume fraction in two directions has a higher capability to reduce the natural frequency than conventional 1-D functionally graded nanocomposite materials.

Investigation of Key Parameters of Rock Cracking Using the Expansion of Vermiculite Materials

Science.gov (United States)

Ahn, Chi-Hyung; Hu, Jong Wan

2015-01-01

The demand for the development of underground spaces has been sharply increased in lieu of saturated ground spaces because the residents of cities have steadily increased since the 1980s. The traditional widely used excavation methods (i.e., explosion and shield) have caused many problems, such as noise, vibration, extended schedule, and increased costs. The vibration-free (and explosion-free) excavation method has currently attracted attention in the construction site because of the advantage of definitively solving these issues. For such reason, a new excavation method that utilizes the expansion of vermiculite with relatively fewer defects is proposed in this study. In general, vermiculite materials are rapidly expanded in volume when they receive thermal energy. Expansion pressure can be produced by thermal expansion of vermiculite in a steel tube, and measured by laboratory tests. The experimental tests are performed with various influencing parameters in an effort to seek the optimal condition to effectively increase expansion pressure at the same temperature. Then, calibrated expansion pressure is estimated, and compared to each model. After analyzing test results for expansion pressure, it is verified that vermiculite expanded by heat can provide enough internal pressure to break hard rock during tunneling work. PMID:28793610

Estimation of fracture parameters in foam core materials using thermal techniques

DEFF Research Database (Denmark)

Dulieu-Barton, J. M.; Berggreen, Christian; Boyenval Langlois, C.

2010-01-01

is described. A mode I simulated crack in the form of a machined notch is used to establish the feasibility of the TSA approach to derive stress intensity factors for the foam material. The overall goal is to demonstrate that thermal techniques have the ability to provide deeper insight into the behaviour......The paper presents some initial work on establishing the stress state at a crack tip in PVC foam material using a non-contact infra-red technique known as thermoelastic stress analysis (TSA). A parametric study of the factors that may affect the thermoelastic response of the foam material...

Life Prediction/Reliability Data of Glass-Ceramic Material Determined for Radome Applications

Science.gov (United States)

Choi, Sung R.; Gyekenyesi, John P.

2002-01-01

Brittle materials, ceramics, are candidate materials for a variety of structural applications for a wide range of temperatures. However, the process of slow crack growth, occurring in any loading configuration, limits the service life of structural components. Therefore, it is important to accurately determine the slow crack growth parameters required for component life prediction using an appropriate test methodology. This test methodology also should be useful in determining the influence of component processing and composition variables on the slow crack growth behavior of newly developed or existing materials, thereby allowing the component processing and composition to be tailored and optimized to specific needs. Through the American Society for Testing and Materials (ASTM), the authors recently developed two test methods to determine the life prediction parameters of ceramics. The two test standards, ASTM 1368 for room temperature and ASTM C 1465 for elevated temperatures, were published in the 2001 Annual Book of ASTM Standards, Vol. 15.01. Briefly, the test method employs constant stress-rate (or dynamic fatigue) testing to determine flexural strengths as a function of the applied stress rate. The merit of this test method lies in its simplicity: strengths are measured in a routine manner in flexure at four or more applied stress rates with an appropriate number of test specimens at each applied stress rate. The slow crack growth parameters necessary for life prediction are then determined from a simple relationship between the strength and the applied stress rate. Extensive life prediction testing was conducted at the NASA Glenn Research Center using the developed ASTM C 1368 test method to determine the life prediction parameters of a glass-ceramic material that the Navy will use for radome applications.

Lifetime estimates of a fusion reactor first wall by linear damage summation and strain range partitioning methods

International Nuclear Information System (INIS)

Liu, K.C.; Grossbeck, M.L.

1979-01-01

A generalized model of a first wall made of 20% cold-worked steel was examined for neutron wall loadings ranging from 2 to 5 MW/m 2 . A spectrum of simplified on-off duty cycles was assumed with a 95% burn time. Independent evaluations of cyclic lifetimes were based on two methods: the method of linear damage summation currently being employed for use in ASME high-temperature design Code Case N-47 and that of strain range partitioning being studied for inclusion in the design code. An important point is that the latter method can incorporate a known decrease in ductility for materials subject to irradiation as a parameter, so low-cycle fatigue behavior can be estimated for irradiated material. Lifetimes predicted by the two methods agree reasonably well despite their diversity in concept. Lack of high-cycle fatigue data for the material tested at temperatures within the range of our interest precludes making conclusions on the accuracy of the predicted results, but such data are forthcoming. The analysis includes stress relaxation due to thermal and irradiation-induced creep. Reduced ductility values from irradiations that simulate the environment of the first wall of a fusion reactor were used to estimate the lifetime of the first wall under irradiation. These results indicate that 20% cold-worked type 316 stainless steel could be used as a first-wall material meeting a 8 to 10 MW-year/m 2 lifetime goal for a neutron wall loading of about 2 MW-year/m 2 and a maximum temperature of about 500 0 C

Analytical nondestructive evaluation for materials characterization

International Nuclear Information System (INIS)

Raj, Baldev

1993-01-01

Science and technology of nondestructive testing and evaluation has contributed immensely to the safety and productivity of industrial plants. In recent years, nondestructive evaluation (NDE) has emerged as a frontline research area of equal if not greater technological relevance, for materials characterization as well. A comprehensive range of techniques from qualitative nondestructive testing for quality control of engineering products and materials to quantitative NDE for materials characterization is being used by the engineering industry and materials researchers, for better understanding of the manufacturing practices and materials behaviour. Quantitative NDE is considered essential for ensuring fitness for purpose at the start of the life in case the component has been designed using fracture mechanics parameters. Quantitative NDE is also vital for assessing degradation of material during service. Moreover, quantitative NDE enables characterization of dynamics of certain phenomenon (not achievable by destructive test methodologies) leading to better understanding of the performance of materials in relation to unavoidable defects in the materials. As the next logical step, the need for an analytical approach to NDE is felt. The need and motivation for such an approach is addressed and the means to achieve this objective are identified. It is argued that analytical NDE is essential to meet the challenges of characterization, intelligent processing of materials and life prediction of components and plants. These requirements are of significant importance in the context of recent developments in materials engineering, and for enhancing the competitive advantage of Indian engineering industry in the international market. (author). 9 refs., 3 figs

Thermo-hydro-mechanical tests of buffer material

International Nuclear Information System (INIS)

Pintado, X.; Hassan, Md. M.; Martikainen, J.

2013-10-01

MX-80 bentonite is the reference clay material for the buffer component planned to be used in the deep geological repository for the disposal of spent nuclear fuel in Finland. The buffer presents complex thermo-hydro-mechanical behavior which is modeled with different constitutive models for heat flow, water flow and stress-strain evolution in the buffer. Thermo, hydro and mechanical models need parameters to evaluate the THM-behavior. These modeling parameters were determined by performing series of laboratory experiments as follows: Water retention curve tests were performed on compacted bentonite samples, encompassing a range of initial dry density values from 1397 to 1718 kg/m 3 as the initial water content was around of 5-8 %. The water retention curve was determined by imposing different suctions to the samples and the suctions were then checked using capacitive hygrometer and chilled mirror psychrometer. Oedometer tests were performed on compacted bentonite samples, encompassing a range of initial dry density values from 1590 to 1750 kg/m 3 as the initial water content was around of 6 %. Samples were saturated with tap water, 35 or 70 g/L salt solutions. Infiltration tests were performed on compacted unsaturated bentonite samples, encompassing a range of initial dry density values from 1400 to 1720 kg/m 3 as the initial water content was approximately between 4-7 %. Samples were saturated with tap water, 0.87, 35 or 70 g/L salt solutions. Tortuosity tests were performed on bentonite samples, encompassing a range of dry density values from 1460 to 1750 kg/m 3 and the degree of saturation varied between 33-93 %. Thermal conductivity tests were performed on compacted bentonite samples, encompassing a range of dry density values from 1545 to 1715 kg/m 3 and the degree of saturation varied between 31-88 %. The measurement was performed using a thermal needle probe. The general trend of all analyzed parameters was as expected when dry density, water content, and

Thermo-hydro-mechanical tests of buffer material

Energy Technology Data Exchange (ETDEWEB)

Pintado, X.; Hassan, Md. M.; Martikainen, J. [B and Tech Oy, Helsinki (Finland)

2013-10-15

MX-80 bentonite is the reference clay material for the buffer component planned to be used in the deep geological repository for the disposal of spent nuclear fuel in Finland. The buffer presents complex thermo-hydro-mechanical behavior which is modeled with different constitutive models for heat flow, water flow and stress-strain evolution in the buffer. Thermo, hydro and mechanical models need parameters to evaluate the THM-behavior. These modeling parameters were determined by performing series of laboratory experiments as follows: Water retention curve tests were performed on compacted bentonite samples, encompassing a range of initial dry density values from 1397 to 1718 kg/m{sup 3} as the initial water content was around of 5-8 %. The water retention curve was determined by imposing different suctions to the samples and the suctions were then checked using capacitive hygrometer and chilled mirror psychrometer. Oedometer tests were performed on compacted bentonite samples, encompassing a range of initial dry density values from 1590 to 1750 kg/m{sup 3} as the initial water content was around of 6 %. Samples were saturated with tap water, 35 or 70 g/L salt solutions. Infiltration tests were performed on compacted unsaturated bentonite samples, encompassing a range of initial dry density values from 1400 to 1720 kg/m{sup 3} as the initial water content was approximately between 4-7 %. Samples were saturated with tap water, 0.87, 35 or 70 g/L salt solutions. Tortuosity tests were performed on bentonite samples, encompassing a range of dry density values from 1460 to 1750 kg/m{sup 3} and the degree of saturation varied between 33-93 %. Thermal conductivity tests were performed on compacted bentonite samples, encompassing a range of dry density values from 1545 to 1715 kg/m{sup 3} and the degree of saturation varied between 31-88 %. The measurement was performed using a thermal needle probe. The general trend of all analyzed parameters was as expected when dry

Analysis and synthesis of bianisotropic metasurfaces by using analytical approach based on equivalent parameters

Science.gov (United States)

Danaeifar, Mohammad; Granpayeh, Nosrat

2018-03-01

An analytical method is presented to analyze and synthesize bianisotropic metasurfaces. The equivalent parameters of metasurfaces in terms of meta-atom properties and other specifications of metasurfaces are derived. These parameters are related to electric, magnetic, and electromagnetic/magnetoelectric dipole moments of the bianisotropic media, and they can simplify the analysis of complicated and multilayer structures. A metasurface of split ring resonators is studied as an example demonstrating the proposed method. The optical properties of the meta-atom are explored, and the calculated polarizabilities are applied to find the reflection coefficient and the equivalent parameters of the metasurface. Finally, a structure consisting of two metasurfaces of the split ring resonators is provided, and the proposed analytical method is applied to derive the reflection coefficient. The validity of this analytical approach is verified by full-wave simulations which demonstrate good accuracy of the equivalent parameter method. This method can be used in the analysis and synthesis of bianisotropic metasurfaces with different materials and in different frequency ranges by considering electric, magnetic, and electromagnetic/magnetoelectric dipole moments.

Invited review liquid crystal models of biological materials and silk spinning.

Science.gov (United States)

Rey, Alejandro D; Herrera-Valencia, Edtson E

2012-06-01

A review of thermodynamic, materials science, and rheological liquid crystal models is presented and applied to a wide range of biological liquid crystals, including helicoidal plywoods, biopolymer solutions, and in vivo liquid crystals. The distinguishing characteristics of liquid crystals (self-assembly, packing, defects, functionalities, processability) are discussed in relation to biological materials and the strong correspondence between different synthetic and biological materials is established. Biological polymer processing based on liquid crystalline precursors includes viscoelastic flow to form and shape fibers. Viscoelastic models for nematic and chiral nematics are reviewed and discussed in terms of key parameters that facilitate understanding and quantitative information from optical textures and rheometers. It is shown that viscoelastic modeling the silk spinning process using liquid crystal theories sheds light on textural transitions in the duct of spiders and silk worms as well as on tactoidal drops and interfacial structures. The range and consistency of the predictions demonstrates that the use of mesoscopic liquid crystal models is another tool to develop the science and biomimetic applications of mesogenic biological soft matter. Copyright © 2011 Wiley Periodicals, Inc.

Variation of Bragg curve characteristic induced by changing the position of inhomogeneous material: Geant4 simulation study

Energy Technology Data Exchange (ETDEWEB)

Park, So-Hyun; Jung, Won-Gyun; Suh, Tae-Suk [Catholic University, Seoul (Korea, Republic of); Jang, Hong-Seok; Choi, Byeong-Oak [Seoul St. Mary' s Hospital, Seoul (Korea, Republic of); Rah, Jeong-Eun; Park, Sun-Gyong; Lee, Se-Byeong [National Cancer Center, Ilsan (Korea, Republic of)

2011-02-15

When proton beam passes through the human body, the stopping power and the depth-dose distribution of the proton are influenced by the relative location among adjacent materials or the difference in material conditions. Our study demonstrates the effect of inhomogeneous materials placed in the Plateau and Bragg peak regions of the Bragg curve in water. We evaluated the Bragg peak position, range, penumbra and integrated doses by using the Geant4 simulation toolkit. The positions of inhomogeneities were selected as the proximal 36% and 50% points of the maximum dose, which indicates the location at entrance regions of the Plateau and the Bragg peak, respectively. Bone (density {rho} = 1.85 g/cm{sup 3}) and adipose tissue (density {rho} = 0.92 g/cm{sup 3}) were selected as inhomogeneous materials. The thickness of each material was varied by 0.1 cm between 0.1 cm and 1.0 cm. In addition, the initial energy of the proton beam was changed in 30 MeV steps between 108 MeV and 220 MeV. The effects of inhomogeneous conditions were performed for various parameters: Bragg peak position, range, penumbra width, full width at half maximum and dose of Bragg curve. A dose perturbation was observed in the region of the Bragg peak and inhomogeneous material, especially, When the bone equivalent material was inserted within the Bragg curve. However, there were no significant variations in the other parameters, except for the dose perturbation depending on the inserted location of each material. This study shows the characteristic changes in the Bragg curve due to inhomogeneous materials.

A composite material based on recycled tires

Science.gov (United States)

Malers, L.; Plesuma, R.; Locmele, L.

2009-01-01

The present study is devoted to the elaboration and investigation of a composite material based on mechanically grinded recycled tires and a polymer binder. The correlation between the content of the binder, some technological parameters, and material properties of the composite was clarified. The apparent density, the compressive stress at a 10% strain, the compressive elastic modulus in static and cyclic loadings, and the insulating properties (acoustic and thermal) were the parameters of special interest of the present investigation. It is found that a purposeful variation of material composition and some technological parameters leads to multifunctional composite materials with different and predictable mechanical and insulation properties.

Sci-Thur AM: YIS – 07: Optimizing dual-energy x-ray parameters using a single filter for both high and low-energy images to enhance soft-tissue imaging

International Nuclear Information System (INIS)

Bowman, Wesley; Sattarivand, Mike

2016-01-01

Objective: To optimize dual-energy parameters of ExacTrac stereoscopic x-ray imaging system for lung SBRT patients Methods: Simulated spectra and a lung phantom were used to optimize filter material, thickness, kVps, and weighting factors to obtain bone subtracted dual-energy images. Spektr simulations were used to identify material in the atomic number (Z) range [3–83] based on a metric defined to separate spectrums of high and low energies. Both energies used the same filter due to time constraints of image acquisition in lung SBRT imaging. A lung phantom containing bone, soft tissue, and a tumor mimicking material was imaged with filter thicknesses range [0–1] mm and kVp range [60–140]. A cost function based on contrast-to-noise-ratio of bone, soft tissue, and tumor, as well as image noise content, was defined to optimize filter thickness and kVp. Using the optimized parameters, dual-energy images of anthropomorphic Rando phantom were acquired and evaluated for bone subtraction. Imaging dose was measured with dual-energy technique using tin filtering. Results: Tin was the material of choice providing the best energy separation, non-toxicity, and non-reactiveness. The best soft-tissue-only image in the lung phantom was obtained using 0.3 mm tin and [140, 80] kVp pair. Dual-energy images of the Rando phantom had noticeable bone elimination when compared to no filtration. Dose was lower with tin filtering compared to no filtration. Conclusions: Dual-energy soft-tissue imaging is feasible using ExacTrac stereoscopic imaging system utilizing a single tin filter for both high and low energies and optimized acquisition parameters.

Sci-Thur AM: YIS – 07: Optimizing dual-energy x-ray parameters using a single filter for both high and low-energy images to enhance soft-tissue imaging

Energy Technology Data Exchange (ETDEWEB)

Bowman, Wesley; Sattarivand, Mike [Department of Radiation Oncology, Dalhousie University at Nova Scotia Health Authority, Department of Radiation Oncology, Dalhousie University at Nova Scotia Health Authority (Canada)

2016-08-15

Objective: To optimize dual-energy parameters of ExacTrac stereoscopic x-ray imaging system for lung SBRT patients Methods: Simulated spectra and a lung phantom were used to optimize filter material, thickness, kVps, and weighting factors to obtain bone subtracted dual-energy images. Spektr simulations were used to identify material in the atomic number (Z) range [3–83] based on a metric defined to separate spectrums of high and low energies. Both energies used the same filter due to time constraints of image acquisition in lung SBRT imaging. A lung phantom containing bone, soft tissue, and a tumor mimicking material was imaged with filter thicknesses range [0–1] mm and kVp range [60–140]. A cost function based on contrast-to-noise-ratio of bone, soft tissue, and tumor, as well as image noise content, was defined to optimize filter thickness and kVp. Using the optimized parameters, dual-energy images of anthropomorphic Rando phantom were acquired and evaluated for bone subtraction. Imaging dose was measured with dual-energy technique using tin filtering. Results: Tin was the material of choice providing the best energy separation, non-toxicity, and non-reactiveness. The best soft-tissue-only image in the lung phantom was obtained using 0.3 mm tin and [140, 80] kVp pair. Dual-energy images of the Rando phantom had noticeable bone elimination when compared to no filtration. Dose was lower with tin filtering compared to no filtration. Conclusions: Dual-energy soft-tissue imaging is feasible using ExacTrac stereoscopic imaging system utilizing a single tin filter for both high and low energies and optimized acquisition parameters.

Experiments for practical education in process parameter optimization for selective laser sintering to increase workpiece quality

Science.gov (United States)

Reutterer, Bernd; Traxler, Lukas; Bayer, Natascha; Drauschke, Andreas

2016-04-01

Selective Laser Sintering (SLS) is considered as one of the most important additive manufacturing processes due to component stability and its broad range of usable materials. However the influence of the different process parameters on mechanical workpiece properties is still poorly studied, leading to the fact that further optimization is necessary to increase workpiece quality. In order to investigate the impact of various process parameters, laboratory experiments are implemented to improve the understanding of the SLS limitations and advantages on an educational level. Experiments are based on two different workstations, used to teach students the fundamentals of SLS. First of all a 50 W CO2 laser workstation is used to investigate the interaction of the laser beam with the used material in accordance with varied process parameters to analyze a single-layered test piece. Second of all the FORMIGA P110 laser sintering system from EOS is used to print different 3D test pieces in dependence on various process parameters. Finally quality attributes are tested including warpage, dimension accuracy or tensile strength. For dimension measurements and evaluation of the surface structure a telecentric lens in combination with a camera is used. A tensile test machine allows testing of the tensile strength and the interpreting of stress-strain curves. The developed laboratory experiments are suitable to teach students the influence of processing parameters. In this context they will be able to optimize the input parameters depending on the component which has to be manufactured and to increase the overall quality of the final workpiece.

Recommendations for Measuring Tennis Racket Parameters

Directory of Open Access Journals (Sweden)

Tom Allen

2018-02-01

Full Text Available Tennis rackets have advanced significantly since the invention of the game in 1874, including innovations in both shape and materials. Advances in these design parameters have implications for racket performance, especially swing speed. This study tested one hundred rackets, spanning brands and eras, using simple, portable instruments in order to pilot protocols and make recommendations for streamlining testing procedures for tennis rackets. A wide range of properties were measured and documented for each racket. We suggest that since Transverse and Lateral Moment of Inertia are well correlated, measuring both is not necessary when processing a large number of rackets. In addition, it is also possible to predict the Transverse Moment of Inertia well from models that use simple dimension and mass measurements, which may be preferable in larger studies. Exploring the use of more complex modelling will allow us to better understand the impact of tennis racket design on performance in the future.

The RaDIATE High-Energy Proton Materials Irradiation Experiment at the Brookhaven Linac Isotope Producer Facility

Energy Technology Data Exchange (ETDEWEB)

Ammigan, Kavin; et al.

2017-05-01

The RaDIATE collaboration (Radiation Damage In Accelerator Target Environments) was founded in 2012 to bring together the high-energy accelerator target and nuclear materials communities to address the challenging issue of radiation damage effects in beam-intercepting materials. Success of current and future high intensity accelerator target facilities requires a fundamental understanding of these effects including measurement of materials property data. Toward this goal, the RaDIATE collaboration organized and carried out a materials irradiation run at the Brookhaven Linac Isotope Producer facility (BLIP). The experiment utilized a 181 MeV proton beam to irradiate several capsules, each containing many candidate material samples for various accelerator components. Materials included various grades/alloys of beryllium, graphite, silicon, iridium, titanium, TZM, CuCrZr, and aluminum. Attainable peak damage from an 8-week irradiation run ranges from 0.03 DPA (Be) to 7 DPA (Ir). Helium production is expected to range from 5 appm/DPA (Ir) to 3,000 appm/DPA (Be). The motivation, experimental parameters, as well as the post-irradiation examination plans of this experiment are described.

Determining the Walker exponent and developing a modified Smith-Watson-Topper parameter model

Energy Technology Data Exchange (ETDEWEB)

Lv, Zhiqiang; Huang, Hong Zhong; Wang, Hai Kun; Gao, Huiying; Zuo, Fang Jun [University of Electronic Science and Technology of China, Chengdu (China)

2016-03-15

Mean stress effects significantly influence the fatigue life of components. In general, tensile mean stresses are known to reduce the fatigue life of components, whereas compressive mean stresses are known to increase it. To date, various methods that account for mean stress effects have been studied. In this research, considering the high accuracy of mean stress correction and the difficulty in obtaining the material parameter of the Walker method, a practical method is proposed to describe the material parameter of this method. The test data of various materials are then used to verify the proposed practical method. Furthermore, by applying the Walker material parameter and the Smith-Watson-Topper (SWT) parameter, a modified strain-life model is developed to consider sensitivity to mean stress of materials. In addition, three sets of experimental fatigue data from super alloy GH4133, aluminum alloy 7075-T651, and carbon steel are used to estimate the accuracy of the proposed model. A comparison is also made between the SWT parameter method and the proposed strainlife model. The proposed strain-life model provides more accurate life prediction results than the SWT parameter method.

Standardless quantification approach of TXRF analysis using fundamental parameter method

International Nuclear Information System (INIS)

Szaloki, I.; Taniguchi, K.

2000-01-01

New standardless evaluation procedure based on the fundamental parameter method (FPM) has been developed for TXRF analysis. The theoretical calculation describes the relationship between characteristic intensities and the geometrical parameters of the excitation, detection system and the specimen parameters: size, thickness, angle of the excitation beam to the surface and the optical properties of the specimen holder. Most of the TXRF methods apply empirical calibration, which requires the application of special preparation technique. However, the characteristic lines of the specimen holder (Si Kα,β) present information from the local excitation and geometrical conditions on the substrate surface. On the basis of the theoretically calculation of the substrate characteristic intensity the excitation beam flux can be approximated. Taking into consideration the elements are in the specimen material a system of non-linear equation can be given involving the unknown concentration values and the geometrical and detection parameters. In order to solve this mathematical problem PASCAL software was written, which calculates the sample composition and the average sample thickness by gradient algorithm. Therefore, this quantitative estimation of the specimen composition requires neither external nor internal standard sample. For verification of the theoretical calculation and the numerical procedure, several experiments were carried out using mixed standard solution containing elements of K, Sc, V, Mn, Co and Cu in 0.1 - 10 ppm concentration range. (author)

Optimized 3-D electromagnetic models of composite materials in microwave frequency range: application to EMC characterization of complex media by statistical means

Directory of Open Access Journals (Sweden)

S. Lalléchère

2017-05-01

Full Text Available The aim of this proposal is to demonstrate the ability of tridimensional (3-D electromagnetic modeling tool for the characterization of composite materials in microwave frequency band range. Indeed, an automated procedure is proposed to generate random materials, proceed to 3-D simulations, and compute shielding effectiveness (SE statistics with finite integration technique. In this context, 3-D electromagnetic models rely on random locations of conductive inclusions; results are compared with classical electromagnetic mixing theory (EMT approaches (e.g. Maxwell-Garnett formalism, and dynamic homogenization model (DHM. The article aims to demonstrate the interest of the proposed approach in various domains such as propagation and electromagnetic compatibility (EMC.

InGaN quantum well epilayers morphological evolution under a wide range of MOCVD growth parameter sets

Energy Technology Data Exchange (ETDEWEB)

Florescu, D.I.; Ting, S.M.; Merai, V.N.; Parekh, A.; Lee, D.S.; Armour, E.A.; Quinn, W.E. [Veeco TurboDisc Operations, 394 Elizabeth Avenue, Somerset, NJ 08873 (United States)

2006-06-15

This study exemplifies the use of TappingMode trademark atomic force microscopy (AFM) surface morphology imaging to investigate and optimise the metalorganic chemical vapour deposition (MOCVD) growth conditions and post-growth stability of thin (<40 Aa) InGaN layers with direct implications to the structural and optical properties of blue (460 nm) and green (520 nm) LEDs. InGaN epilayers less than 40 Aa thick of {proportional_to}20% solid phase indium were produced on thick (3-4 {mu}m) 2{sup ''} GaN templates grown on (0001) c-plane sapphire substrates. The morphological evolution of the InGaN material was studied utilising a DI3100 AFM tool. Surface morphology and its correlation with photoluminescence and X-ray diffraction results are discussed for every set of conditions employed. More specifically, the post-growth ambient exposure and thermal stability of the uncapped InGaN epilayers were investigated. In addition, the initial stage of subsequent GaN growth, which is an essential step towards the manufacture of LED active regions, was examined. Based on the above findings, a flexible MOCVD growth parameter space and improved LED constituent layer sequencing techniques have been established leading to more efficient and stable LED devices. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Determination of plant growth rate and growth temperature range from measurement of physiological parameters

Science.gov (United States)

R. S. Criddle; B. N. Smith; L. D. Hansen; J. N. Church

2001-01-01

Many factors influence species range and diversity, but temperature and temperature variability are always major global determinants, irrespective of local constraints. On a global scale, the ranges of many taxa have been observed to increase and their diversity decrease with increasing latitude. On a local scale, gradients in species distribution are observable with...

Grinding Parameter Optimization of Ultrasound-Aided Electrolytic in Process Dressing for Finishing Nanocomposite Ceramics

Directory of Open Access Journals (Sweden)

Fan Chen

2016-01-01

Full Text Available In order to achieve the precision and efficient processing of nanocomposite ceramics, the ultrasound-aided electrolytic in process dressing method was proposed. But how to realize grinding parameter optimization, that is, the maximum processing efficiency, on the premise of the assurance of best workpiece quality is a problem that needs to be solved urgently. Firstly, this research investigated the influence of grinding parameters on material removal rate and critical ductile depth, and their mathematic models based on the existing models were developed to simulate the material removal process. Then, on the basis of parameter sensitivity analysis based on partial derivative, the sensitivity models of material removal rates on grinding parameter were established and computed quantitatively by MATLAB, and the key grinding parameter for optimal grinding process was found. Finally, the theoretical analyses were verified by experiments: the material removal rate increases with the increase of grinding parameters, including grinding depth (ap, axial feeding speed (fa, workpiece speed (Vw, and wheel speed (Vs; the parameter sensitivity of material removal rate was in a descending order as ap>fa>Vw>Vs; the most sensitive parameter (ap was optimized and it was found that the better machining result has been obtained when ap was about 3.73 μm.

Expert-guided optimization for 3D printing of soft and liquid materials

Science.gov (United States)

Abdollahi, Sara; Davis, Alexander; Miller, John H.

2018-01-01

Additive manufacturing (AM) has rapidly emerged as a disruptive technology to build mechanical parts, enabling increased design complexity, low-cost customization and an ever-increasing range of materials. Yet these capabilities have also created an immense challenge in optimizing the large number of process parameters in order achieve a high-performance part. This is especially true for AM of soft, deformable materials and for liquid-like resins that require experimental printing methods. Here, we developed an expert-guided optimization (EGO) strategy to provide structure in exploring and improving the 3D printing of liquid polydimethylsiloxane (PDMS) elastomer resin. EGO uses three steps, starting first with expert screening to select the parameter space, factors, and factor levels. Second is a hill-climbing algorithm to search the parameter space defined by the expert for the best set of parameters. Third is expert decision making to try new factors or a new parameter space to improve on the best current solution. We applied the algorithm to two calibration objects, a hollow cylinder and a five-sided hollow cube that were evaluated based on a multi-factor scoring system. The optimum print settings were then used to print complex PDMS and epoxy 3D objects, including a twisted vase, water drop, toe, and ear, at a level of detail and fidelity previously not obtained. PMID:29621286

Expert-guided optimization for 3D printing of soft and liquid materials.

Science.gov (United States)

Abdollahi, Sara; Davis, Alexander; Miller, John H; Feinberg, Adam W

2018-01-01

Additive manufacturing (AM) has rapidly emerged as a disruptive technology to build mechanical parts, enabling increased design complexity, low-cost customization and an ever-increasing range of materials. Yet these capabilities have also created an immense challenge in optimizing the large number of process parameters in order achieve a high-performance part. This is especially true for AM of soft, deformable materials and for liquid-like resins that require experimental printing methods. Here, we developed an expert-guided optimization (EGO) strategy to provide structure in exploring and improving the 3D printing of liquid polydimethylsiloxane (PDMS) elastomer resin. EGO uses three steps, starting first with expert screening to select the parameter space, factors, and factor levels. Second is a hill-climbing algorithm to search the parameter space defined by the expert for the best set of parameters. Third is expert decision making to try new factors or a new parameter space to improve on the best current solution. We applied the algorithm to two calibration objects, a hollow cylinder and a five-sided hollow cube that were evaluated based on a multi-factor scoring system. The optimum print settings were then used to print complex PDMS and epoxy 3D objects, including a twisted vase, water drop, toe, and ear, at a level of detail and fidelity previously not obtained.

(AJST) DETERMINATION OF THE PARAMETERS FOR DESIGN OF ...

African Journals Online (AJOL)

of creep and recovery within the temperature range 30°C - 50°C and for stresses ranging from. 0.781 to 1.563 ... Estimates were also provided for the expected permanent expansion of the material under load, .... MATERIALS AND METHODS.

Experimental validation of a kinetic multi-component mechanism in a wide HCCI engine operating range for mixtures of n-heptane, iso-octane and toluene: Influence of EGR parameters

Energy Technology Data Exchange (ETDEWEB)

Machrafi, Hatim [LGPPTS, Ecole Nationale Superieure de Chimie de Paris/ Universite Pierre et Marie Curie (Paris 6), 11, rue de Pierre et Marie Curie, 75231 Paris Cedex 05 (France)

2008-11-15

The parameters that are present in exhaust gas recirculation (EGR) are believed to provide an important contribution to control the auto-ignition process of the homogeneous charge compression ignition (HCCI) in an engine. For the investigation of the behaviour of the auto-ignition process, a kinetic multi-component mechanism has been developed in former work, containing 62 reactions and 49 species for mixtures of n-heptane, iso-octane and toluene. This paper presents an experimental validation of this mechanism, comparing the calculated pressure, heat release, ignition delays and CO{sub 2} emissions with experimental data performed on a HCCI engine. The validation is performed in a broad range of EGR parameters by varying the dilution by N{sub 2} and CO{sub 2} from 0 to 46 vol.%, changing the EGR temperature from 30 to 120 C, altering the addition of CO and NO from 0 to 170 ppmv and varying the addition of CH{sub 2}O from 0 to 1400 ppmv. These validations were performed respecting the HCCI conditions for the inlet temperature and the equivalence ratio. The results showed that the mechanism is validated experimentally in dilution ranges going up to 21-30 vol.%, depending on the species of dilution and over the whole range of the EGR temperature. The mechanism is validated over the whole range of CO and CH{sub 2}O addition. As for the addition of NO, the mechanism is validated quantitatively up to 50 ppmv and qualitatively up to 170 ppmv. (author)

Complex permeability and permittivity variation of carbonyl iron rubber in the frequency range of 2 to 18 GHz

Directory of Open Access Journals (Sweden)

Adriana Medeiros Gama

2010-04-01

Full Text Available The complex dielectric permittivity (e and magnetic permeability (m of Radar Absorbing Materials (RAM based on metallic magnetic particles (carbonyl iron particles embedded in a dielectric matrix (silicon rubber have been studied in the frequency range of 2 to 18 GHz. The relative permeability and permittivity of carbonyl iron-silicon composites for various mass fractions are measured by the transmission/reflection method using a vector network analyzer. The concentration dependence of permittivity and permeability on the frequency is analyzed. In a general way, the results show that e´ parameter shows a more significant variation among the evaluated parameters (e”, m”, m’. The comparison of dielectric and magnetic loss tangents (e”/e” and m”/m’, respectively shows more clearly the variation of both parameters (e and m according to the frequency. It is also observed that higher carbonyl iron content fractions favor both dielectric and magnetic loss tangents.

Optimisation of material discrimination using spectral CT

International Nuclear Information System (INIS)

Nik, S.J.; Meyer, J.; Watts, R.

2010-01-01

Full text: Spectral computed tomography (CT) using novel X-ray photon counting detectors (PCDs) with energy resolving capabilities is capable of providing energy-selective images. This extra energy information may allow materials such as iodine and calcium, or water and fat to be distinguished. PCDs have energy thresholds, enabling the classification of photons into multiple energy bins. The inform tion content of spectral CT images depends on how the photons are grouped together. [n this work, a method is presented to optimise energy windows for maximum material discrimination. Given a combination of thicknesses, the reference number of expected photons in each energy bin is computed using the Bee Lambert equation. A similar calculation is performed for an exhaustive range of thicknesses and the number of photons in each case is com pared to the reference, allowing a statistical map of the uncertainty in thickness parameters to be constructed. The 63%-confidence region in the two-dimensional thickness space is a representation of how optimal the bins are for material separation. The model is demonstrated with 0.1 mm of iodine and 2.2 mm of calcium using two adjacent bins encompassing the entire energy range. Bins bordering at the iodine k-edge of 33.2 keY are found to be optimal. When compared to two abutted energy bins with equal incident counts as used in the literature (bordering at 54 keY), the thickness uncertainties are reduced from approximately 4% to less than I % (see Figure). This approach has been developed for two materials and is expandable to an arbitrary number of materials and bins.

Energy dependence of radiation interaction parameters of some organic compounds

Science.gov (United States)

Singh, Mohinder; Tondon, Akash; Sandhu, B. S.; Singh, Bhajan

2018-04-01

Gamma rays interact with a material through photoelectric absorption, Compton scattering, Rayleigh scattering and Pair production in the intermediate energy range. The probability of occurrence of a particular type of process depends on the energy of incident gamma rays, atomic number of the material, scattering angle and geometrical conditions. Various radiological parameters for organic compounds, namely ethylene glycol (C2H6O2), propylene glycol (C3H8O2), glycerin (C3H8O3), isoamyl alcohol (C5H12O), butanone (C4H8O), acetophenone (C8H8O2), cyclohexanone (C6H10O), furfural (C5H4O2), benzaldehyde (C7H6O), cinnamaldehyde (C9H8O), glutaraldehyde (C5H8O2), aniline (C6H7N), benzyl amine (C6H7N), nitrobenzene (C6H5NO2), ethyl benzene (C8H10), ethyl formate (C3H6O2) and water (H2O) are presented at 81, 122, 356 and 511 keV energies employing NaI(Tl) scintillation detector in narrow-beam transmission geometry. The radiation interaction parameters such as mass attenuation, molar extinction and mass energy absorption coefficients, half value layer, total atomic and effective electronic cross-sections and CT number have been evaluated for these organic compounds. The general trend of values of mass attenuation coefficients, half value layer, molar extinction coefficients, total atomic and effective electronic cross-sections and mass energy absorption coefficients shows a decrease with increase in incident gamma photon energy. The values of CT number are found to increases linearly with increase of effective atomic number (Zeff). The variation in CT number around Zeff ≈ 3.3 shows the peak like structure with respect to water and the correlation between CT number and linear attenuation coefficient is about 0.99. Appropriate equations are fitted to these experimentally determined parameters for the organic compounds at incident photon energy ranging from 81 keV to 511 keV used in the present study. Experimental values are compared with the theoretical data obtained using Win

Efficient Space Hardy Thermoelectric Materials with Broad Temperature Range, Phase I

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National Aeronautics and Space Administration — The goal of this work is developing new thermoelectric materials for use in fabricating solid state cooling devices and electrical power generators, which are 200 to...

Efficient Space Hardy Thermoelectric Materials with Broad Temperature Range, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — The goal of this work is to develop new thermoelectric materials for use in fabricating solid state cooling devices and electrical power generators, which are 200 to...

Transitional Phenomena on Phase Change Materials

Directory of Open Access Journals (Sweden)

Wójcik Tadeusz M.

2014-03-01

Full Text Available One of the most significant problem with technology development is transferring of large heat fluxes, which requires constant heat transfer temperature (in the specified temperature range. This problem concern mainly the nuclear energetics, space technologies, military technologies and most of all electronics containing integrated circuits with very large scale of integrations. Intensive heat transfer and thermal energy storage are possible by the use of phase change materials (PCMs. In the paper there are presented preliminary results of research on the use of liquid-gas (L-G PCMs and solid-solid phase change materials (S-S PCMs. For L-G PCMs the boiling characteristics were determined by increasing and decreasing the heat flux, which for certain sets of structural parameters of the heating surface and the physical properties of the liquid induce a variety of forms of transitional phenomena. Thermal energy storage is much more effective when using PCMs than sensible heat.

X-ray Micro-Tomography of Ablative Heat Shield Materials

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Panerai, Francesco; Ferguson, Joseph; Borner, Arnaud; Mansour, Nagi N.; Barnard, Harold S.; MacDowell, Alastair A.; Parkinson, Dilworth Y.

2016-01-01

X-ray micro-tomography is a non-destructive characterization technique that allows imaging of materials structures with voxel sizes in the micrometer range. This level of resolution makes the technique very attractive for imaging porous ablators used in hypersonic entry systems. Besides providing a high fidelity description of the material architecture, micro-tomography enables computations of bulk material properties and simulations of micro-scale phenomena. This presentation provides an overview of a collaborative effort between NASA Ames Research Center and Lawrence Berkeley National Laboratory, aimed at developing micro-tomography experiments and simulations for porous ablative materials. Measurements are carried using x-rays from the Advanced Light Source at Berkeley Lab on different classes of ablative materials used in NASA entry systems. Challenges, strengths and limitations of the technique for imaging materials such as lightweight carbon-phenolic systems and woven textiles are discussed. Computational tools developed to perform numerical simulations based on micro-tomography are described. These enable computations of material properties such as permeability, thermal and radiative conductivity, tortuosity and other parameters that are used in ablator response models. Finally, we present the design of environmental cells that enable imaging materials under simulated operational conditions, such as high temperature, mechanical loads and oxidizing atmospheres.Keywords: Micro-tomography, Porous media, Ablation

Evaluation of J and CTOD (Crack Tip Opening Displacement) fracture parameters for pipeline steels using Single Edge Notch Tension SE(T) specimens

Energy Technology Data Exchange (ETDEWEB)

Paredes Tobar, Lenin Marcelo; Ruggieri, Claudio [Universidade de Sao Paulo (USP), SP (Brazil). Escola Politecnica. Dept. de Engenharia Naval e Oceanica

2009-12-19

This work presents an evaluation procedure to determine the elastic-plastic J-integral and CTOD for pin-loaded and clamped single edge notch tension (SE(T)) specimens based upon the eta-method. The primary objective is to derive estimation equations applicable to determine J and CTOD fracture parameters for a wide range of a/W-ratios and material flow properties. Very detailed non-linear finite element analyses for plane-strain and full-thickness, 3-D models provide the evolution of load with increased crack mouth opening displacement which is required for the estimation procedure. The present analyses, when taken together with previous studies provide a fairly extensive body of results which serve to determine parameters J and CTOD for different materials using tension specimens with varying geometries. (author)

Machine learning of parameters for accurate semiempirical quantum chemical calculations

International Nuclear Information System (INIS)

Dral, Pavlo O.; Lilienfeld, O. Anatole von; Thiel, Walter

2015-01-01

We investigate possible improvements in the accuracy of semiempirical quantum chemistry (SQC) methods through the use of machine learning (ML) models for the parameters. For a given class of compounds, ML techniques require sufficiently large training sets to develop ML models that can be used for adapting SQC parameters to reflect changes in molecular composition and geometry. The ML-SQC approach allows the automatic tuning of SQC parameters for individual molecules, thereby improving the accuracy without deteriorating transferability to molecules with molecular descriptors very different from those in the training set. The performance of this approach is demonstrated for the semiempirical OM2 method using a set of 6095 constitutional isomers C 7 H 10 O 2 , for which accurate ab initio atomization enthalpies are available. The ML-OM2 results show improved average accuracy and a much reduced error range compared with those of standard OM2 results, with mean absolute errors in atomization enthalpies dropping from 6.3 to 1.7 kcal/mol. They are also found to be superior to the results from specific OM2 reparameterizations (rOM2) for the same set of isomers. The ML-SQC approach thus holds promise for fast and reasonably accurate high-throughput screening of materials and molecules

Analysis of the influence of the cutting edge geometry on parameters of the perforation process for conveyor and transmission belts

Directory of Open Access Journals (Sweden)

Wojtkowiak Dominik

2018-01-01

Full Text Available Perforated belts, which are used in vacuum conveyor belts, can have significantly different mechanical properties like strength and elasticity due to a variety of used materials and can have different thickness from very thin (0,7 mm to thick belts (6 mm. In order to design a complex machine for mechanical perforation, which can perforate whole range of belts, it is necessary to research the influence of the cutting edge geometry on the parameters of the perforation process. Three most important parameters, which describe the perforation process are the cutting force, the velocity and the temperature of the piercing punch. The results presented in this paper consider two different types of punching (a piercing punch with the punching die or with the reducer plate and different cutting edge directions, angles, diameters and material properties. Test were made for different groups of composites belts – with polyurethane and polyester fabric, polyamide core or aramid-fibre reinforced polymers. The main goal of this research is to specify effective tools and parameters of the perforation process for each group of composites belts.

Association between mild cognitive impairment and trajectory-based spatial parameters during timed up and go test using a laser range sensor.

Science.gov (United States)

Nishiguchi, Shu; Yorozu, Ayanori; Adachi, Daiki; Takahashi, Masaki; Aoyama, Tomoki

2017-08-08

The Timed Up and Go (TUG) test may be a useful tool to detect not only mobility impairment but also possible cognitive impairment. In this cross-sectional study, we used the TUG test to investigate the associations between trajectory-based spatial parameters measured by laser range sensor (LRS) and cognitive impairment in community-dwelling older adults. The participants were 63 community-dwelling older adults (mean age, 73.0 ± 6.3 years). The trajectory-based spatial parameters during the TUG test were measured using an LRS. In each forward and backward phase, we calculated the minimum distance from the marker, the maximum distance from the x-axis (center line), the length of the trajectories, and the area of region surrounded by the trajectory of the center of gravity and the x-axis (center line). We measured mild cognitive impairment using the Mini-Mental State Examination score (26/27 was the cut-off score for defining mild cognitive impairment). Compared with participants with normal cognitive function, those with mild cognitive impairment exhibited the following trajectory-based spatial parameters: short minimum distance from the marker (p = 0.044), narrow area of center of gravity in the forward phase (p = 0.012), and a large forward/whole phase ratio of the area of the center of gravity (p = 0.026) during the TUG test. In multivariate logistic regression analyses, a short minimum distance from the marker (odds ratio [OR]: 0.82, 95% confidence interval [CI]: 0.69-0.98), narrow area of the center of gravity in the forward phase (OR: 0.01, 95% CI: 0.00-0.36), and large forward/whole phase ratio of the area of the center of gravity (OR: 0.94, 95% CI: 0.88-0.99) were independently associated with mild cognitive impairment. In conclusion, our results indicate that some of the trajectory-based spatial parameters measured by LRS during the TUG test were independently associated with cognitive impairment in older adults. In particular, older adults with

Materials Informatics: Statistical Modeling in Material Science.

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Yosipof, Abraham; Shimanovich, Klimentiy; Senderowitz, Hanoch

2016-12-01

Material informatics is engaged with the application of informatic principles to materials science in order to assist in the discovery and development of new materials. Central to the field is the application of data mining techniques and in particular machine learning approaches, often referred to as Quantitative Structure Activity Relationship (QSAR) modeling, to derive predictive models for a variety of materials-related "activities". Such models can accelerate the development of new materials with favorable properties and provide insight into the factors governing these properties. Here we provide a comparison between medicinal chemistry/drug design and materials-related QSAR modeling and highlight the importance of developing new, materials-specific descriptors. We survey some of the most recent QSAR models developed in materials science with focus on energetic materials and on solar cells. Finally we present new examples of material-informatic analyses of solar cells libraries produced from metal oxides using combinatorial material synthesis. Different analyses lead to interesting physical insights as well as to the design of new cells with potentially improved photovoltaic parameters. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Active Surfaces and Interfaces of Soft Materials

Science.gov (United States)

Wang, Qiming

A variety of intriguing surface patterns have been observed on developing natural systems, ranging from corrugated surface of white blood cells at nanometer scales to wrinkled dog skins at millimeter scales. To mimetically harness functionalities of natural morphologies, artificial transformative skin systems by using soft active materials have been rationally designed to generate versatile patterns for a variety of engineering applications. The study of the mechanics and design of these dynamic surface patterns on soft active materials are both physically interesting and technologically important. This dissertation starts with studying abundant surface patterns in Nature by constructing a unified phase diagram of surface instabilities on soft materials with minimum numbers of physical parameters. Guided by this integrated phase diagram, an electroactive system is designed to investigate a variety of electrically-induced surface instabilities of elastomers, including electro-creasing, electro-cratering, electro-wrinkling and electro-cavitation. Combing experimental, theoretical and computational methods, the initiation, evolution and transition of these instabilities are analyzed. To apply these dynamic surface instabilities to serving engineering and biology, new techniques of Dynamic Electrostatic Lithography and electroactive anti-biofouling are demonstrated.

Characterization of appendage weld quality by on line monitoring of electrical parameters