Purification, Characterization and Antibacterial Mechanism of ...

African Journals Online (AJOL)

Purpose: To carry out the extraction, purification and biological characterization, and assess the antibacterial activity of bacteriocin from Lactobacillus acidophilus XH1. Methods: Chloroform extraction method was used for bacteriocin extraction while characterization of bacteriocin was carried out by flat-dug well agar ...

Thermophysical and mechanical characterization of advanced materials for the LHC collimation system

CERN Document Server

AUTHOR|(CDS)2129177; Guinchard, Michael

The aim of the thesis is to describe the methods employed for the thermo-physical and mechanical characterization and to show the results of the campaign conducted over two ceramic matrix composites, CFC FS140® and MG-6403-Fc, which are candidates as jaws materials in the LHC collimation system. The work was conducted at the European Organization for Nuclear Research (CERN, Geneva), in the framework of the R&D activities done by the EN department. The goal of this project is to develop and characterize materials able to withstand highly energetic particles interactions to protect the accelerator’s components and to clean the beam. In the first part of the thesis, the instruments employed for the thermal and mechanical analysis are studied, from the mathematical models to the standard test methods. These instruments are: horizontal push-rod dilatometer, differential scanning calorimeter, laser flash apparatus and universal testing machine. The results of the analysis show lower thermal and electrical co...

THERMOPHYSICAL AND MECHANICAL CHARACTERIZATION OF ADVANCED MATERIALS FOR THE LHC COLLIMATION SYSTEM

CERN Document Server

Bianchi, Laura

2017-01-01

The aim of the thesis is to describe the methods employed for the thermo-physical and mechanical characterization and to show the results of the campaign conducted over two ceramic matrix composites, CFC FS140® and MG-6403-Fc, which are candidates as jaws materials in the LHC collimation system. The work was conducted at the European Organization for Nuclear Research (CERN, Geneva), in the framework of the R&D activities done by the EN department. The goal of this project is to develop and characterize materials able to withstand highly energetic particles interactions to protect the accelerator’s components and to clean the beam. In the first part of the thesis, the instruments employed for the thermal and mechanical analysis are studied, from the mathematical models to the standard test methods. These instruments are: horizontal push-rod dilatometer, differential scanning calorimeter, laser flash apparatus and universal testing machine. The results of the analysis show lower thermal and electrical co...

Mechanical characterization of auxetic stainless steel thin sheets with reentrant structure

Science.gov (United States)

Lekesiz, H.; Bhullar, S. K.; Karaca, A. A.; Jun, M. B. G.

2017-08-01

Smart materials in auxetic form present a great potential for various medical applications due to their unique deformation mechanisms along with durable infrastructure. Both analytical and finite element (FE) models are extensively used in literature to characterize mechanical response of auxetic structures but these structures are mostly thick enough to be considered as bulk material and 3D inherently. Auxetic plates in very thin form, a.e. foil, may bring numerous advantages such as very light design and better biodegradability when needed. However, there is a gap in literature on mechanical characterization of auxetic thin plates. In this study, structural analysis of very thin auxetic plates under uniaxial loading is investigated using both FE method and experimental method. 25 μm thick stainless steel (316L) plates are fabricated with reentrant texture for three different unit cell dimensions and tested under uniaxial loading using universal testing machine. 25 and 50 μm thick sheets with same cell dimensions were analyzed using implicit transient FE model including strain hardening and failure behaviors. FE results cover all the deformation schemes seen in actual tests and total deformation level matches with test results. Effect of plate thickness and cell geometry on auxetic behavior is discussed in detail using FE results. Finally, based on FE analysis results, an optimum geometry for prolonged auxetic behavior, high flexibility and high durability is suggested for future potential applications.

Mechanical characterization of biocompatible thin film materials by scanning along micro-machined cantilevers for micro-/nano-system

International Nuclear Information System (INIS)

He, J.H.; Luo, J.K.; Le, H.R.; Moore, D.F.

2006-01-01

Mechanical characterization is vital for the design of micro-/nano-electro-mechanical system (MEMS/NEMS). This paper describes a new characterization method to extract the mechanical properties of the thin film materials, which is simple, inexpensive and applicable to a wide range of materials including biocompatible ones described in this paper. The beams of the material under tests, are patterned by laser micro-machining and released by alkaline etch. A surface profilometer is used to scan along micro-machined cantilevers and produce a bending profile, from which the Young's modulus can be extracted. Biocompatible SiN x , SiC and nanocrystal diamond cantilevers have been fabricated and their Young's modulus has been evaluated as 154 ± 12, 360 ± 50 and 504 ± 50 GPa, respectively, which is consistent with those measured by nano-indentation. Residual stress gradient has also been extracted by surface profilometer, which is comparable with the results inferred from ZYGO interferometer measurements. This method can be extended to atomic force microscopy stylus or nanometer-stylus profilometer for Bio-NEMS mechanical characterization

Mechanical and Thermal Characterization of Silica Nanocomposites

Science.gov (United States)

Cunningham, Anthony Lamar

Polymer nanocomposites are a class of materials containing nanoparticles with a large interfacial surface area. Only a small quantity of nanoparticles are needed to provide superior multifunctional properties; such as mechanical, thermal, electrical, and moisture absorption properties in polymers. Nanoparticles tend to agglomerate, so special techniques are required for homogeneous distribution. Nanosilica is now readily available as colloidal sols, for example; Nanopox RTM F400 (supplied by Evonik Nanoresins AG, Germany). The nanoparticles are first synthesized from aqueous sodium silicate solution, and then undergo a surface modification process with organosilane and matrix exchange. F400 contains 40%wt silica nanoparticles colloidally dispersed in a DGEBA epoxy resin. The mean particle diameter is about 20 nm with a narrow distribution range of about 5 to 35 nm. The objectives of this study are to develop a reproducible processing method for nanosilica enhanced resin systems used in the manufacturing of fiber reinforced composites that will be characterized for mechanical and thermal properties. Research has concluded that shows improvements in the properties of the matrix material when processed in loading variations of 0 to 25%wt silica nanoparticles. The loadings were also used to manufacture fiberglass reinforced nanocomposite laminates and also tested for mechanical and thermal properties.

A new mechanical characterization method for thin film microactuators and its application to NiTiCi shape memory alloy

International Nuclear Information System (INIS)

Seward, K P

1999-01-01

In an effort to develop a more full characterization tool of shape memory alloys, a new technique is presented for the mechanical characterization of microactuators and applied to SMA thin films. A test instrument was designed to utilize a spring-loaded transducer in measuring displacements with resolution of 1.5 pm and forces with resolution of 0.2 mN. Employing an out-of-plane loading method for freestanding SMA thin films, strain resolution of 30(mu)(epsilon) and stress resolution of 2.5 MPa were achieved. This new testing method is presented against previous SMA characterization methods for purposes of comparison. Four mm long, 2(micro)m thick NiTiCu ligaments suspended across open windows were bulk micromachined for use in the out-of-plane stress and strain measurements. The fabrication process used to micromachine the ligaments is presented step-by-step, alongside methods of fabrication that failed to produce testable ligaments. Static analysis showed that 63% of the applied strain was recovered while ligaments were subjected to tensile stresses of 870 MPa. In terms of recoverable stress and recoverable strain, the ligaments achieved maximum recovery of 700 MPa and 3.0% strain. No permanent deformations were seen in any ligament during deflection measurements. Maximum actuation forces and displacements produced by the 4 mm ligaments situated on 1 cm square test chips were 56 mN and 300(micro)m, respectively. Fatigue analysis of the ligaments showed degradation in recoverable strain from 0.33% to 0.24% with 200,000 cycles, corresponding to deflections of 90(micro)m and forces of 25 mN. Cycling also produced a wavering shape memory effect late in ligament life, leading to broad inconsistencies of as much as 35% deviation from average. Unexpected phenomena like stress-induced martensitic twinning that leads to less recoverable stress and the shape memory behavior of long life devices are addressed. Finally, a model for design of microactuators using shape memory

Characterization of the Mechanical Stress-Strain Performance of Aerospace Alloy Materials Using Frequency-Domain Photoacoustic Ultrasound and Photothermal Methods: An FEM Approach

Science.gov (United States)

Huan, Huiting; Mandelis, Andreas; Liu, Lixian

2018-04-01

Determining and keeping track of a material's mechanical performance is very important for safety in the aerospace industry. The mechanical strength of alloy materials is precisely quantified in terms of its stress-strain relation. It has been proven that frequency-domain photothermoacoustic (FD-PTA) techniques are effective methods for characterizing the stress-strain relation of metallic alloys. PTA methodologies include photothermal (PT) diffusion and laser thermoelastic photoacoustic ultrasound (PAUS) generation which must be separately discussed because the relevant frequency ranges and signal detection principles are widely different. In this paper, a detailed theoretical analysis of the connection between thermoelastic parameters and stress/strain tensor is presented with respect to FD-PTA nondestructive testing. Based on the theoretical model, a finite element method (FEM) was further implemented to simulate the PT and PAUS signals at very different frequency ranges as an important analysis tool of experimental data. The change in the stress-strain relation has an impact on both thermal and elastic properties, verified by FEM and results/signals from both PT and PAUS experiments.

Characterization of Tensile Mechanical Behavior of MSCs/PLCL Hybrid Layered Sheet

Directory of Open Access Journals (Sweden)

Azizah Intan Pangesty

2016-06-01

Full Text Available A layered construct was developed by combining a porous polymer sheet and a cell sheet as a tissue engineered vascular patch. The primary objective of this study is to investigate the influence of mesenchymal stem cells (MSCs sheet on the tensile mechanical properties of porous poly-(l-lactide-co-ε-caprolactone (PLCL sheet. The porous PLCL sheet was fabricated by the solid-liquid phase separation method and the following freeze-drying method. The MSCs sheet, prepared by the temperature-responsive dish, was then layered on the top of the PLCL sheet and cultured for 2 weeks. During the in vitro study, cellular properties such as cell infiltration, spreading and proliferation were evaluated. Tensile test of the layered construct was performed periodically to characterize the tensile mechanical behavior. The tensile properties were then correlated with the cellular properties to understand the effect of MSCs sheet on the variation of the mechanical behavior during the in vitro study. It was found that MSCs from the cell sheet were able to migrate into the PLCL sheet and actively proliferated into the porous structure then formed a new layer of MSCs on the opposite surface of the PLCL sheet. Mechanical evaluation revealed that the PLCL sheet with MSCs showed enhancement of tensile strength and strain energy density at the first week of culture which is characterized as the effect of MSCs proliferation and its infiltration into the porous structure of the PLCL sheet. New technique was presented to develop tissue engineered patch by combining MSCs sheet and porous PLCL sheet, and it is expected that the layered patch may prolong biomechanical stability when implanted in vivo.

A Novel Physical Sensing Principle for Liquid Characterization Using Paper-Based Hygro-Mechanical Systems (PB-HMS).

Science.gov (United States)

Perez-Cruz, Angel; Stiharu, Ion; Dominguez-Gonzalez, Aurelio

2017-07-20

In recent years paper-based microfluidic systems have emerged as versatile tools for developing sensors in different areas. In this work; we report a novel physical sensing principle for the characterization of liquids using a paper-based hygro-mechanical system (PB-HMS). The PB-HMS is formed by the interaction of liquid droplets and paper-based mini-structures such as cantilever beams. The proposed principle takes advantage of the hygroscopic properties of paper to produce hygro-mechanical motion. The dynamic response of the PB-HMS reveals information about the tested liquid that can be applied to characterize certain properties of liquids. A suggested method to characterize liquids by means of the proposed principle is introduced. The experimental results show the feasibility of such a method. It is expected that the proposed principle may be applied to sense properties of liquids in different applications where both disposability and portability are of extreme importance.

Mechanical characterization of TiO{sub 2} nanofibers produced by different electrospinning techniques

Energy Technology Data Exchange (ETDEWEB)

Vahtrus, Mikk [Institute of Physics, University of Tartu, Ravila 14c, 50412 Tartu (Estonia); Šutka, Andris [Institute of Physics, University of Tartu, Ravila 14c, 50412 Tartu (Estonia); Institute of Silicate Materials, Riga Technical University, P. Valdena 3/7, Riga LV-1048 (Latvia); Institute of Technical Physics, Riga Technical University, P. Valdena 3, Riga LV-1048 (Latvia); Vlassov, Sergei, E-mail: vlassovs@ut.ee [Institute of Solid State Physics, University of Latvia, Kengaraga 8, LV-1063 Riga (Latvia); Šutka, Anna [Institute of Textile Technology and Design, Riga Technical University, Riga LV-1048 (Latvia); Laboratory of Biomass Eco-Efficient Conversation, Latvian State Institute of Wood Chemistry, Dzerbenes Street 27, Riga LV-1006 (Latvia); Polyakov, Boris [Institute of Solid State Physics, University of Latvia, Kengaraga 8, LV-1063 Riga (Latvia); Saar, Rando; Dorogin, Leonid; Lõhmus, Rünno [Institute of Physics, University of Tartu, Ravila 14c, 50412 Tartu (Estonia); Materials Technologies Competence Centre, Riia 185b, 51014 Tartu (Estonia)

2015-02-15

In this work TiO{sub 2} nanofibers produced by needle and needleless electrospinning processes from the same precursor were characterized and compared using Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and in situ SEM nanomechanical testing. Phase composition, morphology, Young's modulus and bending strength values were found. Weibull statistics was used to evaluate and compare uniformity of mechanical properties of nanofibers produced by two different methods. It is shown that both methods yield nanofibers with very similar properties. - Graphical abstract: Display Omitted - Highlights: • TiO{sub 2} nanofibers were produced by needle and needleless electrospinning processes. • Structure was studied by Raman spectroscopy and electron microscopy methods. • Mechanical properties were measured using advanced in situ SEM cantilevered beam bending technique. • Both methods yield nanofibers with very similar properties.

Mechanical characterization of YBCO thin films using nanoindentation and finite element method

Energy Technology Data Exchange (ETDEWEB)

Zhang, Weixing [The Ministry of Education of China (China). Key Lab. of Mechanics on Environment and Disaster in Western China; Lanzhou Univ. (China). College of Civil Engineering and Mechanics

2017-09-15

The mechanical properties of YBCO thin film deposited on SrTiO{sub 3} (100) substrates by magnetron sputtering were determined using Berkovich nanoindentation and scanning electron microscopy. Hardness and elastic modulus were determined via the Oliver-Pharr method from indentation load-depth curves. The hardness values of the YBCO thin film show depth dependence, i. e., indentation size effect, which arose from the surface roughness as detected by scanning electron microscopy. Multiple pop-in events were observed on the loading curves, however, no obvious pop-out takes place during the elastic recovery. In addition, an effective analytical method accommodating the indenter imperfection was proposed and validated against experimental data in terms of elastic modulus, yield stress and friction angle using the Drucker-Prager yield criterion for the YBCO thin film.

Fouling layer characterization and pore-blocking mechanisms in an ...

African Journals Online (AJOL)

Fouling layer characterization and pore-blocking mechanisms in an UF membrane externally coupled to a UASB reactor. ... Regarding pore-blocking mechanisms, standard blocking was the predominant mechanism at the beginning of filtration, coexisting at the end of it with cake filtration. In the first filtration cycle (1 h), after ...

Characterization methods of nuclear fuel materials

International Nuclear Information System (INIS)

Bustillos, O.W.R.; Teixeira, S.R.; Lordello, A.R.; Imakuma, K.; Rodrigues, C.

1980-01-01

In order to organize quality control and quality assurance activities for PWR fuel production, the laboratory of IPEN (Instituto de Pesquisas Energeticas e Nucleares) has developed various chemical and physical methods to be employed for fuel characterization of UO 2 pellets. The techniques developed are the determination of total residual gases by vacuum fusion method, determination of impurity elements by optical spectrography and characterization methods by X-ray diffraction. The development and the implementation of these techniques under the implementation of these techniques under the general scheme of characterization and quality control is the major theme discussed. (E.G.) [pt

Mechanical characterization of sisal reinforced cement mortar

OpenAIRE

R. Fujiyama; F. Darwish; M.V. Pereira

2014-01-01

This work aims at evaluating the mechanical behavior of sisal fiber reinforced cement mortar. The composite material was produced from a mixture of sand, cement, and water. Sisal fibers were added to the mixture in different lengths. Mechanical characterization of both the composite and the plain mortar was carried out using three point bend, compression, and impact tests. Specimens containing notches of different root radii were loaded in three point bending in an effort to determine the eff...

Time-dependent mechanical behavior of human amnion: Macroscopic and microscopic characterization

OpenAIRE

2014-01-01

© 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Characterizing the mechanical response of the human amnion is essential to understand and to eventually prevent premature rupture of fetal membranes. In this study a large set of macroscopic and microscopic mechanical tests have been carried out on fresh unfixed amnion to gain insight into the time dependent material response and the underlying mechanisms. Creep and relaxation responses of amnion were characterized in...

Strategy for identification & characterization of Bartonella henselae with conventional & molecular methods

Directory of Open Access Journals (Sweden)

Kavita Diddi

2013-01-01

Full Text Available Background & objectives: Bartonella henselae is a fastidious gram-negative bacterium usually causing self limiting infections in immunocompetent individuals but often causes potentially life threatening infection, such as bacillary angiomatosis in immunocompromised patients. Both diagnosis of infections and research into molecular mechanisms of pathogenesis have been hindered by lack of appropriate and reliable diagnostic techniques. We undertook this study to standardize methods to characterize B. henselae in clinical samples to diagnose Bartonella infection correctly. Methods: B. henselae ATCC 49882 strain was procured from American type culture collection, USA. This strain was revived and maintained in the laboratory, and identification and characterization of this strain was done by conventional and molecular techniques, which included culture on various media, staining by different methods including electron microscopy, biochemical analysis by conventional methods and API, polymerase chain reaction (PCR for amplification of citrate synthase gene followed by restriction fragment length polymorphism (RFLP. Results: This organism was biochemically inert due to slow growth and generated unique identification code with API. The amplification of the citrate-synthase gene with primers yielded a 381 bp product followed by specific RFLP profile for B. henselae. Interpretation & conclusions: Bartonella is fastidious and fragile organism and should be handled carefully. Extra effort and careful observation are required to isolate and characterize this organism.

MEMS-based platforms for mechanical manipulation and characterization of cells

Science.gov (United States)

Pan, Peng; Wang, Wenhui; Ru, Changhai; Sun, Yu; Liu, Xinyu

2017-12-01

Mechanical manipulation and characterization of single cells are important experimental techniques in biological and medical research. Because of the microscale sizes and highly fragile structures of cells, conventional cell manipulation and characterization techniques are not accurate and/or efficient enough or even cannot meet the more and more demanding needs in different types of cell-based studies. To this end, novel microelectromechanical systems (MEMS)-based technologies have been developed to improve the accuracy, efficiency, and consistency of various cell manipulation and characterization tasks, and enable new types of cell research. This article summarizes existing MEMS-based platforms developed for cell mechanical manipulation and characterization, highlights their specific design considerations making them suitable for their designated tasks, and discuss their advantages and limitations. In closing, an outlook into future trends is also provided.

High-throughput characterization methods for lithium batteries

Directory of Open Access Journals (Sweden)

Yingchun Lyu

2017-09-01

Full Text Available The development of high-performance lithium ion batteries requires the discovery of new materials and the optimization of key components. By contrast with traditional one-by-one method, high-throughput method can synthesize and characterize a large number of compositionally varying samples, which is able to accelerate the pace of discovery, development and optimization process of materials. Because of rapid progress in thin film and automatic control technologies, thousands of compounds with different compositions could be synthesized rapidly right now, even in a single experiment. However, the lack of rapid or combinatorial characterization technologies to match with high-throughput synthesis methods, limit the application of high-throughput technology. Here, we review a series of representative high-throughput characterization methods used in lithium batteries, including high-throughput structural and electrochemical characterization methods and rapid measuring technologies based on synchrotron light sources.

A miniaturized test method for the mechanical characterization of structural materials for fusion reactors

International Nuclear Information System (INIS)

Gondi, P.; Montanari, R.; Sili, A.

1996-01-01

This work deals with a non-destructive method for mechanical tests which is based on the indentation of materials at a constant rate by means of a cylinder with a small radius and penetrating flat surface. The load versus penetration depth curves obtained using this method have shown correspondences with those of tensile tests and have given indications about the mechanical properties on a reduced scale. In this work penetration tests have been carried out on various kinds of Cr martensitic steels (MANET-2, BATMAN and modified F82H) which are of interest for first wall and structural applications in future fusion reactors. The load versus penetration depth curves have been examined with reference to data obtained in tensile tests and to microhardness measurements. Penetration tests have been performed at various temperature (from -180 to 100 C). Conclusions, which can be drawn for the ductile to brittle transition, are discussed for MANET-2 steel. Preliminary results obtained on BATMAN and modified F82H steels are reported. The characteristics of the indenter imprints have been studied by scanning electron microscopy. (orig.)

Characterizing the Mechanical Properties of Running-Specific Prostheses

Science.gov (United States)

Beck, Owen N.; Taboga, Paolo; Grabowski, Alena M.

2016-01-01

The mechanical stiffness of running-specific prostheses likely affects the functional abilities of athletes with leg amputations. However, each prosthetic manufacturer recommends prostheses based on subjective stiffness categories rather than performance based metrics. The actual mechanical stiffness values of running-specific prostheses (i.e. kN/m) are unknown. Consequently, we sought to characterize and disseminate the stiffness values of running-specific prostheses so that researchers, clinicians, and athletes can objectively evaluate prosthetic function. We characterized the stiffness values of 55 running-specific prostheses across various models, stiffness categories, and heights using forces and angles representative of those measured from athletes with transtibial amputations during running. Characterizing prosthetic force-displacement profiles with a 2nd degree polynomial explained 4.4% more of the variance than a linear function (prunning 3 m/s and 6 m/s (10°-25°) compared to neutral (0°) (pRunning-specific prostheses should be tested under the demands of the respective activity in order to derive relevant characterizations of stiffness and function. In all, our results indicate that when athletes with leg amputations alter prosthetic model, height, and/or sagittal plane alignment, their prosthetic stiffness profiles also change; therefore variations in comfort, performance, etc. may be indirectly due to altered stiffness. PMID:27973573

A method for quantifying mechanical properties of tissue following viral infection.

Directory of Open Access Journals (Sweden)

Vy Lam

Full Text Available Viral infection and replication involves the reorganization of the actin network within the host cell. Actin plays a central role in the mechanical properties of cells. We have demonstrated a method to quantify changes in mechanical properties of fabricated model three-dimensional (3D connective tissue following viral infection. Using this method, we have characterized the impact of infection by the human herpesvirus, cytomegalovirus (HCMV. HCMV is a member of the herpesvirus family and infects a variety of cell types including fibroblasts. In the body, fibroblasts are necessary for maintaining connective tissue and function by creating mechanical force. Using this 3D connective tissue model, we observed that infection disrupted the cell's ability to generate force and reduced the cumulative contractile force of the tissue. The addition of HCMV viral particles in the absence of both viral gene expression and DNA replication was sufficient to disrupt tissue function. We observed that alterations of the mechanical properties are, in part, due to a disruption of the underlying complex actin microfilament network established by the embedded fibroblasts. Finally, we were able to prevent HCMV-mediated disruption of tissue function by the addition of human immune globulin against HCMV. This study demonstrates a method to quantify the impact of viral infection on mechanical properties which are not evident using conventional cell culture systems.

Methods of celestial mechanics

CERN Document Server

Brouwer, Dirk

2013-01-01

Methods of Celestial Mechanics provides a comprehensive background of celestial mechanics for practical applications. Celestial mechanics is the branch of astronomy that is devoted to the motions of celestial bodies. This book is composed of 17 chapters, and begins with the concept of elliptic motion and its expansion. The subsequent chapters are devoted to other aspects of celestial mechanics, including gravity, numerical integration of orbit, stellar aberration, lunar theory, and celestial coordinates. Considerable chapters explore the principles and application of various mathematical metho

Ultrasonic assisted production of starch nanoparticles: Structural characterization and mechanism of disintegration.

Science.gov (United States)

Boufi, Sami; Bel Haaj, Sihem; Magnin, Albert; Pignon, Frédéric; Impéror-Clerc, Marianne; Mortha, Gérard

2018-03-01

In this paper, the disintegration of starch (waxy and standard starch) granules into nanosized particles under the sole effect of high power ultrasonication treatment in water/isopropanol is investigated, by using wide methods of analysis. The present work aims at a fully characterization of the starch nanoparticles produced by ultrasonication, in terms of size, morphology and structural properties, and the proposition of a possible mechanism explaining the top-down generation of starch nanoparticles (SNPs) via high intensity ultrasonication. Dynamic light scattering measurements have indicated a leveling of the particle size to about 40nm after 75min of ultrasonication. The WAXD, DSC and Raman have revealed the amorphous character of the SNPs. FE-SEM. AFM observations have confirmed the size measured by DLS and suggested that SNPs exhibited 2D morphology of platelet-like shapes. This morphology is further supported by SAXS. On the basis of data collected from the different characterization techniques, a possible mechanism explaining the disintegration process of starch granules into NPs is proposed. Copyright © 2017 Elsevier B.V. All rights reserved.

Parametric and mechanical characterization of linear low density ...

Indian Academy of Sciences (India)

characterization of the material is equally important in relation to quality and relia- ... be moulded as one single part (with no weld lines or joints), eliminating high .... mechanical analysis of three powders viz. polyethylene, polypropylene and ...

Characterizing time-dependent mechanics in metallic MEMS

Directory of Open Access Journals (Sweden)

Geers M.G.D.

2010-06-01

Full Text Available Experiments for characterization of time-dependent material properties in free-standing metallic microelectromechanical system (MEMS pose challenges: e.g. fabrication and handling (sub-μm sized specimens, control and measurement of sub-μN loads and sub-μm displacements over long periods and various temperatures [1]. A variety of experimental setups have been reported each having their pros and cons. One example is a micro-tensile tester with an ingenious electro-static specimen gripping system [2] aiding simple specimen design giving good results at μN and sub-μm levels, but without in-situ full-field observations. Other progressive examples assimilate the specimen, MEMS actuators and load cells on a single chip [3,4] yielding significant results at nN and nm levels with in-situ TEM/SEM observability, though not without complications: complex load actuator/sensor calibration per chip, measures to reduce fabrication failure and unfeasible cofabrication on wafers with commercial metallic MEMS. This work aims to overcome these drawbacks by developing experimental methods with high sensitivity, precision and in-situ full-field observation capabilities. Moreover, these should be applicable to simple free-standing metallic MEMS that can be co-fabricated with commercial devices. These methods will then serve in systematic studies into size-effects in time-dependent material properties. First a numeric-experimental method is developed. It characterizes bending deformation of onwafer μm-sized aluminum cantilevers. A specially designed micro-clamp is used to mechanically apply a constant precise deflection of the beam (zres <50 nm for a prolonged period, see fig. 1. After this period, the deflection by the micro-clamp is removed. Full-field height maps with the ensuing deformation are measured over time with confocal optical profilometry (COP. This yields the tip deflection as function of time with ~3 nm precision, see fig.2. To extract material

Morphological Characterization of Nanofibers: Methods and Application in Practice

Directory of Open Access Journals (Sweden)

Jakub Širc

2012-01-01

Full Text Available Biomedical applications such as wound dressing for skin regeneration, stem cell transplantation, or drug delivery require special demands on the three-dimensional porous scaffolds. Besides the biocompatibility and mechanical properties, the morphology is the most important attribute of the scaffold. Specific surface area, volume, and size of the pores have considerable effect on cell adhesion, growth, and proliferation. In the case of incorporated biologically active substances, their release is also influenced by the internal structure of nanofibers. Although many scientific papers are focused on the preparation of nanofibers and evaluation of biological tests, the morphological characterization was described just briefly as service methods. The aim of this paper is to summarize the methods applicable for morphological characterization of nanofibers and supplement it by the results of our research. Needleless electrospinning technique was used to prepare nanofibers from polylactide, poly(ε-caprolactone, gelatin, and polyamide. Scanning electron microscopy was used to evaluate the fiber diameters and to reveal eventual artifacts in the nanofibrous structure. Nitrogen adsorption/desorption measurements were employed to measure the specific surface areas. Mercury porosimetry was used to determine total porosities and compare pore size distributions of the prepared samples.

Characterization of cell mechanical properties by computational modeling of parallel plate compression.

Science.gov (United States)

McGarry, J P

2009-11-01

A substantial body of work has been reported in which the mechanical properties of adherent cells were characterized using compression testing in tandem with computational modeling. However, a number of important issues remain to be addressed. In the current study, using computational analyses, the effect of cell compressibility on the force required to deform spread cells is investigated and the possibility that stiffening of the cell cytoplasm occurs during spreading is examined based on published experimental compression test data. The effect of viscoelasticity on cell compression is considered and difficulties in performing a complete characterization of the viscoelastic properties of a cell nucleus and cytoplasm by this method are highlighted. Finally, a non-linear force-deformation response is simulated using differing linear viscoelastic properties for the cell nucleus and the cell cytoplasm.

Microstructural and mechanical characterization of injection molded 718 superalloy powders

Energy Technology Data Exchange (ETDEWEB)

Özgün, Özgür [Bingol University, Faculty of Engineering and Architecture, Mechanical Eng. Dep., 12000 Bingol (Turkey); Gülsoy, H. Özkan, E-mail: ogulsoy@marmara.edu.tr [Marmara University, Technology Faculty, Metallurgy and Materials Eng. Dep., 34722 Istanbul (Turkey); Yılmaz, Ramazan [Sakarya University, Technology Faculty, Metallurgy and Materials Eng. Dep., 54187 Sakarya (Turkey); Fındık, Fehim [Sakarya University, Technology Faculty, Metallurgy and Materials Eng. Dep., 54187 Sakarya (Turkey) and International University of Sarajevo, Faculty of Engineering and Natural Sciences, Department of Mechanical Engineering, 71000 Sarajevo, Bosnia and Herzegovina (Bosnia and Herzegowina)

2013-11-05

Highlights: •Microstructural and mechanical properties of injection molded Nickel 718 superalloy were studied. •The maximum sintered density achieved this study was 97.3% at 1290 °C for 3 hours. •Tensile strength of 1022 MPa and elongation of 5.3% were achieved for sintered-heat treated samples. -- Abstract: This study concerns with the determination of optimum production parameters for injection molding 718 superalloy parts. And at the same time, microstructural and mechanical characterization of these produced parts was also carried out. At the initial stage, 718 superalloy powders were mixed with a multi-component binder system for preparing feedstock. Then the prepared feedstock was granulated and shaped by injection molding. Following this operation, the shaped samples were subjected to the debinding process. These samples were sintered at different temperatures for various times. Samples sintered under the condition that gave way to the highest relative density (3 h at 1290 °C) were solution treated and aged respectively. Sintered, solution treated and aged samples were separately subjected to microstructural and mechanical characterization. Microstructural characterization operations such as X-ray diffraction, optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and elemental analysis showed that using polymeric binder system led to plentiful carbide precipitates to be occurred in the injection molded samples. It is also observed that the volume fractions of the intermetallic phases (γ′ and γ″) obtained by aging treatment were decreased due to the plentiful carbide precipitation in the samples. Mechanical characterization was performed by hardness measurements and tensile tests.

Mechanical modeling and characterization of meniscus tissue using flat punch indentation and inverse finite element method.

Science.gov (United States)

Seyfi, Behzad; Fatouraee, Nasser; Imeni, Milad

2018-01-01

In this paper, to characterize the mechanical properties of meniscus by considering its local microstructure, a novel nonlinear poroviscoelastic Finite Element (FE) model has been developed. To obtain the mechanical response of meniscus, indentation experiments were performed on bovine meniscus samples. The ramp-relaxation test scenario with different depths and preloads was designed to capture the mechanical characteristics of the tissue in different regions of the medial and lateral menisci. Thereafter, a FE simulation was performed considering experimental conditions. Constitutive parameters were optimized by solving a FE-based inverse problem using the heuristic Simulated Annealing (SA) optimization algorithm. These parameters were ranged according to previously reported data to improve the optimization procedure. Based on the results, the mechanical properties of meniscus were highly influenced by both superficial and main layers. At low indentation depths, a high percentage relaxation (p < 0.01) with a high relaxation rate (p < 0.05) was obtained, due to the poroelastic and viscoelastic nature of the superficial layer. Increasing both penetration depth and preload level involved the main layer response and caused alterations in hyperelastic and viscoelastic parameters of the tissue, such that for both layers, the shear modulus was increased (p < 0.01) while the rate and percentage of relaxation were decreased (p < 0.01). Results reflect that, shear modulus of the main layer in anterior region is higher than central and posterior sites in medial meniscus. In contrast, in lateral meniscus, posterior side is stiffer than central and anterior sides. Copyright © 2017 Elsevier Ltd. All rights reserved.

On the Use of Accelerated Test Methods for Characterization of Advanced Composite Materials

Science.gov (United States)

Gates, Thomas S.

2003-01-01

A rational approach to the problem of accelerated testing for material characterization of advanced polymer matrix composites is discussed. The experimental and analytical methods provided should be viewed as a set of tools useful in the screening of material systems for long-term engineering properties in aerospace applications. Consideration is given to long-term exposure in extreme environments that include elevated temperature, reduced temperature, moisture, oxygen, and mechanical load. Analytical formulations useful for predictive models that are based on the principles of time-based superposition are presented. The need for reproducible mechanisms, indicator properties, and real-time data are outlined as well as the methodologies for determining specific aging mechanisms.

Mechanical characterization of cemented carbide WC-6Co (%wt) manufactured by SPS (Spark Plasma Sintering

International Nuclear Information System (INIS)

Boidi, G.; Tertuliano, A.J.; Machado, I.F.

2016-01-01

This work aimed to manufacture cemented carbide (WC-6%wtCo) obtained by SPS (Spark Plasma Sintering) process and to carry out the mechanical characterization by hardness and fracture toughness. The material was consolidated at 1100 deg C for different holding times (1 min, 5 min, 10 min), in order to evaluate the densification. A reference sample was also used to be compared to SPS. Optical and scanning electron microscopy were carried out to characterize the microstructural features of the samples and mechanical properties were obtained by hardness measurements (micro and macro) and instrumented indentation. The fracture toughness was calculated with the method of Palmqvist. Best results were found in the material sintered by SPS for 10 minutes of holding time, in which 97% of relative density and about 1600 HV_1_0 was reached. (author)

Mechanical characterization and constitutive modeling of Mg alloy sheets

International Nuclear Information System (INIS)

Mekonen, M. Nebebe; Steglich, D.; Bohlen, J.; Letzig, D.; Mosler, J.

2012-01-01

Highlights: ► Material characterization of the Mg alloys AZ31 and ZE10 at elevated temperatures. ► Distortion of the yield locus does not depend on the strain rate. ► Novel constitutive model suitable for the analysis of sheet forming of magnesium. ► Strain-dependent r-values are included within the model. ► The model is thermodynamically consistent and accounts for distortional hardening. - Abstract: In this paper, an experimental mechanical characterization of the magnesium alloys ZE10 and AZ31 is performed and a suitable constitutive model is established. The mechanical characterization is based on uniaxial tensile tests. In order to avoid poor formability at room temperature, the tests were conducted at elevated temperature (200 °C). The uniaxial tensile tests reveal sufficient ductility allowing sheet forming processes at this temperature. The differences in yield stresses and plastic strain ratios (r-values) confirm the anisotropic response of the materials under study. The constitutive model is established so that the characteristic mechanical features observed in magnesium alloys such as anisotropy and compression-tension asymmetry can be accommodated. This model is thermodynamically consistent, incorporates rate effect, is formulated based on finite strain plasticity theory and is applicable in sheet forming simulations of magnesium alloys. More precisely, a model originally proposed by Cazacu and Barlat in 2004 and later modified to account for the evolution of the material anisotropy is rewritten in a thermodynamically consistent framework. The calibrated constitutive model is shown to capture the characteristic mechanical features observed in magnesium alloy sheets.

Acoustic Emission Technique Applied in Textiles Mechanical Characterization

Directory of Open Access Journals (Sweden)

Rios-Soberanis Carlos Rolando

2017-01-01

Full Text Available The common textile architecture/geometry are woven, braided, knitted, stitch boded, and Z-pinned. Fibres in textile form exhibit good out-of-plane properties and good fatigue and impact resistance, additionally, they have better dimensional stability and conformability. Besides the nature of the textile, the architecture has a great role in the mechanical behaviour and mechanisms of damage in textiles, therefore damage mechanisms and mechanical performance in structural applications textiles have been a major concern. Mechanical damage occurs to a large extent during the service lifetime consequently it is vital to understand the material mechanical behaviour by identifying its mechanisms of failure such as onset of damage, crack generation and propagation. In this work, textiles of different architecture were used to manufacture epoxy based composites in order to study failure events under tensile load by using acoustic emission technique which is a powerful characterization tool due to its link between AE data and fracture mechanics, which makes this relation a very useful from the engineering point of view.

Mechanical characterization of composite materials by optical techniques: A review

Science.gov (United States)

Bruno, Luigi

2018-05-01

The present review provides an overview of work published in recent years dealing with the mechanical characterization of composite materials performed by optical techniques. The paper emphasizes the strengths derived from the employment of full-field methods when the strain field of an anisotropic material must be evaluated. This is framed in contrast to the use of conventional measurement techniques, which provide single values of the measured quantities unable to offer thorough descriptions of deformation distribution. The review outlines the intensity and articulation of work in this research field to date and its ongoing importance not only in the academy, but also in industrial sectors where composite materials represent a strategic resource for development.

Temperature buffer test. Hydro-mechanical and chemical/ mineralogical characterizations

International Nuclear Information System (INIS)

Aakesson, Mattias; Olsson, Siv; Dueck, Ann; Nilsson, Ulf; Karnland, Ola; Kiviranta, Leena; Kumpulainen, Sirpa; Linden, Johan

2012-01-01

The Temperature Buffer Test (TBT) is a joint project between SKB/ANDRA and supported by ENRESA (modeling) and DBE (instrumentation), which aims at improving the understanding and to model the thermo-hydro-mechanical behavior of buffers made of swelling clay submitted to high temperatures (over 100 deg C) during the water saturation process. The test has been carried out in a KBS-3 deposition hole at Aspo HRL. It was installed during the spring of 2003. Two steel heaters (3 m long, 0.6 m diameter) and two buffer arrangements have been investigated: the lower heater was surrounded by rings of compacted Wyoming bentonite only, whereas the upper heater was surrounded by a composite barrier, with a sand shield between the heater and the bentonite. The test was dismantled and sampled during the winter of 2009/2010. This report presents the hydro-mechanical and chemical/mineralogical characterization program which was launched subsequent to the dismantling operation. The main goal has been to investigate if any significant differences could be observed between material from the field experiment and the reference material. The field samples were mainly taken from Ring 4 (located at the mid-section around the lower heater), in which the temperature in the innermost part reached 155 deg C. The following hydro-mechanical properties have been determined for the material (test technique within brackets): hydraulic conductivity (swelling pressure device), swelling pressure (swelling pressure device), unconfined compression strength (mechanical press), shear strength (triaxial cell) and retention properties (jar method). The following chemical/mineralogical properties (methods within brackets) were determined: anion analysis of water leachates (IC), chemical composition (ICP/AES+MS, EGA), cation exchange capacity (CEC, Cu-trien method) and exchangeable cations (exchange with NH4, ICPAES), mineralogical composition (XRD and FTIR), element distribution and microstructure (SEM and

Thermo-mechanical characterization of ceramic pebbles for breeding blanket

Energy Technology Data Exchange (ETDEWEB)

Lo Frano, Rosa, E-mail: rosa.lofrano@ing.unipi.it; Aquaro, Donato; Scaletti, Luca

2016-11-01

Highlights: • Experimental activities to characterize the Li{sub 4}SiO{sub 4}. • Compression tests of pebbles. • Experimental evaluation of thermal conductivity of pebbles bed at different temperatures. • Experimental test with/without compression load. - Abstract: An open issue for fusion power reactor is to design a suitable breeding blanket capable to produce the necessary quantity of the tritium and to transfer the energy of the nuclear fusion reaction to the coolant. The envisaged solution called Helium-Cooled Pebble Bed (HCPB) breeding blanket foresees the use of lithium orthosilicate (Li{sub 4}SiO{sub 4}) or lithium metatitanate (Li{sub 2}TiO{sub 3}) pebble beds. The thermal mechanical properties of the candidate pebble bed materials are presently extensively investigated because they are critical for the feasibility and performances of the numerous conceptual designs which use a solid breeder. This study is aimed at the investigation of mechanical properties of the lithium orthosilicate and at the characterization of the main chemical, physical and thermo-mechanical properties taking into account the production technology. In doing that at the Department of Civil and Industrial Engineering (DICI) of the University of Pisa adequate experiments were carried out. The obtained results may contribute to characterize the material of the pebbles and to optimize the design of the envisaged fusion breeding blankets.

Mechanical characterization of porcine abdominal organs.

Science.gov (United States)

Tamura, Atsutaka; Omori, Kiyoshi; Miki, Kazuo; Lee, Jong B; Yang, King H; King, Albert I

2002-11-01

Typical automotive related abdominal injuries occur due to contact with the rim of the steering wheel, seatbelt and armrest, however, the rate is less than in other body regions. When solid abdominal organs, such as the liver, kidneys and spleen are involved, the injury severity tends to be higher. Although sled and pendulum impact tests have been conducted using cadavers and animals, the mechanical properties and the tissue level injury tolerance of abdominal solid organs are not well characterized. These data are needed in the development of computer models, the improvement of current anthropometric test devices and the enhancement of our understanding of abdominal injury mechanisms. In this study, a series of experimental tests on solid abdominal organs was conducted using porcine liver, kidney and spleen specimens. Additionally, the injury tolerance of the solid organs was deduced from the experimental data.

Overview of the most commonly used methods in allergen characterization

Directory of Open Access Journals (Sweden)

TANJA CIRKOVIC VELICKOVIC

2005-03-01

Full Text Available The characterization of an allergen is a troublesome and difficult process, as it requires both the precise biochemical characterization of a (glycoprotein molecule and the establishment of its susceptibility to IgE antibodies, as they are themain link to histamine release in some hypersensitivity states (type I allergies. As the characterization of an allergen includes molecular weight determination of the allergenic molecule, its structure determination, physicochemical properties, IgE binding properties of the allergen molecule, and its allergenicity, an overal review of which biochemical and immunochemical methods are used in achieving this goal are presented in this paper. The information on the molecular level on the stuctures of allergens indicates that allergens are considerably heterogeneous protein structures, and that there is no particular aminoacid sequence which is responsible for the allergenicity. Therefore, information gained from detailed structural, functional and immunochemical studies of these intriguing molecules, which nowadaysmodulate a variety of pathophysiological conditions, would greatly improve our understanding of the underlying disease mechanisms, and the way to handle them.

Characterization of porosity in support of mechanical property analysis

International Nuclear Information System (INIS)

Price, R.H.; Martin, R.J. III; Boyd, P.J.

1992-01-01

Previous laboratory investigations of tuff have shown that porosity has a dominant, general effect on mechanical properties. As a result, it is very important for the interpretation of mechanical property data that porosity is measured on each sample tested. Porosity alone, however, does not address all of the issues important to mechanical behavior. Variability in size and distribution of pore space produces significantly different mechanical properties. A nondestructive technique for characterizing the internal structure of the sample prior to testing is being developed and the results are being analyzed. The information obtained from this technique can help in both qualitative and quantitative interpretation of test results

Large amplitude oscillatory measurements as mechanical characterization methods for soft elastomers

DEFF Research Database (Denmark)

Skov, Anne Ladegaard

2012-01-01

oscillating elongation (LAOE)1 and planar elongation2, 3 make the ideal set of experiments to evaluate the mechanical performance of DEAPs. We evaluate the mechanical performance of several soft elastomers applicable for DEAP purposes such as poly(propyleneoxide) (PPO) networks3, 4 and traditional unfilled...

Estimation of mechanical properties of nanomaterials using artificial intelligence methods

Science.gov (United States)

Vijayaraghavan, V.; Garg, A.; Wong, C. H.; Tai, K.

2014-09-01

Computational modeling tools such as molecular dynamics (MD), ab initio, finite element modeling or continuum mechanics models have been extensively applied to study the properties of carbon nanotubes (CNTs) based on given input variables such as temperature, geometry and defects. Artificial intelligence techniques can be used to further complement the application of numerical methods in characterizing the properties of CNTs. In this paper, we have introduced the application of multi-gene genetic programming (MGGP) and support vector regression to formulate the mathematical relationship between the compressive strength of CNTs and input variables such as temperature and diameter. The predictions of compressive strength of CNTs made by these models are compared to those generated using MD simulations. The results indicate that MGGP method can be deployed as a powerful method for predicting the compressive strength of the carbon nanotubes.

Semi-automated potentiometric titration method for uranium characterization

Energy Technology Data Exchange (ETDEWEB)

Cristiano, B.F.G., E-mail: barbara@ird.gov.br [Comissao Nacional de Energia Nuclear (CNEN), Instituto de Radioprotecao e Dosimetria (IRD), Avenida Salvador Allende s/n Recreio dos Bandeirantes, PO Box 37750, Rio de Janeiro, 22780-160 RJ (Brazil); Delgado, J.U.; Silva, J.W.S. da; Barros, P.D. de; Araujo, R.M.S. de [Comissao Nacional de Energia Nuclear (CNEN), Instituto de Radioprotecao e Dosimetria (IRD), Avenida Salvador Allende s/n Recreio dos Bandeirantes, PO Box 37750, Rio de Janeiro, 22780-160 RJ (Brazil); Lopes, R.T. [Programa de Engenharia Nuclear (PEN/COPPE), Universidade Federal do Rio de Janeiro (UFRJ), Ilha do Fundao, PO Box 68509, Rio de Janeiro, 21945-970 RJ (Brazil)

2012-07-15

The manual version of the potentiometric titration method has been used for certification and characterization of uranium compounds. In order to reduce the analysis time and the influence of the analyst, a semi-automatic version of the method was developed in the Brazilian Nuclear Energy Commission. The method was applied with traceability assured by using a potassium dichromate primary standard. The combined standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization. - Highlights: Black-Right-Pointing-Pointer We developed a semi-automatic version of potentiometric titration method. Black-Right-Pointing-Pointer The method is used for certification and characterization of uranium compounds. Black-Right-Pointing-Pointer The traceability of the method was assured by a K{sub 2}Cr{sub 2}O{sub 7} primary standard. Black-Right-Pointing-Pointer The results of U{sub 3}O{sub 8} reference material analyzed was consistent with certified value. Black-Right-Pointing-Pointer The uncertainty obtained, near 0.01%, is useful for characterization purposes.

Characterization of Mechanical Properties of Tissue Scaffolds by Phase Contrast Imaging and Finite Element Modeling.

Science.gov (United States)

Bawolin, Nahshon K; Dolovich, Allan T; Chen, Daniel X B; Zhang, Chris W J

2015-08-01

In tissue engineering, the cell and scaffold approach has shown promise as a treatment to regenerate diseased and/or damaged tissue. In this treatment, an artificial construct (scaffold) is seeded with cells, which organize and proliferate into new tissue. The scaffold itself biodegrades with time, leaving behind only newly formed tissue. The degradation qualities of the scaffold are critical during the treatment period, since the change in the mechanical properties of the scaffold with time can influence cell behavior. To observe in time the scaffold's mechanical properties, a straightforward method is to deform the scaffold and then characterize scaffold deflection accordingly. However, experimentally observing the scaffold deflection is challenging. This paper presents a novel study on characterization of mechanical properties of scaffolds by phase contrast imaging and finite element modeling, which specifically includes scaffold fabrication, scaffold imaging, image analysis, and finite elements (FEs) modeling of the scaffold mechanical properties. The innovation of the work rests on the use of in-line phase contrast X-ray imaging at 20 KeV to characterize tissue scaffold deformation caused by ultrasound radiation forces and the use of the Fourier transform to identify movement. Once deformation has been determined experimentally, it is then compared with the predictions given by the forward solution of a finite element model. A consideration of the number of separate loading conditions necessary to uniquely identify the material properties of transversely isotropic and fully orthotropic scaffolds is also presented, along with the use of an FE as a form of regularization.

Food powders flowability characterization: theory, methods, and applications.

Science.gov (United States)

Juliano, Pablo; Barbosa-Cánovas, Gustavo V

2010-01-01

Characterization of food powders flowability is required for predicting powder flow from hoppers in small-scale systems such as vending machines or at the industrial scale from storage silos or bins dispensing into powder mixing systems or packaging machines. This review covers conventional and new methods used to measure flowability in food powders. The method developed by Jenike (1964) for determining hopper outlet diameter and hopper angle has become a standard for the design of bins and is regarded as a standard method to characterize flowability. Moreover, there are a number of shear cells that can be used to determine failure properties defined by Jenike's theory. Other classic methods (compression, angle of repose) and nonconventional methods (Hall flowmeter, Johanson Indicizer, Hosokawa powder tester, tensile strength tester, powder rheometer), used mainly for the characterization of food powder cohesiveness, are described. The effect of some factors preventing flow, such as water content, temperature, time consolidation, particle composition and size distribution, is summarized for the characterization of specific food powders with conventional and other methods. Whereas time-consuming standard methods established for hopper design provide flow properties, there is yet little comparative evidence demonstrating that other rapid methods may provide similar flow prediction.

Computational methods for 2D materials: discovery, property characterization, and application design.

Science.gov (United States)

Paul, J T; Singh, A K; Dong, Z; Zhuang, H; Revard, B C; Rijal, B; Ashton, M; Linscheid, A; Blonsky, M; Gluhovic, D; Guo, J; Hennig, R G

2017-11-29

The discovery of two-dimensional (2D) materials comes at a time when computational methods are mature and can predict novel 2D materials, characterize their properties, and guide the design of 2D materials for applications. This article reviews the recent progress in computational approaches for 2D materials research. We discuss the computational techniques and provide an overview of the ongoing research in the field. We begin with an overview of known 2D materials, common computational methods, and available cyber infrastructures. We then move onto the discovery of novel 2D materials, discussing the stability criteria for 2D materials, computational methods for structure prediction, and interactions of monolayers with electrochemical and gaseous environments. Next, we describe the computational characterization of the 2D materials' electronic, optical, magnetic, and superconducting properties and the response of the properties under applied mechanical strain and electrical fields. From there, we move on to discuss the structure and properties of defects in 2D materials, and describe methods for 2D materials device simulations. We conclude by providing an outlook on the needs and challenges for future developments in the field of computational research for 2D materials.

An Optical Method for the In-Vivo Characterization of the Biomechanical Response of the Right Ventricle.

Science.gov (United States)

Soltani, A; Lahti, J; Järvelä, K; Curtze, S; Laurikka, J; Hokka, M; Kuokkala, V-T

2018-05-01

The intraoperative in-vivo mechanical function of the left ventricle has been studied thoroughly using echocardiography in the past. However, due to technical and anatomical issues, the ultrasound technology cannot easily be focused on the right side of the heart during open-heart surgery, and the function of the right ventricle during the intervention remains largely unexplored. We used optical imaging and digital image correlation for the characterization of the right ventricle motion and deformation during open-heart surgery. This work is a pilot study focusing on one patient only with the aim of establishing the framework for long term research. These experiments show that optical imaging and the analysis of the images can be used to obtain similar parameters, and partly at higher accuracy, for describing the mechanical functioning of the heart as the ultrasound technology. This work describes the optical imaging based method to characterize the mechanical response of the heart in-vivo, and offers new insight into the mechanical function of the right ventricle.

Mechanical characterization and modeling of SiCF/SiC composite tubes

International Nuclear Information System (INIS)

Rohmer, E.

2013-01-01

This work is part of the development of the 4. generation of nuclear reactors. It relates more precisely to the composite portion of the sandwich type tubular cladding considered by the CEA for RNR-NA/Gaz type reactors. The texture is formed by a braiding technique and the study focuses on interlocks braided composite. These relatively new structures require extensive mechanical characterization. Two experimental protocols were developed to conduct tensile and internal pressure tests on tubes. Three different textures have been characterized. In addition, a multi-scale model was developed to connect the microstructure of the tube to its mechanical properties. This model is validated for the elastic behavior of a characterized texture. A first approach to the damage in the structure is proposed and a possible improved protocol is discussed. (author) [fr

Recent characterization of steel by surface analysis methods

International Nuclear Information System (INIS)

Suzuki, Shigeru

1996-01-01

Surface analysis methods, such as Auger electron spectroscopy, X-ray photoelectron spectroscopy, secondary ion mass spectrometry, glow discharge optical emission spectrometry and so on, have become indispensable to characterize surface and interface of many kinds of steel. Although a number of studies on characterization of steel by these methods have been carried out, several problems still remain in quantification and depth profiling. Nevertheless, the methods have provided essential information on the concentration and chemical state of elements at the surface and interface. Recent results on characterization of oxide layers, coated films, etc. on the surface of steel are reviewed here. (author). 99 refs

A high throughput array microscope for the mechanical characterization of biomaterials

Science.gov (United States)

Cribb, Jeremy; Osborne, Lukas D.; Hsiao, Joe Ping-Lin; Vicci, Leandra; Meshram, Alok; O'Brien, E. Tim; Spero, Richard Chasen; Taylor, Russell; Superfine, Richard

2015-02-01

In the last decade, the emergence of high throughput screening has enabled the development of novel drug therapies and elucidated many complex cellular processes. Concurrently, the mechanobiology community has developed tools and methods to show that the dysregulation of biophysical properties and the biochemical mechanisms controlling those properties contribute significantly to many human diseases. Despite these advances, a complete understanding of the connection between biomechanics and disease will require advances in instrumentation that enable parallelized, high throughput assays capable of probing complex signaling pathways, studying biology in physiologically relevant conditions, and capturing specimen and mechanical heterogeneity. Traditional biophysical instruments are unable to meet this need. To address the challenge of large-scale, parallelized biophysical measurements, we have developed an automated array high-throughput microscope system that utilizes passive microbead diffusion to characterize mechanical properties of biomaterials. The instrument is capable of acquiring data on twelve-channels simultaneously, where each channel in the system can independently drive two-channel fluorescence imaging at up to 50 frames per second. We employ this system to measure the concentration-dependent apparent viscosity of hyaluronan, an essential polymer found in connective tissue and whose expression has been implicated in cancer progression.

Physical-mechanical characterization of hydroxyapatite-titanium oxide composites made by the polymeric sponge method; Caracterizacao fisico-mecanica de compositos porosos de hidroxiapatita-titania confeccionados pelo metodo da esponja polimerica

Energy Technology Data Exchange (ETDEWEB)

Galdino, A.G.S.; Zavaglia, C.A.C. [Universidade Estadual de Campinas (FEM/UNICAMP), SP (Brazil)

2011-07-01

Bioceramics have been used as bone reconstruction materials since last decades, where hydroxyapatite is one of the most used for this purpose. However, hydroxyapatite's mechanical strength is not so high when compared to other bioceramics. This work aimed on characterizing physically and mechanically composites of HA-TiO{sub 2}. Samples were made by the polymeric sponge method with 70% - 30% wt., 60% - 40% wt. and 50% - 50% wt. of HA - TiO{sub 2}, calcined at 550 deg C for sponge burning and sintered at 1250 deg C, 1300 deg C and 1350 deg C. Samples were submitted to mechanical essays of compression and Hardness Vickers and to physical essays of water absorption, apparent density, burning linear retraction and apparent density. Results showed relatively better than those of pure hydroxyapatite and they are in accordance with the literature. (author)

Mechanical Characterization of Rigid Polyurethane Foams

Energy Technology Data Exchange (ETDEWEB)

Lu, Wei-Yang [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Mechanics of Materials

2014-12-01

Foam materials are used to protect sensitive components from impact loading. In order to predict and simulate the foam performance under various loading conditions, a validated foam model is needed and the mechanical properties of foams need to be characterized. Uniaxial compression and tension tests were conducted for different densities of foams under various temperatures and loading rates. Crush stress, tensile strength, and elastic modulus were obtained. A newly developed confined compression experiment provided data for investigating the foam flow direction. A biaxial tension experiment was also developed to explore the damage surface of a rigid polyurethane foam.

Assessment of the excitelet algorithm for in-situ mechanical characterization of orthotropic structures

Science.gov (United States)

Ostiguy, Pierre-Claude; Quaegebeur, Nicolas; Masson, Patrice

2012-04-01

Damage detection and localization on composites can be impaired by inaccurate knowledge of the mechanical properties of the structure. This paper demonstrates the feasibility of using a chirplet-based correlation technique, called Excitelet, to evaluate the mechanical properties of orthotropic carbon fibre-based composite laminates. The method relies on the identification of an optimal correlation coefficient between measured and simulated dispersed signals measured on a structure using piezoceramic (PZT) transducers. Finite Element Model (FEM) is first conducted to demonstrate the capability of the approach to evaluate the mechanical properties of a composite structure. Experimental validation is then conducted on a unidirectionnal 2.30 mm thick laminate composed of unidirectional plies and a 2.35 mm thick laminate composed of unidirectional plies oriented at [0, 90]4s. Surface bonded PZT transducers were used both for actuation and sensing of guided waves bursts measured at 0° and 90° with respect to upper ply fibre orientation. The characterization is performed at various frequencies below 100 kHz using A0 or S0 modes and comparison with the material properties measured following ASTM standard testing is presented. The results indicate that large correlation coefficients are obtained between the measurements and simulated signals for both A0 and S0 modes when accurate properties are used as inputs for the model. Strategies based on multiple modes correlation are also assessed in order to improve the accuracy of the characterization approach. The results obtained using the proposed approach for the unidirectional plate and most of the results obtained using the proposed approach for the [0, 90]4s laminate are in agreement with the uncertainty associated with ASTM tests results while the proposed method is non destructive and can be performed prior to each imaging processing.

Development and Implementation of an Ultrasonic Method to Characterize Acoustic and Mechanical Fingernail Properties

Science.gov (United States)

Vacarescu, Rares Anthony

The human fingernail is a vital organ used by humans on a daily basis and can provide an immense supply of information based on the biological feedback of the body. By studying the quantitative mechanical and acoustic properties of fingernails, a better understanding of the scarcely-investigated field of ungual research can be explored. Investigating fingernail properties with the use of pulse-echo ultrasound is the aim of this thesis. This thesis involves the application of a developed portable ultrasonic device in a hospital-based data collection and the advancement of ultrasonic methodology to include the calculation of acoustic impedance, density and elasticity. The results of the thesis show that the reflectance method can be utilized to determine fingernail properties with a maximum 17% deviation from literature. Repeatability of measurements fell within a 95% confidence interval. Thus, the ultrasonic reflectance method was validated and may have potential clinical and cosmetic applications.

Application of geophysical methods for fracture characterization

International Nuclear Information System (INIS)

Lee, K.H.; Majer, E.L.; McEvilly, T.V.; California Univ., Berkeley, CA; Morrison, H.F.; California Univ., Berkeley, CA

1990-01-01

One of the most crucial needs in the design and implementation of an underground waste isolation facility is a reliable method for the detection and characterization of fractures in zones away from boreholes or subsurface workings. Geophysical methods may represent a solution to this problem. If fractures represent anomalies in the elastic properties or conductive properties of the rocks, then the seismic and electrical techniques may be useful in detecting and characterizing fracture properties. 7 refs., 3 figs

Oromucosal film preparations: classification and characterization methods.

Science.gov (United States)

Preis, Maren; Woertz, Christina; Kleinebudde, Peter; Breitkreutz, Jörg

2013-09-01

Recently, the regulatory authorities have enlarged the variety of 'oromucosal preparations' by buccal films and orodispersible films. Various film preparations have entered the market and pharmacopoeias. Due to the novelty of the official monographs, no standardized characterization methods and quality specifications are included. This review reports the methods of choice to characterize oromucosal film preparations with respect to biorelevant characterization and quality control. Commonly used dissolution tests for other dosage forms are not transferable for films in all cases. Alternatives and guidance on decision, which methods are favorable for film preparations are discussed. Furthermore, issues about requirements for film dosage forms are reflected. Oromucosal film preparations offer a wide spectrum of opportunities. There are a lot of suggestions in the literature on how to control the quality of these innovative products, but no standardized tests are available. Regulatory authorities need to define the standards and quality requirements more precisely.

Atomistic insight into the catalytic mechanism of glycosyltransferases by combined quantum mechanics/molecular mechanics (QM/MM) methods.

Science.gov (United States)

Tvaroška, Igor

2015-02-11

Glycosyltransferases catalyze the formation of glycosidic bonds by assisting the transfer of a sugar residue from donors to specific acceptor molecules. Although structural and kinetic data have provided insight into mechanistic strategies employed by these enzymes, molecular modeling studies are essential for the understanding of glycosyltransferase catalyzed reactions at the atomistic level. For such modeling, combined quantum mechanics/molecular mechanics (QM/MM) methods have emerged as crucial. These methods allow the modeling of enzymatic reactions by using quantum mechanical methods for the calculation of the electronic structure of the active site models and treating the remaining enzyme environment by faster molecular mechanics methods. Herein, the application of QM/MM methods to glycosyltransferase catalyzed reactions is reviewed, and the insight from modeling of glycosyl transfer into the mechanisms and transition states structures of both inverting and retaining glycosyltransferases are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Novel instrument for characterizing comprehensive physical properties under multi-mechanical loads and multi-physical field coupling conditions

Science.gov (United States)

Liu, Changyi; Zhao, Hongwei; Ma, Zhichao; Qiao, Yuansen; Hong, Kun; Ren, Zhuang; Zhang, Jianhai; Pei, Yongmao; Ren, Luquan

2018-02-01

Functional materials represented by ferromagnetics and ferroelectrics are widely used in advanced sensor and precision actuation due to their special characterization under coupling interactions of complex loads and external physical fields. However, the conventional devices for material characterization can only provide a limited type of loads and physical fields and cannot simulate the actual service conditions of materials. A multi-field coupling instrument for characterization has been designed and implemented to overcome this barrier and measure the comprehensive physical properties under complex service conditions. The testing forms include tension, compression, bending, torsion, and fatigue in mechanical loads, as well as different external physical fields, including electric, magnetic, and thermal fields. In order to offer a variety of information to reveal mechanical damage or deformation forms, a series of measurement methods at the microscale are integrated with the instrument including an indentation unit and in situ microimaging module. Finally, several coupling experiments which cover all the loading and measurement functions of the instrument have been implemented. The results illustrate the functions and characteristics of the instrument and then reveal the variety in mechanical and electromagnetic properties of the piezoelectric transducer ceramic, TbDyFe alloy, and carbon fiber reinforced polymer under coupling conditions.

Detailed characterizations of a Comparative Reactivity Method (CRM) instrument: experiments vs. modelling

Science.gov (United States)

Michoud, V.; Hansen, R. F.; Locoge, N.; Stevens, P. S.; Dusanter, S.

2015-04-01

The Hydroxyl radical (OH) is an important oxidant in the daytime troposphere that controls the lifetime of most trace gases, whose oxidation leads to the formation of harmful secondary pollutants such as ozone (O3) and Secondary Organic Aerosols (SOA). In spite of the importance of OH, uncertainties remain concerning its atmospheric budget and integrated measurements of the total sink of OH can help reducing these uncertainties. In this context, several methods have been developed to measure the first-order loss rate of ambient OH, called total OH reactivity. Among these techniques, the Comparative Reactivity Method (CRM) is promising and has already been widely used in the field and in atmospheric simulation chambers. This technique relies on monitoring competitive OH reactions between a reference molecule (pyrrole) and compounds present in ambient air inside a sampling reactor. However, artefacts and interferences exist for this method and a thorough characterization of the CRM technique is needed. In this study, we present a detailed characterization of a CRM instrument, assessing the corrections that need to be applied on ambient measurements. The main corrections are, in the order of their integration in the data processing: (1) a correction for a change in relative humidity between zero air and ambient air, (2) a correction for the formation of spurious OH when artificially produced HO2 react with NO in the sampling reactor, and (3) a correction for a deviation from pseudo first-order kinetics. The dependences of these artefacts to various measurable parameters, such as the pyrrole-to-OH ratio or the bimolecular reaction rate constants of ambient trace gases with OH are also studied. From these dependences, parameterizations are proposed to correct the OH reactivity measurements from the abovementioned artefacts. A comparison of experimental and simulation results is then discussed. The simulations were performed using a 0-D box model including either (1) a

Characterization of Olive Oil by Ultrasonic and Physico-chemical Methods

Science.gov (United States)

Alouache, B.; Khechena, F. K.; Lecheb, F.; Boutkedjirt, T.

Olive oil excels by its nutritional and medicinal benefits. It can be consumed without any treatment. However, its quality can be altered by inadequate storage conditions or if it is mixed with other kinds of oils. The objective of this work is to demonstrate the ability of ultrasonic methods to characterize and control olive oil quality. By using of a transducer of 2.25 MHz nominal frequency, in pulse echo mode, ultrasonic parameters, such as propagation velocity and attenuation,have been measured for pure olive oil and for its mixtures with sunflower oil at different proportions. Mechanical properties, such as density and viscosity, have also been determined. The results of ultrasonic measurements are consistent with those obtained by physico-chemical methods, such as rancidity degree, acid index, UV specific extinction coefficient and viscosity. They show that the ultrasonic method allows to distinguish between mixtures at different proportions. The study allows concluding that ultrasound techniques can be considered as a useful complement to existing physico-chemical analysis techniques.

Finite elements methods in mechanics

CERN Document Server

Eslami, M Reza

2014-01-01

This book covers all basic areas of mechanical engineering, such as fluid mechanics, heat conduction, beams, and elasticity with detailed derivations for the mass, stiffness, and force matrices. It is especially designed to give physical feeling to the reader for finite element approximation by the introduction of finite elements to the elevation of elastic membrane. A detailed treatment of computer methods with numerical examples are provided. In the fluid mechanics chapter, the conventional and vorticity transport formulations for viscous incompressible fluid flow with discussion on the method of solution are presented. The variational and Galerkin formulations of the heat conduction, beams, and elasticity problems are also discussed in detail. Three computer codes are provided to solve the elastic membrane problem. One of them solves the Poisson’s equation. The second computer program handles the two dimensional elasticity problems, and the third one presents the three dimensional transient heat conducti...

Electro-mechanical characterization of structural supercapacitors

Science.gov (United States)

Gallagher, T.; LaMaster, D.; Ciocanel, C.; Browder, C.

2012-04-01

The paper presents electrical and mechanical properties of structural supercapacitors and discusses limitations associated with the approach taken for the electrical properties evaluation. The structural supercapacitors characterized in this work had the electrodes made of carbon fiber weave, separator made of several cellulose based products, and the solid electrolyte made as PEGDGE based polymer blend. The reported electrical properties include capacitance and leakage resistance; the former was measured using cyclic voltammetry. Mechanical properties have been evaluated thorough tensile and three point bending tests performed on structural supercapacitor coupons. The results indicate that the separator material plays an important role on the electrical as well as mechanical properties of the structural capacitor, and that Celgard 3501 used as separator leads to most benefits for both mechanical and electrical properties. Specific capacitance and leakage resistance as high as 1.4kF/m3 and 380kΩ, respectively, were achieved. Two types of solid polymer electrolytes were used in fabrication, with one leading to higher and more consistent leakage resistance values at the expense of a slight decrease in specific capacitance when compared to the other SPE formulation. The ultimate tensile strength and modulus of elasticity of the developed power storage composite were evaluated at 466MPa and 18.9MPa, respectively. These values are 58% and 69% of the tensile strength and modulus of elasticity values measured for a single layer composite material made with the same type of carbon fiber and with a West System 105 epoxy instead of solid polymer electrolyte.

Characterization of Mechanical Properties and Residual Stress in API 5L X80 Steel Welded Joints

Science.gov (United States)

de Sousa Lins, Amilton; de Souza, Luís Felipe Guimarães; Fonseca, Maria Cindra

2018-01-01

The use of high-strength and low-alloy steels, high design factors and increasingly stringent safety requirements have increased the operating pressure levels and, consequently, the need for further studies to avoid and prevent premature pipe failure. To evaluate the possibility of improving productivity in manual arc welding of this type of steel, this work characterizes the mechanical properties and residual stresses in API 5L X80 steel welded joints using the SMAW and FCAW processes. The residual stresses were analyzed using x-ray diffraction with the sin2 ψ method at the top and root of the welded joints in the longitudinal and transverse directions of the weld bead. The mechanical properties of the welded joints by both processes were characterized in terms of tensile strength, impact toughness and Vickers microhardness in the welded and shot peening conditions. A predominantly compressive residual stress was found, and shot peening increased the tensile strength and impact toughness in both welded joints.

Microstructural and mechanical characterization of biomedical Ti-Nb-Zr(-Ta) alloys

International Nuclear Information System (INIS)

Elias, L.M.; Schneider, S.G.; Schneider, S.; Silva, H.M.; Malvisi, F.

2006-01-01

In recent years there has been a significant development of novel implant alloys based on β-Ti such as Ti-Nb-Zr and Ti-Nb-Zr-Ta alloys systems. The purpose of this work is to provide characterization of Ti-35.3Nb-5.1Ta-7.1Zr and Ti-41.1Nb-7.1Zr alloys, in which Nb will substitute the atomic amount of Ta, with emphasis in the property-microstructure-composition relationships. These alloys are produced from commercially pure materials (Ti, Nb, Zr and Ta) by an arc melting method. All ingots were submitted to sequences of heat treatment (1000 deg. C/2 h - WQ), cold working by swaging procedures and other heat treatment (1000 deg. C/2 h - WQ). Specimens, in as cast and heat-treated condition, were examined by light and scanning electron microscopy (SEM). These results suggested the presence of β- and ω-phases. Mechanical properties were based on tensile and hardness tests. These alloys exhibit a lower modulus than that of conventional Ti alloys and the other mechanical properties are suitable for biomedical applications

Towards a method to characterize temporary groundwater dynamics during droughts

Science.gov (United States)

Heudorfer, Benedikt; Stahl, Kerstin

2016-04-01

In order to improve our understanding of the complex mechanisms involved in the development, propagation and termination of drought events, a major challenge is to grasp the role of groundwater systems. Research on how groundwater responds to meteorological drought events (i.e. short-term climate anomalies) is still limited. Part of the problem is that there is as yet no generic method to characterize the response of different groundwater systems to extreme climate anomalies. In order to explore possibilities for such a methodology, we evaluate two statistical approaches to characterize groundwater dynamics on short time scales by applying them on observed groundwater head data from different pre- and peri-mountainous groundwater systems in humid central Europe (Germany). The first method is based on the coefficient of variation in moving windows of various lengths, the second method is based on streamflow recession characteristics applied on groundwater data. With these methods, the gauges behavior during low head events and its response to precipitation was explored. Findings regarding the behavior of the gauges make it possible to distinguish between gauges with a dominance of cyclic patterns, and gauges with a dominance of patterns on seasonal or event scale (commonly referred to as slow/fast responding gauges, respectively). While some clues on what factors that might control these patterns are present, the specific controls are general unclear for the gauges in this study. However as the key conclusion stands the question if the variety of manifestations of groundwater dynamics, as they occur in real systems, is subsumable with one unique method. Further studies on the topic are in progress.

Simultaneous Contact Sensing and Characterizing of Mechanical and Dynamic Heat Transfer Properties of Porous Polymeric Materials

Directory of Open Access Journals (Sweden)

Bao-guo Yao

2017-10-01

Full Text Available Porous polymeric materials, such as textile fabrics, are elastic and widely used in our daily life for garment and household products. The mechanical and dynamic heat transfer properties of porous polymeric materials, which describe the sensations during the contact process between porous polymeric materials and parts of the human body, such as the hand, primarily influence comfort sensations and aesthetic qualities of clothing. A multi-sensory measurement system and a new method were proposed to simultaneously sense the contact and characterize the mechanical and dynamic heat transfer properties of porous polymeric materials, such as textile fabrics in one instrument, with consideration of the interactions between different aspects of contact feels. The multi-sensory measurement system was developed for simulating the dynamic contact and psychological judgment processes during human hand contact with porous polymeric materials, and measuring the surface smoothness, compression resilience, bending and twisting, and dynamic heat transfer signals simultaneously. The contact sensing principle and the evaluation methods were presented. Twelve typical sample materials with different structural parameters were measured. The results of the experiments and the interpretation of the test results were described. An analysis of the variance and a capacity study were investigated to determine the significance of differences among the test materials and to assess the gage repeatability and reproducibility. A correlation analysis was conducted by comparing the test results of this measurement system with the results of Kawabata Evaluation System (KES in separate instruments. This multi-sensory measurement system provides a new method for simultaneous contact sensing and characterizing of mechanical and dynamic heat transfer properties of porous polymeric materials.

Metrological characterization methods for confocal chromatic line sensors and optical topography sensors

Science.gov (United States)

Seppä, Jeremias; Niemelä, Karri; Lassila, Antti

2018-05-01

The increasing use of chromatic confocal technology for, e.g. fast, in-line optical topography, and measuring thickness, roughness and profiles implies a need for the characterization of various aspects of the sensors. Single-point, line and matrix versions of chromatic confocal technology, encoding depth information into wavelength, have been developed. Of these, line sensors are particularly suitable for in-line process measurement. Metrological characterization and development of practical methods for calibration and checking is needed for new optical methods and devices. Compared to, e.g. tactile methods, optical topography measurement techniques have limitations related to light wavelength and coherence, optical properties of the sample including reflectivity, specularity, roughness and colour, and definition of optical versus mechanical surfaces. In this work, metrological characterization methods for optical line sensors were developed for scale magnification and linearity, sensitivity to sample properties, and dynamic characteristics. An accurate depth scale calibration method using a single prototype groove depth sample was developed for a line sensor and validated with laser-interferometric sample tracking, attaining (sub)micrometre level or better than 0.1% scale accuracy. Furthermore, the effect of different surfaces and materials on the measurement and depth scale was studied, in particular slope angle, specularity and colour. In addition, dynamic performance, noise, lateral scale and resolution were measured using the developed methods. In the case of the LCI1200 sensor used in this study, which has a 11.3 mm  ×  2.8 mm measurement range, the instrument depth scale was found to depend only minimally on sample colour, whereas measuring steeply sloped specular surfaces in the peripheral measurement area, in the worst case, caused a somewhat larger relative sample-dependent change (1%) in scale.

Mechanics of ultrasound elastography

Science.gov (United States)

Li, Guo-Yang

2017-01-01

Ultrasound elastography enables in vivo measurement of the mechanical properties of living soft tissues in a non-destructive and non-invasive manner and has attracted considerable interest for clinical use in recent years. Continuum mechanics plays an essential role in understanding and improving ultrasound-based elastography methods and is the main focus of this review. In particular, the mechanics theories involved in both static and dynamic elastography methods are surveyed. They may help understand the challenges in and opportunities for the practical applications of various ultrasound elastography methods to characterize the linear elastic, viscoelastic, anisotropic elastic and hyperelastic properties of both bulk and thin-walled soft materials, especially the in vivo characterization of biological soft tissues. PMID:28413350

Mechanical characterization tests of the X2-Gen fuel assembly and skeleton

International Nuclear Information System (INIS)

Kim, Hyung Kyu; Yoon, Kyung Ho; Lee, Kang Hee; Kim, Jae Yong; Lee, Young Ho; Kang, Heung Seok

2011-01-01

The KNF (KEPCO Nuclear Fuel) requested mechanical characterization tests of a fuel assembly and a skeleton of the X2-Gen fuel. The tests consisted of the lateral vibration and lateral/axial stiffness, lateral/axial impact and combined deflection tests carried out by using the FAMeCT (Fuel Assembly Mechanical Characterization Tester) in KAERI. The upper and lower core plate simulators were newly designed and manufactured because the fuel geometry of the X2-Gen was different from the KSNP type fuel assembly. In addition to this, the upper carriage was also revised with the LM guide system from the previous two guide rods system. Therefore, the axial and combined deflection tests were soundly executed. Each test was repeated twice to confirm the repeatability. The discrepancy from the repetition was small enough to be neglected. The mechanical characterization tests were accredited with the KOLAS (Korea Laboratory Accreditation Scheme) standard, and the certified test reports (lateral vibration, lateral/axial bending and lateral/axial impact) and the uncertified test report (combined deflection) were issued together with the current test result report

A comprehensive review on self-healing of asphalt materials: Mechanism, model, characterization and enhancement.

Science.gov (United States)

Sun, Daquan; Sun, Guoqiang; Zhu, Xingyi; Guarin, Alvaro; Li, Bin; Dai, Ziwei; Ling, Jianming

2018-05-09

Self-healing has great potential to extend the service life of asphalt pavement, and this capability has been regarded as an important strategy when designing a sustainable infrastructure. This review presents a comprehensive summary of the state-of-the-art investigations concerning the self-healing mechanism, model, characterization and enhancement, ranging from asphalt to asphalt pavement. Firstly, the self-healing phenomenon as a general concept in asphalt materials is analyzed including its definition and the differences among self-healing and some viscoelastic responses. Additionally, the development of self-healing in asphalt pavement design is introduced. Next, four kinds of possible self-healing mechanism and corresponding models are presented. It is pointed out that the continuum thermodynamic model, considering the whole process from damage initiation to healing recovery, can be a promising study field. Further, a set of self-healing multiscale characterization methods from microscale to macroscale as well as computational simulation scale, are summed up. Thereinto, the computational simulation shows great potential in simulating the self-healing behavior of asphalt materials from mechanical and molecular level. Moreover, the factors influencing self-healing capability are discussed, but the action mechanisms of some factors remain unclear and need to be investigated. Finally, two extrinsic self-healing technologies, induction heating and capsule healing, are recommended as preventive maintenance applications in asphalt pavement. In future, more effective energy-based healing systems or novel material-based healing systems are expected to be developed towards designing sustainable long-life asphalt pavement. Copyright © 2017 Elsevier B.V. All rights reserved.

Characterization and modelling of the mechanical properties of mineral wool

DEFF Research Database (Denmark)

Chapelle, Lucie

2016-01-01

and as a consequence focus on the mechanical properties of mineral wool has intensified. Also understanding the deformation mechanisms during compression of low density mineral wool is crucial since better thickness recovery after compression will result in significant savings on transport costs. The mechanical...... properties of mineral wool relate closely to the arrangement and characteristics of the fibres inside the material. Because of the complex architecture of mineral wool, the characterization and the understanding of the mechanism of deformations require a new methodology. In this PhD thesis, a methodology...... of the structure on mechanical properties can be explored. The size of the representative volume elements for the prediction of the elastic properties is determined for two types of applied boundary conditions. For sufficiently large volumes, the predicted elastic properties are consistent with results from...

Method for determining damping properties of materials using a suspended mechanical oscillator

Science.gov (United States)

Biscans, S.; Gras, S.; Evans, M.; Fritschel, P.; Pezerat, C.; Picart, P.

2018-06-01

We present a new approach for characterizing the loss factor of materials, using a suspended mechanical oscillator. Compared to more standard techniques, this method offers freedom in terms of the size and shape of the tested samples. Using a finite element model and the vibration measurements, the loss factor is deduced from the oscillator's ring-down. In this way the loss factor can be estimated independently for shear and compression deformation of the sample over a range of frequencies. As a proof of concept, we present measurements for EPO-TEK 353ND epoxy samples.

Characterization of thermoset and thermoplastic polyurethane pads, and molded and non-optimized machined grooving methods for oxide chemical mechanical planarization applications

International Nuclear Information System (INIS)

Sampurno, Yasa; Borucki, Leonard; Zhuang, Yun; Misra, Sudhanshu; Holland, Karey; Boning, Duane; Philipossian, Ara

2009-01-01

This paper systematically studies the effect of pad material, grooving method and grooving pattern on interlayer dielectric chemical mechanical planarization. The tested polishing pads consist of thermoplastic and thermoset polyurethanes synthesized using two different processes. Grooves created using a molding technique are compared with grooves formed by mechanical cutting. The concentric groove design is also compared with the logarithmic positive spiral positive grooving design. Experimental data collected include removal rate, coefficient of friction, shear force variance, pad temperature and dynamic mechanical analyzer measurements. Scanning electron microscope images are used to correlate grooving methods with coefficient of friction and shear force variance measurements. Results show that all of the pads polish wafers in boundary lubrication mode with unique friction coefficient, shear force variance and pad temperature characteristics. Simulations using a two-step removal rate mechanism are performed to estimate the chemical and mechanical rate constants. The analysis indicates that the thermoplastic pad is more mechanically controlled than the thermoset pad and that molded grooving induces a more mechanically controlled process than non-optimized machined grooving

Nondestructive mechanical characterization of developing biological tissues using inflation testing.

Science.gov (United States)

Oomen, P J A; van Kelle, M A J; Oomens, C W J; Bouten, C V C; Loerakker, S

2017-10-01

One of the hallmarks of biological soft tissues is their capacity to grow and remodel in response to changes in their environment. Although it is well-accepted that these processes occur at least partly to maintain a mechanical homeostasis, it remains unclear which mechanical constituent(s) determine(s) mechanical homeostasis. In the current study a nondestructive mechanical test and a two-step inverse analysis method were developed and validated to nondestructively estimate the mechanical properties of biological tissue during tissue culture. Nondestructive mechanical testing was achieved by performing an inflation test on tissues that were cultured inside a bioreactor, while the tissue displacement and thickness were nondestructively measured using ultrasound. The material parameters were estimated by an inverse finite element scheme, which was preceded by an analytical estimation step to rapidly obtain an initial estimate that already approximated the final solution. The efficiency and accuracy of the two-step inverse method was demonstrated on virtual experiments of several material types with known parameters. PDMS samples were used to demonstrate the method's feasibility, where it was shown that the proposed method yielded similar results to tensile testing. Finally, the method was applied to estimate the material properties of tissue-engineered constructs. Via this method, the evolution of mechanical properties during tissue growth and remodeling can now be monitored in a well-controlled system. The outcomes can be used to determine various mechanical constituents and to assess their contribution to mechanical homeostasis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mechanical characterization of zeolite low dielectric constant thin films by nanoindentation

International Nuclear Information System (INIS)

Johnson, Mark; Li Zijian; Wang Junlan; Ya, Yushan

2007-01-01

With semiconductor technologies continuously pushing the miniaturization limits, there is a growing interest in developing novel low dielectric constant materials to replace the traditional dense SiO 2 insulators. In order to survive the multi-level integration process and provide reliable material and structure for the desired integrated circuits (IC) functions, the new low-k materials have to be mechanically strong and stable. Therefore the material selection and mechanical characterization are vital for the successful development of next generation low-k dielectrics. A new class of low-k materials, nanoporous pure-silica zeolite, is prepared in thin films using IC compatible spin coating process and characterized using depth sensing nanoindentation technique. The elastic modulus of the zeolite thin films is found to be significantly higher than that of other low-k materials with similar porosity and dielectric constants. Correlations between the mechanical, microstructural and electrical properties of the thin films are discussed in detail

Mechanical characterization of sisal reinforced cement mortar

Directory of Open Access Journals (Sweden)

R. Fujiyama

2014-01-01

Full Text Available This work aims at evaluating the mechanical behavior of sisal fiber reinforced cement mortar. The composite material was produced from a mixture of sand, cement, and water. Sisal fibers were added to the mixture in different lengths. Mechanical characterization of both the composite and the plain mortar was carried out using three point bend, compression, and impact tests. Specimens containing notches of different root radii were loaded in three point bending in an effort to determine the effect of the fibers on the fracture toughness of the material. The results obtained indicate that, while fiber reinforcement leads to a decrease in compressive strength, J-integral calculations at maximum load for the different notch root radii have indicated, particularly for the case of long fibers, a significant superiority of the reinforced material in comparison with the plain cement mortar, in consistence with the impact test data.

Semi-automated potentiometric titration method for uranium characterization.

Science.gov (United States)

Cristiano, B F G; Delgado, J U; da Silva, J W S; de Barros, P D; de Araújo, R M S; Lopes, R T

2012-07-01

The manual version of the potentiometric titration method has been used for certification and characterization of uranium compounds. In order to reduce the analysis time and the influence of the analyst, a semi-automatic version of the method was developed in the Brazilian Nuclear Energy Commission. The method was applied with traceability assured by using a potassium dichromate primary standard. The combined standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization. Copyright © 2011 Elsevier Ltd. All rights reserved.

Very large scale characterization of graphene mechanical devices using a colorimetry technique.

Science.gov (United States)

Cartamil-Bueno, Santiago Jose; Centeno, Alba; Zurutuza, Amaia; Steeneken, Peter Gerard; van der Zant, Herre Sjoerd Jan; Houri, Samer

2017-06-08

We use a scalable optical technique to characterize more than 21 000 circular nanomechanical devices made of suspended single- and double-layer graphene on cavities with different diameters (D) and depths (g). To maximize the contrast between suspended and broken membranes we used a model for selecting the optimal color filter. The method enables parallel and automatized image processing for yield statistics. We find the survival probability to be correlated with a structural mechanics scaling parameter given by D 4 /g 3 . Moreover, we extract a median adhesion energy of Γ = 0.9 J m -2 between the membrane and the native SiO 2 at the bottom of the cavities.

Structural characterization and mechanical performance of calcium phosphate scaffolds and natural bones: a comparative study.

Science.gov (United States)

Fuentes, Elena; Sáenz de Viteri, Virginia; Igartua, Amaya; Martinetti, Roberta; Dolcini, Laura; Barandika, Gotzone

2010-01-01

The knowledge of the mechanical response of bones and their substitutes is pertinent to numerous medical problems. Understanding the effects of mechanical influence on the body is the first step toward developing innovative treatment and rehabilitation concepts for orthopedic disorders. This was a comparative study of 5 synthetic scaffolds based on porous calcium phosphates and natural bones, with regard to their microstructural, chemical, and mechanical characterizations. The structural and chemical characterizations of the scaffolds were examined by means of X-ray diffraction, scanning electron microscopy, and X-ray spectroscopy analysis. The mechanical characterization of bones and bone graft biomaterials was carried out through compression tests using samples with noncomplex geometry. Analysis of the chemical composition, surface features, porosity, and compressive strength indicates that hydroxyapatite-based materials and trabecular bone have similar properties.

Temperature buffer test. Hydro-mechanical and chemical/ mineralogical characterizations

Energy Technology Data Exchange (ETDEWEB)

Aakesson, Mattias; Olsson, Siv; Dueck, Ann; Nilsson, Ulf; Karnland, Ola [Clay Technology AB, Lund (Sweden); Kiviranta, Leena; Kumpulainen, Sirpa [BandTech Oy, Helsinki (Finland); Linden, Johan [Aabo Akademi, Aabo (Finland)

2012-01-15

The Temperature Buffer Test (TBT) is a joint project between SKB/ANDRA and supported by ENRESA (modeling) and DBE (instrumentation), which aims at improving the understanding and to model the thermo-hydro-mechanical behavior of buffers made of swelling clay submitted to high temperatures (over 100 deg C) during the water saturation process. The test has been carried out in a KBS-3 deposition hole at Aspo HRL. It was installed during the spring of 2003. Two steel heaters (3 m long, 0.6 m diameter) and two buffer arrangements have been investigated: the lower heater was surrounded by rings of compacted Wyoming bentonite only, whereas the upper heater was surrounded by a composite barrier, with a sand shield between the heater and the bentonite. The test was dismantled and sampled during the winter of 2009/2010. This report presents the hydro-mechanical and chemical/mineralogical characterization program which was launched subsequent to the dismantling operation. The main goal has been to investigate if any significant differences could be observed between material from the field experiment and the reference material. The field samples were mainly taken from Ring 4 (located at the mid-section around the lower heater), in which the temperature in the innermost part reached 155 deg C. The following hydro-mechanical properties have been determined for the material (test technique within brackets): hydraulic conductivity (swelling pressure device), swelling pressure (swelling pressure device), unconfined compression strength (mechanical press), shear strength (triaxial cell) and retention properties (jar method). The following chemical/mineralogical properties (methods within brackets) were determined: anion analysis of water leachates (IC), chemical composition (ICP/AES+MS, EGA), cation exchange capacity (CEC, Cu-trien method) and exchangeable cations (exchange with NH4, ICPAES), mineralogical composition (XRD and FTIR), element distribution and microstructure (SEM and

Analytical methods of radwaste characterization

International Nuclear Information System (INIS)

Garcia, C.M.

1994-10-01

In view of the need to carry out more extensive studies on the design of newly proposed methods for the treatment of radioactive wastes collected at PNRI, this study is aimed to provide a guide in the characterization of wastes which is a preparatory step for a well-planned waste processing. (auth.). 8 refs

Biophysics of cancer progression and high-throughput mechanical characterization of biomaterials

Science.gov (United States)

Osborne, Lukas Dylan

Cancer metastasis involves a series of events known as the metastatic cascade. In this complex progression, cancer cells detach from the primary tumor, invade the surrounding stromal space, transmigrate the vascular system, and establish secondary tumors at distal sites. Specific mechanical phenotypes are likely adopted to enable cells to successfully navigate the mechanical environments encountered during metastasis. To examine the role of cell mechanics in cancer progression, I employed force-consistent biophysical and biochemical assays to characterize the mechanistic links between stiffness, stiffness response and cell invasion during the epithelial to mesenchymal transition (EMT). EMT is an essential physiological process, whose abnormal reactivation has been implicated in the detachment of cancer cells from epithelial tissue and their subsequent invasion into stromal tissue. I demonstrate that epithelial-state cells respond to force by evoking a stiffening response, and that after EMT, mesenchymal-state cells have reduced stiffness but also lose the ability to increase their stiffness in response to force. Using loss and gain of function studies, two proteins are established as functional connections between attenuated stiffness and stiffness response and the increased invasion capacity acquired after EMT. To enable larger scale assays to more fully explore the connection between biomechanics and cancer, I discuss the development of an automated array high throughput (AHT) microscope. The AHT system is shown to implement passive microbead rheology to accurately characterize the mechanical properties of biomaterials. Compared to manually performed mechanical characterizations, the AHT system executes experiments in two orders of magnitude less time. Finally, I use the AHT microscope to study the effect of gain of function oncogenic molecules on cell stiffness. I find evidence that our assay can identify alterations in cell stiffness due to constitutive

Characterization of Al–Al4C3 nanocomposites produced by mechanical milling

International Nuclear Information System (INIS)

Santos-Beltrán, A.; Goytia-Reyes, R.; Morales-Rodriguez, H.; Gallegos-Orozco, V.; Santos-Beltrán, M.; Baldenebro-Lopez, F.; Martínez-Sánchez, R.

2015-01-01

In this work, a mixture of Al–C–Al 4 C 3 nanopowder previously synthesized by mechanical milling and subsequent thermal treatment was used to reinforce the Al matrix. The nanocomposites were fabricated via high-energy ball milling and subsequent sintering process for different periods of time at 550 °C. Hardness and compression tests were performed to evaluate the mechanical properties of the nanocomposites in the as-milled and sintered conditions. According to the results the reinforcement located in the grain boundaries is responsible for the brittle behavior observed in the nanocomposites during the compression test. The combined effect of sintering and precipitation mechanisms produced an evident increase of the strength of the Al matrix at a relatively short sintering time. By using the Rietveld method the crystallite size and microstrain measurements were determined and correlated with the microhardness values. For the proper characterization of the nanoparticles present in the Al matrix, atomic force microscopy and high resolution electron microscopy were used. - Highlights: • Nanostructured Al 4 C 3 reinforcement was fabricated via mechanical milling and heat treatment. • We found a significant increase of the mechanical properties at short sintering times. • The formation of Al 4 C 3 with during sintering time restricted the excessive growth of the crystallite. • Al 4 C 3 located in the grain boundaries causes brittle fracture observed in compression tests. • There is a correlation between, crystallite size and microstrain values with microhardness

Mechanical Characterization and Corrosion Testing of X608 Al Alloy

Energy Technology Data Exchange (ETDEWEB)

Prabhakaran, Ramprashad; Choi, Jung-Pyung; Stephens, Elizabeth V.; Catalini, David; Lavender, Curt A.; Rohatgi, Aashish

2016-02-07

This paper describes the mechanical characterization and corrosion testing of X608 Al alloy that is being considered for A-pillar covers for heavy-duty truck applications. Recently, PNNL developed a thermo-mechanical process to stamp A-pillar covers at room temperature using this alloy, and the full-size prototype was successfully stamped by a tier-1 supplier. This study was conducted to obtain additional important information related to the newly developed forming process, and to further improve its mechanical properties. The solutionization temperature, pre-strain and paint-bake heat-treatment were found to influence the alloy’s fabricability and mechanical properties. Natural aging effect on the formability was investigated by limiting dome height (LDH) tests. Preliminary corrosion experiments showed that the employed thermo-mechanical treatments did not significantly affect the corrosion behavior of Al X608.

Characterization of porosity in support of mechanical property analysis

International Nuclear Information System (INIS)

Price, R.H.; Martin, R.J. III; Boyd, P.J.

1993-01-01

The general applicability of laboratory data for engineering purposes is a prime concern for the design and licensing of a potential repository of high level nuclear waste at Yucca Mountain. In order for the results of experiments to be applicable to the repository scale, the data must be scaled to in situ size and conditions. Previous laboratory investigations of tuff have shown that porosity has a dominant, general effect on mechanical properties. As a result, it is very important for the interpretation of mechanical property data that porosity is measured on each sampled test. Porosity alone, however, does not address all of the issues important to mechanical behavior. Variability in size and distribution of pore space produces significantly different mechanical properties. A nondestructive technique for characterizing the internal structure of the sample prior to testing is being developed and the results are being analyzed. The information obtained from this technique can help in both qualitative and quantitative interpretation of test results

Metrological evaluation of characterization methods applied to nuclear fuels

International Nuclear Information System (INIS)

Faeda, Kelly Cristina Martins; Lameiras, Fernando Soares; Camarano, Denise das Merces; Ferreira, Ricardo Alberto Neto; Migliorini, Fabricio Lima; Carneiro, Luciana Capanema Silva; Silva, Egonn Hendrigo Carvalho

2010-01-01

In manufacturing the nuclear fuel, characterizations are performed in order to assure the minimization of harmful effects. The uranium dioxide is the most used substance as nuclear reactor fuel because of many advantages, such as: high stability even when it is in contact with water at high temperatures, high fusion point, and high capacity to retain fission products. Several methods are used for characterization of nuclear fuels, such as thermogravimetric analysis for the ratio O / U, penetration-immersion method, helium pycnometer and mercury porosimetry for the density and porosity, BET method for the specific surface, chemical analyses for relevant impurities, and the laser flash method for thermophysical properties. Specific tools are needed to control the diameter and the sphericity of the microspheres and the properties of the coating layers (thickness, density, and degree of anisotropy). Other methods can also give information, such as scanning and transmission electron microscopy, X-ray diffraction, microanalysis, and mass spectroscopy of secondary ions for chemical analysis. The accuracy of measurement and level of uncertainty of the resulting data are important. This work describes a general metrological characterization of some techniques applied to the characterization of nuclear fuel. Sources of measurement uncertainty were analyzed. The purpose is to summarize selected properties of UO 2 that have been studied by CDTN in a program of fuel development for Pressurized Water Reactors (PWR). The selected properties are crucial for thermalhydraulic codes to study basic design accidents. The thermal characterization (thermal diffusivity and thermal conductivity) and the penetration immersion method (density and open porosity) of UO 2 samples were focused. The thermal characterization of UO 2 samples was determined by the laser flash method between room temperature and 448 K. The adaptive Monte Carlo Method was used to obtain the endpoints of the

Metrological evaluation of characterization methods applied to nuclear fuels

Energy Technology Data Exchange (ETDEWEB)

Faeda, Kelly Cristina Martins; Lameiras, Fernando Soares; Camarano, Denise das Merces; Ferreira, Ricardo Alberto Neto; Migliorini, Fabricio Lima; Carneiro, Luciana Capanema Silva; Silva, Egonn Hendrigo Carvalho, E-mail: kellyfisica@gmail.co, E-mail: fernando.lameiras@pq.cnpq.b, E-mail: dmc@cdtn.b, E-mail: ranf@cdtn.b, E-mail: flmigliorini@hotmail.co, E-mail: lucsc@hotmail.co, E-mail: egonn@ufmg.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2010-07-01

In manufacturing the nuclear fuel, characterizations are performed in order to assure the minimization of harmful effects. The uranium dioxide is the most used substance as nuclear reactor fuel because of many advantages, such as: high stability even when it is in contact with water at high temperatures, high fusion point, and high capacity to retain fission products. Several methods are used for characterization of nuclear fuels, such as thermogravimetric analysis for the ratio O / U, penetration-immersion method, helium pycnometer and mercury porosimetry for the density and porosity, BET method for the specific surface, chemical analyses for relevant impurities, and the laser flash method for thermophysical properties. Specific tools are needed to control the diameter and the sphericity of the microspheres and the properties of the coating layers (thickness, density, and degree of anisotropy). Other methods can also give information, such as scanning and transmission electron microscopy, X-ray diffraction, microanalysis, and mass spectroscopy of secondary ions for chemical analysis. The accuracy of measurement and level of uncertainty of the resulting data are important. This work describes a general metrological characterization of some techniques applied to the characterization of nuclear fuel. Sources of measurement uncertainty were analyzed. The purpose is to summarize selected properties of UO{sub 2} that have been studied by CDTN in a program of fuel development for Pressurized Water Reactors (PWR). The selected properties are crucial for thermalhydraulic codes to study basic design accidents. The thermal characterization (thermal diffusivity and thermal conductivity) and the penetration immersion method (density and open porosity) of UO{sub 2} samples were focused. The thermal characterization of UO{sub 2} samples was determined by the laser flash method between room temperature and 448 K. The adaptive Monte Carlo Method was used to obtain the endpoints of

Transuranic waste characterization sampling and analysis methods manual. Revision 1

International Nuclear Information System (INIS)

Suermann, J.F.

1996-04-01

This Methods Manual provides a unified source of information on the sampling and analytical techniques that enable Department of Energy (DOE) facilities to comply with the requirements established in the current revision of the Transuranic Waste Characterization Quality Assurance Program Plan (QAPP) for the Waste Isolation Pilot Plant (WIPP) Transuranic (TRU) Waste Characterization Program (the Program) and the WIPP Waste Analysis Plan. This Methods Manual includes all of the testing, sampling, and analytical methodologies accepted by DOE for use in implementing the Program requirements specified in the QAPP and the WIPP Waste Analysis Plan. The procedures in this Methods Manual are comprehensive and detailed and are designed to provide the necessary guidance for the preparation of site-specific procedures. With some analytical methods, such as Gas Chromatography/Mass Spectrometry, the Methods Manual procedures may be used directly. With other methods, such as nondestructive characterization, the Methods Manual provides guidance rather than a step-by-step procedure. Sites must meet all of the specified quality control requirements of the applicable procedure. Each DOE site must document the details of the procedures it will use and demonstrate the efficacy of such procedures to the Manager, National TRU Program Waste Characterization, during Waste Characterization and Certification audits

A constitutive model for the mechanical characterization of the plantar fascia.

Science.gov (United States)

Natali, Arturo N; Pavan, Piero G; Stecco, Carla

2010-10-01

A constitutive model is proposed to describe the mechanical behavior of the plantar fascia. The mechanical characterization of the plantar fascia regards the role in the foot biomechanics and it is involved in many alterations of its functional behavior, both of mechanical and nonmechanical origin. The structural conformation of the plantar fascia in its middle part is characterized by the presence of collagen fibers reinforcing the tissue along a preferential orientation, which is that supporting the major loading. According to this anatomical evidence, the tissue is described by developing an isotropic fiber-reinforced constitutive model and since the elastic response of the fascia is here considered, the constitutive model is based on the theory of hyperelasticity. The model is consistent with a kinematical description of large strains mechanical behavior, which is typical of soft tissues. A fitting procedure of the constitutive model is implemented making use of experimental curves taken from the literature and referring to specimens of human plantar fascia. A satisfactory fitting of the tensile behavior of the plantar fascia has been performed, showing that the model correctly interprets the mechanical behavior of the tissue in the light of comparison to experimental data at disposal. A critical analysis of the model with respect to the problem of the identification of the constitutive parameters is proposed as the basis for planning a future experimental investigation of mechanical behavior of the plantar fascia.

Linear-scaling quantum mechanical methods for excited states.

Science.gov (United States)

Yam, ChiYung; Zhang, Qing; Wang, Fan; Chen, GuanHua

2012-05-21

The poor scaling of many existing quantum mechanical methods with respect to the system size hinders their applications to large systems. In this tutorial review, we focus on latest research on linear-scaling or O(N) quantum mechanical methods for excited states. Based on the locality of quantum mechanical systems, O(N) quantum mechanical methods for excited states are comprised of two categories, the time-domain and frequency-domain methods. The former solves the dynamics of the electronic systems in real time while the latter involves direct evaluation of electronic response in the frequency-domain. The localized density matrix (LDM) method is the first and most mature linear-scaling quantum mechanical method for excited states. It has been implemented in time- and frequency-domains. The O(N) time-domain methods also include the approach that solves the time-dependent Kohn-Sham (TDKS) equation using the non-orthogonal localized molecular orbitals (NOLMOs). Besides the frequency-domain LDM method, other O(N) frequency-domain methods have been proposed and implemented at the first-principles level. Except one-dimensional or quasi-one-dimensional systems, the O(N) frequency-domain methods are often not applicable to resonant responses because of the convergence problem. For linear response, the most efficient O(N) first-principles method is found to be the LDM method with Chebyshev expansion for time integration. For off-resonant response (including nonlinear properties) at a specific frequency, the frequency-domain methods with iterative solvers are quite efficient and thus practical. For nonlinear response, both on-resonance and off-resonance, the time-domain methods can be used, however, as the time-domain first-principles methods are quite expensive, time-domain O(N) semi-empirical methods are often the practical choice. Compared to the O(N) frequency-domain methods, the O(N) time-domain methods for excited states are much more mature and numerically stable, and

MECHANISM OF BORAX CRYSTALLIZATION USING CONDUCTIVITY METHOD

OpenAIRE

Suharso, Suharso

2010-01-01

The kinetics of crystal growth of borax has been studied by using conductivity method at temperature of 25 °C and at various relative supersaturations. It was found that the growth rate increases with increasing supersaturation. At low concentration, growth occurs via a spiral growth mechanism and at high concentration birth and spread is the principal mechanism operating.     Keywords: borax; growth rate; crystallization; conductivity method

The ISRM suggested methods for rock characterization, testing and monitoring 2007-2014

CERN Document Server

2015-01-01

This book is a collection of ISRM suggested methods for testing or measuring properties of rocks and rock masses both in the laboratory and in situ, as well as for monitoring the performance of rock engineering structures. The first collection (Yellow Book) has been published in 1981. In order to provide access to all the Suggested Methods in one volume, the ISRM Blue Book was published in 2007 (by the ISRM via the Turkish National Group) and contains the complete set of Suggested Methods from 1974 to 2006 inclusive. The papers in this most recent volume have been published during the last seven years in international journals, mainly in Rock Mechanics and Rock Engineering. They offer guidance for rock characterization procedures and laboratory and field testing and monitoring in rock engineering. These methods provide a definitive procedure for the identification, measurement and evaluation of one or more qualities, characteristics, or properties of rocks or rock systems that produces a test result.

Waste Characterization Methods

Energy Technology Data Exchange (ETDEWEB)

Vigil-Holterman, Luciana R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Naranjo, Felicia Danielle [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2016-02-02

This report discusses ways to classify waste as outlined by LANL. Waste Generators must make a waste determination and characterize regulated waste by appropriate analytical testing or use of acceptable knowledge (AK). Use of AK for characterization requires several source documents. Waste characterization documentation must be accurate, sufficient, and current (i.e., updated); relevant and traceable to the waste stream’s generation, characterization, and management; and not merely a list of information sources.

Waste Characterization Methods

International Nuclear Information System (INIS)

Vigil-Holterman, Luciana R.; Naranjo, Felicia Danielle

2016-01-01

This report discusses ways to classify waste as outlined by LANL. Waste Generators must make a waste determination and characterize regulated waste by appropriate analytical testing or use of acceptable knowledge (AK). Use of AK for characterization requires several source documents. Waste characterization documentation must be accurate, sufficient, and current (i.e., updated); relevant and traceable to the waste stream's generation, characterization, and management; and not merely a list of information sources.

Mechanical, chemical and radiological characterization of the graphite of the UNGG reactors type

International Nuclear Information System (INIS)

Bresard, I.; Bonal, J.P.

2000-01-01

In the framework of UNGG reactors type dismantling procedures, the characterization of the graphite, used as moderator, has to be realized. This paper presents the mechanical, chemical and radiological characterizations, the properties measured and gives some results in the case of the Bugey 1 reactor. (A.L.B.)

MECHANISM OF BORAX CRYSTALLIZATION USING CONDUCTIVITY METHOD

Directory of Open Access Journals (Sweden)

Suharso Suharso

2010-06-01

Full Text Available The kinetics of crystal growth of borax has been studied by using conductivity method at temperature of 25 °C and at various relative supersaturations. It was found that the growth rate increases with increasing supersaturation. At low concentration, growth occurs via a spiral growth mechanism and at high concentration birth and spread is the principal mechanism operating.     Keywords: borax; growth rate; crystallization; conductivity method

Numerical methods for characterization of synchrotron radiation based on the Wigner function method

Directory of Open Access Journals (Sweden)

Takashi Tanaka

2014-06-01

Full Text Available Numerical characterization of synchrotron radiation based on the Wigner function method is explored in order to accurately evaluate the light source performance. A number of numerical methods to compute the Wigner functions for typical synchrotron radiation sources such as bending magnets, undulators and wigglers, are presented, which significantly improve the computation efficiency and reduce the total computation time. As a practical example of the numerical characterization, optimization of betatron functions to maximize the brilliance of undulator radiation is discussed.

Development of subsurface characterization method for decommissioning site remediation

Energy Technology Data Exchange (ETDEWEB)

Hong, Sang Bum; Nam, Jong Soo; Choi, Yong Suk; Seo, Bum Kyoung; Moon, Jei Kwon; Choi, Jong Won [KAERI, Daejeon (Korea, Republic of)

2016-05-15

In situ measurement of peak to valley method based on the ratio of counting rate between the full energy peak and Compton region was applied to identify the depth distribution of 137Cs. The In situ measurement and sampling results were applied to evaluate a residual radioactivity before and after remediation in decommissioning KRR site. Spatial analysis based on the Geostatistics method provides a reliable estimating the volume of contaminated soil with a graphical analysis, which was applied to the site characterization in the decommissioning KRR site. The in situ measurement and spatial analysis results for characterization of subsurface contamination are presented. The objective of a remedial action is to reduce risks to human health to acceptable levels by removing the source of contamination. Site characterization of the subsurface contamination is an important factor for planning and implementation of site remediation. Radiological survey and evaluation technology are required to ensure the reliability of the results, and the process must be easily applied during field measurements. In situ gamma-ray spectrometry is a powerful method for site characterization that can be used to identify the depth distribution and quantify radionuclides directly at the measurement site. The in situ measurement and Geostatistics method was applied to the site characterization for remediation and final status survey in decommissioning KRR site.

Soil characterization methods for unsaturated low-level waste sites

International Nuclear Information System (INIS)

Wierenga, P.J.; Young, M.H.; Hills, R.G.

1993-01-01

To support a license application for the disposal of low-level radioactive waste (LLW), applicants must characterize the unsaturated zone and demonstrate that waste will not migrate from the facility boundary. This document provides a strategy for developing this characterization plan. It describes principles of contaminant flow and transport, site characterization and monitoring strategies, and data management. It also discusses methods and practices that are currently used to monitor properties and conditions in the soil profile, how these properties influence water and waste migration, and why they are important to the license application. The methods part of the document is divided into sections on laboratory and field-based properties, then further subdivided into the description of methods for determining 18 physical, flow, and transport properties. Because of the availability of detailed procedures in many texts and journal articles, the reader is often directed for details to the available literature. References are made to experiments performed at the Las Cruces Trench site, New Mexico, that support LLW site characterization activities. A major contribution from the Las Cruces study is the experience gained in handling data sets for site characterization and the subsequent use of these data sets in modeling studies

Modeling Mechanical Properties of Aluminum Composite Produced Using Stir Casting Method

Directory of Open Access Journals (Sweden)

Muhammad Hayat Jokhio

2011-01-01

Full Text Available ANN (Artificial Neural Networks modeling methodology was adopted for predicting mechanical properties of aluminum cast composite materials. For this purpose aluminum alloy were developed using conventional foundry method. The composite materials have complex nature which posses the nonlinear relationship among heat treatment, processing parameters, and composition and affects their mechanical properties. These nonlinear relation ships with properties can more efficiently be modeled by ANNs. Neural networks modeling needs sufficient data base consisting of mechanical properties, chemical composition and processing parameters. Such data base is not available for modeling. Therefore, a large range of experimental work was carried out for the development of aluminum composite materials. Alloys containing Cu, Mg and Zn as matrix were reinforced with 1- 15% Al2O3 particles using stir casting method. Alloys composites were cast in a metal mold. More than eighty standard samples were prepared for tensile tests. Sixty samples were given solution treatments at 580oC for half an hour and tempered at 120oC for 24 hours. The samples were characterized to investigate mechanical properties using Scanning Electron Microscope, X-Ray Spectrometer, Optical Metallurgical Microscope, Vickers Hardness, Universal Testing Machine and Abrasive Wear Testing Machine. A MLP (Multilayer Perceptron feedforward was developed and used for modeling purpose. Training, testing and validation of the model were carried out using back propagation learning algorithm. The modeling results show that an architecture of 14 inputs with 9 hidden neurons and 4 outputs which includes the tensile strength, elongation, hardness and abrasive wear resistance gives reasonably accurate results with an error within the range of 2-7 % in training, testing and validation.

Modeling mechanical properties of aluminum composite produced using stir casting method

International Nuclear Information System (INIS)

Jokhio, M.H.; Panhwar, M.I.; Unar, M.A.

2011-01-01

ANN (Artificial Neural Networks) modeling methodology was adopted for predicting mechanical properties of aluminum cast composite materials. For this purpose aluminum alloy were developed using conventional foundry method. The composite materials have complex nature which posses the nonlinear relationship among heat treatment, processing parameters, and composition and affects their mechanical properties. These nonlinear relation ships with properties can more efficiently be modeled by ANNs. Neural networks modeling needs sufficient data base consisting of mechanical properties, chemical composition and processing parameters. Such data base is not available for modeling. Therefore, a large range of experimental work was carried out for the development of aluminum composite materials. Alloys containing Cu, Mg and Zn as matrix were reinforced with 1- 15% AI/sub 2/O/sub 3/ particles using stir casting method. Alloys composites were cast in a metal mold. More than eighty standard samples were prepared for tensile tests. Sixty samples were given solution treatments at 580 deg. C for half an hour and tempered at 120 deg. C for 24 hours. The samples were characterized to investigate mechanical properties using Scanning Electron Microscope, X-Ray Spectrometer, Optical Metallurgical Microscope, Vickers Hardness, Universal Testing Machine and Abrasive Wear Testing Machine. A MLP (Multilayer Perceptron) feed forward was developed and used for modeling purpose. Training, testing and validation of the model were carried out using back propagation learning algorithm. The modeling results show that an architecture of 14 inputs with 9 hidden neurons and 4 outputs which includes the tensile strength, elongation, hardness and abrasive wear resistance gives reasonably accurate results with an error within the range of 2-7 % in training, testing and validation. (author)

Quantum mechanical approaches to in silico enzyme characterization and drug design

Energy Technology Data Exchange (ETDEWEB)

Nilmeier, J P; Fattebert, J L; Jacobson, M P; Kalyanaraman, C

2012-01-17

The astonishing, exponentially increasing rates of genome sequencing has led to one of the most significant challenges for the biological and computational sciences in the 21st century: assigning the likely functions of the encoded proteins. Enzymes represent a particular challenge, and a critical one, because the universe of enzymes is likely to contain many novel functions that may be useful for synthetic biology, or as drug targets. Current approaches to protein annotation are largely based on bioinformatics. At the simplest level, this annotation involves transferring the annotations of characterized enzymes to related sequences. In practice, however, there is no simple, sequence based criterion for transferring annotations, and bioinformatics alone cannot propose new enzymatic functions. Structure-based computational methods have the potential to address these limitations, by identifying potential substrates of enzymes, as we and others have shown. One successful approach has used in silico 'docking' methods, more commonly applied in structure-based drug design, to identify possible metabolite substrates. A major limitation of this approach is that it only considers substrate binding, and does not directly assess the potential of the enzyme to catalyze a particular reaction using a particular substrate. That is, substrate binding affinity is necessary but not sufficient to assign function. A reaction profile is ultimately what is needed for a more complete quantitative description of function. To address this rather fundamental limitation, they propose to use quantum mechanical methods to explicitly compute transition state barriers that govern the rates of catalysis. Although quantum mechanical, and mixed quantum/classical (QM/MM), methods have been used extensively to investigate enzymatic reactions, the focus has been primarily on elucidating complex reaction mechanisms. Here, the key catalytic steps are known, and they use these methods quantify

Mechanical Characterization of Nanoporous Thin Films by Nanoindentation and Laser-induced Surface Acoustic Waves

Science.gov (United States)

Chow, Gabriel

wavelengths are micrometers in scale whereas indentation depths are usually confined to the nanometer scale. This dissertation demonstrates the effectiveness of LiSAW on both thin porous layers and rough surfaces and shows the challenges faced by nanoindentation on the same films. Zeolite thin films are studied extensively in this work as a model system because of their porous crystalline framework and enormous economic market. Many types of zeolite exist and their widely varying structures and levels of porosity present a unique opportunity for mechanical characterization. For a fully dense ZSM-5 type zeolite with wear and corrosion resistance properties, nanoindentation was used to compare its mechanical properties to industrial chromium and cadmium films. Through tribological and indentation tests, it was shown that the zeolite film possesses exceptional resilience and hardness therefore demonstrating superior wear resistance to chromium and cadmium. This also highlighted the quality of nanoindentation measurements on thick dense layers where traditional nanoindentation excels. Nanoindentation was then performed on porous and non-porous MFI zeolite films with low-k (low dielectric constant) properties. These films were softer and much thinner than the ZSM-5 coatings resulting in significant substrate effects, evidenced by inflation of the measurements from the hard silicon substrate, during indentation. Such effects were avoided with the LiSAW technique on the same films where properties were readily extracted without complications. An alternative indentation analysis method was demonstrated to produce accurate mechanical measurements in line with the LiSAW results, but the non-traditional technique requires substantial computational intensity. Thus LiSAW was proven to be an accurate and efficient means of mechanical characterization for thin porous layers. The case for LiSAW was further supported by utilizing the technique on a porous nanostructured V2O5 electrode film

APPLICATIONS OF BOREHOLE-ACOUSTIC METHODS IN ROCK MECHANICS.

Science.gov (United States)

Paillet, Frederick L.

1985-01-01

Acoustic-logging methods using a considerable range of wavelengths and frequencies have proven very useful in the in situ characterization of deeply buried crystalline rocks. Seismic velocities are useful in investigating the moduli of unfractured rock, and in producing a continuous record of rock quality for comparison with discontinuous intervals of core. The considerable range of frequencies makes the investigation of scale effects possible in both fractured and unfractured rock. Several specific methods for the characterization of in situ permeability have been developed and verified in the field.

Multi-scale mechanical characterization of scaffolds for heart valve tissue engineering

NARCIS (Netherlands)

Argento, G.; Simonet, M.; Oomens, C.W.J.; Baaijens, F.P.T.

2012-01-01

Electrospinning is a promising technology to produce scaffolds for cardiovascular tissue engineering. Each electrospun scaffold is characterized by a complex micro-scale structure that is responsible for its macroscopic mechanical behavior. In this study, we focus on the development and the

comparison of elastic-plastic FE method and engineering method for RPV fracture mechanics analysis

International Nuclear Information System (INIS)

Sun Yingxue; Zheng Bin; Zhang Fenggang

2009-01-01

This paper described the FE analysis of elastic-plastic fracture mechanics for a crack in RPV belt line using ABAQUS code. It calculated and evaluated the stress intensity factor and J integral of crack under PTS transients. The result is also compared with that by engineering analysis method. It shows that the results using engineering analysis method is a little larger than the results using FE analysis of 3D elastic-plastic fracture mechanics, thus the engineering analysis method is conservative than the elastic-plastic fracture mechanics method. (authors)

Preparation, characterization and mechanical properties of k ...

Indian Academy of Sciences (India)

2017-06-09

Jun 9, 2017 ... Nanocomposite; k-Carrageenan; SiO2 nanoparticles; mechanical strength; antimicrobial activity. 1. Introduction ... Silicon dioxide (SiO2)-filled polymer matrix com- posites have ... by using the agar disk diffusion method. 2.

Characterization techniques to predict mechanical behaviour of green ceramic bodies fabricated by ceramic microstereolithography

Science.gov (United States)

Adake, Chandrashekhar V.; Bhargava, Parag; Gandhi, Prasanna

2018-02-01

Ceramic microstereolithography (CMSL) has emerged as solid free form (SFF) fabrication technology in which complex ceramic parts are fabricated from ceramic suspensions which are formulated by dispersing ceramic particles in UV curable resins. Ceramic parts are fabricated by exposing ceramic suspension to computer controlled UV light which polymerizes resin to polymer and this polymer forms rigid network around ceramic particles. A 3-dimensional part is created by piling cured layers one over the other. These ceramic parts are used to build microelectromechanical (MEMS) devices after thermal treatment. In many cases green ceramic parts can be directly utilized to build MEMS devices. Hence characterization of these parts is essential in terms of their mechanical behaviour prior to their use in MEMS devices. Mechanical behaviour of these green ceramic parts depends on cross link density which in turn depends on chemical structure of monomer, concentrations of photoinitiator and UV energy dose. Mechanical behaviour can be determined with the aid of nanoindentation. And extent of crosslinking can be verified with the aid of DSC. FTIR characterization is used to analyse (-C=C-) double bond conversion. This paper explains characterization tools to predict the mechanical behaviour of green ceramic bodies fabricated in CMSL

Methods for evaluation of mechanical stress condition of materials

Directory of Open Access Journals (Sweden)

Mirchev Yordan

2018-01-01

Full Text Available Primary attention is given to the following methods: method by drilling cylindrical holes (drill method and integrated ultrasonic method using volume (longitudinal and transverse, surface, and sub-surface waves. Drill method allows determination of residual mechanical stress in small depth of material surfaces, assessing type, size, and orientation of principal stresses. For the first time, parallel studies are carried out of mechanical stress in materials using the electroacoustic effect of volume, surface and sub-surface waves on the one hand, and effective mechanical stresses on the other. The experimental results present electroacoustic coefficients for different types of waves in the material of gas pipeline tube of 243 mm diameter and 14 mm thickness. These are used to evaluate mechanical stresses in pipelines, according to active GOST standards.

Towards the mechanical characterization of abdominal wall by inverse analysis.

Science.gov (United States)

Simón-Allué, R; Calvo, B; Oberai, A A; Barbone, P E

2017-02-01

The aim of this study is to characterize the passive mechanical behaviour of abdominal wall in vivo in an animal model using only external cameras and numerical analysis. The main objective lies in defining a methodology that provides in vivo information of a specific patient without altering mechanical properties. It is demonstrated in the mechanical study of abdomen for hernia purposes. Mechanical tests consisted on pneumoperitoneum tests performed on New Zealand rabbits, where inner pressure was varied from 0mmHg to 12mmHg. Changes in the external abdominal surface were recorded and several points were tracked. Based on their coordinates we reconstructed a 3D finite element model of the abdominal wall, considering an incompressible hyperelastic material model defined by two parameters. The spatial distributions of these parameters (shear modulus and non linear parameter) were calculated by inverse analysis, using two different types of regularization: Total Variation Diminishing (TVD) and Tikhonov (H 1 ). After solving the inverse problem, the distribution of the material parameters were obtained along the abdominal surface. Accuracy of the results was evaluated for the last level of pressure. Results revealed a higher value of the shear modulus in a wide stripe along the craneo-caudal direction, associated with the presence of linea alba in conjunction with fascias and rectus abdominis. Non linear parameter distribution was smoother and the location of higher values varied with the regularization type. Both regularizations proved to yield in an accurate predicted displacement field, but H 1 obtained a smoother material parameter distribution while TVD included some discontinuities. The methodology here presented was able to characterize in vivo the passive non linear mechanical response of the abdominal wall. Copyright © 2016 Elsevier Ltd. All rights reserved.

Monte Carlo method to characterize radioactive waste drums

International Nuclear Information System (INIS)

Lima, Josenilson B.; Dellamano, Jose C.; Potiens Junior, Ademar J.

2013-01-01

Non-destructive methods for radioactive waste drums characterization have being developed in the Waste Management Department (GRR) at Nuclear and Energy Research Institute IPEN. This study was conducted as part of the radioactive wastes characterization program in order to meet specifications and acceptance criteria for final disposal imposed by regulatory control by gamma spectrometry. One of the main difficulties in the detectors calibration process is to obtain the counting efficiencies that can be solved by the use of mathematical techniques. The aim of this work was to develop a methodology to characterize drums using gamma spectrometry and Monte Carlo method. Monte Carlo is a widely used mathematical technique, which simulates the radiation transport in the medium, thus obtaining the efficiencies calibration of the detector. The equipment used in this work is a heavily shielded Hyperpure Germanium (HPGe) detector coupled with an electronic setup composed of high voltage source, amplifier and multiport multichannel analyzer and MCNP software for Monte Carlo simulation. The developing of this methodology will allow the characterization of solid radioactive wastes packed in drums and stored at GRR. (author)

Drive mechanism nuclear reactor control rod

International Nuclear Information System (INIS)

Brooks, J.G. Jr.; Maure, D.R.; Meijer, C.H.

1978-01-01

An improved method and apparatus for operating magnetic stepping-type mechanisms. The current flowing in the coils of magnetic stepping-type mechanisms of the kind, for instance, that are used in control-element drive mechanisms is sensed and used to monitor operation of the mechanism. Current waveforms that characterize the motion of the mechanism are used to trigger changes in drive voltage and to verify that the drive mechanism is operating properly. In addition, incipient failures are detected through the observation of differences between the observed waveform and waveforms that characterize proper operation

Nanomechanical Pyrolytic Carbon Resonators: Novel Fabrication Method and Characterization of Mechanical Properties

Directory of Open Access Journals (Sweden)

Maksymilian Kurek

2016-07-01

Full Text Available Micro- and nanomechanical string resonators, which essentially are highly stressed bridges, are of particular interest for micro- and nanomechanical sensing because they exhibit resonant behavior with exceptionally high quality factors. Here, we fabricated and characterized nanomechanical pyrolytic carbon resonators (strings and cantilevers obtained through pyrolysis of photoresist precursors. The developed fabrication process consists of only three processing steps: photolithography, dry etching and pyrolysis. Two different fabrication strategies with two different photoresists, namely SU-8 2005 (negative and AZ 5214e (positive, were compared. The resonant behavior of the pyrolytic resonators was characterized at room temperature and in high vacuum using a laser Doppler vibrometer. The experimental data was used to estimate the Young’s modulus of pyrolytic carbon and the tensile stress in the string resonators. The Young’s moduli were calculated to be 74 ± 8 GPa with SU-8 and 115 ± 8 GPa with AZ 5214e as the precursor. The tensile stress in the string resonators was 33 ± 7 MPa with AZ 5214e as the precursor. The string resonators displayed maximal quality factor values of up to 3000 for 525-µm-long structures.

Scanning probe microscopy techniques for mechanical characterization at nanoscale

International Nuclear Information System (INIS)

Passeri, D.; Anastasiadis, P.; Tamburri, E.; Gugkielmotti, V.; Rossi, M.

2013-01-01

Three atomic force microscopy (AFM)-based techniques are reviewed that allow one to conduct accurate measurements of mechanical properties of either stiff or compliant materials at a nanometer scale. Atomic force acoustic microscopy, AFM-based depth sensing indentation, and torsional harmonic AFM are briefly described. Examples and results of quantitative characterization of stiff (an ultrathin SeSn film), soft polymeric (polyaniline fibers doped with detonation nanodiamond) and biological (collagen fibers) materials are reported.

Characterization and modeling of mechanical behavior of quenching and partitioning steels

International Nuclear Information System (INIS)

Arlazarov, A.; Bouaziz, O.; Masse, J.P.; Kegel, F.

2015-01-01

Q and P annealing was applied to cold rolled carbon–manganese steel with Si. Q and P cycles with different partitioning temperature and time were simulated and the evolution of microstructure and mechanical properties was investigated. All the microstructures were composed of three constituents: partitioned martensite, laths of retained austenite and MA islands. Fine microstructure characterization confirmed that C diffusion plays an important role for the stabilization of retained austenite at room temperature and further TRIP effect during mechanical loading. Good compromise between yield strength (∼1200 MPa) and uniform elongation (∼11%) was found in the case of 400 °C partitioning for 300 s due to the enhanced mechanical stability of retained austenite. Evolution of microstructure and mechanical properties was discussed and some mechanisms were proposed to explain the observations. Mechanical model for the prediction of stress–strain curves of Q and P steels was proposed, based on the obtained experimental data. Accurate prediction of stress–strain curves using model was achieved

Characterization and modeling of mechanical behavior of quenching and partitioning steels

Energy Technology Data Exchange (ETDEWEB)

Arlazarov, A., E-mail: artem.arlazarov@arcelormittal.com [ArcelorMittal Global Research and Development, Voie Romaine-BP30320, 57283 Maizières-lès-Metz Cedex (France); Laboratoire d’Etude des Microstructures et de Mécanique des Matériaux (LEM3), CNRS UMR 7239, Université de Lorraine, 57012 Metz Cedex (France); Bouaziz, O. [ArcelorMittal Global Research and Development, Voie Romaine-BP30320, 57283 Maizières-lès-Metz Cedex (France); Laboratoire d’Etude des Microstructures et de Mécanique des Matériaux (LEM3), CNRS UMR 7239, Université de Lorraine, 57012 Metz Cedex (France); Masse, J.P.; Kegel, F. [ArcelorMittal Global Research and Development, Voie Romaine-BP30320, 57283 Maizières-lès-Metz Cedex (France)

2015-01-03

Q and P annealing was applied to cold rolled carbon–manganese steel with Si. Q and P cycles with different partitioning temperature and time were simulated and the evolution of microstructure and mechanical properties was investigated. All the microstructures were composed of three constituents: partitioned martensite, laths of retained austenite and MA islands. Fine microstructure characterization confirmed that C diffusion plays an important role for the stabilization of retained austenite at room temperature and further TRIP effect during mechanical loading. Good compromise between yield strength (∼1200 MPa) and uniform elongation (∼11%) was found in the case of 400 °C partitioning for 300 s due to the enhanced mechanical stability of retained austenite. Evolution of microstructure and mechanical properties was discussed and some mechanisms were proposed to explain the observations. Mechanical model for the prediction of stress–strain curves of Q and P steels was proposed, based on the obtained experimental data. Accurate prediction of stress–strain curves using model was achieved.

Mechanical Characterization of Polydopamine-Assisted Silver Deposition on Polymer Substrates

Science.gov (United States)

Cordes, Amanda Laurence

Inspired by the adhesive proteins in marine mussels, polydopamine has become a popular adhesive ad-layer for surface functionalization of a variety of substrates. Based on the chemistry of the dopamine monomer, amine and thiol functional groups are hypothesized to increase adhesion between polymer substrates and polydopamine thin films. This hypothesis was the central motivation for development of a tailorable thiol-ene system in order to study the effects of substrate chemistry on polydopamine adhesion. While polydopamine-adhered silver has been studied on a variety of substrates, no in depth mechanical characterization has been performed and to date, no research has been published on thiol-enes coated in polydopamine-adhered silver. The purpose of this study was to characterize the mechanical durability and adhesion properties of a polydopamine-adhered silver film on commercial substrates and a tailorable thiol-ene system. Polydopamine and silver coatings were deposited on a variety of polymer substrates through a simple dip-coat process. The polydopamine forms a thin uniform adhesive layer and the silver deposits in a discontinuous manner with a nanoparticle sized base layer covering the full surface and micron-sized clusters adhered sporadically on top. Mechanical tensile testing was performed to characterize the durability of the silver coating on commercial polymers. Coated nylon and HDPE showed no signs of degradation or delamination of the polydopamine-adhered silver coating up to 30% strain although both substrates showed large plastic deformation. Peel tests were performed on both commercial polymers as well as a tailorable thiol-ene system. Results support the hypothesis that polydopamine adhesion is increased with the presence of functional groups. Parts of the HDPE sample were cleanly peeled, but silver patches were left sporadically across the surface pointing to weaker adhesion between polyethylene and polydopamine. A high adhesive strength tape was

Characterization methods for ultrasonic test systems

International Nuclear Information System (INIS)

Busse, L.J.; Becker, F.L.; Bowey, R.E.; Doctor, S.R.; Gribble, R.P.; Posakony, G.J.

1982-07-01

Methods for the characterization of ultrasonic transducers (search units) and instruments are presented. The instrument system is considered as three separate components consisting of a transducer, a receiver-display, and a pulser. The operation of each component is assessed independently. The methods presented were chosen because they provide the greatest amount of information about component operation and were not chosen based upon such conditions as cost, ease of operation, field implementation, etc. The results of evaluating a number of commercially available ultrasonic test instruments are presented

Preparation and Characterization of Nano-structured Ceramic Powders Synthesized by Emulsion Combustion Method

International Nuclear Information System (INIS)

Takatori, Kazumasa; Tani, Takao; Watanabe, Naoyoshi; Kamiya, Nobuo

1999-01-01

The emulsion combustion method (ECM), a novel powder production process, was originally developed to synthesize nano-structured metal-oxide powders. Metal ions in the aqueous droplets were rapidly oxidized by the combustion of the surrounding flammable liquid. The ECM achieved a small reaction field and a short reaction period to fabricate the submicron-sized hollow ceramic particles with extremely thin wall and chemically homogeneous ceramic powder. Alumina, zirconia, zirconia-ceria solid solutions and barium titanate were synthesized by the ECM process. Alumina and zirconia powders were characterized to be metastable in crystalline phase and hollow structure. The wall thickness of alumina was about 10 nm. The zirconia-ceria powders were found to be single-phase solid solutions for a wide composition range. These powders were characterized as equiaxed-shape, submicron-sized chemically homogeneous materials. The powder formation mechanism was investigated through the synthesis of barium titanate powder with different metal sources

Mechanical characterization of atherosclerotic arteries using finite-element modeling: feasibility study on mock arteries.

Science.gov (United States)

Pazos, Valérie; Mongrain, Rosaire; Tardif, Jean-Claude

2010-06-01

Clinical studies on lipid-lowering therapy have shown that changing the composition of lipid pools reduced significantly the risk of cardiac events associated with plaque rupture. It has been shown also that changing the composition of the lipid pool affects its mechanical properties. However, knowledge about the mechanical properties of human atherosclerotic lesions remains limited due to the difficulty of the experiments. This paper aims to assess the feasibility of characterizing a lipid pool embedded in the wall of a pressurized vessel using finite-element simulations and an optimization algorithm. Finite-element simulations of inflation experiments were used together with nonlinear least squares algorithm to estimate the material model parameters of the wall and of the inclusion. An optimal fit of the simulated experiment and the real experiment was sought with the parameter estimation algorithm. The method was first tested on a single-layer polyvinyl alcohol (PVA) cryogel stenotic vessel, and then, applied on a double-layered PVA cryogel stenotic vessel with a lipid inclusion.

A Method for Identifying the Mechanical Parameters in Resistance Spot Welding Machines

DEFF Research Database (Denmark)

Wu, Pei; Zhang, Wenqi; Bay, Niels

2003-01-01

Mechanical dynamic responses of resistance welding machine have a significant influence on weld quality and electrode service life, it must be considered when the real welding production is carried out or the welding process is stimulated. The mathematical models for characterizing the mechanical...

Stochastic methods in quantum mechanics

CERN Document Server

Gudder, Stanley P

2005-01-01

Practical developments in such fields as optical coherence, communication engineering, and laser technology have developed from the applications of stochastic methods. This introductory survey offers a broad view of some of the most useful stochastic methods and techniques in quantum physics, functional analysis, probability theory, communications, and electrical engineering. Starting with a history of quantum mechanics, it examines both the quantum logic approach and the operational approach, with explorations of random fields and quantum field theory.The text assumes a basic knowledge of fun

Rock mass mechanical property estimations for the Yucca Mountain Site Characterization Project

International Nuclear Information System (INIS)

Lin, M.; Hardy, M.P.; Bauer, S.J.

1993-06-01

Rock mass mechanical properties are important in the design of drifts and ramps. These properties are used in evaluations of the impacts of thermomechanical loading of potential host rock within the Yucca Mountain Site Characterization Project. Representative intact rock and joint mechanical properties were selected for welded and nonwelded tuffs from the currently available data sources. Rock mass qualities were then estimated using both the Norwegian Geotechnical Institute (Q) and Geomechanics Rating (RMR) systems. Rock mass mechanical properties were developed based on estimates of rock mass quality, the current knowledge of intact properties, and fracture/joint characteristics. Empirical relationships developed to correlate the rock mass quality indices and the rock mass mechanical properties were then used to estimate the range of rock mass mechanical properties

Mechanical and microstructural characterization of powder metallurgy CoCrNi medium entropy alloy

Czech Academy of Sciences Publication Activity Database

Moravčík, I.; Čížek, Jan; Kováčová, Z.; Nejezchlebová, J.; Kitzmantel, M.; Neubauer, E.; Kuběna, Ivo; Horník, Vít; Dlouhý, I.

2017-01-01

Roč. 701, July (2017), s. 370-380 ISSN 0921-5093 Institutional support: RVO:61389021 ; RVO:68081723 Keywords : tensile test * mechanical alloying * plastic ity * mechanical characterization * powder metallurgy Subject RIV: JG - Metallurgy; JG - Metallurgy (UFM-A) OBOR OECD: Materials engineering; Materials engineering (UFM-A) Impact factor: 3.094, year: 2016 https://www.sciencedirect.com/science/article/pii/S0921509317308535

The Mechanism of Russian Nanoindustry Development Caused by Globalization: Methods and Tools

Directory of Open Access Journals (Sweden)

Avtonomova Oksana Alekseevna

2015-05-01

Full Text Available Establishing the effective mechanism of the Russian nanoindustry functioning by means of globalization benefits is one of the most important factors of raising the national economy competitiveness in the context of transition to a new technological way. Nanotechnologies is one of the key factors of this new way. The mechanism of nanoindustrial development of the Russian Federation caused by globalization is characterized in the article as a way of task-oriented implementation and management of the global nanotechnology industry development on the basis of cooperation of entities at different levels of the global economic system using the appropriate methods, tools, resources and communication channels, factors and capitals. The mechanism aims at adjusting the described contradictions faced by Russian entities in their business activities in the sphere of production, consumption and promotion of nanotechnologies, nanogoods and nanoservices. Within the framework of a theoretical research the author proposes the classification of methods and tools for the development of the Russian nanoindustry through the international cooperation by the criteria of economic functions: planning, institution, organization, management, investment, finance, information, analysis, control – all aimed at promoting the unification of concepts and actions of collaborating entities in the sphere of nanotechnology. The developed methodology of the international nanoindustrial interaction of Russian entities includes the result-oriented, institutional, organizational, budgetary, investment, tax, informative, and administrative methods, as well as analysis, audit, accounting and evaluation. Besides, the article proves the feasibility of marketing tools application in the sphere of nanoindustrial cooperation aimed at developing a more efficient strategy of promoting products with nanofeatures to the global market.

Mechanical Resonators for Material Characterization: Sensor Development and Applications

DEFF Research Database (Denmark)

Casci Ceccacci, Andrea; Bosco, Filippo Giacomo

The goals of this PhD project were to provide new approaches and developing new systems for material characterization, based on micro and nanomechanical sensors. Common issues that have shown to hinder large-scale integration of sensing techniques based on a micromechanical sensor are the readout......-co-Glycolic Acid (PLGA), which is of high relevance in the biomedical research field. A second version of the system is currently under development, and it aims to increase the throughput of the system allowing to read out multiple microbridge arrays. For material characterization, spectroscopy analysis is often...... considered a benchmark technology. Conventional infrared spectroscopy approaches commonly require milligram amount of sample. Considering the frame of reference given by the overall aim of the project, mechanical sensors can be exploited to provide a unique tool for performing spectroscopy on a limited...

Mechanics of Nanostructures: Methods and Results

Science.gov (United States)

Ruoff, Rod

2003-03-01

We continue to develop and use new tools to measure the mechanics and electromechanics of nanostructures. Here we discuss: (a) methods for making nanoclamps and the resulting: nanoclamp geometry, chemical composition and type of chemical bonding, and nanoclamp strength (effectiveness as a nanoclamp for the mechanics measurements to be made); (b) mechanics of carbon nanocoils. We have received carbon nanocoils from colleagues in Japan [1], measured their spring constants, and have observed extensions exceeding 100% relative to the unloaded length, using our scanning electron microscope nanomanipulator tool; (c) several new devices that are essentially MEMS-based, that allow for improved measurements of the mechanics of psuedo-1D and planar nanostructures. [1] Zhang M., Nakayama Y., Pan L., Japanese J. Appl. Phys. 39, L1242-L1244 (2000).

Investigation of methods for fabricating, characterizing, and transporting cryogenic inertial-confinement-fusion tartets

Energy Technology Data Exchange (ETDEWEB)

Fanning, J.J.; Kim, K.

1981-01-01

The objective of this work is to investigate methods for fabricating, characterizing and transporting cryogenic inertial confinement fusion targets on a continuous basis. A microprocessor-based data acquisition system has been built that converts a complete target image to digital data, which are then analyzed by automated software procedures. The low temperatures required to freeze the hydrogen isotopes contained in a target is provided by a cryogenic cold chamber capable of attaining 15 K. A new method for target manipulation and positioning is studied that employs molecular gas beams to levitate a target and an electrostatic quadrupole structure to provide for its lateral containment. Since the electrostatic target-positioning scheme requires that the targets be charged, preliminary investigation has been carried out for a target-charging mechanism based on ion-bombardment.

Investigation of methods for fabricating, characterizing, and transporting cryogenic inertial-confinement-fusion tartets

International Nuclear Information System (INIS)

Fanning, J.J.; Kim, K.

1981-01-01

The objective of this work is to investigate methods for fabricating, characterizing and transporting cryogenic inertial confinement fusion targets on a continuous basis. A microprocessor-based data acquisition system has been built that converts a complete target image to digital data, which are then analyzed by automated software procedures. The low temperatures required to freeze the hydrogen isotopes contained in a target is provided by a cryogenic cold chamber capable of attaining 15 K. A new method for target manipulation and positioning is studied that employs molecular gas beams to levitate a target and an electrostatic quadrupole structure to provide for its lateral containment. Since the electrostatic target-positioning scheme requires that the targets be charged, preliminary investigation has been carried out for a target-charging mechanism based on ion-bombardment

Statistical-mechanical entropy by the thin-layer method

International Nuclear Information System (INIS)

Feng, He; Kim, Sung Won

2003-01-01

G. Hooft first studied the statistical-mechanical entropy of a scalar field in a Schwarzschild black hole background by the brick-wall method and hinted that the statistical-mechanical entropy is the statistical origin of the Bekenstein-Hawking entropy of the black hole. However, according to our viewpoint, the statistical-mechanical entropy is only a quantum correction to the Bekenstein-Hawking entropy of the black-hole. The brick-wall method based on thermal equilibrium at a large scale cannot be applied to the cases out of equilibrium such as a nonstationary black hole. The statistical-mechanical entropy of a scalar field in a nonstationary black hole background is calculated by the thin-layer method. The condition of local equilibrium near the horizon of the black hole is used as a working postulate and is maintained for a black hole which evaporates slowly enough and whose mass is far greater than the Planck mass. The statistical-mechanical entropy is also proportional to the area of the black hole horizon. The difference from the stationary black hole is that the result relies on a time-dependent cutoff

Analytical Methods for Biomass Characterization during Pretreatment and Bioconversion

Energy Technology Data Exchange (ETDEWEB)

Pu, Yunqiao [ORNL; Meng, Xianzhi [University of Tennessee, Knoxville (UTK); Yoo, Chang Geun; Li, Mi; Ragauskas, Arthur J [ORNL

2016-01-01

Lignocellulosic biomass has been introduced as a promising resource for alternative fuels and chemicals because of its abundance and complement for petroleum resources. Biomass is a complex biopolymer and its compositional and structural characteristics largely vary depending on its species as well as growth environments. Because of complexity and variety of biomass, understanding its physicochemical characteristics is a key for effective biomass utilization. Characterization of biomass does not only provide critical information of biomass during pretreatment and bioconversion, but also give valuable insights on how to utilize the biomass. For better understanding biomass characteristics, good grasp and proper selection of analytical methods are necessary. This chapter introduces existing analytical approaches that are widely employed for biomass characterization during biomass pretreatment and conversion process. Diverse analytical methods using Fourier transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), and nuclear magnetic resonance (NMR) spectroscopy for biomass characterization are reviewed. In addition, biomass accessibility methods by analyzing surface properties of biomass are also summarized in this chapter.

The characterization methods for colloids in aqueous solutions

International Nuclear Information System (INIS)

Vuorinen, U.; Kumpulainen, H.

1993-11-01

This literature review deals with characterization methods for colloids in aqueous solutions and in groundwater. The basis for the review has been the needs of nuclear waste disposal studies and methods applicable in such studies. The methods considered include non-destructive laserspectroscopic methods (e.g. TRLFS, LPAS, PALS), several separation methods (e.g. ultrafiltration, dialysis, electrophoresis, field-flow-fractionation) and also some surface analytical methods, as well as some other methods giving additional information on formation and migration properties of colloids. (au.) (71 refs., 13 figs., 3 tabs.)

Methods for Characterization of Batteries Using Acoustic Interrogation

Science.gov (United States)

Bhadra, Shoham

Batteries are a ubiquitous form of electrochemical energy storage, but thus far the methods for measuring the mechanical properties of batteries and their component materials in operando have lagged far behind the methods for measuring the corresponding electrical properties. In this thesis, I demonstrate methods for determining the changes in materials properties of an electrochemical energy storage cell both ex situ and in operando.. I begin by establishing the impact of micro-scale morphology changes on the macro-scale dynamic mechanical response in commercial alkaline AA cells. Using a bounce test, the coefficient of restitution (COR) of the cell is shown to increase non-linearly as a function of state of charge (SOC). I show that the reason for the increase in the COR stems from the spatially-dependent oxidation of the Zn anode, with an initial increase corresponding to the formation of a percolation pathway of ZnO-clad Zn particles spanning the radius of the anode. The subsequent saturation of the COR is shown to result from the ultimate solidification and desiccation of the Zn anode. Building from this, I present a generalized in operando solution for materials characterization in batteries using ultrasonic interrogation. The materials properties of battery components change during charge and discharge, resulting in a change in the sound speed of the materials. By attaching transducers to a battery during cycling and sending ultrasonic pulses through each cell I observe the changes in the time of flight (ToF) of the pulses, both in reflection and transmission. I show that the changes in ToF correspond to both SOC and state of health (SOH) in a variety of battery chemistries and geometries, and detail a corresponding acoustic conservation law model framework. Finally, I perform these electrochemical acoustic time of flight (EAToF) experiments on commercial alkaline AA cells. By correlating the results with energy dispersive x-ray diffraction (EDXRD) data and

Characterization of Thermal and Mechanical Impact on Aluminum Honeycomb Structures

Science.gov (United States)

Robinson, Christen M.

2013-01-01

This study supports NASA Kennedy Space Center's research in the area of intelligent thermal management systems and multifunctional thermal systems. This project addresses the evaluation of the mechanical and thermal properties of metallic cellular solid (MCS) materials; those that are lightweight; high strength, tunable, multifunctional and affordable. A portion of the work includes understanding the mechanical properties of honeycomb structured cellular solids upon impact testing under ambient, water-immersed, liquid nitrogen-cooled, and liquid nitrogen-immersed conditions. Additionally, this study will address characterization techniques of the aluminum honeycomb's ability to resist multiple high-rate loadings or impacts in varying environmental conditions, using various techniques for the quantitative and qualitative determination for commercial applicability.

Morphological and mechanical characterization of chitosan-calcium phosphate composites for potential application as bone-graft substitutes

Directory of Open Access Journals (Sweden)

Guilherme Maia Mulder van de Graaf

Full Text Available Introduction: Bone diseases, aging and traumas can cause bone loss and lead to bone defects. Treatment of bone defects is challenging, requiring chirurgical procedures. Bone grafts are widely used for bone replacement, but they are limited and expensive. Due to bone graft limitations, natural, semi-synthetic, synthetic and composite materials have been studied as potential bone-graft substitutes. Desirable characteristics of bone-graft substitutes are high osteoinductive and angiogenic potentials, biological safety, biodegradability, bone-like mechanical properties, and reasonable cost. Herein, we prepared and characterized potential bone-graft substitutes composed of calcium phosphate (CP - a component of natural bone, and chitosan (CS - a biocompatible biopolymer. Methods CP-CS composites were synthetized, molded, dried and characterized. The effect of drying temperatures (38 and 60 °C on the morphology, porosity and chemical composition of the composites was evaluated. As well, the effects of drying temperature and period of drying (3, 24, 48 and 72 hours on the mechanical properties - compressive strength, modulus of elasticity and relative deformation-of the demolded samples were investigated. Results Scanning electron microscopy and gas adsorption-desorption analyses of the CS-CP composites showed interconnected pores, indicating that the drying temperature played an important role on pores size and distribution. In addition, drying temperature have altered the color (brownish at 60 °C due to Maillard reaction and the chemical composition of the samples, confirmed by FTIR. Conclusion Particularly, prolonged period of drying have improved mechanical properties of the CS-CP composites dried at 38 °C, which can be designed according to the mechanical needs of the replaceable bone.

Upgraded Features of Newly Constructed Fuel Assembly Mechanical Characterization Test Facility in KAERI

Energy Technology Data Exchange (ETDEWEB)

Lee, Kang Hee; Kang, Heung Seok; Yoon, Kyung Ho; Kim, Hyung Kyu; Lee, Young Ho; Kim, Soo Ho; Yang, Jae Ho [KAERI, Daejeon (Korea, Republic of)

2016-05-15

Fuel assembly mechanical characterization test facility (FAMeCT) in KAERI is newly constructed with upgraded functional features such as increased loading capacity, under-water vibration testing and severe earthquake simulation for extended fuel design guideline. The facility building is compactly designed in the scale of 3rd floor building and has regions for assembly-wise mechanical test equipment, dynamic load (seismic) simulating test system, small scale hydraulic loop and component wise test equipment. Figure 1 shows schematic regional layout of the facility building. Mechanical test platform and system is designed to increase loading capacity for axial compression test. Structural stability of the support system of new upper core plate simulator is validated through a limit case functional test. Fuel assembly mechanical characterization test facility in KAERI is newly constructed and upgraded with advanced functional features such as uprated loading capacity, under-water vibration testing and severe earthquake simulation for extended fuel design guideline. This paper briefly introduce the test facility construction and scope of the facility and is focused on the upgraded design features of the facility. Authors hope to facilitate the facility more in the future and collaborate with the industry.

Characterization of tissue biomechanics and mechanical signaling in uterine leiomyoma☆

Science.gov (United States)

Norian, John M.; Owen, Carter M.; Taboas, Juan; Korecki, Casey; Tuan, Rocky; Malik, Minnie; Catherino, William H.; Segars, James H.

2012-01-01

Leiomyoma are common tumors arising within the uterus that feature excessive deposition of a stiff, disordered extracellular matrix (ECM). Mechanical stress is a critical determinant of excessive ECM deposition and increased mechanical stress has been shown to be involved in tumorigenesis. Here we tested the viscoelastic properties of leiomyoma and characterized dynamic and static mechanical signaling in leiomyoma cells using three approaches, including measurement of active RhoA. We found that the peak strain and pseudo-dynamic modulus of leiomyoma tissue was significantly increased relative to matched myometrium. In addition, leiomyoma cells demonstrated an attenuated response to applied cyclic uniaxial strain and to variation in substrate stiffness, relative to myometrial cells. However, on a flexible pronectin-coated silicone substrate, basal levels and lysophosphatidic acid-stimulated levels of activated RhoA were similar between leiomyoma and myometrial cells. In contrast, leiomyoma cells plated on a rigid polystyrene substrate had elevated levels of active RhoA, compared to myometrial cells. The results indicate that viscoelastic properties of the ECM of leiomyoma contribute significantly to the tumor’s inherent stiffness and that leiomyoma cells have an attenuated sensitivity to mechanical cues. The findings suggest there may be a fundamental alteration in the communication between the external mechanical environment (extracellular forces) and reorganization of the actin cytoskeleton mediated by RhoA in leiomyoma cells. Additional research will be needed to elucidate the mechanism(s) responsible for the attenuated mechanical signaling in leiomyoma cells. PMID:21983114

New test and characterization methods for PV modules and cells

Energy Technology Data Exchange (ETDEWEB)

Van Aken, B.; Sommeling, P. [ECN Solar Energy, Petten (Netherlands); Scholten, H. [Solland, Heerlen (Netherlands); Muller, J. [Moser-Baer, Eindhoven (Netherlands); Grossiord, N. [Holst Centre, Eindhoven (Netherlands); Smits, C.; Blanco Mantecon, M. [Holland Innovative, Eindhoven (Netherlands); Verheijen, M.; Van Berkum, J. [Philips Innovation Services, Eindhoven (Netherlands)

2012-08-15

The results of the project geZONd (shared facility for solar module analysis and reliability testing) are described. The project was set up by Philips, ECN, Holst, Solland, OM and T and Holland Innovative. The partners have shared most of their testing and analysis equipment for PV modules and cells, and together developed new or improved methods (including the necessary application know-how). This enables faster and more efficient innovation projects for each partner, and via commercial exploitation for other interested parties. The project has concentrated on five failure modes: corrosion, delamination, moisture ingress, UV irradiation, and mechanical bending. Test samples represented all main PV technologies: wafer based PV and rigid and flexible thin-film PV. Breakthroughs are in very early detection of corrosion, in quantitative characterization of adhesion, in-situ detection of humidity and oxygen inside modules, and ultra-fast screening of materials on UV stability.

Radiometric method for the characterization of particulate processes in colloidal suspensions. II. Experimental verification of the method

Energy Technology Data Exchange (ETDEWEB)

Subotic, B. [Institut Rudjer Boskovic, Zagreb (Yugoslavia)

1979-09-15

A radiometric method for the characterization of particulate processes is verified using stable hydrosols of silver iodide. Silver iodide hydrosols satisfy the conditions required for the applications of the proposed method. Comparison shows that the values for the change of particle size measured in silver iodide hydrosols by the proposed method are in excellent agreement with the values obtained by other methods on the same systems (electron microscopy, sedimentation analysis, light scattering). This shows that the proposed method is suitable for the characterization of particulate processes in colloidal suspensions. (Auth.).

Molecular mechanism of apoptosis and characterization of apoptosis induced by radiation

International Nuclear Information System (INIS)

Li Yumin; Zhang Yuguang; Li Yukun

1999-01-01

The major discoveries of apoptosis research in recent years were reviewed briefly. The mechanisms of caspases/ICE gene family and bcl-2 gene family on apoptosis were analyzed. And the signal transduction pathway of apoptosis found currently has been summarized. The characterizations of apoptosis induced by radiation such as time-effects, dose-effects and the radiosensibility were summed up

Nonequilibrium statistical mechanics ensemble method

CERN Document Server

Eu, Byung Chan

1998-01-01

In this monograph, nonequilibrium statistical mechanics is developed by means of ensemble methods on the basis of the Boltzmann equation, the generic Boltzmann equations for classical and quantum dilute gases, and a generalised Boltzmann equation for dense simple fluids The theories are developed in forms parallel with the equilibrium Gibbs ensemble theory in a way fully consistent with the laws of thermodynamics The generalised hydrodynamics equations are the integral part of the theory and describe the evolution of macroscopic processes in accordance with the laws of thermodynamics of systems far removed from equilibrium Audience This book will be of interest to researchers in the fields of statistical mechanics, condensed matter physics, gas dynamics, fluid dynamics, rheology, irreversible thermodynamics and nonequilibrium phenomena

Wear mechanisms of dental composite restorative materials by two different in-vitro methods

Directory of Open Access Journals (Sweden)

Juliana Antonino de Souza

2013-04-01

Full Text Available In this work two very simple apparatuses, namely the ball crater (or ball-on-plate and the linear reciprocating (or pin-on-plate tests, were used in order to investigate the wear mechanisms of TPH Spectrum® and Resilab Master® dental composite resins. Loads in the range of 100 g to 1 kg and a total number of up to 24000 cycles were employed. During some of these tests, aqueous aluminum oxide suspensions were used as abrasive agent either diluted or not in distilled water. In case of the ball-on-plate test wear is dominated by abrasive and/or adhesive mechanisms, and is characterized by scratches which are composed of wear defects comprising particle detachment, wear of the polymer matrix and ceramic particle abrasion. However, the relative contributions of the two wear mechanisms could not be determined separately. In case of the pin-on-plate test wear is governed by the fatigue mechanism, although abrasive and adhesive wear mechanism are also present. After a certain number of cycles fatigue wear dominates the wear behavior and results in severe material loss. This mechanism seems to be more important in case of more brittle materials and when higher loads are employed. Qualitative analysis of the results suggests that the combination of these two very simple methods under appropriate conditions can yield sound results which may be representative of a number of clinical situations.

Wear mechanisms of dental composite restorative materials by two different in-vitro methods

Directory of Open Access Journals (Sweden)

Juliana Antonino de Souza

2012-01-01

Full Text Available In this work two very simple apparatuses, namely the ball crater (or ball-on-plate and the linear reciprocating (or pin-on-plate tests, were used in order to investigate the wear mechanisms of TPH Spectrum® and Resilab Master® dental composite resins. Loads in the range of 100 g to 1 kg and a total number of up to 24000 cycles were employed. During some of these tests, aqueous aluminum oxide suspensions were used as abrasive agent either diluted or not in distilled water. In case of the ball-on-plate test wear is dominated by abrasive and/or adhesive mechanisms, and is characterized by scratches which are composed of wear defects comprising particle detachment, wear of the polymer matrix and ceramic particle abrasion. However, the relative contributions of the two wear mechanisms could not be determined separately. In case of the pin-on-plate test wear is governed by the fatigue mechanism, although abrasive and adhesive wear mechanism are also present. After a certain number of cycles fatigue wear dominates the wear behavior and results in severe material loss. This mechanism seems to be more important in case of more brittle materials and when higher loads are employed. Qualitative analysis of the results suggests that the combination of these two very simple methods under appropriate conditions can yield sound results which may be representative of a number of clinical situations.

Recent Advances on In Situ SEM Mechanical and Electrical Characterization of Low-Dimensional Nanomaterials.

Science.gov (United States)

Jiang, Chenchen; Lu, Haojian; Zhang, Hongti; Shen, Yajing; Lu, Yang

2017-01-01

In the past decades, in situ scanning electron microscopy (SEM) has become a powerful technique for the experimental study of low-dimensional (1D/2D) nanomaterials, since it can provide unprecedented details for individual nanostructures upon mechanical and electrical stimulus and thus uncover the fundamental deformation and failure mechanisms for their device applications. In this overview, we summarized recent developments on in situ SEM-based mechanical and electrical characterization techniques including tensile, compression, bending, and electrical property probing on individual nanostructures, as well as the state-of-the-art electromechanical coupling analysis. In addition, the advantages and disadvantages of in situ SEM tests were also discussed with some possible solutions to address the challenges. Furthermore, critical challenges were also discussed for the development and design of robust in situ SEM characterization platform with higher resolution and wider range of samples. These experimental efforts have offered in-depth understanding on the mechanical and electrical properties of low-dimensional nanomaterial components and given guidelines for their further structural and functional applications.

Recent Advances on In Situ SEM Mechanical and Electrical Characterization of Low-Dimensional Nanomaterials

Directory of Open Access Journals (Sweden)

Chenchen Jiang

2017-01-01

Full Text Available In the past decades, in situ scanning electron microscopy (SEM has become a powerful technique for the experimental study of low-dimensional (1D/2D nanomaterials, since it can provide unprecedented details for individual nanostructures upon mechanical and electrical stimulus and thus uncover the fundamental deformation and failure mechanisms for their device applications. In this overview, we summarized recent developments on in situ SEM-based mechanical and electrical characterization techniques including tensile, compression, bending, and electrical property probing on individual nanostructures, as well as the state-of-the-art electromechanical coupling analysis. In addition, the advantages and disadvantages of in situ SEM tests were also discussed with some possible solutions to address the challenges. Furthermore, critical challenges were also discussed for the development and design of robust in situ SEM characterization platform with higher resolution and wider range of samples. These experimental efforts have offered in-depth understanding on the mechanical and electrical properties of low-dimensional nanomaterial components and given guidelines for their further structural and functional applications.

Task-Based Method for Designing Underactuated Mechanisms

Directory of Open Access Journals (Sweden)

Shoichiro Kamada

2012-03-01

Full Text Available In this paper we introduce a task-based method for designing underactuated multi-joint prosthetic hands for specific grasping tasks. The designed robotic hands or prosthetic hands contain fewer independent actuators than joints. We chose a few specific grasping tasks that are frequently repeated in everyday life and analysed joint motions of the hand during the completion of each task and the level of participation of each joint. The information was used for the synthesis of dedicated underactuated mechanisms that can operate in a low dimensional task coordinate space. We propose two methods for reducing the actuators' number. The kinematic parameters of the synthesized mechanism are determined by using a numerical approach. In this study the joint angles of the synthesized hand are considered as linearly dependent on the displacements of the actuators. We introduced a special error index that allowed us to compare the original trajectory and the trajectory performed by the synthesized mechanism, and to select the kinematic parameters of the new kinematic structure as a way to reduce the error. The approach allows the design of simple gripper mechanisms with good accuracy for the preliminary defined tasks.

Mechanical characterization of epoxy composite with multiscale reinforcements: Carbon nanotubes and short carbon fibers

International Nuclear Information System (INIS)

Rahmanian, S.; Suraya, A.R.; Shazed, M.A.; Zahari, R.; Zainudin, E.S.

2014-01-01

Highlights: • Multiscale composite was prepared by incorporation of carbon nanotubes and fibers. • Carbon nanotubes were also grown on short carbon fibers to enhance stress transfer. • Significant improvements were achieved in mechanical properties of composites. • Synergic effect of carbon nanotubes and fibers was demonstrated. - Abstract: Carbon nanotubes (CNT) and short carbon fibers were incorporated into an epoxy matrix to fabricate a high performance multiscale composite. To improve the stress transfer between epoxy and carbon fibers, CNT were also grown on fibers through chemical vapor deposition (CVD) method to produce CNT grown short carbon fibers (CSCF). Mechanical characterization of composites was performed to investigate the synergy effects of CNT and CSCF in the epoxy matrix. The multiscale composites revealed significant improvement in elastic and storage modulus, strength as well as impact resistance in comparison to CNT–epoxy or CSCF–epoxy composites. An optimum content of CNT was found which provided the maximum stiffness and strength. The synergic reinforcing effects of combined fillers were analyzed on the fracture surface of composites through optical and scanning electron microscopy (SEM)

The development and mechanical characterization of aluminium copper-carbon fiber metal matrix hybrid composite

Science.gov (United States)

Manzoor, M. U.; Feroze, M.; Ahmad, T.; Kamran, M.; Butt, M. T. Z.

2018-04-01

Metal matrix composites (MMCs) come under advanced materials that can be used for a wide range of industrial applications. MMCs contain a non-metallic reinforcement incorporated into a metallic matrix which can enhance properties over base metal alloys. Copper-Carbon fiber reinforced aluminium based hybrid composites were prepared by compo casting method. 4 weight % copper was used as alloying element with Al because of its precipitation hardened properties. Different weight compositions of composites were developed and characterized by mechanical testing. A significant improvement in tensile strength and micro hardness were found, before and after heat treatment of the composite. The SEM analysis of the fractured surfaces showed dispersed and embedded Carbon fibers within the network leading to the enhanced strength.

Characterization of esophageal physiology using mechanical state analysis

Directory of Open Access Journals (Sweden)

Richard Eduard Leibbrandt

2016-02-01

Full Text Available The esophagus functions to transport swallowed fluids and food from the pharynx to the stomach. The esophageal muscles governing bolus transport comprise circular striated muscle of the proximal esophagus and circular smooth muscle of the distal esophagus. Longitudinal smooth muscle contraction provides a mechanical advantage to bolus transit during circular smooth muscle contraction. Esophageal striated muscle is directly controlled by neural circuits originating in the central nervous system, resulting in coordinated contractions. In contrast, the esophageal smooth muscle is controlled by enteric circuits modulated by extrinsic central neural connections resulting in neural relaxation and contraction. The esophageal muscles are modulated by sensory information arising from within the lumen. Contraction or relaxation, which changes the diameter of the lumen, alters the intraluminal pressure and ultimately inhibits or promotes flow of content. This relationship that exists between the changes in diameter and concurrent changes in intraluminal pressure has been used previously to identify the ‘mechanical states’ of the circular muscle; that is when the muscles are passively or actively, relaxing or contracting. Detecting these changes in the mechanical state of the muscle has been difficult and, as the current interpretation of esophageal motility is based largely upon pressure measurement (manometry, subtle changes in the muscle function during peristalsis can be missed. We hypothesized that quantification of mechanical states of the esophageal circular muscles and the pressure-diameter properties that define them, would allow objective characterization of the mechanisms that govern esophageal peristalsis. To achieve this we analyzed barium swallows captured by simultaneous videofluoroscopy and pressure with impedance recording. From these data we demonstrated that intraluminal impedance measurements could be used to determine changes in the

Characterization of Esophageal Physiology Using Mechanical State Analysis.

Science.gov (United States)

Leibbrandt, Richard E; Dinning, Phil G; Costa, Marcello; Cock, Charles; Wiklendt, Lukasz; Wang, Guangsong; Tack, Jan; van Beckevoort, Dirk; Rommel, Nathalie; Omari, Taher I

2016-01-01

The esophagus functions to transport swallowed fluids and food from the pharynx to the stomach. The esophageal muscles governing bolus transport comprise circular striated muscle of the proximal esophagus and circular smooth muscle of the distal esophagus. Longitudinal smooth muscle contraction provides a mechanical advantage to bolus transit during circular smooth muscle contraction. Esophageal striated muscle is directly controlled by neural circuits originating in the central nervous system, resulting in coordinated contractions. In contrast, the esophageal smooth muscle is controlled by enteric circuits modulated by extrinsic central neural connections resulting in neural relaxation and contraction. The esophageal muscles are modulated by sensory information arising from within the lumen. Contraction or relaxation, which changes the diameter of the lumen, alters the intraluminal pressure and ultimately inhibits or promotes flow of content. This relationship that exists between the changes in diameter and concurrent changes in intraluminal pressure has been used previously to identify the "mechanical states" of the circular muscle; that is when the muscles are passively or actively, relaxing or contracting. Detecting these changes in the mechanical state of the muscle has been difficult and as the current interpretation of esophageal motility is based largely upon pressure measurement (manometry), subtle changes in the muscle function during peristalsis can be missed. We hypothesized that quantification of mechanical states of the esophageal circular muscles and the pressure-diameter properties that define them, would allow objective characterization of the mechanisms that govern esophageal peristalsis. To achieve this we analyzed barium swallows captured by simultaneous videofluoroscopy and pressure with impedance recording. From these data we demonstrated that intraluminal impedance measurements could be used to determine changes in the internal diameter of

Method For Producing Mechanically Flexible Silicon Substrate

KAUST Repository

Hussain, Muhammad Mustafa

2014-08-28

A method for making a mechanically flexible silicon substrate is disclosed. In one embodiment, the method includes providing a silicon substrate. The method further includes forming a first etch stop layer in the silicon substrate and forming a second etch stop layer in the silicon substrate. The method also includes forming one or more trenches over the first etch stop layer and the second etch stop layer. The method further includes removing the silicon substrate between the first etch stop layer and the second etch stop layer.

Method For Producing Mechanically Flexible Silicon Substrate

KAUST Repository

Hussain, Muhammad Mustafa; Rojas, Jhonathan Prieto

2014-01-01

A method for making a mechanically flexible silicon substrate is disclosed. In one embodiment, the method includes providing a silicon substrate. The method further includes forming a first etch stop layer in the silicon substrate and forming a second etch stop layer in the silicon substrate. The method also includes forming one or more trenches over the first etch stop layer and the second etch stop layer. The method further includes removing the silicon substrate between the first etch stop layer and the second etch stop layer.

ASTM test methods for composite characterization and evaluation

Science.gov (United States)

Masters, John E.

1994-01-01

A discussion of the American Society for Testing and Materials is given. Under the topic of composite materials characterization and evaluation, general industry practice and test methods for textile composites are presented.

Fabrication and Mechanical Characterization of Hydrogel Infused Network Silk Scaffolds

Directory of Open Access Journals (Sweden)

Lakshminath Kundanati

2016-09-01

Full Text Available Development and characterization of porous scaffolds for tissue engineering and regenerative medicine is of great importance. In recent times, silk scaffolds were developed and successfully tested in tissue engineering and drug release applications. We developed a novel composite scaffold by mechanical infusion of silk hydrogel matrix into a highly porous network silk scaffold. The mechanical behaviour of these scaffolds was thoroughly examined for their possible use in load bearing applications. Firstly, unconfined compression experiments show that the denser composite scaffolds displayed significant enhancement in the elastic modulus as compared to either of the components. This effect was examined and further explained with the help of foam mechanics principles. Secondly, results from confined compression experiments that resemble loading of cartilage in confinement, showed nonlinear material responses for all scaffolds. Finally, the confined creep experiments were performed to calculate the hydraulic permeability of the scaffolds using soil mechanics principles. Our results show that composite scaffolds with some modifications can be a potential candidate for use of cartilage like applications. We hope such approaches help in developing novel scaffolds for tissue engineering by providing an understanding of the mechanics and can further be used to develop graded scaffolds by targeted infusion in specific regions.

Numerical methods in dynamic fracture mechanics

International Nuclear Information System (INIS)

Beskos, D.E.

1987-01-01

A review of numerical methods for the solution of dynamic problems of fracture mechanics is presented. Finite difference, finite element and boundary element methods as applied to linear elastic or viscoelastic and non-linear elastoplastic or elastoviscoplastic dynamic fracture mechanics problems are described and critically evaluated. Both cases of stationary cracks and rapidly propagating cracks of simple I, II, III or mixed modes are considered. Harmonically varying with time or general transient dynamic disturbances in the form of external loading or incident waves are taken into account. Determination of the dynamic stress intensity factor for stationary cracks or moving cracks with known velocity history as well as determination of the crack-tip propagation history for given dynamic fracture toughness versus crack velocity relation are described and illustrated by means of certain representative examples. Finally, a brief assessment of the present state of knowledge is made and research needs are identified

Microstructural and mechanical characterization of Al–Zn–Si nanocomposites

Energy Technology Data Exchange (ETDEWEB)

García-Villarreal, S. [Centro de Investigación en Materiales Avanzados S.C. Monterrey, 66600, Alianza Nte. 202, Parque PIIT, Apodaca, N.L. (Mexico); Chávez-Valdez, A. [Katcon Institute for Innovation and Technology KIIT, 66629, Alianza Sur 200, Apodaca, N.L. (Mexico); Moreno, K.J. [Instituto Tecnológico de Celaya, Apartado Postal 57, 38010 Celaya, Guanajuato (Mexico); Leyva, C.; Aguilar-Martínez, J.A. [Centro de Investigación en Materiales Avanzados S.C. Monterrey, 66600, Alianza Nte. 202, Parque PIIT, Apodaca, N.L. (Mexico); Hurtado, A. [Centro de Investigación en Materiales Avanzados S.C., 31109, Miguel de Cervantes 120, Chih., Chih. (Mexico); Arizmendi-Morquecho, A., E-mail: ana.arizmendi@cimav.edu.mx [Centro de Investigación en Materiales Avanzados S.C. Monterrey, 66600, Alianza Nte. 202, Parque PIIT, Apodaca, N.L. (Mexico)

2013-09-15

In this paper the addition of silicon nanoparticles into Al–Zn alloys to form metallic matrix nanocomposites by mechanical alloying process was investigated. The influence of various process parameters such as milling time and Si concentration in the Al–Zn matrix has an interesting effect on the microstructure and mechanical properties of the synthesized nanocomposites. The microstructural characterization of the nanocomposites was evaluated by transmission electron microscopy and energy dispersive X-ray spectroscopy (TEM–EDXS) and the mechanical properties were measured by nanoindentation and micro-hardness tests. The results showed that during mechanical milling Si is added to the Al–Zn matrix achieving a uniform and homogeneous dispersion. After solidification, it forms small particles of AlZnSi with blocky morphology in interdendritic regions. The nanoindentation profiles showed that the elastic modulus and hardness properties increase with increasing milling time. However, a high concentration of Si (> 1.2 wt.%) results in a saturation of Si in the Al–Zn matrix, which adversely affects the mechanical properties. Thus, it is important to tune the milling time and concentration of Si added to the Al–Zn alloys to control the growth of brittle phases that result in reduction of the mechanical properties of the material. - Highlights: • A novel technique for addition of Si nanocomposites into Al–Zn liquid alloy is reported. • Good dispersion and homogeneity of Si in the Al–Zn matrix are obtained. • Increasing Si content above 1.2 wt.% decreases the mechanical properties of Al–Zn alloy. • The saturation point of Si in 1.2 wt.% differs from Galvalume® composition. • The Al–Zn–1.5Si alloy with addition of nanocomposite shows 5.7 GPa of hardness.

EBSD characterization of the growth mechanism of SiC synthesized via direct microwave heating

Energy Technology Data Exchange (ETDEWEB)

Wang, Jigang, E-mail: wangjigang@seu.edu.cn [Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China); Xizang Key Laboratory of Optical Information Processing and Visualization Technology, School of Information Engineering, Xizang Minzu University, Xianyang 712082 (China); Huang, Shan; Liu, Song; Qing, Zhou [Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China)

2016-04-15

Well-crystallized 3C-silicon carbide (SiC) grains/nanowires have been synthesized rapidly and conveniently via direct microwave heating, simply using silicon dioxide powders and artificial graphite as raw materials. The comprehensive characterizations have been employed to investigate the micro-structure of the obtained 3C-SiC products. Results indicated that, different from the classic screw dislocation growth mechanism, the 3C-SiC grains/nanowires synthesized via high-energy vacuum microwave irradiation were achieved through the two-dimension nucleation and laminar growth mechanism. Especially, the electron backscattered diffraction (EBSD) was employed to characterize the crystal planes of the as-grown SiC products. The calculated Euler angles suggested that the fastest-growing crystal planes (211) were overlapped gradually. Through the formation of the (421) transformation plane, (211) finally evolved to (220) which existed as the side face of SiC grains. The most stable crystal planes (111) became the regular hexagonal planes in the end, which could be explained by the Bravais rule. The characterization results of EBSD provided important experimental information for the evolution of crystal planes. - Graphical abstract: The formation of 3C-SiC prepared via direct microwave heating follows the mechanism of two-dimension nucleation and laminar growth. - Highlights: • 3C−SiC grains/nanowires were obtained via direct microwave heating. • 3C−SiC followed the mechanism of two-dimension nucleation and laminar growth. • In-situ EBSD analysis provided the experimental evidences of the growth.

Comparison of three different scales techniques for the dynamic mechanical characterization of two polymers (PDMS and SU8)

Science.gov (United States)

Le Rouzic, J.; Delobelle, P.; Vairac, P.; Cretin, B.

2009-10-01

In this article the dynamic mechanical characterization of PDMS and SU8 resin using dynamic mechanical analysis, nanoindentation and the scanning microdeformation microscope have been presented. The methods are hereby explained, extended for viscoelastic behaviours, and their compatibility underlined. The storage and loss moduli of these polymers over a wide range of frequencies (from 0.01 Hz to somekHz) have been measured. These techniques are shown fairly matching and the two different viscoelastic behaviours of these two polymers have been exhibited. Indeed, PDMS shows moduli which still increase at 5kHz whereas SU8 ones decrease much sooner. From a material point of view, the Havriliak and Negami model to estimate instantaneous, relaxed moduli and time constant of these materials has been identified.

Characterization of Al–Al{sub 4}C{sub 3} nanocomposites produced by mechanical milling

Energy Technology Data Exchange (ETDEWEB)

Santos-Beltrán, A., E-mail: asantos@utchsur.edu.mx [Universidad Tecnológica de Chihuahua Sur, Carr. Chihuahua a Aldama km. 3 S/N, Col. Colinas del León, CP. 31313 Chihuahua, Chih. (Mexico); Goytia-Reyes, R. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes No. 120, C.P. 31109 Chihuahua, Chih. (Mexico); Morales-Rodriguez, H.; Gallegos-Orozco, V. [Universidad Tecnológica de Chihuahua Sur, Carr. Chihuahua a Aldama km. 3 S/N, Col. Colinas del León, CP. 31313 Chihuahua, Chih. (Mexico); Santos-Beltrán, M. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes No. 120, C.P. 31109 Chihuahua, Chih. (Mexico); Baldenebro-Lopez, F. [Universidad Tecnológica de Chihuahua Sur, Carr. Chihuahua a Aldama km. 3 S/N, Col. Colinas del León, CP. 31313 Chihuahua, Chih. (Mexico); Martínez-Sánchez, R. [Centro de Investigación en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnología, Miguel de Cervantes No. 120, C.P. 31109 Chihuahua, Chih. (Mexico)

2015-08-15

In this work, a mixture of Al–C–Al{sub 4}C{sub 3} nanopowder previously synthesized by mechanical milling and subsequent thermal treatment was used to reinforce the Al matrix. The nanocomposites were fabricated via high-energy ball milling and subsequent sintering process for different periods of time at 550 °C. Hardness and compression tests were performed to evaluate the mechanical properties of the nanocomposites in the as-milled and sintered conditions. According to the results the reinforcement located in the grain boundaries is responsible for the brittle behavior observed in the nanocomposites during the compression test. The combined effect of sintering and precipitation mechanisms produced an evident increase of the strength of the Al matrix at a relatively short sintering time. By using the Rietveld method the crystallite size and microstrain measurements were determined and correlated with the microhardness values. For the proper characterization of the nanoparticles present in the Al matrix, atomic force microscopy and high resolution electron microscopy were used. - Highlights: • Nanostructured Al{sub 4}C{sub 3} reinforcement was fabricated via mechanical milling and heat treatment. • We found a significant increase of the mechanical properties at short sintering times. • The formation of Al{sub 4}C{sub 3} with during sintering time restricted the excessive growth of the crystallite. • Al{sub 4}C{sub 3} located in the grain boundaries causes brittle fracture observed in compression tests. • There is a correlation between, crystallite size and microstrain values with microhardness.

Mining Host-Pathogen Protein Interactions to Characterize Burkholderia mallei Infectivity Mechanisms

Science.gov (United States)

2015-03-04

the cytoskeleton, in lysosomes , and in the nuclear lumen. These results were consistent with the experimentally observed pathogen interference with...RESEARCH ARTICLE Mining Host- Pathogen Protein Interactions to Characterize Burkholderia mallei Infectivity Mechanisms Vesna Memišević1, Nela...Bacteriology Division, U.S. Army Medical Research Institute of Infectious Diseases , Fort Detrick, Maryland, United States of America * jaques.reifman.civ

Microstructural characterization of titanium dental implants by electron microscopy and mechanical tests

International Nuclear Information System (INIS)

Helfenstein, B.; Muniz, N.O.; Dedavid, B.A.; Gehrke, S.A.; Vargas, A.L.M.

2010-01-01

Mini screw types for titanium implants, with differentiated design, were tested for traction and torsion for behavior analysis of the shape relative to the requirements of ASTM F136. All implants showed mechanical tensile strength above by the standard requirement, being that 83.3% of them broke above the doughnut, in support of the prosthesis. Distinct morphologies in ruptured by mechanical tests, were obtained. However, both fracture surfaces showed fragile comportments. Metallographic tests, x-ray diffraction (XRD) and microhardness were used for microstructural characterization of material, before and after heat treatment. The presences of β phase in screw surface after quenching treatment proves that the thermal treatment can contribute for mechanical resistance in surface implants. (author)

Hydroxyapatite nanocrystals: simple preparation, characterization and formation mechanism.

Science.gov (United States)

Mohandes, Fatemeh; Salavati-Niasari, Masoud; Fathi, Mohammadhossein; Fereshteh, Zeinab

2014-12-01

Crystalline hydroxyapatite (HAP) nanoparticles and nanorods have been successfully synthesized via a simple precipitation method. To control the shape and particle size of HAP nanocrystals, coordination ligands derived from 2-hydroxy-1-naphthaldehyde were first prepared, characterized by Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance ((1)H-NMR) spectroscopies, and finally applied in the synthesis process of HAP. On the other hand, the HAP nanocrystals were also characterized by several techniques including powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). According to the FE-SEM and TEM micrographs, it was found that the morphology and crystallinity of the HAP powders depended on the coordination mode of the ligands. Copyright © 2014 Elsevier B.V. All rights reserved.

Technologies and methods used for the detection, enrichment and characterization of cancer stem cells.

Science.gov (United States)

Williams, Anthony; Datar, Ram; Cote, Richard

2010-01-01

Cancer stem cells (CSCs) represent a subclass of tumour cells with the ability for self-renewal, production of differentiated progeny, prolonged survival, resistance to damaging therapeutic agents, and anchorage-independent survival, which together make this population effectively equipped to metastasize, invade and colonize secondary tissues in the face of therapeutic intervention. In recent years, investigators have increasingly focused on the characterization of CSCs to better understand the mechanisms that govern malignant disease progression in an effort to develop more effective, targeted therapeutic agents. The primary obstacle to the study of CSCs, however, is their rarity. Thus, the study of CSCs requires the use of sensitive and efficient technologies for their enrichment and detection. This review discusses technologies and methods that have been adapted and used to isolate and characterize CSCs to date, as well as new potential directions for the enhanced enrichment and detection of CSCs. While the technologies used for CSC enrichment and detection have been useful thus far for their characterization, each approach is not without limitations. Future studies of CSCs will depend on the enhanced sensitivity and specificity of currently available technologies, and the development of novel technologies for increased detection and enrichment of CSCs.

Electrical and mechanical characterization of nanoscale-layered cellulose-based electro-active paper.

Science.gov (United States)

Yun, Gyu-Young; Yun, Ki-Ju; Kim, Joo-Hyung; Kim, Jaehwan

2011-01-01

In order to understand the electro-mechanical behavior of piezoelectric electro active paper (EAPap), the converse and direct piezoelectric characterization of cellulose EAPap was studied and compared. A delay between the electrical field and the induced strain of EAPap was observed due to the inner nano-voids or the localized amorphous regions in layer-by-layered structure to capture or hold the electrical charges and remnant ions. The linear relation between electric field and induced strain is also observed. The electro-mechanical performance of EAPap is discussed in detail in this paper.

A simple method for generating exactly solvable quantum mechanical potentials

CERN Document Server

Williams, B W

1993-01-01

A simple transformation method permitting the generation of exactly solvable quantum mechanical potentials from special functions solving second-order differential equations is reviewed. This method is applied to Gegenbauer polynomials to generate an attractive radial potential. The relationship of this method to the determination of supersymmetric quantum mechanical superpotentials is discussed, and the superpotential for the radial potential is also derived. (author)

A Novel Method of Mechanical Oxidation of CNT for Polymer Nanocomposite Application: Evaluation of Mechanical, Dynamic Mechanical, and Rheological Properties

Directory of Open Access Journals (Sweden)

Priyanka Pandey

2014-01-01

Full Text Available A new approach of oxidation of carbon nanotubes has been used to oxidize the CNTs. A comparative aspect of the mechanical oxidation and acid oxidation process has been established. FTIR analysis and titration method have shown the higher feasibility of the mechanical oxidation method to oxidize the CNTs. Comparatively less damage to the CNTs has been observed in case of mechanically oxidized as compared to acid oxidized CNTs. The mechanical properties of the nanocomposites reinforced with the acid oxidized CNT (ACNT and mechanically oxidized CNTs (McCNT were analyzed and relatively higher properties in the nanocomposites reinforced with McCNT were noticed. The less degree of entanglement in the McCNTs was noticed as compared to ACNTs. The dynamic mechanical analysis of the nanocomposites revealed much improved load transfer capability in the McCNT reinforced composites. Further, the rheological properties of the nanocomposites revealed the higher performance of McCNT reinforced composites.

Methods of stability analysis in nonlinear mechanics

International Nuclear Information System (INIS)

Warnock, R.L.; Ruth, R.D.; Gabella, W.; Ecklund, K.

1989-01-01

We review our recent work on methods to study stability in nonlinear mechanics, especially for the problems of particle accelerators, and compare our ideals to those of other authors. We emphasize methods that (1) show promise as practical design tools, (2) are effective when the nonlinearity is large, and (3) have a strong theoretical basis. 24 refs., 2 figs., 2 tabs

Mechanic-electrical transformations in the Kelvin method

Energy Technology Data Exchange (ETDEWEB)

Zharkikh, Yu. S., E-mail: yurzhar@gmail.com [Faculty of Radio Physics, Electronics and Computer Systems, Taras Shevchenko National University of Kyiv, 4G, Ave. Academician Glushkov, 03127, Kyiv (Ukraine); Lysochenko, S.V., E-mail: lys@univ.kiev.ua [Institute of High Technologies, Taras Shevchenko National University of Kyiv, 4G, Ave. Academician Glushkov, 03127, Kyiv (Ukraine)

2017-04-01

Highlights: • Used in Kelvin method dynamic capacitor is a mechanic-electrical transformer. • The oscillations of its plate are source of extraneous forces which cause the appearance of an electric current. • The signal is caused not by the contact potential difference, but by oscillation in the screening conditions of charge in the dynamic capacitor gap. • Combining the Kelvin method with electron emission methods to determine the work function may lead to incorrectness. - Abstract: To explain the initiation mechanism of alternating current in an electric circuit containing the dynamic capacitor a model of mechanic- electrical transformation is suggested to use. In such a model, electric charges disposed between the capacitor plates serve as a cause of measured signal in contrast to the contact potential difference, which is considered as the main base in the Kelvin’s model. If one of the plates moves periodically, then the conditions of the charges screening are changed and thereby the capacitor recharging current is arise. The measuring is based on compensation of the recharging current by current, which generated by a source of electromotive force (EMF). The compensation voltage depends on both the distribution of ions or dipoles over the studied surface and the charges creating the surface potential barrier. This voltage is independent on the bulk electro-physical characteristics of a solid.

Methods of characterization of multiphase Nd-Fe-B melt-spun alloys

Directory of Open Access Journals (Sweden)

Grujić A.

2007-01-01

Full Text Available Nanocomposite permanent magnetic materials based on Nd-Fe-B alloys with a low Nd content are a new type of permanent magnetic material. The microstructure of these nanocomposite permanent magnets is composed of a mixture of magnetically soft and hard phases providing the so called exchange coupling effect. Beside the optimization process parameters, methods of characterization have a very important role in the design of an optimal magnetic matrix of multiphase melt-spun Nd-Fe-B alloys. Different methods and techniques of characterization were used for observation and study of the microstructure evolution during crystallization. A summary results of measurements using different methods of characterization are presented to enable a better insight into relations between the microstructure and magnetic properties of the investigated melt-spun Nd-Fe-B alloys. .

Characterization of nitride hole lateral transport in a charge trap flash memory by using a random telegraph signal method

Science.gov (United States)

Liu, Yu-Heng; Jiang, Cheng-Min; Lin, Hsiao-Yi; Wang, Tahui; Tsai, Wen-Jer; Lu, Tao-Cheng; Chen, Kuang-Chao; Lu, Chih-Yuan

2017-07-01

We use a random telegraph signal method to investigate nitride trapped hole lateral transport in a charge trap flash memory. The concept of this method is to utilize an interface oxide trap and its associated random telegraph signal as an internal probe to detect a local channel potential change resulting from nitride charge lateral movement. We apply different voltages to the drain of a memory cell and vary a bake temperature in retention to study the electric field and temperature dependence of hole lateral movement in a nitride. Thermal energy absorption by trapped holes in lateral transport is characterized. Mechanisms of hole lateral transport in retention are investigated. From the measured and modeled results, we find that thermally assisted trap-to-band tunneling is a major trapped hole emission mechanism in nitride hole lateral transport.

Improvement of mechanical properties of polymeric composites: Experimental methods and new systems

Science.gov (United States)

Nguyen, Felix Nhanchau

Filler- (e.g., particulate or fiber) reinforced structural polymers or polymeric composites have changed the way things are made. Today, they are found, for example, in air/ground transportation vehicles, sporting goods, ballistic barrier applications and weapons, electronic packaging, musical instruments, fashion items, and more. As the demand increases, so does the desire to have not only well balanced mechanical properties, but also light weight and low cost. This leads to a constant search for novel constituents and additives, new fabrication methods and analytical techniques. To achieve new or improved composite materials requires more than the identification of the right reinforcements to be used with the right polymer matrix at the right loading. Also, an optimized adhesion between the two phases and a toughened matrix system are needed. This calls for new methods to predict, modify and assess the level of adhesion, and new developments in matrix tougheners to minimize compromises in other mechanical/thermal properties. Furthermore, structural optimization, associated with fabrication (e.g., avoidance of fiber-fiber touching or particle aggregation), and sometimes special properties, such as electrical conductivity or magnetic susceptibility are necessary. Finally, the composite system's durability, often under hostile conditions, is generally mandatory. The present study researches new predictive and experimental methods for optimizing and characterizing filler-matrix adhesion and develops a new type of epoxy tougheners. Specifically, (1) a simple thermodynamic parameter evaluated by UNIFAC is applied successfully to screen out candidate adhesion promoters, which is necessary for optimization of the physio-chemical interactions between the two phases; (2) an optical-acoustical mechanical test assisted with an acoustic emission technique is developed to de-convolute filler debonding/delamination among many other micro failure events, and (3) novel core

Classification of analysis methods for characterization of magnetic nanoparticle properties

DEFF Research Database (Denmark)

Posth, O.; Hansen, Mikkel Fougt; Steinhoff, U.

2015-01-01

The aim of this paper is to provide a roadmap for the standardization of magnetic nanoparticle (MNP) characterization. We have assessed common MNP analysis techniques under various criteria in order to define the methods that can be used as either standard techniques for magnetic particle...... characterization or those that can be used to obtain a comprehensive picture of a MNP system. This classification is the first step on the way to develop standards for nanoparticle characterization....

Structural characterization and mechanical properties of polypropylene reinforced natural fibers

Science.gov (United States)

Karim, M. A. A.; Zaman, I.; Rozlan, S. A. M.; Berhanuddin, N. I. C.; Manshoor, B.; Mustapha, M. S.; Khalid, A.; Chan, S. W.

2017-10-01

Recently the development of natural fiber composite instead of synthetics fiber has lead to eco-friendly product manufacturing to meet various applications in the field of automotive, construction and manufacturing. The use of natural fibers offer an alternative to the reinforcing fibers because of their good mechanical properties, low density, renewability, and biodegradability. In this present research, the effects of maleic anhydride polypropylene (MAPP) on the mechanical properties and material characterization behaviour of kenaf fiber and coir fiber reinforced polypropylene were investigated. Different fractions of composites with 10wt%, 20wt% and 30wt% fiber content were prepared by using brabender mixer at 190°C. The 3wt% MAPP was added during the mixing. The composites were subsequently molded with injection molding to prepare the test specimens. The mechanical properties of the samples were investigated according to ISO 527 to determine the tensile strength and modulus. These results were also confirmed by the SEM machine observations of fracture surface of composites and FTIR analysis of the chemical structure. As the results, the presence of MAPP helps increasing the mechanical properties of both fibers and 30wt% kenaf fiber with 3wt% MAPP gives the best result compare to others.

Mathematical methods for mechanics a handbook with Matlab experiments

CERN Document Server

Gekeler, Eckart W

2008-01-01

This book introduces all the mathematical tools necessary for solving complex problems in the field of mechanics. It also contains various applications of mathematical and numerical methods for modeling comprehensive mechanical-technical practical problems.

Fabrication and mechanical characterization of a polyvinyl alcohol sponge for tissue engineering applications.

Science.gov (United States)

Karimi, A; Navidbakhsh, M; Faghihi, S

2014-05-01

Polyvinyl alcohol (PVA) sponges are widely used for clinical applications, including ophthalmic surgical treatments, wound healing and tissue engineering. There is, however, a lack of sufficient data on the mechanical properties of PVA sponges. In this study, a biomechanical method is used to characterize the elastic modulus, maximum stress and strain as well as the swelling ratio of a fabricated PVA sponge (P-sponge) and it is compared with two commercially available PVA sponges (CENEFOM and EYETEC). The results indicate that the elastic modulus of the P-sponge is 5.32% and 13.45% lower than that of the CENEFOM and EYETEC sponges, while it bears 4.11% more and 10.37% less stress compared to the CENEFOM and EYETEC sponges, respectively. The P-sponge shows a maximum strain of 32% more than the EYETEC sponge as well as a 26.78% higher swelling ratio, which is a significantly higher absorbency compared to the CENEFOM. It is believed that the results of this study would help for a better understanding of the extension, rupture and swelling mechanism of PVA sponges, which could lead to crucial improvement in the design and application of PVA-based materials in ophthalmic and plastic surgeries as well as wound healing and tissue engineering.

A multiscale quantum mechanics/electromagnetics method for device simulations.

Science.gov (United States)

Yam, ChiYung; Meng, Lingyi; Zhang, Yu; Chen, GuanHua

2015-04-07

Multiscale modeling has become a popular tool for research applying to different areas including materials science, microelectronics, biology, chemistry, etc. In this tutorial review, we describe a newly developed multiscale computational method, incorporating quantum mechanics into electronic device modeling with the electromagnetic environment included through classical electrodynamics. In the quantum mechanics/electromagnetics (QM/EM) method, the regions of the system where active electron scattering processes take place are treated quantum mechanically, while the surroundings are described by Maxwell's equations and a semiclassical drift-diffusion model. The QM model and the EM model are solved, respectively, in different regions of the system in a self-consistent manner. Potential distributions and current densities at the interface between QM and EM regions are employed as the boundary conditions for the quantum mechanical and electromagnetic simulations, respectively. The method is illustrated in the simulation of several realistic systems. In the case of junctionless field-effect transistors, transfer characteristics are obtained and a good agreement between experiments and simulations is achieved. Optical properties of a tandem photovoltaic cell are studied and the simulations demonstrate that multiple QM regions are coupled through the classical EM model. Finally, the study of a carbon nanotube-based molecular device shows the accuracy and efficiency of the QM/EM method.

Characterization of parameters and strategies used by physical therapists in difficult mechanical ventilation weaning

Directory of Open Access Journals (Sweden)

Fabíola Maria Sabino Meireles

2013-03-01

Full Text Available Objective: To characterize the main strategies and parameters used by physical therapists in difficult mechanical ventilation weaning. Methods: Cross-sectional study including all the physical therapists working in adult Intensive Care Units in three public hospitals in Fortaleza-CE. A questionnaire with closed questions related to difficult mechanical ventilation weaning was applied, with either one or multiple answers. The data was treated with descriptive and non-parametric analysis. Results: Among the parameters mostly used by the 56 interviewed physical therapists for the difficult weaning, were found: current volume reduction (26 - 46.4% and desaturation during aspiration (17 - 30.4%. It was observed that 38 (67.9% alternate T-tube and continuous positive airway pressure (CPAP as strategies for difficult weaning, and 28 (50% reported reducing the pressure support. There was no statistical difference between the strategies used in the studied hospitals, neither correlation between strategies and parameters. Conclusion: It was found that physical therapists have been performing similar strategies, which are also shown in the literature, but this is not the case with the parameters. The parameters used are not supported by the literature.

A method for characterizing photon radiation fields

International Nuclear Information System (INIS)

Whicker, J.J.; Hsu, H.H.; Hsieh, F.H.; Borak, T.B.

1999-01-01

Uncertainty in dosimetric and exposure rate measurements can increase in areas where multi-directional and low-energy photons (< 100 keV) exist because of variations in energy and angular measurement response. Also, accurate measurement of external exposures in spatially non-uniform fields may require multiple dosimetry. Therefore, knowledge of the photon fields in the workplace is required for full understanding of the accuracy of dosimeters and instruments, and for determining the need for multiple dosimeters. This project was designed to develop methods to characterize photon radiation fields in the workplace, and to test the methods in a plutonium facility. The photon field at selected work locations was characterized using TLDs and a collimated NaI(Tl) detector from which spatial variations in photon energy distributions were calculated from measured spectra. Laboratory results showed the accuracy and utility of the method. Field measurement results combined with observed work patterns suggested the following: (1) workers are exposed from all directions, but not isotropically, (2) photon energy distributions were directionally dependent, (3) stuffing nearby gloves into the glovebox reduced exposure rates significantly, (4) dosimeter placement on the front of the chest provided for a reasonable estimate of the average dose equivalent to workers' torsos, (5) justifiable conclusions regarding the need for multiple dosimetry can be made using this quantitative method, and (6) measurements of the exposure rates with ionization chambers pointed with open beta windows toward the glovebox provided the highest measured rates, although absolute accuracy of the field measurements still needs to be assessed

Electrical Impedance Spectroscopy for Electro-Mechanical Characterization of Conductive Fabrics

Directory of Open Access Journals (Sweden)

Tushar Kanti Bera

2014-06-01

Full Text Available When we use a conductive fabric as a pressure sensor, it is necessary to quantitatively understand its electromechanical property related with the applied pressure. We investigated electromechanical properties of three different conductive fabrics using the electrical impedance spectroscopy (EIS. We found that their electrical impedance spectra depend not only on the electrical properties of the conductive yarns, but also on their weaving structures. When we apply a mechanical tension or compression, there occur structural deformations in the conductive fabrics altering their apparent electrical impedance spectra. For a stretchable conductive fabric, the impedance magnitude increased or decreased under tension or compression, respectively. For an almost non-stretchable conductive fabric, both tension and compression resulted in decreased impedance values since the applied tension failed to elongate the fabric. To measure both tension and compression separately, it is desirable to use a stretchable conductive fabric. For any conductive fabric chosen as a pressure-sensing material, its resistivity under no loading conditions must be carefully chosen since it determines a measurable range of the impedance values subject to different amounts of loadings. We suggest the EIS method to characterize the electromechanical property of a conductive fabric in designing a thin and flexible fabric pressure sensor.

VISCOSE BASED MAGNETIC YARNS – PHYSICAL AND MECHANICAL CHARACTERIZATION

Directory of Open Access Journals (Sweden)

GROSU Marian-Cătălin

2017-05-01

Full Text Available In the context of the rapid growth in the number of electrical and electronic devices and accessories that emit electromagnetic energy in different frequency bands we present and characterize here several magnetic functionalized viscose twisted yarns. A 100% viscose twisted staple yarn was covered through an in-house developed process with a polymeric solution containing micrometric sized barium hexaferrite magnetic powder. The in-house developed process allows deposition of micrometric thickness polymeric paste layer on the yarn surface. Barium hexaferrite is a hard magnetic material exhibiting high chemical stability and corrosion resistivity, relatively large saturation and residual magnetization and microwave absorbing properties. Five different percentages of the magnetic powder in the polymer solution were used, i.e. ranging from 15 wt% to 45 wt%. Physical characterization shows a very good adherence between the highly hygroscopic viscose staple fibers and the polymeric solution that contains polyvinyl acetate and polyurethane as binders. SEM images evidenced the fact that the polymeric solution penetrated more than 1/3 of the yarn diameter. The concentration of magnetic powder in the polymeric solution has a direct influence on the coating amount, diameter and density. The mechanical characterization of the coated yarns revealed that the breaking force is increasing with increasing magnetic powder content up to o certain value and then decreased because the magnetic layer became stiffer. At the same time, the elongation at brake is decreasing.

Structural, mechanical and electrical characterization of epoxy-amine/carbon black nanonocomposites

Directory of Open Access Journals (Sweden)

2008-05-01

Full Text Available This work presents an insight into the effect of preparation procedure and the filler content on both electrical and mechanical properties of a nanocomposite system. For the preparation of the nanocomposites diglycidyl ether of bisphenol A (DGEBA was used with triethylenetetramine (TETA as a curing agent. As fillers carbon black (CB nanoparticles with size from 25 to 75 nm were used. The characterization was done using Dynamic Mechanical Analysis (DMA, Dielectric Relaxation Spectroscopy (DRS, Differential Scanning Calorimetry (DSC, Wide Angle X-ray Diffraction (WAXD and electrical conductivity measurements. The dependence of the dynamic mechanical and dielectric parameters (E′, E″, tanδ, ε', ε″, σ and Tg is associated with the filler content and is controlled by the employed curing conditions. An increase in electrical conductivity, which is observed at about 1% w/w of carbon black, indicates the creation of conducting paths and is associated with the Maxwell Wagner Sillars (MWS relaxation, probably due to the formation of aggregated microstructures in the bulk composite..

Nondestructive techniques for characterizing mechanical properties of structural materials: An overview

Science.gov (United States)

Vary, A.; Klima, S. J.

1985-01-01

An overview of nondestructive evaluation (NDE) is presented to indicate the availability and application potentials of techniques for quantitative characterization of the mechanical properties of structural materials. The purpose is to review NDE techniques that go beyond the usual emphasis on flaw detection and characterization. Discussed are current and emerging NDE techniques that can verify and monitor entrinsic properties (e.g., tensile, shear, and yield strengths; fracture toughness, hardness, ductility; elastic moduli) and underlying microstructural and morphological factors. Most of the techniques described are, at present, neither widely applied nor widely accepted in commerce and industry because they are still emerging from the laboratory. The limitations of the techniques may be overcome by advances in applications research and instrumentation technology and perhaps by accommodations for their use in the design of structural parts.

Mechanics, Models and Methods in Civil Engineering

CERN Document Server

Maceri, Franco

2012-01-01

„Mechanics, Models and Methods in Civil Engineering” collects leading papers dealing with actual Civil Engineering problems. The approach is in the line of the Italian-French school and therefore deeply couples mechanics and mathematics creating new predictive theories, enhancing clarity in understanding, and improving effectiveness in applications. The authors of the contributions collected here belong to the Lagrange Laboratory, an European Research Network active since many years. This book will be of a major interest for the reader aware of modern Civil Engineering.

Synthesis and characterization of TiO2 nanoparticles by the method Pechini

International Nuclear Information System (INIS)

Zoccal, Joao Victor Marques; Arouca, Fabio de Oliveira; Goncalves, Jose Antonio Silveira

2009-01-01

In recent years, scientific research showed an increasing interest in the field of nanotechnology, resulting in several techniques for the production of nanoparticles, such as methods of chemical synthesis. Among the various existing methods, the Pechini method has been used to obtain nanoparticles of titanium dioxide (TiO 2 ). Thus, this work aims to synthesize and characterize nanoparticles of TiO 2 obtained by this method. The technique constitutes in the reaction between citric acid with titanium isopropoxide, resulting as the product the titanium citrate. With the addition of the ethylene glycol polymerization occurs, resulting in a polymeric resin. At the end of the process, the resin is calcined to remove organic matter, creating nanoparticles of TiO 2 . The resulting powders were characterized by thermogravimetric analysis (TGA) and thermal differential analysis (DTA), X-ray diffraction, absorption spectrophotometry in the infrared, method of adsorption nitrogen / helium (BET method) and scanning electron microscopy. The results obtained in the characterization techniques showed that the Pechini method is promising in obtaining nanosized TiO 2 . (author)

Thermomechanical characterization of thiol-epoxy shape memory thermosets for mechanical actuators design

Science.gov (United States)

Belmonte, Alberto; Fernández-Francos, Xavier; De la Flor, Silvia

2018-02-01

In this paper, shape-memory "thiol-epoxy" polymers are synthesized and characterized as potential thermomechanical actuators. Their thermomechanical properties are investigated through dynamo mechanical and tensile analyses and related to their network structural properties by using "thiol" and "epoxy" compounds of different functionality and structure. Their mechanical properties (resistance at break, elongation limits and strain energy) are related to their shape-memory response under free-recovery conditions and partially-constrained conditions, thus, establishing the connection between network relaxation (free-recovery) with the work output capabilities (partially-constrained). Results show high mechanical performance, achieving high elongation at break values (up to 100%) and stress at break values (up to 50 MPa). The shape-memory experiments reveal strong dependence of the programming conditions and network structure on the recovery efficiency at free-conditions, whereas under partially-constrained conditions, the controlling factors are the mechanical limits at high temperature. Moreover, some recommendations to achieve the maximum work output efficiency for a given operational design of a thermomechanical actuator are deduced.

Preparation and characterization of strontium-fluorapatite nanopowders by sol-gel method

Science.gov (United States)

Kamaei, Maryam; Fathi, Mohammad Hossein

2018-01-01

Biomaterials based on calcium orthophosphate are especially attractive for use in medicine, for bone and teeth implants due to their biological properties, such as biocompatibility and bioactivity. Among them, hydroxyapatite (HAP; Ca10(PO4)6(OH)2) is used particularly because of its similarities to the inorganic component of bone. Hydroxyapatite has been widely used for biomedical applications. Despite desirable properties such as bioactivity, biocompatibility, solubility and adsorption, synthetic HA is limited in application due to poor thermostability and poor mechanical properties. Properties of HA can be tailored over a wide range by incorporating different ions into HA lattice. Use of the sol-gel technique is technically simple, cost effective and beneficial for fabrication biomaterials. This research aimed to prepare and characterize Sr-doped FA nanopowders (Sr-FA). Sr-FA with different Sr contents was prepared by sol-gel method. The designated degree of substitution of Ca by Sr in the mixture was determined by the x value in the general formula of (Ca10-x Srx(PO4)6F2), where x=0,0.5,1. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques were utilized to characterize the obtained nano powders. Results showed that Sr ions entered into the fluorapatite lattice and occupied Ca sites. The incorporation of Sr ions into the fluorapatite resulted in the increase of the lattice parameters.

Second GAMM-conference on numerical methods in fluid mechanics

International Nuclear Information System (INIS)

Hirschel, E.H.; Geller, W.

1977-01-01

Proceedings of the Second GAMM-Conference on Numerical Methods in Fluid Mechanics held at the DFVLR, Koeln, October 11 to 13, 1977. The conference was attended by approximately 100 participants from 13 European countries representing quite different fields ranging from Aerodynamics to Nuclear Energy. At the meeting 34 papers were presented, many of them concerned with basic problems in the field. It was well demonstrated that Numerical Methods in Fluid Mechanics do not only serve as means for the computation of flow fields but also as tools in the analysis of fluid mechanical phenomena, a role of large future importance if one considers the complexity especially of three-dimensional flows. (orig./RW) [de

Characterization of an electroactive polymer simultaneously driven by an electrical field and a mechanical excitation: An easy means of measuring the dielectric constant, the Young modulus and the electrostrictive coefficients

Energy Technology Data Exchange (ETDEWEB)

Guyomar, Daniel [Universite de Lyon, LGEF-INSA de Lyon, Batiment Gustave Ferrie, 8 rue de la Physique, 69621 Villeurbanne Cedex (France); Cottinet, Pierre-Jean, E-mail: Pierre-jean.cottinet@insa-lyon.f [Universite de Lyon, LGEF-INSA de Lyon, Batiment Gustave Ferrie, 8 rue de la Physique, 69621 Villeurbanne Cedex (France); Lebrun, Laurent; Sebald, Gael [Universite de Lyon, LGEF-INSA de Lyon, Batiment Gustave Ferrie, 8 rue de la Physique, 69621 Villeurbanne Cedex (France)

2011-04-18

An easy method for measuring the dielectric constant, the Young modulus and the electrostrictive coefficients of a polymer film is proposed herein. The approach was based on the determination of the current flowing through the sample when simultaneously driven by an electrical field and a mechanical excitation. The experimental data were in good agreement with published results. In addition, the method rendered it possible to characterize the film sample under real conditions. - Highlights: In this study we model a multiphysic coupling in electroactive polymer (EAP). A new method was developed to determine the different coefficient of the material. The results demonstrated the potential of this method for the characterization of EAP.

Computational performance of Free Mesh Method applied to continuum mechanics problems

Science.gov (United States)

YAGAWA, Genki

2011-01-01

The free mesh method (FMM) is a kind of the meshless methods intended for particle-like finite element analysis of problems that are difficult to handle using global mesh generation, or a node-based finite element method that employs a local mesh generation technique and a node-by-node algorithm. The aim of the present paper is to review some unique numerical solutions of fluid and solid mechanics by employing FMM as well as the Enriched Free Mesh Method (EFMM), which is a new version of FMM, including compressible flow and sounding mechanism in air-reed instruments as applications to fluid mechanics, and automatic remeshing for slow crack growth, dynamic behavior of solid as well as large-scale Eigen-frequency of engine block as applications to solid mechanics. PMID:21558753

Mechanical Characterization of Mancos Shale

Science.gov (United States)

Broome, S.; Ingraham, M. D.; Dewers, T. A.

2015-12-01

A series of tests on Mancos shale have been undertaken to determine the failure surface and to characterize anisotropy. This work supports additional studies which are being performed on the same block of shale; fracture toughness, permeability, and chemical analysis. Mechanical tests are being conducted after specimens were conditioned for at least two weeks at 70% constant relative humidity conditions. Specimens are tested under drained conditions, with the constant relative humidity condition maintained on the downstream side of the specimen. The upstream is sealed. Anisotropy is determined through testing specimens that have been cored parallel and perpendicular to the bedding plane. Preliminary results show that when loaded parallel to bedding the shale is roughly 50% weaker. Test are run under constant mean stress conditions when possible (excepting indirect tension, unconfined compression, and hydrostatic). Tests are run in hydrostatic compaction to the desired mean stress, then differential stress is applied axially in displacement control to failure. The constant mean stress condition is maintained by decreasing the confining pressure by half of the increase in the axial stress. Results will be compared to typical failure criteria to investigate the effectiveness of capturing the behavior of the shale with traditional failure theory. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND2015-6107 A.

Methods to characterize non-Gaussian noise in TAMA

International Nuclear Information System (INIS)

Ando, Masaki; Arai, K; Takahashi, R; Tatsumi, D; Beyersdorf, P; Kawamura, S; Miyoki, S; Mio, N; Moriwaki, S; Numata, K; Kanda, N; Aso, Y; Fujimoto, M-K; Tsubono, K; Kuroda, K

2003-01-01

We present a data characterization method for the main output signal of the interferometric gravitational-wave detector, in particular targeting at effective detection of burst gravitational waves from stellar core collapse. The time scale of non-Gaussian events is evaluated in this method, and events with longer time scale than real signals are rejected as non-Gaussian noises. As a result of data analysis using 1000 h of real data with the interferometric gravitational-wave detector TAMA300, the false-alarm rate was improved 10 3 times with this non-Gaussian noise evaluation and rejection method

Characterization of Unbound Granular Materials for Pavements

NARCIS (Netherlands)

Araya, A.A.

2011-01-01

This research is focused on the characterization of the mechanical behavior of unbound granular road base materials (UGMs). An extensive laboratory investigation is described, in which various methods for determination of the mechanical properties of granular materials are examined for their

Characterization of molecularly imprinted polymers using a new polar solvent titration method.

Science.gov (United States)

Song, Di; Zhang, Yagang; Geer, Michael F; Shimizu, Ken D

2014-07-01

A new method of characterizing molecularly imprinted polymers (MIPs) was developed and tested, which provides a more accurate means of identifying and measuring the molecular imprinting effect. In the new polar solvent titration method, a series of imprinted and non-imprinted polymers were prepared in solutions containing increasing concentrations of a polar solvent. The polar solvent additives systematically disrupted the templation and monomer aggregation processes in the prepolymerization solutions, and the extent of disruption was captured by the polymerization process. The changes in binding capacity within each series of polymers were measured, providing a quantitative assessment of the templation and monomer aggregation processes in the imprinted and non-imprinted polymers. The new method was tested using three different diphenyl phosphate imprinted polymers made using three different urea functional monomers. Each monomer had varying efficiencies of templation and monomer aggregation. The new MIP characterization method was found to have several advantages. To independently verify the new characterization method, the MIPs were also characterized using traditional binding isotherm analyses. The two methods appeared to give consistent conclusions. First, the polar solvent titration method is less susceptible to false positives in identifying the imprinting effect. Second, the method is able to differentiate and quantify changes in binding capacity, as measured at a fixed guest and polymer concentration, arising from templation or monomer aggregation processes in the prepolymerization solution. Third, the method was also easy to carry out, taking advantage of the ease of preparing MIPs. Copyright © 2014 John Wiley & Sons, Ltd.

Mechanical characterization of bucky gel morphing nanocomposite for actuating/sensing applications

International Nuclear Information System (INIS)

Ghamsari, Ali Kadkhoda; Woldesenbet, Eyassu; Jin, Yoonyoung

2012-01-01

Since the demonstration of the bucky gel actuator (BGA) in 2005, a great deal of effort has been exerted to develop novel applications for this electro-active morphing nanocomposite. This three-layered bimorph nanocomposite can be easily fabricated, operated in air and driven with a few volts. The BGA with improved mechanical strength is an excellent candidate for application in macro- to micro-scale smart structures with actuating and sensing capabilities. However, developing new applications requires identifying and understanding the effective design parameters and mechanical properties, respectively. There has been limited published studies on the mechanical properties of BGA. In this study, the effect of three parameters—layer thickness, carbon nanotube type and weight fraction of components—on the mechanical properties was investigated. Samples were characterized via nano-indentation and DMA. The BGA composed of 22 wt% single-walled carbon nanotubes and 45 wt% ionic liquid exhibited the highest hardness, adhesion, viscosity, and elastic and storage moduli. This study revealed the important role of the carbon nanotube type on BGA adhesion. Samples made with multi-walled carbon nanotubes had the lowest adhesion, which is a required factor in applications such as microfluidics. (paper)

Assessing learning outcomes in middle-division classical mechanics: The Colorado Classical Mechanics and Math Methods Instrument

Science.gov (United States)

Caballero, Marcos D.; Doughty, Leanne; Turnbull, Anna M.; Pepper, Rachel E.; Pollock, Steven J.

2017-06-01

Reliable and validated assessments of introductory physics have been instrumental in driving curricular and pedagogical reforms that lead to improved student learning. As part of an effort to systematically improve our sophomore-level classical mechanics and math methods course (CM 1) at CU Boulder, we have developed a tool to assess student learning of CM 1 concepts in the upper division. The Colorado Classical Mechanics and Math Methods Instrument (CCMI) builds on faculty consensus learning goals and systematic observations of student difficulties. The result is a 9-question open-ended post test that probes student learning in the first half of a two-semester classical mechanics and math methods sequence. In this paper, we describe the design and development of this instrument, its validation, and measurements made in classes at CU Boulder and elsewhere.

Operator methods in quantum mechanics

CERN Document Server

Schechter, Martin

2003-01-01

This advanced undergraduate and graduate-level text introduces the power of operator theory as a tool in the study of quantum mechanics, assuming only a working knowledge of advanced calculus and no background in physics. The author presents a few simple postulates describing quantum theory, gradually introducing the mathematical techniques that help answer questions important to the physical theory; in this way, readers see clearly the purpose of the method and understand the accomplishment. The entire book is devoted to the study of a single particle moving along a straight line. By posing q

Identification, characterization and quantification of new impurities by LC-ESI/MS/MS and LC-UV methods in rivastigmine tartrate active pharmaceutical ingredient.

Science.gov (United States)

Thomas, Saji; Shandilya, Sanjeev; Bharati, Amber; Paul, Saroj Kumar; Agarwal, Ashutosh; Mathela, Chandra S

2012-01-05

Six impurities were detected at trace level in rivastigmine tartrate drug substance by a newly developed high performance liquid chromatography method. Three impurities were characterized rapidly and three impurities were found to be unknown. The unknown impurities were enriched and identified with a combination of semi-preparative HPLC and LC/MS/MS techniques. Proposed structures were further confirmed by characterization using NMR, FT-IR, and EA techniques of impurity standards. Based on the spectroscopic, spectrometric and elemental analysis data unknown impurities were characterized as 3-[1-(dimethylamino)ethyl]phenyl N-ethyl-N-methyl carbamate N-oxide, ethyl-methyl-carbamic acid 4-(1-dimethylamino-ethyl)-phenyl ester and ethyl-methyl-carbamic acid 2-(1-dimethylamino-ethyl)-phenyl ester. A plausible mechanism for the formation of these impurities is also proposed. The method was validated according to ICH guidelines for fourteen impurities to demonstrate specificity, precision, linearity, accuracy and stability indicating nature of the method. Regression analysis showed correlation coefficient value greater than 0.999 for rivastigmine tartrate and its impurities. Accuracy of the method was established based on the recovery obtained between 93.41 and 113.33% for all impurities. Copyright © 2011 Elsevier B.V. All rights reserved.

Investigation of the direct runoff generation mechanism for the analysis of the SCS-CN method applicability to a partial area experimental watershed

OpenAIRE

Soulis, K. X.; Valiantzas, J. D.; Dercas, N.; Londra, P. A.

2009-01-01

The Soil Conservation Service Curve Number (SCS-CN) method is widely used for predicting direct runoff volume for a given rainfall event. The applicability of the SCS-CN method and the direct runoff generation mechanism were thoroughly analysed in a Mediterranean experimental watershed in Greece. The region is characterized by a Mediterranean semi-arid climate. A detailed land cover and soil survey using remote sensing and GIS techniques, showed that the watershed is dominated by coarse soils...

Synthesis and Mechanical Characterization of Binary and Ternary Intermetallic Alloys Based on Fe-Ti-Al by Resonant Ultrasound Vibrational Methods.

Science.gov (United States)

Chanbi, Daoud; Ogam, Erick; Amara, Sif Eddine; Fellah, Z E A

2018-05-07

Precise but simple experimental and inverse methods allowing the recovery of mechanical material parameters are necessary for the exploration of materials with novel crystallographic structures and elastic properties, particularly for new materials and those existing only in theory. The alloys studied herein are of new atomic compositions. This paper reports an experimental study involving the synthesis and development of methods for the determination of the elastic properties of binary (Fe-Al, Fe-Ti and Ti-Al) and ternary (Fe-Ti-Al) intermetallic alloys with different concentrations of their individual constituents. The alloys studied were synthesized from high purity metals using an arc furnace with argon flow to ensure their uniformity and homogeneity. Precise but simple methods for the recovery of the elastic constants of the isotropic metals from resonant ultrasound vibration data were developed. These methods allowed the fine analysis of the relationships between the atomic concentration of a given constituent and the Young’s modulus or alloy density.

Characterization of gold kiwifruit pectin from fruit of different maturities and extraction methods.

Science.gov (United States)

Yuliarti, Oni; Matia-Merino, Lara; Goh, Kelvin K T; Mawson, John; Williams, Martin A K; Brennan, Charles

2015-01-01

Studies on gold kiwifruit pectins are limited. In this work, the characterization of pectin isolated from two different stages of maturity of gold kiwifruit, namely early harvested fruit (EHF) and main harvested fruit (MHF) isolated by three methods (acid, water, enzymatic) was carried out. Pectins isolated from MHF were higher in galacturonic acid content (52-59% w/w) and weight-average molecular weights (Mw, 1.7-3.8 × 10(6)g/mol) compared with EHF pectins (29-49% w/w and 0.2-1.7 × 10(6)g/mol respectively). Enzymatic treatment gave the highest yield but lowest in Mw, viscosity and mechanical spectra for both maturities. The pectin of both maturities was classified as high-methoxyl pectin with the degree of esterification ranged from 82% to 90%. Water-extracted MHF pectin molecules had the highest RMS radius (182.7 nm) and Mw (3.75 × 10(6)g/mol). The water extraction method appeared to retain the native state of pectin molecules compared with acid and enzymatic extraction methods based on the Mw and viscosity data. Copyright © 2014 Elsevier Ltd. All rights reserved.

On-Chip Method to Measure Mechanical Characteristics of a Single Cell by Using Moiré Fringe

Directory of Open Access Journals (Sweden)

Hirotaka Sugiura

2015-06-01

Full Text Available We propose a method to characterize the mechanical properties of cells using a robot-integrated microfluidic chip (robochip and microscopy. The microfluidic chip is designed to apply the specified deformations to a single detached cell using an on-chip actuator probe. The reaction force is simultaneously measured using an on-chip force sensor composed of a hollow folded beam and probe structure. In order to measure the cellular characteristics in further detail, a sub-pixel level of resolution of probe position is required. Therefore, we utilize the phase detection of moiré fringe. Using this method, the experimental resolution of the probe position reaches 42 nm. This is approximately ten times smaller than the optical wavelength, which is the limit of sharp imaging with a microscope. Calibration of the force sensor is also important in accurately measuring cellular reaction forces. We calibrated the spring constant from the frequency response, by the proposed sensing method of the probe position. As a representative of mechanical characteristics, we measured the elastic modulus of Madin-Darby Cannie Kidney (MDCK cells. In spite of the rigid spring constant, the resolution and sensitivity were twice that achieved in our previous study. Unique cellular characteristics can be elucidated by the improvements in sensing resolution and accuracy.

In Situ Mechanical Testing of Nanostructured Bijel Fibers.

Science.gov (United States)

Haase, Martin F; Sharifi-Mood, Nima; Lee, Daeyeon; Stebe, Kathleen J

2016-06-28

Bijels are a class of soft materials with potential for application in diverse areas including healthcare, food, energy, and reaction engineering due to their unique structural, mechanical, and transport properties. To realize their potential, means to fabricate, characterize, and manipulate bijel mechanics are needed. We recently developed a method based on solvent transfer-induced phase separation (STRIPS) that enables continuous fabrication of hierarchically structured bijel fibers from a broad array of constituent fluids and nanoparticles using a microfluidic platform. Here, we introduce an in situ technique to characterize bijel fiber mechanics at initial and final stages of the formation process within a microfluidics device. By manipulation of the hydrodynamic stresses applied to the fiber, the fiber is placed under tension until it breaks into segments. Analysis of the stress field allows fracture strength to be inferred; fracture strengths can be as high as several thousand Pa, depending on nanoparticle content. These findings broaden the potential for the use of STRIPS bijels in applications with different mechanical demands. Moreover, our in situ mechanical characterization method could potentially enable determination of properties of other soft fibrous materials made of hydrogels, capillary suspensions, colloidal gels, or high internal phase emulsions.

Assessing learning outcomes in middle-division classical mechanics: The Colorado Classical Mechanics and Math Methods Instrument

Directory of Open Access Journals (Sweden)

Marcos D. Caballero

2017-04-01

Full Text Available Reliable and validated assessments of introductory physics have been instrumental in driving curricular and pedagogical reforms that lead to improved student learning. As part of an effort to systematically improve our sophomore-level classical mechanics and math methods course (CM 1 at CU Boulder, we have developed a tool to assess student learning of CM 1 concepts in the upper division. The Colorado Classical Mechanics and Math Methods Instrument (CCMI builds on faculty consensus learning goals and systematic observations of student difficulties. The result is a 9-question open-ended post test that probes student learning in the first half of a two-semester classical mechanics and math methods sequence. In this paper, we describe the design and development of this instrument, its validation, and measurements made in classes at CU Boulder and elsewhere.

Microstructure characterization of ceramic nuclear fuel

International Nuclear Information System (INIS)

Boehmert, J.; Gaessner, W.

1984-08-01

A system of characterizing methods is described based on quantitative ceramographic methods. This system is applicable in quality assurance of UO 2 nuclear fuel in small-scale production and for determining microstructural parameters in scientific investigations. The system is based essentially on the measuring of microstructural parameters by the methods of linear analysis by the VEB Carl Zeiss Jena EPIQUANT mechanical optical microstructural analyzer. It is completed by measuring the pore size using automatic the television analyzer QTM. Before the quantitative microstructural characterization, in each case the morphology of the structure is estimated qualitatively. (author)

Mechanical characterization of Cu-Zn wire electrode base used in EDM and study of influence of the process of machining on its properties

Energy Technology Data Exchange (ETDEWEB)

Sedjal, H., E-mail: hasedjal@yahoo.fr; Amirat, B. [Département of Mechanical engineering, University of M.MAMMERI, Tizi Ouzou (Algeria); Aichour, M.; Marouf, T.; Chitroub, M. [Engineering and Material Sciences Laboratory, Department of Metallurgy, Polytechnic national school, Algiers (Algeria)

2015-03-30

This work is part of a Research National project (PNR) carried out by the group of research of the engineering and material sciences laboratory of the polytechnic national school at Algiers in collaboration with company BCR, which relates to “the characterization of the wire intended for the EDM of matrices metal. The goal of this work is to bring metallographic explanations on the wire electrode used by the machine ROBOFIL 290P, mechanically characterized this wire as of knowing of advantage about the process of its manufacturing (wiredrawing, .) The methods of studies used are it micro Vickers pyramid hardness, the tensile test, optical microscopy and scan electronic microscopy SEM.

Mineralogical and chemical characterization of various bentonite and smectite-rich clay materials Part A: Comparison and development of mineralogical characterization methods Part B: Mineralogical and chemical characterization of clay materials

International Nuclear Information System (INIS)

Kumpulainen, S.; Kiviranta, L.

2010-06-01

Mineralogy is an essential issue in understanding thermo-hydro-mechanical-chemical (THMC) behavior of bentonite materials. Mineralogy affects, among others, chemical composition of pore water, susceptibility for erosion, and transport of radionuclides. Consequently, mineralogy affects the designs of the buffer and backfill components. The objective of this work was to implement and develop mineralogical and chemical methods for characterization of reference clays considered for use as buffer and backfill materials in nuclear waste disposal. In this work, different methods were tested, compared, developed, and best available techniques selected. An additional aim was to characterize reference materials that are used in various nuclear waste disposal supporting studies, e.g., the SKB's alternative buffer material (ABM) experiment. Materials studied included three Wyoming-bentonites, two bentonites from Milos, four bentonites from Kutch district, and two Friedland clays. Minerals were identified using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and polarizing microscopy. Mineralogical composition was estimated using Rietveld-analysis. Chemical methods were used to support and validate mineralogical interpretation. Total chemical composition was determined from decomposed samples using spectrometry (ICP-AES) and combustion (Leco-S, Leco-C). Ferric and ferrous iron species were distinguished titrimetrically and the amount of soluble sulphate was determined using ion chromatography. In addition, cation exchange capacity and original exchangeable cations were determined. Chemical composition of fine (<2 μ m) fractions and poorly crystalline Fe-, Al- and Si-phases determined by selective extractions were used in structural calculations of smectite. XRD is a basic method for all mineralogical characterization, but it is insensitive for detecting trace minerals and variations in the structural chemical composition of clay minerals. Polarizing

Experimental Evolution of Diverse Strains as a Method for the Determination of Biochemical Mechanisms of Action for Novel Pyrrolizidinone Antibiotics.

Science.gov (United States)

Beabout, Kathryn; McCurry, Megan D; Mehta, Heer; Shah, Akshay A; Pulukuri, Kiran Kumar; Rigol, Stephan; Wang, Yanping; Nicolaou, K C; Shamoo, Yousif

2017-11-10

The continuing rise of multidrug resistant pathogens has made it clear that in the absence of new antibiotics we are moving toward a "postantibiotic" world, in which even routine infections will become increasingly untreatable. There is a clear need for the development of new antibiotics with truly novel mechanisms of action to combat multidrug resistant pathogens. Experimental evolution to resistance can be a useful tactic for the characterization of the biochemical mechanism of action for antibiotics of interest. Herein, we demonstrate that the use of a diverse panel of strains with well-annotated reference genomes improves the success of using experimental evolution to characterize the mechanism of action of a novel pyrrolizidinone antibiotic analog. Importantly, we used experimental evolution under conditions that favor strongly polymorphic populations to adapt a panel of three substantially different Gram-positive species (lab strain Bacillus subtilis and clinical strains methicillin-resistant Staphylococcus aureus MRSA131 and Enterococcus faecalis S613) to produce a sufficiently diverse set of evolutionary outcomes. Comparative whole genome sequencing (WGS) between the susceptible starting strain and the resistant strains was then used to identify the genetic changes within each species in response to the pyrrolizidinone. Taken together, the adaptive response across a range of organisms allowed us to develop a readily testable hypothesis for the mechanism of action of the CJ-16 264 analog. In conjunction with mitochondrial inhibition studies, we were able to elucidate that this novel pyrrolizidinone antibiotic is an electron transport chain (ETC) inhibitor. By studying evolution to resistance in a panel of different species of bacteria, we have developed an enhanced method for the characterization of new lead compounds for the discovery of new mechanisms of action.

Characterizing lentic freshwater fish assemblages using multiple sampling methods

Science.gov (United States)

Fischer, Jesse R.; Quist, Michael C.

2014-01-01

Characterizing fish assemblages in lentic ecosystems is difficult, and multiple sampling methods are almost always necessary to gain reliable estimates of indices such as species richness. However, most research focused on lentic fish sampling methodology has targeted recreationally important species, and little to no information is available regarding the influence of multiple methods and timing (i.e., temporal variation) on characterizing entire fish assemblages. Therefore, six lakes and impoundments (48–1,557 ha surface area) were sampled seasonally with seven gear types to evaluate the combined influence of sampling methods and timing on the number of species and individuals sampled. Probabilities of detection for species indicated strong selectivities and seasonal trends that provide guidance on optimal seasons to use gears when targeting multiple species. The evaluation of species richness and number of individuals sampled using multiple gear combinations demonstrated that appreciable benefits over relatively few gears (e.g., to four) used in optimal seasons were not present. Specifically, over 90 % of the species encountered with all gear types and season combinations (N = 19) from six lakes and reservoirs were sampled with nighttime boat electrofishing in the fall and benthic trawling, modified-fyke, and mini-fyke netting during the summer. Our results indicated that the characterization of lentic fish assemblages was highly influenced by the selection of sampling gears and seasons, but did not appear to be influenced by waterbody type (i.e., natural lake, impoundment). The standardization of data collected with multiple methods and seasons to account for bias is imperative to monitoring of lentic ecosystems and will provide researchers with increased reliability in their interpretations and decisions made using information on lentic fish assemblages.

Performance assessment of semiempirical molecular orbital methods in describing halogen bonding: quantum mechanical and quantum mechanical/molecular mechanical-molecular dynamics study.

Science.gov (United States)

Ibrahim, Mahmoud A A

2011-10-24

The performance of semiempirical molecular-orbital methods--MNDO, MNDO-d, AM1, RM1, PM3 and PM6--in describing halogen bonding was evaluated, and the results were compared with molecular mechanical (MM) and quantum mechanical (QM) data. Three types of performance were assessed: (1) geometrical optimizations and binding energy calculations for 27 halogen-containing molecules complexed with various Lewis bases (Two of the tested methods, AM1 and RM1, gave results that agree with the QM data.); (2) charge distribution calculations for halobenzene molecules, determined by calculating the solvation free energies of the molecules relative to benzene in explicit and implicit generalized Born (GB) solvents (None of the methods gave results that agree with the experimental data.); and (3) appropriateness of the semiempirical methods in the hybrid quantum-mechanical/molecular-mechanical (QM/MM) scheme, investigated by studying the molecular inhibition of CK2 protein by eight halobenzimidazole and -benzotriazole derivatives using hybrid QM/MM molecular-dynamics (MD) simulations with the inhibitor described at the QM level by the AM1 method and the rest of the system described at the MM level. The pure MM approach with inclusion of an extra point of positive charge on the halogen atom approach gave better results than the hybrid QM/MM approach involving the AM1 method. Also, in comparison with the pure MM-GBSA (generalized Born surface area) binding energies and experimental data, the calculated QM/MM-GBSA binding energies of the inhibitors were improved by replacing the G(GB,QM/MM) solvation term with the corresponding G(GB,MM) term.

Characterization of an electroactive polymer simultaneously driven by an electrical field and a mechanical excitation: An easy means of measuring the dielectric constant, the Young modulus and the electrostrictive coefficients

International Nuclear Information System (INIS)

Guyomar, Daniel; Cottinet, Pierre-Jean; Lebrun, Laurent; Sebald, Gael

2011-01-01

An easy method for measuring the dielectric constant, the Young modulus and the electrostrictive coefficients of a polymer film is proposed herein. The approach was based on the determination of the current flowing through the sample when simultaneously driven by an electrical field and a mechanical excitation. The experimental data were in good agreement with published results. In addition, the method rendered it possible to characterize the film sample under real conditions. - Highlights: → In this study we model a multiphysic coupling in electroactive polymer (EAP). → A new method was developed to determine the different coefficient of the material. → The results demonstrated the potential of this method for the characterization of EAP.

A radiometric method for the characterization of particulate processes in colloidal suspensions. II

International Nuclear Information System (INIS)

Subotic, B.

1979-01-01

A radiometric method for the characterization of particulate processes is verified using stable hydrosols of silver iodide. Silver iodide hydrosols satisfy the conditions required for the applications of the proposed method. Comparison shows that the values for the change of particle size measured in silver iodide hydrosols by the proposed method are in excellent agreement with the values obtained by other methods on the same systems (electron microscopy, sedimentation analysis, light scattering). This shows that the proposed method is suitable for the characterization of particulate processes in colloidal suspensions. (Auth.

Mechanical stability of surface architecture--consequences for superhydrophobicity.

Science.gov (United States)

Dyett, Brendan P; Wu, Alex H; Lamb, Robert N

2014-11-12

Wet chemistry methods such as sol-gel provide a facile means of preparing coatings with controlled surface chemistry and architecture. The manipulation of colloidal "building blocks," film constituents, and reaction conditions makes it a promising method for simple, scalable, and routine production of superhydrophobic coatings. Despite all of this, the practical application of superhydrophobic coatings remains limited by low mechanical durability. The translation of chemistry to mechanical strength within superhydrophobic films is severely hindered by the requisite physical structure. More specifically, porosity and the surface architecture of roughness in sol-gel-derived films contribute significantly to poor mechanical properties. These physical effects emphasize that collective structure and chemistry-based strategies are required. This challenge is not unique to superhydrophobics, and there are many principles that can be drawn upon to greatly improve performance. The delicate interplay between chemistry and physical structure has been highlighted through theory and characterization of porous and rough interfaces within and outside the framework of superhydrophobics. Insights can further be drawn from biology. Nature's capacity for self-repair remains extremely challenging to mimic in materials. However, nature does demonstrate strategies for structuring nano- and microbuilding blocks to achieve generally mutually exclusive properties. Difficulties with characterization and example mechanical characterization methods have also been emphasized.

Mechanical characterization and single asperity scratch behaviour of dry zinc and manganese phosphate coatings

NARCIS (Netherlands)

Ernens, D.; de Rooij, M. B.; Pasaribu, H. R.; van Riet, E.J.; van Haaften, W.M.; Schipper, D. J.

The goal of this study is to characterise the mechanical properties of zinc and manganese phosphate coatings before and after running in. The characterization is done with nano-indentation to determine the individual crystal hardness and single asperity scratch tests to investigate the deformation

Method to characterize dielectric properties of powdery substances

Science.gov (United States)

Tuhkala, M.; Juuti, J.; Jantunen, H.

2013-07-01

An open ended coaxial cavity method for dielectric characterization of powdery substance operating at 4.5 GHz in TEM mode is presented. Classical mixing rules and electromagnetic modeling were utilized with measured effective permittivities and Q factors to determine the relative permittivity and dielectric loss tangent of different powders with ɛr up to 30. The modeling enabled determination of the correction factor for the simplified equation for the relative permittivity of an open ended coaxial resonator and mixing rules having the best correlation with experiments. SiO2, Al2O3, LTCC CT 2000, ZrO2, and La2O3 powders were used in the experiments. Based on the measured properties and Bruggeman symmetric and Looyenga mixing rules, the determined dielectric characteristics of the powders exhibited good correlation with values in the literature. The presented characterization method enabled the determination of dielectric properties of powdery substances within the presented range, and therefore could be applied to various research fields and applications where dielectric properties of powders need to be known and controlled.

New Technologies Provide Quantum Changes in the Scale, Speed, and Success of SELEX Methods and Aptamer Characterization

Directory of Open Access Journals (Sweden)

Abdullah Ozer

2014-01-01

Full Text Available Single-stranded oligonucleotide aptamers have attracted great attention in the past decade because of their diagnostic and therapeutic potential. These versatile, high affinity and specificity reagents are selected by an iterative in vitro process called SELEX, Systematic Evolution of Ligands by Exponential Enrichment. Numerous SELEX methods have been developed for aptamer selections; some that are simple and straightforward, and some that are specialized and complicated. The method of SELEX is crucial for selection of an aptamer with desired properties; however, success also depends on the starting aptamer library, the target molecule, aptamer enrichment monitoring assays, and finally, the analysis and characterization of selected aptamers. Here, we summarize key recent developments in aptamer selection methods, as well as other aspects of aptamer selection that have significant impact on the outcome. We discuss potential pitfalls and limitations in the selection process with an eye to aid researchers in the choice of a proper SELEX strategy, and we highlight areas where further developments and improvements are desired. We believe carefully designed multiplexed selection methods, when complemented with high-throughput downstream analysis and characterization assays, will yield numerous high-affinity aptamers to protein and small molecule targets, and thereby generate a vast array of reagents for probing basic biological mechanisms and implementing new diagnostic and therapeutic applications in the near future.

Development of characterization methods applied to radioactive wastes and waste packages

International Nuclear Information System (INIS)

Guy, C.; Bienvenu, Ph.; Comte, J.; Excoffier, E.; Dodi, A.; Gal, O.; Gmar, M.; Jeanneau, F.; Poumarede, B.; Tola, F.; Moulin, V.; Jallu, F.; Lyoussi, A.; Ma, J.L.; Oriol, L.; Passard, Ch.; Perot, B.; Pettier, J.L.; Raoux, A.C.; Thierry, R.

2004-01-01

This document is a compilation of R and D studies carried out in the framework of the axis 3 of the December 1991 law about the conditioning and storage of high-level and long lived radioactive wastes and waste packages, and relative to the methods of characterization of these wastes. This R and D work has permitted to implement and qualify new methods (characterization of long-lived radioelements, high energy imaging..) and also to improve the existing methods by lowering detection limits and reducing uncertainties of measured data. This document is the result of the scientific production of several CEA laboratories that use complementary techniques: destructive methods and radiochemical analyses, photo-fission and active photonic interrogation, high energy imaging systems, neutron interrogation, gamma spectroscopy and active and passive imaging techniques. (J.S.)

CHARACTERIZATION AND PROCESSING OF SCALES FROM THE MECHANICAL DESCALING OF CARBON STEELS FOR RECYCLING AS COATING PIGMENTS

Directory of Open Access Journals (Sweden)

Anderson de Oliveira Fraga

2014-10-01

Full Text Available The large volume of solid wastes generated as scales in Steel Mills accounts to circa 1% to 2% of the total steel production and has led to studies aiming the recycling of scales, usually resulting in products of low added value. In this study, scales from the mechanical descaling of SAE 1045 steel were characterized by SEM and by quantitative X-Ray diffraction (Rietveld method, as well as by differential thermal analysis, aiming to develop its pretreatment for the further use as lamellar pigments in anticorrosive coatings of high added value. Aspect ratios between 1:50 and 1:100 were obtained by the processing of scales, which allows the replacement of other micaceous iron oxides.

Mechanical properties of the rust layer induced by impressed current method in reinforced mortar

International Nuclear Information System (INIS)

Care, S.; Nguyen, Q.T.; L'Hostis, V.; Berthaud, Y.

2008-01-01

This paper describes the mechanical effects of rust layer formed in reinforced mortar through accelerated tests of corrosion. The morphological and physico-chemical properties (composition, structures) of the corrosion system were characterized at different stages by using optical microscope and scanning electron microscope coupled with energy dispersive spectroscopy. The corrosion pattern was mainly characterized by a rust layer confined at the interface between the steel and the mortar. Expansion coefficient of rust products was determined from the rust thickness and the Faraday's law. Furthermore, in order to understand the mechanical effects of corrosion on the damage of mortar, displacement field measurements were obtained by using digital image correlation. An analytical model (hollow cylinder subjected to inner and outer pressures) was used with a set of experimental data to deduce the time of cracking and the order of magnitude of the mechanical properties of the rust layer

A computational modeling approach for the characterization of mechanical properties of 3D alginate tissue scaffolds.

Science.gov (United States)

Nair, K; Yan, K C; Sun, W

2008-01-01

Scaffold guided tissue engineering is an innovative approach wherein cells are seeded onto biocompatible and biodegradable materials to form 3-dimensional (3D) constructs that, when implanted in the body facilitate the regeneration of tissue. Tissue scaffolds act as artificial extracellular matrix providing the environment conducive for tissue growth. Characterization of scaffold properties is necessary to understand better the underlying processes involved in controlling cell behavior and formation of functional tissue. We report a computational modeling approach to characterize mechanical properties of 3D gellike biomaterial, specifically, 3D alginate scaffold encapsulated with cells. Alginate inherent nonlinearity and variations arising from minute changes in its concentration and viscosity make experimental evaluation of its mechanical properties a challenging and time consuming task. We developed an in silico model to determine the stress-strain relationship of alginate based scaffolds from experimental data. In particular, we compared the Ogden hyperelastic model to other hyperelastic material models and determined that this model was the most suitable to characterize the nonlinear behavior of alginate. We further propose a mathematical model that represents the alginate material constants in Ogden model as a function of concentrations and viscosity. This study demonstrates the model capability to predict mechanical properties of 3D alginate scaffolds.

Feed mechanism and method for feeding minute items

Science.gov (United States)

Stringer, Timothy Kent [Bucyrus, KS; Yerganian, Simon Scott [Lee's Summit, MO

2009-10-20

A feeding mechanism and method for feeding minute items, such as capacitors, resistors, or solder preforms. The mechanism is adapted to receive a plurality of the randomly-positioned and randomly-oriented extremely small or minute items, and to isolate, orient, and position one or more of the items in a specific repeatable pickup location wherefrom they may be removed for use by, for example, a computer-controlled automated assembly machine. The mechanism comprises a sliding shelf adapted to receive and support the items; a wiper arm adapted to achieve a single even layer of the items; and a pushing arm adapted to push the items into the pickup location. The mechanism can be adapted for providing the items with a more exact orientation, and can also be adapted for use in a liquid environment.

Mechanical property characterization of polymeric composites reinforced by continuous microfibers

Science.gov (United States)

Zubayar, Ali

Innumerable experimental works have been conducted to study the effect of polymerization on the potential properties of the composites. Experimental techniques are employed to understand the effects of various fibers, their volume fractions and matrix properties in polymer composites. However, these experiments require fabrication of various composites which are time consuming and cost prohibitive. Advances in computational micromechanics allow us to study the various polymer based composites by using finite element simulations. The mechanical properties of continuous fiber composite strands are directional. In traditional continuous fiber laminated composites, all fibers lie in the same plane. This provides very desirable increases in the in-plane mechanical properties, but little in the transverse mechanical properties. The effect of different fiber/matrix combinations with various orientations is also available. Overall mechanical properties of different micro continuous fiber reinforced composites with orthogonal geometry are still unavailable in the contemporary research field. In this research, the mechanical properties of advanced polymeric composite reinforced by continuous micro fiber will be characterized based on analytical investigation and FE computational modeling. Initially, we have chosen IM7/PEEK, Carbon Fiber/Nylon 6, and Carbon Fiber/Epoxy as three different case study materials for analysis. To obtain the equivalent properties of the micro-hetero structures, a concept of micro-scale representative volume elements (RVEs) is introduced. Five types of micro scale RVEs (3 square and 2 hexagonal) containing a continuous micro fiber in the polymer matrix were designed. Uniaxial tensile, lateral expansion and transverse shear tests on each RVE were designed and conducted by the finite element computer modeling software ANSYS. The formulae based on elasticity theory were derived for extracting the equivalent mechanical properties (Young's moduli, shear

Waste characterization methods at belgoprocess and the importance of NDA

International Nuclear Information System (INIS)

Botte, J.; Luycx, P.

2003-01-01

Waste characterization in the end cycle becomes more and more important. Several methods are available for a radiological characterization: from copying the waste producers declaration over a calculation based on known characteristics or measured values to combinations of several techniques. The decision on what technique(s) to be used will be based on several criteria. One also has to evaluate at what stage of the waste treatment process the characterization has to be performed. Recently belgoprocess has performed large efforts and investments to assure a good waste characterization. These are concentrated in studies on historical and recent waste, resulting in isotopic vectors and the purchase of several NDA devices in order to cover the whole scala of waste the company treats. The measuring results always need to be integrated with isotopic vectors. (orig.)

Characterization of polymer surface structure and surface mechanical behaviour by sum frequency generation surface vibrational spectroscopy and atomic force microscopy

International Nuclear Information System (INIS)

Opdahl, Aric; Koffas, Telly S; Amitay-Sadovsky, Ella; Kim, Joonyeong; Somorjai, Gabor A

2004-01-01

Sum frequency generation (SFG) vibrational spectroscopy and atomic force microscopy (AFM) have been used to study polymer surface structure and surface mechanical behaviour, specifically to study the relationships between the surface properties of polymers and their bulk compositions and the environment to which the polymer is exposed. The combination of SFG surface vibrational spectroscopy and AFM has been used to study surface segregation behaviour of polyolefin blends at the polymer/air and polymer/solid interfaces. SFG surface vibrational spectroscopy and AFM experiments have also been performed to characterize the properties of polymer/liquid and polymer/polymer interfaces, focusing on hydrogel materials. A method was developed to study the surface properties of hydrogel contact lens materials at various hydration conditions. Finally, the effect of mechanical stretching on the surface composition and surface mechanical behaviour of phase-separated polyurethanes, used in biomedical implant devices, has been studied by both SFG surface vibrational spectroscopy and AFM. (topical review)

Comparison of Moringa Oleifera seeds oil characterization produced chemically and mechanically

Science.gov (United States)

Eman, N. A.; Muhamad, K. N. S.

2016-06-01

It is established that virtually every part of the Moringa oleifera tree (leaves, stem, bark, root, flowers, seeds, and seeds oil) are beneficial in some way with great benefits to human being. The tree is rich in proteins, vitamins, minerals. All Moringa oleifera food products have a very high nutritional value. They are eaten directly as food, as supplements, and as seasonings as well as fodder for animals. The purpose of this research is to investigate the effect of seeds particle size on oil extraction using chemical method (solvent extraction). Also, to compare Moringa oleifera seeds oil properties which are produced chemically (solvent extraction) and mechanically (mechanical press). The Moringa oleifera seeds were grinded, sieved, and the oil was extracted using soxhlet extraction technique with n-Hexane using three different size of sample (2mm, 1mm, and 500μm). The average oil yield was 36.1%, 40.80%, and 41.5% for 2mm, 1mm, and 500μm particle size, respectively. The properties of Moringa oleifera seeds oil were: density of 873 kg/m3, and 880 kg/m3, kinematic viscosity of 42.2mm2/s and 9.12mm2/s for the mechanical and chemical method, respectively. pH, cloud point and pour point were same for oil produced with both methods which is 6, 18°C and 12°C, respectively. For the fatty acids, the oleic acid is present with high percentage of 75.39%, and 73.60% from chemical and mechanical method, respectively. Other fatty acids are present as well in both samples which are (Gadoleic acid, Behenic acid, Palmitic acid) which are with lower percentage of 2.54%, 5.83%, and 5.73%, respectively in chemical method oil, while they present as 2.40%, 6.73%, and 6.04%, respectively in mechanical method oil. In conclusion, the results showed that both methods can produce oil with high quality. Moringa oleifera seeds oil appear to be an acceptable good source for oil rich in oleic acid which is equal to olive oil quality, that can be consumed in Malaysia where the olive oil

A method for automated processing of measurement information during mechanical drilling

Energy Technology Data Exchange (ETDEWEB)

Samonenko, V.I.; Belinkov, V.G.; Romanova, L.A.

1984-01-01

An algorithm is cited for a developed method for automated processing of measurement information during mechanical drilling. Its use in conditions of operation of an automated control system (ASU) from drilling will make it possible to precisely identify a change in the lithology, the physical and mechanical and the abrasive properties, in the stratum (pore) pressure in the rock being drilled out during mechanical drilling, which along with other methods for testing the drilling process will increase the reliability of the decisions made.

Quantum mechanical fragment methods based on partitioning atoms or partitioning coordinates.

Science.gov (United States)

Wang, Bo; Yang, Ke R; Xu, Xuefei; Isegawa, Miho; Leverentz, Hannah R; Truhlar, Donald G

2014-09-16

Conspectus The development of more efficient and more accurate ways to represent reactive potential energy surfaces is a requirement for extending the simulation of large systems to more complex systems, longer-time dynamical processes, and more complete statistical mechanical sampling. One way to treat large systems is by direct dynamics fragment methods. Another way is by fitting system-specific analytic potential energy functions with methods adapted to large systems. Here we consider both approaches. First we consider three fragment methods that allow a given monomer to appear in more than one fragment. The first two approaches are the electrostatically embedded many-body (EE-MB) expansion and the electrostatically embedded many-body expansion of the correlation energy (EE-MB-CE), which we have shown to yield quite accurate results even when one restricts the calculations to include only electrostatically embedded dimers. The third fragment method is the electrostatically embedded molecular tailoring approach (EE-MTA), which is more flexible than EE-MB and EE-MB-CE. We show that electrostatic embedding greatly improves the accuracy of these approaches compared with the original unembedded approaches. Quantum mechanical fragment methods share with combined quantum mechanical/molecular mechanical (QM/MM) methods the need to treat a quantum mechanical fragment in the presence of the rest of the system, which is especially challenging for those parts of the rest of the system that are close to the boundary of the quantum mechanical fragment. This is a delicate matter even for fragments that are not covalently bonded to the rest of the system, but it becomes even more difficult when the boundary of the quantum mechanical fragment cuts a bond. We have developed a suite of methods for more realistically treating interactions across such boundaries. These methods include redistributing and balancing the external partial atomic charges and the use of tuned fluorine

X-ray methods for the chemical characterization of atmospheric aerosols

International Nuclear Information System (INIS)

Jaklevic, J.M.; Thompson, A.C.

1981-05-01

The development and use of several x-ray methods for the chemical characterization of atmospherical aerosol particulate samples are described. These methods are based on the emission, absorption, and scattering of x-ray photons with emphasis on the optimization for the non-destructive analysis of dilute specimens. Techniques discussed include photon induced energy dispersive x-ray fluorescence, extended x-ray absorption fine structure spectroscopy using synchrotron radiation and high-rate x-ray powder diffractometry using a position-sensitive gas proportional counter. These x-ray analysis methods were applied to the measurement of the chemical compositions of size-segregated aerosol particulate samples obtained with dichotomous samplers. The advantages of the various methods for use in such measurements are described and results are presented. In many cases, the complementary nature of the analytical information obtained from the various measurements is an important factor in the characterization of the sample. For example, the multiple elemental analyses obtained from x-ray fluorescence can be used as a cross check on the major compounds observed by powder diffraction

Mechanical properties of MeV ion-irradiated SiC/SiC composites characterized by indentation technique

International Nuclear Information System (INIS)

Park, J.Y.; Park, K.H.; Kim, W.; Kishimoto, H.; Kohyama, A.

2007-01-01

Full text of publication follows: SiC/SiC composites have been considered as a structural material for advanced fusion concepts. In the core of fusion reactor, those SiC/SiC composites are experienced the complex attacks such as strong neutron, high temperature and transmuted gases. One of the vital data for designing the SiC/SiC composites to the fusion reactor is mechanical properties under the severe neutron irradiation. In this work, various SiC/SiC composites were prepared by the different fabrication processes like CVI (chemical vapor infiltration), WA-CVI (SiC whisker assisted CVI) and hot-pressed method. The expected neutron irradiation was simulated by a silicon self-ion irradiation at a DuET facility; Dual-beam for Energy Technologies, Kyoto University. The irradiation temperature were 600 deg. C and 1200 deg. C, and the irradiation does were 5 dpa and 20 dpa, respectively. The 5.1 MeV Si ions were irradiated to the intrinsic CVI-SiC, SiC whisker reinforced SiC and SiC composites produced by hot-press method. The mechanical properties like hardness, elastic modulus and fracture toughness were characterized by an indentation technique. The ion irradiation caused the increase of the hardness and fracture toughness, which was dependent on the irradiation temperature. SiC whisker reinforcement in the SiC matrix accelerated the increase of the fracture toughness by the ion irradiation. For SiC/SiC composites after the ion irradiation, this work will provide the additional data for the mechanical properties as well as the effect of SiC whisker reinforcement. (authors)

Manufacture and characterization of austenitic steel welded joints

International Nuclear Information System (INIS)

Simoni, O.; Boerman, D.J.; Krischer, W.

1990-01-01

This paper describes the results of the first phase of the project, i.e. manufacturing and characterization of welded austenitic steel and the test matrix adopted to test the mechanical resistance of the welding. Five different welding methods have been tested and characterized in comparison to the parent material. The reference material was an AISI 316 L type steel close to the French Superphenix composition. The results of the mechanical testing and the relative comparison of the five welding methods are described in separate papers of the same session. As a general conclusion, the vacuum electron-beam welding proved to have better properties than the other weld methods and to attain in most cases the properties of the parent material. (author)

Characterization of mechanical properties of pericardium tissue using planar biaxial tension and flexural deformation.

Science.gov (United States)

Murdock, Kyle; Martin, Caitlin; Sun, Wei

2018-01-01

Flexure is an important mode of deformation for native and bioprosthetic heart valves. However, mechanical characterization of bioprosthetic leaflet materials has been done primarily through planar tensile testing. In this study, an integrated experimental and computational cantilever beam bending test was performed to characterize the flexural properties of glutaraldehyde-treated bovine and porcine pericardium of different thicknesses. A strain-invariant based structural constitutive model was used to model the pericardial mechanical behavior quantified through the bending tests of this study and the planar biaxial tests previously performed. The model parameters were optimized through an inverse finite element (FE) procedure in order to describe both sets of experimental data. The optimized material properties were implemented in FE simulations of transcatheter aortic valve (TAV) deformation. It was observed that porcine pericardium TAV leaflets experienced significantly more flexure than bovine when subjected to opening pressurization, and that the flexure may be overestimated using a constitutive model derived from purely planar tensile experimental data. Thus, modeling of a combination of flexural and biaxial tensile testing data may be necessary to more accurately describe the mechanical properties of pericardium, and to computationally investigate bioprosthetic leaflet function and design. Copyright © 2017 Elsevier Ltd. All rights reserved.

Methodic of practical study teaching on subject 'Characteristic mechanical oscillations'

International Nuclear Information System (INIS)

Tenchurina, A.R.

2006-01-01

In this article the methodic of the undertaking the practical lesson for subject 'the own mechanical vibrations' is considered and offered the algorithm of the problem decision the finding of the vibration period for the different mechanical systems. (author)

Reduction of very large reaction mechanisms using methods based on simulation error minimization

Energy Technology Data Exchange (ETDEWEB)

Nagy, Tibor; Turanyi, Tamas [Institute of Chemistry, Eoetvoes University (ELTE), P.O. Box 32, H-1518 Budapest (Hungary)

2009-02-15

A new species reduction method called the Simulation Error Minimization Connectivity Method (SEM-CM) was developed. According to the SEM-CM algorithm, a mechanism building procedure is started from the important species. Strongly connected sets of species, identified on the basis of the normalized Jacobian, are added and several consistent mechanisms are produced. The combustion model is simulated with each of these mechanisms and the mechanism causing the smallest error (i.e. deviation from the model that uses the full mechanism), considering the important species only, is selected. Then, in several steps other strongly connected sets of species are added, the size of the mechanism is gradually increased and the procedure is terminated when the error becomes smaller than the required threshold. A new method for the elimination of redundant reactions is also presented, which is called the Principal Component Analysis of Matrix F with Simulation Error Minimization (SEM-PCAF). According to this method, several reduced mechanisms are produced by using various PCAF thresholds. The reduced mechanism having the least CPU time requirement among the ones having almost the smallest error is selected. Application of SEM-CM and SEM-PCAF together provides a very efficient way to eliminate redundant species and reactions from large mechanisms. The suggested approach was tested on a mechanism containing 6874 irreversible reactions of 345 species that describes methane partial oxidation to high conversion. The aim is to accurately reproduce the concentration-time profiles of 12 major species with less than 5% error at the conditions of an industrial application. The reduced mechanism consists of 246 reactions of 47 species and its simulation is 116 times faster than using the full mechanism. The SEM-CM was found to be more effective than the classic Connectivity Method, and also than the DRG, two-stage DRG, DRGASA, basic DRGEP and extended DRGEP methods. (author)

Mechanical characterization and modelling of the heavy tungsten allow IT180

CERN Document Server

Scapin, M

2015-01-01

In this work, the mechanical characterization and the consequent material modeling of the tungsten alloy INERMET® IT180 were performed. The material is actually used in the collimation system of the Large Hadron Collider at CERN and several studies are currently under development in order to be able to numerically predict the material damage in case of energy beamimpact, but to do this, a confident strength model has to be obtained. This is the basis of this work, in which a test campaign in compression and tension at different strain-rates and tempe...

Method of dimensionality reduction in contact mechanics and friction

CERN Document Server

Popov, Valentin L

2015-01-01

This book describes for the first time a simulation method for the fast calculation of contact properties and friction between rough surfaces in a complete form. In contrast to existing simulation methods, the method of dimensionality reduction (MDR) is based on the exact mapping of various types of three-dimensional contact problems onto contacts of one-dimensional foundations. Within the confines of MDR, not only are three dimensional systems reduced to one-dimensional, but also the resulting degrees of freedom are independent from another. Therefore, MDR results in an enormous reduction of the development time for the numerical implementation of contact problems as well as the direct computation time and can ultimately assume a similar role in tribology as FEM has in structure mechanics or CFD methods, in hydrodynamics. Furthermore, it substantially simplifies analytical calculation and presents a sort of “pocket book edition” of the entirety contact mechanics. Measurements of the rheology of bodies in...

Characterization for Ceramic-coated magnets using E-beam and thermal annealing methods

International Nuclear Information System (INIS)

Kim, Hyug Jong; Kim, Hee Gyu; Kang, In Gu; Kim, Min Wan; Yang, Ki Ho; Lee, Byung Cheol; Choi, Byung Ho

2009-01-01

Hard magnet was usually used by coating SiO 2 ceramic thick films followed by the thermal annealing process. In this work, the alternative annealing process for NdFeB magnets using e-beam sources(1∼2 MeV, 50∼400 kGy) was investigated. NdFeB magnets was coated with ceramic thick films using the spray method. The optimal annealing parameter for e-beam source reveals to be 1 MeV and 300 kGy. The sample prepared at 1 MeV and 300 kGy was characterized by the analysis of the surface morphology, film hardness, adhesion and chemical stability. The mechanical property of thick film, especially film hardness, is better than that of thermal annealed samples at 180 .deg. C. As a result, e-beam annealing process will be one of candidate and attractive heat treatment process. In future, manufacturing process will be carried out in cooperation with the magnet company

Synthesis and growth mechanism of sponge-like nickel using a hydrothermal method

Science.gov (United States)

Shao, Bin; Yin, Xueguo; Hua, Weidong; Ma, Yilong; Sun, Jianchun; Li, Chunhong; Chen, Dengming; Guo, Donglin; Li, Kejian

2018-05-01

Sponge-like nickel composed of micro-chains with a diameter of 1-5 μm was selectively synthesized by the hydrothermal method, using sodium hydroxide (NaOH) as the alkaline reagent, aqueous hydrazine as reducing agent and citric acid as a coordination agent. The time-dependent samples prepared at different NaOH concentrations were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrometer (FTIR). The results showed that the agglomerates of nickel citrate hydrazine complex nanoplates were first precipitated and then reduced to prickly nickel micro-chains at a lower NaOH concentration, which played a role in the further formation of sponge-like nickel. Also, the probable growth mechanism of the sponge-like nickel was proposed. The magnetic properties of sponge-like nickel were studied using a vibrating sample magnetometer. The sponge-like nickel exhibited a ferromagnetic behavior with a saturation magnetization value of 43.8 emu g-1 and a coercivity value of 120.7 Oe.

Mechanical characterization and assessment of the CMS conductor

CERN Document Server

Sequeira-Lopes-Tavares, S; Desirelli, Alberto; Sgobba, Stefano; Horváth, I L

2000-01-01

The Compact Muon Solenoid (CMS) is one of the experiments which are being designed in the framework of the Large Hadron Collider (LHC) project at CERN. The design field of the CMS magnet is 4 T, the magnetic length is 12.5m and the free aperture is 6 m in diameter. This is achieved with a 4 layer and 5 module superconducting Al stabilized coil, resulting into 20 lengths of conductor of 2.5 km each, energized at a nominal current of 20 kA at 4.5 K. One of the unique features of this thin solenoid is an Al-stabilized conductor reinforced by an Al-alloy. An extensive characterization of mechanical properties at room temperature and 4.2 K has been carried out in order to define the most appropriate alloy and temper for the reinforcement. The effect of the coil curing cycle on the alloy properties has been taken into account. This paper summarizes the main results of these tests. (7 refs).

Electron beam crosslinked gels-Preparation, characterization and their effect on the mechanical, dynamic mechanical and rheological properties of rubbers

Energy Technology Data Exchange (ETDEWEB)

Mitra, Suman; Chattopadhyay, Santanu [Rubber Technology Centre, Indian Institute of Technology, Kharagpur 721302 (India); Sabharwal, Sunil [Radiation Technology Development Section, Bhabha Atomic Research Center, Trombay, Mumbai 400085 (India); Bhowmick, Anil K., E-mail: anilkb@rtc.iitkgp.ernet.i [Rubber Technology Centre, Indian Institute of Technology, Kharagpur 721302 (India)

2010-03-15

Electron beam (EB) crosslinked natural rubber (NR) gels were prepared by curing NR latex with EB irradiation over a range of doses from 2.5 to 20 kGy using butyl acrylate as sensitizer. The NR gels were systematically characterized by solvent swelling, dynamic light scattering, mechanical and dynamic mechanical properties. These gels were introduced in virgin NR and styrene butadiene rubber (SBR) matrices at 2, 4, 8 and 16 phr concentration. Addition of the gels improved the mechanical and dynamic mechanical properties of NR and SBR considerably. For example, 16 phr of 20 kGy EB-irradiated gel-filled NR showed a tensile strength of 3.53 MPa compared to 1.85 MPa of virgin NR. Introduction of gels in NR shifted the glass transition temperature to a higher temperature. A similar effect was observed in the case of NR gel-filled SBR systems. Morphology of the gel-filled systems was studied with atomic force microscopy. The NR gels also improved the processability of the virgin rubbers greatly. Both the shear viscosity and the die swell values of EB-irradiated gel-filled NR and SBR were lower than their virgin counterparts as investigated by capillary rheometer.

Electron beam crosslinked gels-Preparation, characterization and their effect on the mechanical, dynamic mechanical and rheological properties of rubbers

International Nuclear Information System (INIS)

Mitra, Suman; Chattopadhyay, Santanu; Sabharwal, Sunil; Bhowmick, Anil K.

2010-01-01

Electron beam (EB) crosslinked natural rubber (NR) gels were prepared by curing NR latex with EB irradiation over a range of doses from 2.5 to 20 kGy using butyl acrylate as sensitizer. The NR gels were systematically characterized by solvent swelling, dynamic light scattering, mechanical and dynamic mechanical properties. These gels were introduced in virgin NR and styrene butadiene rubber (SBR) matrices at 2, 4, 8 and 16 phr concentration. Addition of the gels improved the mechanical and dynamic mechanical properties of NR and SBR considerably. For example, 16 phr of 20 kGy EB-irradiated gel-filled NR showed a tensile strength of 3.53 MPa compared to 1.85 MPa of virgin NR. Introduction of gels in NR shifted the glass transition temperature to a higher temperature. A similar effect was observed in the case of NR gel-filled SBR systems. Morphology of the gel-filled systems was studied with atomic force microscopy. The NR gels also improved the processability of the virgin rubbers greatly. Both the shear viscosity and the die swell values of EB-irradiated gel-filled NR and SBR were lower than their virgin counterparts as investigated by capillary rheometer.

Wsbnd Cu functionally graded material: Low temperature fabrication and mechanical characterization

Science.gov (United States)

Yusefi, Ali; Parvin, Nader; Mohammadi, Hossein

2018-04-01

In this study, we fabricated and characterized a Wsbnd Cu functionally graded material (FGM) with 11 layers, including a pure copper layer. Samples were prepared by mixing a mechanically alloyed Nisbnd Mnsbnd Cu powder with W and Cu powders, stacking the powders, pressing the stacked layers, and finally sintering at 1000 °C. The utilization of a Nisbnd Mnsbnd Cu system may reduce the cost but without losing the good sintering behavior and physical and mechanical properties. The composition of the material was analyzed based on scanning electron microscopy images and by energy dispersive X-ray spectroscopy mapping, which indicated that in the presence of Ni and Mn, the Cu atoms could diffuse into the W particles. All of the layers had a very high relative density, thereby indicating their densification and excellent sintering behavior. We also found that the porosity values in the Cu phase remained unchanged at approximately 2.39% across the FGM. Mechanical measurements showed that the hardness (72%), modulus of elasticity (61%), and ultimate tensile strength (58%) increased with the W content across the Wsbnd Cu FGM, whereas the fracture toughness (KIC) varied in the opposite manner (minimum of 4.52 MPa/m0.5).

Investigation of noninvasive healing of damaged piping system using electro-magneto-mechanical methods

KAUST Repository

Mukherjee, Debanjan; Zaky, Zeyad; Zohdi, Tarek Ismail; Salama, Amgad; Sun, Shuyu

2014-01-01

role for guiding the particles to the solid-fluid interface/wall: mechanical shear due to the fluid flow, and an electrical or magnetic force. In this work we develop and study a relationship that characterizes contributions of both, and ascertain how

2012 Annual Conference on Experimental and Applied Mechanics

CERN Document Server

Crone, Wendy; Jin, Helena; Sciammarella, Cesar; Furlong, Cosme; Furlong, Cosme; Chalivendra, Vijay; Song, Bo; Casem, Daniel; Antoun, Bonnie; Qi, H; Hall, Richard; Tandon, GP; Lu, Hongbing; Lu, Charles; Yoshida, Sanichiro; Shaw, Gordon; Prorok, Barton; Barthelat, François; Korach, Chad; Grande-Allen, K; Lipke, Elizabeth; Lykofatitits, George; Zavattieri, Pablo; Starman, LaVern; Patterson, Eann; Backman, David; Cloud, Gary; Vol.1 Dynamic Behavior of Materials; Vol.2 Challenges in Mechanics of Time-Dependent Materials and Processes in Conventional and Multifunctional Materials; Vol.3 Imaging Methods for Novel Materials and Challenging Applications; Vol.4 Experimental and Applied Mechanics; Vol.5 Mechanics of Biological Systems and Materials; Vol.6 MEMS and Nanotechnology; Vol.7 Composite Materials and Joining Technologies for Composites

2013-01-01

Experimental and Applied Mechanics, Volume 4: Proceedings of the 2012 Annual Conference on Experimental and Applied Mechanics, the fourth volume of seven from the Conference, brings together 54 contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Experimental and Applied Mechanics, including papers on:  Fracture & Fatigue Microscale & Microstructural Effects in Fatigue & Fracture Material Applications Composite Characterization Using Digital Image Correlation Techniques Multi-Scale Simulation and Testing of Composites Residual Stress Inverse Problems/Hybrid Methods Nano-Composites Microstructure Material Characterization Modeling and Uncertainty Quantification Impact Behavior of Composites.

Synthesis and characterization of large WO{sub 3} sheets synthesized by resistive heating method

Energy Technology Data Exchange (ETDEWEB)

Filippo, Emanuela, E-mail: emanuela.filippo@unisalento.it [Department of Engineering for Innovation, University of Salento, Monteroni Street, Lecce I-73100 Italy (Italy); Tepore, Marco [Department of Engineering for Innovation, University of Salento, Monteroni Street, Lecce I-73100 Italy (Italy); Baldassarre, Francesca [Department of Cultural Heritage, University of Salento, Lecce I-73100 Italy (Italy); Quarta, Gianluca; Calcagnile, Lucio [Department of Engineering for Innovation, University of Salento, Monteroni Street, Lecce I-73100 Italy (Italy); Guascito, Maria Rachele [DiSTeBA, University of Salento, Lecce I-73100 Italy (Italy); Tepore, Antonio [Department of Cultural Heritage, University of Salento, Lecce I-73100 Italy (Italy)

2015-09-01

A simple, low-cost method is presented to grow tungsten oxide large sheets simply by resistively heating a pure tungsten filament under air/water vapor flow. The obtained structures were studied using scanning and transmission electron microscopy, selected area diffraction, X Ray diffraction, Raman and X-ray photoelectron spectroscopy, photoluminescence and zeta potential measurements. SEM observations revealed that sheets formed by broadening of the wires/belts over longer growth period. Photoluminescence measurements showed that tungsten oxide sheets had an intense visible emission band. - Highlights: • WO{sub 3} large sheets were prepared by resistively heating a W filament. • WO{sub 3} sheets were carefully characterized. • Formation mechanism of sheets was studied. • WO{sub 3} sheets had an intense visible emission band at 462 nm.

Ageing of palladium tritide: mechanical characterization, helium state and modelling

International Nuclear Information System (INIS)

Segard, M.

2010-01-01

Palladium is commonly used for the storage of tritium (the hydrogen radioactive isotope), since it forms a low-equilibrium-pressure and reversible tritide. Tritium decay into helium-3 is responsible for the ageing of the tritide, leading to the apparition of helium-3 bubbles for instance. Both experimental and theoretical aspects of this phenomenon are studied here.Previous works on ageing modelling led to two main models, dealing with:- Helium-3 bubbles nucleation (using a cellular automaton), - Bubbles growth (using continuum mechanics).These models were quite efficient, but their use was limited by the lack of input data and fitting experimental parameters.To get through these limitations, this work has consisted in studying the most relevant experimental data to improve the modelling of the palladium tritide ageing.The first part of this work was focused on the assessment of the mechanical properties of the palladium tritide (yield strength, ultimate strength, mechanical behaviour). They were deduced from the in situ tensile tests performed on palladium hydride and deuteride. In the second part, ageing characterization was undertaken, mainly focusing on: - Bubbles observations in palladium tritide using transmission electron microscopy, - Internal bubble pressure measurements using nuclear magnetic resonance, - Macroscopic swelling measurements using pycno-metry.The present work has led to significant progress in ageing understanding and has brought very valuable improvements to the modelling of such a phenomenon. (author) [fr

Development and characterization of Al-Zn alloy by ingot metallurgy and powder metallurgy with improved mechanical properties

International Nuclear Information System (INIS)

Waseem, M.; Awais, H.B.; Zauha, M.S.; Tariq, N.H.

2007-01-01

Current project focuses on the production of AI-Zn alloy AA7075 used for wide range of applications like Aircraft components, missile and other structural applications. The above alloy was developed by two different routes. One was melting /casting, after which alloy was characterized by microstructural - examination (optical and SEM) and mechanical testing. Other route was the preparation of this alloy by powder metallurgy. This involves preparation of powders, mechanical alloying, compaction, sintering, rolling, solution treatment and aging then analysis. Powders of Aluminum, Zinc and powders of master alloys of AI-Cu, AI-Mg, AI-Mn, and AI-Cr were Mechanical alloyed. Then this powder was compacted by uniaxial press to form pellets. Sintering was carried out at 500 degree C and then hot rolled in Ar atmosphere. After solution and aging treatments samples were characterized. It is observed that there is about 12-21% improvement in mechanical properties such as tensile strength, yield strength, ductility and fracture toughness due to the more fine microstructure and less segregation than ingot metallurgy route. (author)

Lamb Wave Stiffness Characterization of Composites Undergoing Thermal-Mechanical Aging

Science.gov (United States)

Seale, Michael D.; Madaras, Eric I.

2004-01-01

The introduction of new, advanced composite materials into aviation systems requires a thorough understanding of the long term effects of combined thermal and mechanical loading upon those materials. Analytical methods investigating the effects of intense thermal heating combined with mechanical loading have been investigated. The damage mechanisms and fatigue lives were dependent on test parameters as well as stress levels. Castelli, et al. identified matrix dominated failure modes for out-of-phase cycling and fiber dominated damage modes for in-phase cycling. In recent years, ultrasonic methods have been developed that can measure the mechanical stiffness of composites. To help evaluate the effect of aging, a suitably designed Lamb wave measurement system is being used to obtain bending and out-of-plane stiffness coefficients of composite laminates undergoing thermal-mechanical loading. The system works by exciting an antisymmetric Lamb wave and calculating the velocity at each frequency from the known transducer separation and the measured time-of-flight. The same peak in the waveforms received at various distances is used to measure the time difference between the signals. The velocity measurements are accurate and repeatable to within 1% resulting in reconstructed stiffness values repeatable to within 4%. Given the material density and plate thickness, the bending and out-of-plane shear stiffnesses are calculated from a reconstruction of the dispersion curve. A mechanical scanner is used to move the sensors over the surface to map the time-of-flight, velocity, or stiffnesses of the entire specimen. Access to only one side of the material is required and no immersion or couplants are required because the sensors are dry coupled to the surface of the plate. In this study, the elastic stiffnesses D(sub 11), D(sub 22), A(sub 44), and A(sub 55) as well as time-of-flight measurements for composite samples that have undergone combined thermal and mechanical aging for

Investigation of the mechanism of iron acquisition by the marine bacterium Alteromonas luteoviolaceus: Characterization of siderophore production

International Nuclear Information System (INIS)

Reid, R.T.; Butler, A.

1991-01-01

Iron availability in the ocean ranges from one to four orders of magnitude below typical growth requirements of bacteria. The discrepancy between Fe availability and requirements raises questions about the mechanisms that marine bacteria use to sequester Fe 3+ . Surprisingly little is known about the siderophores produced by marine bacteria. Growth conditions of an open-ocean bacterial isolate, Alteromonas luteoviolaceus, were investigated to determine the conditions which enhance siderophore production. Methods to isolate and purify the siderophores were determined. The siderophores produced by A. luteoviolaceus were partially characterized by mass spectral analysis, amino acid analysis, qualitative analytical tests, chemical degradation, and nuclear magnetic resonance. A new set of outer membrane proteins was also produced when the bacterium was grown under Fe-limited conditions

Gelatinized and nongelatinized corn starch/ poly(epsilon-caprolactone) blends: characterization by rheological, mechanical and morphological properties

OpenAIRE

Rosa,Derval S.; Guedes,Cristina G. F.; Pedroso,Andréa G.

2004-01-01

Poly(epsilon-caprolactone)/corn starch blends containing 25, 50 and 75 wt.% starch were prepared by mechanical processing and characterized by the melt flow index (MFI), tensile test and scanning electron microscopy (SEM). For comparison, starch was used in gelatinized and nongelatinized forms and was also characterized by viscography. The addition of starch to poly(epsilon-caprolactone) reduced the MFI values, the tensile strength and the elongation at break, whereas the modulus increased. T...

Multiscale methods in computational fluid and solid mechanics

NARCIS (Netherlands)

Borst, de R.; Hulshoff, S.J.; Lenz, S.; Munts, E.A.; Brummelen, van E.H.; Wall, W.; Wesseling, P.; Onate, E.; Periaux, J.

2006-01-01

First, an attempt is made towards gaining a more systematic understanding of recent progress in multiscale modelling in computational solid and fluid mechanics. Sub- sequently, the discussion is focused on variational multiscale methods for the compressible and incompressible Navier-Stokes

Characterization of craniofacial sutures using the finite element method.

Science.gov (United States)

Maloul, Asmaa; Fialkov, Jeffrey; Wagner, Diane; Whyne, Cari M

2014-01-03

Characterizing the biomechanical behavior of sutures in the human craniofacial skeleton (CFS) is essential to understand the global impact of these articulations on load transmission, but is challenging due to the complexity of their interdigitated morphology, the multidirectional loading they are exposed to and the lack of well-defined suture material properties. This study aimed to quantify the impact of morphological features, direction of loading and suture material properties on the mechanical behavior of sutures and surrounding bone in the CFS. Thirty-six idealized finite element (FE) models were developed. One additional specimen-specific FE model was developed based on the morphology obtained from a µCT scan to represent the morphological complexity inherent in CFS sutures. Outcome variables of strain energy (SE) and von Mises stress (σvm) were evaluated to characterize the sutures' biomechanical behavior. Loading direction was found to impact the relationship between SE and interdigitation index and yielded varied patterns of σvm in both the suture and surrounding bone. Adding bone connectivity reduced suture strain energy and altered the σvm distribution. Incorporating transversely isotropic material properties was found to reduce SE, but had little impact on stress patterns. High-resolution µCT scanning of the suture revealed a complex morphology with areas of high and low interdigitations. The specimen specific suture model results were reflective of SE absorption and σvm distribution patterns consistent with the simplified FE results. Suture mechanical behavior is impacted by morphologic factors (interdigitation and connectivity), which may be optimized for regional loading within the CFS. © 2013 Elsevier Ltd. All rights reserved.

Characterization for elastic constants of fused deposition modelling-fabricated materials based on the virtual fields method and digital image correlation

Science.gov (United States)

Cao, Quankun; Xie, Huimin

2017-12-01

Fused deposition modelling (FDM), a widely used rapid prototyping process, is a promising technique in manufacturing engineering. In this work, a method for characterizing elastic constants of FDM-fabricated materials is proposed. First of all, according to the manufacturing process of FDM, orthotropic constitutive model is used to describe the mechanical behavior. Then the virtual fields method (VFM) is applied to characterize all the mechanical parameters (Q_{11}, Q_{22}, Q_{12}, Q_{66}) using the full-field strain, which is measured by digital image correlation (DIC). Since the principal axis of the FDM-fabricated structure is sometimes unknown due to the complexity of the manufacturing process, a disk in diametrical compression is used as the load configuration so that the loading angle can be changed conveniently. To verify the feasibility of the proposed method, finite element method (FEM) simulation is conducted to obtain the strain field of the disk. The simulation results show that higher accuracy can be achieved when the loading angle is close to 30°. Finally, a disk fabricated by FDM was used for the experiment. By rotating the disk, several tests with different loading angles were conducted. To determine the position of the principal axis in each test, two groups of parameters (Q_{11}, Q_{22}, Q_{12}, Q_{66}) are calculated by two different groups of virtual fields. Then the corresponding loading angle can be determined by minimizing the deviation between two groups of the parameters. After that, the four constants (Q_{11}, Q_{22}, Q_{12}, Q_{66}) were determined from the test with an angle of 27°.

Waste Characterization: Approaches and Methods

DEFF Research Database (Denmark)

Lagerkvist, A.; Ecke, H.; Christensen, Thomas Højlund

2011-01-01

Characterization of solid waste is usually a difficult task because of the heterogeneity of the waste and its spatial as well as temporal variations. This makes waste characterization costly if good and reliable data with reasonable uncertainty is to be obtained. Therefore, a waste characterization...... is often narrowly defined to meet specific needs for information. This may however limit the general usefulness of the information gained, for example, if the specific purpose limited the characterization to a subset of variables. In general, data available in the solid waste area are limited and often...... related to individual treatment processes and waste products are dealt with in the following chapters: Characteristic data on residential waste (Chapter 2.2), commercial and institutional waste (Chapter 2.3), industrial waste (Chapter 2.4) and construction and demolition waste (Chapter 2...

Quantitative data analysis methods for 3D microstructure characterization of Solid Oxide Cells

DEFF Research Database (Denmark)

Jørgensen, Peter Stanley

through percolating networks and reaction rates at the triple phase boundaries. Quantitative analysis of microstructure is thus important both in research and development of optimal microstructure design and fabrication. Three dimensional microstructure characterization in particular holds great promise...... for gaining further fundamental understanding of how microstructure affects performance. In this work, methods for automatic 3D characterization of microstructure are studied: from the acquisition of 3D image data by focused ion beam tomography to the extraction of quantitative measures that characterize...... the microstructure. The methods are exemplied by the analysis of Ni-YSZ and LSC-CGO electrode samples. Automatic methods for preprocessing the raw 3D image data are developed. The preprocessing steps correct for errors introduced by the image acquisition by the focused ion beam serial sectioning. Alignment...

Semi-automatic version of the potentiometric titration method for characterization of uranium compounds

International Nuclear Information System (INIS)

Cristiano, Bárbara F.G.; Delgado, José Ubiratan; Wanderley S da Silva, José; Barros, Pedro D. de; Araújo, Radier M.S. de; Dias, Fábio C.; Lopes, Ricardo T.

2012-01-01

The potentiometric titration method was used for characterization of uranium compounds to be applied in intercomparison programs. The method is applied with traceability assured using a potassium dichromate primary standard. A semi-automatic version was developed to reduce the analysis time and the operator variation. The standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization and compatible with those obtained by manual techniques. - Highlights: ► A semi-automatic potentiometric titration method was developed for U charaterization. ► K 2 Cr 2 O 7 was the only certified reference material used. ► Values obtained for U 3 O 8 samples were consistent with certified. ► Uncertainty of 0.01% was useful for characterization and intercomparison program.

Anisotropic Elastoplastic Damage Mechanics Method to Predict Fatigue Life of the Structure

Directory of Open Access Journals (Sweden)

Hualiang Wan

2016-01-01

Full Text Available New damage mechanics method is proposed to predict the low-cycle fatigue life of metallic structures under multiaxial loading. The microstructure mechanical model is proposed to simulate anisotropic elastoplastic damage evolution. As the micromodel depends on few material parameters, the present method is very concise and suitable for engineering application. The material parameters in damage evolution equation are determined by fatigue experimental data of standard specimens. By employing further development on the ANSYS platform, the anisotropic elastoplastic damage mechanics-finite element method is developed. The fatigue crack propagation life of satellite structure is predicted using the present method and the computational results comply with the experimental data very well.

A new method for the characterization of micro-/nano-periodic structures based on microscopic Moiré fringes

Energy Technology Data Exchange (ETDEWEB)

Wu, Dan; Xie, Huimin, E-mail: xiehm@mail.tsinghua.edu.cn; Tang, Minjin; Hu, Zhenxing

2014-01-15

Linewidth and opening ratio (ratio of linewidth to period) are important parameters in characterizing micro-/nano-periodic and quasi-periodic structures. Periodic structures are conventionally characterized by the direct observation of specimens under a microscope. However, the field of view is relatively small, and only certain details can be acquired under a microscope. Moreover, the non-uniformity of the linewidth in quasi-periodic structures cannot be detected. This paper proposes a new characterization method for determining the linewidth and opening ratio of periodic structures based on Moiré fringe analysis. This method has the advantage of full-field characterization of the linewidth of micro-/nano-structures over a larger area than that afforded by direct observation. To validate the method, the linewidth of scanning electron microscope (SEM) scan lines was first calibrated with a standard grating. Next, a microperiodic structure with known geometry was characterized using this calibrated SEM system. The results indicate that the proposed method is simple and effective, indicating a potential approach for the characterization of gratings over large areas. This technique can be extended to various high-power scanning microscopes to characterize micro-/nano-structures. - Highlights: • A characterization method of the linewidth of high frequency gratings based on the microscope Moiré fringes is introduced. • The principle is according to the geometrical relationship between the gratings and the Moiré fringes. • This method has the potential application in characterization of the micro-/nano-structures. • The advantage of this method is that the micro-/nano-structures can be characterized in large view field under the full field of the microscope. • The microstructure of a butterfly has been characterized to declare the feasibility of this method.

Mechanical and trybological characterization of ceramic materials obtained of mine solid wastes

International Nuclear Information System (INIS)

Soto T, J.L.

2003-01-01

A discussion of the physical, mechanical and tribological characterization of the ceramics Jaar, Jaca and Vijaar is presented in this work. They have been obtained from the industrial residuals, coming from metals and sand of the mining industry in Pachuca Hidalgo, Mexico. The methodology followed for the obtention and characterization of these ceramics consists on eliminating the cyanides from the tailings through columns coupled with a system controlled with thermostats. Then, the chemical composition is analysed with spectrometry emission of plasma and scanning electronic microscopy. Then the ceramics are produced. The base material is agglutinated with clay or kaolin. For this purpose, it was used a sintering processes and isothermal compacting in hot condition. Finally, the physical, chemical, mechanical and tribological properties of these new products are determined. Carbon, oxygen, sodium, magnesium, aluminium, manganese, silicon, potassium, phosphor, calcium, titanium, iron, molybdenum, silver and gold are in the chemical composition or ceramic analysed. Also these are heterogeneous mixture of clay and kaolin. The cyanide was eliminated. The results show that Vijaar has better wear resistances to the waste; this was demonstrated in tribology tests. They were not perforated with the abrasive particles. Also, they have high hardness and they can to support more loads in compression than Jaar and the Jaca. Consequently, they are less fragile and, therefore, they can tolerate bending stresses and bigger impact loading. (Author)

The mechanical spectra of deposited materials by a composite reed vibration method

International Nuclear Information System (INIS)

Ying, X.N.; Zhang, L.; Yuan, Y.H.

2010-01-01

Recently a composite reed vibration method has been designed to measure the mechanical spectra (complex Young's modulus) of materials from liquid to solid state. The mechanical spectra of materials can be obtained from a composite system consisting of a substrate reed and of materials deposited on it. In this report, two sets of formulas to calculate the mechanical spectra of deposited materials are further analyzed. The proof is given for the previous named 'approximate formulas' (labeled as Formula II). Then the composite reed vibration method can be safely used as an extension of the mechanical spectrum method of the thin solid film. At the same time, some comments are made on previous analytical formulas (labeled as Formula I). At last, more experiments with a small amount of deposited materials are performed. It is found that smaller quantity is more favorable to achieve the intrinsic mechanical spectra of deposited materials.

Mechanical Characterization and Finite Element Analysis of Jute-Epoxy Composite

Directory of Open Access Journals (Sweden)

Sangamesh Rajole

2018-01-01

Full Text Available Natural fiber composite materials are such an appropriate material, that replaces synthetic composite materials for many of practical applications where we need high strength and low density. Natural fiber composites combine the technological, ecological and economical aspects. This leads to discovering its vast applications in the aeronautics, automotive, marine and sporting sectors. This paper deals with the study on mechanical characterization (Tensile, Compression and Flexural of jute/epoxy (JE polymer composite. The flexural properties of composites are experimentally tested and are simulated in commercially available FEA software. Flexural tested results are in good agreement with FEA results. Scanning electron microscopy (SEM analysis of the failed samples reveals the matrix dominated failure.

Characterization of the anisotropic mechanical behavior of human abdominal wall connective tissues.

Science.gov (United States)

Astruc, Laure; De Meulaere, Maurice; Witz, Jean-François; Nováček, Vit; Turquier, Frédéric; Hoc, Thierry; Brieu, Mathias

2018-06-01

Abdominal wall sheathing tissues are commonly involved in hernia formation. However, there is very limited work studying mechanics of all tissues from the same donor which prevents a complete understanding of the abdominal wall behavior and the differences in these tissues. The aim of this study was to investigate the differences between the mechanical properties of the linea alba and the anterior and posterior rectus sheaths from a macroscopic point of view. Eight full-thickness human anterior abdominal walls of both genders were collected and longitudinal and transverse samples were harvested from the three sheathing connective tissues. The total of 398 uniaxial tensile tests was conducted and the mechanical characteristics of the behavior (tangent rigidities for small and large deformations) were determined. Statistical comparisons highlighted heterogeneity and non-linearity in behavior of the three tissues under both small and large deformations. High anisotropy was observed under small and large deformations with higher stress in the transverse direction. Variabilities in the mechanical properties of the linea alba according to the gender and location were also identified. Finally, data dispersion correlated with microstructure revealed that macroscopic characterization is not sufficient to fully describe behavior. Microstructure consideration is needed. These results provide a better understanding of the mechanical behavior of the abdominal wall sheathing tissues as well as the directions for microstructure-based constitutive model. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mathematical methods in quantum and statistical mechanics

International Nuclear Information System (INIS)

Fishman, L.

1977-01-01

The mathematical structure and closed-form solutions pertaining to several physical problems in quantum and statistical mechanics are examined in some detail. The J-matrix method, introduced previously for s-wave scattering and based upon well-established Hilbert Space theory and related generalized integral transformation techniques, is extended to treat the lth partial wave kinetic energy and Coulomb Hamiltonians within the context of square integrable (L 2 ), Laguerre (Slater), and oscillator (Gaussian) basis sets. The theory of relaxation in statistical mechanics within the context of the theory of linear integro-differential equations of the Master Equation type and their corresponding Markov processes is examined. Several topics of a mathematical nature concerning various computational aspects of the L 2 approach to quantum scattering theory are discussed

Engineering Change Management Method Framework in Mechanical Engineering

Science.gov (United States)

Stekolschik, Alexander

2016-11-01

Engineering changes make an impact on different process chains in and outside the company, and lead to most error costs and time shifts. In fact, 30 to 50 per cent of development costs result from technical changes. Controlling engineering change processes can help us to avoid errors and risks, and contribute to cost optimization and a shorter time to market. This paper presents a method framework for controlling engineering changes at mechanical engineering companies. The developed classification of engineering changes and accordingly process requirements build the basis for the method framework. The developed method framework comprises two main areas: special data objects managed in different engineering IT tools and process framework. Objects from both areas are building blocks that can be selected to the overall business process based on the engineering process type and change classification. The process framework contains steps for the creation of change objects (both for overall change and for parts), change implementation, and release. Companies can select singleprocess building blocks from the framework, depending on the product development process and change impact. The developed change framework has been implemented at a division (10,000 employees) of a big German mechanical engineering company.

Microstructural and mechanical characterization of the ferritic martensitic steel eurofer'97 after simulated service conditions

International Nuclear Information System (INIS)

Fernandez, P.; Lancha, A. M.; Lapena, J.

2002-01-01

This report details the metallurgical characterization of the Eurofer'97 steel thermally aged in the range of temperatures from 400 degree centigrade to 600 degree centigrade up to 10000 H, microstructural studies and mechanical testing (hardness, tensile, Charpy and low cycle fatigue test) have been carried out

A task specific uncertainty analysis method for least-squares-based form characterization of ultra-precision freeform surfaces

International Nuclear Information System (INIS)

Ren, M J; Cheung, C F; Kong, L B

2012-01-01

In the measurement of ultra-precision freeform surfaces, least-squares-based form characterization methods are widely used to evaluate the form error of the measured surfaces. Although many methodologies have been proposed in recent years to improve the efficiency of the characterization process, relatively little research has been conducted on the analysis of associated uncertainty in the characterization results which may result from those characterization methods being used. As a result, this paper presents a task specific uncertainty analysis method with application in the least-squares-based form characterization of ultra-precision freeform surfaces. That is, the associated uncertainty in the form characterization results is estimated when the measured data are extracted from a specific surface with specific sampling strategy. Three factors are considered in this study which include measurement error, surface form error and sample size. The task specific uncertainty analysis method has been evaluated through a series of experiments. The results show that the task specific uncertainty analysis method can effectively estimate the uncertainty of the form characterization results for a specific freeform surface measurement

Multiscale experimental mechanics of hierarchical carbon-based materials.

Science.gov (United States)

Espinosa, Horacio D; Filleter, Tobin; Naraghi, Mohammad

2012-06-05

Investigation of the mechanics of natural materials, such as spider silk, abalone shells, and bone, has provided great insight into the design of materials that can simultaneously achieve high specific strength and toughness. Research has shown that their emergent mechanical properties are owed in part to their specific self-organization in hierarchical molecular structures, from nanoscale to macroscale, as well as their mixing and bonding. To apply these findings to manmade materials, researchers have devoted significant efforts in developing a fundamental understanding of multiscale mechanics of materials and its application to the design of novel materials with superior mechanical performance. These efforts included the utilization of some of the most promising carbon-based nanomaterials, such as carbon nanotubes, carbon nanofibers, and graphene, together with a variety of matrix materials. At the core of these efforts lies the need to characterize material mechanical behavior across multiple length scales starting from nanoscale characterization of constituents and their interactions to emerging micro- and macroscale properties. In this report, progress made in experimental tools and methods currently used for material characterization across multiple length scales is reviewed, as well as a discussion of how they have impacted our current understanding of the mechanics of hierarchical carbon-based materials. In addition, insight is provided into strategies for bridging experiments across length scales, which are essential in establishing a multiscale characterization approach. While the focus of this progress report is in experimental methods, their concerted use with theoretical-computational approaches towards the establishment of a robust material by design methodology is also discussed, which can pave the way for the development of novel materials possessing unprecedented mechanical properties. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Elastic Characterization of Transversely Isotropic Soft Materials by Dynamic Shear and Asymmetric Indentation

OpenAIRE

Namani, R.; Feng, Y.; Okamoto, R. J.; Jesuraj, N.; Sakiyama-Elbert, S. E.; Genin, G. M.; Bayly, P. V.

2012-01-01

The mechanical characterization of soft anisotropic materials is a fundamental challenge because of difficulties in applying mechanical loads to soft matter and the need to combine information from multiple tests. A method to characterize the linear elastic properties of transversely isotropic soft materials is proposed, based on the combination of dynamic shear testing (DST) and asymmetric indentation. The procedure was demonstrated by characterizing a nearly incompressible transversely isot...

Teaching fluid mechanics to high schoolers: methods, challenges, and outcome

Science.gov (United States)

Manikantan, Harishankar

2017-11-01

This talk will summarize the goals, methods, and both short- and long-term feedback from two high-school-level courses in fluid mechanics involving 43 students and cumulatively spanning over 100 hours of instruction. The goals of these courses were twofold: (a) to spark an interest in science and engineering and attract a more diverse demographic into college-level STEM programs; and (b) to train students in a `college-like' method of approaching the physics of common phenomena, with fluid mechanics as the context. The methods of instruction included classes revolving around the idea of dispelling misconceptions, group activities, `challenge' rounds and mock design projects to use fluid mechanics phenomena to achieve a specified goal, and simple hands-on experiments. The feedback during instruction was overwhelmingly positive, particularly in terms of a changing and favorable attitude towards math and engineering. Long after the program, a visible impact lies in a diverse group of students acknowledging that the course had a positive effect in their decision to choose an engineering or science major in a four-year college.

A Modified Water-Table Fluctuation Method to Characterize Regional Groundwater Discharge

Directory of Open Access Journals (Sweden)

Lihong Yang

2018-04-01

Full Text Available A modified Water-Table Fluctuation (WTF method is developed to quantitatively characterize the regional groundwater discharge patterns in stressed aquifers caused by intensive agricultural pumping. Two new parameters are defined to express the secondary information in the observed data. One is infiltration efficiency and the other is discharge modulus (recurring head loss due to aquifer discharge. An optimization procedure is involved to estimate these parameters, based on continuous groundwater head measurements and precipitation records. Using the defined parameters and precipitation time series, water level changes are calculated for individual wells with fidelity. The estimated parameters are then used to further address the characterization of infiltration and to better quantify the discharge at the regional scale. The advantage of this method is that it considers recharge and discharge simultaneously, whereas the general WTF methods mostly focus on recharge. In the case study, the infiltration efficiency reveals that the infiltration is regionally controlled by the intrinsic characteristics of the aquifer, and locally distorted by engineered hydraulic structures that alter surface water-groundwater interactions. The seasonality of groundwater discharge is characterized by the monthly discharge modulus. These results from individual wells are clustered into groups that are consistent with the local land use pattern and cropping structures.

An optical method for characterizing carbon content in ceramic pot filters.

Science.gov (United States)

Goodwin, J Y; Elmore, A C; Salvinelli, C; Reidmeyer, Mary R

2017-08-01

Ceramic pot filter (CPF) technology is a relatively common means of household water treatment in developing areas, and performance characteristics of CPFs have been characterized using production CPFs, experimental CPFs fabricated in research laboratories, and ceramic disks intended to be CPF surrogates. There is evidence that CPF manufacturers do not always fire their products according to best practices and the result is incomplete combustion of the pore forming material and the creation of a carbon core in the final CPFs. Researchers seldom acknowledge the existence of potential existence of carbon cores, and at least one CPF producer has postulated that the carbon may be beneficial in terms of final water quality because of the presence of activated carbon in consumer filters marketed in the Western world. An initial step in characterizing the presence and impact of carbon cores is the characterization of those cores. An optical method which may be more viable to producers relative to off-site laboratory analysis of carbon content has been developed and verified. The use of the optical method is demonstrated via preliminary disinfection and flowrate studies, and the results of these studies indicate that the method may be of use in studying production kiln operation.

Theoretical physics 7 quantum mechanics : methods and applications

CERN Document Server

Nolting, Wolfgang

2017-01-01

This textbook offers a clear and comprehensive introduction to methods and applications in quantum mechanics, one of the core components of undergraduate physics courses. It follows on naturally from the previous volumes in this series, thus developing the understanding of quantized states further on. The first part of the book introduces the quantum theory of angular momentum and approximation methods. More complex themes are covered in the second part of the book, which describes multiple particle systems and scattering theory. Ideally suited to undergraduate students with some grounding in the basics of quantum mechanics, the book is enhanced throughout with learning features such as boxed inserts and chapter summaries, with key mathematical derivations highlighted to aid understanding. The text is supported by numerous worked examples and end of chapter problem sets.  About the Theoretical Physics series Translated from the renowned and highly successful German editions, the eight volumes of this seri...

Comparative study of fracture mechanical test methods for concrete

DEFF Research Database (Denmark)

Østergaard, Lennart; Olesen, John Forbes

2004-01-01

and the interpretation, i.e. the analysis needed to extract the stress-crack opening relationship, the fracture energy etc. Experiments are carried out with each test configuration using mature, high performance concrete. The results show that the UTT is a highly complicated test, which only under very well controlled...... circumstances will yield the true fracture mechanical properties. It is also shown that both the three point bending test and the WST are well-suited substitutes for the uniaxial tension test.......This paper describes and compares three different fracture mechanical test methods; the uniaxial tension test (UTT), the three point bending test (TPBT) and the wedge splitting test (WST). Potentials and problems with the test methods will be described with regard to the experiment...

Microstructures and formation mechanism of W–Cu composite coatings on copper substrate prepared by mechanical alloying method

International Nuclear Information System (INIS)

Meng, Yunfei; Shen, Yifu; Chen, Cheng; Li, Yongcan; Feng, Xiaomei

2013-01-01

In the present work, high-energy mechanical alloying (MA) method was applied to prepare tungsten–copper composite coatings on pure copper surface using a planetary ball mill. During mechanical alloying process, grains on the surface layer of substrate were refined and the substrate surface was activated as a result of repeated collisions by a large number of flying balls along with powder particles. The repeated ball-to-substrate collisions resulted in the deposition of coatings. The microstructures and elemental and phase composition of mechanically alloyed coatings at different milling durations during mechanical alloying process were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS). Microhardness tests were carried out to examine the mechanical properties of the coatings. The results showed that the coatings and the substrates were well bonded, and with the increase of the milling duration, multi-layered coatings with different structures were generated and the coatings became denser. The microhardness tests showed that the maximum microhardness of the coatings reached HV 0.1 228, showing a threefold improvement upon the substrate. And the cross-sectional microhardness values of the processed sample changed gradually, which gave a proof for the cushioning and sustaining functions of the multi-layered coatings. A reasonable formation mechanism of coatings on bulk materials with metallic immiscible system by mechanical alloying method was presented.

The variational method in quantum mechanics: an elementary introduction

Science.gov (United States)

Borghi, Riccardo

2018-05-01

Variational methods in quantum mechanics are customarily presented as invaluable techniques to find approximate estimates of ground state energies. In the present paper a short catalogue of different celebrated potential distributions (both 1D and 3D), for which an exact and complete (energy and wavefunction) ground state determination can be achieved in an elementary way, is illustrated. No previous knowledge of calculus of variations is required. Rather, in all presented cases the exact energy functional minimization is achieved by using only a couple of simple mathematical tricks: ‘completion of square’ and integration by parts. This makes our approach particularly suitable for undergraduates. Moreover, the key role played by particle localization is emphasized through the entire analysis. This gentle introduction to the variational method could also be potentially attractive for more expert students as a possible elementary route toward a rather advanced topic on quantum mechanics: the factorization method. Such an unexpected connection is outlined in the final part of the paper.

A variationally coupled FE-BE method for elasticity and fracture mechanics

Science.gov (United States)

Lu, Y. Y.; Belytschko, T.; Liu, W. K.

1991-01-01

A new method for coupling finite element and boundary element subdomains in elasticity and fracture mechanics problems is described. The essential feature of this new method is that a single variational statement is obtained for the entire domain, and in this process the terms associated with tractions on the interfaces between the subdomains are eliminated. This provides the additional advantage that the ambiguities associated with the matching of discontinuous tractions are circumvented. The method leads to a direct procedure for obtaining the discrete equations for the coupled problem without any intermediate steps. In order to evaluate this method and compare it with previous methods, a patch test for coupled procedures has been devised. Evaluation of this variationally coupled method and other methods, such as stiffness coupling and constraint traction matching coupling, shows that this method is substantially superior. Solutions for a series of fracture mechanics problems are also reported to illustrate the effectiveness of this method.

Application of radiological imaging methods to radioactive waste characterization

Energy Technology Data Exchange (ETDEWEB)

Tessaro, Ana Paula Gimenes; Souza, Daiane Cristini B. de; Vicente, Roberto, E-mail: aptessaro@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2013-07-01

Radiological imaging technologies are most frequently used for medical diagnostic purposes but are also useful in materials characterization and other non-medical applications in research and industry. The characterization of radioactive waste packages or waste samples can also benefit from these techniques. In this paper, the application of some imaging methods is examined for the physical characterization of radioactive wastes constituted by spent ion-exchange resins and activated charcoal beds stored at the Radioactive Waste Management Department of IPEN. These wastes are generated when the filter media of the water polishing system of the IEA-R1 Nuclear Research Reactor is no longer able to maintain the required water quality and are replaced. The IEA-R1 is a 5MW pool-type reactor, moderated and cooled by light water, and fission and activation products released from the reactor core must be continuously removed to prevent activity buildup in the water. The replacement of the sorbents is carried out by pumping from the filter tanks into several 200 L drums, each drum getting a variable amount of water. Considering that the results of radioanalytical methods to determine the concentrations of radionuclides are usually expressed on dry basis,the amount of water must be known to calculate the total activity of each package. At first sight this is a trivial problem that demanded, however some effort to be solved. The findings on this subject are reported in this paper. (author)

Mechanical characterization and structural analysis of recycled fiber-reinforced-polymer resin-transfer-molded beams

Science.gov (United States)

Tan, Eugene Wie Loon

1999-09-01

The present investigation was focussed on the mechanical characterization and structural analysis of resin-transfer-molded beams containing recycled fiber-reinforced polymers. The beams were structurally reinforced with continuous unidirectional glass fibers. The reinforcing filler materials consisted entirely of recycled fiber-reinforced polymer wastes (trim and overspray). The principal resin was a 100-percent dicyclo-pentadiene unsaturated polyester specially formulated with very low viscosity for resin transfer molding. Variations of the resin transfer molding technique were employed to produce specimens for material characterization. The basic materials that constituted the structural beams, continuous-glass-fiber-reinforced, recycled-trim-filled and recycled-overspray-filled unsaturated polyesters, were fully characterized in axial and transverse compression and tension, and inplane and interlaminar shear, to ascertain their strengths, ultimate strains, elastic moduli and Poisson's ratios. Experimentally determined mechanical properties of the recycled-trim-filled and recycled-overspray-filled materials from the present investigation were superior to those of unsaturated polyester polymer concretes and Portland cement concretes. Mechanical testing and finite element analyses of flexure (1 x 1 x 20 in) and beam (2 x 4 x 40 in) specimens were conducted. These structurally-reinforced specimens were tested and analyzed in four-point, third-point flexure to determine their ultimate loads, maximum fiber stresses and mid-span deflections. The experimentally determined load capacities of these specimens were compared to those of equivalent steel-reinforced Portland cement concrete beams computed using reinforced concrete theory. Mechanics of materials beam theory was utilized to predict the ultimate loads and mid-span deflections of the flexure and beam specimens. However, these predictions proved to be severely inadequate. Finite element (fracture propagation

Physical-mechanical and anatomical characterization in 26-year-old Eucalyptus resinifera wood

OpenAIRE

Lima,Israel Luiz de; Longui,Eduardo Luiz; Freitas,Miguel Luiz Menezes; Zanatto,Antonio Carlos Scatena; Zanata,Marcelo; Florsheim,Sandra Monteiro Borges; Bortoletto Jr.,Geraldo

2014-01-01

In the present study, we aimed to characterize Eucalyptus resinifera wood through physical and mechanical assays and wood anatomy studies, as well as determine the relationships between the properties and anatomy of wood. We used samples collected from the area close to the bark of ten 26-year-old E. resinifera trees. We concluded that the specific gravity (Gb), compression (f c0), and shear parallel to grain (f v0) were ranked in strength classes C30, C40 and C60, respectively, and that volu...

Method for the mechanical axis alignment of the linear induction accelerator

International Nuclear Information System (INIS)

Li Hong; China Academy of Engineering Physics, Mianyang; Yao Jin; Liu Yunlong; Zhang Linwen; Deng Jianjun

2004-01-01

Accurate mechanical axis alignment is a basic requirement for assembling a linear induction accelerator (LIA). The total length of an LIA is usually over thirty or fifty meters, and it consists of many induction cells. By using a laser tracker a new method of mechanical axis alignment for LIA is established to achieve the high accuracy. This paper introduces the method and gives implementation step and point position measure errors of the mechanical axis alignment. During the alignment process a 55 m-long alignment control survey net is built, and the theoretic revision of the coordinate of the control survey net is presented. (authors)

Mechanical characterization of structurally porous biomaterials built via additive manufacturing: experiments, predictive models, and design maps for load-bearing bone replacement implants.

Science.gov (United States)

Melancon, D; Bagheri, Z S; Johnston, R B; Liu, L; Tanzer, M; Pasini, D

2017-11-01

Porous biomaterials can be additively manufactured with micro-architecture tailored to satisfy the stringent mechano-biological requirements imposed by bone replacement implants. In a previous investigation, we introduced structurally porous biomaterials, featuring strength five times stronger than commercially available porous materials, and confirmed their bone ingrowth capability in an in vivo canine model. While encouraging, the manufactured biomaterials showed geometric mismatches between their internal porous architecture and that of its as-designed counterpart, as well as discrepancies between predicted and tested mechanical properties, issues not fully elucidated. In this work, we propose a systematic approach integrating computed tomography, mechanical testing, and statistical analysis of geometric imperfections to generate statistical based numerical models of high-strength additively manufactured porous biomaterials. The method is used to develop morphology and mechanical maps that illustrate the role played by pore size, porosity, strut thickness, and topology on the relations governing their elastic modulus and compressive yield strength. Overall, there are mismatches between the mechanical properties of ideal-geometry models and as-manufactured porous biomaterials with average errors of 49% and 41% respectively for compressive elastic modulus and yield strength. The proposed methodology gives more accurate predictions for the compressive stiffness and the compressive strength properties with a reduction of the average error to 11% and 7.6%. The implications of the results and the methodology here introduced are discussed in the relevant biomechanical and clinical context, with insight that highlights promises and limitations of additively manufactured porous biomaterials for load-bearing bone replacement implants. In this work, we perform mechanical characterization of load-bearing porous biomaterials for bone replacement over their entire design

An adaptive multi-element probabilistic collocation method for statistical EMC/EMI characterization

KAUST Repository

Yücel, Abdulkadir C.

2013-12-01

An adaptive multi-element probabilistic collocation (ME-PC) method for quantifying uncertainties in electromagnetic compatibility and interference phenomena involving electrically large, multi-scale, and complex platforms is presented. The method permits the efficient and accurate statistical characterization of observables (i.e., quantities of interest such as coupled voltages) that potentially vary rapidly and/or are discontinuous in the random variables (i.e., parameters that characterize uncertainty in a system\\'s geometry, configuration, or excitation). The method achieves its efficiency and accuracy by recursively and adaptively dividing the domain of the random variables into subdomains using as a guide the decay rate of relative error in a polynomial chaos expansion of the observables. While constructing local polynomial expansions on each subdomain, a fast integral-equation-based deterministic field-cable-circuit simulator is used to compute the observable values at the collocation/integration points determined by the adaptive ME-PC scheme. The adaptive ME-PC scheme requires far fewer (computationally costly) deterministic simulations than traditional polynomial chaos collocation and Monte Carlo methods for computing averages, standard deviations, and probability density functions of rapidly varying observables. The efficiency and accuracy of the method are demonstrated via its applications to the statistical characterization of voltages in shielded/unshielded microwave amplifiers and magnetic fields induced on car tire pressure sensors. © 2013 IEEE.

Analytical method for the isotopic characterization of soils

International Nuclear Information System (INIS)

Sibello Hernandez, Rita; Cozzella, Maria Letizia; Mariani, Mario

2014-01-01

The aim of this work was to develop an analytical method in order to determine the isotopic composition of different elements in soil samples and to determine the existence of contamination. The method used in the digestion of the samples was the EPA 3050B, and some metal concentration were determined including uranium and thorium. For elements with even lower concentrations such as plutonium and radium a treatment after mineralization by EPA, was necessary. The measurement technique used was mass spectrometry with quadrupole and plasma induced associated (ICP-MS). Results of the analysis performed in two laboratories showed a good correspondence. This method allowed to perform the isotopic characterization of studied soils and results showed that the studied soils do not present any local pollution and that the presence of plutonium-239, is due to global failure

Boiling anomaly detection by various signal characterization methods

International Nuclear Information System (INIS)

Sakuma, M.; Kozma, R.; Kitamura, M.; Schoonewelle, H.; Hoogenboom, J.E.

1996-01-01

In order to detect anomalies in the early stage for complex dynamical systems like nuclear power plants, it is important to characterize various statistical features of the data acquired in normal operating condition. In this paper, concept of hierarchical anomaly monitoring method is outlined, which is based on the diversification principle. In addition to usual time and frequency domain analysis (FFT, APDF, MAR-SPRT), other analysis (wavelet, fractal, etc.) are performed. As soon as any inconsistency arises in the results of the analysis on the upper level, a thorough analysis is initiated. A comparison among these methods is performed and the efficiency of the diversification approach has been demonstrated through simulated boiling anomalies in nuclear reactors. (authors)

A method of meta-mechanism combination and replacement based on motion study

Directory of Open Access Journals (Sweden)

Yadong Fang

2015-01-01

Full Text Available Lacking the effective methods to reduce labor and cost, many small- and medium-sized assembly companies are facing with the problem of high cost for a long time. In order to reduce costs of manual operations, the method of meta-mechanism combination and replacement is studied. In this paper, we mainly discuss assembling motion analysis, workpieces position information acquisition, motion library construction, assembling motion analysis by Maynard’s operation sequence technique, meta-mechanism database establishment, and match of motion and mechanism. At the same time, the principle, process, and system realization framework of mechanism replacement are introduced. Lastly, problems for low-cost automation of the production line are basically resolved by operator motion analysis and meta-mechanism combination and match.

Application of SBRA Method in Mechanics of Continetal Plates

Directory of Open Access Journals (Sweden)

Ivo WANDROL

2012-06-01

Full Text Available This paper shows the probabilistic SBRA Method application to the model of the behaviour of the lithosphere of the Earth. The method extends our initial work where we created the geomechanical model of the lithosphere. The basic idea was about the generation of thermoelastic waves due to thermal expansion of the rock mass and the ratcheting mechanisms.

Properties and characterization of modern materials

CERN Document Server

Altenbach, Holm

2017-01-01

This book focuses on robust characterization and prediction methods for materials in technical applications as well as the materials’ safety features during operation. In particular, it presents methods for reliably predicting material properties, an aspect that is becoming increasingly important as engineering materials are pushed closer and closer to their limits to boost the performance of machines and structures. To increase their engineering value, components are now designed under the consideration of their multiphysical properties and functions, which requires much more intensive investigation and characterization of these materials. The materials covered in this monograph range from metal-based groups such as lightweight alloys, to advanced high-strength steels and modern titanium alloys. Furthermore, a wide range of polymers and composite materials (e.g. with micro- and nanoparticles or fibres) is covered. The book explores methods for property prediction from classical mechanical characterization-...

Mechanical characterization of disordered and anisotropic cellular monolayers

Science.gov (United States)

Nestor-Bergmann, Alexander; Johns, Emma; Woolner, Sarah; Jensen, Oliver E.

2018-05-01

We consider a cellular monolayer, described using a vertex-based model, for which cells form a spatially disordered array of convex polygons that tile the plane. Equilibrium cell configurations are assumed to minimize a global energy defined in terms of cell areas and perimeters; energy is dissipated via dynamic area and length changes, as well as cell neighbor exchanges. The model captures our observations of an epithelium from a Xenopus embryo showing that uniaxial stretching induces spatial ordering, with cells under net tension (compression) tending to align with (against) the direction of stretch, but with the stress remaining heterogeneous at the single-cell level. We use the vertex model to derive the linearized relation between tissue-level stress, strain, and strain rate about a deformed base state, which can be used to characterize the tissue's anisotropic mechanical properties; expressions for viscoelastic tissue moduli are given as direct sums over cells. When the base state is isotropic, the model predicts that tissue properties can be tuned to a regime with high elastic shear resistance but low resistance to area changes, or vice versa.

Capsule-like {alpha}-Fe{sub 2}O{sub 3} nanoparticles: Synthesis, characterization, and growth mechanism

Energy Technology Data Exchange (ETDEWEB)

Su, Changhua [College of Materials Science and Engineering, Liaocheng University (China); Wang, Hui [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi' an (China)

2012-08-15

Uniform capsule-like {alpha}-Fe{sub 2}O{sub 3} particles were synthesized via a simple hydrothermal method, employing FeCl{sub 3} and CH{sub 3}COONa as the precursors and sodium dodecyl sulfate (SDS) as soft template. X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy were used to characterize the structure of synthesized products. Some factors influencing the formation of capsule-like {alpha}-Fe{sub 2}O{sub 3} particles were systematically investigated, including different kinds of surfactants, the concentration of SDS, and reaction times. The investigation on the evolution formation reveals that SDS was critical to control the morphology of final products, and a possible five-step growth mechanism was presented by tracking the structures of the products at different reaction stages. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Skin mechanical properties and modeling: A review.

Science.gov (United States)

Joodaki, Hamed; Panzer, Matthew B

2018-04-01

The mechanical properties of the skin are important for various applications. Numerous tests have been conducted to characterize the mechanical behavior of this tissue, and this article presents a review on different experimental methods used. A discussion on the general mechanical behavior of the skin, including nonlinearity, viscoelasticity, anisotropy, loading history dependency, failure properties, and aging effects, is presented. Finally, commonly used constitutive models for simulating the mechanical response of skin are discussed in the context of representing the empirically observed behavior.

Method for Determining the Time Constants Characterizing the Intensity of Steel Mixing in Continuous Casting Tundish

Directory of Open Access Journals (Sweden)

Pieprzyca J.

2015-04-01

Full Text Available A common method used in identification of hydrodynamics phenomena occurring in Continuous Casting (CC device's tundish is to determine the RTD curves of time. These curves allows to determine the way of the liquid steel flowing and mixing in the tundish. These can be identified either as the result of numerical simulation or by the experiments - as the result of researching the physical models. Special problem is to objectify it while conducting physical research. It is necessary to precisely determine the time constants which characterize researched phenomena basing on the data acquired in the measured change of the concentration of the tracer in model liquid's volume. The mathematical description of determined curves is based on the approximate differential equations formulated in the theory of fluid mechanics. Solving these equations to calculate the time constants requires a special software and it is very time-consuming. To improve the process a method was created to calculate the time constants with use of automation elements. It allows to solve problems using algebraic method, which improves interpretation of the research results of physical modeling.

A probabilistic approach to rock mechanical property characterization for nuclear waste repository design

International Nuclear Information System (INIS)

Kim, Kunsoo; Gao, Hang

1996-01-01

A probabilistic approach is proposed for the characterization of host rock mechanical properties at the Yucca Mountain site. This approach helps define the probability distribution of rock properties by utilizing extreme value statistics and Monte Carlo simulation. We analyze mechanical property data of tuff obtained by the NNWSI Project to assess the utility of the methodology. The analysis indicates that laboratory measured strength and deformation data of Calico Hills and Bullfrog tuffs follow an extremal. probability distribution (the third type asymptotic distribution of the smallest values). Monte Carlo simulation is carried out to estimate rock mass deformation moduli using a one-dimensional tuff model proposed by Zimmermann and Finley. We suggest that the results of these analyses be incorporated into the repository design

Radiolysis: an efficient method of studying radicalar antioxidant mechanisms

International Nuclear Information System (INIS)

Gardes-Albert, M.; Jore, D.

1998-01-01

The use of the radiolysis method for studying radicalar antioxidant mechanisms offers the different following possibilities: 1- quantitative evaluation of antioxidant activity of molecules soluble in aqueous or non aqueous media (oxidation yields, molecular mechanisms, rate constants), 2- evaluation of the yield of prevention towards polyunsaturated fatty acids peroxidation, 3- evaluation of antioxidant activity towards biological systems such as liposomes or low density lipoproteins (LDL), 4- simple comparison in different model systems of drags effect versus natural antioxidants. (authors)

Shallow Reflection Method for Water-Filled Void Detection and Characterization

Science.gov (United States)

Zahari, M. N. H.; Madun, A.; Dahlan, S. H.; Joret, A.; Hazreek, Z. A. M.; Mohammad, A. H.; Izzaty, R. A.

2018-04-01

Shallow investigation is crucial in enhancing the characteristics of subsurface void commonly encountered in civil engineering, and one such technique commonly used is seismic-reflection technique. An assessment of the effectiveness of such an approach is critical to determine whether the quality of the works meets the prescribed requirements. Conventional quality testing suffers limitations including: limited coverage (both area and depth) and problems with resolution quality. Traditionally quality assurance measurements use laboratory and in-situ invasive and destructive tests. However geophysical approaches, which are typically non-invasive and non-destructive, offer a method by which improvement of detection can be measured in a cost-effective way. Of this seismic reflection have proved useful to assess void characteristic, this paper evaluates the application of shallow seismic-reflection method in characterizing the water-filled void properties at 0.34 m depth, specifically for detection and characterization of void measurement using 2-dimensional tomography.

Microstructural and mechanical property characterization of Er modified Al-Mg-Mn alloy Tungsten Inert Gas welds

International Nuclear Information System (INIS)

Yang, Dongxia; Li, Xiaoyan; He, Dingyong; Nie, Zuoren; Huang, Hui

2012-01-01

Highlights: → The microstructural characterization of TIG welded Al-Mg-Mn-Zr-Er alloy is studied. → A typical equaixed zone (EQZ) with finer grains is observed in the weld metal at the fusion boundary. → The dissolution of non-primary Al 3 Er particles in Al matrix is one reason of the weakness of TIG welded joint. →The relationship between mechanical properties and microstructure of welded joints is evaluated. →Reasons for joint softening are given from work-hardening, precipitation strengthening and solution strengthening. -- Abstract: Samples of Al-Mg-Mn-Zr-Er alloys have been welded using the method of TIG welding. Microstructures characterization was performed by optical microscopy (OM), energy dispersive X-ray (EDX) and transmission electron microscopy (TEM), respectively. In addition, tensile and hardness test was conducted. The relationship between mechanical properties and microstructure of welded joints is evaluated. Results indicate that the ultimate tensile strength of the joints is 72% of that of the base metal. The base metal consists of a typical rolled structure, and the fusion zone (FZ) is mainly made up of dendrite grains. A characteristic equiaxed zone (EQZ) is obtained at the fusion boundary between the base metal and fusion zone. Fine dispersion of coherent Al 3 Er precipitates was found in the base metal, however, the quantity of these particles dropped significantly in the fusion zone. The hardness test results indicate that the microhardness in the fusion zone is lower than that of the base metal, due to the as-cast structure in this region. Based on the present work, it is concluded that TIG welding is the suitable welding procedure for joining this new type Er-containing aluminum alloy.

Features of mechanical snubbers and the method of selection

International Nuclear Information System (INIS)

Sunakoda, Katsuaki

1978-01-01

In the oil snubbers used in the high radiation environment of nuclear power stations, gas generation from oil and the deterioration of rubber material for sealing occur due to radiation damage, therefore periodical inspection and replacement are required during operation. The mechanical snubbers developed as aseismatic supporters in place of oil snubbers have entered the stage of practical use, and are made by two companies in USA and a company in Japan. Their features as compared with oil snubbers are as follows. The cost and time required for the maintenance were made as small as possible because the increase of the service life of mechanical components can be expected. The temperature dependence of mechanical snubbers is small. The matters demanding attention in the maintenance are the secular change of lubricating oil and the effect of radiation, and the rust prevention of ball screw bearings. These problems are being studied by Power Reactor and Nuclear Fuel Development Corp. for the fast prototype reactor Monju. The structural feature is to convert the thrust movement of equipments and pipings due to thermal expansion and contraction or earthquakes into rotating motion, using ball screws. The features and the construction of SMS type mechanical snubbers, the test and inspection prior to their shipping, the method of selection, and the method of handling them in actual places are explained. (Kako, I.)

Semi-automatic version of the potentiometric titration method for characterization of uranium compounds.

Science.gov (United States)

Cristiano, Bárbara F G; Delgado, José Ubiratan; da Silva, José Wanderley S; de Barros, Pedro D; de Araújo, Radier M S; Dias, Fábio C; Lopes, Ricardo T

2012-09-01

The potentiometric titration method was used for characterization of uranium compounds to be applied in intercomparison programs. The method is applied with traceability assured using a potassium dichromate primary standard. A semi-automatic version was developed to reduce the analysis time and the operator variation. The standard uncertainty in determining the total concentration of uranium was around 0.01%, which is suitable for uranium characterization and compatible with those obtained by manual techniques. Copyright © 2012 Elsevier Ltd. All rights reserved.

Characterization of the active deformation mechanisms in Zirconium alpha alloys, and use of micro-macro transfer models

International Nuclear Information System (INIS)

Francillette, H.; Bacroix, B.; Gasperini, M.; Lebensohn, R.A.

1996-01-01

The aim of this study is to model the evolution of the crystallographic textures of rolled zirconium sheet metals, based on the active deformation mechanisms. Plane compression tests have been carried out on Zr 702 polycrystalline samples, at ambient temperature. Active mechanisms were identified and characterized by the means of local orientation measurements (EBSD: electron BackScattering Diffraction), completed with global texture measurements. Measured orientations are then introduced in Taylor, Sachs and self-coherent type micro-macro models in order to validate these models with respect to mechanism activation and texture evolution. (A.B.)

Calculating solution redox free energies with ab initio quantum mechanical/molecular mechanical minimum free energy path method

International Nuclear Information System (INIS)

Zeng Xiancheng; Hu Hao; Hu Xiangqian; Yang Weitao

2009-01-01

A quantum mechanical/molecular mechanical minimum free energy path (QM/MM-MFEP) method was developed to calculate the redox free energies of large systems in solution with greatly enhanced efficiency for conformation sampling. The QM/MM-MFEP method describes the thermodynamics of a system on the potential of mean force surface of the solute degrees of freedom. The molecular dynamics (MD) sampling is only carried out with the QM subsystem fixed. It thus avoids 'on-the-fly' QM calculations and thus overcomes the high computational cost in the direct QM/MM MD sampling. In the applications to two metal complexes in aqueous solution, the new QM/MM-MFEP method yielded redox free energies in good agreement with those calculated from the direct QM/MM MD method. Two larger biologically important redox molecules, lumichrome and riboflavin, were further investigated to demonstrate the efficiency of the method. The enhanced efficiency and uncompromised accuracy are especially significant for biochemical systems. The QM/MM-MFEP method thus provides an efficient approach to free energy simulation of complex electron transfer reactions.

Mechanism of charity activity

Directory of Open Access Journals (Sweden)

Roman B. Golovkin

2015-12-01

Full Text Available Objective to establish the essential properties of the mechanism of charitable activities and to formulate the concept of quotmechanism of charitable activityquot. Methods the objective of the study is achieved using the complex of methods which are based on the interaction of dialectical and metaphysical analysis the epistemological properties of which allowed to reveal various aspects of the charitable activities mechanism functioning taking into account the principles of comprehensiveness complexity specificity and objectivity of the research. Results the rules are stated of using the term quotmechanismquot to characterize actions of state and law the essence of the charity mechanism is defined the definition of quotthe mechanism of charitable activity quot is formulated. Scientific novelty for the first time at theoretical level in legal science the definition of quotthe mechanism of charitable activityquot is formulated and its essential properties are set. Practical significance the research will contribute to improving the legal regulation in the field of philanthropy as well as to improving the efficiency and quality of charitable activity in the Russian Federation. nbsp

On the potential of computational methods and numerical simulation in ice mechanics

International Nuclear Information System (INIS)

Bergan, Paal G; Cammaert, Gus; Skeie, Geir; Tharigopula, Venkatapathi

2010-01-01

This paper deals with the challenge of developing better methods and tools for analysing interaction between sea ice and structures and, in particular, to be able to calculate ice loads on these structures. Ice loads have traditionally been estimated using empirical data and 'engineering judgment'. However, it is believed that computational mechanics and advanced computer simulations of ice-structure interaction can play an important role in developing safer and more efficient structures, especially for irregular structural configurations. The paper explains the complexity of ice as a material in computational mechanics terms. Some key words here are large displacements and deformations, multi-body contact mechanics, instabilities, multi-phase materials, inelasticity, time dependency and creep, thermal effects, fracture and crushing, and multi-scale effects. The paper points towards the use of advanced methods like ALE formulations, mesh-less methods, particle methods, XFEM, and multi-domain formulations in order to deal with these challenges. Some examples involving numerical simulation of interaction and loads between level sea ice and offshore structures are presented. It is concluded that computational mechanics may prove to become a very useful tool for analysing structures in ice; however, much research is still needed to achieve satisfactory reliability and versatility of these methods.

Application of empirical mode decomposition method for characterization of random vibration signals

Directory of Open Access Journals (Sweden)

Setyamartana Parman

2016-07-01

Full Text Available Characterization of finite measured signals is a great of importance in dynamical modeling and system identification. This paper addresses an approach for characterization of measured random vibration signals where the approach rests on a method called empirical mode decomposition (EMD. The applicability of proposed approach is tested in one numerical and experimental data from a structural system, namely spar platform. The results are three main signal components, comprising: noise embedded in the measured signal as the first component, first intrinsic mode function (IMF called as the wave frequency response (WFR as the second component and second IMF called as the low frequency response (LFR as the third component while the residue is the trend. Band-pass filter (BPF method is taken as benchmark for the results obtained from EMD method.

Standard test methods for characterizing duplex grain sizes

CERN Document Server

American Society for Testing and Materials. Philadelphia

2002-01-01

1.1 These test methods provide simple guidelines for deciding whether a duplex grain size exists. The test methods separate duplex grain sizes into one of two distinct classes, then into specific types within those classes, and provide systems for grain size characterization of each type. 1.2 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this standard to consult appropriate safety and health practices and determine the applicability of regulatory limitations prior to its use.

Tracer Methods for Characterizing Fracture Creation in Engineered Geothermal Systems

Energy Technology Data Exchange (ETDEWEB)

Rose, Peter [Energy & Geoscience Institute at the University of Utah, Salt Lake City, UT (United States); Harris, Joel [Univ. of Utah, Salt Lake City, UT (United States)

2014-05-08

The aim of this proposal is to develop, through novel high-temperature-tracing approaches, three technologies for characterizing fracture creation within Engineered Geothermal Systems (EGS). The objective of a first task is to identify, develop and demonstrate adsorbing tracers for characterizing interwell reservoir-rock surface areas and fracture spacing. The objective of a second task is to develop and demonstrate a methodology for measuring fracture surface areas adjacent to single wells. The objective of a third task is to design, fabricate and test an instrument that makes use of tracers for measuring fluid flow between newly created fractures and wellbores. In one method of deployment, it will be used to identify qualitatively which fractures were activated during a hydraulic stimulation experiment. In a second method of deployment, it will serve to measure quantitatively the rate of fluid flowing from one or more activated fracture during a production test following a hydraulic stimulation.

Application of few-body methods to statistical mechanics

International Nuclear Information System (INIS)

Bolle, D.

1981-01-01

This paper reviews some of the methods to study the thermodynamic properties of a macroscopic system in terms of the scattering processes between the constituent particles in the system. In particular, we discuss the time delay approach to the virial expansion and the use of the arrangement channel quantum mechanics formulation in kinetic theory. (orig.)

Mechanisms and methods for biofouling prevention via aeration

Science.gov (United States)

Dickenson, Natasha; Henoch, Charles; Belden, Jesse

2013-11-01

Biofouling is a major problem for the Navy and marine industries, with significant economic and ecological consequences. Specifically, biofouling on immersed hull surfaces generates increased drag and thus requires increased fuel consumption to maintain speed. Considerable effort has been spent developing techniques to prevent and control biofouling, but with limited success. Control methods that have proven to be effective are costly, time consuming, or negatively affect the environment. Recently, aeration via bubble injection along submerged surfaces has been shown to achieve long-lasting antifouling effects, and is the only effective non-toxic method available. An understanding of the basic mechanisms by which bubble-induced flow impedes biofouling is lacking, but is essential for the design of large-scale systems. We present results from an experimental investigation of several bubble induced flow fields over an inclined plate with simultaneous measurements of the fluid velocity and bubble characteristics using Digital article Image Velocimetry and high speed digital video. Trajectories of representative larval organisms are also resolved and linked with the flow field measurements to determine the mechanisms responsible for biofouling prevention.

Comprehensive genomic characterization of campylobacter genus reveals some underlying mechanisms for its genomic diversification.

Directory of Open Access Journals (Sweden)

Yizhuang Zhou

Full Text Available Campylobacter species.are phenotypically diverse in many aspects including host habitats and pathogenicities, which demands comprehensive characterization of the entire Campylobacter genus to study their underlying genetic diversification. Up to now, 34 Campylobacter strains have been sequenced and published in public databases, providing good opportunity to systemically analyze their genomic diversities. In this study, we first conducted genomic characterization, which includes genome-wide alignments, pan-genome analysis, and phylogenetic identification, to depict the genetic diversity of Campylobacter genus. Afterward, we improved the tetranucleotide usage pattern-based naïve Bayesian classifier to identify the abnormal composition fragments (ACFs, fragments with significantly different tetranucleotide frequency profiles from its genomic tetranucleotide frequency profiles including horizontal gene transfers (HGTs to explore the mechanisms for the genetic diversity of this organism. Finally, we analyzed the HGTs transferred via bacteriophage transductions. To our knowledge, this study is the first to use single nucleotide polymorphism information to construct liable microevolution phylogeny of 21 Campylobacter jejuni strains. Combined with the phylogeny of all the collected Campylobacter species based on genome-wide core gene information, comprehensive phylogenetic inference of all 34 Campylobacter organisms was determined. It was found that C. jejuni harbors a high fraction of ACFs possibly through intraspecies recombination, whereas other Campylobacter members possess numerous ACFs possibly via intragenus recombination. Furthermore, some Campylobacter strains have undergone significant ancient viral integration during their evolution process. The improved method is a powerful tool for bacterial genomic analysis. Moreover, the findings would provide useful information for future research on Campylobacter genus.

A systematic method for characterizing the time-range performance of ground penetrating radar

International Nuclear Information System (INIS)

Strange, A D

2013-01-01

The fundamental performance of ground penetrating radar (GPR) is linked to the ability to measure the signal time-of-flight in order to provide an accurate radar-to-target range estimate. Having knowledge of the actual time range and timing nonlinearities of a trace is therefore important when seeking to make quantitative range estimates. However, very few practical methods have been formally reported in the literature to characterize GPR time-range performance. This paper describes a method to accurately measure the true time range of a GPR to provide a quantitative assessment of the timing system performance and detect and quantify the effects of timing nonlinearity due to timing jitter. The effect of varying the number of samples per trace on the true time range has also been investigated and recommendations on how to minimize the effects of timing errors are described. The approach has been practically applied to characterize the timing performance of two commercial GPR systems. The importance of the method is that it provides the GPR community with a practical method to readily characterize the underlying accuracy of GPR systems. This in turn leads to enhanced target depth estimation as well as facilitating the accuracy of more sophisticated GPR signal processing methods. (paper)

New methodology for mechanical characterization of human superficial facial tissue anisotropic behaviour in vivo.

Science.gov (United States)

Then, C; Stassen, B; Depta, K; Silber, G

2017-07-01

Mechanical characterization of human superficial facial tissue has important applications in biomedical science, computer assisted forensics, graphics, and consumer goods development. Specifically, the latter may include facial hair removal devices. Predictive accuracy of numerical models and their ability to elucidate biomechanically relevant questions depends on the acquisition of experimental data and mechanical tissue behavior representation. Anisotropic viscoelastic behavioral characterization of human facial tissue, deformed in vivo with finite strain, however, is sparse. Employing an experimental-numerical approach, a procedure is presented to evaluate multidirectional tensile properties of superficial tissue layers of the face in vivo. Specifically, in addition to stress relaxation, displacement-controlled multi-step ramp-and-hold protocols were performed to separate elastic from inelastic properties. For numerical representation, an anisotropic hyperelastic material model in conjunction with a time domain linear viscoelasticity formulation with Prony series was employed. Model parameters were inversely derived, employing finite element models, using multi-criteria optimization. The methodology provides insight into mechanical superficial facial tissue properties. Experimental data shows pronounced anisotropy, especially with large strain. The stress relaxation rate does not depend on the loading direction, but is strain-dependent. Preconditioning eliminates equilibrium hysteresis effects and leads to stress-strain repeatability. In the preconditioned state tissue stiffness and hysteresis insensitivity to strain rate in the applied range is evident. The employed material model fits the nonlinear anisotropic elastic results and the viscoelasticity model reasonably reproduces time-dependent results. Inversely deduced maximum anisotropic long-term shear modulus of linear elasticity is G ∞,max aniso =2.43kPa and instantaneous initial shear modulus at an

Rock mass characterization for storage of nuclear waste in granite

International Nuclear Information System (INIS)

Witherspoon, P.A.; Nelson, P.; Doe, T.; Thorpe, R.; Paulsson, B.; Gale, J.; Forster, C.

1979-02-01

The rock mass characterization in granite adjacent to an iron mine at Stripa, Sweden is being carried out by four different methods. The mechanical characterization includes monitoring the responses to thermal loading of jointed rock in situ, and mechanical tests on cores from 25 mm to 1 m in diameter. Geological characterization includes detailed surface mapping, subsurface mapping, and core mapping. Geophysical characterization uses a variety of borehole techniques, with emphasis on sonic methods. The hydrologic characterization is done through injection tests, pump tests, water pressure measurements, and controlled inflow tests to tunnels. Since the data are not yet complete, only tentative conclusions can be drawn regarding the best combinations of techniques for rock-mass characterization. Mapping studies are useful in defining continuity and fracture-system geometry. They do not give aperture, a factor significant in terms of both water flow and the displacements due to heating. Of the geophysical techniques, sonic methods appear most effective in fracture definition; other methods, gamma and neutron particularly, give data on radionuclide and water content and need further analysis with geologic and hydrologic data to determine their significance. Hydrologic work yields primarily aperture data, which with fracture geometry can be used to calculate directional permeabilities. Pressure measurements may provide one means of assessing fracture continuity. Finally, laboratory tests on large cores suggest considerable refinement in testing techniques may be needed before stress-aperture data can be extrapolated from laboratory to field

Quantum mechanical methods for calculation of force constants

International Nuclear Information System (INIS)

Mullally, D.J.

1985-01-01

The focus of this thesis is upon the calculation of force constants; i.e., the second derivatives of the potential energy with respect to nuclear displacements. This information is useful for the calculation of molecular vibrational modes and frequencies. In addition, it may be used for the location and characterization of equilibrium and transition state geometries. The methods presented may also be applied to the calculation of electric polarizabilities and infrared and Raman vibrational intensities. Two approaches to this problem are studied and evaluated: finite difference methods and analytical techniques. The most suitable method depends on the type and level of theory used to calculate the electronic wave function. Double point displacement finite differencing is often required for accurate calculation of the force constant matrix. These calculations require energy and gradient calculations on both sides of the geometry of interest. In order to speed up these calculations, a novel method is presented that uses geometry dependent information about the wavefunction. A detailed derivation for the analytical evaluation of force constants with a complete active space multiconfiguration self consistent field wave function is presented

Algebraic methods in statistical mechanics and quantum field theory

CERN Document Server

Emch, Dr Gérard G

2009-01-01

This systematic algebraic approach concerns problems involving a large number of degrees of freedom. It extends the traditional formalism of quantum mechanics, and it eliminates conceptual and mathematical difficulties common to the development of statistical mechanics and quantum field theory. Further, the approach is linked to research in applied and pure mathematics, offering a reflection of the interplay between formulation of physical motivations and self-contained descriptions of the mathematical methods.The four-part treatment begins with a survey of algebraic approaches to certain phys

Characterization of the mechanical properties of resected porcine organ tissue using optical fiber photoelastic polarimetry.

Science.gov (United States)

Hudnut, Alexa W; Babaei, Behzad; Liu, Sonya; Larson, Brent K; Mumenthaler, Shannon M; Armani, Andrea M

2017-10-01

Characterizing the mechanical behavior of living tissue presents an interesting challenge because the elasticity varies by eight orders of magnitude, from 50Pa to 5GPa. In the present work, a non-destructive optical fiber photoelastic polarimetry system is used to analyze the mechanical properties of resected samples from porcine liver, kidney, and pancreas. Using a quasi-linear viscoelastic fit, the elastic modulus values of the different organ systems are determined. They are in agreement with previous work. In addition, a histological assessment of compressed and uncompressed tissues confirms that the tissue is not damaged during testing.

Tools and methods for experimental in-vivo measurement and biomechanical characterization of an Octopus vulgaris arm.

Science.gov (United States)

Margheri, Laura; Mazzolai, Barbara; Cianchetti, Matteo; Dario, Paolo; Laschi, Cecilia

2009-01-01

This work illustrates new tools and methods for an in vivo and direct, but non-invasive, measurement of an octopus arm mechanical properties. The active elongation (longitudinal stretch) and the pulling force capability are measured on a specimen of Octopus vulgaris in order to quantitatively characterize the parameters describing the arm mechanics, for biomimetic design purposes. The novel approach consists of observing and measuring a living octopus with minimally invasive methods, which allow the animal to move with its complete ability. All tools are conceived in order to create a collaborative interaction with the animal for the acquisition of active measures. The data analysis is executed taking into account the presence of an intrinsic error due to the mobility of the subject and the aquatic environment. Using a system of two synchronized high-speed high-resolution cameras and purpose-made instruments, the maximum elongation of an arm and its rest length (when all muscles fibres are relaxed during propulsion movement) are measured and compared to define the longitudinal stretch, with the impressive average result of 194%. With a similar setup integrated with a force sensor, the pulling force capability is measured as a function of grasp point position along the arm. The measured parameters are used as real specifications for the design of an octopus-like arm with a biomimetic approach.

Computation of Hydration Free Energies Using the Multiple Environment Single System Quantum Mechanical/Molecular Mechanical Method.

Science.gov (United States)

König, Gerhard; Mei, Ye; Pickard, Frank C; Simmonett, Andrew C; Miller, Benjamin T; Herbert, John M; Woodcock, H Lee; Brooks, Bernard R; Shao, Yihan

2016-01-12

A recently developed MESS-E-QM/MM method (multiple-environment single-system quantum mechanical molecular/mechanical calculations with a Roothaan-step extrapolation) is applied to the computation of hydration free energies for the blind SAMPL4 test set and for 12 small molecules. First, free energy simulations are performed with a classical molecular mechanics force field using fixed-geometry solute molecules and explicit TIP3P solvent, and then the non-Boltzmann-Bennett method is employed to compute the QM/MM correction (QM/MM-NBB) to the molecular mechanical hydration free energies. For the SAMPL4 set, MESS-E-QM/MM-NBB corrections to the hydration free energy can be obtained 2 or 3 orders of magnitude faster than fully converged QM/MM-NBB corrections, and, on average, the hydration free energies predicted with MESS-E-QM/MM-NBB fall within 0.10-0.20 kcal/mol of full-converged QM/MM-NBB results. Out of five density functionals (BLYP, B3LYP, PBE0, M06-2X, and ωB97X-D), the BLYP functional is found to be most compatible with the TIP3P solvent model and yields the most accurate hydration free energies against experimental values for solute molecules included in this study.

A New Test Device for Characterization of Mechanical Stress Caused by Packaging Processes

International Nuclear Information System (INIS)

Hirsch, Soeren; Doerner, Steffen; Hauptmann, Peter; Schmidt, Bertram

2006-01-01

This paper reports on a new method for estimation and minimization of mechanical stress on MEMS sensor and actuator structures due to packaging processes based on flip chip technology. For studying mechanical stress a test chip with silicon membranes was fabricated. A network of piezo-resistive solid state resistors created by diffusion was used to measure the surface tension pattern between adjacent membranes. Finite element method simulation was used to calculate the stress profile and to determine the optimum positions for placing the resistive network

Development of method to characterize emissions from spray polyurethane foam insulation

Science.gov (United States)

This presentation updates symposium participants re EPA progress towards development of SPF insulation emissions characterization methods. The presentation highlights evaluation of experiments investigating emissions after application of SPF to substrates in micro chambers and i...

Materials Characterization Center workshop on the leaching mechanisms of nuclear waste forms, December 7-8, 1982, Thousand Oaks, CA. Summary report

International Nuclear Information System (INIS)

Mendel, J.E.; Harker, A.B.

1985-01-01

Each of the six laboratories involved in the 3-yr leaching mechanism program presented a progress report on borosilicate glass studies. Presentations were made on various techniques for characterizing leached surfaces and on in situ characterization of leaching surfaces

Introduction to Analytical Methods for Internal Combustion Engine Cam Mechanisms

CERN Document Server

Williams, J J

2013-01-01

Modern design methods of Automotive Cam Design require the computation of a range of parameters. This book provides a logical sequence of steps for the derivation of the relevant equations from first principles, for the more widely used cam mechanisms. Although originally derived for use in high performance engines, this work is equally applicable to the design of mass produced automotive and other internal combustion engines.   Introduction to Analytical Methods for Internal Combustion Engine Cam Mechanisms provides the equations necessary for the design of cam lift curves with an associated smooth acceleration curve. The equations are derived for the kinematics and kinetics of all the mechanisms considered, together with those for cam curvature and oil entrainment velocity. This permits the cam shape, all loads, and contact stresses to be evaluated, and the relevant tribology to be assessed. The effects of asymmetry on the manufacture of cams for finger follower and offset translating curved followers is ...

Quantum mechanics

CERN Document Server

Ghosh, P K

2014-01-01

Quantum mechanics, designed for advanced undergraduate and graduate students of physics, mathematics and chemistry, provides a concise yet self-contained introduction to the formal framework of quantum mechanics, its application to physical problems and the interpretation of the theory. Starting with a review of some of the necessary mathematics, the basic concepts are carefully developed in the text. After building a general formalism, detailed treatment of the standard material - the harmonic oscillator, the hydrogen atom, angular momentum theory, symmetry transformations, approximation methods, identical particle and many-particle systems, and scattering theory - is presented. The concluding chapter discusses the interpretation of quantum mechanics. Some of the important topics discussed in the book are the rigged Hilbert space, deformation quantization, path integrals, coherent states, geometric phases, decoherene, etc. This book is characterized by clarity and coherence of presentation.

Characterizing heterogeneous cellular responses to perturbations.

Science.gov (United States)

Slack, Michael D; Martinez, Elisabeth D; Wu, Lani F; Altschuler, Steven J

2008-12-09

Cellular populations have been widely observed to respond heterogeneously to perturbation. However, interpreting the observed heterogeneity is an extremely challenging problem because of the complexity of possible cellular phenotypes, the large dimension of potential perturbations, and the lack of methods for separating meaningful biological information from noise. Here, we develop an image-based approach to characterize cellular phenotypes based on patterns of signaling marker colocalization. Heterogeneous cellular populations are characterized as mixtures of phenotypically distinct subpopulations, and responses to perturbations are summarized succinctly as probabilistic redistributions of these mixtures. We apply our method to characterize the heterogeneous responses of cancer cells to a panel of drugs. We find that cells treated with drugs of (dis-)similar mechanism exhibit (dis-)similar patterns of heterogeneity. Despite the observed phenotypic diversity of cells observed within our data, low-complexity models of heterogeneity were sufficient to distinguish most classes of drug mechanism. Our approach offers a computational framework for assessing the complexity of cellular heterogeneity, investigating the degree to which perturbations induce redistributions of a limited, but nontrivial, repertoire of underlying states and revealing functional significance contained within distinct patterns of heterogeneous responses.

Microstructural characterization and formation mechanism of 21° top facets of ZnO-based nanowall structures

Energy Technology Data Exchange (ETDEWEB)

Lee, Ju Ho [Reliability Technology Research Institute, Korea Electronics Technology Institute (KETI), 68 Yatap-dong, Bundang-gu, Seongnam 463-816 (Korea, Republic of); Kim, Dong Chan [OLED Research Team 2, Samsung Mobile Display, San 24 Nonseo-dong, Giheung-gu, Yongin 446-711 (Korea, Republic of); Kim, Sang Yun [Department of Materials Science and Engineering, KAIST and Center for Nanomaterials and Chemical Reactions, IBS, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Choi, SungSoon [Reliability Technology Research Institute, Korea Electronics Technology Institute (KETI), 68 Yatap-dong, Bundang-gu, Seongnam 463-816 (Korea, Republic of); Lee, Kwan-Hun [Electronics and Communication Engineering, Kwangwoon University, 447-1 Wolgye-dong, Nowon-gu, Seoul 139-701 (Korea, Republic of); Lee, Jeong Yong, E-mail: j.y.lee@kaist.ac.kr [Department of Materials Science and Engineering, KAIST and Center for Nanomaterials and Chemical Reactions, IBS, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Koun Cho, Hyung, E-mail: chohk@skku.edu [School of Advanced Materials Science and Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon, Gyeonggi-do 440-746 (Korea, Republic of)

2013-03-01

This study reports the microstructural characterization and formation mechanism of the 21° top facets of ZnO-based nanowall structures. The ZnO-based nanowall structures reported previously by many other research groups have {112"¯0} planes as major planes and top facets with a specific angle in common, irrespective of the growth techniques and growth conditions. These nanowalls were found to exist between two adjacent nanowires with a c-axis preferred orientation, and the atoms at the junction of the nanowalls and nanowires perfectly coincided with each other at an atomic level, without any defects. The top facets of the nanowalls showed periodically stepped surfaces and were identified as {011"¯5} planes, which were perpendicular to the {112"¯0} major planes. On the basis of the microstructural characterization of the synthesized ZnO-based nanowall structures, the formation mechanism and atomic structure model of the 21° top facets of the nanowall structures are proposed.

Analysis of the optimized H type grid spring by a characterization test and the finite element method under the in-grid boundary

International Nuclear Information System (INIS)

Yoon, Kyung Ho; Lee, Kang Hee; Kang, Heung Seok; Song, Kee Nam

2006-01-01

Characterization tests (load vs. displacement curve) are conducted for the springs of Zirconium alloy spacer grids for an advanced LWR fuel assembly. Twofold testing is employed: strap-based and assembly-based tests. The assembly-based test satisfies the in situ boundary conditions of the spring within the grid assembly. The aim of the characterization test via the aforementioned two methods is to establish an appropriate assembly-based test method that fulfills the actual boundary conditions. A characterization test under the spacer grid assembly boundary condition is also conducted to investigate the actual behavior of the spring in the core. The stiffness of the characteristic curve is smaller than that of the strap-wised boundary condition. This phenomenon may cause the strap slit condition. A spacer grid consists of horizontal and vertical straps. The strap slit positions are differentiated from each other. They affords examination of the variation of the external load distribution in the grid spring. Localized regions of high stress and their values are analyzed, as they may be affected by the spring shape. Through a comparison of the results of the test and FE analysis, it is concluded that the present assembly-based analysis model and procedure are reasonably well conducted and can be used for spring characterization in the core. Guidelines for improving the mechanical integrity of the spring are also discussed

Elevator mechanism and method for scintillation detectors

International Nuclear Information System (INIS)

Frank, E.

1975-01-01

An elevator mechanism and method for raising and lowering radioactive samples through a shielded vertical counting chamber in a benchtop scintillation detector is described. The elevator mechanism adds little or nothing to the height of the detector by using an elongated flexible member such as a metal tape secured to the bottom of the elevator platform and extending downwardly through the counting chamber and its bottom shielding, where the tape is bent laterally for connection to a drive means. In the particular embodiment illustrated, the tape is bent laterally below the bottom shielding for the counting chamber, and then upwardly along or through one side of the shielding to a reel at the top of the shielding. The tape is wound onto the reel, and the reel is driven by a reversible motor which winds and unwinds the tape on the reel to raise and lower the elevator platform

Characterizing the mechanism of thiazolidinedione-induced hepatotoxicity: An in vitro model in mitochondria

International Nuclear Information System (INIS)

Hu, Dan; Wu, Chun-qi; Li, Ze-jun; Liu, Yue; Fan, Xing; Wang, Quan-jun; Ding, Ri-gao

2015-01-01

Objective: To characterize the mechanism of action of thiazolidinedione (TZD)-induced liver mitochondrial toxicity caused by troglitazone, rosiglitazone, and pioglitazone in HepaRG cells. Methods: Human hepatoma cells (HepaRG) were treated with troglitazone, rosiglitazone, or pioglitazone (12.5, 25, and 50 μM) for 48 h. The Seahorse Biosciences XF24 Flux Analyzer was used to measure mitochondrial oxygen consumption. The effect of TZDs on reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) were detected by flow cytometry. The mitochondrial ultrastructure of HepaRG cells was observed under a transmission electrical microscope (TEM). mtDNA content was evaluated by real-time PCR, and ATP content and mitochondrial respiratory chain (MRC) complex I, II, III, IV activity were measured via chemiluminescence. Results were considered statistically significant at p < 0.05. Results: Among the three drugs, troglitazone exhibited the highest potency, followed by rosiglitazone, and then pioglitazone. The TZDs caused varying degrees of mitochondrial respiratory function disorders including decreases in oxygen consumption, MRC activity, and ATP level, and an elevation in ROS level. TZD treatment resulted in mtDNA content decline, reduction in MMP, and alterations of mitochondrial structure. Conclusion: All investigated TZDs show a certain degree of mitochondrial toxicity, with troglitazone exhibiting the highest potency. The underlying mechanism of TZD-induced hepatotoxicity may be associated with alterations in mitochondrial respiratory function disorders, oxidative stress, and changes in membrane permeability. These parameters may be used early in drug development to further optimize risk:benefit profiles. - Highlights: • We compared three TZD mitochondrial toxicity characteristics in HepaRG cells. • TZD induced respiratory disorders and mitochondrial structural damage. • Mitochondrial toxicity evaluation presents guidance value for hepatotoxicity

Characterizing the mechanism of thiazolidinedione-induced hepatotoxicity: An in vitro model in mitochondria

Energy Technology Data Exchange (ETDEWEB)

Hu, Dan; Wu, Chun-qi [State Key Laboratory of Toxicology and Medical Countermeasures, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, 27 Taiping Road, Beijing 100850 (China); Li, Ze-jun [State Key Laboratory of Toxicology and Medical Countermeasures, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, 27 Taiping Road, Beijing 100850 (China); Guang Dong Pharmaceutical University, Guangzhou 510006 (China); Liu, Yue; Fan, Xing [State Key Laboratory of Toxicology and Medical Countermeasures, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, 27 Taiping Road, Beijing 100850 (China); Wang, Quan-jun, E-mail: wangquanjunbeijing@163.com [State Key Laboratory of Toxicology and Medical Countermeasures, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, 27 Taiping Road, Beijing 100850 (China); Ding, Ri-gao, E-mail: dingrigao@nic.bmi.ac.cn [State Key Laboratory of Toxicology and Medical Countermeasures, Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, 27 Taiping Road, Beijing 100850 (China)

2015-04-15

Objective: To characterize the mechanism of action of thiazolidinedione (TZD)-induced liver mitochondrial toxicity caused by troglitazone, rosiglitazone, and pioglitazone in HepaRG cells. Methods: Human hepatoma cells (HepaRG) were treated with troglitazone, rosiglitazone, or pioglitazone (12.5, 25, and 50 μM) for 48 h. The Seahorse Biosciences XF24 Flux Analyzer was used to measure mitochondrial oxygen consumption. The effect of TZDs on reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) were detected by flow cytometry. The mitochondrial ultrastructure of HepaRG cells was observed under a transmission electrical microscope (TEM). mtDNA content was evaluated by real-time PCR, and ATP content and mitochondrial respiratory chain (MRC) complex I, II, III, IV activity were measured via chemiluminescence. Results were considered statistically significant at p < 0.05. Results: Among the three drugs, troglitazone exhibited the highest potency, followed by rosiglitazone, and then pioglitazone. The TZDs caused varying degrees of mitochondrial respiratory function disorders including decreases in oxygen consumption, MRC activity, and ATP level, and an elevation in ROS level. TZD treatment resulted in mtDNA content decline, reduction in MMP, and alterations of mitochondrial structure. Conclusion: All investigated TZDs show a certain degree of mitochondrial toxicity, with troglitazone exhibiting the highest potency. The underlying mechanism of TZD-induced hepatotoxicity may be associated with alterations in mitochondrial respiratory function disorders, oxidative stress, and changes in membrane permeability. These parameters may be used early in drug development to further optimize risk:benefit profiles. - Highlights: • We compared three TZD mitochondrial toxicity characteristics in HepaRG cells. • TZD induced respiratory disorders and mitochondrial structural damage. • Mitochondrial toxicity evaluation presents guidance value for hepatotoxicity.

Multiscale simulations in face-centered cubic metals: A method coupling quantum mechanics and molecular mechanics

International Nuclear Information System (INIS)

Yu Xiao-Xiang; Wang Chong-Yu

2013-01-01

An effective multiscale simulation which concurrently couples the quantum-mechanical and molecular-mechanical calculations based on the position continuity of atoms is presented. By an iterative procedure, the structure of the dislocation core in face-centered cubic metal is obtained by first-principles calculation and the long-range stress is released by molecular dynamics relaxation. Compared to earlier multiscale methods, the present work couples the long-range strain to the local displacements of the dislocation core in a simpler way with the same accuracy. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Evaluation of mechanical properties and microstructural characterization of consolidated Cobalt-Chromium-Molybdenum obtained by selective laser melting and precision casting

International Nuclear Information System (INIS)

Mergulhão, Marcello Vertamatti

2017-01-01

The objective of this work was to study the mechanical properties and microstructural characterization of specimens of the Co-Cr-Mo alloy obtained by additive manufacturing -selective laser melting (SLM) and precision casting aiming at the manufacture of dental prostheses. The following steps were carried out on Co-Cr-Mo gas-atomized powders: 1) investigation of the physical, chemical and thermal properties of atomized powders in different grain sizes (denominated: D1 <15 μm, D2 20-50 μm and D3 > 75 μm); 2) the consolidation of standard specimens via consolidation techniques; 3) characterization of consolidated by analysis of: cytotoxicity, porosity, X ray diffraction and dilatometry; 4) mechanical characterization of tensile, 3 point bending, hardness (macro and micro Vickers) tests and microstructural characterization (optical and scanning electron microscopy). In general, the results observed were: the grain size D2 (20-50 μm) is the one that best fits in the analysis of packaging, for the consolidation by SLM; the biocompatibility of the samples obtained a positive result for both processing techniques; the mechanical evaluation of the specimens shows that the SLM technique provides superior mechanical properties (yield stress, rupture stress, maximum stress, elongation and hardness), compared to those obtained by the precision casting technique; the microstructure obtained by the SLM process results in an ultrafine grains with high chemical homogeneity, differentiated by the gross dendritic microstructure in the casting process. In this way, the development of the present study evidenced superior quality in manufacturing customized dental components (copings) by SLM technique compared to precision casting. (author)

DOE assay methods used for characterization of contact-handled transuranic waste

Energy Technology Data Exchange (ETDEWEB)

Schultz, F.J. (Oak Ridge National Lab., TN (United States)); Caldwell, J.T. (Pajarito Scientific Corp., Los Alamos, NM (United States))

1991-08-01

US Department of Energy methods used for characterization of contact-handled transuranic (CH-TRU) waste prior to shipment to the Waste Isolation Pilot Plant (WIPP) are described and listed by contractor site. The methods described are part of the certification process. All CH-TRU waste must be assayed for determination of fissile material content and decay heat values prior to shipment and prior to storage on-site. Both nondestructive assay (NDA) and destructive assay methods are discussed, and new NDA developments such as passive-action neutron (PAN) crate counter improvements and neutron imaging are detailed. Specifically addressed are assay method physics; applicability to CH-TRU wastes; calibration standards and implementation; operator training requirements and practices; assay procedures; assay precision, bias, and limit of detection; and assay limitation. While PAN is a new technique and does not yet have established American Society for Testing and Materials. American National Standards Institute, or Nuclear Regulatory Commission guidelines or methods describing proper calibration procedures, equipment setup, etc., comparisons of PAN data with the more established assay methods (e.g., segmented gamma scanning) have demonstrated its reliability and accuracy. Assay methods employed by DOE have been shown to reliable and accurate in determining fissile, radionuclide, alpha-curie content, and decay heat values of CH-TRU wastes. These parameters are therefore used to characterize packaged waste for use in certification programs such as that used in shipment of CH-TRU waste to the WIPP. 36 refs., 10 figs., 7 tabs.

DOE assay methods used for characterization of contact-handled transuranic waste

International Nuclear Information System (INIS)

Schultz, F.J.; Caldwell, J.T.

1991-08-01

US Department of Energy methods used for characterization of contact-handled transuranic (CH-TRU) waste prior to shipment to the Waste Isolation Pilot Plant (WIPP) are described and listed by contractor site. The methods described are part of the certification process. All CH-TRU waste must be assayed for determination of fissile material content and decay heat values prior to shipment and prior to storage on-site. Both nondestructive assay (NDA) and destructive assay methods are discussed, and new NDA developments such as passive-action neutron (PAN) crate counter improvements and neutron imaging are detailed. Specifically addressed are assay method physics; applicability to CH-TRU wastes; calibration standards and implementation; operator training requirements and practices; assay procedures; assay precision, bias, and limit of detection; and assay limitation. While PAN is a new technique and does not yet have established American Society for Testing and Materials. American National Standards Institute, or Nuclear Regulatory Commission guidelines or methods describing proper calibration procedures, equipment setup, etc., comparisons of PAN data with the more established assay methods (e.g., segmented gamma scanning) have demonstrated its reliability and accuracy. Assay methods employed by DOE have been shown to reliable and accurate in determining fissile, radionuclide, alpha-curie content, and decay heat values of CH-TRU wastes. These parameters are therefore used to characterize packaged waste for use in certification programs such as that used in shipment of CH-TRU waste to the WIPP. 36 refs., 10 figs., 7 tabs

Application of artificial intelligence methods for prediction of steel mechanical properties

Directory of Open Access Journals (Sweden)

Z. Jančíková

2008-10-01

Full Text Available The target of the contribution is to outline possibilities of applying artificial neural networks for the prediction of mechanical steel properties after heat treatment and to judge their perspective use in this field. The achieved models enable the prediction of final mechanical material properties on the basis of decisive parameters influencing these properties. By applying artificial intelligence methods in combination with mathematic-physical analysis methods it will be possible to create facilities for designing a system of the continuous rationalization of existing and also newly developing industrial technologies.

Methods for Characterization of the Diesel Combustion and Emission Formation Processes

Energy Technology Data Exchange (ETDEWEB)

Lindstroem, Mikael

2011-07-01

In this thesis various aspects of the diesel engine fuel injection, combustion and emission formation processes have been evaluated. Several types of evaluation tools and methods have been applied. Fuel spray momentum was used to characterize injection rate and hole-to-hole variations in fuel injectors. Using both instantaneous fuel impulse rates and instantaneous mass flow measurements, spray velocity and nozzle flow parameters were evaluated. Several other hole-to-hole resolved injector characterization methods were used to characterize a set of fuel injectors subjected to long term testing. Fuel injector nozzle hole-to-hole variations were found to have a large influence on engine efficiency and emissions. The degree of hole-to-hole variations for an injector has been shown to correlate well with the performance deterioration of that injector. The formation and atomization of fuel sprays, ignition onset and the development of diffusion flames were studied using an optical engine. Flame temperature evaluations have been made using two different methods. NO-formation depends strongly on flame temperature. By applying a NO-formation evaluation method based on both heat release rate and flame and gas temperature it was possible to achieve a reasonable degree of correlation with measured exhaust emissions for very varying operating conditions. The prediction capability of the NO-formation evaluation method was utilized to evaluate spatially and temporally resolved NO-formation from flame temperature distributions. This made it possible to pinpoint areas with a high degree of NO-formation. It was found that small hot zones in the flames can be responsible for a large part of the total amount of NO that is produced, especially in combustion cases where no EGR is used to lower the flame temperature. By applying optical diagnostics methods the combustion and emission formation phenomena encountered during production engine transients were evaluated. The transient

Comparison of optical methods for surface roughness characterization

DEFF Research Database (Denmark)

Feidenhans'l, Nikolaj Agentoft; Hansen, Poul Erik; Pilny, Lukas

2015-01-01

We report a study of the correlation between three optical methods for characterizing surface roughness: a laboratory scatterometer measuring the bi-directional reflection distribution function (BRDF instrument), a simple commercial scatterometer (rBRDF instrument), and a confocal optical profiler....... For each instrument, the effective range of spatial surface wavelengths is determined, and the common bandwidth used when comparing the evaluated roughness parameters. The compared roughness parameters are: the root-mean-square (RMS) profile deviation (Rq), the RMS profile slope (Rdq), and the variance...... of the scattering angle distribution (Aq). The twenty-two investigated samples were manufactured with several methods in order to obtain a suitable diversity of roughness patterns.Our study shows a one-to-one correlation of both the Rq and the Rdq roughness values when obtained with the BRDF and the confocal...

TRANSFER PRICES: MECHANISMS, METHODS AND INTERNATIONAL APPROACHES

Directory of Open Access Journals (Sweden)

Pop Cosmina

2008-05-01

Full Text Available Transfer prices are considered the prices paid for the goods or services in a cross-border transaction between affiliates companies, often significant reduced or increased in order to avoid the higher imposing rates from one jurisdiction. Presently, over 60% of cross-border transfers are represented by intra-group transfers. The paper presents the variety of methods and mechanisms used by the companies to transfer the funds from one tax jurisdiction to another in order to avoid over taxation.

Synthesis and characterization of cobalt sulfide nanoparticles by sonochemical method

Science.gov (United States)

Muradov, Mustafa B.; Balayeva, Ofeliya O.; Azizov, Abdulsaid A.; Maharramov, Abel M.; Qahramanli, Lala R.; Eyvazova, Goncha M.; Aghamaliyev, Zohrab A.

2018-03-01

Convenient and environmentally friendly synthesis of Co9S8/PVA, CoxSy/EG and CoxSy/3-MPA nanocomposites were carried out in the presence of ultrasonic irradiation by the liquid phase synthesis of the sonochemical method. For the synthesis, cobalt acetate tetrahydrate [Co(CH3COO)2·4H2O] and sodium sulfide (Na2S·9H2O) were used as a cobalt and sulfur precursor, respectively. Polyvinyl alcohol (PVA), ethylene glycol (EG) and 3-mercaptopropionic acid (3-MPA) were used as a capping agent and surfactant. The structural, optical properties and morphology of nanocomposites were characterized using X-ray diffractometer (XRD), Ultraviolet/Visible Spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The optical band gap of Co9S8/PVA is 1.81 eV and for CoxSy/EG is 2.42 eV, where the direct band gap of bulk cobalt sulfide is (0.78-0.9 eV). The wide band gap indicates that synthesised nanocomposites can be used in the fabrication of optical and photonic devices. The growth mechanisms of the Co9S8, CoS2 and Co3S4 nanoparticles were discussed by the reactions. The effects of sonication time and annealing temperature on the properties of the nanoparticles have been studied in detail.

Integrated automated nanomanipulation and real-time cellular surface imaging for mechanical properties characterization

Science.gov (United States)

Eslami, Sohrab; Zareian, Ramin; Jalili, Nader

2012-10-01

Surface microscopy of individual biological cells is essential for determining the patterns of cell migration to study the tumor formation or metastasis. This paper presents a correlated and effective theoretical and experimental technique to automatically address the biophysical and mechanical properties and acquire live images of biological cells which are of interest in studying cancer. In the theoretical part, a distributed-parameters model as the comprehensive representation of the microcantilever is presented along with a model of the contact force as a function of the indentation depth and mechanical properties of the biological sample. Analysis of the transfer function of the whole system in the frequency domain is carried out to characterize the stiffness and damping coefficients of the sample. In the experimental section, unlike the conventional atomic force microscope techniques basically using the laser for determining the deflection of microcantilever's tip, a piezoresistive microcantilever serving as a force sensor is implemented to produce the appropriate voltage and measure the deflection of the microcantilever. A micromanipulator robotic system is integrated with the MATLAB® and programmed in such a way to automatically control the microcantilever mounted on the tip of the micromanipulator to achieve the topography of biological samples including the human corneal cells. For this purpose, the human primary corneal fibroblasts are extracted and adhered on a sterilized culture dish and prepared to attain their topographical image. The proposed methodology herein allows an approach to obtain 2D quality images of cells being comparatively cost effective and extendable to obtain 3D images of individual cells. The characterized mechanical properties of the human corneal cell are furthermore established by comparing and validating the phase shift of the theoretical and experimental results of the frequency response.

Combined quantum mechanical and molecular mechanical method for metal-organic frameworks: proton topologies of NU-1000.

Science.gov (United States)

Wu, Xin-Ping; Gagliardi, Laura; Truhlar, Donald G

2018-01-17

Metal-organic frameworks (MOFs) are materials with applications in catalysis, gas separations, and storage. Quantum mechanical (QM) calculations can provide valuable guidance to understand and predict their properties. In order to make the calculations faster, rather than modeling these materials as periodic (infinite) systems, it is useful to construct finite models (called cluster models) and use subsystem methods such as fragment methods or combined quantum mechanical and molecular mechanical (QM/MM) methods. Here we employ a QM/MM methodology to study one particular MOF that has been of widespread interest because of its wide pores and good solvent and thermal stability, namely NU-1000, which contains hexanuclear zirconium nodes and 1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy 4- ) linkers. A modified version of the Bristow-Tiana-Walsh transferable force field has been developed to allow QM/MM calculations on NU-1000; we call the new parametrization the NU1T force field. We consider isomeric structures corresponding to various proton topologies of the [Zr 6 (μ 3 -O) 8 O 8 H 16 ] 8+ node of NU-1000, and we compute their relative energies using a QM/MM scheme designed for the present kind of problem. We compared the results to full quantum mechanical (QM) energy calculations and found that the QM/MM models can reproduce the full QM relative energetics (which span a range of 334 kJ mol -1 ) with a mean unsigned deviation (MUD) of only 2 kJ mol -1 . Furthermore, we found that the structures optimized by QM/MM are nearly identical to their full QM optimized counterparts.

Characterization of mechanical behavior of a porcine pulmonary artery strip using a randomized uniaxial stretch and stretch-rate protocol

Directory of Open Access Journals (Sweden)

Criscione John C

2008-01-01

Full Text Available Abstract Background Much of the experimental work in soft tissue mechanics has been focused on fitting approximate relations for specific tissue types from aggregate data on multiple samples of the tissue. Such relations are needed for modeling applications and have reasonable predictability – especially given the natural variance in specimens. There is, however, much theoretical and experimental work to be done in determining constitutive behaviors for particular specimens and tissues. In so doing, it may be possible to exploit the natural variation in tissue ultrastructure – so to relate ultrastructure composition to tissue behavior. Thus, this study focuses on an experimental method for determining constitutive behaviors and illustrates the method with analysis of a porcine pulmonary artery strip. The method characterizes the elastic part of the response (implicitly in terms of stretch and the inelastic part in terms of short term stretch history (i.e., stretch-rate Ht2, longer term stretch history Ht1, and time since the start of testing T. Methods A uniaxial testing protocol with a random stretch and random stretch-rate was developed. The average stress at a particular stretch was chosen as the hyperelastic stress response, and deviation from the mean at this particular stretch is chosen as the inelastic deviation. Multivariable Linear Regression Analysis (MLRA was utilized to verify if Ht2, Ht1, and T are important factors for characterizing the inelastic deviation. For acquiring Ht2 and Ht1, an integral function type of stretch history was employed with time constants chosen from the relaxation spectrum of an identical size strip from the same tissue with the same orientation. Finally, statistical models that characterize the inelasticity were developed at various, nominal values of stretch, and their predictive capability was examined. Results Inelastic deviation from hyperelasticity was high (31% for low stretch and declined

Geophysical methods for fracture characterization in and around potential sites for nuclear waste disposal

International Nuclear Information System (INIS)

Majer, E.L.; Lee, K.H.; Morrison, H.F.

1992-08-01

Historically, geophysical methods have been used extensively to successfully explore the subsurface for petroleum, gas, mineral, and geothermal resources. Their application, however, for site characterization, and monitoring the performance of near surface waste sites or repositories has been somewhat limited. Presented here is an overview of the geophysical methods that could contribute to defining the subsurface heterogeneity and extrapolating point measurements at the surface and in boreholes to volumetric descriptions in a fractured rock. In addition to site characterization a significant application of geophysical methods may be in performance assessment and in monitoring the repository to determine if the performance is as expected

DESIGN OPTIMIZATION METHOD USED IN MECHANICAL ENGINEERING

Directory of Open Access Journals (Sweden)

SCURTU Iacob Liviu

2016-11-01

Full Text Available This paper presents an optimization study in mechanical engineering. First part of the research describe the structural optimization method used, followed by the presentation of several optimization studies conducted in recent years. The second part of the paper presents the CAD modelling of an agricultural plough component. The beam of the plough is analysed using finite element method. The plough component is meshed in solid elements, and the load case which mimics the working conditions of agricultural equipment of this are created. The model is prepared to find the optimal structural design, after the FEA study of the model is done. The mass reduction of part is the criterion applied for this optimization study. The end of this research presents the final results and the model optimized shape.

Ultrasound Imaging Techniques for Spatiotemporal Characterization of Composition, Microstructure, and Mechanical Properties in Tissue Engineering.

Science.gov (United States)

Deng, Cheri X; Hong, Xiaowei; Stegemann, Jan P

2016-08-01

Ultrasound techniques are increasingly being used to quantitatively characterize both native and engineered tissues. This review provides an overview and selected examples of the main techniques used in these applications. Grayscale imaging has been used to characterize extracellular matrix deposition, and quantitative ultrasound imaging based on the integrated backscatter coefficient has been applied to estimating cell concentrations and matrix morphology in tissue engineering. Spectral analysis has been employed to characterize the concentration and spatial distribution of mineral particles in a construct, as well as to monitor mineral deposition by cells over time. Ultrasound techniques have also been used to measure the mechanical properties of native and engineered tissues. Conventional ultrasound elasticity imaging and acoustic radiation force imaging have been applied to detect regions of altered stiffness within tissues. Sonorheometry and monitoring of steady-state excitation and recovery have been used to characterize viscoelastic properties of tissue using a single transducer to both deform and image the sample. Dual-mode ultrasound elastography uses separate ultrasound transducers to produce a more potent deformation force to microscale characterization of viscoelasticity of hydrogel constructs. These ultrasound-based techniques have high potential to impact the field of tissue engineering as they are further developed and their range of applications expands.

Characterization investigations during mechanical alloying and sintering of Ni-W solid solution alloys dispersed with WC and Y2O3 particles

International Nuclear Information System (INIS)

Genc, Aziz; Luetfi Ovecoglu, M.

2010-01-01

Research highlights: → Characterization investigations on the Ni-W solid solution alloys fabricated via mechanical alloying and the evolution of the properties of the powders with increasing MA durations. → Reinforcement of the selected Ni-W powders with WC and Y 2 O 3 particles and further MA together for 12 h. → There is no reported literature on the development and characterization of Ni-W solid solution alloys matrix composites fabricated via MA. → Sintering of the developed composites and the characterization investigations of the sintered samples. → Identification of new 'pomegranate-like' structures in the bulk of the samples. - Abstract: Blended elemental Ni-30 wt.% W powders were mechanically alloyed (MA'd) for 1 h, 3 h, 6 h, 12 h, 24 h, 36 h and 48 h in a Spex mixer/mill at room temperature in order to investigate the effects of MA duration on the solubility of W in Ni and the grain size, hardness and particle size. Microstructural and phase characterizations of the MA'd powders were carried out using X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). On the basis of achieved saturation on the solid solubility, hardness and particle size, the Ni-30 wt.% W powders MA'd for 48 h were chosen as the matrix which was reinforced with different amounts of WC and/or with 1 wt.% Y 2 O 3 particles. The reinforced powders were further MA'd for 12 h. The MA'd powders were sintered at 1300 o C for 1 h under Ar and H 2 gas flowing conditions. Microstructural characterizations of the sintered samples were conducted via XRD and SEM. Sintered densities were measured by using the Archimedes' method. Vickers microhardness tests were performed on both MA'd powders and the sintered samples. Sliding wear experiments were done in order to investigate wear behaviors of the sintered samples.

Detecting method for crude oil price fluctuation mechanism under different periodic time series

International Nuclear Information System (INIS)

Gao, Xiangyun; Fang, Wei; An, Feng; Wang, Yue

2017-01-01

Highlights: • We proposed the concept of autoregressive modes to indicate the fluctuation patterns. • We constructed transmission networks for studying the fluctuation mechanism. • There are different fluctuation mechanism under different periodic time series. • Only a few types of autoregressive modes control the fluctuations in crude oil price. • There are cluster effects during the fluctuation mechanism of autoregressive modes. - Abstract: Current existing literatures can characterize the long-term fluctuation of crude oil price time series, however, it is difficult to detect the fluctuation mechanism specifically under short term. Because each fluctuation pattern for one short period contained in a long-term crude oil price time series have dynamic characteristics of diversity; in other words, there exhibit various fluctuation patterns in different short periods and transmit to each other, which reflects the reputedly complicate and chaotic oil market. Thus, we proposed an incorporated method to detect the fluctuation mechanism, which is the evolution of the different fluctuation patterns over time from the complex network perspective. We divided crude oil price time series into segments using sliding time windows, and defined autoregressive modes based on regression models to indicate the fluctuation patterns of each segment. Hence, the transmissions between different types of autoregressive modes over time form a transmission network that contains rich dynamic information. We then capture transmission characteristics of autoregressive modes under different periodic time series through the structure features of the transmission networks. The results indicate that there are various autoregressive modes with significantly different statistical characteristics under different periodic time series. However, only a few types of autoregressive modes and transmission patterns play a major role in the fluctuation mechanism of the crude oil price, and these

Preparation and characterization of poly(methyl methacrylate)-clay nanocomposites via melt intercalation: Effect of organoclay on thermal, mechanical and flammability properties

Energy Technology Data Exchange (ETDEWEB)

Unnikrishnan, Lakshmi; Mohanty, Smita [Laboratory for Advanced Research in Polymeric Materials (LARPM), Central Institute of Plastics Engineering and Technology, Bhubaneswar 751024 (India); Nayak, Sanjay K., E-mail: drsknayak@gmail.com [Laboratory for Advanced Research in Polymeric Materials (LARPM), Central Institute of Plastics Engineering and Technology, Bhubaneswar 751024 (India); Ali, Anwar [Laboratory for Advanced Research in Polymeric Materials (LARPM), Central Institute of Plastics Engineering and Technology, Bhubaneswar 751024 (India)

2011-05-15

Research highlights: {yields} The present work deals with preparation and characterization of poly(methyl methacrylate) nanocomposites via melt intercalation technique. {yields} The effect of various modified nanoclays on the properties of base matrix has been investigated. {yields} It was observed that compatibilization using maleic anhydride improved the performance characteristics of PMMA/layered silicate nanocomposites. - Abstract: The PMMA nanocomposites were prepared by melt processing method. The influence of organoclay loading on extent of intercalation, thermal, mechanical and flammability properties of poly(methyl methacrylate) (PMMA)-clay nanocomposites were studied. Three different organoclay modifiers with varying hydrophobicity (single tallow vs. ditallow) were investigated. The nanocomposites were characterized by using wide angle X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), and tensile tests. The intercalation of polymer chain within the silicate galleries was confirmed by WAXD and TEM. Mechanical properties such as tensile modulus (E), tensile strength, percentage elongation at break and impact strength were determined for nanocomposites at various clay loadings. Overall thermal stability of nanocomposites increased by 16-17 deg. C. The enhancement in T{sub g} of nanocomposite is merely by 2-4 deg. C. The incorporation of maleic anhydride as compatibilizer further enhanced all the properties indicating improved interface between PMMA and clay. The flammability characteristics were studied by determining the rate of burning and LOI.

Preparation and characterization of poly(methyl methacrylate)-clay nanocomposites via melt intercalation: Effect of organoclay on thermal, mechanical and flammability properties

International Nuclear Information System (INIS)

Unnikrishnan, Lakshmi; Mohanty, Smita; Nayak, Sanjay K.; Ali, Anwar

2011-01-01

Research highlights: → The present work deals with preparation and characterization of poly(methyl methacrylate) nanocomposites via melt intercalation technique. → The effect of various modified nanoclays on the properties of base matrix has been investigated. → It was observed that compatibilization using maleic anhydride improved the performance characteristics of PMMA/layered silicate nanocomposites. - Abstract: The PMMA nanocomposites were prepared by melt processing method. The influence of organoclay loading on extent of intercalation, thermal, mechanical and flammability properties of poly(methyl methacrylate) (PMMA)-clay nanocomposites were studied. Three different organoclay modifiers with varying hydrophobicity (single tallow vs. ditallow) were investigated. The nanocomposites were characterized by using wide angle X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), and tensile tests. The intercalation of polymer chain within the silicate galleries was confirmed by WAXD and TEM. Mechanical properties such as tensile modulus (E), tensile strength, percentage elongation at break and impact strength were determined for nanocomposites at various clay loadings. Overall thermal stability of nanocomposites increased by 16-17 deg. C. The enhancement in T g of nanocomposite is merely by 2-4 deg. C. The incorporation of maleic anhydride as compatibilizer further enhanced all the properties indicating improved interface between PMMA and clay. The flammability characteristics were studied by determining the rate of burning and LOI.

A two-step method for rapid characterization of electroosmotic flows in capillary electrophoresis.

Science.gov (United States)

Zhang, Wenjing; He, Muyi; Yuan, Tao; Xu, Wei

2017-12-01

The measurement of electroosmotic flow (EOF) is important in a capillary electrophoresis (CE) experiment in terms of performance optimization and stability improvement. Although several methods exist, there are demanding needs to accurately characterize ultra-low electroosmotic flow rates (EOF rates), such as in coated capillaries used in protein separations. In this work, a new method, called the two-step method, was developed to accurately and rapidly measure EOF rates in a capillary, especially for measuring the ultra-low EOF rates in coated capillaries. In this two-step method, the EOF rates were calculated by measuring the migration time difference of a neutral marker in two consecutive experiments, in which a pressure driven was introduced to accelerate the migration and the DC voltage was reversed to switch the EOF direction. Uncoated capillaries were first characterized by both this two-step method and a conventional method to confirm the validity of this new method. Then this new method was applied in the study of coated capillaries. Results show that this new method is not only fast in speed, but also better in accuracy. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Experimental Hydro-Mechanical Characterization of Full Load Pressure Surge in Francis Turbines

Science.gov (United States)

Müller, A.; Favrel, A.; Landry, C.; Yamamoto, K.; Avellan, F.

2017-04-01

Full load pressure surge limits the operating range of hydro-electric generating units by causing significant power output swings and by compromising the safety of the plant. It appears during the off-design operation of hydraulic machines, which is increasingly required to regulate the broad integration of volatile renewable energy sources into the existing power network. The underlying causes and governing physical mechanisms of this instability were investigated in the frame of a large European research project and this paper documents the main findings from two experimental campaigns on a reduced scale model of a Francis turbine. The multi-phase flow in the draft tube is characterized by Particle Image Velocimetry, Laser Doppler Velocimetry and high-speed visualizations, along with synchronized measurements of the relevant hydro-mechanical quantities. The final result is a comprehensive overview of how the unsteady draft tube flow and the mechanical torque on the runner shaft behave during one mean period of the pressure oscillation, thus defining the unstable fluid-structure interaction responsible for the power swings. A discussion of the root cause is initiated, based on the state of the art. Finally, the latest results will enable a validation of recent RANS flow simulations used for determining the key parameters of hydro-acoustic stability models.

Automated air-void system characterization of hardened concrete: Helping computers to count air-voids like people count air-voids---Methods for flatbed scanner calibration

Science.gov (United States)

Peterson, Karl

Since the discovery in the late 1930s that air entrainment can improve the durability of concrete, it has been important for people to know the quantity, spacial distribution, and size distribution of the air-voids in their concrete mixes in order to ensure a durable final product. The task of air-void system characterization has fallen on the microscopist, who, according to a standard test method laid forth by the American Society of Testing and Materials, must meticulously count or measure about a thousand air-voids per sample as exposed on a cut and polished cross-section of concrete. The equipment used to perform this task has traditionally included a stereomicroscope, a mechanical stage, and a tally counter. Over the past 30 years, with the availability of computers and digital imaging, automated methods have been introduced to perform the same task, but using the same basic equipment. The method described here replaces the microscope and mechanical stage with an ordinary flatbed desktop scanner, and replaces the microscopist and tally counter with a personal computer; two pieces of equipment much more readily available than a microscope with a mechanical stage, and certainly easier to find than a person willing to sit for extended periods of time counting air-voids. Most laboratories that perform air-void system characterization typically have cabinets full of prepared samples with corresponding results from manual operators. Proponents of automated methods often take advantage of this fact by analyzing the same samples and comparing the results. A similar iterative approach is described here where scanned images collected from a significant number of samples are analyzed, the results compared to those of the manual operator, and the settings optimized to best approximate the results of the manual operator. The results of this calibration procedure are compared to an alternative calibration procedure based on the more rigorous digital image accuracy

Microstructural characterization of stone wool fibre network

DEFF Research Database (Denmark)

Chapelle, Lucie; Brøndsted, Povl; Kusano, Yukihiro

2014-01-01

Understanding the mechanical properties of fibrous network as complex as stone wool materials requires a relevant description of their microstructure and architecture. In this study, different methods have been proposed to characterize the fibre orientation, diameter and length of fibres as well...

Parametrization of Combined Quantum Mechanical and Molecular Mechanical Methods: Bond-Tuned Link Atoms

Directory of Open Access Journals (Sweden)

Xin-Ping Wu

2018-05-01

Full Text Available Combined quantum mechanical and molecular mechanical (QM/MM methods are the most powerful available methods for high-level treatments of subsystems of very large systems. The treatment of the QM−MM boundary strongly affects the accuracy of QM/MM calculations. For QM/MM calculations having covalent bonds cut by the QM−MM boundary, it has been proposed previously to use a scheme with system-specific tuned fluorine link atoms. Here, we propose a broadly parametrized scheme where the parameters of the tuned F link atoms depend only on the type of bond being cut. In the proposed new scheme, the F link atom is tuned for systems with a certain type of cut bond at the QM−MM boundary instead of for a specific target system, and the resulting link atoms are call bond-tuned link atoms. In principle, the bond-tuned link atoms can be as convenient as the popular H link atoms, and they are especially well adapted for high-throughput and accurate QM/MM calculations. Here, we present the parameters for several kinds of cut bonds along with a set of validation calculations that confirm that the proposed bond-tuned link-atom scheme can be as accurate as the system-specific tuned F link-atom scheme.

Parametrization of Combined Quantum Mechanical and Molecular Mechanical Methods: Bond-Tuned Link Atoms.

Science.gov (United States)

Wu, Xin-Ping; Gagliardi, Laura; Truhlar, Donald G

2018-05-30

Combined quantum mechanical and molecular mechanical (QM/MM) methods are the most powerful available methods for high-level treatments of subsystems of very large systems. The treatment of the QM-MM boundary strongly affects the accuracy of QM/MM calculations. For QM/MM calculations having covalent bonds cut by the QM-MM boundary, it has been proposed previously to use a scheme with system-specific tuned fluorine link atoms. Here, we propose a broadly parametrized scheme where the parameters of the tuned F link atoms depend only on the type of bond being cut. In the proposed new scheme, the F link atom is tuned for systems with a certain type of cut bond at the QM-MM boundary instead of for a specific target system, and the resulting link atoms are call bond-tuned link atoms. In principle, the bond-tuned link atoms can be as convenient as the popular H link atoms, and they are especially well adapted for high-throughput and accurate QM/MM calculations. Here, we present the parameters for several kinds of cut bonds along with a set of validation calculations that confirm that the proposed bond-tuned link-atom scheme can be as accurate as the system-specific tuned F link-atom scheme.

Quality control methods for linear accelerator radiation and mechanical axes alignment.

Science.gov (United States)

Létourneau, Daniel; Keller, Harald; Becker, Nathan; Amin, Md Nurul; Norrlinger, Bernhard; Jaffray, David A

2018-06-01

The delivery accuracy of highly conformal dose distributions generated using intensity modulation and collimator, gantry, and couch degrees of freedom is directly affected by the quality of the alignment between the radiation beam and the mechanical axes of a linear accelerator. For this purpose, quality control (QC) guidelines recommend a tolerance of ±1 mm for the coincidence of the radiation and mechanical isocenters. Traditional QC methods for assessment of radiation and mechanical axes alignment (based on pointer alignment) are time consuming and complex tasks that provide limited accuracy. In this work, an automated test suite based on an analytical model of the linear accelerator motions was developed to streamline the QC of radiation and mechanical axes alignment. The proposed method used the automated analysis of megavoltage images of two simple task-specific phantoms acquired at different linear accelerator settings to determine the coincidence of the radiation and mechanical isocenters. The sensitivity and accuracy of the test suite were validated by introducing actual misalignments on a linear accelerator between the radiation axis and the mechanical axes using both beam steering and mechanical adjustments of the gantry and couch. The validation demonstrated that the new QC method can detect sub-millimeter misalignment between the radiation axis and the three mechanical axes of rotation. A displacement of the radiation source of 0.2 mm using beam steering parameters was easily detectable with the proposed collimator rotation axis test. Mechanical misalignments of the gantry and couch rotation axes of the same magnitude (0.2 mm) were also detectable using the new gantry and couch rotation axis tests. For the couch rotation axis, the phantom and test design allow detection of both translational and tilt misalignments with the radiation beam axis. For the collimator rotation axis, the test can isolate the misalignment between the beam radiation axis

Benchmarking Quantum Mechanics/Molecular Mechanics (QM/MM) Methods on the Thymidylate Synthase-Catalyzed Hydride Transfer.

Science.gov (United States)

Świderek, Katarzyna; Arafet, Kemel; Kohen, Amnon; Moliner, Vicent

2017-03-14

Given the ubiquity of hydride-transfer reactions in enzyme-catalyzed processes, identifying the appropriate computational method for evaluating such biological reactions is crucial to perform theoretical studies of these processes. In this paper, the hydride-transfer step catalyzed by thymidylate synthase (TSase) is studied by examining hybrid quantum mechanics/molecular mechanics (QM/MM) potentials via multiple semiempirical methods and the M06-2X hybrid density functional. Calculations of protium and tritium transfer in these reactions across a range of temperatures allowed calculation of the temperature dependence of kinetic isotope effects (KIE). Dynamics and quantum-tunneling effects are revealed to have little effect on the reaction rate, but are significant in determining the KIEs and their temperature dependence. A good agreement with experiments is found, especially when computed for RM1/MM simulations. The small temperature dependence of quantum tunneling corrections and the quasiclassical contribution term cancel each other, while the recrossing transmission coefficient seems to be temperature-independent over the interval of 5-40 °C.

Characterization and mechanical separation of metals from computer Printed Circuit Boards (PCBs) based on mineral processing methods.

Science.gov (United States)

Sarvar, Mojtaba; Salarirad, Mohammad Mehdi; Shabani, Mohammad Amin

2015-11-01

In this paper, a novel mechanical process is proposed for enriching metal content of computer Printed Circuit Boards (PCBs). The PCBs are crushed and divided into three different size fractions namely: -0.59, +0.59 to 1.68 and +1.68 mm. Wet jigging and froth flotation methods are selected for metal enrichment. The coarse size fraction (+1.68 mm) is processed by jigging. The plastic free product is grinded and screened. The oversized product is separated as the first concentrate. It was rich of metal because the grinding process was selective. The undersized product is processed by froth flotation. Based on the obtained results, the middle size fraction (+0.59 to 1.68 mm) and the small size fraction (-0.59 mm) are processed by wet jigging and froth flotation respectively. The wet jigging process is optimized by investigating the effect of pulsation frequency and water flow rate. The results of examining the effect of particle size, solid to liquid ratio, conditioning time and using apolar collector showed that collectorless flotation is a promising method for separating nonmetals of PCBs. 95.6%, 97.5% and 85% of metal content of coarse size, middle size and small size fraction are recovered. The grades of obtained concentrates were 63.3%, 92.5% and 75% respectively. The total recovery is calculated as 95.64% and the grade of the final concentrate was 71.26%. Determining the grade of copper and gold in the final product reveals that 4.95% of copper and 24.46% of gold are lost during the concentration. The major part of the lost gold is accumulated in froth flotation tail. Copyright © 2015 Elsevier Ltd. All rights reserved.

Partly Duffing Oscillator Stochastic Resonance Method and Its Application on Mechanical Fault Diagnosis

Directory of Open Access Journals (Sweden)

Jian Dang

2016-01-01

Full Text Available Due to the fact that the slight fault signals in early failure of mechanical system are usually submerged in heavy background noise, it is unfeasible to extract the weak fault feature via the traditional vibration analysis. Stochastic resonance (SR, as a method of utilizing noise to amplify weak signals in nonlinear dynamical systems, can detect weak signals overwhelmed in the noise. However, based on the analysis of the impact of noise intensity on SR effect, it is concluded that the detection results are dramatically limited by the noise intensity of measured signals, especially for incipient fault feature of mechanical system with poor working environment. Therefore, this paper proposes a partly Duffing oscillator SR method to extract the fault feature of mechanical system. In this method, to locate the appearance of weak fault feature and decrease noise intensity, the permutation entropy index is constructed to select the measured signals for the input of Duffing oscillator system. Then, according to the regulation of system parameters, a reasonable match between the selected signals and Duffing oscillator model is achieved to produce a SR phenomenon and realize the fault diagnosis of mechanical system. Experiment results demonstrate that the proposed method achieves a better effect on the fault diagnosis of mechanical system.

Mechanical characterization of cemented carbide WC-6Co (%wt) manufactured by SPS (Spark Plasma Sintering; Caracterizacao mecanica de metal duro WC-6Co (%massa) sinterizado via SPS (Spark Plasma Sintering)

Energy Technology Data Exchange (ETDEWEB)

Boidi, G.; Tertuliano, A.J.; Machado, I.F., E-mail: guido.boidi@usp.br [Universidade de Sao Paulo (USP), SP (Brazil). Departamento de Engenharia Mecatronica e Sistemas Mecanicos; Rodrigues, D. [BRATS- Filtros Sinterizados e Pos Metalicos, Cajamar, SP (Brazil)

2016-07-01

This work aimed to manufacture cemented carbide (WC-6%wtCo) obtained by SPS (Spark Plasma Sintering) process and to carry out the mechanical characterization by hardness and fracture toughness. The material was consolidated at 1100 deg C for different holding times (1 min, 5 min, 10 min), in order to evaluate the densification. A reference sample was also used to be compared to SPS. Optical and scanning electron microscopy were carried out to characterize the microstructural features of the samples and mechanical properties were obtained by hardness measurements (micro and macro) and instrumented indentation. The fracture toughness was calculated with the method of Palmqvist. Best results were found in the material sintered by SPS for 10 minutes of holding time, in which 97% of relative density and about 1600 HV{sub 10} was reached. (author)

Comparison of Rice Direct Seeding Methods (Mechanical and Manual with Transplanting Method

Directory of Open Access Journals (Sweden)

A Eyvani

2014-04-01

Full Text Available The main method of rice planting in Iran is transplanting. Due to poor mechanization of rice production, this method is laborious and costly. The other method is direct seeding in wet lands which is performed in the one third of rice cultivation area of the world. The most important problem in this method is high labor requirement of weed control. In order to compare the different rice planting methods (direct drilling, transplanting, and seed broadcasting a manually operated rice direct seeder (drum seeder was designed and fabricated. The research was conducted using a randomized complete block design with three treatments and three replications. Required draft force, field efficiency, effective field capacity, yield, and yield components were measured and the treatments were compared economically. Results showed that there were significant differences among the treatments from the view point of rice yield at the confidence level of 95% i.e. the transplanting method had the maximum yield. A higher rice yield was obtained from the direct seeder compared to the manual broadcasting method but, the difference between these two methods for crop yield was not significant even at the confidence level of the 95%. The coefficient of variation of seed distribution with direct seeding was more than 20%. The labor and time requirements per hectare reduced to 7 and 20 times, respectively when comparing the newly designed direct seeder with the transplanting method. The direct seeding method had the highest benefit to cost ratio in spite of its lower yield. Therefore, this method could be recommended in the rice growing regions.

Mechanical and morphological characterizations of carbon fiber fabric reinforced epoxy composites used in aeronautical field

Directory of Open Access Journals (Sweden)

Jane Maria Faulstich de Paiva

2009-09-01

Full Text Available Carbon fiber reinforced composites (CFRC have been used in aeronautical industry in the manufacture of different aircraft components that must attend tight mechanical requirements. This paper shows a study involving mechanical (flexural, shear, tensile and compressive tests and morphological characterizations of four different laminates based on 2 epoxy resin systems (8552TM and F584TM and 2 carbon fiber fabric reinforcements (Plain Weave (PW and Eight Harness Satin (8HS. All laminates were obtained by handing lay-up of prepregs plies (0º/90º and consolidation in an autoclave following an appropriate curing cycle with vacuum and pressure. The results show that the F584-epoxy matrix laminates present better mechanical properties in the tensile and compressive tests than 8552 composites. It is also observed that PW laminates for both matrices show better flexural and interlaminar shear properties.

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.  

Synthesis and characterization of eggshell-derived hydroxyapatite via mechanochemical method: A comparative study

Science.gov (United States)

Hamidi, A. A.; Salimi, M. N.; Yusoff, A. H. M.

2017-04-01

The focus of bone graft properties has developed through generations, from the ability to withstand mechanical stress to the ability to integrate with the biological structure. In recent years, the use of hydroxyapatite (HA) as bone graft material in orthopedic and dental applications has been increasing. HA is a natural occuring mineral with excellent bioactivity but relatively poor mechanical properties. It constitutes 96% portion of enamel in teeth and 67% portion of bone. HA can be extracted from animal bones or fabricated from synthetic or biologic sources. In this study, eggshells were used as raw material to synthesize eggshell-derived HA (EHA) via mechanochemical method. The synthesis of EHA involved CaO, which was obtained from the calcination of eggshells, and reaction with dicalcium hydrogen phosphate dihydrous (DCPD) or phosphoric acid (H3PO4). The effects of rotational speed and heat treatment temperature on EHA's characteristics were investigated. The characterization studies were carried out by using the Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD) analysis and Scanning Electron Microscopy (SEM). HA powder was successfully synthesized with crystallite and particle sizes in the range of 8-47 nm and 250-550 nm respectively. It was observed from this study that the increase of milling rotational speed had increased the phase purity of EHA samples. Furthermore, the higher heating temperature of HA samples resulted in higher degree of crystallinity of HA and the appearance of β-tricalcium phosphate (β-TCP) as secondary phase.

Characterizing cellular mechanical phenotypes with mechano-node-pore sensing

Science.gov (United States)

Kim, Junghyun; Han, Sewoon; Lei, Andy; Miyano, Masaru; Bloom, Jessica; Srivastava, Vasudha; Stampfer, Martha M.; Gartner, Zev J.; LaBarge, Mark A.; Sohn, Lydia L.

2018-01-01

The mechanical properties of cells change with their differentiation, chronological age, and malignant progression. Consequently, these properties may be useful label-free biomarkers of various functional or clinically relevant cell states. Here, we demonstrate mechano-node-pore sensing (mechano-NPS), a multi-parametric single-cell-analysis method that utilizes a four-terminal measurement of the current across a microfluidic channel to quantify simultaneously cell diameter, resistance to compressive deformation, transverse deformation under constant strain, and recovery time after deformation. We define a new parameter, the whole-cell deformability index (wCDI), which provides a quantitative mechanical metric of the resistance to compressive deformation that can be used to discriminate among different cell types. The wCDI and the transverse deformation under constant strain show malignant MCF-7 and A549 cell lines are mechanically distinct from non-malignant, MCF-10A and BEAS-2B cell lines, and distinguishes between cells treated or untreated with cytoskeleton-perturbing small molecules. We categorize cell recovery time, ΔTr, as instantaneous (ΔTr ~ 0 ms), transient (ΔTr ≤ 40ms), or prolonged (ΔTr > 40ms), and show that the composition of recovery types, which is a consequence of changes in cytoskeletal organization, correlates with cellular transformation. Through the wCDI and cell-recovery time, mechano-NPS discriminates between sub-lineages of normal primary human mammary epithelial cells with accuracy comparable to flow cytometry, but without antibody labeling. Mechano-NPS identifies mechanical phenotypes that distinguishes lineage, chronological age, and stage of malignant progression in human epithelial cells. PMID:29780657

A practical iterative PID tuning method for mechanical systems using parameter chart

Science.gov (United States)

Kang, M.; Cheong, J.; Do, H. M.; Son, Y.; Niculescu, S.-I.

2017-10-01

In this paper, we propose a method of iterative proportional-integral-derivative parameter tuning for mechanical systems that possibly possess hidden mechanical resonances, using a parameter chart which visualises the closed-loop characteristics in a 2D parameter space. We employ a hypothetical assumption that the considered mechanical systems have their upper limit of the derivative feedback gain, from which the feasible region in the parameter chart becomes fairly reduced and thus the gain selection can be extremely simplified. Then, a two-directional parameter search is carried out within the feasible region in order to find the best set of parameters. Experimental results show the validity of the assumption used and the proposed parameter tuning method.

Computer based ultrasonic system for mechanical and acoustical characterization of materials

International Nuclear Information System (INIS)

Rosly Jaafar; Mohd Rozni Mohd Yusof; Khaidzir Hamzah; Md Supar Rohani; Rashdi Shah Ahmad; Amiruddin Shaari

2001-01-01

Propagation of both modes of ultrasonic waves velocity i.e. longitudinal (compressional) and transverse (shear), propagating in a material are closely linked with the material's physical and mechanical properties. By measuring both velocity modes, materials' properties such as Young's, bulk and shear moduli, compressibility, Poisson ratio and acoustic impedance can be determined. This paper describes the development of a system that is able to perform the above tasks and is known as Computer Based Ultrasonic for Mechanical and Acoustical Characterisation of Materials (UMC). The system was developed in the NDT Instrumentation and Signal Processing (NDTSP) laboratory of the Physics Department, Universiti Teknologi Malaysia. Measurements were made on four solid samples, namely, glass, copper, mild steel and aluminium. The results of measurements obtained were found to be in good agreement with the values of measurements made using standard methods. The main advantage of using this system over other methods is that single measurement of two ultrasonic velocity modes yields six material's properties. (Author)

A path flux analysis method for the reduction of detailed chemical kinetic mechanisms

Energy Technology Data Exchange (ETDEWEB)

Sun, Wenting; Ju, Yiguang [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Chen, Zheng [State Key Laboratory for Turbulence and Complex Systems, College of Engineering, Peking University, Beijing 100871 (China); Gou, Xiaolong [School of Power Engineering, Chongqing University, Chongqing 400044 (China)

2010-07-15

A direct path flux analysis (PFA) method for kinetic mechanism reduction is proposed and validated by using high temperature ignition, perfect stirred reactors, and steady and unsteady flame propagations of n-heptane and n-decane/air mixtures. The formation and consumption fluxes of each species at multiple reaction path generations are analyzed and used to identify the important reaction pathways and the associated species. The formation and consumption path fluxes used in this method retain flux conservation information and are used to define the path indexes for the first and the second generation reaction paths related to a targeted species. Based on the indexes of each reaction path for the first and second generations, different sized reduced chemical mechanisms which contain different number of species are generated. The reduced mechanisms of n-heptane and n-decane obtained by using the present method are compared to those generated by the direct relation graph (DRG) method. The reaction path analysis for n-decane is conducted to demonstrate the validity of the present method. The comparisons of the ignition delay times, flame propagation speeds, flame structures, and unsteady spherical flame propagation processes showed that with either the same or significantly less number of species, the reduced mechanisms generated by the present PFA are more accurate than that of DRG in a broad range of initial pressures and temperatures. The method is also integrated with the dynamic multi-timescale method and a further increase of computation efficiency is achieved. (author)

Quantum Mechanics/Molecular Mechanics Method Combined with Hybrid All-Atom and Coarse-Grained Model: Theory and Application on Redox Potential Calculations.

Science.gov (United States)

Shen, Lin; Yang, Weitao

2016-04-12

We developed a new multiresolution method that spans three levels of resolution with quantum mechanical, atomistic molecular mechanical, and coarse-grained models. The resolution-adapted all-atom and coarse-grained water model, in which an all-atom structural description of the entire system is maintained during the simulations, is combined with the ab initio quantum mechanics and molecular mechanics method. We apply this model to calculate the redox potentials of the aqueous ruthenium and iron complexes by using the fractional number of electrons approach and thermodynamic integration simulations. The redox potentials are recovered in excellent accordance with the experimental data. The speed-up of the hybrid all-atom and coarse-grained water model renders it computationally more attractive. The accuracy depends on the hybrid all-atom and coarse-grained water model used in the combined quantum mechanical and molecular mechanical method. We have used another multiresolution model, in which an atomic-level layer of water molecules around redox center is solvated in supramolecular coarse-grained waters for the redox potential calculations. Compared with the experimental data, this alternative multilayer model leads to less accurate results when used with the coarse-grained polarizable MARTINI water or big multipole water model for the coarse-grained layer.

Filtration Characterization Method as Tool to Assess Membrane Bioreactor Sludge Filterability—The Delft Experience

Directory of Open Access Journals (Sweden)

Maria Lousada-Ferreira

2014-04-01

Full Text Available Prevention and removal of fouling is often the most energy intensive process in Membrane Bioreactors (MBRs, responsible for 40% to 50% of the total specific energy consumed in submerged MBRs. In the past decade, methods were developed to quantify and qualify fouling, aiming to support optimization in MBR operation. Therefore, there is a need for an evaluation of the lessons learned and how to proceed. In this article, five different methods for measuring MBR activated sludge filterability and critical flux are described, commented and evaluated. Both parameters characterize the fouling potential in full-scale MBRs. The article focuses on the Delft Filtration Characterization method (DFCm as a convenient tool to characterize sludge properties, namely on data processing, accuracy, reproducibility, reliability, and applicability, defining the boundaries of the DFCm. Significant progress was made concerning fouling measurements in particular by using straight forward approaches focusing on the applicability of the obtained results. Nevertheless, a fouling measurement method is still to be defined which is capable of being unequivocal, concerning the fouling parameters definitions; practical and simple, in terms of set-up and operation; broad and useful, in terms of obtained results. A step forward would be the standardization of the aforementioned method to assess the sludge filtration quality.

J evaluation by simplified method for cracked pipes under mechanical loading

International Nuclear Information System (INIS)

Lacire, M.H.; Michel, B.; Gilles, P.

2001-01-01

The integrity of structures behaviour is an important subject for the nuclear reactor safety. Most of assessment methods of cracked components are based on the evaluation of the parameter J. However to avoid complex elastic-plastic finite element calculations of J, a simplified method has been jointly developed by CEA, EDF and Framatome. This method, called Js, is based on the reference stress approach and a new KI handbook. To validate this method, a complete set of 2D and 3D elastic-plastic finite element calculations of J have been performed on pipes (more than 300 calculations are available) for different types of part through wall crack (circumferential or longitudinal); mechanical loading (pressure, bending moment, axial load, torsion moment, and combination of these loading); different kind of materials (austenitic or ferritic steel). This paper presents a comparison between the simplified assessment of J and finite element results on these configurations for mechanical loading. Then, validity of the method is discussed and an applicability domain is proposed. (author)

Characterization of HEM silicon for solar cells. [Heat Exchanger Method

Science.gov (United States)

Dumas, K. A.; Khattak, C. P.; Schmid, F.

1981-01-01

The Heat Exchanger Method (HEM) is a promising low-cost ingot casting process for material used for solar cells. This is the only method that is capable of casting single crystal ingots with a square cross section using a directional solidification technique. This paper describes the chemical, mechanical and electrical properties of the HEM silicon material as a function of position within the ingot.

Mechanical characterization of a reduced activation 9 Cr ferritic/martensitic steel of spanish production

International Nuclear Information System (INIS)

Rodriguez, D.; Serrano, M.

2012-01-01

This paper shows the first results concerning the characterization of two heats of a reduced activation 9 Cr ferritic/martensitic steel (RAFM) made in Spain, called AF1B and AF2A. The results of this characterization are compared with their European counterparts, EUROFER97-2, which was chosen as reference material. All activities described were performed in the Structural Materials Unit of CIEMAT, within the national project TECNO-FUS CONSOLIDER INGENIO.The two Spanish heats have the same production process and heat treatment. Both heats have a similar tensile behaviour similar to EUROFER97-2, but on the other hand impact properties are lower. The microstructure of AF1B reveals large biphasic inclusions that affecting its mechanical properties, especially the impact properties. AF2A casting was free of these inclusions. (Author) 24 refs.

Experimental characterization of the hydro-mechanical behaviour of Meuse/Haute-Marne argilites

International Nuclear Information System (INIS)

Escoffier, S.

2002-04-01

Within the framework of a feasibility study of underground radioactive waste repository the experimental characterization of the coupled behavior of the host layer is of first importance. This work concerns the experimental characterization in laboratory of the poro-elastic behavior of argillite which constitutes the host layer of the future underground laboratory of ANDRA located at the limit of the Meuse/Haute-Marne. The theoretical approach is the Mechanics of Porous Media defined by Coussy [1991] which has the advantage of providing a formulation of the behavior laws using measurable parameters in laboratory. The difficulties or the feasibility of the characterization tests of these rocks coupled behavior are related to their very low permeability which requires an adaptation of the experimental devices initially used on more permeable rocks. Initially a synthesis on the knowledge of the poro-elastic parameters of Meuse/Haute-Marne argillite is given. Thereafter a first approach of the use of the studies of sensitivity as tools of decision-making aid is proposed. The experimental difficulties encountered by the various experimenters are illustrated by the diversity of the experimental choices, the test duration or by the results disparity. Because of economic, political and ecological stake, the studies of sensitivity could make it possible to direct the experimental efforts by giving indications on the dominating parameters in the coupled behavior of a rock. In the second time after the presentation of the test results of physical characterization 3 types of tests are described: permeability test (pulse test), determination of Biot coefficient under odometric loading and isotropic drained test. The complexity of these tests is related to the attack of the experimental limits. They are presented in detail: theoretical recalls, experimental set up, experimental protocol, unfolding and test results. (author)

Manufacture and characterization of austenitic steel welded joints. Joint final report - Vol. 1

International Nuclear Information System (INIS)

Simoni, O.; Boerman, D.J.; Krischer, W.

1990-07-01

This report describes the results of the first phase of the project, i.e. manufacturing and characterization of welded austenitic steel and the test matrix adopted to test the mechanical resistance of the weldings. Five different welding methods have been produced and characterized in comparison to the parent material. The reference material was an AISI 316L type steel close to the French Superphenix composition. The results of the mechanical testing and the relative comparison of the five welding methods are described in a second volume. As a general conclusion, the vacuum electron-beam welding proved to have better properties than the other weld methods and to attain in most cases the properties of the parent material

In vitro characterization of hydroxyapatite layers deposited by APS and HVOF thermal spraying methods

Directory of Open Access Journals (Sweden)

Radu Alexandru Roşu

2012-03-01

Full Text Available Titanium alloys are successfully used in medicine as implants due to their high mechanical properties and good biocompatibility. To improve implant osseointegration of titanium alloys, they are covered with hydroxyapatite because of its bioactive properties. Coating the implants with hydroxyapatite by thermal spraying, due to the temperatures developed during the deposition process, the structure can be degraded, leading to formation of secondary phases, such as TCP, TT CP, CaO. The paper presents the experimental results of hydroxyapatite layers deposition by two thermal spraying methods: Atmospheric Plasma Spraying (APS and High Velocity Oxy-Fuel (HVOF. The microstructure of the deposited layers is characterized by X-ray diffraction analysis and electronic microscopy. The bioactivity of the hydroxyapatite layers was investigated in Simulated Body Fluid (SBF by immersing the covered samples deposited by the two thermal spraying methods. In both cases the coatings did not present defects as cracks or microcracks. X-ray diffraction performed on hydroxyapatite deposited layers shows that the structure was strongly influenced by plasma jet temperature, the structure consisting mainly of TCP (Ca3PO42. The samples deposited by HVO F after immersing in SBF lead to formation of biological hydroxyapatite, certifying the good bioactivity of the coatings.

Current measurement method for characterization of fast switching power semiconductors with Silicon Steel Current Transformer

DEFF Research Database (Denmark)

Li, Helong; Beczkowski, Szymon; Munk-Nielsen, Stig

2015-01-01

This paper proposes a novel current measurement method with Silicon Steel Current Transformer (SSCT) for the characterization of fast switching power semiconductors. First, the existing current sensors for characterization of fast switching power semiconductors are experimentally evaluated...

Building block method: a bottom-up modular synthesis methodology for distributed compliant mechanisms

Directory of Open Access Journals (Sweden)

G. Krishnan

2012-03-01

Full Text Available Synthesizing topologies of compliant mechanisms are based on rigid-link kinematic designs or completely automated optimization techniques. These designs yield mechanisms that match the kinematic specifications as a whole, but seldom yield user insight on how each constituent member contributes towards the overall mechanism performance. This paper reviews recent developments in building block based design of compliant mechanisms. A key aspect of such a methodology is formulating a representation of compliance at a (i single unique point of interest in terms of geometric quantities such as ellipses and vectors, and (ii relative compliance between distinct input(s and output(s in terms of load flow. This geometric representation provides a direct mapping between the mechanism geometry and their behavior, and is used to characterize simple deformable members that form a library of building blocks. The design space spanned by the building block library guides the decomposition of a given problem specification into tractable sub-problems that can be each solved from an entry in the library. The effectiveness of this geometric representation aids user insight in design, and enables discovery of trends and guidelines to obtain practical conceptual designs.

Synthesis by irradiation and mechanism and structural characterization study of high melt strength polypropylene

International Nuclear Information System (INIS)

Lugao, Ademar Benevolo

2004-01-01

Polypropylene molecular structure is made only by linear molecules interacting by weak forces. The resulting PP has very low melt strength (MS). MS is important to make feasible to process PP by all the transformation technologies based on the free expansion of the melt. The aim of this work was to develop a new process to synthesize PP with crosslinks and/or long chain branches, known as High Melt Strength Polypropylene (HMSPP) and to characterize its structure and synthesis mechanism. HMSPP was obtained by the irradiation of PP under a crosslinking (acetylene) atmosphere or inert or oxidative one, followed by thermal treatment for radical recombination and thermal treatment for annihilation of the remaining radicals under reactive or inert atmosphere. The results from rheological characterization showed that the highest levels of MS were obtained by conducting irradiation and thermal treatments under crosslinking atmospheres. The results for the elucidation of reaction mechanism by electron spin resonance (ESR) showed that acetylene irradiation is effective in promoting the creation of double bonds, based on the formation of polyenil radicals. The results of structural unraveling showed that radiation promotes predominantly the degradation of atactic molecules or molecules with atactic defects. These results support the hypothesis of formation of branched PP molecules based on the reaction of those fragments with the double bonds created in the PP molecules. (author)

Mechanical stability of heat-treated nanoporous anodic alumina subjected to repetitive mechanical deformation

Science.gov (United States)

Bankova, A.; Videkov, V.; Tzaneva, B.; Mitov, M.

2018-03-01

We report studies on the mechanical response and deformation behavior of heat-treated nanoporous anodic alumina using a micro-balance test and experimental test equipment especially designed for this purpose. AAO samples were characterized mechanically by a three-point bending test using a micro-analytical balance. The deformation behavior was studied by repetitive mechanical bending of the AAO membranes using an electronically controlled system. The nanoporous AAO structures were prepared electrochemically from Al sheet substrates using a two-step anodizing technique in oxalic acid followed by heat treatment at 700 °C in air. The morphological study of the aluminum oxide layer after the mechanical tests and mechanical deformation was conducted using scanning electron and optical microscopy, respectively. The experimental results showed that the techniques proposed are simple and accurate; they could, therefore, be combined to constitute a method for mechanical stability assessment of nanostructured AAO films, which are important structural components in the design of MEMS devices and sensors.

Reagentless mechanical cell lysis by nanoscale barbs in microchannels for sample preparation.

Science.gov (United States)

Di Carlo, Dino; Jeong, Ki-Hun; Lee, Luke P

2003-11-01

A highly effective, reagentless, mechanical cell lysis device integrated in microfluidic channels is reported. Sample preparation, specifically cell lysis, is a critical element in 'lab-on-chip' applications. However, traditional methods of cell lysis require purification steps or complicated fabrication steps that a simple mechanical method of lysis may avoid. A simple and effective mechanical cell lysis system is designed, microfabricated, and characterized to quantify the efficiency of cell lysis and biomolecule accessibility. The device functionality is based on a microfluidic filter region with nanostructured barbs created using a modified deep reactive ion etching process. Mechanical lysis is characterized by using a membrane impermeable dye. Three main mechanisms of micro-mechanical lysis are described. Quantitative measurements of accessible protein as compared to a chemically lysed sample are acquired with optical absorption measurements at 280 and 414 nm. At a flow rate of 300 microL min(-1) within the filter region total protein and hemoglobin accessibilities of 4.8% and 7.5% are observed respectively as compared to 1.9% and 3.2% for a filter without nanostructured barbs.

An adaptive quantum mechanics/molecular mechanics method for the infrared spectrum of water: incorporation of the quantum effect between solute and solvent.

Science.gov (United States)

Watanabe, Hiroshi C; Banno, Misa; Sakurai, Minoru

2016-03-14

Quantum effects in solute-solvent interactions, such as the many-body effect and the dipole-induced dipole, are known to be critical factors influencing the infrared spectra of species in the liquid phase. For accurate spectrum evaluation, the surrounding solvent molecules, in addition to the solute of interest, should be treated using a quantum mechanical method. However, conventional quantum mechanics/molecular mechanics (QM/MM) methods cannot handle free QM solvent molecules during molecular dynamics (MD) simulation because of the diffusion problem. To deal with this problem, we have previously proposed an adaptive QM/MM "size-consistent multipartitioning (SCMP) method". In the present study, as the first application of the SCMP method, we demonstrate the reproduction of the infrared spectrum of liquid-phase water, and evaluate the quantum effect in comparison with conventional QM/MM simulations.

On characterizing the mechanical properties of aluminum–alumina composites

International Nuclear Information System (INIS)

Gudlur, Pradeep; Boczek, Artur; Radovic, Miladin; Muliana, Anastasia

2014-01-01

The overall response of aluminum–alumina (Al–Al 2 O 3 ) composites depends strongly on their microstructural characteristics. We study the overall mechanical response of Al–Al 2 O 3 composites experimentally, using Resonant Ultrasound Spectroscopy (RUS) and uniaxial compressive testing. Microstructures of composite with 10% alumina volume content are constructed from the microstructural images of the composite obtained from scanning electron microscopy (SEM). The SEM images of the composite are converted to finite element (FE) meshes, which are used to solve the boundary value problem in order to determine the overall mechanical response of the Al–Al 2 O 3 composite. The responses generated from the micromechanical models are compared with the elastic modulus obtained from RUS and experimental stress–strain curves from uniaxial compression tests. Effects of processing, porosity, alumina content, thermal (residual) stress, and plastic deformation on the overall elastic modulus and response of the composites are also studied. We observed that slightly altering the processing method had a significant effect on the microstructural characteristics and in turn on the overall physical and mechanical properties of the composite. With changes in porosity by 2–3%, the elastic modulus was found to vary by 10–15 GPa approximately. We observed that the elastic moduli of the composites determined from the uniaxial compressive tests are close to those obtained from RUS

A method for generating reduced-order combustion mechanisms that satisfy the differential entropy inequality

Science.gov (United States)

Ream, Allen E.; Slattery, John C.; Cizmas, Paul G. A.

2018-04-01

This paper presents a new method for determining the Arrhenius parameters of a reduced chemical mechanism such that it satisfies the second law of thermodynamics. The strategy is to approximate the progress of each reaction in the reduced mechanism from the species production rates of a detailed mechanism by using a linear least squares method. A series of non-linear least squares curve fittings are then carried out to find the optimal Arrhenius parameters for each reaction. At this step, the molar rates of production are written such that they comply with a theorem that provides the sufficient conditions for satisfying the second law of thermodynamics. This methodology was used to modify the Arrhenius parameters for the Westbrook and Dryer two-step mechanism and the Peters and Williams three-step mechanism for methane combustion. Both optimized mechanisms showed good agreement with the detailed mechanism for species mole fractions and production rates of most major species. Both optimized mechanisms showed significant improvement over previous mechanisms in minor species production rate prediction. Both optimized mechanisms produced no violations of the second law of thermodynamics.

Sandwich Structured Composites for Aeronautics: Methods of Manufacturing Affecting Some Mechanical Properties

Directory of Open Access Journals (Sweden)

Aneta Krzyżak

2016-01-01

Full Text Available Sandwich panels are composites which consist of two thin laminate outer skins and lightweight (e.g., honeycomb thick core structure. Owing to the core structure, such composites are distinguished by stiffness. Despite the thickness of the core, sandwich composites are light and have a relatively high flexural strength. These composites have a spatial structure, which affects good thermal insulator properties. Sandwich panels are used in aeronautics, road vehicles, ships, and civil engineering. The mechanical properties of these composites are directly dependent on the properties of sandwich components and method of manufacturing. The paper presents some aspects of technology and its influence on mechanical properties of sandwich structure polymer composites. The sandwiches described in the paper were made by three different methods: hand lay-up, press method, and autoclave use. The samples of sandwiches were tested for failure caused by impact load. Sandwiches prepared in the same way were used for structural analysis of adhesive layer between panels and core. The results of research showed that the method of manufacturing, more precisely the pressure while forming sandwich panels, influences some mechanical properties of sandwich structured polymer composites such as flexural strength, impact strength, and compressive strength.

Preparation, Characterization and Analysis of Fouling Mechanisms of TiO2- Embedded PVDF Membranes

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Yoones Jafarzadeh

2017-01-01

Full Text Available Titanium dioxide (TiO2-embedded polyvinylidene fluoride (PVDF mixed matrix membranes were prepared through a nonsolvent induced phase separation (NIPS method. The structure of the membranes was characterized by FESEM, EDX, water drop contact angle measurement, pure water flux and mean pore radius analysis. The results showed that the prepared membranes had asymmetric structures with macro-voids and the presence of TiO2 nanoparticles increased the size of macro-voids. Moreover, pure water flux increased from 41 kg/m2h to 162 kg/m2h the content of TiO2 nanoparticles increased from 1 wt% to 5 wt% as embedded membrane. The contact angle dropped from 100° for 1 wt% TiO2- embedded membrane to 69° for 5 wt% TiO2-embedded membrane, showing that the hydrophilicity of membranes increased by addition of inorganic TiO2 nanoparticles. The fouling behavior oftheprepared mixed matrix membranes was studied in filtration process of 1% humic acid solution. The results showed that fouling resistance of the membranes increased with higher content of TiO2 nanoparticles. The results of classic fouling modeling of membranes showed that for 2 and 5 wt% TiO2-embedded membranes the best fit of the data occurred with the intermediate blockage model whereas cake formation model was the dominant mechanism for other membranes. Moreover, the analysis of fouling mechanisms by combined models showed that cake filtration-intermediate blockage model was in good agreement with the experimental data for all membranes. Finally, the results showed that the rejection of membranes increased with the addition of TiO2 nanoparticles, and then decreased.

Optimisation Methods for Cam Mechanisms

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Claudia–Mari Popa

2010-01-01

Full Text Available In this paper we present the criteria which represent the base of optimizing the cam mechanisms and also we perform the calculations for several types of mechanisms. We study the influence of the constructive parameters in case of the simple machines with rotation cam and follower (flat or curve of translation on the curvature radius and that of the transmission angle. As it follows, we present the optimization calculations of the cam and flat rotation follower mechanisms, as well as the calculations for optimizing the cam mechanisms by circular groove followers’ help. For an easier interpretation of the results, we have visualized the obtained cam in AutoCAD according to the script files generated by a calculation program.

Mechanical characterization and non-linear elastic modeling of poly(glycerol sebacate) for soft tissue engineering.

Science.gov (United States)

Mitsak, Anna G; Dunn, Andrew M; Hollister, Scott J

2012-07-01

Scaffold tissue engineering strategies for repairing and replacing soft tissue aim to improve reconstructive and corrective surgical techniques whose limitations include suboptimal mechanical properties, fibrous capsule formation and volume loss due to graft resorption. An effective tissue engineering strategy requires a scaffolding material with low elastic modulus that behaves similarly to soft tissue, which has been characterized as a nonlinear elastic material. The material must also have the ability to be manufactured into specifically designed architectures. Poly(glycerol sebacate) (PGS) is a thermoset elastomer that meets these criteria. We hypothesize that the mechanical properties of PGS can be modulated through curing condition and architecture to produce materials with a range of stiffnesses. To evaluate this hypothesis, we manufactured PGS constructs cured under various conditions and having one of two architectures (solid or porous). Specimens were then tensile tested according to ASTM standards and the data were modeled using a nonlinear elastic Neo-Hookean model. Architecture and testing conditions, including elongation rate and wet versus dry conditions, affected the mechanical properties. Increasing curing time and temperature led to increased tangent modulus and decreased maximum strain for solid constructs. Porous constructs had lower nonlinear elastic properties, as did constructs of both architectures tested under simulated physiological conditions (wetted at 37 °C). Both solid and porous PGS specimens could be modeled well with the Neo-Hookean model. Future studies include comparing PGS properties to other biological tissue types and designing and characterizing PGS scaffolds for regenerating these tissues. Copyright © 2012 Elsevier Ltd. All rights reserved.

Introduction to optical methods for characterizing liquid crystals at interfaces.

Science.gov (United States)

Miller, Daniel S; Carlton, Rebecca J; Mushenheim, Peter C; Abbott, Nicholas L

2013-03-12

This Instructional Review describes methods and underlying principles that can be used to characterize both the orientations assumed spontaneously by liquid crystals (LCs) at interfaces and the strength with which the LCs are held in those orientations (so-called anchoring energies). The application of these methods to several different classes of LC interfaces is described, including solid and aqueous interfaces as well as planar and nonplanar interfaces (such as those that define a LC-in-water emulsion droplet). These methods, which enable fundamental studies of the ordering of LCs at polymeric, chemically functionalized, and biomolecular interfaces, are described in this Instructional Review on a level that can be easily understood by a nonexpert reader such as an undergraduate or graduate student. We focus on optical methods because they are based on instrumentation that is found widely in research and teaching laboratories.

Mechanical characterization of W-armoured plasma-facing components after thermal fatigue

International Nuclear Information System (INIS)

Serret, D; Richou, M; Missirlian, M; Loarer, T

2011-01-01

The future fusion device ITER is aimed at demonstrating the scientific and technical feasibility of fusion power. Tens of thousands of W-armoured plasma-facing components (PFCs) will be installed in the vertical targets of the ITER divertor and subjected to a high heat flux. The purpose of this paper is to present the results of mechanical and microstructural characterization of tungsten PFCs after thermal fatigue tests. On each component, Vickers hardness measurements are made. In parallel, the mean grain diameter in the corresponding zone of tungsten material is determined. The empirical Hall-Petch relation was adapted to experimental data. However, due to the plateau effect on recrystallization hardness, this relation does not seem to be relevant once recrystallization is complete: a new approach is proposed for predicting the margin to the tungsten melting onset.

Characterization of mechanical behavior of an epithelial monolayer in response to epidermal growth factor stimulation

International Nuclear Information System (INIS)

Yang, Ruiguo; Chen, Jennifer Y.; Xi, Ning; Lai, King Wai Chiu; Qu, Chengeng; Fung, Carmen Kar Man; Penn, Lynn S.; Xi, Jun

2012-01-01

Cell signaling often causes changes in cellular mechanical properties. Knowledge of such changes can ultimately lead to insight into the complex network of cell signaling. In the current study, we employed a combination of atomic force microscopy (AFM) and quartz crystal microbalance with dissipation monitoring (QCM-D) to characterize the mechanical behavior of A431 cells in response to epidermal growth factor receptor (EGFR) signaling. From AFM, which probes the upper portion of an individual cell in a monolayer of cells, we observed increases in energy dissipation, Young's modulus, and hysteresivity. Increases in hysteresivity imply a shift toward a more fluid-like mechanical ordering state in the bodies of the cells. From QCM-D, which probes the basal area of the monolayer of cells collectively, we observed decreases in energy dissipation factor. This result suggests a shift toward a more solid-like state in the basal areas of the cells. The comparative analysis of these results indicates a regionally specific mechanical behavior of the cell in response to EGFR signaling and suggests a correlation between the time-dependent mechanical responses and the dynamic process of EGFR signaling. This study also demonstrates that a combination of AFM and QCM-D is able to provide a more complete and refined mechanical profile of the cells during cell signaling. -- Highlights: ► The EGF-induced cellular mechanical response is regionally specific. ► The EGF-induced cellular mechanical response is time and dose dependent. ► A combination of AFM and QCM-D provides a more complete mechanical profile of cells.

Geo-Mechanical Characterization of Carbonate Rock Masses by Means of Laser Scanner Technique

Science.gov (United States)

Palma, Biagio; Parise, Mario; Ruocco, Anna

2017-12-01

Knowledge of the geometrical and structural setting of rock masses is crucial to evaluate the stability and to design the most suitable stabilization works. In this work we use the Terrestrial Laser Scanning (TLS) at the site of the Grave of the Castellana Caves, a famous show cave in southern Italy. The Grave is the natural access to the cave system, produced by collapse of the vault, due to upward progression of instabilities in the carbonate rock masses. It is about 55-m high, bell-shaped, with maximum width of 120 m. Aim of the work is the characterization of carbonate rock masses from the structural and geo-mechanical standpoints through the use of innovative survey techniques. TLS survey provides a product consisting of millions of geo-referenced points, to be managed in space, to become a suitable database for the morphological and geological-structural analysis. Studying by means of TLS a rock face, partly inaccessible or located in very complex environments, allows to investigate slopes in their overall areal extent, thus offering advantages both as regards safety of the workers and time needed for the survey. In addition to TLS, the traditional approach was also followed by performing scanlines surveys along the rims of the Grave, following the ISRM recommendations for characterization of discontinuity in rock masses. A quantitative comparison among the data obtained by TLS technique and those deriving from the classical geo-mechanical survey is eventually presented, to discuss potentiality of drawbacks of the different techniques used for surveying the rock masses.

Characterization of mechanical properties and microstructure of highly irradiated SS 316

Energy Technology Data Exchange (ETDEWEB)

Karthik, V., E-mail: karthik@igcar.gov.in [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Kumar, RanVijay; Vijayaragavan, A.; Venkiteswaran, C.N.; Anandaraj, V.; Parameswaran, P.; Saroja, S.; Muralidharan, N.G.; Joseph, Jojo; Kasiviswanathan, K.V.; Jayakumar, T.; Raj, Baldev [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

2013-08-15

Cold worked austenitic stainless steel type AISI 316 is used as the material for fuel cladding and wrapper of the Fast Breeder Test Reactor (FBTR), India. The evaluation of mechanical properties of these core structurals is very essential to assess its integrity and ensure safe and productive operation of FBTR to very high burn-ups. The changes in the mechanical properties of these core structurals are associated with microstructural changes caused by high fluence neutron irradiation and temperatures of 673–823 K. Remote tensile testing has been used for evaluating the tensile properties of irradiated clad tubes and shear punch test using small disk specimens for evaluating the properties of irradiated hexagonal wrapper. This paper will highlight the methods employed for evaluating the mechanical properties of the irradiated cladding and wrapper and discuss the trends in properties as a function of dpa (displacement per atom) and irradiation temperature.

Methodologies of Knowledge Discovery from Data and Data Mining Methods in Mechanical Engineering

Directory of Open Access Journals (Sweden)

Rogalewicz Michał

2016-12-01

Full Text Available The paper contains a review of methodologies of a process of knowledge discovery from data and methods of data exploration (Data Mining, which are the most frequently used in mechanical engineering. The methodologies contain various scenarios of data exploring, while DM methods are used in their scope. The paper shows premises for use of DM methods in industry, as well as their advantages and disadvantages. Development of methodologies of knowledge discovery from data is also presented, along with a classification of the most widespread Data Mining methods, divided by type of realized tasks. The paper is summarized by presentation of selected Data Mining applications in mechanical engineering.

Characterization of the mechanical properties of a dermal equivalent compared with human skin in vivo by indentation and static friction tests.

Science.gov (United States)

Zahouani, H; Pailler-Mattei, C; Sohm, B; Vargiolu, R; Cenizo, V; Debret, R

2009-02-01

The study of changes in skin structure with age is becoming all the more important with the increase in life. The atrophy that occurs during aging is accompanied by more profound changes, with a loss of organization within the elastic collagen network and alterations in the basal elements. The aim of this study is to present a method to determine the mechanical properties of total human skin in vivo compared with dermal equivalents (DEs) using indentation and static friction tests. A new bio-tribometer working at a low contact pressure for the characterization the mechanical properties of the skin has been developed. This device, based on indentation and static friction tests, also allows to characterize the skin in vivo and reconstructed DEs in a wide range of light contact forces, stress and strain. This original bio-tribometer shows the ability to assess the skin elasticity and friction force in a wide range of light normal load (0.5-2 g) and low contact pressure (0.5-2 kPa). The results obtained by this approach show identical values of the Young's modulus E(*) and the shear modulus G(*) of six DEs obtained from a 62-year-old subject (E(*)=8.5+/-1.74 kPa and G(*)=3.3+/-0.46 kPa) and in vivo total skin of 20 subjects aged 55 to 70 years (E(*)=8.3+/-2.1 kPa, G(*)=2.8+/-0.8 kpa).

Physical, mechanical and electrochemical characterization of all-perovskite intermediate temperature solid oxide fuel cells

Science.gov (United States)

Mohammadi, Alidad

Strontium- and magnesium-doped lanthanum gallate (LSGM) has been considered as a promising electrolyte for solid oxide fuel cell (SOFC) systems in recent years due to its high ionic conductivity and chemical stability over a wide range of oxygen partial pressures and temperatures. This research describes synthesis, physical and mechanical behavior, electrochemical properties, phase evolution, and microstructure of components of an all-perovskite anode-supported intermediate temperature solid oxide fuel cell (ITSOFC), based on porous La 0.75Sr0.25Cr0.5Mn0.5O3 (LSCM) anode, La0.8Sr0.2Ga0.8Mg0.2O 2.8 (LSGM) electrolyte, and porous La0.6Sr0.4Fe 0.8Co0.2O3 (LSCF) cathode. The phase evolution of synthesized LSGM and LSCM powders has been investigated, and it has been confirmed that there is no reaction between LSGM and LSCM at sintering temperature. Using different amounts of poreformers and binders as well as controlling firing temperature, porosity of the anode was optimized while still retaining good mechanical integrity. The effect of cell operation conditions under dry hydrogen fuel on the SOFC open circuit voltage (OCV) and cell performance were also investigated. Characterization study of the synthesized LSGM indicates that sintering at 1500°C obtains higher electrical conductivity compared to the currently published results, while conductivity of pellets sintered at 1400°C and 1450°C would be slightly lower. The effect of sintering temperature on bulk and grain boundary resistivities was also discussed. The mechanical properties, such as hardness, Young's modulus, fracture toughness and modulus of rupture of the electrolyte were determined and correlated with scanning electron microscopy (SEM) morphological characterization. Linear thermal expansion and thermal expansion coefficient of LSGM were also measured.

Estimation of Mechanical Signals in Induction Motors using the Recursive Prediction Error Method

DEFF Research Database (Denmark)

Børsting, H.; Knudsen, Morten; Rasmussen, Henrik

1993-01-01

Sensor feedback of mechanical quantities for control applications in induction motors is troublesome and relative expensive. In this paper a recursive prediction error (RPE) method has successfully been used to estimate the angular rotor speed ........Sensor feedback of mechanical quantities for control applications in induction motors is troublesome and relative expensive. In this paper a recursive prediction error (RPE) method has successfully been used to estimate the angular rotor speed .....

A multi-method approach toward de novo glycan characterization: a Man-5 case study.

Science.gov (United States)

Prien, Justin M; Prater, Bradley D; Cockrill, Steven L

2010-05-01

Regulatory agencies' expectations for biotherapeutic approval are becoming more stringent with regard to product characterization, where minor species as low as 0.1% of a given profile are typically identified. The mission of this manuscript is to demonstrate a multi-method approach toward de novo glycan characterization and quantitation, including minor species at or approaching the 0.1% benchmark. Recently, unexpected isomers of the Man(5)GlcNAc(2) (M(5)) were reported (Prien JM, Ashline DJ, Lapadula AJ, Zhang H, Reinhold VN. 2009. The high mannose glycans from bovine ribonuclease B isomer characterization by ion trap mass spectrometry (MS). J Am Soc Mass Spectrom. 20:539-556). In the current study, quantitative analysis of these isomers found in commercial M(5) standard demonstrated that they are in low abundance (2-aminobenzoic acid to detect and chromatographically resolve multiple M(5) isomers in bovine ribonuclease B. With this multi-method approach, we have the capabilities to comprehensively characterize a biotherapeutic's glycan array in a de novo manner, including structural isomers at >/=0.1% of the total chromatographic peak area.

Evaluation of lung and chest wall mechanics during anaesthesia using the PEEP-step method.

Science.gov (United States)

Persson, P; Stenqvist, O; Lundin, S

2018-04-01

Postoperative pulmonary complications are common. Between patients there are differences in lung and chest wall mechanics. Individualised mechanical ventilation based on measurement of transpulmonary pressures would be a step forward. A previously described method evaluates lung and chest wall mechanics from a change of ΔPEEP and calculation of change in end-expiratory lung volume (ΔEELV). The aim of the present study was to validate this PEEP-step method (PSM) during general anaesthesia by comparing it with the conventional method using oesophageal pressure (PES) measurements. In 24 lung healthy subjects (BMI 18.5-32), three different sizes of PEEP steps were performed during general anaesthesia and ΔEELVs were calculated. Transpulmonary driving pressure (ΔPL) for a tidal volume equal to each ΔEELV was measured using PES measurements and compared to ΔPEEP with limits of agreement and intraclass correlation coefficients (ICC). ΔPL calculated with both methods was compared with a Bland-Altman plot. Mean differences between ΔPEEP and ΔPL were mechanical properties among the lung healthy patients stresses the need for individualised ventilator settings based on measurements of lung and chest wall mechanics. The agreement between ΔPLs measured by the two methods during general anaesthesia suggests the use of the non-invasive PSM in this patient population. NCT 02830516. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Insights into the Thiamine Diphosphate Enzyme Activation Mechanism: Computational Model for Transketolase Using a Quantum Mechanical/Molecular Mechanical Method.

Science.gov (United States)

Nauton, Lionel; Hélaine, Virgil; Théry, Vincent; Hecquet, Laurence

2016-04-12

We propose the first computational model for transketolase (TK), a thiamine diphosphate (ThDP)-dependent enzyme, using a quantum mechanical/molecular mechanical method on the basis of crystallographic TK structures from yeast and Escherichia coli, together with experimental kinetic data reported in the literature with wild-type and mutant TK. This model allowed us to define a new route for ThDP activation in the enzyme environment. We evidenced a strong interaction between ThDP and Glu418B of the TK active site, itself stabilized by Glu162A. The crucial point highlighted here is that deprotonation of ThDP C2 is not performed by ThDP N4' as reported in the literature, but by His481B, involving a HOH688A molecule bridge. Thus, ThDP N4' is converted from an amino form to an iminium form, ensuring the stabilization of the C2 carbanion or carbene. Finally, ThDP activation proceeds via an intermolecular process and not by an intramolecular one as reported in the literature. More generally, this proposed ThDP activation mechanism can be applied to some other ThDP-dependent enzymes and used to define the entire TK mechanism with donor and acceptor substrates more accurately.

Methods for the physical characterization and quantification of extracellular vesicles in biological samples.

Science.gov (United States)

Rupert, Déborah L M; Claudio, Virginia; Lässer, Cecilia; Bally, Marta

2017-01-01

Our body fluids contain a multitude of cell-derived vesicles, secreted by most cell types, commonly referred to as extracellular vesicles. They have attracted considerable attention for their function as intercellular communication vehicles in a broad range of physiological processes and pathological conditions. Extracellular vesicles and especially the smallest type, exosomes, have also generated a lot of excitement in view of their potential as disease biomarkers or as carriers for drug delivery. In this context, state-of-the-art techniques capable of comprehensively characterizing vesicles in biological fluids are urgently needed. This review presents the arsenal of techniques available for quantification and characterization of physical properties of extracellular vesicles, summarizes their working principles, discusses their advantages and limitations and further illustrates their implementation in extracellular vesicle research. The small size and physicochemical heterogeneity of extracellular vesicles make their physical characterization and quantification an extremely challenging task. Currently, structure, size, buoyant density, optical properties and zeta potential have most commonly been studied. The concentration of vesicles in suspension can be expressed in terms of biomolecular or particle content depending on the method at hand. In addition, common quantification methods may either provide a direct quantitative measurement of vesicle concentration or solely allow for relative comparison between samples. The combination of complementary methods capable of detecting, characterizing and quantifying extracellular vesicles at a single particle level promises to provide new exciting insights into their modes of action and to reveal the existence of vesicle subpopulations fulfilling key biological tasks. Copyright © 2016 Elsevier B.V. All rights reserved.

Development of an evaluation method for fracture mechanical tests on small samples based on a cohesive zone model

International Nuclear Information System (INIS)

Mahler, Michael

2016-01-01

The safety and reliability of nuclear power plants of the fourth generation is an important issue. It is based on a reliable interpretation of the components for which, among other fracture mechanical material properties are required. The existing irradiation in the power plants significantly affects the material properties which therefore need to be determined on irradiated material. Often only small amounts of irradiated material are available for characterization. In that case it is not possible to manufacture sufficiently large specimens, which are necessary for fracture mechanical testing in agreement with the standard. Small specimens must be used. From this follows the idea of this study, in which the fracture toughness can be predicted with the developed method based on tests of small specimens. For this purpose, the fracture process including the crack growth is described with a continuum mechanical approach using the finite element method and the cohesive zone model. The experiments on small specimens are used for parameter identification of the cohesive zone model. The two parameters of the cohesive zone model are determined by tensile tests on notched specimens (cohesive stress) and by parameter fitting to the fracture behavior of smalls specimens (cohesive energy). To account the different triaxialities of the specimens, the cohesive stress is used depending on the triaxiality. After parameter identification a large specimen can be simulated with the cohesive zone parameters derived from small specimens. The predicted fracture toughness of this big specimen fulfills the size requirements in the standard (ASTM E1820 or ASTM E399) in contrast to the small specimen. This method can be used for ductile and brittle material behavior and was validated in this work. In summary, this method offers the possibility to determine the fracture toughness indirectly based on small specimen testing. Main advantage is the low required specimen volume. Thereby massively

Evaluating the reliability of multi-body mechanisms: A method considering the uncertainties of dynamic performance

International Nuclear Information System (INIS)

Wu, Jianing; Yan, Shaoze; Zuo, Ming J.

2016-01-01

Mechanism reliability is defined as the ability of a certain mechanism to maintain output accuracy under specified conditions. Mechanism reliability is generally assessed by the classical direct probability method (DPM) derived from the first order second moment (FOSM) method. The DPM relies strongly on the analytical form of the dynamic solution so it is not applicable to multi-body mechanisms that have only numerical solutions. In this paper, an indirect probability model (IPM) is proposed for mechanism reliability evaluation of multi-body mechanisms. IPM combines the dynamic equation, degradation function and Kaplan–Meier estimator to evaluate mechanism reliability comprehensively. Furthermore, to reduce the amount of computation in practical applications, the IPM is simplified into the indirect probability step model (IPSM). A case study of a crank–slider mechanism with clearance is investigated. Results show that relative errors between the theoretical and experimental results of mechanism reliability are less than 5%, demonstrating the effectiveness of the proposed method. - Highlights: • An indirect probability model (IPM) is proposed for mechanism reliability evaluation. • The dynamic equation, degradation function and Kaplan–Meier estimator are used. • Then the simplified form of indirect probability model is proposed. • The experimental results agree well with the predicted results.

Gelatinized and nongelatinized corn starch/ poly(epsilon-caprolactone blends: characterization by rheological, mechanical and morphological properties

Directory of Open Access Journals (Sweden)

Derval S. Rosa

2004-09-01

Full Text Available Poly(epsilon-caprolactone/corn starch blends containing 25, 50 and 75 wt.% starch were prepared by mechanical processing and characterized by the melt flow index (MFI, tensile test and scanning electron microscopy (SEM. For comparison, starch was used in gelatinized and nongelatinized forms and was also characterized by viscography. The addition of starch to poly(epsilon-caprolactone reduced the MFI values, the tensile strength and the elongation at break, whereas the modulus increased. The reductions in the MFI and tensile properties were most evident when gelatinized starch was used. Viscography and SEM showed that starch was well gelatinized by the gelatinization process. Blends containing nongelatinized starch showed a good dispersion of starch but poor interfacial interactions.

Mechanical Conversion for High-Throughput TEM Sample Preparation

International Nuclear Information System (INIS)

Kendrick, Anthony B; Moore, Thomas M; Zaykova-Feldman, Lyudmila

2006-01-01

This paper presents a novel method of direct mechanical conversion from lift-out sample to TEM sample holder. The lift-out sample is prepared in the FIB using the in-situ liftout Total Release TM method. The mechanical conversion is conducted using a mechanical press and one of a variety of TEM coupons, including coupons for both top-side and back-side thinning. The press joins a probe tip point with attached TEM sample to the sample coupon and separates the complete assembly as a 3mm diameter TEM grid, compatible with commercially available TEM sample holder rods. This mechanical conversion process lends itself well to the high through-put requirements of in-line process control and to materials characterization labs where instrument utilization and sample security are critically important

Statistical methods and materials characterisation

International Nuclear Information System (INIS)

Wallin, K.R.W.

2010-01-01

Statistics is a wide mathematical area, which covers a myriad of analysis and estimation options, some of which suit special cases better than others. A comprehensive coverage of the whole area of statistics would be an enormous effort and would also be outside the capabilities of this author. Therefore, this does not intend to be a textbook on statistical methods available for general data analysis and decision making. Instead it will highlight a certain special statistical case applicable to mechanical materials characterization. The methods presented here do not in any way rule out other statistical methods by which to analyze mechanical property material data. (orig.)

Information needs for characterization of high-level waste repository sites in six geologic media. Volume 2. Appendices

Energy Technology Data Exchange (ETDEWEB)

NONE

1985-05-01

Volume II contains appendices for the following: (1) remote sensing and surface mapping techniques; (2) subsurface mapping methods for site characterization; (3) gravity technique; (4) audio-frequency magnetotelluric technique; (5) seismic refraction technique; (6) direct-current electrical resistivity method; (7) magnetic technique; (8) seismic reflection technique; (9) seismic crosshole method; (10) mechanical downhole seismic velocity survey method; (11) borehole geophysical logging techniques; (12) drilling and coring methods for precharacterization studies; (13) subsurface drilling methods for site characterization; (14) geomechanical/thermomechanical techniques for precharacterization studies; (15)geomechanical/thermal techniques for site characterization studies; (16) exploratory geochemical techniques for precharacterization studies; (17) geochemical techniques for site characterization; (18) hydrologic techniques for precharacterization studies; (19) hydrologic techniques for site characterization; and (20) seismological techniques.

Information needs for characterization of high-level waste repository sites in six geologic media. Volume 2. Appendices

International Nuclear Information System (INIS)

1985-05-01

Volume II contains appendices for the following: (1) remote sensing and surface mapping techniques; (2) subsurface mapping methods for site characterization; (3) gravity technique; (4) audio-frequency magnetotelluric technique; (5) seismic refraction technique; (6) direct-current electrical resistivity method; (7) magnetic technique; (8) seismic reflection technique; (9) seismic crosshole method; (10) mechanical downhole seismic velocity survey method; (11) borehole geophysical logging techniques; (12) drilling and coring methods for precharacterization studies; (13) subsurface drilling methods for site characterization; (14) geomechanical/thermomechanical techniques for precharacterization studies; (15)geomechanical/thermal techniques for site characterization studies; (16) exploratory geochemical techniques for precharacterization studies; (17) geochemical techniques for site characterization; (18) hydrologic techniques for precharacterization studies; (19) hydrologic techniques for site characterization; and (20) seismological techniques

Characterization of polarization-independent phase modulation method for practical plug and play quantum cryptography

International Nuclear Information System (INIS)

Kwon, Osung; Lee, Min-Soo; Woo, Min Ki; Park, Byung Kwon; Kim, Il Young; Kim, Yong-Su; Han, Sang-Wook; Moon, Sung

2015-01-01

We characterized a polarization-independent phase modulation method, called double phase modulation, for a practical plug and play quantum key distribution (QKD) system. Following investigation of theoretical backgrounds, we applied the method to the practical QKD system and characterized the performance through comparing single phase modulation (SPM) and double phase modulation. Consequently, we obtained repeatable and accurate phase modulation confirmed by high visibility single photon interference even for input signals with arbitrary polarization. Further, the results show that only 80% of the bias voltage required in the case of single phase modulation is needed to obtain the target amount of phase modulation. (paper)

Mechanical tests imaging on metallic matrix composites. Experimental contribution to homogenization methods validation and identification of phase-related mechanical properties

International Nuclear Information System (INIS)

Quoc-Thang Vo

2013-01-01

This work is focused on a matrix/inclusion metal composite. A simple method is proposed to evaluate the elastic properties of one phase while the properties of the other phase are assumed to be known. The method is based on both an inverse homogenization scheme and mechanical field's measurements by 2D digital image correlation. The originality of the approach rests on the scale studied, i.e. the microstructure scale of material: the characteristic size of the inclusions is about few tens of microns. The evaluation is performed on standard uniaxial tensile tests associated with a long-distance microscope. It allows observation of the surface of a specimen on the microstructure scale during the mechanical stress. First, the accuracy of the method is estimated on 'perfect' mechanical fields coming from numerical simulations for four microstructures: elastic or porous single inclusions having either spherical or cylindrical shape. Second, this accuracy is estimated on real mechanical field for two simple microstructures: an elasto-plastic metallic matrix containing a single cylindrical micro void or four cylindrical micro voids arranged in a square pattern. Third, the method is used to evaluate elastic properties of αZr inclusions with arbitrary shape in an oxidized Zircaloy-4 sample of the fuel cladding of a pressurized water reactor after an accident loss of coolant accident (LOCA). In all this study, the phases are assumed to have isotropic properties. (author) [fr

Plant management in natural areas: balancing chemical, mechanical, and cultural control methods