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Sample records for unique thermal mechanical

  1. Unique nuclear thermal rocket engine

    Energy Technology Data Exchange (ETDEWEB)

    Culver, D.W. (Aerojet Propulsion Division, P.O. Box 13222, Sacramento, California 95813-6000 (United States)); Rochow, R. (Babcock Wilcox Space Nuclear Systems, P.O. Box 11165, Lynchburg, Virginia 24506-1165 (United States))

    1993-01-15

    Earlier this year Aerojet Propulsion Division (APD) introduced a new, advanced nuclear thermal rocket engine (NTRE) concept intended for manned missions to the moon and to Mars. This NTRE promises to be both shorter and lighter in weight than conventionally designed engines, because its forward flowing reactor is located within an expansion-deflection (E-D) rocket nozzle. The concept has matured during the year, and this paper discusses a nearer term version that resolves four open issues identified in the initial concept: (1)Reactor design and cooling scheme simplification while retaining a high pressure power balance option; (2)Eliminate need for a new, uncooled nozzle throat material suitable for long life application; (3)Practical provision for reactor power control; and (4)Use near term, long life turbopumps.

  2. Unique nuclear thermal rocket engine

    Science.gov (United States)

    Culver, Donald W.; Rochow, Richard

    1993-06-01

    In January, 1992, a new, advanced nuclear thermal rocket engine (NTRE) concept intended for manned missions to the moon and to Mars was introduced (Culver, 1992). This NTRE promises to be both shorter and lighter in weight than conventionally designed engines, because its forward flowing reactor is located within an expansion-deflection rocket nozzle. The concept has matured during the year, and this paper discusses a nearer term version that resolves four open issues identified in the initial concept: (1) the reactor design and cooling scheme simplification while retaining a high pressure power balance option; (2) elimination need for a new, uncooled nozzle throat material suitable for long life application; (3) a practical provision for reactor power control; and (4) use of near-term, long-life turbopumps.

  3. Instrument Thermal Test Bed - A unique two phase test facility

    Science.gov (United States)

    Swanson, Theodore; Didion, Jeffrey

    1991-01-01

    The Instrument Thermal Test Bed (ITTB) is a modular, large-scale test facility which provides a medium for ground testing and flight qualification of spacecraft thermal control components and system configurations. The initial 'shade-down' operations are discussed herein. Operational parameters and performance characteristics were determined and quantified on a preliminary basis. The ITTB was successfully operated at evaporator power loads ranging from 600 W to 9600 W as well as in both capillary pumped and series hybrid pumped modes.

  4. Building unique surface structure on aramid fibers through a green layer-by-layer self-assembly technique to develop new high performance fibers with greatly improved surface activity, thermal resistance, mechanical properties and UV resistance

    Science.gov (United States)

    Zhou, Lifang; Yuan, Li; Guan, Qingbao; Gu, Aijuan; Liang, Guozheng

    2017-07-01

    Combining green preparation and high performance is becoming the direction of sustainable development of materials. How to simultaneously overcome the two bottlenecks (poor surface activity and UV resistance) of aramid fibers (AFs) while improving thermal and mechanical properties through a green process is still an interesting issue with big challenge. Herein, new AFs (BL-AFs) were prepared by alternately self-assembling SiO2 and MgAlFe layered double hydroxide (LDH) on surfaces of AFs, successively, through a green layer-by-layer (LBL) self-assembly technique without using high temperature and organic solvent. The structures and properties of BL-AFs were systematically studied, which are controllable by adjusting the number of self-assembly cycle. The new fibers with three or more self-assembly cycles have remarkably improved surface activity, thermal resistance, mechanical properties and UV resistance compared with AFs. Typically, with three self-assembly cycles, the initial degradation temperature and char yield of the new fiber (3BL-AF) are as high as 552.9 °C and 81.2%, about 92 °C and 25.2% higher than those of AF, respectively; after 168 h-UV irradiation, the retention of tensile performances of 3BL-AF fiber is as high as 91-95%, about 29-14% higher than that of AF, showing the best overall performances among all modified AFs prepared using a green technique reported so far. The origin behind the attractive performances of BL-AFs is revealed through correlating with structures of original and modified fibers. The excellent comprehensive properties of BL-AFs demonstrate that the green method provided in this study is facile and effective to completely solve the bottlenecks of aramid fibers, and developing higher performance organic fibers.

  5. Unique microstructure and excellent mechanical properties of ADI

    Directory of Open Access Journals (Sweden)

    Jincheng Liu

    2006-11-01

    Full Text Available Amongst the cast iron family, ADI has a unique microstructure and an excellent, optimised combination of mechanical properties. The main microstructure of ADI is ausferrite, which is a mixture ofextremely fine acicular ferrite and stable, high carbon austenite. There are two types of austenite in ADI:(1 the coarser and more equiaxed blocks of austenite between non-parallel acicular structures, which exist mainly in the last solidified area, and (2 the thin films of ustenite between the individual ferriteplatelets in the acicular structure. It is this unique microstructure, which gives ADI its excellent static and dynamic properties, and good low temperature impact toughness. The effect of microstructure on the mechanical properties is explained in more detail by examining the microstructure at the atomic scale. Considering the nanometer grain sizes, the unique microstructure, the excellent mechanical properties,good castability, (which enables near net shape components to be produced economically and in large volumes, and the fact that it can be 100% recycled, it is not overemphasized to call ADI a high-tech,nanometer and “green” material. ADI still has the potential to be further improved and its production and the number of applications for ADI will continue to grow, driven by the resultant cost savings over alternative materials.

  6. Unique microstructure and excellent mechanical properties of ADI

    Institute of Scientific and Technical Information of China (English)

    Jincheng Liu

    2006-01-01

    Amongst the cast iron family, ADI has a unique microstructure and an excellent, optimised combination of mechanical properties. The main microstructure of ADI is ausferrite, which is a mixture of extremely fine acicular ferrite and stable, high carbon austenite. There are two types of austenite in ADI:(1) the coarser and more equiaxed blocks of austenite between non-parallel acicular structures, which exist mainly in the last solidified area, and (2) the thin films of austenite between the individual ferrite platelets in the acicular structure. It is this unique microstructure, which gives ADI its excellent static and dynamic properties, and good low temperature impact toughness. The effect of microstructure on the mechanical properties is explained in more detail by examining the microstructure at the atomic scale.Considering the nanometer grain sizes the unique microstructure, the excellent mechanical properties,good castability, (which enables near net shape components to be produced economically and in large volumes), and the fact that it can be 100% recycled, it is not overemphasized to call ADI a high-tech,nanometer and "green" material. ADI still has the potential to be further improved and its production and the number of applications for ADI will continue to grow, driven by the resultant cost savings over altemative materials.

  7. Solar mechanics thermal response capabilities.

    Energy Technology Data Exchange (ETDEWEB)

    Dobranich, Dean D.

    2009-07-01

    In many applications, the thermal response of structures exposed to solar heat loads is of interest. Solar mechanics governing equations were developed and integrated with the Calore thermal response code via user subroutines to provide this computational simulation capability. Solar heat loads are estimated based on the latitude and day of the year. Vector algebra is used to determine the solar loading on each face of a finite element model based on its orientation relative to the sun as the earth rotates. Atmospheric attenuation is accounted for as the optical path length varies from sunrise to sunset. Both direct and diffuse components of solar flux are calculated. In addition, shadowing of structures by other structures can be accounted for. User subroutines were also developed to provide convective and radiative boundary conditions for the diurnal variations in air temperature and effective sky temperature. These temperature boundary conditions are based on available local weather data and depend on latitude and day of the year, consistent with the solar mechanics formulation. These user subroutines, coupled with the Calore three-dimensional thermal response code, provide a complete package for addressing complex thermal problems involving solar heating. The governing equations are documented in sufficient detail to facilitate implementation into other heat transfer codes. Suggestions for improvements to the approach are offered.

  8. Transfer orbit stage mechanisms thermal vacuum test

    Science.gov (United States)

    Oleary, Scott T.

    1990-01-01

    A systems level mechanisms test was conducted on the Orbital Sciences Corp.'s Transfer Orbit Stage (TOS). The TOS is a unique partially reusable transfer vehicle which will boost a satellite into its operational orbit from the Space Shuttle's cargo bay. The mechanical cradle and tilt assemblies will return to earth with the Space Shuttle while the Solid Rocket Motor (SRM) and avionics package are expended. A mechanisms test was performed on the forward cradle and aft tilting assemblies of the TOS under thermal vacuum conditions. Actuating these assemblies under a 1 g environment and thermal vacuum conditions proved to be a complex task. Pneumatic test fixturing was used to lift the forward cradle, and tilt the SRM, and avionics package. Clinometers, linear voltage displacement transducers, and load cells were used in the thermal vacuum chamber to measure the performance and characteristics of the TOS mechanism assembly. Incorporation of the instrumentation and pneumatic system into the test setup was not routine since pneumatic actuation of flight hardware had not been previously performed in the facility. The methods used are presented along with the problems experienced during the design, setup and test phases.

  9. Unique mechanism of chance fracture in a young adult male.

    Science.gov (United States)

    Birch, Aaron; Walsh, Ryan; Devita, Diane

    2013-03-01

    Since the first description of the Chance fracture in 1948, there have been few case reports of unique mechanisms causing this classical flexion-extension injury to the spine in motor vehicle accidents, sports injury, and falls. To our knowledge, this injury has not been reported from a fall with the mechanistic forces acting laterally on the spine and with spinal support in place. We present a 21-year-old male who slid down a flight of stairs onto his side wearing a heavy mountaineering style backpack, subsequently sustaining a Chance fracture of his first lumbar vertebrae.

  10. NASA Invention of the year Award - 2004. The revolutionary unique braided carbon-fiber thermal barr

    Science.gov (United States)

    2005-01-01

    NASA Invention of the year Award - 2004. The revolutionary unique braided carbon-fiber thermal barrier is designed to with stand the extreme temperature environments in current and future solid rocket motors with application to industrial equipment

  11. Growth Mechanism of a Unique Hierarchical Vaterite Structure

    Science.gov (United States)

    Ma, Guobin; Xu, Yifei; Wang, Mu

    2013-03-01

    Calcium carbonate is one of the most significant minerals in nature as well as in biogenic sources. Calcium carbonate occurs naturally in three crystalline polymorphs, i.e., calcite, aragonite, and vaterite. Although it has been attracted much research attention to understanding of the formation mechanisms of the material, the properties of the vaterite polymorph is not well known. Here we report synthesis and formation mechanism of a unique hierarchical structure of vaterite. The material is grown by a controlled diffusion method. The structure possesses a core and an outer part. The core is convex lens-like and is formed by vaterite nanocrystals that have small misorientations. The outer part is separated into six garlic clove-like segments. Each segment possesses piles of plate-like vaterite crystals, and the orientations of the plates continuously change from pile to pile. Based on real-time experimental results and the structural analysis, a growth mechanism is presented. Work supported by NSFC (Grant No. 51172104) and MOST of China (Grant No. 2101CB630705)

  12. Proposition of Unique Pumping System with Counter-Rotating Mechanism

    Directory of Open Access Journals (Sweden)

    Toshiaki Kanemoto

    2004-01-01

    Full Text Available Turbo-pumps have weak points, such as when the pumping operation becomes unstable in the rising portion of the head characteristics and/or the cavitation occurs under the intolerably low suction head. To overcome both weak points simultaneously, this article proposes a unique pumping system with counter-rotating mechanism, which consists of two stage impellers and a peculiar motor with double rotors. The front and the rear impellers are driven by the inner and the outer rotors of the motor, respectively, keeping the relative rotational speed constant and counter-balancing the rotational torque. Such driving conditions not only smartly improve the unstable performance at lower discharge, but also suppress the cavitation at higher discharge, in the optimum cooperation with the impeller works and the rotor outputs.

  13. Experimental thermal mechanics of deployable boom structures

    Science.gov (United States)

    Predmore, R.

    1972-01-01

    An apparatus was developed for thermal distortion measurements on deployable boom structures. The calibration procedure and thermal static bending plus twist measurements are considered. The thermal mechanics test facility is described. A table is presented for several examples of spacecraft applications of thermal static distortion measurements on 3-m deployable booms.

  14. A THERMAL PULSE SHAPER MECHANISM.

    Science.gov (United States)

    A shaped pulse of intense thermal radiation, corresponding to the pulses from nuclear weapons, is obtained by the output of a QM carbon arc. A flywheel driven by a DC motor actuated a venetian blind shutter placed between a mirror and the target to control the flux. The combination produced reasonably good simulation and reproduction of the generalized field pulse.

  15. Fracture mechanism of a thermal barrier coating

    Science.gov (United States)

    Samoilenko, V. M.; Ravilov, R. G.; Drevnyak, V. V.; Petrova, M. A.

    2016-06-01

    The fracture mechanism of the thermal barrier coating of gas turbine blades is studied. The causes of the fracture of the ceramic layer are discussed and the possible ways to increase the fatigue life of the thermal barrier coating are considered.

  16. Waste energy harvesting mechanical and thermal energies

    CERN Document Server

    Ling Bing, Kong; Hng, Huey Hoon; Boey, Freddy; Zhang, Tianshu

    2014-01-01

    Waste Energy Harvesting overviews the latest progress in waste energy harvesting technologies, with specific focusing on waste thermal mechanical energies. Thermal energy harvesting technologies include thermoelectric effect, storage through phase change materials and pyroelectric effect. Waste mechanical energy harvesting technologies include piezoelectric (ferroelectric) effect with ferroelectric materials and nanogenerators. The book aims to strengthen the syllabus in energy, materials and physics and is well suitable for students and professionals in the fields.

  17. Combining several thermal indices to generate a unique heat comfort assessment methodology

    Directory of Open Access Journals (Sweden)

    Wissam EL Hachem

    2015-11-01

    Full Text Available Purpose: The proposed methodology hopes to provide a systematic multi-disciplinary approach to assess the thermal environment while minimizing unneeded efforts. Design/methodology/approach: Different factors affect the perception of the human thermal experience: metabolic rate (biology, surrounding temperatures (heat balance and environmental factors and cognitive treatment (physiology.This paper proposes a combination of different multidisciplinary variables to generate a unique heat comfort assessment methodology. The variables at stake are physiological, biological, and environmental. Our own heat analysis is thoroughly presented and all relevant equations are described. Findings: Most companies are oblivious about potential dangers of heat stress accidents and thus about methods to monitor and prevent them. This methodology enables the company or the concerned individual to conduct a preliminary assessment with minimal wasted resources and time in unnecessary steps whilst providing a guideline for a detailed study with minimal error rates if needed. More so, thermal comfort is an integral part of sound ergonomics practices, which in turn are decisive for the success of any lean six sigma initiative. Research limitations/implications: This methodology requires several full implementations to finalize its design. Originality/value: Most used heat comfort models are inherently uncertain and tiresome to apply. An extensive literature review confirms the need for a uniform assessment methodology that combines the different thermal comfort models such as the Fanger comfort model (PMV, PPD and WGBT since high error rates coupled with tiresome calculations often hinder the thermal assessment process.

  18. Unique Mechanism of Chance Fracture in a Young Adult Male

    Directory of Open Access Journals (Sweden)

    Aaron Birch

    2013-03-01

    Full Text Available Since the first description of the Chance fracture in 1948, there have been few case reports ofunique mechanisms causing this classical flexion-extension injury to the spine in motor vehicleaccidents, sports injury, and falls. To our knowledge, this injury has not been reported from a fall withthe mechanistic forces acting laterally on the spine and with spinal support in place. We present a21-year-old male who slid down a flight of stairs onto his side wearing a heavy mountaineering stylebackpack, subsequently sustaining a Chance fracture of his first lumbar vertebrae.

  19. Gelled Complex Fluids: Combining Unique Structures with Mechanical Stability.

    Science.gov (United States)

    Stubenrauch, Cosima; Gießelmann, Frank

    2016-03-01

    Gelled complex fluids are soft materials in which the microstructure of the complex fluid is combined with the mechanical stability of a gel. To obtain a gelled complex fluid one either adds a gelator to a complex fluid or replaces the solvent in a gel by a complex fluid. The most prominent example of a "natural" gelled complex fluid is the cell. There are various strategies by which one can form a gelled complex fluid; one such strategy is orthogonal self-assembly, that is, the independent but simultaneous formation of two coexisting self-assembled structures within one system. The aim of this Review is to describe the structure and potential applications of various man-made gelled complex fluids and to clarify whether or not the respective system is formed by orthogonal self-assembly.

  20. Design and Preparation of a Unique Segregated Double Network with Excellent Thermal Conductive Property.

    Science.gov (United States)

    Wu, Kai; Lei, Chuxin; Huang, Rui; Yang, Weixing; Chai, Songgang; Geng, Chengzhen; Chen, Feng; Fu, Qiang

    2017-03-01

    It is still a challenge to fabricate polymer-based composites with excellent thermal conductive property because of the well-known difficulties such as insufficient conductive pathways and inefficient filler-filler contact. To address this issue, a synergistic segregated double network by using two fillers with different dimensions has been designed and prepared by taking graphene nanoplates (GNPs) and multiwalled carbon nanotubes (MWCNT) in polystyrene for example. In this structure, GNPs form the segregated network to largely increase the filler-filler contact areas while MWCNT are embedded within the network to improve the network-density. The segregated network and the randomly dispersed hybrid network by using GNPs and MWCNT together were also prepared for comparison. It was found that the thermal conductivity of segregated double network can achieve almost 1.8-fold as high as that of the randomly dispersed hybrid network, and 2.2-fold as that of the segregated network. Meanwhile, much higher synergistic efficiency (f) of 2 can be obtained, even greater than that of other synergistic systems reported previously. The excellent thermal conductive property and higher f are ascribed to the unique effect of segregated double network: (1) extensive GNPs-GNPs contact areas via overlapped interconnections within segregated GNPs network; (2) efficient synergistic effect between MWCNT network and GNPs network based on bridge effect as well as increasing the network-density.

  1. Thermal integrity in mechanics and engineering

    CERN Document Server

    Shorr, Boris F

    2015-01-01

    The book is targeted at engineers, university lecturers, postgraduates, and final year undergraduate students involved in computational modelling and experimental and theoretical analysis of the high-temperature behavior of engineering structures. It will also be of interest to researchers developing the thermal strength theory as a branch of continuum mechanics. Thermal integrity is a multidisciplinary field combining the expertise of mechanical engineers, material scientists and applied mathematicians, each approaching the problem from their specific viewpoint. This monograph draws on the research of a broad scientific community including the author’s contribution. The scope of thermal strength analysis was considerably extended thanks to modern computers and the implementation of FEM codes. However, the author believes that some material models adopted in the advanced high-performance software, are not sufficiently justificated due to lack of easy-to-follow books on the theoretical and experimental aspec...

  2. Biopolymer elasticity: Mechanics and thermal fluctuations.

    Science.gov (United States)

    Sinha, Supurna; Samuel, Joseph

    2012-04-01

    We present an analytical study of the role of thermal fluctuations in shaping molecular elastic properties of semiflexible polymers. Our study interpolates between mechanics and statistical mechanics in a controlled way and shows how thermal fluctuations modify the elastic properties of biopolymers. We present a study of the minimum-energy configurations with explicit expressions for their energy and writhe and plots of the extension versus link for these configurations and a study of fluctuations around the local minima of energy and approximate analytical formulas for the free energy of stretched twisted polymers. The central result of our study is a closed-form expression for the leading thermal fluctuation correction to the free energy around the nonperturbative writhing family solution for the configuration of a biopolymer. From the derived formulas, the predictions of the wormlike chain model for molecular elasticity can be worked out for a comparison against numerical simulations and experiments.

  3. Thermal, chemical, and mechanical cookoff modeling

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, M.L.; Baer, M.R.; Gross, R.J.

    1994-08-01

    A Thermally Reactive, Elastic-plastic eXplosive code, TREX, has been developed to analyze coupled thermal, chemical and mechanical effects associated with cookoff simulation of confined or unconfined energetic materials. In confined systems, pressure buildup precedes thermal runaway, and unconfined energetic material expands to relieve high stress. The model was developed based on nucleation, decomposition chemistry, and elastic/plastic mechanical behavior of a material with a distribution of internal defects represented as clusters of spherical inclusions. A local force balance, with mass continuity constraints, forms the basis of the model requiring input of temperature and reacted gas fraction. This constitutive material model has been incorporated into a quasistatic mechanics code SANTOS as a material module which predicts stress history associated with a given strain history. The thermal-chemical solver XCHEM has been coupled to SANTOS to provide temperature and reacted gas fraction. Predicted spatial history variables include temperature, chemical species, solid/gas pressure, solid/gas density, local yield stress, and gas volume fraction. One-Dimensional Time to explosion (ODTX) experiments for TATB and PBX 9404 (HMX and NC) are simulated using global multistep kinetic mechanisms and the reactive elastic-plastic constitutive model. Pressure explosions, rather than thermal runaway, result in modeling slow cookoff experiments of confined conventional energetic materials such as TATB. For PBX 9404, pressure explosions also occur at fast cookoff conditions because of low temperature reactions of nitrocellulose resulting in substantial pressurization. A demonstrative calculation is also presented for reactive heat flow in a hollow, propellant-filled, stainless steel cylinder, representing a rocket motor. This example simulation show

  4. High thermal stability and unique trimer formation of cytochrome c' from thermophilic Hydrogenophilus thermoluteolus.

    Science.gov (United States)

    Fujii, Sotaro; Masanari, Misa; Inoue, Hiroki; Yamanaka, Masaru; Wakai, Satoshi; Nishihara, Hirofumi; Sambongi, Yoshihiro

    2013-01-01

    Sequence analysis indicated that thermophilic Hydrogenophilus thermoluteolus cytochrome c' (PHCP) and its mesophilic homolog, Allochromatium vinosum cytochrome c' (AVCP), closely resemble each other in a phylogenetic tree of the cytochrome c' family, with 55% sequence identity. The denaturation temperature of PHCP was 87 °C, 35 °C higher than that of AVCP. Furthermore, PHCP exhibited a larger enthalpy change value during its thermal denaturation than AVCP. While AVCP was dimeric, as observed previously, PHCP was trimeric, and this was the first observation as a cytochrome c'. Dissociation of trimeric PHCP and its protein denaturation reversibly occurred at the same time in a two-state transition manner. Therefore, PHCP is enthalpically more stable than AVCP, perhaps due to its unique trimeric form, in addition to the lower number of Gly residues in its putative α-helical regions.

  5. Revised Proof of the Uniqueness Theorem for "No Collapse" Interpretations of Quantum Mechanics

    CERN Document Server

    Bub, J; Goldstein, S; Bub, Jeffrey; Clifton, Rob; Goldstein, Sheldon

    1999-01-01

    We show that the Bub-Clifton uniqueness theorem for 'no collapse' interpretations of quantum mechanics (Studies in the History and Philosophy of Modern Physics 27, 181-219 (1996)) can be proved without the 'weak separability' assumption.

  6. Unique Thermal Stability of Unnatural Hydrophobic Ds Bases in Double-Stranded DNAs.

    Science.gov (United States)

    Kimoto, Michiko; Hirao, Ichiro

    2017-07-26

    Genetic alphabet expansion technology, the introduction of unnatural bases or base pairs into replicable DNA, has rapidly advanced as a new synthetic biology area. A hydrophobic unnatural base pair between 7-(2-thienyl)imidazo[4,5-b]pyridine (Ds) and 2-nitro-4-propynylpyrrole (Px) exhibited high fidelity as a third base pair in PCR. SELEX methods using the Ds-Px pair enabled high-affinity DNA aptamer generation, and introducing a few Ds bases into DNA aptamers extremely augmented their affinities and selectivities to target proteins. Here, to further scrutinize the functions of this highly hydrophobic Ds base, the thermal stabilities of double-stranded DNAs (dsDNA) containing a noncognate Ds-Ds or G-Ds pair were examined. The thermal stability of the Ds-Ds self-pair was as high as that of the natural G-C pair, and apart from the generally higher stability of the G-C pair than that of the A-T pair, most of the 5'-pyrimidine-Ds-purine-3' sequences, such as CDsA and TDsA, exhibited higher stability than the 5'-purine-Ds-pyrimidine-3' sequences, such as GDsC and ADsC, in dsDNAs. This trait enabled the GC-content-independent control of the thermal stability of the designed dsDNA fragments. The melting temperatures of dsDNA fragments containing the Ds-Ds pair can be predicted from the nearest-neighbor parameters including the Ds base. In addition, the noncognate G-Ds pair can efficiently distinguish its neighboring cognate natural base pairs from noncognate pairs. We demonstrated that real-time PCR using primers containing Ds accurately detected a single-nucleotide mismatch in target DNAs. These unique properties of the Ds base that affect the stabilities of the neighboring base pairs could impart new functions to DNA molecules and technologies.

  7. Thermal integrity in mechanics and engineering

    Energy Technology Data Exchange (ETDEWEB)

    Shorr, Boris F. [Central Institute of Aviation Motors (CIAM), Moscow (Russian Federation)

    2015-07-01

    The book is targeted at engineers, university lecturers, postgraduates, and final year undergraduate students involved in computational modelling and experimental and theoretical analysis of the high-temperature behavior of engineering structures. It will also be of interest to researchers developing the thermal strength theory as a branch of continuum mechanics. Thermal integrity is a multidisciplinary field combining the expertise of mechanical engineers, material scientists and applied mathematicians, each approaching the problem from their specific viewpoint. This monograph draws on the research of a broad scientific community including the author's contribution. The scope of thermal strength analysis was considerably extended thanks to modern computers and the implementation of FEM codes. However, the author believes that some material models adopted in the advanced high-performance software, are not sufficiently justificated due to lack of easy-to-follow books on the theoretical and experimental aspects of thermal integrity. The author endeavors to provide a thorough yet sufficiently simple presentation of the underlying concepts, making the book compelling to a wide audience.

  8. Mechanisms of Polymer Curing and Thermal Degradation

    Science.gov (United States)

    1979-12-01

    for Thermal Polymerization of Bis [4- (Ethynylphenoxy) Phenyl] Sulfone. 52 In the proposed mechanism, .Mj is the biradical , Xi, Xj, Xk, and X’ are...initiation involves the tail-to-tail addition of two monomer units to yield a trans- biradical . Propogation is assumed to occur with equal probability at each...radical site in the biradical ; however, it is conceivable that one of the centers could be deactivated and initiation would result from a monoradical

  9. 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.

  10. Non-Fourier based thermal-mechanical tissue damage prediction for thermal ablation.

    Science.gov (United States)

    Li, Xin; Zhong, Yongmin; Smith, Julian; Gu, Chengfan

    2017-01-02

    Prediction of tissue damage under thermal loads plays important role for thermal ablation planning. A new methodology is presented in this paper by combing non-Fourier bio-heat transfer, constitutive elastic mechanics as well as non-rigid motion of dynamics to predict and analyze thermal distribution, thermal-induced mechanical deformation and thermal-mechanical damage of soft tissues under thermal loads. Simulations and comparison analysis demonstrate that the proposed methodology based on the non-Fourier bio-heat transfer can account for the thermal-induced mechanical behaviors of soft tissues and predict tissue thermal damage more accurately than classical Fourier bio-heat transfer based model.

  11. Relativistic dynamics compels a thermalized Fermi gas to a unique intrinsic parity eigenstate

    CERN Document Server

    Bernardini, Alex E

    2014-01-01

    Dirac equation describes the dynamics of a relativistic spin-1/2 particle regarding its spatial motion and intrinsic degrees of freedom. Here we adopt the point of view that the spinors describe the state of a massive particle carrying two qubits of information: helicity and intrinsic parity. We show that the density matrix for a gas of free fermions, in thermal equilibrium, correlates helicity and intrinsic parity. Our results introduce the basic elements for discussing the spin-parity correlation for a Fermi gas: (1) at the ultra-relativistic domains, when the temperature is quite high, $T > 10^{10}\\ K$, the fermions have no definite intrinsic parity (50% : 50%), which is maximally correlated with the helicity; (2) at very low temperature, $T \\approx 3 \\ K$, a unique parity dominates (conventionally chosen positive), by $10^{20}$ to $1$, while the helicity goes into a mixed state for spin up and down, and the quantum correlation decoheres. For the anti-fermions we get the opposite behavior. In the framework...

  12. Biodegradable compounds: Rheological, mechanical and thermal properties

    Science.gov (United States)

    Nobile, Maria Rossella; Lucia, G.; Santella, M.; Malinconico, M.; Cerruti, P.; Pantani, R.

    2015-12-01

    Recently great attention from industry has been focused on biodegradable polyesters derived from renewable resources. In particular, PLA has attracted great interest due to its high strength and high modulus and a good biocompatibility, however its brittleness and low heat distortion temperature (HDT) restrict its wide application. On the other hand, Poly(butylene succinate) (PBS) is a biodegradable polymer with a low tensile modulus but characterized by a high flexibility, excellent impact strength, good thermal and chemical resistance. In this work the two aliphatic biodegradable polyesters PBS and PLA were selected with the aim to obtain a biodegradable material for the industry of plastic cups and plates. PBS was also blended with a thermoplastic starch. Talc was also added to the compounds because of its low cost and its effectiveness in increasing the modulus and the HDT of polymers. The compounds were obtained by melt compounding in a single screw extruder and the rheological, mechanical and thermal properties were investigated. The properties of the two compounds were compared and it was found that the values of the tensile modulus and elongation at break measured for the PBS/PLA/Talc compound make it interesting for the production of disposable plates and cups. In terms of thermal resistance the compounds have HDTs high enough to contain hot food or beverages. The PLA/PBS/Talc compound can be, then, considered as biodegradable substitute for polystyrene for the production of disposable plates and cups for hot food and beverages.

  13. Mechanical Vibrations of Thermally Actuated Silicon Membranes

    Directory of Open Access Journals (Sweden)

    Lynn Fuller

    2012-03-01

    Full Text Available A thermally-actuated micro-electro-mechanical (MEMS device based on a vibrating silicon membrane has been proposed as a viscosity sensor by the authors. In this paper we analyze the vibration mode of the sensor as it vibrates freely at its natural frequency. Analytical examination is compared to finite element analysis, electrical measurements and the results obtained through real-time dynamic optical surface profilometry. The vertical movement of the membrane due to the applied heat is characterized statically and dynamically. The natural vibration mode is determined to be the (1,1 mode and good correlation is found between the analytical predictions, the simulation analysis, the observed mechanical displacement and the electrical measurements.

  14. HEAVY AND THERMAL OIL RECOVERY PRODUCTION MECHANISMS

    Energy Technology Data Exchange (ETDEWEB)

    Anthony R. Kovscek

    2003-01-01

    This technical progress report describes work performed from October 1 through December 31, 2002 , for the project ''Heavy and Thermal Oil Recovery Production Mechanisms.'' In this project, a broad spectrum of research is undertaken related to thermal and heavy-oil recovery. The research tools and techniques used are varied and span from pore-level imaging of multiphase fluid flow to definition of reservoir-scale features through streamline-based history-matching techniques. During this period, experimental data regarding multidimensional imbibition was analyzed to obtain shape factors appropriate for dual-porosity simulation. It is shown that the usual assumption of constant, time-independent shape factors is incorrect. In other work, we continued to study the mechanisms by which oil is produced from fractured media at high pressure and high temperature. High temperature significantly increased the apparent wettability and affected water relative permeability of cores used in previous experiments. A phenomenological and mechanistic cause for this behavior is sought. Our work in the area of primary production of heavy oil continues with field cores and crude oil. On the topic of reservoir definition, work continued on developing techniques that integrate production history into reservoir models using streamline-based properties.

  15. Pharmaceutical applications of dynamic mechanical thermal analysis.

    Science.gov (United States)

    Jones, David S; Tian, Yiwei; Abu-Diak, Osama; Andrews, Gavin P

    2012-04-01

    The successful development of polymeric drug delivery and biomedical devices requires a comprehensive understanding of the viscoleastic properties of polymers as these have been shown to directly affect clinical efficacy. Dynamic mechanical thermal analysis (DMTA) is an accessible and versatile analytical technique in which an oscillating stress or strain is applied to a sample as a function of oscillatory frequency and temperature. Through cyclic application of a non-destructive stress or strain, a comprehensive understanding of the viscoelastic properties of polymers may be obtained. In this review, we provide a concise overview of the theory of DMTA and the basic instrumental/operating principles. Moreover, the application of DMTA for the characterization of solid pharmaceutical and biomedical systems has been discussed in detail. In particular we have described the potential of DMTA to measure and understand relaxation transitions and miscibility in binary and higher-order systems and describe the more recent applications of the technique for this purpose.

  16. Thermal mechanical analysis of sprag clutches

    Science.gov (United States)

    Mullen, Robert L.; Zab, Ronald Joseph; Kurniawan, Antonius S.

    1992-01-01

    Work done at Case Western Reserve University on the Thermal Mechanical analysis of sprag helicopter clutches is reported. The report is presented in two parts. The first part is a description of a test rig for the measurement of the heat generated by high speed sprag clutch assemblies during cyclic torsional loading. The second part describes a finite element modeling procedure for sliding contact. The test rig provides a cyclic torsional load of 756 inch-pounds at 5000 rpm using a four-square arrangement. The sprag clutch test unit was placed between the high speed pinions of the circulating power loop. The test unit was designed to have replaceable inner ad outer races, which contain the instrumentation to monitor the sprag clutch. The torque loading device was chosen to be a water cooled magnetic clutch, which is controlled either manually or through a computer. In the second part, a Generalized Eulerian-Lagrangian formulation for non-linear dynamic problems is developed for solid materials. This formulation is derived from the basic laws and axioms of continuum mechanics. The novel aspect of this method is that we are able to investigate the physics in the spatial region of interest as material flows through it without having to follow material points. A finite element approximation to the governing equations is developed. Iterative Methods for the solution of the discrete finite element equations are explored. A FORTRAN program to implement this formulation is developed and a number of solutions to problems of sliding contact are presented.

  17. A Unique Electrical Thermal Stimulation System Comparable to Moxibustion of Subcutaneous Tissue

    Directory of Open Access Journals (Sweden)

    Hyoun-Seok Myoung

    2014-01-01

    Full Text Available Moxibustion strengthens immunity and it is an effective treatment modality, but, depending on the material quantity, shape, and composition, the thermal strength and intensity can be difficult to control, which may cause pain or epidermal burns. To overcome these limitations, a heat stimulating system which is able to control the thermal intensity was developed. The temperature distributions on epidermis, at 5 mm and 10 mm of depth, in rabbit femoral tissue were compared between moxibustion and the electric thermal stimulation system. The stimulation system consists of a high radio frequency dielectric heating equipment (2 MHz frequency, maximum power 200 W, isolation probe, isolation plate, negative pressure generator, and a temperature assessment system. The temperature was modulated by controlling the stimulation pulse duty ratio, repetition number, and output. There were 95% and 91% temperature distribution correlations between moxibustion and the thermal stimulus at 5 mm and 10 mm of depth in tissue, respectively. Moreover, the epidermal temperature in thermal stimulation was lower than that in moxibustion. These results showed that heat loss by the electric thermal stimulation system is less than that by the traditional moxibustion method. Furthermore, the proposed electric thermal stimulation did not cause adverse effects, such as suppuration or blisters, and also provided subcutaneous stimulation comparable to moxibustion.

  18. Thermo-Mechanical Characterization of Silicon Carbide-Silicon Carbide Composites at Elevated Temperatures Using a Unique Combustion Facility

    Science.gov (United States)

    2009-09-10

    F THERMO-MECHANICAL CHARACTERIZATION OF SILICON CARBIDE - SILICON CARBIDE COMPOSITES AT ELEVATED...MECHANICAL CTERIZATION OF SILICON CARBIDE -SILIC BIDE COMPOSITES AT LEVATED TEMPER S USING A UNIQUE COMBUSTION FACILITY DISSERTATI N Ted T. Kim...THERMO-MECHANICAL CHARACTERIZATION OF SILICON CARBIDE - SILICON CARBIDE COMPOSITES AT ELEVATED TEMPERATURES USING A UNIQUE COMBUSTION FACILITY

  19. Thermal and mechanical evolution of magma reservoirs

    Science.gov (United States)

    Bachmann, O.; Huber, C.; Dufek, J.

    2012-12-01

    Magmas spend most of their suprasolidus lifespan at high crystallinity. Crystal-rich mushes have a low thermal contrast with the surrounding crust and latent heat buffering is expected to decrease the cooling rate as they approach the solidus. The impact of latent buffering is phase-diagram dependent; massive crystallization over a short temperature interval, occurring near invariant points, can significantly increase the time a given magma spends above the solidus. This latent heat effect is likely to play an important role in the upper crust, as the typical upper crustal compositions (dacite) reach the haplogranite eutectic around 40-60 vol% crystals. As high crystallinity is the most probable state for magmas in the upper crust, the interaction between crystal mushes and hot recharges from below is common. Hence, the thermo-mechanical response of mushes to recharge is a central process in the rheological evolution of these systems. An important feedback following recharge is related to the reduction in density as solid phases melt, leading to the development of in-situ overpressures. The combined effect of melting and overpressurization has a two major consequences for magmatic systems, both commonly observed in the rock record: (1) it increases the likelihood for reactivation of locked crystal mushes, and (2) it enhances the assimilation of stoped blocks in the upper crust.

  20. Unique action mechanisms of tramadol in global cerebral ischemia-induced mechanical allodynia.

    Science.gov (United States)

    Matsuura, Wataru; Kageyama, Erika; Harada, Shinichi; Tokuyama, Shogo

    2016-06-15

    Central poststroke pain is associated with specific somatosensory abnormalities, such as neuropathic pain syndrome. Although central poststroke pain is a serious condition, details pertaining to underlying mechanisms are not well established, making current standard treatments only partially effective. Here, we assessed the effects of tramadol, an analgesic drug mediated by opioid receptors, using a mouse model of global cerebral ischemia. Ischemia was induced by bilateral carotid artery occlusion (30 min) in male ddY mice. Development of hind-paw mechanical allodynia was measured 3 days after bilateral carotid artery occlusion using the von Frey test. Mechanical allodynia was significantly and dose dependently suppressed by intraperitoneal tramadol (10 or 20 mg/kg). These effects, which peaked at 10 min and continued for at least 60 min, were inhibited by naloxone (nonselective opioid receptor antagonist, 1 mg/kg, intraperitoneal). Tramadol antinociception was significantly negated by β-funaltrexamine (selective μ-opioid receptor antagonist, 20 mg/kg, intraperitoneal), but not naltrindole (selective δ-opioid receptor antagonist, 5 mg/kg, intraperitoneal) or nor-binaltorphimine (selective κ-opioid receptor antagonist, 10 mg/kg, intraperitoneal) after 5 min, by β-funaltrexamine and nor-binaltorphimine but not naltrindole after 10 min, and by all selective opioid receptor antagonists at 15 and 30 min after tramadol treatment. These results suggested that antinociception induced by tramadol through various opioid receptors was time dependent. Furthermore, it is possible that the opioid receptors involved in tramadol-induced antinociception change over time with the metabolism of this drug.

  1. Singular characteristics and unique chemical bond activation mechanisms of photocatalytic reactions on plasmonic nanostructures

    Science.gov (United States)

    Christopher, Phillip; Xin, Hongliang; Marimuthu, Andiappan; Linic, Suljo

    2012-12-01

    The field of heterogeneous photocatalysis has almost exclusively focused on semiconductor photocatalysts. Herein, we show that plasmonic metallic nanostructures represent a new family of photocatalysts. We demonstrate that these photocatalysts exhibit fundamentally different behaviour compared with semiconductors. First, we show that photocatalytic reaction rates on excited plasmonic metallic nanostructures exhibit a super-linear power law dependence on light intensity (rate ∝intensityn, with n > 1), at significantly lower intensity than required for super-linear behaviour on extended metal surfaces. We also demonstrate that, in sharp contrast to semiconductor photocatalysts, photocatalytic quantum efficiencies on plasmonic metallic nanostructures increase with light intensity and operating temperature. These unique characteristics of plasmonic metallic nanostructures suggest that this new family of photocatalysts could prove useful for many heterogeneous catalytic processes that cannot be activated using conventional thermal processes on metals or photocatalytic processes on semiconductors.

  2. Unique kinase catalytic mechanism of AceK with a single magnesium ion.

    Directory of Open Access Journals (Sweden)

    Quanjie Li

    Full Text Available Isocitrate dehydrogenase kinase/phosphatase (AceK is the founding member of the protein phosphorylation system in prokaryotes. Based on the novel and unique structural characteristics of AceK recently uncovered, we sought to understand its kinase reaction mechanism, along with other features involved in the phosphotransfer process. Herein we report density functional theory QM calculations of the mechanism of the phosphotransfer reaction catalysed by AceK. The transition states located by the QM calculations indicate that the phosphorylation reaction, catalysed by AceK, follows a dissociative mechanism with Asp457 serving as the catalytic base to accept the proton delivered by the substrate. Our results also revealed that AceK prefers a single Mg(2+-containing active site in the phosphotransfer reaction. The catalytic roles of conserved residues in the active site are discussed.

  3. Crossing the Vascular Wall: Common and Unique Mechanisms Exploited by Different Leukocyte Subsets during Extravasation

    Directory of Open Access Journals (Sweden)

    Michael Schnoor

    2015-01-01

    Full Text Available Leukocyte extravasation is one of the essential and first steps during the initiation of inflammation. Therefore, a better understanding of the key molecules that regulate this process may help to develop novel therapeutics for treatment of inflammation-based diseases such as atherosclerosis or rheumatoid arthritis. The endothelial adhesion molecules ICAM-1 and VCAM-1 are known as the central mediators of leukocyte adhesion to and transmigration across the endothelium. Engagement of these molecules by their leukocyte integrin receptors initiates the activation of several signaling pathways within both leukocytes and endothelium. Several of such events have been described to occur during transendothelial migration of all leukocyte subsets, whereas other mechanisms are known only for a single leukocyte subset. Here, we summarize current knowledge on regulatory mechanisms of leukocyte extravasation from a leukocyte and endothelial point of view, respectively. Specifically, we will focus on highlighting common and unique mechanisms that specific leukocyte subsets exploit to succeed in crossing endothelial monolayers.

  4. Investigation of the Mechanical Performance of Compliant Thermal Barriers

    Science.gov (United States)

    DeMange, Jeffrey J.; Bott, Robert J.; Dunlap, Patrick H.

    2011-01-01

    Compliant thermal barriers play a pivotal role in the thermal protection systems of advanced aerospace vehicles. Both the thermal properties and mechanical performance of these barriers are critical in determining their successful implementation. Due to the custom nature of many thermal barriers, designers of advanced spacecraft have little guidance as to the design, selection, and implementation of these elements. As part of an effort to develop a more fundamental understanding of the interrelationship between thermal barrier design and performance, mechanical testing of thermal barriers was conducted. Two different types of thermal barriers with several core insulation density levels ranging from 62 to 141 kg/cu m were investigated. Room-temperature compression tests were conducted on samples to determine load performance and assess thermal barrier resiliency. Results showed that the loading behavior of these thermal barriers was similar to other porous, low-density, compliant materials, such as elastomeric foams. Additionally, the insulation density level had a significant non-linear impact on the stiffness and peak loads of the thermal barriers. In contrast, neither the thermal barrier type nor the level of insulation density significantly influenced the room-temperature resiliency of the samples.

  5. Mechanism of the Thermal Decomposition of Furan

    Science.gov (United States)

    Vasiliou, Angayle; Ellison, G. Barney; Nimlos, Mark R.; Daily, John W.

    2009-06-01

    Both furan (C_4H_4O) and furfural (C_4H_3O-CHO) areimportant products in biomass pyrolysis. We have used a resistively-heated SiC tubular reactor with a 30 microseconds residence time to study the thermal cracking of furan. The decomposition products are identified by two independent techniques: 118.2 nm VUV photoionization mass spectroscopy and infrared spectroscopy. We observe three different thermal dissociation channels leading to: a) CH_3CCH + CO b) HCCH + CH_2CO c) HCCCH_2.

  6. A unique bivalent binding and inhibition mechanism by the yatapoxvirus interleukin 18 binding protein.

    Directory of Open Access Journals (Sweden)

    Brian Krumm

    Full Text Available Interleukin 18 (IL18 is a cytokine that plays an important role in inflammation as well as host defense against microbes. Mammals encode a soluble inhibitor of IL18 termed IL18 binding protein (IL18BP that modulates IL18 activity through a negative feedback mechanism. Many poxviruses encode homologous IL18BPs, which contribute to virulence. Previous structural and functional studies on IL18 and IL18BPs revealed an essential binding hot spot involving a lysine on IL18 and two aromatic residues on IL18BPs. The aromatic residues are conserved among the very diverse mammalian and poxviruses IL18BPs with the notable exception of yatapoxvirus IL18BPs, which lack a critical phenylalanine residue. To understand the mechanism by which yatapoxvirus IL18BPs neutralize IL18, we solved the crystal structure of the Yaba-Like Disease Virus (YLDV IL18BP and IL18 complex at 1.75 Å resolution. YLDV-IL18BP forms a disulfide bonded homo-dimer engaging IL18 in a 2∶2 stoichiometry, in contrast to the 1∶1 complex of ectromelia virus (ECTV IL18BP and IL18. Disruption of the dimer interface resulted in a functional monomer, however with a 3-fold decrease in binding affinity. The overall architecture of the YLDV-IL18BP:IL18 complex is similar to that observed in the ECTV-IL18BP:IL18 complex, despite lacking the critical lysine-phenylalanine interaction. Through structural and mutagenesis studies, contact residues that are unique to the YLDV-IL18BP:IL18 binding interface were identified, including Q67, P116 of YLDV-IL18BP and Y1, S105 and D110 of IL18. Overall, our studies show that YLDV-IL18BP is unique among the diverse family of mammalian and poxvirus IL-18BPs in that it uses a bivalent binding mode and a unique set of interacting residues for binding IL18. However, despite this extensive divergence, YLDV-IL18BP binds to the same surface of IL18 used by other IL18BPs, suggesting that all IL18BPs use a conserved inhibitory mechanism by blocking a putative receptor

  7. Existence and uniqueness of solutions to the Boussinesq system with nonlinear thermal diffusion

    NARCIS (Netherlands)

    Díaz, J.I.; Galiano, G.

    1997-01-01

    The Boussinesq system arises in Fluid Mechanics when motion is governed by density gradients caused by temperature or concentration differences. In the former case, and when thermodynamical coefficients are regarded as temperature dependent, the system consists of the Navier-Stokes equations and the

  8. Thermal contacts through mechanical moving parts in low thermal budget optical cryogenic assemblies

    Science.gov (United States)

    Testard, O. A.

    Ball bearings or mechanical reductors constitute thermal impedances that can reach the known poor level of thermal radiative exchange at low temperatures, 6 × 10 4 Km -2 W -1. This can induce unacceptable hoop stresses when cooling down high heat capacity components or create thermal heterogeneities on scientific experiments and superconducting devices which are supposed to be cold and isothermic. Soft metallic contacts afford good thermal contacts but cause higher mechanical torque and then increase the heat flux through the contact line. The developments described here were made on one of the four Infrared Space Observatory experiments.

  9. Conserved and plant-unique mechanisms regulating plant post-Golgi traffic

    Directory of Open Access Journals (Sweden)

    Masaru eFujimoto

    2012-08-01

    Full Text Available Membrane traffic plays crucial roles in diverse aspects of cellular and organelle functions in eukaryotic cells. Molecular machineries regulating each step of membrane traffic including the formation, tethering, and fusion of membrane carriers are largely conserved among various organisms, which suggests that the framework of membrane traffic is commonly shared among eukaryotic lineages. However, in addition to the common components, each organism has also acquired lineage-specific regulatory molecules that may be associated with the lineage-specific diversification of membrane trafficking events. In plants, comparative genomic analyses also indicate that some key machineries of membrane traffic are significantly and specifically diversified. In this review, we summarize recent progress regarding plant-unique regulatory mechanisms for membrane traffic, with a special focus on vesicle formation and fusion components in the post-Golgi trafficking pathway.

  10. Structural insights into the unique inhibitory mechanism of the silkworm protease inhibitor serpin18

    Science.gov (United States)

    Guo, Peng-Chao; Dong, Zhaoming; Zhao, Ping; Zhang, Yan; He, Huawei; Tan, Xiang; Zhang, Weiwei; Xia, Qingyou

    2015-01-01

    Serpins generally serve as inhibitors that utilize a mobile reactive center loop (RCL) as bait to trap protease targets. Here, we present the crystal structure of serpin18 from Bombyx mori at 1.65 Å resolution, which has a very short and stable RCL. Activity analysis showed that the inhibitory target of serpin18 is a cysteine protease rather than a serine protease. Notably, this inhibitiory reaction results from the formation of an intermediate complex, which then follows for the digestion of protease and inhibitor into small fragments. This activity differs from previously reported modes of inhibition for serpins. Our findings have thus provided novel structural insights into the unique inhibitory mechanism of serpin18. Furthermore, one physiological target of serpin18, fibroinase, was identified, which enables us to better define the potential role for serpin18 in regulating fibroinase activity during B. mori development. PMID:26148664

  11. Unice cogito, ergo quantum sum (I think uniquely, therefore I am quantum mechanical)

    CERN Document Server

    Svozil, Karl

    2011-01-01

    If the unitary quantum mechanical state evolution is universally valid, quantized systems evolve uniformly, deterministically, and reversible; that is, one-to-one. Hence, what is considered an irreversible measurement might be a purely subjective, conventional, and convenient abstraction of the situation that, although in principal totally reversible, for all practical purposes (fapp), measurements cannot be undone. If this is granted, then Schroedinger's "quantum jellification" arises because of the inevitability of the physical co-existence of classically mutually exclusive states through quantum coherence. It is suggested to take the rather unique human cognitive and perceptive experience as evidence that, at least at the level of apperception, quantum jellification does not exist at all. Otherwise the problems of how to characterize the ambivalence of perception and cognition induced by quantum coherence on a fundamental level of cognition, and why this ambivalence appears to be rather weak and can be ign...

  12. Densely crosslinked polycarbosiloxanes .2. Thermal and mechanical properties

    NARCIS (Netherlands)

    Flipsen, T.A C; Derks, R.; van der Vegt, H.A.; Stenekes, R.; Pennings, A.J; Hadziioannou, G

    1997-01-01

    The thermal and mechanical properties of two densely crosslinked polycarbosiloxane systems were investigated in relation to the molecular structure. The networks were prepared from functional branched prepolymers and crosslinked via a hydrosilylation curing reaction. The prepolymers having only viny

  13. Mechanical properties and thermal behaviour of LLDPE/MWNTs nanocomposites

    Directory of Open Access Journals (Sweden)

    Tai Jin-hua

    2012-12-01

    Full Text Available Multi-walled carbon nanotubes (MWNTs were incorporated into a linear low-density polyethylene (LLDPE matrix through using screw extrusion and injection technique. The effect of different weight percent loadings of MWNTs on the morphology, mechanical, and thermal of LLDPE/MWNTs nanocomposite had been investigated. It was found that, at low concentration of MWNTs, it could uniformly disperse into a linear low-density polyethylene matrix and provide LLDPE/MWNTs nanocomposites much improved mechanical properties. Thermal analysis showed that a clear improvement of thermal stability for LLDPE/MWNTs nanocomposites increased with increasing MWNTs content.

  14. Identifying thermal cycling mechanisms in PWR branch line piping

    Energy Technology Data Exchange (ETDEWEB)

    Rosinski, S.T. [EPRI, Charlotte, NC (United States); Keller, J.D.; Bilanin, A.J. [Continuum Dynamics, Inc., Ewing, NJ (United States)

    2002-07-01

    Predicting the onset and the characteristics of thermal cycling in pressurized water reactor (PWR) branch line piping systems is critical to formulation of thermal fatigue screening tools. The complex nature of the underlying thermal-hydraulic phenomena, however, significantly complicates prediction using analytical models or direct numerical simulations. Instead, it is necessary to perform scaled experiments to identify the physical mechanisms and to gather data for formulation of semi-empirical models for the thermal cycling phenomena. Through the EPRI Materials Reliability Program a test program is underway to identify and develop semi-empirical correlations for the physical thermalhydraulic mechanisms that cause thermal cycling in dead-ended PWR branch line piping systems. Three series of tests are being performed in this test program: configuration tests on a representative up-horizontal (UH) branch line piping geometry, configuration tests on a representative down-horizontal (DH) branch line piping geometry, and high Reynolds number tests to assess penetration of secondary flow structures into a dead-ended branch line. Results from UH and DH configuration tests indicate that random turbulence penetration is not sufficient for thermal cycling to occur. Rather a swirling flow structure, representative of a large, 'corkscrew' vortical structure, is required for thermal cycling. Scale tests on the UH configuration have simulated cycling phenomena observed in full-scale plant data and have been used to determine parametric sensitivities in formulating a predictive model for the thermal cycling. Data indicate that the mechanism for thermal cycling in UH configurations is stochastic but scales with the leak rate from the valve. The critical dependent variables are reduced to several non-dimensional scaling curves, resulting in a semiempirical predictive model. This paper discusses the test program and the results obtained to date. Application of these

  15. Selected studies on the thermal and mechanical responses of amorphous glassy polymers at different length scales

    Science.gov (United States)

    Crawford, Emmett Dudley

    This thesis describes investigations into the mechanical and thermal characteristics of amorphous polymeric materials by structural changes on the molecular and the microscopic scale. On the molecular scale, the structure of a cross-linked polymeric material is controlled by changes in the molecular weight between cross-links, cross-link functionality, and chain stiffness. With control of the network structure, an expansive range of mechanical and thermal characteristics is possible. These properties range from intrinsic properties, such as the glass transition temperature, to performance properties, such as impact behavior. Relationships between the network structure and measured properties are established by the use of a variety of theories from rubber elasticity to free volume. Relationships are also established between the various measured properties through solid and fracture mechanics. The introduction of soft rubbery particles on the microscopic scale into a glassy polymeric matrix is commonly employed to create a tougher material. Despite the prevalent use, the mechanisms and sequence of mechanisms of toughening are poorly understood. The mechanisms and sequence of mechanisms are elucidated in this investigation through the use of unique mechanical tests and materials with favorable properties. The unique mechanical tests in this investigation include tensile dilatometry and a multi-axial stress state test. The multi-axial stress state test, which allows independent control of the dilational and deviatoric stresses of a material between uniaxial compression and equal biaxial tension, consists of a uniaxially loaded and pressurized thin walled hollow cylinder. The materials include liquid rubber modified epoxies, voided epoxies, and core-shell rubber modified polyvinylchloride. The voided epoxy material separates the matrix contributions from those of the rubbery phase, while the core-shell rubber modified polyvinylchloride provides optical verification of

  16. Modeling thermal/chemical/mechanical response of energetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Baer, M.R.; Hobbs, M.L.; Gross, R.J. [and others

    1995-07-01

    An overview of modeling at Sandia National Laboratories is presented which describes coupled thermal, chemical and mechanical response of energetic materials. This modeling addresses cookoff scenarios for safety assessment studies in systems containing energetic materials. Foundation work is discussed which establishes a method for incorporating chemistry and mechanics into multidimensional analysis. Finite element analysis offers the capabilities to simultaneously resolve reactive heat transfer and structural mechanics in complex geometries. Nonlinear conduction heat transfer, with multiple step finite-rate chemistry, is resolved using a thermal finite element code. Rate equations are solved element-by-element using a modified matrix-free stiff solver This finite element software was developed for the simulation of systems requiring large numbers of finite elements. An iterative implicit scheme, based on the conjugate gradient method, is used and a hemi-cube algorithm is employed for the determination of view factors in surface-to-surface radiation transfer The critical link between the reactive heat transfer and mechanics is the introduction of an appropriate constitutive material model providing a stress-strain relationship for quasi-static mechanics analysis. This model is formally derived from bubble nucleation theory, and parameter variations of critical model parameters indicate that a small degree of decomposition leads to significant mechanical response. Coupled thermal/chemical/mechanical analysis is presented which simulates experiments designed to probe cookoff thermal-mechanical response of energetic materials.

  17. Thermalization and its mechanism for generic isolated quantum systems.

    Science.gov (United States)

    Rigol, Marcos; Dunjko, Vanja; Olshanii, Maxim

    2008-04-17

    An understanding of the temporal evolution of isolated many-body quantum systems has long been elusive. Recently, meaningful experimental studies of the problem have become possible, stimulating theoretical interest. In generic isolated systems, non-equilibrium dynamics is expected to result in thermalization: a relaxation to states in which the values of macroscopic quantities are stationary, universal with respect to widely differing initial conditions, and predictable using statistical mechanics. However, it is not obvious what feature of many-body quantum mechanics makes quantum thermalization possible in a sense analogous to that in which dynamical chaos makes classical thermalization possible. For example, dynamical chaos itself cannot occur in an isolated quantum system, in which the time evolution is linear and the spectrum is discrete. Some recent studies even suggest that statistical mechanics may give incorrect predictions for the outcomes of relaxation in such systems. Here we demonstrate that a generic isolated quantum many-body system does relax to a state well described by the standard statistical-mechanical prescription. Moreover, we show that time evolution itself plays a merely auxiliary role in relaxation, and that thermalization instead happens at the level of individual eigenstates, as first proposed by Deutsch and Srednicki. A striking consequence of this eigenstate-thermalization scenario, confirmed for our system, is that knowledge of a single many-body eigenstate is sufficient to compute thermal averages-any eigenstate in the microcanonical energy window will do, because they all give the same result.

  18. DIM (3,3′-diindolylmethane) confers protection against ionizing radiation by a unique mechanism

    Science.gov (United States)

    Fan, Saijun; Meng, Qinghui; Xu, Jiaying; Jiao, Yang; Zhao, Lin; Zhang, Xiaodong; Sarkar, Fazlul H.; Brown, Milton L.; Dritschilo, Anatoly; Rosen, Eliot M.

    2013-01-01

    DIM (3,3′-diindolylmethane), a small molecule compound, is a proposed cancer preventive agent that can be safely administered to humans in repeated doses. We report that administration of DIM in a multidose schedule protected rodents against lethal doses of total body irradiation up to 13 Gy, whether DIM dosing was initiated before or up to 24 h after radiation. Physiologic submicromolar concentrations of DIM protected cultured cells against radiation by a unique mechanism: DIM caused rapid activation of ataxia-telangiectasia mutated (ATM), a nuclear kinase that regulates responses to DNA damage (DDR) and oxidative stress. Subsequently, multiple ATM substrates were phosphorylated, suggesting that DIM induces an ATM-dependent DDR-like response, and DIM enhanced radiation-induced ATM signaling and NF-κB activation. DIM also caused activation of ATM in rodent tissues. Activation of ATM by DIM may be due, in part, to inhibition of protein phosphatase 2A, an upstream regulator of ATM. In contrast, DIM did not protect human breast cancer xenograft tumors against radiation under the conditions tested. In tumors, ATM was constitutively phosphorylated and was not further stimulated by radiation and/or DIM. Our findings suggest that DIM is a potent radioprotector and mitigator that functions by stimulating an ATM-driven DDR-like response and NF-κB survival signaling. PMID:24127581

  19. DIM (3,3'-diindolylmethane) confers protection against ionizing radiation by a unique mechanism.

    Science.gov (United States)

    Fan, Saijun; Meng, Qinghui; Xu, Jiaying; Jiao, Yang; Zhao, Lin; Zhang, Xiaodong; Sarkar, Fazlul H; Brown, Milton L; Dritschilo, Anatoly; Rosen, Eliot M

    2013-11-12

    DIM (3,3'-diindolylmethane), a small molecule compound, is a proposed cancer preventive agent that can be safely administered to humans in repeated doses. We report that administration of DIM in a multidose schedule protected rodents against lethal doses of total body irradiation up to 13 Gy, whether DIM dosing was initiated before or up to 24 h after radiation. Physiologic submicromolar concentrations of DIM protected cultured cells against radiation by a unique mechanism: DIM caused rapid activation of ataxia-telangiectasia mutated (ATM), a nuclear kinase that regulates responses to DNA damage (DDR) and oxidative stress. Subsequently, multiple ATM substrates were phosphorylated, suggesting that DIM induces an ATM-dependent DDR-like response, and DIM enhanced radiation-induced ATM signaling and NF-κB activation. DIM also caused activation of ATM in rodent tissues. Activation of ATM by DIM may be due, in part, to inhibition of protein phosphatase 2A, an upstream regulator of ATM. In contrast, DIM did not protect human breast cancer xenograft tumors against radiation under the conditions tested. In tumors, ATM was constitutively phosphorylated and was not further stimulated by radiation and/or DIM. Our findings suggest that DIM is a potent radioprotector and mitigator that functions by stimulating an ATM-driven DDR-like response and NF-κB survival signaling.

  20. Thermal, chemical, and mechanical response of rigid polyurethane foam

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, M.L.

    1997-12-01

    Rigid polyurethane foams are frequently used as encapsulants to isolate and support thermally sensitive components within weapon systems. When exposed to abnormal thermal environments, such as fire, the polyurethane foam decomposes to form products having a wide distribution of molecular weights and can dominate the overall thermal response of the system. Mechanical response of the decomposing foam, such as thermal expansion under various loading conditions created by gas generation, remains a major unsolved problem. A constitutive model of the reactive foam is needed to describe the coupling between mechanical response and chemical decomposition of foam exposed to environments such as fire. Towards this end, a reactive elastic-plastic constitutive model based on bubble mechanics describing nucleation, decomposition chemistry, and elastic/plastic mechanical behavior of rigid polyurethane foam has been developed. A local force balance, with mass continuity constraints, forms the basis of the constitutive model requiring input of temperature and the fraction of the material converted to gas. This constitutive model provides a stress-strain relationship which is applicable for a broad class of reacting materials such as explosives, propellants, pyrotechnics, and decomposing foams. The model is applied to a block of foam exposed to various thermal fluxes. The model is also applied to a sphere of foam confined in brass. The predicted mechanical deformation of the foam block and sphere are shown to qualitatively agree with experimental observations.

  1. HEAVY AND THERMAL OIL RECOVERY PRODUCTION MECHANISMS

    Energy Technology Data Exchange (ETDEWEB)

    Anthony R. Kovscek; Louis M. Castanier

    2002-09-30

    The Stanford University Petroleum Research Institute (SUPRI-A) conducts a broad spectrum of research intended to help improve the recovery efficiency from difficult to produce reservoirs including heavy oil and fractured low permeability systems. Our scope of work is relevant across near-, mid-, and long-term time frames. The primary functions of the group are to conduct direction-setting research, transfer research results to industry, and educate and train students for careers in industry. Presently, research in SUPRI-A is divided into 5 main project areas. These projects and their goals include: (1) Multiphase flow and rock properties--to develop better understanding of the physics of displacement in porous media through experiment and theory. This category includes work on imbibition, flow in fractured media, and the effect of temperature on relative permeability and capillary pressure. (2) Hot fluid injection--to improve the application of nonconventional wells for enhanced oil recovery and elucidate the mechanisms of steamdrive in low permeability, fractured porous media. (3) Mechanisms of primary heavy oil recovery--to develop a mechanistic understanding of so-called ''foamy oil'' and its associated physical chemistry. (4) In-situ combustion--to evaluate the effect of different reservoir parameters on the insitu combustion process. (5) Reservoir definition--to develop and improve techniques for evaluating formation properties from production information. What follows is a report on activities for the past year. Significant progress was made in all areas.

  2. Molecular mechanisms of unusual thermal resistance of thermophiles; Konetsusei saikin no tainetsu kiko

    Energy Technology Data Exchange (ETDEWEB)

    Oshima, T. [Tokyo Univ. of Pharmacy and Life Science, Tokyo (Japan)

    1997-05-20

    Molecular mechanism of unusual thermal resistance of thermophilic bacteria is reviewed and particularly, studies of heat stability of proteins, enzymes and biomembranes which are important cell constituents are introduced. Thermophiles are found in both eubacteria and archaebacteria and there is no difference of the thermophilic mechanism between them. The concepts of thermal stability and thermophilicity are discussed. From the standpoint of chemical structure, the stability of steric structure of proteins are considered to increase with increase or strengthening of the intermolecular interactions. The thermal stability of DNA is not correlated with the GC content. cDNA is stable thermally and tRNA is stabilized by modification of the structures. Membranes of thermophilic bacteria are thermally stable and membrane lipids of hyperthermophilic bacteria thermous spp. consist of glycolipids with sugar moieties linked to long fatty acids. Membrane lipids of hyperthermophilic acidophilic bacteria of bacillus sp. consist of lipids of a unique structure with a cyclohexane ring, but the relation with the thermal resistance seems to be negative. 6 refs., 5 figs.

  3. Dependence of Glass Mechanical Properties on Thermal and Pressure History

    DEFF Research Database (Denmark)

    Smedskjær, Morten Mattrup; Bauchy, Mathieu

    -equilibrium material, the structure and properties of glass depend not only on its composition, but also on its thermal and pressure histories. Here we review our recent findings regarding the thermal and pressure history dependence of indentation-derived mechanical properties of oxide glasses.......Predicting the properties of new glasses prior to manufacturing is a topic attracting great industrial and scientific interest. Mechanical properties are currently of particular interest given the increasing demand for stronger, thinner, and more flexible glasses in recent years. However, as a non...

  4. In situ thermally reduced graphene oxide/epoxy composites: thermal and mechanical properties

    Science.gov (United States)

    Olowojoba, Ganiu B.; Eslava, Salvador; Gutierrez, Eduardo S.; Kinloch, Anthony J.; Mattevi, Cecilia; Rocha, Victoria G.; Taylor, Ambrose C.

    2016-10-01

    Graphene has excellent mechanical, thermal, optical and electrical properties and this has made it a prime target for use as a filler material in the development of multifunctional polymeric composites. However, several challenges need to be overcome to take full advantage of the aforementioned properties of graphene. These include achieving good dispersion and interfacial properties between the graphene filler and the polymeric matrix. In the present work, we report the thermal and mechanical properties of reduced graphene oxide/epoxy composites prepared via a facile, scalable and commercially viable method. Electron micrographs of the composites demonstrate that the reduced graphene oxide (rGO) is well dispersed throughout the composite. Although no improvements in glass transition temperature, tensile strength and thermal stability in air of the composites were observed, good improvements in thermal conductivity (about 36 %), tensile and storage moduli (more than 13 %) were recorded with the addition of 2 wt% of rGO.

  5. Thermal and mechanical behavior of rubber systems

    Science.gov (United States)

    Macon, David James

    The study of the physical behavior of rubbery materials is motivated by the desire to use these materials in a variety of environments, different mechanical conditions, and at different temperatures. For this to be possible, accurate testing conditions and modeling schemes need to be devised. These tests can be difficult to perform and existing mathematical models often neglect several basic physical requirements. One model is the statistical thermodynamic approach for calculating the thermoelastic behavior of an ideal rubber network, which assumes affine deformation of crosslinked junctions and no internal energy change with isothermal deformation. Yet, when the same relations have been manipulated according to the laws of thermodynamics, an internal energy contribution is revealed. This result is an artifact of improperly referencing strain measures and elasticity coefficients with regard to temperature. When a proper strain reference state is selected, thermoelastic stress-strain-temperature relations result that are totally entropic yet reduce to the usual isothermal conditions. This work proposes a phenomenological model that accurately models existing thermoelastic data. Experimental methods to determine the entropic and energetic contributions to rubber elasticity usually focus on the force-temperature behavior of a uniaxial sample held at constant length. Ideally, these thermoelastic measurements would be made at constant volume. Measurements are made at constant pressure and require complex corrections. It is demonstrated that two dimensionally constrained membrane samples can overcome these difficulties. By using time-average vibrational holographic interferometry, the two principal stresses of a membrane in anisotropic biaxial extension can be directly determined as a function of temperature. This two dimensionally constrained stress-temperature response greatly simplifies the resulting mathematical relations and yields no difference between constant

  6. Gallium a unique anti-resorptive agent in bone: Preclinical studies on its mechanisms of action

    Energy Technology Data Exchange (ETDEWEB)

    Bockman, R.; Adelman, R.; Donnelly, R.; Brody, L.; Warrell, R. (Hospital for Special Surgery, New York, NY (USA)); Jones, K.W. (Brookhaven National Lab., Upton, NY (USA))

    1990-01-01

    The discovery of gallium as a new and unique agent for the treatment of metabolic bone disorders was in part fortuitous. Gallium is an exciting new therapeutic agent for the treatment of pathologic states characterized by accelerated bone resorption. Compared to other therapeutic metal compounds containing platinum or germanium, gallium affects its antiresorptive action without any evidence of a cytotoxic effect on bone cells. Gallium is unique amongst all therapeutically available antiresorptive agents in that it favors bone formation. 18 refs., 1 fig.

  7. Thermal ageing mechanisms of VVER-1000 reactor pressure vessel steels

    Science.gov (United States)

    Shtrombakh, Yaroslav I.; Gurovich, Boris A.; Kuleshova, Evgenia A.; Maltsev, Dmitry A.; Fedotova, Svetlana V.; Chernobaeva, Anna A.

    2014-09-01

    In this paper a complex of microstructural studies (TEM and SEM) and a comparative analysis of the results of these studies with the data of mechanical tests of temperature sets of VVER-1000 RPV surveillance specimens with exposure times up to ∼200,000 h were conducted. Special annealing of control and temperature sets of SS which provides the dissolution of grain boundary segregation was performed to clarify the mechanisms of thermal ageing. It was demonstrated that during long-term exposures up to 200,000 h at the operating temperature of about 310-320 °C thermal ageing effects reveal themselves only for the weld metal (Ni content ⩾ 1.35%) and are the result of grain boundary segregation accumulation (development of reversible temper brittleness). The obtained results improve the accuracy of prediction of the thermal ageing rate of VVER-1000 materials in case of RPV service life extension up to 60 years.

  8. Chemical, thermal and mechanical stabilities of metal-organic frameworks

    Science.gov (United States)

    Howarth, Ashlee J.; Liu, Yangyang; Li, Peng; Li, Zhanyong; Wang, Timothy C.; Hupp, Joseph T.; Farha, Omar K.

    2016-03-01

    The construction of thousands of well-defined, porous, metal-organic framework (MOF) structures, spanning a broad range of topologies and an even broader range of pore sizes and chemical functionalities, has fuelled the exploration of many applications. Accompanying this applied focus has been a recognition of the need to engender MOFs with mechanical, thermal and/or chemical stability. Chemical stability in acidic, basic and neutral aqueous solutions is important. Advances over recent years have made it possible to design MOFs that possess different combinations of mechanical, thermal and chemical stability. Here, we review these advances and the associated design principles and synthesis strategies. We focus on how these advances may render MOFs effective as heterogeneous catalysts, both in chemically harsh condensed phases and in thermally challenging conditions relevant to gas-phase reactions. Finally, we briefly discuss future directions of study for the production of highly stable MOFs.

  9. NONDESTRUCTIVE INVESTIGATION METHODS FOR MECHANICAL EQUIPMENT: THERMAL & ULTRASOUND

    Directory of Open Access Journals (Sweden)

    Marius POPOVICI

    2013-05-01

    Full Text Available Maintenance of mechanical equipment based on NDT methods has seen unprecedented development inrecent years due to the many advantages these methods: investigations are done remotely, without putting theoperator at risk and monitoring mechanical equipment can highlight potential problems that can be detectedlong before they escalate into serious fault. Well-regarded inspection tools include thermal inspections,vibration analysis, oil and ultrasound analysis

  10. Thermal and mechanical modelling of convergent plate margins

    NARCIS (Netherlands)

    van den Beukel, P.J.

    1990-01-01

    In this thesis, the thermal and mechanical structure of convergent plate margins will be investigated by means of numerical modelling. In addition, we will discuss the implications of modelling results for geological processes such as metamorphism or the break-up of a plate at a convergent plate

  11. Thermal-Mechanical Testing of Hypersonic Vehicle Structures

    Science.gov (United States)

    Hudson, Larry; Stephens, Craig

    2007-01-01

    A viewgraph presentation describing thermal-mechanical tests on the structures of hypersonic vehicles is shown. The topics include: 1) U.S. Laboratories for Hot Structures Testing; 2) NASA Dryden Flight Loads Laboratory; 3) Hot Structures Test Programs; 4) Typical Sequence for Hot Structures Testing; 5) Current Hot Structures Testing; and 6) Concluding Remarks.

  12. Thermal and mechanical modelling of convergent plate margins

    NARCIS (Netherlands)

    van den Beukel, P.J.

    1990-01-01

    In this thesis, the thermal and mechanical structure of convergent plate margins will be investigated by means of numerical modelling. In addition, we will discuss the implications of modelling results for geological processes such as metamorphism or the break-up of a plate at a convergent plate mar

  13. Thermal and mechanical modelling of convergent plate margins

    NARCIS (Netherlands)

    Beukel, P.J. van den

    1990-01-01

    In this thesis, the thermal and mechanical structure of convergent plate margins will be investigated by means of numerical modelling. In addition, we will discuss the implications of modelling results for geological processes such as metamorphism or the break-up of a plate at a convergent plate mar

  14. Thermal hydraulic and mechanical analysis of CH HCSB TBM

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-yu; FENG Kai-ming; ZHANG Guo-shu; YUAN Tao

    2006-01-01

    Based on the structure design and results of neutronics analysis of the CH HCSB TBM (Chinese helium cooled solid breeder test blanket module), thermal hydraulic and mechanical analyses have been carried out. Results show that the design of the CH HCSB TBM is reasonable and acceptable.

  15. Integrating Thermal Tools Into the Mechanical Design Process

    Science.gov (United States)

    Tsuyuki, Glenn T.; Siebes, Georg; Novak, Keith S.; Kinsella, Gary M.

    1999-01-01

    The intent of mechanical design is to deliver a hardware product that meets or exceeds customer expectations, while reducing cycle time and cost. To this end, an integrated mechanical design process enables the idea of parallel development (concurrent engineering). This represents a shift from the traditional mechanical design process. With such a concurrent process, there are significant issues that have to be identified and addressed before re-engineering the mechanical design process to facilitate concurrent engineering. These issues also assist in the integration and re-engineering of the thermal design sub-process since it resides within the entire mechanical design process. With these issues in mind, a thermal design sub-process can be re-defined in a manner that has a higher probability of acceptance, thus enabling an integrated mechanical design process. However, the actual implementation is not always problem-free. Experience in applying the thermal design sub-process to actual situations provides the evidence for improvement, but more importantly, for judging the viability and feasibility of the sub-process.

  16. Response of mechanical properties of glasses to their chemical, thermal and mechanical histories

    DEFF Research Database (Denmark)

    Yue, Yuanzheng

    , surface, thermal history or excess entropy of the final glass state. Here I review recent progresses in understanding of the responses of mechanical properties of oxide glasses to the compositional variation, thermal history and mechanical deformation. The tensile strength, elastic modulus and hardness...... of glass fibers are dependent on the thermal history (measured as fictive temperature), tension, chemical composition and redox state. However, the fictive temperature affects the hardness of bulk glass in a complicated manner, i.e., the effect does not exhibit a clear regularity in the range...... and micro-cracks occurring during indentation of a glass is discussed briefly. Finally I describe the future perspectives and challenges in understanding responses of mechanical properties of oxide glasses to compositional variation, thermal history and mechanical deformation....

  17. Mechanical properties testing and results for thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Cruse, T.A.; Johnsen, B.P.; Nagy, A.

    1995-10-01

    The paper reports on several years of mechanical testing of thermal barrier coatings. The test results were generated to support the development of durability models for the coatings in heat engine applications. The test data that are reviewed include modulus, static strength, and fatigue strength data. The test methods and results are discussed, along with the significant difficulties inherent in mechanical testing of thermal barrier coating materials. The materials include 7 percent wt. and 8 percent wt. yttria, partially stabilized zirconia as well as a cermet material. Both low pressure plasma spray and electron-beam physical vapor deposited coatings were tested. The data indicate the basic trends in the mechanical properties of the coatings over a wide range of isothermal conditions. Some of the trends are correlated with material density.

  18. Mechanical properties testing and results for thermal barrier coatings

    Science.gov (United States)

    Cruse, Thomas A.; Johnsen, B. P.; Nagy, Andrew

    1995-01-01

    The paper reports on several years of mechanical testing of thermal barrier coatings. The test results were generated to support the development of durability models for the coatings in heat engine applications. The test data that are reviewed include modulus, static strength, and fatigue strength data. The test methods and results are discussed, along with the significant difficulties inherent in mechanical testing of thermal barrier coating materials. The materials include 7 percent wt. and 8 percent wt. yttria, partially stabilized zirconia as well as a cermet material. Both low pressure plasma spray and electron-beam physical vapor deposited coatings were tested. The data indicate the basic trends in the mechanical properties of the coatings over a wide range of isothermal conditions. Some of the trends are correlated with material density.

  19. Thermal and mechanical improvement of aluminum open-cells foams through electrodeposition of copper and graphene

    Directory of Open Access Journals (Sweden)

    Simoncini Alessandro

    2016-01-01

    Full Text Available Thanks to its planar structure, graphene is characterized by unique properties, such as excellent chemical inactivity, high electrical and thermal conductivity, high optical transparency, extraordinary flexibility and high mechanical resistance, which make it suitable in a very wide range of applications. This paper details the state of the art in graphene coating applied to aluminum open-cells foams for the improvement of their mechanical and thermal behavior. Metallic foams are highly porous materials with extremely high convective heat transfer coefficients, thanks to their complex structure of three-dimensional open-cells. Graphene nanoplatelets have been used to improve thermal conductivity of aluminum foams, to make them better suitable during heat transfer in transient state. Also, an improvement of mechanical resistance has been observed. Before electrodeposition, all the samples have been subjected to sandblasting process, to eliminate the oxide layer on the surface, enabling a better adhesion of the coating. Different nanoparticles of graphene have been used. The experimental findings revealed a higher thermal conductivity for aluminum open cells foams electroplated with graphene. Considered the relatively low process costs and the improvements obtainable, these materials are very promising in many technological fields. The topics covered include surface modification, electrochemical plating, thermo-graphic analysis.

  20. Thermal decomposition of 2-phenylethanol: A computational study on mechanism

    Science.gov (United States)

    Sakai, Yasuyuki; Ando, Hiromitsu; Oguchi, Tatsuo; Murakami, Yoshinori

    2013-01-01

    Quantum mechanical calculations for the thermal decomposition of 2-phenylethanol have been performed using the CBS-QB3 method. Based on the potential energy surfaces at the CBS-QB3 level of theory, the preferred reaction channel for the thermal decomposition of 2-phenylethanol was the six-membered cyclic rearrangement reaction and the dehydration reaction to form styrene and H2O. Further quantum chemical calculations of the subsequent reactions followed by the six-membered cyclic rearrange reaction of 2-phenylethanol were carried out and it was revealed that the barrier height for the ring opening reaction was the lowest among all of the other subsequent reactions.

  1. Investigation of the mechanical and thermal reliability of quilt packaging

    Science.gov (United States)

    Zheng, Quanling

    An interchip interconnection approach based on a new 2-D system-in-package (SiP) method---Quilt Packaging (QP), invented at the University of Notre Dame, is discussed. The principal idea of QP is to assemble a planar mosaic, or "quilt," of dies interconnected by conductive nodules that protrude from vertical faces of ICs. QP offers reduced delay, ultrawide bandwidth, low electrical noise, decreased system size and weight, and the opportunity for heterogeneous integration. In this dissertation, modifications to previous QP fabrication processes are introduced. A new joining method for QP interconnection is presented, using solder paste applied with the pin transfer method, which greatly improves mechanical and thermal reliability, and manufacturability. Chip-to-chip alignment offsets smaller than 1 mum are demonstrated. Simulations and measurements indicate that the microwave performance of QP interconnects provides ultrawide bandwidth. Moreover, the use of solder paste does not significantly degrade the microwave performance of QP. In particular, the return loss associated with the chip-to-chip QP nodules is better than 12.5 dB, and the insertion loss is better than 0.8 dB, at frequencies up to 110 GHz. Mechanical and thermal reliability testing were performed on QP, including pull and thermal shock tests. A novel mechanical testing system that combines a force gauge and a micropull tester was designed and constructed. Pull tests were used to investigate the mechanical strength of QP, and it is found that individual nodules are about as strong as individual wirebonds, but acting together require several pounds of force to separate the chips. Investigations were conducted to learn the effects of thermal shock on all components of the nodule system, including the inter-nodule solder, the copper nodule itself, and the nodule-to-substrate interface layers. Pull tests were performed after thermal shock testing, and it was found that during the first 200 thermal shock

  2. Life prediction of thermal-mechanical fatigue using strainrange partitioning

    Science.gov (United States)

    Halford, G. R.; Manson, S. S.

    1975-01-01

    This paper describes the applicability of the method of Strainrange Partitioning to the life prediction of thermal-mechanical strain-cycling fatigue. An in-phase test on 316 stainless steel is analyzed as an illustrative example. The observed life is in excellent agreement with the life predicted by the method using the recently proposed Step-Stress Method of experimental partitioning, the Interaction Damage Rule, and the life relationships determined at an isothermal temperature of 705 C. Implications of the present study are discussed relative to the general thermal fatigue problem.

  3. Parametric studies of human thermal mechanisms and measurements.

    Science.gov (United States)

    Thornton, S B; Nair, S S

    2000-04-01

    A systematic methodology is proposed for mathematically quantifying the effects of measurement inaccuracies due to instrument uncertainty in a human calorimetry project. Human thermal mechanisms are poorly understood at the systems level and this study investigates the importance of these mechanisms quantitatively. The proposed methodology uses sensitivity derivatives combined with sensor accuracies to quantify the effect of each heat transfer mechanism contributing to the errors in the system equations. The method is applicable to any differentiable model to be validated by experimentation. To illustrate the methodology, two example cases, a reclining nude resting subject and a reclining clothed working subject, are analyzed. The calculated expected errors clearly suggest specific modifications.

  4. Parametric Studies Of Failure Mechanisms In Thermal Barrier Coatings During Thermal Cycling Using FEM

    Directory of Open Access Journals (Sweden)

    Srivathsa B.

    2015-12-01

    Full Text Available Thermal barrier coatings (TBCs are widely used on different hot components of gas turbine engines such as blades and vanes. Although, several mechanisms for the failure of the TBCs have been suggested, it is largely accepted that the durability of these coatings is primarily determined by the residual stresses that are developed during the thermal cycling. In the present study, the residual stress build-up in an electron beam physical vapour deposition (EB-PVD based TBCs on a coupon during thermal cycling has been studied by varying three parameters such as the cooling rate, TBC thickness and substrate thickness. A two-dimensional thermomechanical generalized plane strain finite element simulations have been performed for thousand cycles. It was observed that these variations change the stress profile significantly and the stress severity factor increases non-linearly. Overall, the predictions of the model agree with reported experimental results and help in predicting the failure mechanisms.

  5. Electro-Thermal-Mechanical Simulation Capability Final Report

    Energy Technology Data Exchange (ETDEWEB)

    White, D

    2008-02-06

    This is the Final Report for LDRD 04-ERD-086, 'Electro-Thermal-Mechanical Simulation Capability'. The accomplishments are well documented in five peer-reviewed publications and six conference presentations and hence will not be detailed here. The purpose of this LDRD was to research and develop numerical algorithms for three-dimensional (3D) Electro-Thermal-Mechanical simulations. LLNL has long been a world leader in the area of computational mechanics, and recently several mechanics codes have become 'multiphysics' codes with the addition of fluid dynamics, heat transfer, and chemistry. However, these multiphysics codes do not incorporate the electromagnetics that is required for a coupled Electro-Thermal-Mechanical (ETM) simulation. There are numerous applications for an ETM simulation capability, such as explosively-driven magnetic flux compressors, electromagnetic launchers, inductive heating and mixing of metals, and MEMS. A robust ETM simulation capability will enable LLNL physicists and engineers to better support current DOE programs, and will prepare LLNL for some very exciting long-term DoD opportunities. We define a coupled Electro-Thermal-Mechanical (ETM) simulation as a simulation that solves, in a self-consistent manner, the equations of electromagnetics (primarily statics and diffusion), heat transfer (primarily conduction), and non-linear mechanics (elastic-plastic deformation, and contact with friction). There is no existing parallel 3D code for simulating ETM systems at LLNL or elsewhere. While there are numerous magnetohydrodynamic codes, these codes are designed for astrophysics, magnetic fusion energy, laser-plasma interaction, etc. and do not attempt to accurately model electromagnetically driven solid mechanics. This project responds to the Engineering R&D Focus Areas of Simulation and Energy Manipulation, and addresses the specific problem of Electro-Thermal-Mechanical simulation for design and analysis of energy

  6. Thermal and mechanical stability of zeolitic imidazolate frameworks polymorphs

    Energy Technology Data Exchange (ETDEWEB)

    Bouëssel du Bourg, Lila; Ortiz, Aurélie U.; Coudert, François-Xavier, E-mail: fx.coudert@chimie-paristech.fr [PSL Research University, Chimie ParisTech – CNRS, Institut de Recherche de Chimie Paris, 75005 Paris (France); Boutin, Anne [École Normale Supérieure, PSL Research University, Département de Chimie, Sorbonne Universités – UPMC Univ Paris 06, CNRS UMR 8640 PASTEUR, 24 rue Lhomond, 75005 Paris (France)

    2014-12-01

    Theoretical studies on the experimental feasibility of hypothetical Zeolitic Imidazolate Frameworks (ZIFs) have focused so far on relative energy of various polymorphs by energy minimization at the quantum chemical level. We present here a systematic study of stability of 18 ZIFs as a function of temperature and pressure by molecular dynamics simulations. This approach allows us to better understand the limited stability of some experimental structures upon solvent or guest removal. We also find that many of the hypothetical ZIFs proposed in the literature are not stable at room temperature. Mechanical and thermal stability criteria thus need to be considered for the prediction of new MOF structures. Finally, we predict a variety of thermal expansion behavior for ZIFs as a function of framework topology, with some materials showing large negative volume thermal expansion.

  7. Thermal and mechanical stability of zeolitic imidazolate frameworks polymorphs

    Directory of Open Access Journals (Sweden)

    Lila Bouëssel du Bourg

    2014-12-01

    Full Text Available Theoretical studies on the experimental feasibility of hypothetical Zeolitic Imidazolate Frameworks (ZIFs have focused so far on relative energy of various polymorphs by energy minimization at the quantum chemical level. We present here a systematic study of stability of 18 ZIFs as a function of temperature and pressure by molecular dynamics simulations. This approach allows us to better understand the limited stability of some experimental structures upon solvent or guest removal. We also find that many of the hypothetical ZIFs proposed in the literature are not stable at room temperature. Mechanical and thermal stability criteria thus need to be considered for the prediction of new MOF structures. Finally, we predict a variety of thermal expansion behavior for ZIFs as a function of framework topology, with some materials showing large negative volume thermal expansion.

  8. Enhanced mechanical, thermal, and electric properties of graphene aerogels via supercritical ethanol drying and high-temperature thermal reduction.

    Science.gov (United States)

    Cheng, Yehong; Zhou, Shanbao; Hu, Ping; Zhao, Guangdong; Li, Yongxia; Zhang, Xinghong; Han, Wenbo

    2017-05-03

    Graphene aerogels with high surface areas, ultra-low densities and thermal conductivities have been prepared to exploit their wide applications from pollution adsorption to energy storage, supercapacitor, and thermal insulation. However, the low mechanical properties, poor thermal stability and electric conductivity restrict these aerogels' applications. In this paper, we prepared mechanically strong graphene aerogels with large BET surface areas, low thermal conductivities, high thermal stability and electric conductivities via hydrothermal reduction and supercritical ethanol drying. Annealing at 1500 °C resulted in slightly increased thermal conductivity and further improvement in mechanical properties, oxidation temperature and electric conductivity of the graphene aerogel. The large BET surface areas, together with strong mechanical properties, low thermal conductivities, high thermal stability and electrical conductivities made these graphene aerogels feasible candidates for use in a number of fields covering from batteries to sensors, electrodes, lightweight conductor and insulation materials.

  9. Thermal diffusivity and mechanical properties of polymer matrix composites

    Science.gov (United States)

    Weidenfeller, Bernd; Anhalt, Mathias; Kirchberg, Stefan

    2012-11-01

    Polypropylene-iron-silicon (FeSi) composites with spherical particles and filler content from 0 vol. % to 70 vol. % are prepared by kneading and injection molding. Modulus, crystallinity, and thermal diffusivity of samples are characterized with dynamic mechanical analyzer, differential scanning calorimeter, and laser flash method. Modulus as well as thermal diffusivity of the composites increase with filler fraction while crystallinity is not significantly affected. Measurement values of thermal diffusivity are close to the lower bound of the theoretical Hashin-Shtrikman model. A model interconnectivity shows a poor conductive network of particles. From measurement values of thermal diffusivity, the mean free path length of phonons in the amorphous and crystalline structure of the polymer and in the FeSi particles is estimated to be 0.155 nm, 0.450 nm, and 0.120 nm, respectively. Additionally, the free mean path length of the temperature conduction connected with the electrons in the FeSi particles together with the mean free path in the particle-polymer interface was estimated. The free mean path is approximately 5.5 nm and decreases to 2.5 nm with increasing filler fraction, which is a result of the increasing area of polymer-particle interfaces. A linear dependence of thermal diffusivity with the square root of the modulus independent on the measurement temperature in the range from 300 K to 415 K was found.

  10. Thermal noise free opto-mechanics using strong optical springs

    CERN Document Server

    Page, Michael; Zhao, Chunnong; Blair, David; Ju, Li; Pan, Huang-Wei; Chao, Shiuh; Mitrofanov, Valery; Sadeghian, Hamed

    2016-01-01

    Thermal noise generally greatly exceeds quantum noise in optomechanical devices unless the mechanical frequency is very high or the thermodynamic temperature is very low. This paper addresses the design concept for a novel optomechanical device capable of ultrahigh quality factors with negligible thermal noise. The proposed system consists of a minimally supported millimeter scale pendulum mounted in a Double End-Mirror Sloshing (DEMS) cavity that is topologically equivalent to a Membrane-in-the-Middle (MIM) cavity. The radiation pressure inside the high-finesse cavity allows for high optical stiffness, cancellation of terms which lead to unwanted negative damping and suppression of quantum radiation pressure noise. We solve for the optical spring dynamics of the system using the Hamiltonian, find the noise spectral density and show that stable optical trapping is possible. We also assess various loss mechanisms, one of the most important being the acceleration loss due to the optical spring. We show that pra...

  11. 4D Printing with Mechanically Robust, Thermally Actuating Hydrogels.

    Science.gov (United States)

    Bakarich, Shannon E; Gorkin, Robert; in het Panhuis, Marc; Spinks, Geoffrey M

    2015-06-01

    A smart valve is created by 4D printing of hydrogels that are both mechanically robust and thermally actuating. The printed hydrogels are made up of an interpenetrating network of alginate and poly(N-isopropylacrylamide). 4D structures are created by printing the "dynamic" hydrogel ink alongside other static materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Study on Thermal and Mechanical Properties of EPDM Insulation

    Science.gov (United States)

    Zhang, Zhong-Shui; Xu, Jin-Sheng; Chen, Xiong; Jiang, Jing

    As the most common insulation material of solid rocket motors, thermal and mechanical properties of ethylene propylene diene monomer (EPDM) composite are inspected in the study. Referring to the results of thermogravimetric analysis (TGA), composition and morphology of EPDM composite in different thermal degradation degree are investigated by scanning electron microscope (SEM) to inspect the mechanism of thermal insulation. Mechanical properties of EPDM composite in the state of pyrolysis are investigated by uniaxial tensile tests. At the state of initial pyrolysis, composite belongs to the category of hyperelastic-viscoelastic material. The tendency of tensile strength increased and elongation decreased with increasing of heating temperature. Composite behaves as the linear rule at the state of late pyrolysis, which belongs to the category of bittle. The elasticity modulus of curves are almost the same while the heating temperature ranges from 200°C to 300°C, and then gradually go down. The tensile strength of pyrolytic material reach the highest at the heating temperature of 300°C, and the virgin material has the largest elongation.

  13. On the uniqueness of paths for spin-0 and spin-1 quantum mechanics

    Science.gov (United States)

    Struyve, W.; De Baere, W.; De Neve, J.; De Weirdt, S.

    2004-02-01

    The uniqueness of the Bohmian particle interpretation of the Kemmer equation, which describes massive spin-0 and spin-1 particles, is discussed. Recently the same problem for spin-(1/2) was dealt with by Holland. It appears that the uniqueness of boson paths can be enforced under well determined conditions. This in turn fixes the nonrelativistic particle equations of the nonrelativistic Schrödinger equation, which appear to correspond with the original definitions given by de Broglie and Bohm only in the spin-0 case. Similar to the spin-(1/2) case, there appears an additional spin-dependent term in the guidance equation in the spin-1 case. We also discuss the ambiguity associated with the introduction of an electromagnetic coupling in the Kemmer theory. We argue that when the minimal coupling is correctly introduced, then the current constructed from the energy-momentum tensor is no longer conserved. Hence this current cannot serve as a particle probability four-vector.

  14. Thermal Stresses in a Cylinder Block Casting Due to Coupled Thermal and Mechanical Effects

    Institute of Scientific and Technical Information of China (English)

    XU Yan; KANG Jinwu; HUANG Tianyou; HU Yongyi

    2008-01-01

    Thermal stress in castings results from nonuniform cooling. The thermal stress and the deforma-tion can change the casting and mold contact conditions which then alter the heat transfer between the cast-ing and the mold. The contact element method was used to study the interaction between a sand mold and a casting. The contact status was then fed back to the heat transfer analysis between the sand mold and the casting to re-evaluate the heat transfer coefficient based on the gap size or pressure between surfaces. The thermal and mechanical phenomena are then coupled in two directions. The method was applied to analyze stress in a stress frame specimen casting and a cylinder block. The results are more accurate than without consideration of the contact effects on the heat transfer.

  15. Failure Mechanisms and Life Prediction of Thermal and Environmental Barrier Coatings under Thermal Gradients

    Science.gov (United States)

    Zju, Dongming; Ghosn, Louis J.; Miller, Robert A.

    2008-01-01

    Ceramic thermal and environmental barrier coatings (TEBCs) will play an increasingly important role in gas turbine engines because of their ability to further raise engine temperatures. However, the issue of coating durability is of major concern under high-heat-flux conditions. In particular, the accelerated coating delamination crack growth under the engine high heat-flux conditions is not well understood. In this paper, a laser heat flux technique is used to investigate the coating delamination crack propagation under realistic temperature-stress gradients and thermal cyclic conditions. The coating delamination mechanisms are investigated under various thermal loading conditions, and are correlated with coating dynamic fatigue, sintering and interfacial adhesion test results. A coating life prediction framework may be realized by examining the crack initiation and propagation driving forces for coating failure under high-heat-flux test conditions.

  16. Hemp Thermal Insulation Concrete with Alternative Binders, Analysis of their Thermal and Mechanical Properties

    Science.gov (United States)

    Sinka, M.; Sahmenko, G.; Korjakins, A.; Radina, L.; Bajare, D.

    2015-11-01

    One of the main challenges that construction industry faces today is how to address the demands for more sustainable, environmentally friendly and carbon neutral construction materials and building upkeep processes. One of the answers to these demands is lime-hemp concrete (LHC) building materials - carbon negative materials that have sufficient thermal insulation capabilities to be used as thermal insulation materials for new as well as for existing buildings. But one problem needs to be overcome before these materials can be used on a large scale - current manufacturing technology allows these materials to be used only as self-bearing thermal insulation material with large labour intensity in the manufacturing process. In order to lower the labour intensity and allow the material to be used in wider applications, a LHC block and board production is necessary, which in turn calls for the binders different from the classically used ones, as they show insufficient mechanical strength for this new use. The particular study focuses on alternative binders produced using gypsum-cement compositions ensuring they are usable in outdoor applications together with hemp shives. Physical, mechanical, thermal and water absorption properties of hemp concrete with various binders are addressed in the current study.

  17. Mechanism of the Thermal Decomposition of Ethanethiol and Dimethylsulfide

    Science.gov (United States)

    Melhado, William Francis; Whitman, Jared Connor; Kong, Jessica; Anderson, Daniel Easton; Vasiliou, AnGayle (AJ)

    2016-06-01

    Combustion of organosulfur contaminants in petroleum-based fuels and biofuels produces sulfur oxides (SO_x). These pollutants are highly regulated by the EPA because they have been linked to poor respiratory health and negative environmental impacts. Therefore much effort has been made to remove sulfur compounds in petroleum-based fuels and biofuels. Currently desulfurization methods used in the fuel industry are costly and inefficient. Research of the thermal decomposition mechanisms of organosulfur species can be implemented via engineering simulations to modify existing refining technologies to design more efficient sulfur removal processes. We have used a resistively-heated SiC tubular reactor to study the thermal decomposition of ethanethiol (CH_3CH_2SH) and dimethylsulfide (CH_3SCH_3). The decomposition products are identified by two independent techniques: 118.2 nm VUV photoionization mass spectroscopy and infrared spectroscopy. The thermal cracking products for CH_3CH_2SH are CH_2CH_2, SH, and H_2S and the thermal cracking products from CH_3SCH_3 are CH_3S, CH_2S, and CH_3.

  18. Nanobioceramic Composites: A Study of Mechanical, Morphological, and Thermal Properties

    Directory of Open Access Journals (Sweden)

    Sivabalan Sasthiryar

    2013-12-01

    Full Text Available The aim of this study was to explore the incorporation of biomass carbon nanofillers (CNF into advanced ceramic. Biomass from bamboo, bagasse (remains of sugarcane after pressing, and oil palm ash was used as the predecessor for producing carbon black nanofillers. Furnace pyrolysis was carried out at 1000 °C and was followed by ball-mill processing to obtain carbon nanofillers in the range of 50 nm to 100 nm. CNFs were added to alumina in varying weight fractions and the resulting mixture was subjected to vacuum sintering at 1400 °C to produce nanobioceramic composites. The ceramic composites were characterized for mechanical, thermal, and morphological properties. A high-resolution Charge-coupled device (CCD camera was used to study the fracture impact and the failure mechanism. An increase in the loading percentage of CNFs in the alumna decreased the specific gravity, vickers hardness (HV, and fracture toughness values of the composite materials. Furthermore, the thermal conductivity and the thermal stability of the ceramic composite increased as compared to the pristine alumina.

  19. Downstream evolution of unconfined vortices: mechanical and thermal aspects

    Science.gov (United States)

    Pérez-Saborid, M.; Herrada, M. A.; Gómez-Barea, A.; Barrero, A.

    2002-11-01

    We present a numerical study of the downstream evolution (mechanical and thermal) of vortex-jet cores whose velocity and temperature fields far from the axis match a family of inviscid and non-conducting vortices. The far-velocity field is rotational, except for a particular case which corresponds to the well-known Long's vortex. The evolution of the vortex core depends on both the conditions at a certain upstream station, characterized by the dimensionless value of the velocity at the axis, and a dimensionless swirling parameter L defined as the ratio of the values of the azimuthal and axial velocities outside the vortex core. This numerical study, based on the quasi-cylindrical approximation (QC) of the Navier Stokes equations, determines the conditions under which the vortex evolution proceeds smoothly, eventually reaching an asymptotic self-similar behaviour as described in the literature (Fernández-Feria, Fernández de la Mora & Barrero 1995; Herrada, Pérez-Saborid & Barrero 1999), or breaks in a non-slender solution (vortex breakdown). In particular, the critical value L = Lb(a) beyond which vortex breakdown occurs downstream is a function of a dimensionless parameter a characterizing the axial momentum of the vortex jet at an initial upstream station. It is found numerically that for very large values of a this vortex breakdown criterion tends to an asymptote which is precisely the value L = L* predicted by the self-similar analysis, and beyond which a self-similar structure of the vortex core does not exist. In addition, the computation of the total temperature field provides useful information on the physical mechanisms responsible for the thermal separation phenomenon observed in Ranque Hilsch tubes and other swirling jet devices. In particular, the mechanical work of viscous forces which gives rise to an intense loss of kinetic energy during the initial stages of the evolution has been identified as the physical mechanism responsible for thermal

  20. THE INTRODUCTION OF THE UNIQUE MECHANISM OF SURVEILLANCE AND THE REDUCTION OF NON-PERFORMING LOANS

    Directory of Open Access Journals (Sweden)

    Nicoleta Georgeta PANAIT

    2014-05-01

    Full Text Available The introduction of a harmonized framework for financial supervision allows the minimizing of tax consequences and possible systemic bank failures. Banking union project will have impact on both the micro-prudential supervisory practices and the prudential supervision framework in the euro area and in the state members that will decide to participate in this project. The non-performing loans (NPL trend in the countries of Southeastern Europe further shows that nonperforming loans will increase in some of the states of Eastern Europe affecting credit flows and profits made by the banks. The activities conducted by the banks cannot be estimated, quantified and especially eliminate all risk, lending generates NPL even lending procedures were followed in accordance with the laws and regulations in force. Romania has the highest rate of non-performing loans in the region and the fact is generated because of difficulties in removing non performing loans from banks' balance sheets. In order to increase the volume of loans it is necessary to decrease of nonperforming loans from banks' balance sheets. To identify the optimal strategy for managing non-performing loans is necessary to continually monitor the performance and providing rapid adaptation to the dynamic environmental factors and changes in the characteristics of the loan portfolio. European Central Bank will consistently enforce a set of unique rules apply to the group of euro area credit institutions will directly supervise credit large institutions and will monitor supervisory practices of credit institutions less significant conducted by competent national authorities.

  1. Coupled mechanical and thermal simulation of warm compaction

    Institute of Scientific and Technical Information of China (English)

    LI Yuan-yuan; ZHAO Wei-bin; ZHOU Zhao-yao; CHEN Pu-qing

    2006-01-01

    Warm compaction process of pure iron powder was investigated. Due to the existence of elastic, plastic and thermal strains,a coupled mechanical and thermal model was applied. The elasto-plastic constitutive equations for powder material were developed based on ellipsoidal yield criterion and continuum theory. The constitutive equations were integrated into the constitutive integral arithmetic and solved employing incremental iterative solution strategy. The yield strength of iron powder was obtained according to the tensile experiments. When the compaction temperature was raised to 130 ℃, the yield strength of iron powder metal drops to 85% of room temperature value. Modified coulomb friction law is applied and the simulation results show that friction was an important factor resulting in the inhomogeneous relative density and reverse-density distribution phenomena in the regions near the die wall and the symmetrical axis.

  2. Crystal structure of an invertebrate cytolysin pore reveals unique properties and mechanism of assembly

    Science.gov (United States)

    Podobnik, Marjetka; Savory, Peter; Rojko, Nejc; Kisovec, Matic; Wood, Neil; Hambley, Richard; Pugh, Jonathan; Wallace, E. Jayne; McNeill, Luke; Bruce, Mark; Liko, Idlir; Allison, Timothy M.; Mehmood, Shahid; Yilmaz, Neval; Kobayashi, Toshihide; Gilbert, Robert J. C.; Robinson, Carol V.; Jayasinghe, Lakmal; Anderluh, Gregor

    2016-05-01

    The invertebrate cytolysin lysenin is a member of the aerolysin family of pore-forming toxins that includes many representatives from pathogenic bacteria. Here we report the crystal structure of the lysenin pore and provide insights into its assembly mechanism. The lysenin pore is assembled from nine monomers via dramatic reorganization of almost half of the monomeric subunit structure leading to a β-barrel pore ~10 nm long and 1.6-2.5 nm wide. The lysenin pore is devoid of additional luminal compartments as commonly found in other toxin pores. Mutagenic analysis and atomic force microscopy imaging, together with these structural insights, suggest a mechanism for pore assembly for lysenin. These insights are relevant to the understanding of pore formation by other aerolysin-like pore-forming toxins, which often represent crucial virulence factors in bacteria.

  3. Corynebacterium diphtheriae methionine sulfoxide reductase a exploits a unique mycothiol redox relay mechanism.

    Science.gov (United States)

    Tossounian, Maria-Armineh; Pedre, Brandán; Wahni, Khadija; Erdogan, Huriye; Vertommen, Didier; Van Molle, Inge; Messens, Joris

    2015-05-01

    Methionine sulfoxide reductases are conserved enzymes that reduce oxidized methionines in proteins and play a pivotal role in cellular redox signaling. We have unraveled the redox relay mechanisms of methionine sulfoxide reductase A of the pathogen Corynebacterium diphtheriae (Cd-MsrA) and shown that this enzyme is coupled to two independent redox relay pathways. Steady-state kinetics combined with mass spectrometry of Cd-MsrA mutants give a view of the essential cysteine residues for catalysis. Cd-MsrA combines a nucleophilic cysteine sulfenylation reaction with an intramolecular disulfide bond cascade linked to the thioredoxin pathway. Within this cascade, the oxidative equivalents are transferred to the surface of the protein while releasing the reduced substrate. Alternatively, MsrA catalyzes methionine sulfoxide reduction linked to the mycothiol/mycoredoxin-1 pathway. After the nucleophilic cysteine sulfenylation reaction, MsrA forms a mixed disulfide with mycothiol, which is transferred via a thiol disulfide relay mechanism to a second cysteine for reduction by mycoredoxin-1. With x-ray crystallography, we visualize two essential intermediates of the thioredoxin relay mechanism and a cacodylate molecule mimicking the substrate interactions in the active site. The interplay of both redox pathways in redox signaling regulation forms the basis for further research into the oxidative stress response of this pathogen.

  4. Quantum chemical aided prediction of the thermal decomposition mechanisms and temperatures of ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Kroon, Maaike C. [Physical Chemistry and Molecular Thermodynamics, Department of Chemical Technology, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 136, 2628 BL Delft (Netherlands); Process Equipment, Department of Process and Energy, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 44, 2628 CA Delft (Netherlands)], E-mail: maaike.kroon@gmail.com; Buijs, Wim [Catalysis Engineering, Department of Chemical Technology, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 136, 2628 BL Delft (Netherlands); Peters, Cor J. [Physical Chemistry and Molecular Thermodynamics, Department of Chemical Technology, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 136, 2628 BL Delft (Netherlands); Witkamp, Geert-Jan [Process Equipment, Department of Process and Energy, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 44, 2628 CA Delft (Netherlands)], E-mail: G.J.Witkamp@3me.tudelft.nl

    2007-12-15

    The long-term thermal stability of ionic liquids is of utmost importance for their industrial application. Although the thermal decomposition temperatures of various ionic liquids have been measured previously, experimental data on the thermal decomposition mechanisms and kinetics are scarce. It is desirable to develop quantitative chemical tools that can predict thermal decomposition mechanisms and temperatures (kinetics) of ionic liquids. In this work ab initio quantum chemical calculations (DFT-B3LYP) have been used to predict thermal decomposition mechanisms, temperatures and the activation energies of the thermal breakdown reactions. These quantum chemical calculations proved to be an excellent method to predict the thermal stability of various ionic liquids.

  5. Effect of thermal stresses on the mechanism of tooth pain.

    Science.gov (United States)

    Oskui, Iman Z; Ashtiani, Mohammed N; Hashemi, Ata; Jafarzadeh, Hamid

    2014-11-01

    Daily hot and cold thermal loadings on teeth may result in structural deformation, mechanical stress, and pain signaling. The aim of this study was to compare the adverse effects of hot and cold beverages on an intact tooth and, then, to provide physical evidence to support the hydrodynamic theory of tooth pain sensation mechanism. Three-dimensional finite element analysis was performed on a premolar model subjected to hot and cold thermal loadings. Elapsed times for heat diffusion and stress detection at the pulp-dentin junction were calculated as measures of the pain sensation. Extreme tensile stress within the enamel resulted in damage in cold loadings. Also, extreme values of stress at the pulpal wall occurred 21.6 seconds earlier than extreme temperatures in hot and cold loadings. The intact tooth was remarkably vulnerable to cold loading. Earlier changes in mechanical stress rather than temperature at the pulp-dentin junction indicate that the dental pain caused by hot or cold beverages may be based on the hydrodynamic theory. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  6. The mechanical and thermal setup of the GLORIA spectrometer

    Directory of Open Access Journals (Sweden)

    C. Piesch

    2014-11-01

    Full Text Available The novel airborne Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA measures infrared emission of atmospheric trace constituents. GLORIA comprises a cooled imaging Fourier transform spectrometer which is operated in unpressurized aircraft compartments at ambient temperature. The whole spectrometer is pointed by the gimbal towards the atmospheric target. In order to reach the required sensitivity for atmospheric emission measurements the spectrometer optics needs to operate at a temperature below 220 K. A lightweight and compact design is mandatory due to limited space and high agility requirements. The cooled optical system needs to withstand high pressure and temperature gradients, humidity, and vibrations. A new cooling system based on carbon dioxide and liquid nitrogen combined with high-performance insulation has been developed to meet the mechanical, thermal, and logistical demands. The challenging mechanical and spatial requirements lead to the development of a novel rigid linear slide design in order to achieve the large optical path difference for high spectral resolution. This paper describes the mechanical and thermal setup of GLORIA and presents the performance results on two different research aircrafts.

  7. The mechanical and thermal setup of the GLORIA spectrometer

    Science.gov (United States)

    Piesch, C.; Sartorius, C.; Friedl-Vallon, F.; Gulde, T.; Heger, S.; Kretschmer, E.; Maucher, G.; Nordmeyer, H.; Barthel, J.; Ebersoldt, A.; Graf, F.; Hase, F.; Kleinert, A.; Neubert, T.; Schillings, H. J.

    2015-04-01

    The novel airborne Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) measures infrared emission of atmospheric trace constituents. GLORIA comprises a cooled imaging Fourier transform spectrometer, which is operated in unpressurized aircraft compartments at ambient temperature. The whole spectrometer is pointed by the gimbal towards the atmospheric target. In order to reach the required sensitivity for atmospheric emission measurements, the spectrometer optics needs to operate at a temperature below 220 K. A lightweight and compact design is mandatory due to limited space and high agility requirements. The cooled optical system needs to withstand high pressure and temperature gradients, humidity, and vibrations. A new cooling system based on carbon dioxide and liquid nitrogen combined with high-performance insulation has been developed to meet the mechanical, thermal, and logistical demands. The challenging mechanical and spatial requirements lead to the development of a novel rigid linear slide design in order to achieve the large optical path difference for high spectral resolution. This paper describes the mechanical and thermal setup of GLORIA and presents the performance results on two different research aircrafts.

  8. Mechanical, Thermal and Dynamic Mechanical Properties of PP/GF/xGnP Nanocomposites

    Science.gov (United States)

    Ashenai Ghasemi, F.; Ghorbani, A.; Ghasemi, I.

    2017-03-01

    The mechanical, thermal, and dynamic mechanical properties of ternary nanocomposites based on polypropylene, short glass fibers, and exfoliated graphene nanoplatelets were studied. To investigate the mechanical properties, uniaxial tensile and Charpy impact tests were carried out. To study the crystallinity of the compositions, a DSC test was performed. A dynamic mechanical analysis was used to characterize the storage modulus and loss factor (tan δ). The morphology of the composites was studied by a scanning electron microscope (SEM). The results obtained are presented in tables and graphics.

  9. Swarming populations of Salmonella represent a unique physiological state coupled to multiple mechanisms of antibiotic resistance

    Directory of Open Access Journals (Sweden)

    Kim Wook

    2003-01-01

    Full Text Available Salmonella enterica serovar Typhimurium is capable of swarming over semi-solid surfaces. Although its swarming behavior shares many readily observable similarities with other swarming bacteria, the phenomenon remains somewhat of an enigma in this bacterium since some attributes skew away from the better characterized systems. Swarming is quite distinct from the classic swimming motility, as there is a prerequisite for cells to first undergo a morphological transformation into swarmer cells. In some organisms, swarming is controlled by quorum sensing, and in others, swarming has been shown to be coupled to increased expression of important virulence factors. Swarming in serovar Typhimurium is coupled to elevated resistance to a wide variety of structurally and functionally distinct classes of antimicrobial compounds. As serovar Typhimurium differentiates into swarm cells, the pmrHFIJKLM operon is up-regulated, resulting in a more positively charged LPS core. Furthermore, as swarm cells begin to de-differentiate, the pmr operon expression is down-regulated, rapidly reaching the levels observed in swim cells. This is one potential mechanism which confers swarm cells increased resistance to antibiotics such as the cationic antimicrobial peptides. However, additional mechanisms are likely associated with the cells in the swarm state that confer elevated resistance to such a broad spectrum of antimicrobial agents.

  10. Nociceptive responses to thermal and mechanical stimulations in awake pigs

    DEFF Research Database (Denmark)

    di Giminiani, Pierpaolo; Petersen, Lars Jelstrup; Herskin, Mette S.

    2013-01-01

    animal studies in a large species require further examination. This manuscript describes the initial development of a porcine model of cutaneous nociception and focuses on interactions between the sensory modality, body size and the anatomical location of the stimulation site. METHODS: Pigs of different...... significantly lower pain thresholds (shorter latency to response) than large pigs to thermal and mechanical stimulations. Stimulations at the two anatomical locations elicited very distinct sets of behavioural responses, with different levels of sensitivity between the flank and the hind legs. Furthermore...

  11. A mechanical-thermal noise analysis of a nonlinear microgyroscope

    Science.gov (United States)

    Lajimi, S. A. M.; Heppler, G. R.; Abdel-Rahman, E. M.

    2017-01-01

    The mechanical-thermal noise (MTN) equivalent rotation rate (Ωn) is computed by using the linear approximation of the system response and the nonlinear "slow" system. The slow system, which is obtained using the method of multiple scales, is used to identify the linear single-valued response of the system. The linear estimate of the noise equivalent rate fails as the drive direction stroke increases. It becomes imperative in these conditions to use a more complex nonlinear estimate of the noise equivalent rate developed here for the first time in literature. The proposed design achieves a high performance regarding noise equivalent rotation rate.

  12. Agave nonwovens in polypropylene composites: mechanical and thermal studies

    CSIR Research Space (South Africa)

    John

    2015-03-01

    Full Text Available stream_source_info John_2015.pdf.txt stream_content_type text/plain stream_size 27570 Content-Encoding UTF-8 stream_name John_2015.pdf.txt Content-Type text/plain; charset=UTF-8 1 Agave nonwovens... in polypropylene composites – Mechanical and thermal studies Maya Jacob John1, 2 , Nokuzola Sikampula1 and Lydia Boguslavsky1 1CSIR Materials Science and Manufacturing, Fibres and Textiles Competence Area, P.O. Box 1124, Port Elizabeth 6000, South Africa...

  13. Response of mechanical properties of glasses to their chemical, thermal and mechanical histories

    DEFF Research Database (Denmark)

    Yue, Yuanzheng

    , surface, thermal history or excess entropy of the final glass state. Here I review recent progresses in understanding of the responses of mechanical properties of oxide glasses to the compositional variation, thermal history and mechanical deformation. The tensile strength, elastic modulus and hardness...... and hardness of glass fibers are strongly correlated with the glass composition, fictive temperature, axial tension, and redox state. This correlation is explained by considering both the bulk and the surface glass structure. Furthermore, the compositional dependence of the densification extent, plastic flow...... of glass fibers are dependent on the thermal history (measured as fictive temperature), tension, chemical composition and redox state. However, the fictive temperature affects the hardness of bulk glass in a complicated manner, i.e., the effect does not exhibit a clear regularity in the range...

  14. Monitoring Local Strain in a Thermal Barrier Coating System Under Thermal Mechanical Gas Turbine Operating Conditions

    Science.gov (United States)

    Manero, Albert; Sofronsky, Stephen; Knipe, Kevin; Meid, Carla; Wischek, Janine; Okasinski, John; Almer, Jonathan; Karlsson, Anette M.; Raghavan, Seetha; Bartsch, Marion

    2015-07-01

    Advances in aircraft and land-based turbine engines have been increasing the extreme loading conditions on traditional engine components and have incited the need for improved performance with the use of protective coatings. These protective coatings shield the load-bearing super alloy blades from the high-temperature combustion gases by creating a thermal gradient over their thickness. This addition extends the life and performance of blades. A more complete understanding of the behavior, failure mechanics, and life expectancy for turbine blades and their coatings is needed to enhance and validate simulation models. As new thermal-barrier-coated materials and deposition methods are developed, strides to effectively test, evaluate, and prepare the technology for industry deployment are of paramount interest. Coupling the experience and expertise of researchers at the University of Central Florida, The German Aerospace Center, and Cleveland State University with the world-class synchrotron x-ray beam at the Advanced Photon Source in Argonne National Laboratory, the synergistic collaboration has yielded previously unseen measurements to look inside the coating layer system for in situ strain measurements during representative service loading. These findings quantify the in situ strain response on multilayer thermal barrier coatings and shed light on the elastic and nonelastic properties of the layers and the role of mechanical load and internal cooling variations on the response. The article discusses the experimental configuration and development of equipment to perform in situ strain measurements on multilayer thin coatings and provides an overview of the achievements thus far.

  15. Algebraic roots of Newtonian mechanics: correlated dynamics of particles on a unique worldline

    CERN Document Server

    Kassandrov, Vladimir V

    2012-01-01

    In development of the old ideas of Stueckelberg-Wheeler-Feynman on "one-electron Universe", we study purely algebraic dynamics of (two kinds of) identical pointlike particles. These are represented by (real and complex conjugate) roots of a generic polynomial system of equations that implicitly defines a single "Worldline". The dynamics includes, in particular, events of "merging" of some two particles modelling the processes of annihilation/creation and the "exchange of quantum" as well. Correlations in the location and motion of the particles-roots relate, in particular, to the Vieta's formulas. After special choice of the inertial-like reference frame, the linear Vieta's formula ensures satisfaction of the law of (non-relativistic) momentum conservation and reproduces thus general structure of the Newtonian mechanics. Some considerations on relativization of the scheme are presented.

  16. Mechanical and thermal properties of bulk ZrB2

    Science.gov (United States)

    Nakamori, Fumihiro; Ohishi, Yuji; Muta, Hiroaki; Kurosaki, Ken; Fukumoto, Ken-ichi; Yamanaka, Shinsuke

    2015-12-01

    ZrB2 appears to have formed in the fuel debris at the Fukushima Daiichi nuclear disaster site, through the reaction between Zircaloy cladding materials and the control rod material B4C. Since ZrB2 has a high melting point of 3518 K, the ceramic has been widely studied as a heat-resistant material. Although various studies on the thermochemical and thermophysical properties have been performed for ZrB2, significant differences exist in the data, possibly due to impurities or the porosity within the studied samples. In the present study, we have prepared a ZrB2 bulk sample with 93.1% theoretical density by sintering ZrB2 powder. On this sample, we have comprehensively examined the thermal and mechanical properties of ZrB2 by the measurement of specific heat, ultrasonic sound velocities, thermal diffusivity, and thermal expansion. Vickers hardness and fracture toughness were also measured and found to be 13-23 GPa and 1.8-2.8 MPa m0.5, respectively. The relationships between these properties were carefully examined in the present study.

  17. Synthesis, Characterization and Thermal Decomposition Mechanism of Cetyltrimethyl Ammonium Tetrathiotungstate

    Institute of Scientific and Technical Information of China (English)

    Gaojun An; Yunqi Liu; Yongming Chai; Hongyan Shang; Chenguang Liu

    2006-01-01

    The synthesis, characterization and thermal decomposition mechanism of cetyltrimethyl ammonium tetrathiotungstate (CTriMATT) were studied herein. The as-synthesized CTriMATT was characterized by Elemental analysis, X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Ultraviolet visible (UV-Vis) spectra. The results showed that the as-synthesized CTriMATT had high purity and good crystallinity. The introduction of alkyl groups induced a shift of the stretching vibration band of W-S bond to lower wavenumber, while it had no influence on the position of WS2-4. Thermogravimetric analysis (TG), differential thermal analysis (DTA) and in situ XRD characterizations revealed that CTriMATT began to decompose at 423 K in nitrogen and was converted to WS2 eventually. In addition,the decomposition product of CTriMATT at 673 K in nitrogen was characterized by N2 adsorption (BET)and scanning electron microscopy (SEM). The results demonstrated that WS2 with higher specific surface area, and pore volume could be obtained from the thermal decomposition of CTriMATT in nitrogen.

  18. Sintering Densification Mechanism of Talc on Promoting Thermal Storage Andalusite Ceramics in Solar Thermal Power Generation

    Institute of Scientific and Technical Information of China (English)

    WU Jianfeng; CHENG Hao; XU Xiaohong; LAO Xinbing; ZHANG Yinfeng; RAO Zhengang; DENG Tengfei

    2015-01-01

    Mullite ceramic, as one of high-performance thermal storage ceramics for solar thermal power generation systems, wasin-situ fabricated with talc as a sintering aid via semi-dry pressing and pressureless sintering in air. The mullitization influence of talc as a sintering aid on the formation of andalusite was investigated, and its mechanism to promote the sintering densification of samples was analyzed. The results show that talc reacts with corundum at a low temperature toin-situ produce cordierite. Cordierite reactsin-situ to produce mullite and glass phase, which reduces the sintering temperature sharply when corundum reacts with rich silicon fluid directly and generates secondary mullite. Cordierite resolves and produces magnesium oxide liquid phase, which contains active aluminium oxide lattice capable of reducing reaction activation energy and promoting remaining corundum to react with rich silicon fluid and produces secondary mullite.

  19. Sintering Densification Mechanism of Talc on Promoting Thermal Storage Andalusite Ceramics in Solar Thermal Power Generation

    Institute of Scientific and Technical Information of China (English)

    WU; Jianfeng; CHENG; Hao; XU; Xiaohong; LAO; Xinbing; ZHANG; Yinfeng; RAO; Zhengang; DENG; Tengfei

    2015-01-01

    Mullite ceramic,as one of high-performance thermal storage ceramics for solar thermal power generation systems,was in-situ fabricated with talc as a sintering aid via semi-dry pressing and pressureless sintering in air.The mullitization influence of talc as a sintering aid on the formation of andalusite was investigated,and its mechanism to promote the sintering densification of samples was analyzed.The results show that talc reacts with corundum at a low temperature to in-situ produce cordierite.Cordierite reacts in-situ to produce mullite and glass phase,which reduces the sintering temperature sharply when corundum reacts with rich silicon fluid directly and generates secondary mullite.Cordierite resolves and produces magnesium oxide liquid phase,which contains active aluminium oxide lattice capable of reducing reaction activation energy and promoting remaining corundum to react with rich silicon fluid and produces secondary mullite.

  20. Mechanical Testing of Carbon Based Woven Thermal Protection Materials

    Science.gov (United States)

    Pham, John; Agrawal, Parul; Arnold, James O.; Peterson, Keith; Venkatapathy, Ethiraj

    2013-01-01

    Three Dimensional Woven thermal protection system (TPS) materials are one of the enabling technologies for mechanically deployable hypersonic decelerator systems. These materials have been shown capable of serving a dual purpose as TPS and as structural load bearing members during entry and descent operations. In order to ensure successful structural performance, it is important to characterize the mechanical properties of these materials prior to and post exposure to entry-like heating conditions. This research focuses on the changes in load bearing capacity of woven TPS materials after being subjected to arcjet simulations of entry heating. Preliminary testing of arcjet tested materials [1] has shown a mechanical degradation. However, their residual strength is significantly more than the requirements for a mission to Venus [2]. A systematic investigation at the macro and microstructural scales is reported here to explore the potential causes of this degradation. The effects of heating on the sizing (an epoxy resin coating used to reduce friction and wear during fiber handling) are discussed as one of the possible causes for the decrease in mechanical properties. This investigation also provides valuable guidelines for margin policies for future mechanically deployable entry systems.

  1. Thermal-mechanical modeling of laser ablation hybrid machining

    Science.gov (United States)

    Matin, Mohammad Kaiser

    2001-08-01

    Hard, brittle and wear-resistant materials like ceramics pose a problem when being machined using conventional machining processes. Machining ceramics even with a diamond cutting tool is very difficult and costly. Near net-shape processes, like laser evaporation, produce micro-cracks that require extra finishing. Thus it is anticipated that ceramic machining will have to continue to be explored with new-sprung techniques before ceramic materials become commonplace. This numerical investigation results from the numerical simulations of the thermal and mechanical modeling of simultaneous material removal from hard-to-machine materials using both laser ablation and conventional tool cutting utilizing the finite element method. The model is formulated using a two dimensional, planar, computational domain. The process simulation acronymed, LAHM (Laser Ablation Hybrid Machining), uses laser energy for two purposes. The first purpose is to remove the material by ablation. The second purpose is to heat the unremoved material that lies below the ablated material in order to ``soften'' it. The softened material is then simultaneously removed by conventional machining processes. The complete solution determines the temperature distribution and stress contours within the material and tracks the moving boundary that occurs due to material ablation. The temperature distribution is used to determine the distance below the phase change surface where sufficient ``softening'' has occurred, so that a cutting tool may be used to remove additional material. The model incorporated for tracking the ablative surface does not assume an isothermal melt phase (e.g. Stefan problem) for laser ablation. Both surface absorption and volume absorption of laser energy as function of depth have been considered in the models. LAHM, from the thermal and mechanical point of view is a complex machining process involving large deformations at high strain rates, thermal effects of the laser, removal of

  2. Unique mechanical properties of nanostructured transparent MgAl2O4 ceramics.

    Science.gov (United States)

    Zhang, Jie; Lu, Tiecheng; Chang, Xianghui; Wei, Nian; Qi, Jianqi

    2013-06-01

    Nanoindentation tests were performed on nanostructured transparent magnesium aluminate (MgAl2O4) ceramics to determine their mechanical properties. These tests were carried out on samples at different applied loads ranging from 300 to 9,000 μN. The elastic recovery for nanostructured transparent MgAl2O4 ceramics at different applied loads was derived from the force-depth data. The results reveal a remarkable enhancement in plastic deformation as the applied load increases from 300 to 9,000 μN. After the nanoindetation tests, scanning probe microscope images show no cracking in nanostructured transparent MgAl2O4 ceramics, which confirms the absence of any cracks and fractures around the indentation. Interestingly, the flow of the material along the edges of indent impressions is clearly presented, which is attributed to the dislocation introduced. High-resolution transmission electron microscopy observation indicates the presence of dislocations along the grain boundary, suggesting that the generation and interaction of dislocations play an important role in the plastic deformation of nanostructured transparent ceramics. Finally, the experimentally measured hardness and Young's modulus, as derived from the load-displacement data, are as high as 31.7 and 314 GPa, respectively.

  3. Algebraic roots of Newtonian mechanics: correlated dynamics of particles on a unique worldline

    Science.gov (United States)

    Kassandrov, Vladimir V.; Khasanov, Ildus Sh

    2013-05-01

    In the development of the old ideas of Stueckelberg-Wheeler-Feynman on the ‘one-electron Universe’, we study the purely algebraic dynamics of the ensemble of (two kinds of) identical point-like particles. These are represented by the (real and complex conjugate) roots of a generic polynomial system of equations that implicitly defines a single ‘worldline’. The dynamics includes events of ‘merging’ of a pair of particles modelling the annihilation/creation processes. Correlations in the location and motion of the particles-roots relate, in particular, to the Vieta formulas. After a special choice of the inertial-like reference frame, the linear Vieta formulas guarantee that, for any worldline, the law of (non-relativistic) momentum conservation is identically satisfied. Thus, the general structure of Newtonian mechanics follows from the algebraic properties of a worldline alone. A simple example of, unexpectedly rich, ‘polynomial dynamics’ is retraced in detail and illustrated via an animation (available from stacks.iop.org/JPhysA/46/175206/mmedia).

  4. Thermal relaxation and mechanical relaxation of rice gel

    Institute of Scientific and Technical Information of China (English)

    丁玉琴; 赵思明; 熊善柏

    2008-01-01

    Rice gel was prepared by simulating the production processes of Chinese local rice noodles,and the properties of thermal relaxation and mechanical relaxation during gelatinization were studied by differential scanning calorimetry(DSC) measurement and dynamic rheometer.The results show that during gelatinization,the molecular chains of rice starch undergo the thermal relaxation and mechanical relaxation.During the first heating and high temperature holding processes,the starch crystallites in the rice slurry melt,and the polymer chains stretch and interact,then viscoelastic gel forms.The cooling and low temperatures holding processes result in reinforced networks and decrease the viscoelasticity of the gel.During the second heating,the remaining starch crystallites further melt,the network is reinforced,and the viscoelasticity increases.The viscoelasticity,the molecular conformation and texture of the gel are adjusted by changing the temperature,and finally construct the gel with the textural characteristics of Chinese local rice noodle.

  5. Thermal stability of nafion membranes under mechanical stress

    Energy Technology Data Exchange (ETDEWEB)

    Quintilii, M.; Struis, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The feasibility of adequately modified fluoro-ionomer membranes (NAFION{sup R}) is demonstrated for the selective separation of methanol synthesis products from the raw reactor gas at temperatures around 200{sup o}C. For an economically relevant application of this concept on a technical scale the Nafion membranes should be thin ({approx_equal}10 {mu}m) and thermally stable over a long period of time (1-2 years). In cooperation with industry (Methanol Casale SA, Lugano (CH)), we test the thermal stability of Nafion hollow fibers and supported Nafion thin sheet membranes at temperatures between 160 and 200{sup o}C under mechanical stress by applying a gas pressure difference over the membrane surface ({Delta}P{<=} 40 bar). Tests with the hollow fibers revealed that Nafion has visco-elastic properties. Tests with 50 {mu}m thin Nafion sheets supported by a porous metal carrier at 200{sup o}C and {Delta}P=39 bar showed no mechanical defects over a period of 92 days. (author) 5 figs., 4 refs.

  6. Statistical mechanics of influence maximization with thermal noise

    Science.gov (United States)

    Lynn, Christopher W.; Lee, Daniel D.

    2017-03-01

    The problem of optimally distributing a budget of influence among individuals in a social network, known as influence maximization, has typically been studied in the context of contagion models and deterministic processes, which fail to capture stochastic interactions inherent in real-world settings. Here, we show that by introducing thermal noise into influence models, the dynamics exactly resemble spins in a heterogeneous Ising system. In this way, influence maximization in the presence of thermal noise has a natural physical interpretation as maximizing the magnetization of an Ising system given a budget of external magnetic field. Using this statistical mechanical formulation, we demonstrate analytically that for small external-field budgets, the optimal influence solutions exhibit a highly non-trivial temperature dependence, focusing on high-degree hub nodes at high temperatures and on easily influenced peripheral nodes at low temperatures. For the general problem, we present a projected gradient ascent algorithm that uses the magnetic susceptibility to calculate locally optimal external-field distributions. We apply our algorithm to synthetic and real-world networks, demonstrating that our analytic results generalize qualitatively. Our work establishes a fruitful connection with statistical mechanics and demonstrates that influence maximization depends crucially on the temperature of the system, a fact that has not been appreciated by existing research.

  7. Flue Gas Desulfurization by Mechanically and Thermally Activated Sodium Bicarbonate

    Directory of Open Access Journals (Sweden)

    Walawska Barbara

    2014-09-01

    Full Text Available This paper presents the results of study on structural parameters (particle size, surface area, pore volume and the sorption ability of mechanically and thermally activated sodium bicarbonate. The sorption ability of the modified sorbent was evaluated by: partial and overall SO2 removal efficiency, conversion rate, normalized stoichiometric ratio (NSR. Sodium bicarbonate was mechanically activated by various grinding techniques, using three types of mills: fluid bed opposed jet mill, fine impact mill and electromagnetic mill, differing in grinding technology. Grounded sorbent was thermally activated, what caused a significant development of surface area. During the studies of SO2 sorption, a model gas with a temperature of 300°C, of composition: sulfur dioxide at a concentration of 6292 mg/mn3, oxygen, carbon dioxide and nitrogen as a carrier gas, was used. The best development of surface area and the highest SO2 removal efficiency was obtained for the sorbent treated by electromagnetic grinding, with simultaneous high conversion rate.

  8. Thermal mechanical analysis of applications with internal heat generation

    Science.gov (United States)

    Govindarajan, Srisharan Garg

    control blade, spatial variations in temperature within the control blade occur from the non-uniform heat generation within the BORAL as a result of the non-uniform thermal neutron flux along the longitudinal direction when the control blade is partially withdrawn. There is also variation in the heating profile through the thickness and about the circumferential width of the control blade. Mathematical curve-fits are generated for the non-uniform volumetric heat generation profile caused by the thermal neutron absorption and the functions are applied as heating conditions within a finite element model of the control blade built using the commercial finite element code Abaqus FEA. The finite element model is solved as a fully coupled thermal mechanical problem as in the case of the annular target. The resulting deflection is compared with the channel gap to determine if there is a significant risk of the control blade binding during reactor operation. Hence, this dissertation will consist of two sections. The first section will seek to present the thermal and structural safety analyses of the annular targets for the production of molybdenum-99. Since there hasn't been any detailed, documented, study on these annular targets in the past, the work complied in this dissertation will help to understand the thermal-mechanical behavior and failure margins of the target during in-vessel irradiation. As the work presented in this dissertation provides a general performance analysis envelope for the annular target, the tools developed in the process can also be used as useful references for future analyses that are specific to any reactor. The numerical analysis approach adopted and the analytical models developed, can also be applied to other applications, outside the Mo-99 project domain, where internal heat generation exists such as in electronic components and nuclear reactor control blades. The second section will focus on estimating the thermally induced deflection and hence

  9. Mechanical, thermal insulation, thermal resistance and acoustic absorption properties of geopolymer foam concrete

    OpenAIRE

    Zhang, Z.; Provis, J.L.; A. Reid; Wang, H.

    2015-01-01

    This study reports the synthesis and characterization of geopolymer foam concrete (GFC). A Class F fly ash with partial slag substitution was used for GFC synthesis by mechanical mixing of preformed foam. The GFCs exhibited 28 d compressive strengths ranging from 3 to 48 MPa with demolded densities from 720 to 1600 kg/m3 (105 °C oven-dried densities from 585 to 1370 kg/m3), with the different densities achieved through alteration of the foam content. The thermal conductivity of GFCs was in th...

  10. Computational thermal, chemical, fluid, and solid mechanics for geosystems management.

    Energy Technology Data Exchange (ETDEWEB)

    Davison, Scott; Alger, Nicholas; Turner, Daniel Zack; Subia, Samuel Ramirez; Carnes, Brian; Martinez, Mario J.; Notz, Patrick K.; Klise, Katherine A.; Stone, Charles Michael; Field, Richard V., Jr.; Newell, Pania; Jove-Colon, Carlos F.; Red-Horse, John Robert; Bishop, Joseph E.; Dewers, Thomas A.; Hopkins, Polly L.; Mesh, Mikhail; Bean, James E.; Moffat, Harry K.; Yoon, Hongkyu

    2011-09-01

    This document summarizes research performed under the SNL LDRD entitled - Computational Mechanics for Geosystems Management to Support the Energy and Natural Resources Mission. The main accomplishment was development of a foundational SNL capability for computational thermal, chemical, fluid, and solid mechanics analysis of geosystems. The code was developed within the SNL Sierra software system. This report summarizes the capabilities of the simulation code and the supporting research and development conducted under this LDRD. The main goal of this project was the development of a foundational capability for coupled thermal, hydrological, mechanical, chemical (THMC) simulation of heterogeneous geosystems utilizing massively parallel processing. To solve these complex issues, this project integrated research in numerical mathematics and algorithms for chemically reactive multiphase systems with computer science research in adaptive coupled solution control and framework architecture. This report summarizes and demonstrates the capabilities that were developed together with the supporting research underlying the models. Key accomplishments are: (1) General capability for modeling nonisothermal, multiphase, multicomponent flow in heterogeneous porous geologic materials; (2) General capability to model multiphase reactive transport of species in heterogeneous porous media; (3) Constitutive models for describing real, general geomaterials under multiphase conditions utilizing laboratory data; (4) General capability to couple nonisothermal reactive flow with geomechanics (THMC); (5) Phase behavior thermodynamics for the CO2-H2O-NaCl system. General implementation enables modeling of other fluid mixtures. Adaptive look-up tables enable thermodynamic capability to other simulators; (6) Capability for statistical modeling of heterogeneity in geologic materials; and (7) Simulator utilizes unstructured grids on parallel processing computers.

  11. Tetrodotoxin suppresses thermal hyperalgesia and mechanical allodynia in a rat full thickness thermal injury pain model.

    Science.gov (United States)

    Salas, Margaux M; McIntyre, Matthew K; Petz, Lawrence N; Korz, Walter; Wong, Donald; Clifford, John L

    2015-10-21

    Burn injuries have been identified as the primary cause of injury in 5% of U.S. military personnel evacuated from Operations Iraqi Freedom and Enduring Freedom. Severe burn-associated pain is typically treated with opioids such as fentanyl, morphine, and methadone. Side effects of opioids include respiratory depression, cardiac depression, decrease in motor and cognitive function, as well as the development of hyperalgesia, tolerance and dependence. These effects have led us to search for novel analgesics for the treatment of burn-associated pain in wounded combat service members. Tetrodotoxin (TTX) is a selective voltage-gated sodium channel blocker currently in clinical trials as an analgesic. A phase 3 clinical trial for cancer-related pain has been completed and phase 3 clinical trials on chemotherapy-induced neuropathic pain are planned. It has also been shown in mice to inhibit the development of chemotherapy-induced neuropathic pain. TTX was originally identified as a neurotoxin in marine animals but has now been shown to be safe in humans at therapeutic doses. The antinociceptive effects of TTX are thought to be due to inhibition of Na(+) ion influx required for initiation and conduction of nociceptive impulses. One TTX sensitive sodium channel, Nav1.7, has been shown to be essential in lowering the heat pain threshold after burn injuries. To date, the analgesic effect of TTX has not been tested in burn-associated pain. Male Sprague-Dawley rats were subjected to a full thickness thermal injury on the right hind paw. TTX (8 μg/kg) was administered once a day systemically by subcutaneous injection beginning 3 days post thermal injury and continued through 7 days post thermal injury. Thermal hyperalgesia and mechanical allodynia were assessed 60 and 120 min post injection on each day of TTX treatment. TTX significantly reduced thermal hyperalgesia at all days tested and had a less robust, but statistically significant suppressive effect on mechanical

  12. Microcracking in composite laminates under thermal and mechanical loading. Thesis

    Science.gov (United States)

    Maddocks, Jason R.

    1995-01-01

    Composites used in space structures are exposed to both extremes in temperature and applied mechanical loads. Cracks in the matrix form, changing the laminate thermoelastic properties. The goal of the present investigation is to develop a predictive methodology to quantify microcracking in general composite laminates under both thermal and mechanical loading. This objective is successfully met through a combination of analytical modeling and experimental investigation. In the analysis, the stress and displacement distributions in the vicinity of a crack are determined using a shear lag model. These are incorporated into an energy based cracking criterion to determine the favorability of crack formation. A progressive damage algorithm allows the inclusion of material softening effects and temperature-dependent material properties. The analysis is implemented by a computer code which gives predicted crack density and degraded laminate properties as functions of any thermomechanical load history. Extensive experimentation provides verification of the analysis. AS4/3501-6 graphite/epoxy laminates are manufactured with three different layups to investigate ply thickness and orientation effects. Thermal specimens are cooled to progressively lower temperatures down to -184 C. After conditioning the specimens to each temperature, cracks are counted on their edges using optical microscopy and in their interiors by sanding to incremental depths. Tensile coupons are loaded monotonically to progressively higher loads until failure. Cracks are counted on the coupon edges after each loading. A data fit to all available results provides input parameters for the analysis and shows them to be material properties, independent of geometry and loading. Correlation between experiment and analysis is generally very good under both thermal and mechanical loading, showing the methodology to be a powerful, unified tool. Delayed crack initiation observed in a few cases is attributed to a

  13. Affleck-Dine mechanism with negative thermal logarithmic potential

    CERN Document Server

    Kasuya, S; Takahashi, F; Takahashi, Fuminobu

    2003-01-01

    We investigate whether the Affleck-Dine (AD) mechanism works when the contribution of the two-loop thermal correction to the potential is negative in the gauge-mediated supersymmetry breaking models. The AD field is trapped far away from the origin by the negative thermal correction for a long time until the temperature of the universe becomes low enough. The most striking feature is that the Hubble parameter becomes much smaller than the mass scale of the radial component of the AD field, during the trap. Then, the amplitude of the AD field decreases so slowly that the baryon number is not fixed even after the onset of radial oscillation. The resultant baryon asymmetry crucially depends on whether the Hubble parameter, $H$, is larger than the mass scale of the phase component of the AD field, $M_\\theta$, at the beginning of oscillation. If $H M_\\theta$ holds, it is found that the dynamics of Q-ball formation does not affect the baryon asymmetry, and that it is possible to generate the right amount of the ba...

  14. Mechanical, Thermal and Functional Properties of Green Lightweight Foamcrete

    Directory of Open Access Journals (Sweden)

    Md Azree Othuman Mydin

    2012-09-01

    Full Text Available In recent times, the construction industry has revealed noteworthy attention in the use of lightweight foamcrete as a building material due to its many favourable characteristics such as lighter weight, easy to fabricate, durable and cost effective. Foamcrete is a material consisting of Portland cement paste or cement filler matrix (mortar with a homogeneous pore structure created by introducing air in the form of small bubbles. With a proper control in dosage of foam and methods of production, a wide range of densities (400 – 1600 kg/m 3 of foamcrete can be produced thus providing flexibility for application such as structural elements, partition, insulating materials and filling grades. Foamcrete has so far been applied primarily as a filler material in civil engineering works. However, its good thermal and acoustic performance indicates its strong potential as a material in building construction. The focus of this paper is to classify literature on foamcrete in terms of its mechanical, thermal and functional properties.

  15. Mechanism of NO reduction with non-thermal plasma

    Institute of Scientific and Technical Information of China (English)

    YU Gang; YU Qi; JIANG Yan-long; ZENG Ke-si; GU Fan

    2005-01-01

    Non-thermal plasma has been proved to be an effective and competitive technology for removing NO in flue gas since 1970. In this paper, the NO reduction mechanism of the non-thermal plasma reaction in NO/N2/O2 system was investigated using the method of spectral analysis and quantum chemistry. By the establishment of NO reduction and gas discharge plasma emission spectrum measuring system, the NO reduction results, gas discharge emission spectra of NO/N2O2 and pure N2 were obtained, and then the model of molecular orbit of N2 either in ground state or its excited state was worked out using the method of molecular orbit Ab initio in SelfConsistent Field(SCF). It was found that NO reduction in NO/N2 gas discharge plasma was achieved mainly through a series of fast elementary reactions and the N(E6) at excited state was the base for NO reduction.

  16. Cellulose-Templated Graphene Monoliths with Anisotropic Mechanical, Thermal, and Electrical Properties.

    Science.gov (United States)

    Zhang, Rujing; Chen, Qiao; Zhen, Zhen; Jiang, Xin; Zhong, Minlin; Zhu, Hongwei

    2015-09-02

    Assembling particular building blocks into composites with diverse targeted structures has attracted considerable interest for understanding its new properties and expanding the potential applications. Anisotropic organization is considered as a frequently used targeted architecture and possesses many peculiar properties because of its unusual shapes. Here, we show that anisotropic graphene monoliths (AGMs), three-dimensional architectures of well-aligned graphene sheets obtained by a dip-coating method using cellulose acetate fibers as templates show thermal-insulating, fire-retardant, and anisotropic properties. They exhibit a feature of higher mechanical strength and thermal/electrical conductivities in the axial direction than in the radial direction. Elastic polymer resins are then introduced into the pores of the AGMs to form conductive and flexible composites. The composites, as AGMs, retain the unique anisotropic properties, revealing opposite resistance change under compressions in different directions. The outstanding anisotropic properties of AGMs make them possible to be applied in the fields of thermal insulation, integrated circuits, and electromechanical devices.

  17. Lattice Mismatch Dominant Yet Mechanically Tunable Thermal Conductivity in Bilayer Heterostructures.

    Science.gov (United States)

    Gao, Yuan; Liu, Qingchang; Xu, Baoxing

    2016-05-24

    Heterostructures that are assembled by interfacing two-dimensional (2D) materials offer a unique platform for the emerging devices with unprecedented functions. The attractive functions in heterostructures that are usually absent and beyond the single layer 2D materials are largely affected by the inherent lattice mismatch between layers. Using nonequilibrium molecular dynamics simulations, we show that the phonon thermal transport in the graphene-MoS2 bilayer heterostructure is reduced by the lattice mismatch, and the reduction can be mitigated well by an external tension, weakening the effect of inherent mismatch-induced strain on thermal conductivity. Mechanical analysis in each layered component indicates that the external tension will alleviate the lattice mismatch-induced deformation. The phonon spectra are also softened by the applied tension with a significant shift of frequency from high to low modes. A universal theory is proposed to quantitatively predict the role of the lattice mismatch in thermal conductivity of various bilayer heterostructures and shows good agreement with simulations.

  18. Thermal and Quantum Mechanical Noise of a Superfluid Gyroscope

    Science.gov (United States)

    Chui, Talso; Penanen, Konstantin

    2004-01-01

    A potential application of a superfluid gyroscope is for real-time measurements of the small variations in the rotational speed of the Earth, the Moon, and Mars. Such rotational jitter, if not measured and corrected for, will be a limiting factor on the resolution potential of a GPS system. This limitation will prevent many automation concepts in navigation, construction, and biomedical examination from being realized. We present the calculation of thermal and quantum-mechanical phase noise across the Josephson junction of a superfluid gyroscope. This allows us to derive the fundamental limits on the performance of a superfluid gyroscope. We show that the fundamental limit on real-time GPS due to rotational jitter can be reduced to well below 1 millimeter/day. Other limitations and their potential mitigation will also be discussed.

  19. Thermal, dynamic mechanical, and dielectric analyses of some polyurethane biocomposites.

    Science.gov (United States)

    Macocinschi, Doina; Filip, Daniela; Vlad, Stelian; Cristea, Mariana; Musteata, Valentina; Ibanescu, Sorin

    2012-08-01

    Polymer biocomposites based on segmented poly(ester urethane) and extracellular matrix components have been prepared for the development of tissue engineering applications with improved biological characteristics of the materials in contact with blood and tissues for long periods. Thermal, dynamical, and dielectrical analyses were employed to study the molecular dynamics of these materials and the influence of changing the physical network morphology and hydrogen bond interactions accompanied by phase transitions, interfacial effects, and polarization or conductivity. All phenomena that concur in the tested materials are evaluated by cross-examination of the dynamic mechanical characteristic properties (storage modulus, loss modulus, and loss factor) and dielectric properties (relative permittivity, relative loss factor, and loss tangent) as a function of temperature. Comparative aspects were elucidated by calculating the apparent activation energies of multiplex experiments.

  20. Thermal and mechanical behavior of flame retardant epoxy-polyesterurethane blends

    Science.gov (United States)

    Patel, R. H.; Hirani, A. V.; Kachhia, P. H.

    2016-05-01

    Polyesterurethanes are used in different applications due to their unique combination of the properties like toughness, flexibility, solvent resistance, etc. Nowadays flame retardant properties of polymers are of commercial interest because of their potential use in high performance applications. In the present study attempts have been taken to improve the flame retardant properties of conventional epoxy resin by incorporating phosphorus based polyesterurethane. Polyesterurethane has been synthesized in the laboratory and characterized by chemical and instrumental analysis techniques. Thermal stability and char value of the blends have been determined using thermogravimetric analysis technique. Limiting Oxygen Index (LOI) and UL-94 test methods have been used to determine the flame retardant properties of neat polymer and their blends in film form. Mechanical properties like tensile strength, elongation and impact resistance of the blends have been found out. Polyblend of epoxy resin with phosphorus based polyesterurethane has improved flame retardant properties compare to neat epoxy resin.

  1. The thermal and mechanical properties of electron beam-irradiated polylactide

    Energy Technology Data Exchange (ETDEWEB)

    Kuk, In Seol; Jung, Chan Hee; Hwang, In Tae; Choi, Jae Hak; Nho, Young Chang [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2010-06-15

    The effect of electron beam irradiation on the thermal and mechanical properties of polylactide (PLA) was investigated in this research. PLA films were irradiated by electron beams at different absorption doses ranging from 20 to 200 kGy. The thermal and mechanical properties of the irradiated PLA films were investigated by means of differential scanning calorimeter, thermogravimetric analyzer, universal testing machine, dynamic mechanical analyzer, and thermal mechanical analyzer. The results revealed that the chain scission of the PLA predominated over the crosslinking during the irradiation, which considerably deteriorated the thermal and mechanical properties of the PLA.

  2. Effect of mechanical and thermal loading on boron carbide particles reinforced Al-6061 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Manjunatha, B., E-mail: manjunathab.ait@gmail.com [Department of Mechanical Engineering, Acharya Institute of Technology, Soldevanahalli, Hesaraghatta Main Road, Bangalore 560090 (India); Niranjan, H.B., E-mail: girija_hb@hotmail.com [Department of Mechanical Engineering, Sambhram Institute of Technology, Lakshmipura Cross, MS Palya, Jalahalli East, Bangalore 560097 (India); Satyanarayana, K.G., E-mail: gundsat42@hotmail.com [Poornaprajna Institute of Scientific Research (PPISR), Sy. No. 167, Poornaprajnapura, Bidalur Post, Devanahalli, Bangalore 562110, Karnataka (India)

    2015-04-24

    Metal Matrix Composites (MMC) considered as one of the ‘advanced materials’ have evoked growing interest during the last three decades due to their high performance and applications in strategic sectors. These composites exhibit unique and attractive properties over the monolithic alloys, but suffer from low ductility, which makes them not so attractive for some of the applications where high toughness is one of the design criteria. This limitation of MMCs has been overcome by resorting to various treatments such as mechanical and thermal loading. Considering very limited reports available on Al alloy reinforced with boron carbide (B{sub 4}C) particles, this paper presents (i) preparation of Al-6061 alloy reinforced with 1.5–10 wt% B{sub 4}C, (ii) subjecting them to mechanical and thermal treatments and (iii) characterization of all the above samples. Specific ultimate tensile strength and hardness of all the composites were higher than those of matrix. Also, these values increased with increasing amount of particles, with composites containing 8 wt% B{sub 4}C showing the maximum values in all the three conditions. These observations are supported by the uniform distribution of particles in the matrix as observed in their microstructure.

  3. Sapacitabine, the prodrug of CNDAC, is a nucleoside analog with a unique action mechanism of inducing DNA strand breaks

    Institute of Scientific and Technical Information of China (English)

    Xiao-Jun Liu; Billie Nowak; Ya-Qing Wang; William Plunkett

    2012-01-01

    Sapacitabine is an orally bioavailable prodrug of the nucleoside analog 2'-C-cyano-2'-deoxy-1-β-D-arabino-pentofuranosylcytosine (CNDAC).Both the prodrug and active metabolite are in clinical trials for hematologic malignancies and/or solid tumors.CNDAC has a unique mechanism of action:after incorporation into DNA,it induces single-strand breaks (SSBs) that are converted into double-strand breaks (DSBs) when cells go through a second S phase.In our previous studies,we demonstrated that CNDAC-induced SSBs can be repaired by the transcription-coupled nucleotide excision repair pathway,whereas lethal DSBs are mainly repaired through homologous recombination.In the current work,we used clonogenic assays to compare the DNA damage repair mechanism of CNDAC with two other deoxycytidine analogs:cytarabine,which is used in hematologic malignacies,and gemcitabine,which shows activity in solid tumors.Deficiency in two Rad51 paralogs,Rad51D and XRCC3,greatly sensitized cells to CNDAC,but not to cytarabine or gemcitabine,indicating that homologous recombination is not a major mechanism for repairing damage caused by the latter two analogs.This study further suggests clinical activity and application of sapacitabine that is distinct from that of cytarabine or gemcitabine.

  4. Peptide Formation Mechanism on Montmorillonite Under Thermal Conditions

    Science.gov (United States)

    Fuchida, Shigeshi; Masuda, Harue; Shinoda, Keiji

    2014-02-01

    The oligomerization of amino acids is an essential process in the chemical evolution of proteins, which are precursors to life on Earth. Although some researchers have observed peptide formation on clay mineral surfaces, the mechanism of peptide bond formation on the clay mineral surface has not been clarified. In this study, the thermal behavior of glycine (Gly) adsorbed on montmorillonite was observed during heating experiments conducted at 150 °C for 336 h under dry, wet, and dry-wet conditions to clarify the mechanism. Approximately 13.9 % of the Gly monomers became peptides on montmorillonite under dry conditions, with diketopiperazine (cyclic dimer) being the main product. On the other hand, peptides were not synthesized in the absence of montmorillonite. Results of IR analysis showed that the Gly monomer was mainly adsorbed via hydrogen bonding between the positively charged amino groups and negatively charged surface sites (i.e., Lewis base sites) on the montmorillonite surface, indicating that the Lewis base site acts as a catalyst for peptide formation. In contrast, peptides were not detected on montmorillonite heated under wet conditions, since excess water shifted the equilibrium towards hydrolysis of the peptides. The presence of water is likely to control thermodynamic peptide production, and clay minerals, especially those with electrophilic defect sites, seem to act as a kinetic catalyst for the peptide formation reaction.

  5. Unique Charge Storage Characteristics of FEP/THV/FEP Sandwich Electret Membrane Polarized by Thermally Charging Technology

    Science.gov (United States)

    Chen, Gang-Jin; Lei, Ming-Feng; Xiao, Hui-Ming; Wu, Ling

    2014-12-01

    Utilizing the synergy of three processes (space charge injection, dipole orientation and interfacial polarization) which determine the electret properties, a sandwich electret membrane FEP/THV/FEP (FEP: fluorinated ethylene propylene, THV: tetrafluoroethylene-hexafluoropropylene-vinylidene) is prepared by the laminating method and the thermal charging technology. The surface potential measurement indicates that the sandwich electret membrane exhibits excellent charge storage stability. When washing the sample surface with alcohol, its surface potential first undergoes decay to zero, and then quickly restores to a high value. The surface potential value is associated with the charging electric field and temperature. The best charging condition is 18.75 MV·m-1 and 130°C. A charge storage profile is proposed, and the experimental results are in good agreement with this profile.

  6. ATS-6 engineering performance report. Volume:Program and systems summaries: Mechanical and thermal details

    Science.gov (United States)

    Wales, R. O. (Editor)

    1981-01-01

    The overall mission and spacecraft systems, testing, and operations are summarized. The mechanical subsystems are reviewed, encompassing mechanical design requirements; separation and deployment mechanisms; design and performance evaluation; and the television camera reflector monitor. Thermal control and contamination are discussed in terms of thermal control subsystems, design validation, subsystems performance, the advanced flight experiment, and the quartz-crystal microbalance contamination monitor.

  7. Effect of thermal-treatment sequence on sound absorbing and mechanical properties of porous sound-absorbing/thermal-insulating composites

    Directory of Open Access Journals (Sweden)

    Huang Chen-Hung

    2016-01-01

    Full Text Available Due to recent rapid commercial and industrial development, mechanical equipment is supplemented massively in the factory and thus mechanical operation causes noise which distresses living at home. In livelihood, neighborhood, transportation equipment, jobsite construction noises impact on quality of life not only factory noise. This study aims to preparation technique and property evaluation of porous sound-absorbing/thermal-insulating composites. Hollow three-dimensional crimp PET fibers blended with low-melting PET fibers were fabricated into hollow PET/low-melting PET nonwoven after opening, blending, carding, lapping and needle-bonding process. Then, hollow PET/low-melting PET nonwovens were laminated into sound-absorbing/thermal-insulating composites by changing sequence of needle-bonding and thermal-treatment. The optimal thermal-treated sequence was found by tensile strength, tearing strength, sound-absorbing coefficient and thermal conductivity coefficient tests of porous composites.

  8. New numerical model for thermal quenching mechanism in quartz based on two-stage thermal stimulation of thermoluminescence model

    Directory of Open Access Journals (Sweden)

    Ahmed Kadari

    2015-11-01

    Full Text Available The effect of thermal quenching plays an important role in the thermoluminescence (TL of quartz on which many applications of TL are based. The studies of the stability and kinetics of the 325 °C thermoluminescence peak in quartz are described by Wintle (1975, which show the occurrence of thermal quenching, the decrease in luminescence efficiency with rise in temperature. The thermal quenching of thermoluminescence in quartz was studied experimentally by several authors. The simulations work presented in the literature is based on the single-stage thermal stimulation model of thermoluminescence, in spite of that the mechanisms of this effect remain incomplete. This paper presents a new numerical model for thermal quenching in quartz, using the previously published two-stage thermal stimulation of thermoluminescence model.

  9. Thermal-mechanical coupled effect on fracture mechanism and plastic characteristics of sandstone

    Institute of Scientific and Technical Information of China (English)

    ZUO; JianPing; XIE; HePing; ZHOU; HongWei; PENG; SuPing

    2007-01-01

    Scanning electronic microscopy (SEM) was employed to investigate fractographs of sandstone in mine roof strata under thermal-mechanical coupled effect. Based on the evolution of sandstone surface morphology in the failure process and fractography, the fracture mechanism was studied and classified under meso and micro scales, respectively. The differences between fractographs under different temperatures were examined in detail. Under high temperature, fatigue fracture and plastic deformation occurred in the fracture surface. Therefore, the temperature was manifested by these phenomena to influence strongly on micro failure mechanism of sandstone. In addition, the failure mechanism would transit from brittle failure mechanism at low temperature to coupled brittle-ductile failure mechanism at high temperature. The variation of sandstone strength under different temperature can be attributed to the occurrence of plastic deformation, fatigue fracture, and microcracking. The fatigue striations in the fracture surfaces under high temperature may be interpreted as micro fold. And the coupled effect of temperature and tensile stress may be another formation mechanism of micro fold in geology.

  10. Dynamic gas slippage: A unique dual-mechanism approach to the flow of gas in tight formations

    Energy Technology Data Exchange (ETDEWEB)

    Ertekin; King, G.R.; Schwerer, F.C.

    1983-10-01

    A mathematical formulation, applicable to both numerical simulation and transient well analysis, describing the flow of gas in very tight (k < 0.1 md) porous media has been developed. Unique to this formulation is the dual-mechanism transport of gas. In this formulation gas is assumed to be traveling under the influence of two fields: a concentration field and a pressure field. Transport through the concentration field is a Knudsen flow process and is modeled with Fick's Law of diffusion. Transport through the pressure field is a laminar process and is modeled with Darcy's law (inertial-turbulent effects are ignored). The combination of these two flow mechanisms rigorously yields a composition, pressure and saturation dependent slippage factor. The pressure dependence arises from treating the gas as a real gas. The dynamic slippage derived from this formulation is found to be most applicable in reservoirs with permeabilities less than or equal to 0.01 md. The results from this study indicate that in reservoirs of this type, differences between recoveries after ten years of production using the dynamic slip described in this paper and constant slip approaches were as great as 10% depending on the initial gas saturation. If an economic production rate is considered, differences as great as 30 can be expected.

  11. Systematic study of aggregation structure and thermal behavior of a series of unique H-shape alkane molecules.

    Science.gov (United States)

    Yamamoto, Hiroko; Tashiro, Kohji; Nemoto, Norio; Motoyama, Yukihiro; Takahashi, Yoshiaki

    2011-08-11

    The H-shape alkanes of various arm lengths have been synthesized successfully through the Grignard reaction. The detailed investigation of these novel compounds may allow us to widen the topological chemistry field furthermore. The molecular form and molecular packing structure in the crystal lattice have been revealed successfully on the basis of X-ray structure analysis as well as the analysis of Raman longitudinal acoustic modes (LAM) sensitive to the alkyl zigzag chain segments. The molecular conformation in the crystal lattice is deformed markedly from the originally imagined H-shape. In the cases of C3HOH to C6HOH, for example, the molecules are packed in a complicated manner and the OH···O hydrogen bonds govern the whole intermolecular interactions mainly. Since the alkyl segmental length is not very long, the conformational change is not very drastic, i.e., the small configurational entropy. Synergic effect of the hydrogen bonds and the small configurational entropy gives the higher melting point as known from the thermal data. On the other hand, in the cases of C10HOH and C12HOH, one of the long alkyl chain arms is found to be bent by 90° so that all of the alky chain segments of planar-zigzag conformation can be packed as closely as possible, and the intermolecular OH···O hydrogen bonds are also formed effectively without any mistake. As a result, the contribution of nonbonded intra- and intermolecular van der Waals interactions between the trans-zigzag alkyl chain segments become major, and the coupling of this enthalpy effect with the larger configurational entropy effect of the molecular shape results in the decrement of the melting point which approaches gradually that of longer n-alkane compound. In this way a sensitive balance between the nonbonded van der Waals interactions, the OH···O hydrogen bonds, as well as the configurational entropy effect gives the characteristic thermal behavior of the H-shape compounds. The thus

  12. Polycrystalline Si films with unique microstructures formed from amorphous Si films by non-thermal equilibrium flash lamp annealing

    Energy Technology Data Exchange (ETDEWEB)

    Ohdaira, Keisuke; Nishikawa, Takuya; Shiba, Kazuhiro; Takemoto, Hiroyuki; Matsumura, Hideki [School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), Ishikawa (Japan)

    2010-04-15

    Flash lamp annealing (FLA), with millisecond-order duration, can crystallize amorphous silicon (a-Si) films a few {mu}m thick on glass substrates, resulting in formation of polycrystalline Si (poly-Si) films with unprecedented periodic microstructures. The characteristic microstructure, formed spontaneously during crystallization, consists of large-grain regions, containing relatively large grains more than 100 nm in size, and fine-grain regions, including only 10-nm-sized fine grains. The microstructures results from explosive crystallization (EC), driven by heat generation corresponding to the difference of the enthalpies of meta-stable a-Si and stable crystalline Si(c-Si) states, which realizes lateral crystallization velocity on the order of m/s. The lateral crystallization may stop when the temperature of a-Si in the vicinity of c-Si, which is decided by both homogeneous heating from flash irradiation and thermal diffusion from c-Si, falls below a crystallization temperature. This idea is supported by the experimental fact that a lateral crystallization length decreases with decreasing pulse duration. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Physical, Thermal, Magnetic and Mechanical Properties of ARAA

    Energy Technology Data Exchange (ETDEWEB)

    Chun, Y. B.; Lee, D. W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Rhee, C. K. [National Fusion Research Institute, Daejeon, (Korea, Republic of)

    2015-10-15

    The mechanical properties of total ninety-eight model alloys designed for application to HCCR TBM in the ITER were evaluated. The addition of small amounts of Zr was found to have positive effects on creep and impact resistance, based on which Zr-containing reduced activation ferritic-martensitic steel, ARAA, has been developed. A 5-ton scale ARAA was produced via VIM and ESR methods and its basic properties required for fusion reactor applications were evaluated. It is found that the physical, thermal, magnetic and mechanical properties of ARAA are comparable to those of Eurofer 97. Reduced activation ferritic-martensitic (RAFM) steel is considered a primary candidate for the structural material in a fusion reactor, owing to its good swelling resistance and compatibility with various coolants. Several types of RAFM steels showing good performance have been developed, which include the European Eurofer 97 and the Japanese F82H. For these alloys, an extensive materials database is available. The structural materials for the blanket system is expected to be subjected to high heat-load and operate under high-energy (14 MeV) and high-fluence fusion neutron irradiation. The operational range of temperature for a blanket is limited by the high-temperature creep and low-temperature irradiation embrittlement of the structural material. RAFM steels developed thus far are known to be operable at 350-550 .deg. C. To expand the temperature window and thereby allow for various design options, it is important to develop alloys that are able to withstand high temperature and high-energy neutron irradiation.

  14. Thermal degradation reaction mechanism of xylose: A DFT study

    Science.gov (United States)

    Huang, Jinbao; He, Chao; Wu, Longqin; Tong, Hong

    2016-08-01

    The thermal degradation reaction mechanism of xylose as hemicellulose model compound was investigated by using density functional theory methods M062X with the 6-31++G(d,p) basis set. Eight possible pyrolytic reaction pathways were proposed and the standard kinetic and thermodynamic parameters in all reaction pathways were calculated at different temperatures. In reaction pathway (1), xylose is first transformed into acyclic containing-carbonyl isomer, and then the isomer further decomposes through four possible pyrolysis pathways (1-1)-(1-4). Pathways (2) and (3) depict an immediate ring-opening process through the simultaneous breaking of C-O and C-C bonds. Pathways (4)-(7) describe the pyrolysis processes of various anhydro-xyloses through a direct ring-opening process. Pathway (8) gives the evolutionary process of pyranones. The calculation results show that reaction pathways (1), (2) and (5) are the major reaction channels and reaction pathways (3), (4), and (6)-(8) are the competitive reaction channels in pyrolysis of xylose. The major products of xylose pyrolysis are low molecular products such as 2-furaldehyde, glycolaldehyde, acetaldehyde, methylglyoxal and acetone, and the main competitive products are formaldehyde, formic acid, acetic acid, CO2, CH4, acetol, pyranone, and so on.

  15. Investigation Of Aeroacoustic Mechanisms By Remote Thermal Imaging

    Science.gov (United States)

    Witten, Alan J.; Courville, George E.

    1988-01-01

    A hush house is a hangar-like structure designed to isolate, from the surrounding environment, the noise produced by extended aircraft engine operations during diagnostic testing. While hush houses meet this intended need by suppressing audible noise, they do emit significant subaudible acoustic energy which has caused structural vibrations in nearby facilities. As a first step in mitigating the problems associated with hush house induced vibrations, it is necessary to identify the mechanism responsible for the low frequency acoustic emissions. It was hypothesized that the low frequency acoustic waves are a result of acoustic Cherenkov radiation. This radiation is in the form of a coherent wave produced by the engine exhaust gas flow. The speed of sound in the exhaust gas is quite high as a result of its elevated temperature. Therefore, the gas flow is sonic or subsonic relative to its own sound speed, but is supersonic relative to sound speed in the surrounding cooler air and, as a result, produces acoustic Cherenkov radiation. To confirm this hypothesis, thermographic surveys were conducted to image the thermal structure of the engine exhaust gas within the hush house. In the near-field, these images revealed that the exhaust gases did not behave like a high Reynolds number turbulent jet, but rather, the transition to turbulence is delayed by a suppression in growth of the self-excited instability wave as a result of acoustic Cherenkov radiation.

  16. Mechanical-Electrochemical-Thermal Simulation of Lithium-Ion Cells

    Energy Technology Data Exchange (ETDEWEB)

    Santhanagopalan, Shriram; Zhang, Chao; Sprague, Michael A.; Pesaran, Ahmad

    2016-06-01

    Models capture the force response for single-cell and cell-string levels to within 15%-20% accuracy and predict the location for the origin of failure based on the deformation data from the experiments. At the module level, there is some discrepancy due to poor mechanical characterization of the packaging material between the cells. The thermal response (location and value of maximum temperature) agrees qualitatively with experimental data. In general, the X-plane results agree with model predictions to within 20% (pending faulty thermocouples, etc.); the Z-plane results show a bigger variability both between the models and test-results, as well as among multiple repeats of the tests. The models are able to capture the timing and sequence in voltage drop observed in the multi-cell experiments; the shapes of the current and temperature profiles need more work to better characterize propagation. The cells within packaging experience about 60% less force under identical impact test conditions, so the packaging on the test articles is robust. However, under slow-crush simulations, the maximum deformation of the cell strings with packaging is about twice that of cell strings without packaging.

  17. Genome, transcriptome, and secretome analysis of wood decay fungus postia placenta supports unique mechanisms of lignocellulose conversion

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Diego [Los Alamos National Laboratory; Challacombe, Jean F [Los Alamos National Laboratory; Misra, Monica [Los Alamos National Laboratory; Xie, Gary [Los Alamos National Laboratory; Brettin, Thomas [Los Alamos National Laboratory; Morgenstern, Ingo [CLARK UNIV; Hibbett, David [CLARK UNIV.; Schmoll, Monika [UNIV WIEN; Kubicek, Christian P [UNIV WIEN; Ferreira, Patricia [CIB, CSIC, MADRID; Ruiz - Duenase, Francisco J [CIB, CSIC, MADRID; Martinez, Angel T [CIB, CSIC, MADRID; Kersten, Phil [FOREST PRODUCTS LAB; Hammel, Kenneth E [FOREST PRODUCTS LAB; Vanden Wymelenberg, Amber [U. WISCONSIN; Gaskell, Jill [FOREST PRODUCTS LAB; Lindquist, Erika [DOE JGI; Sabati, Grzegorz [U. WISCONSIN; Bondurant, Sandra S [U. WISCONSIN; Larrondo, Luis F [U. CATHOLICA DE CHILE; Canessa, Paulo [U. CATHOLICA DE CHILE; Vicunna, Rafael [U. CATHOLICA DE CHILE; Yadavk, Jagiit [U. CINCINATTI; Doddapaneni, Harshavardhan [U. CINCINATTI; Subramaniank, Venkataramanan [U. CINCINATTI; Pisabarro, Antonio G [PUBLIC U. NAVARRE; Lavin, Jose L [PUBLIC U. NAVARRE; Oguiza, Jose A [PUBLIC U. NAVARRE; Master, Emma [U. TORONTO; Henrissat, Bernard [CNRS, MARSEILLE; Coutinho, Pedro M [CNRS, MARSEILLE; Harris, Paul [NOVOZYMES, INC.; Magnuson, Jon K [PNNL; Baker, Scott [PNNL; Bruno, Kenneth [PNNL; Kenealy, William [MASCOMA, INC.; Hoegger, Patrik J [GEORG-AUGUST-U.; Kues, Ursula [GEORG-AUGUST-U; Ramaiva, Preethi [NOVOZYMES, INC.; Lucas, Susan [DOE JGI; Salamov, Asaf [DOE JGI; Shapiro, Harris [DOE JGI; Tuh, Hank [DOE JGI; Chee, Christine L [UNM; Teter, Sarah [NOVOZYMES, INC.; Yaver, Debbie [NOVOZYMES, INC.; James, Tim [MCMASTER U.; Mokrejs, Martin [CHARLES U.; Pospisek, Martin [CHARLES U.; Grigoriev, Igor [DOE JGI; Rokhsar, Dan [DOE JGI; Berka, Randy [NOVOZYMES; Cullen, Dan [FOREST PRODUCTS LAB

    2008-01-01

    Brown-rot fungi such as Postia placenta are common inhabitants of forest ecosystems and are also largely responsible for the destructive decay of wooden structures. Rapid depolymerization of cellulose is a distinguishing feature of brown-rot, but the biochemical mechanisms and underlying genetics are poorly understood. Systematic examination of the P. placenta genome, transcriptome and secretome revealed unique extracellular enzyme systems, including an unusual repertoire of extracellular glycoside hydrolases. Genes encoding exocellobiohydrolases and cellulose-binding domains, typical of cellulolytic microbes, are absent in this efficient cellulose-degrading fungus. When P. placenta was grown in medium containing cellulose as sole carbon source, transcripts corresponding to many hemicellulases and to a single putative {beta}-1-4 endoglucanase were expressed at high levels relative to glucose grown cultures. These transcript profiles were confirmed by direct identification of peptides by liquid chromatography-tandem mass spectrometry (LC{center_dot}MSIMS). Also upregulated during growth on cellulose medium were putative iron reductases, quinone reductase, and structurally divergent oxidases potentially involved in extracellular generation of Fe(II) and H202. These observations are consistent with a biodegradative role for Fenton chemistry in which Fe(II) and H202 react to form hydroxyl radicals, highly reactive oxidants capable of depolymerizing cellulose. The P. placenta genome resources provide unparalleled opportunities for investigating such unusual mechanisms of cellulose conversion. More broadly, the genome offers insight into the diversification of lignocellulose degrading mechanisms in fungi. Comparisons to the closely related white-rot fungus Phanerochaete chrysosporium support an evolutionary shift from white-rot to brown-rot during which the capacity for efficient depolymerization of lignin was lost.

  18. Correlation between thermal and mechanical properties of hardened steel treated by nitriding process

    Energy Technology Data Exchange (ETDEWEB)

    Ghrib, T; Yacoubi, N, E-mail: taher.ghrib@yahoo.f [Photothermal Laboratory, I PEIN, 8000 Nabeul (Tunisia)

    2010-03-01

    In this work we have studied the nitriding effect for the 42CrMo4 steel on the evolution of their thermal and mechanical properties. The thermal properties are determined by the 'Photothermal Deflection technique' method. It was shown that the thermal conductivity as well as the thermal diffusivity decreases if the nitrogen fraction in steel increases conversely the microhardness increases with the growth of the nitrogen rate. After, we have correlated the thermal and mechanical properties with an empirical equation that permits to determine the microhardness without its measure.

  19. Mechanisms and Mitigation of CMAS Attack on Thermal Barrier Coatings

    Science.gov (United States)

    Zaleski, Elisa Marie

    As gas turbine engines are driven to operate at higher temperatures to maximize efficiency, components become susceptible to attack by deposits of calcium magnesium alumino-silicate (CMAS) ingested with the intake air. Of particular interest to this work is the degradation of thermal barrier coatings (TBCs) by CMAS. Molten CMAS is known to interact with TBCs both thermochemically, by dissolving the ceramic and reprecipitating it as a new or modified phase, and thermomechanically, by infiltrating the porosity and degrading the strain tolerance. The thermochemical degradation of TBCs was investigated using primarily differential scanning calorimetry (DSC) by comparing the endotherms and exotherms recorded for pure, model silicates to those observed for silicates mixed with various TBC materials including YSZ and GZO. The five ternary silicates studied (CaO-AlO1.5-SiO2) began melting over a relatively narrow range (˜1125-1145°C). Introducing magnesium to the ternary results in higher melting temperatures and only minor changes to the crystallization behavior. Iron decreases the melting temperature, and markedly improves the crystallization kinetics of pure silicate systems, especially absent magnesium. Modification of the crystallization behavior of pure silicates has been proposed in the literature as a mitigation strategy for CMAS. This work utilizes DSC to look for characteristic changes as described above to probe potentially effective TBCs. The addition of YSZ to a quaternary CMAS results in little change to the melting or crystallization in the DSC, despite the dissolution of YSZ into the silicate. In stark contrast, GZO with CMAS generates a significant crystallization exotherm that appears in the DSC immediately after the silicate melts. As the fraction of GZO is increased, the melting endotherm begins to shrink due to the thermal overlap of the melting and crystallization processes. This signifies a rapid reaction, and a potentially useful TBC material for

  20. A Study on the Interaction Mechanism between Thermal Radiation and Materials

    Institute of Scientific and Technical Information of China (English)

    Dehong XIA; Tao YU; Chuangu WU; Qingqing CHANG; Honglei JIAO

    2005-01-01

    From the viewpoint of field synergy principle and dipole radiation theory, the interaction between the incident thermal radiation wave and materials is analyzed to reveal the mechanism of selective absorption of incident thermal radiation. It is shown that the frequency of the incident thermal radiation and the damping constant of damping oscillators in materials are of vital importance for the thermal radiation properties (reflectivity, absorptivity, transmissivity, etc.) of materials.

  1. The mechanism by which fish antifreeze proteins cause thermal hysteresis.

    Science.gov (United States)

    Kristiansen, Erlend; Zachariassen, Karl Erik

    2005-12-01

    Antifreeze proteins are characterised by their ability to prevent ice from growing upon cooling below the bulk melting point. This displacement of the freezing temperature of ice is limited and at a sufficiently low temperature a rapid ice growth takes place. The separation of the melting and freezing temperature is usually referred to as thermal hysteresis, and the temperature of ice growth is referred to as the hysteresis freezing point. The hysteresis is supposed to be the result of an adsorption of antifreeze proteins to the crystal surface. This causes the ice to grow as convex surface regions between adjacent adsorbed antifreeze proteins, thus lowering the temperature at which the crystal can visibly expand. The model requires that the antifreeze proteins are irreversibly adsorbed onto the ice surface within the hysteresis gap. This presupposition is apparently in conflict with several characteristic features of the phenomenon; the absence of superheating of ice in the presence of antifreeze proteins, the dependence of the hysteresis activity on the concentration of antifreeze proteins and the different capacities of different types of antifreeze proteins to cause thermal hysteresis at equimolar concentrations. In addition, there are structural obstacles that apparently would preclude irreversible adsorption of the antifreeze proteins to the ice surface; the bond strength necessary for irreversible adsorption and the absence of a clearly defined surface to which the antifreeze proteins may adsorb. This article deals with these apparent conflicts between the prevailing theory and the empirical observations. We first review the mechanism of thermal hysteresis with some modifications: we explain the hysteresis as a result of vapour pressure equilibrium between the ice surface and the ambient fluid fraction within the hysteresis gap due to a pressure build-up within the convex growth zones, and the ice growth as the result of an ice surface nucleation event at

  2. Coupled Mechanical-Electrochemical-Thermal Analysis of Failure Propagation in Lithium-ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chao; Santhanagopalan, Shriram; Pesaran, Ahmad

    2016-07-28

    This is a presentation given at the 12th World Congress for Computational Mechanics on coupled mechanical-electrochemical-thermal analysis of failure propagation in lithium-ion batteries for electric vehicles.

  3. Geologic, stratigraphic, thermal, and mechanical factors which influence repository design in the bedded salt environment

    Energy Technology Data Exchange (ETDEWEB)

    Ashby, J.P.; Nair, O.; Ortman, D.; Rowe, J.

    1979-12-01

    This report describes the geologic, stratigraphic, thermal, and mechanical considerations applicable to repository design. The topics discussed in the report include: tectonic activity; geologic structure; stratigraphy; rock mechanical properties; and hydrologic properties.

  4. Multiple bilateral lower limb fractures in a 2-year-old child: previously unreported injury with a unique mechanism

    Institute of Scientific and Technical Information of China (English)

    Basant Repswal; Anuj Jain; Sunil Gupta; Aditya Aggarwal; Tushar Kohli; Devendra Pathrot

    2014-01-01

    Fall from height is a common cause of unintentional injuries in children and accounts for 6% of all trauma-related childhood deaths,usually from head injury.We report a case of a 2-year-old child with multiple fractures of the bilateral lower limbs due to this reason.A child fell from a height of around 15 feet after toppling from a balcony.He developed multiple fractures involving the right femoral shaft,right distal femoral epiphysis (Salter Harris type 2),right distal metaphysis of the tibia and fibula,and undisplaced Salter Harris type 2 epiphyseal injury of the left distal tibia.There were no head,abdominal or spinal injuries.The patient was taken into emergency operation theatre after initial management which consisted of intravenous fluids,blood transfusion,and splintage of both lower limbs.Fracture of the femoral shaft was treated by closed reduction and fixation using two titanium elastic nails.Distal femoral physeal injury required open reduction and fixation with K wires.Distal tibia fractures were closely reduced and managed nonoperatively in both the lower limbs.All the fractures united in four weeks.At the last follow-up,the child had no disability and was able to perform daily activities comfortably.We also proposed the unique mechanism of injury in this report.

  5. Multiple bilateral lower limb fractures in a 2-year-old child: previously unreported injury with a unique mechanism

    Directory of Open Access Journals (Sweden)

    Anuj Jain

    2014-10-01

    Full Text Available 【Abstract】Fall from height is a common cause of unintentional injuries in children and accounts for 6% of all trauma-related childhood deaths, usually from head injury. We report a case of a 2-year-old child with multiple fractures of the bilateral lower limbs due to this reason. A child fell from a height of around 15 feet after toppling from a alcony. He developed multiple fractures involving the right femoral shaft, right distal femoral epiphysis (Salter Harris type 2, right distal metaphysis of the tibia and fi bula, and undisplaced Salter Harris type 2 epiphyseal injury of the left distal tibia. There were no head, abdominal or spinal injuries. The patient was taken into emergency operation theatre after initial management which consisted of intravenous fl uids, blood transfusion, and splintage of both lower limbs. Fracture of the femoral shaft was treated by closed reduction and fixation using two titanium elastic nails. Distal femoral physeal injury required open eduction and fixation with K wires. Distal tibia fractures were closely reduced and managed nonoperatively in both the lower limbs. All the fractures united in four weeks. At the last follow-up, the child had no disability and was able to perform daily ctivities comfortably. We also proposed the unique mechanism of injury in this report. Key words: Multiple bilateral lower limb fractures; Fall; Child

  6. Tubuliform silk protein: A protein with unique molecular characteristics and mechanical properties in the spider silk fibroin family

    Science.gov (United States)

    Tian, M.; Lewis, R. V.

    2006-02-01

    Orb-web weavers can produce up to six different types of silk and a glue for various functions. Tubuliform silk is unique among them due to its distinct amino acid composition, specific time of production, and atypical mechanical properties. To study the protein composing this silk, tubuliform gland cDNA libraries were constructed from three orb-weaving spiders Argiope aurantia, Araneus gemmoides, and Nephila clavipes. Amino acid composition comparison between the predicted tubuliform silk protein sequence (TuSp1) and the corresponding gland protein confirms that TuSp1 is the major component in tubuliform gland in three spiders. Sequence analysis suggests that TuSp1 shares no significant similarity with its paralogues, while it has conserved sequence motifs with the most primitive spider, Euagrus chisoseus silk protein. The presence of large side-chain amino acids in TuSp1 sequence is consistent with the frustrated β-sheet crystalline structure of tubuliform silk observed in transmission electron microscopy. Repeat unit comparison within species as well as among three spiders exhibits high sequence conservation. Parsimony analysis based on carboxy terminal sequence shows that Argiope and Araneus are more closely related than either is to Nephila which is consistent with phylogenetic analysis based on morphological evidence.

  7. Exploring A Thermal-Orbital Feedback Mechanism At Europa

    Science.gov (United States)

    Walker, Matthew; Mitchell, Jonathan L.; Bills, Bruce

    2016-10-01

    We present a geophysical model of the Europa system to describe it's structural, orbital, and thermal states. In doing so, we examine the potential for feedback mechanisms to occur which can produce oscillatory behavior in shell thickness, eccentricity, and heat flux, due to the coupled nature of the relevant processes. We implement a tidal heating model to describe the heat flux into the body. This model depends primarily on the shell structure as well as the orbital eccentricity. The model has the capacity to consider multilayered bodies for which the interior structure can evolve over time. Furthermore, the tidal heating model is fully three dimensionally resolved, having the ability to predict radial and lateral variations in heating throughout Europa. This allows us to predict particular locations on Europa that should have the maximum surface heat flux. This heating model is coupled to the orbital evolution as well. Tidal dissipation pulls energy out of the orbit, effectively reducing the semi-major axis and eccentricity, circularizing the orbit. This would slow, and even shut down, the tidal heating at Europa, however, the Galilean Satellites' Laplace resonance continuously transfers energy back into Europa's orbit, keeping the tidal dissipation active. We compare the tidal heat input to the heat conducted out of the ice shell, which is a function of shell thickness, among other things. Heat transfer into or out of the ice compensates any imbalance of heat. This heating, in turn, leads to structural variations of the shell. For example, if tidal heating is greater than the heat conducted out of the shell, the remaining balance goes into sensible and latent heats which thin the shell (thus increasing the surface heat output to balance that which is tidally input). Oppositely, when conducted heat output is greater than the tidal heating, the shell thickens. Shell thickness variations then result in global extension or contraction, due to the density difference

  8. Preliminary Thermal Mechanical Analysis of the Equatorial Thermal Shield for ITER

    Institute of Scientific and Technical Information of China (English)

    雷明准; 宋云涛; 杜世俊; 叶民友; 奚维斌; 刘旭峰

    2012-01-01

    Thermal analysis of the equatorial thermal shield for ITER is conducted in order to confirm that the cooling tube design was reasonable under both the plasma operational and the baking operational conditions. The structural performance was analyzed by means of the finite element software ANSYS. A comparison of the results with design requirements shows that the results of the simulation are within allowable design requirements, which indicates the feasibility and reliability of the equatorial thermal shield structure.

  9. Scientific Basis for a Coupled Thermal-Hydrological-Mechanical-Chemical-Biological Experimental Facility at DUSEL Homestake

    Science.gov (United States)

    Sonnenthal, E. L.; Elsworth, D.; Lowell, R. P.; Maher, K.; Mailloux, B. J.; Uzunlar, N.; Freifeld, B. M.; Keimowitz, A. R.; Wang, J. S.

    2009-12-01

    Most natural and engineered earth system processes involve strong coupling of thermal, mechanical, chemical, and sometimes biological processes in rocks that are heterogeneous at a wide range of spatial scales. One of the most pervasive processes in the Earth’s crust is that of fluids (primarily water, but also CO2, hydrocarbons, volcanic gases, etc.) flowing through fractured heated rock under stress. A preliminary design is being formulated for a large-scale subsurface experimental facility to investigate coupled Thermal-Hydrological-Mechanical-Chemical-Biological (THMCB) processes in fractured rock at depth. The experiment would be part of the proposed Deep Underground Science and Engineering Laboratory (DUSEL) in the Homestake Mine, South Dakota. Fundamental geochemical, isotopic, microbiological, laboratory THMC experiments, and numerical modeling will be used to guide the experimental design and evaluation of the time and spatial scales of the coupled THMCB processes. Although we sometimes analyze rocks and fluids for physical and chemical properties, it is difficult to create quantitative numerical models based on fundamental physics and chemistry that can capture the dynamic changes that have occurred or may yet take place. Initial conditions and history are only known roughly at best, and the boundary conditions have likely varied over time as well. Processes such as multicomponent chemical and thermal diffusion, multiphase flow, advection, and thermal expansion/contraction, are taking place simultaneously in rocks that are structurally and chemically complex—heterogeneous assemblages of mineral grains, pores, and fractures—and visually opaque. The only way to fully understand such processes is to carry out well-controlled experiments at a range of scales (grain/pore-scale to decimeter-scale) that can be interrogated and modeled. The THMCB experimental facility is also intended to be a unique laboratory for testing hypotheses regarding effects of

  10. Lightweight Mechanical Metamaterials with Tunable Negative Thermal Expansion.

    Science.gov (United States)

    Wang, Qiming; Jackson, Julie A; Ge, Qi; Hopkins, Jonathan B; Spadaccini, Christopher M; Fang, Nicholas X

    2016-10-21

    Ice floating on water is a great manifestation of negative thermal expansion (NTE) in nature. The limited examples of natural materials possessing NTE have stimulated research on engineered structures. Previous studies on NTE structures were mostly focused on theoretical design with limited experimental demonstration in two-dimensional planar geometries. In this work, aided with multimaterial projection microstereolithography, we experimentally fabricate lightweight multimaterial lattices that exhibit significant negative thermal expansion in three directions and over a temperature range of 170 degrees. Such NTE is induced by the structural interaction of material components with distinct thermal expansion coefficients. The NTE can be tuned over a large range by varying the thermal expansion coefficient difference between constituent beams and geometrical arrangements. Our experimental results match qualitatively with a simple scaling law and quantitatively with computational models.

  11. Thermal mechanical stress modeling of GCtM seals

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Steve Xunhu [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Chambers, Robert [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    Finite-element thermal stress modeling at the glass-ceramic to metal (GCtM) interface was conducted assuming heterogeneous glass-ceramic microstructure. The glass-ceramics were treated as composites consisting of high expansion silica crystalline phases dispersed in a uniform residual glass. Interfacial stresses were examined for two types of glass-ceramics. One was designated as SL16 glass -ceramic, owing to its step-like thermal strain curve with an overall coefficient of thermal expansion (CTE) at 16 ppm/ºC. Clustered Cristobalite is the dominant silica phase in SL16 glass-ceramic. The other, designated as NL16 glass-ceramic, exhibited clusters of mixed Cristobalite and Quartz and showed a near-linear thermal strain curve with a same CTE value.

  12. Lightweight Mechanical Metamaterials with Tunable Negative Thermal Expansion

    Science.gov (United States)

    Wang, Qiming; Jackson, Julie A.; Ge, Qi; Hopkins, Jonathan B.; Spadaccini, Christopher M.; Fang, Nicholas X.

    2016-10-01

    Ice floating on water is a great manifestation of negative thermal expansion (NTE) in nature. The limited examples of natural materials possessing NTE have stimulated research on engineered structures. Previous studies on NTE structures were mostly focused on theoretical design with limited experimental demonstration in two-dimensional planar geometries. In this work, aided with multimaterial projection microstereolithography, we experimentally fabricate lightweight multimaterial lattices that exhibit significant negative thermal expansion in three directions and over a temperature range of 170 degrees. Such NTE is induced by the structural interaction of material components with distinct thermal expansion coefficients. The NTE can be tuned over a large range by varying the thermal expansion coefficient difference between constituent beams and geometrical arrangements. Our experimental results match qualitatively with a simple scaling law and quantitatively with computational models.

  13. Enhanced mechanical and thermal properties of regenerated cellulose/graphene composite fibers.

    Science.gov (United States)

    Tian, Mingwei; Qu, Lijun; Zhang, Xiansheng; Zhang, Kun; Zhu, Shifeng; Guo, Xiaoqing; Han, Guangting; Tang, Xiaoning; Sun, Yaning

    2014-10-13

    In this study, a wet spinning method was applied to fabricate regenerated cellulose fibers filled with low graphene loading which was systematically characterized by SEM, TEM, FTIR and XRD techniques. Subsequently, the mechanical and thermal properties of the resulting fibers were investigated. With only 0.2 wt% loading of graphene, a ∼ 50% improvement of tensile strength and 25% enhancement of Young's modulus were obtained and the modified Halpin-Tsai model was built to predict the mechanical properties of composite fibers. Thermal analysis of the composite fibers showed remarkably enhanced thermal stability and dynamic heat transfer performance of graphene-filled cellulose composite fiber, also, the presence of graphene oxide can significantly enhance the thermal conductivity of the composite fiber. This work provided a facile way to improve mechanical and thermal properties of regenerated cellulose fibers. The resultant composite fibers have potential application in thermal insulation and reinforced fibrous materials. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Mechanical, Thermal, and Microstructural Analysis of Polyvinyl Alcohol/Montmorillonite Nanocomposites

    Directory of Open Access Journals (Sweden)

    P. G. Allison

    2015-01-01

    Full Text Available Structural biomaterials such as nacre, bone, and fish scales possess unique structures that have hierarchical spatial configurations, which provide excellent mechanical properties when compared to their individual constituents. These observations have been the motivation for designing and characterizing bioinspired materials with high strength, high stiffness, and corrosion-resistant properties while at the same time being environmentally friendly. It has been demonstrated that polymer-clay nanocomposites can simulate the behavior of nacreous biomaterials such as abalone shell. Mechanical, thermal, and microstructural analyses characterized solution-cast polyvinyl alcohol (PVA/montmorillonite (MMT nanocomposite properties over compositions ranging from the neat polymer to 25% volume fraction of MMT nanoclay. Uniaxial tensile experiments were performed at displacement rates of 1 mm/min and 50 mm/min. Strength values are similar to those shown by nacre and represent a homogeneous dispersion of the MMT in the polymer matrix. Strength-to-weight ratios are similar to many structural metals.

  15. Unique lasing mechanism of localized dispersive nanostructures in InAs/InGaAlAs quantum dash broad interband laser

    KAUST Repository

    Tan, C. L.

    2010-02-11

    The authors report on the nanowires-like and nanodots-like lasing behaviors in addition to multiple-wavelength interband transitions from InAs/InAlGaAs quantum dash (Qdash) lasers in the range of ~1550 nm. The presence of lasing actions simultaneously from two different dash ensembles, after postgrowth intermixing for crystalline quality improvement, indicate the absence of optical phonon emission due to the small variation in quantized interband transition energies. This effect is reproducible and shows different lasing characteristics from its quantum dot and quantum wire laser counterparts. Furthermore, the small energy spacing of only 25 nm (at center lasing wavelength of ~1550 nm) and the subsequent quenching of higher energy transition states at higher bias level in Qdash lasers suggest the absence of excited-state transition in highly inhomogeneous self-assembled Qdash structures. However, the appearance of a second lasing line in a certain range of high injection level, which is due to the presence of different sizes of dash assembles, corresponds to the transition from smaller size of Qdash ensembles in different planar active medium. This unique transition mechanism will affect the carrier dynamics, relaxation process in particular and further indicates localized finite carrier lifetime in all sizes of Qdash ensembles. These phenomena will lead to important consequences for the ground-state lasing efficiency and frequency modulation response of Qdash devices. In addition, these imply that proper manipulation of the Qdash ensembles will potentially result in localized nanolasers from individual ensemble and thus contributing towards enormously large envelope lasing coverage from semiconductor devices.

  16. Mitigating thermal mechanical damage potential during two-photon dermal imaging.

    Science.gov (United States)

    Masters, Barry R; So, Peter T C; Buehler, Christof; Barry, Nicholas; Sutin, Jason D; Mantulin, William W; Gratton, Enrico

    2004-01-01

    Two-photon excitation fluorescence microscopy allows in vivo high-resolution imaging of human skin structure and biochemistry with a penetration depth over 100 microm. The major damage mechanism during two-photon skin imaging is associated with the formation of cavitation at the epidermal-dermal junction, which results in thermal mechanical damage of the tissue. In this report, we verify that this damage mechanism is of thermal origin and is associated with one-photon absorption of infrared excitation light by melanin granules present in the epidermal-dermal junction. The thermal mechanical damage threshold for selected Caucasian skin specimens from a skin bank as a function of laser pulse energy and repetition rate has been determined. The experimentally established thermal mechanical damage threshold is consistent with a simple heat diffusion model for skin under femtosecond pulse laser illumination. Minimizing thermal mechanical damage is vital for the potential use of two-photon imaging in noninvasive optical biopsy of human skin in vivo. We describe a technique to mitigate specimen thermal mechanical damage based on the use of a laser pulse picker that reduces the laser repetition rate by selecting a fraction of pulses from a laser pulse train. Since the laser pulse picker decreases laser average power while maintaining laser pulse peak power, thermal mechanical damage can be minimized while two-photon fluorescence excitation efficiency is maximized.

  17. Mechanical spectroscopy of thermal stress relaxation in aluminium alloys reinforced with short alumina fibres

    Energy Technology Data Exchange (ETDEWEB)

    Carreno-Morelli, E.; Schaller, R. [Ecole Polytechnique Federale, Lausanne (Switzerland). Inst. de Genie Atomique; Urreta, S.E.

    1998-05-01

    The mechanical behaviour under low temperature thermal cycling of aluminium-based composites reinforced with short Al{sub 2}O{sub 3} SAFFIL fibres has been investigated by mechanical spectroscopy (mechanical loss and elastic shear modulus measurements). A mechanical loss maximum has been observed during cooling which originates in the relaxation of thermal stresses at the interfaces due to the differential thermal expansion between matrix and reinforcement. The maximum height increases with the volumetric fibre content. In addition, if the matrix strength is increased by the appropriated choice of alloy and thermal treatment, the maximum diminishes and shifts to lower temperatures. No damage accumulation at the interfaces has been detected during long period thermal cycling in the range 100 to 500 K. A description of the damping behaviour is made in terms of the development of microplastic zones which surround the fibres. (orig.) 9 refs.

  18. Simulation of Thermal-Mechanical Strength for Marine Engine Piston Using FEA

    Directory of Open Access Journals (Sweden)

    Jiang Guo He

    2014-03-01

    Full Text Available Simulation of Thermal-Mechanical Strength for Marine Engine Piston Using FEA Abstract: This paper involves simulation of a 2-stroke 6S35ME marine diesel engine piston to determine its temperature field, thermal, mechanical and coupled thermal-mechanical stress. The distribution and magnitudes of the afore-mentioned strength parameters are useful in design, failure analysis and optimization of the engine piston. The piston model was developed in solid-works and imported into ANSYS for preprocessing, loading and post processing. Material model chosen was 10-node tetrahedral thermal solid 87. The simulation parameters used in this paper were piston material, combustion pressure, inertial effects and temperature. The highest calculated stress was the thermal-mechanical coupled stress and was below the yield stress of the piston material (580Mpa at elevated temperatures hence the piston would withstand the induced stresses during work cycles.

  19. Mechanical and Thermal Properties of Polymethyl Methacrylate-BN Nanotube Composites

    Directory of Open Access Journals (Sweden)

    C. Y. Zhi

    2008-01-01

    Full Text Available Polymethyl methacrylate (PMMA-BN nanotube (BNNT composites were fabricated and their mechanical and thermal properties were analyzed. Using a 1 wt.% BNNTs fraction in a polymer, the elastic modulus of PMMA was increased up to 19%. In addition, thermal stability and glass transition temperature of PMMA were also positively affected. The thermal conductivity of PMMA with BNNT additions increased three times. The resultant BNNT-PMMA composites possess the high electrical breakover voltages. Thus our studies clearly indicate that BNNTs are promising nanofillers for improvement of mechanical and thermal conductivity of dielectric polymers under preservation of their electrical insulation.

  20. Thermal-mechanical and thermal-hydraulic integrated study of the Helium-Cooled Lithium Lead Test Blanket Module

    Energy Technology Data Exchange (ETDEWEB)

    Chiovaro, P., E-mail: pg.chiovaro@din.unipa.it [Dipartimento di Ingegneria Nucleare, Universita di Palermo, Palermo (Italy); Di Maio, P.A.; Giammusso, R.; Lupo, Q.; Vella, G. [Dipartimento di Ingegneria Nucleare, Universita di Palermo, Palermo (Italy)

    2010-12-15

    The Helium-Cooled Lithium Lead Test Blanket Module (HCLL-TBM) is one of the two TBM to be installed in an ITER equatorial port since day 1 of operation, with the specific aim to investigate the main concept functionalities and issues such as high efficiency helium cooling, resistance to thermo-mechanical stresses, manufacturing techniques, as well as tritium transport, magneto-hydrodynamics effects and corrosion. In particular, in order to show a DEMO-relevant thermo-mechanical and thermal-hydraulic behavior, the HCLL-TBM has to meet several requirements especially as far as its coolant thermofluid-dynamic conditions and its thermal-mechanical field are concerned. The present paper is focused on the assessment of the HCLL-TBM thermal-mechanical performances under both nominal and accidental load conditions, by adopting a computational approach based on the Finite Element Method. A realistic 3D finite element model of the whole HCLL-TBM, in the horizontal first wall design has been set up, consisting of about 597,000 elements and 767,000 nodes. In particular, since the thermal fields of both the module and the coolant are strictly coupled, the helium flow domain has been modeled too and a thermal contact model has been set up to properly simulate the convective heat transfer between the structure wall and the coolant. Pure conductive heat transfer has been assumed within the Pb-Li eutectic alloy of the breeder units. The volumetric density of the nuclear deposited power, recently calculated at Department of Nuclear Engineering of the University of Palermo by the MCNP 4C code, has been applied as distributed thermal load in order to assess the potential influence on the module thermo-mechanical performances of the markedly non-uniform poloidal and toroidal distributions that have been predicted within the Segment Box. Different loading scenarios have been considered as to the heat flux onto the module First Wall. Steady state and transient thermal-mechanical analyses

  1. Thermal and Mechanical Design Aspects of the LIFE Engine

    Energy Technology Data Exchange (ETDEWEB)

    Abbott, R P; Gerhard, M A; Latkowski, J F; Kramer, K J; Morris, K R; Peterson, P F; Seifried, J E

    2008-10-25

    The Laser Inertial confinement fusion - Fission Energy (LIFE) engine encompasses the components of a LIFE power plant responsible for converting the thermal energy of fusion and fission reactions into electricity. The design and integration of these components must satisfy a challenging set of requirements driven by nuclear, thermal, geometric, structural, and materials considerations. This paper details a self-consistent configuration for the LIFE engine along with the methods and technologies selected to meet these stringent requirements. Included is discussion of plant layout, coolant flow dynamics, fuel temperatures, expected structural stresses, power cycle efficiencies, and first wall survival threats. Further research and to understand and resolve outstanding issues is also outlined.

  2. Effect of thermal-treatment sequence on sound absorbing and mechanical properties of porous sound-absorbing/thermal-insulating composites

    OpenAIRE

    Huang Chen-Hung; Tsay Cherng-Shiuan; Lou Ching-Wen; Chuang Yu-Chun; Shih Ying-Huei; Lin Jia-Horng

    2016-01-01

    Due to recent rapid commercial and industrial development, mechanical equipment is supplemented massively in the factory and thus mechanical operation causes noise which distresses living at home. In livelihood, neighborhood, transportation equipment, jobsite construction noises impact on quality of life not only factory noise. This study aims to preparation technique and property evaluation of porous sound-absorbing/thermal-insulating composites. Hollow three-dimensional crimp PET fibers ble...

  3. Expanding Newton Mechanics with Neutrosophy and Quadstage Method ──New Newton Mechanics Taking Law of Conservation of Energy as Unique Source Law

    Directory of Open Access Journals (Sweden)

    Fu Yuhua

    2014-06-01

    Full Text Available Neutrosophy is a new branch of philosophy, and "Quad-stage" (Four stages is the expansion of Hegel’s triad thesis, antithesis, synthesis of development. Applying Neutrosophy and "Quad-stage" method, the purposes of this paper are expanding Newton Mechanics and making it become New Newton Mechanics (NNW taking law of conservation of energy as unique source law. In this paper the examples show that in some cases other laws may be contradicted with the law of conservation of energy. The original Newton's three laws and the law of gravity, in principle can be derived by the law of conservation of energy. Through the example of free falling body, this paper derives the original Newton's second law by using the law of conservation of energy, and proves that there is not the contradiction between the original law of gravity and the law of conservation of energy; and through the example of a small ball rolls along the inclined plane (belonging to the problem cannot be solved by general relativity that a body is forced to move in flat space, derives improved Newton's second law and improved law of gravity by using law of conservation of energy. Whether or not other conservation laws (such as the law of conservation of momentum and the law of conservation of angular momentum can be utilized, should be tested by law of conservation of energy. When the original Newton's second law is not correct, then the laws of conservation of momentum and angular momentum are no longer correct; therefore the general forms of improved law of conservation of momentum and improved law of conservation of angular momentum are presented. In the cases that law of conservation of energy cannot be used effectively, New Newton Mechanics will not exclude that according to other theories or accurate experiments to derive the laws or formulas to solve some specific problems. For example, with the help of the result of general relativity, the improved Newton's formula of universal

  4. Thermal cycling, oxidation behaviour and mechanical properties of graded and duplex PSZ TBC coatings

    Energy Technology Data Exchange (ETDEWEB)

    Musil, J. [SKODA, Plzen (Czech Republic); Alaya, M.; Oberacker, R. [Univ. of Karlsruhe (Germany)

    1995-07-01

    Plasma sprayed duplex and graded ZrO{sub 2} thermal barrier coatings (TBCs) on an Inconel 617 substrate with a NiCrAlY bond coat were investigated and compared with regard to their thermal cycling, oxidation behaviour and mechanical properties. On the basis of FE - calculations the stress distribution within thermally cycled coating systems was analyzed. The calculations show that the graded coating structure relaxes considerably the stresses resulting from the internal constraint due to thermal expansion difference between both metallic and ceramic materials and hence must lead to a better thermal cycling behaviour of the graded TBC systems. Mechanical tests confirm it. However, taking into account their poor oxidation behaviour, the lifetime of duplex TBC systems which are under steady-state thermal load conditions is much higher than that of graded ones.

  5. Parametric fuselage design: Integration of mechanics and acoustic & thermal insulation

    NARCIS (Netherlands)

    Krakers, L.A.

    2009-01-01

    Designing a fuselage is a very complex process, which involves many different aspects like strength and stability, fatigue, damage tolerance, fire resistance, thermal and acoustic insulation but also inspection, maintenance, production and repair aspects. It is difficult to include all design aspect

  6. Parametric fuselage design: Integration of mechanics and acoustic & thermal insulation

    NARCIS (Netherlands)

    Krakers, L.A.

    2009-01-01

    Designing a fuselage is a very complex process, which involves many different aspects like strength and stability, fatigue, damage tolerance, fire resistance, thermal and acoustic insulation but also inspection, maintenance, production and repair aspects. It is difficult to include all design aspect

  7. Enhancement in thermal and mechanical properties of bricks

    Directory of Open Access Journals (Sweden)

    Shibib Khalid S.

    2013-01-01

    Full Text Available A new type of porous brick is proposed. Sawdust is initially well mixed with wet clay in order to create voids inside the brick during the firing process. The voids will enhance the total performance of the brick due to the reduction of its density and thermal conductivity and a minor reduction of its compressive stress. All these properties have been measured experimentally and good performance has been obtained. Although a minor reduction in compressive stress has been observed with increased porosity, this property has still been larger than that of the common used hollow brick. Data obtained by this work lead to a new type of effective brick having a good performance with no possibility that mortar enters inside the holes which is the case with the common used hollow bricks. The mortar has a determent effect on thermal properties of the wall since it has some higher thermal conductivity and density than that of brick which increases the wall overall density and thermal conductivity of the wall.

  8. IN-SITU THERMAL REMEDIATION: MECHANISMS, PRINCIPLES, AND CASE STUDIES

    Science.gov (United States)

    Since the early 1990's, thermal methods of enhanced oil recovery have been adapted for the remediation of soils and groundwater. Steam injection and electrical resistance heating have proven to be robust and aggressive techniques for the enhanced recovery of volatile and semivol...

  9. Thermal and mechanical joints to cryo-cooled silicon monochromatorcrystals

    Energy Technology Data Exchange (ETDEWEB)

    MacDowell, A.; Fakra, S.; Morrison, G.

    2006-07-14

    We describe the performance of various materials used as thethermal interface between silicon to silicon and silicon to copper jointswhen operated at ~;120K and loaded with ~;20 watts of thermal power. Wefind that only the indium based silicon-to-silicon joint isreliable.

  10. Investigation of casing connection failure mechanisms in thermal wells

    Energy Technology Data Exchange (ETDEWEB)

    Xie, J. [C-FER Technologies, Edmonton, AB (Canada)

    2009-07-01

    Thermal well technologies use casing strings that consist of casing joints linked by threaded connections that are cemented over the wellbore's length in order to provide structural support and hydraulic isolation to the wellbore. Studies have demonstrated that over 80 per cent of uphole casing failures occur at the casing joint connections, and are caused by thread rupture or structural damage. This study discussed thermal well failures related to casing connection damage. Finite element analyses (FEA) were then conducted to consider various critical load conditions with a generic premium casing connection. The study considered structural integrity losses, fatigue, and leakage during connection installation. Results of the study were then used to optimize casing connection designs. The study showed that thermal cycle and curvature loading can have an impact on the structural and sealing performance of premium connections. Connection structural performance should be evaluated in order to determine appropriate designs for thermal well applications. It was concluded that the connection shoulder region is a critical area for material fatigue failure. 12 refs., 9 figs.

  11. Aging Effects and Estimating Degradation Mechanisms of Thermally Upgraded Paper in Mineral Oil

    Science.gov (United States)

    Miyagi, Katsunori; Oe, Etsuo; Yamagata, Naoki

    The life of a transformer is limited to the deterioration of its solid insulation. Winding conductors and other solid insulation materials in oil-immersed transformers have been insulated using cellulose products. For many years, manufacturers have met the needs of special applications by designing transformers using thermally upgraded materials to achieve lighter weight, higher power density and increased life. Recently, the effect of thermally upgraded insulation on diagnostic techniques such as gas-in oil analysis, and their indication of insulation degradation have been reviewed. This paper describes evaluations of the thermal degradation characteristics and decomposition reactions in mineral transformer oil of amine-impregnated thermally upgraded paper insulation. The thermal resistance of the thermally upgraded paper is evaluated by comparison with Kraft paper insulation. Further, aging degradation mechanisms of decompositional degradation of the thermally upgraded paper due to aging in mineral transformer oil are proposed.

  12. Thermal Mechanical Stability of Single-Crystal-Oxide Refractive Concentrators Evaluated for High-Temperature Solar-Thermal Propulsion

    Science.gov (United States)

    Jacobson, Nathan S.; Jacobson, Nathan S.; Miller, Robert A.

    1999-01-01

    Recently, refractive secondary solar concentrator systems were developed for solar thermal power and propulsion (ref. 1). Single-crystal oxides-such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium aluminum garnet (Y3Al5O12, or YAG), magnesium oxide (MgO), and sapphire (Al2O3)-are candidate refractive secondary concentrator materials. However, the refractive concentrator system will experience high-temperature thermal cycling in the solar thermal engine during the sun/shade transition of a space mission. The thermal mechanical reliability of these components in severe thermal environments is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions. In this research at the NASA Lewis Research Center, a controlled heat flux test approach was developed for investigating the thermal mechanical stability of the candidate oxide. This approach used a 3.0-kW continuous-wave (wavelength, 10.6 mm) carbon dioxide (CO2) laser (ref. 2). The CO2 laser is especially well-suited for single-crystal thermal shock tests because it can directly deliver well-characterized heat energy to the oxide surfaces. Since the oxides are opaque at the 10.6-mm wavelength of the laser beam, the light energy is absorbed at the surfaces rather than transmitting into the crystals, and thus generates the required temperature gradients within the specimens. The following figure is a schematic diagram of the test rig.

  13. Thermo-mechanical effects of thermal cycled copper through-silicon vias

    Science.gov (United States)

    Marro, James

    The semiconductor industry is currently facing transistor scaling issues due to fabrication thresholds and quantum effects. In this "More-Than-Moore" era, the industry is developing new ways to increase device performance, such as stacking chips for three-dimensional integrated circuits (3D-IC). The 3D-IC's superior performance over their 2D counterparts can be attributed to the use of vertical interconnects, or through silicon vias (TSV). These interconnects are much shorter, reducing signal delay. However TSVs are susceptible to various thermo-mechanical reliability concerns. Heating during fabrication and use, in conjunction with coefficient of thermal expansion mismatch between the copper TSVs and silicon substrate, create harmful stresses in the system. The purpose of this work is to evaluate the signal integrity of Cu-TSVs and determine the major contributing factors of the signal degradation upon in-use conditions. Two series of samples containing blind Cu-TSVs embedded in a Si substrate were studied, each having different types and amounts of voids from manufacturing. The samples were thermally cycled up to 2000 times using three maximum temperatures to simulate three unique in-use conditions. S11 parameter measurements were then conducted to determine the signal integrity of the TSVs. To investigate the internal response from cycling, a protocol was developed for cross-sectioning the copper TSVs. Voids were measured using scanning electron microscope and focused ion beam imaging of the cross-sections, while the microstructural evolution of the copper was monitored with electron backscattering diffraction. An increase in void area was found to occur after cycling. This is thought to be the major contributing factor in the signal degradation of the TSVs, since no microstructural changes were observed in the copper.

  14. Mechanical response of a capacitive microsensor under thermal load

    Science.gov (United States)

    Faris, Waleed; Nayfeh, Ali H.

    2007-08-01

    A considerable fraction of commercial sensors are electrostatically actuated. Many sensor diaphragms are operated in different thermal environments that affect their performance. Because the interplay between the thermal and electrostatic loadings is of interest to designers, in this work we investigate such an interplay. We start with the coupled heat conduction equation and the Saint-Venant plate model. We use nondimensional analysis to show that the dissipation and the elastic coupling vary on a slow scale and hence they can be neglected. Consequently, the heat equation is uncoupled from the plate equation. We consider the case in which the temperature at the boundary is kept at a constant value above the ambient temperature. Substituting the resulting temperature distribution into the plate equation yields an equation with an equivalent compressive load and an electrostatic load due to a DC voltage. Then, a reduced-order model is used to investigate the influence of the dual loading on the plate deflection and their interplay.

  15. Mechanical and Thermal Properties of Polysiloxanes and NBR Blend Elastomer

    Institute of Scientific and Technical Information of China (English)

    WANG Yanbing; HUANG Zhixiong; ZHANG Lianmeng; MEI Qilin

    2006-01-01

    A series of elastomers, based on NBR, polysiloxanes (PS) were prepared and characterized by tensile tests, thermogravimetry (TG) and differential scanning calorimetry ( DSC ). Two kinds of vulcanizing agent, DMDBH ( 2 , 5- dimethyl- 2 , 5- di ( t- batyl perory ) hexane ) and DCP ( dicumylperoxide ) were used to investigate the irfluence of different vulcanizing agents on properties of PS/NBR. The addition of PS to NBR was found to improve the thermal stability and decrease the tensile strength of NBR. The tensile strength decreased considerably while the elongation at break increased obviously with the increase of PS content. The series using DMDBH as vulcanizing agent showed a higher tensile strength and elongation at break than the series using DCP as vulcanizing agent. Simultaneity the thermal stability increased with the increase of PS content.

  16. An Iris Mechanism Driven Temperature Control of Solar Thermal Reactors

    OpenAIRE

    Van den Langenbergh, Lode; Ophoff, Cédric; Ozalp, Nesrin

    2015-01-01

    In spite of their attraction for clean production of fuels and commodities; solar thermal reactors are challenged by the transient nature of solar energy. Control of reactor temperature during transient periods is the key factor to maintain solar reactor performance. Currently, there are few techniques that are being used to accommodate the fluctuations of incoming solar radiation. One of the commonly practiced methods is to adjust the mass flow rate of the feedstock which is very simple to i...

  17. Enhancement in thermal and mechanical properties of bricks

    OpenAIRE

    Shibib Khalid S.; Qatta Haqi I.; Hamza Mohammed S.

    2013-01-01

    A new type of porous brick is proposed. Sawdust is initially well mixed with wet clay in order to create voids inside the brick during the firing process. The voids will enhance the total performance of the brick due to the reduction of its density and thermal conductivity and a minor reduction of its compressive stress. All these properties have been measured experimentally and good performance has been obtained. Although a minor reduction in compressive s...

  18. Multifunctional Thermal Structures Using Cellular Contact-Aided Complaint Mechanisms

    Science.gov (United States)

    2016-10-31

    Mars Exploration Rover mission [Sunada et al., 2002, Novak et al. 2003]. Differential thermal expansion (DTE) uses two materials with different...Transfer, vol. 46, no. 24, p. 4573–4586, 2003. Novak , K. S., Phillips, C. J., Birur, G. C., Sunada E. T., and Pauken, M. T., “Development of a...unilateral contact,” Structural and Multidisciplinary Optimization, Vol. 41, No. 1, Feb 2010, pp. 57 - 64. Sunada, E., Lankford, K., Pauken, M., Novak , K. S

  19. Multifunctional Thermal Structures Using Cellular Contract-Aided Complaint Mechanisms

    Science.gov (United States)

    2017-01-26

    Mars Exploration Rover mission [Sunada et al., 2002, Novak et al. 2003]. Differential thermal expansion (DTE) uses two materials with different...Transfer, vol. 46, no. 24, p. 4573–4586, 2003. Novak , K. S., Phillips, C. J., Birur, G. C., Sunada E. T., and Pauken, M. T., “Development of a...unilateral contact,” Structural and Multidisciplinary Optimization, Vol. 41, No. 1, Feb 2010, pp. 57 - 64. Sunada, E., Lankford, K., Pauken, M., Novak , K. S

  20. Acceleration of Thermal Protons By Generic Phenomenological Mechanisms

    CERN Document Server

    Petrosian, Vahé

    2016-01-01

    We investigate heating and acceleration of protons from a thermal gas with a generic diffusion and acceleration model, and subject to Coulomb scattering and energy loss, as was carried out in Petrosian & East (2008) for electrons. As protons gain energy their loss to electrons becomes important. Thus, we need to solve the coupled proton-electron kinetic equation. We numerically solve the coupled Fokker-Plank equations and computes the time evolution of the spectra of both particles. We show that this can lead to a quasi-thermal component plus a high energy nonthermal tail. We determine the evolution of nonthermal tail and the quasi-thermal component. The results may be used to explore the possibility of inverse bremsstrahlung radiation as a source of hard X-ray emissions from hot sources such as solar flares, accretion disk coronas and the intracluster medium of galaxy clusters. We find that emergence of nonthermal protons is accompanied by excessive heating of the entire plasma, unless the turbulence nee...

  1. Dissociative mechanism of F-actin thermal denaturation.

    Science.gov (United States)

    Mikhailova, V V; Kurganov, B I; Pivovarova, A V; Levitsky, D I

    2006-11-01

    We have applied differential scanning calorimetry to investigate thermal unfolding of F-actin. It has been shown that the thermal stability of F-actin strongly depends on ADP concentration. The transition temperature, T(m), increases with increasing ADP concentration up to 1 mM. The T(m) value also depends on the concentration of F-actin: it increases by almost 3 degrees C as the F-actin concentration is increased from 0.5 to 2.0 mg/ml. Similar dependence of the T(m) value on protein concentration was demonstrated for F-actin stabilized by phalloidin, whereas it was much less pronounced in the presence of AlF4(-). However, T(m) was independent of protein concentration in the case of monomeric G-actin. The results suggest that at least two reversible stages precede irreversible thermal denaturation of F-actin; one of them is dissociation of ADP from actin subunits, and another is dissociation of subunits from the ends of actin filaments. The model explains why unfolding of F-actin depends on both ADP and protein concentration.

  2. Thermal capacitator design rationale. Part 1: Thermal and mechanical property data for selected materials potentially useful in thermal capacitor design and construction

    Science.gov (United States)

    Bailey, J. A.; Liao, C. K.

    1975-01-01

    The thermal properties of paraffin hydrocarbons and hydrocarbon mixtures which may be used as the phase change material (PCM) in thermal capacitors are discussed. The paraffin hydrocarbons selected for consideration are those in the range from C11H24 (n-Undecane) to C20H42 (n-Eicosane). A limited amount of data is included concerning other properties of paraffin hydrocarbons and the thermal and mechanical properties of several aluminum alloys which may find application as constructional materials. Data concerning the melting temperature, transition temperature, latent heat of fusion, heat of transition, specific heat, and thermal conductivity of pure and commercial grades of paraffin hydrocarbons are given. An index of companies capable of producing paraffin hydrocarbons and information concerning the availability of various grades (purity levels) is provided.

  3. Differential regulation of peripheral IL-1β-induced mechanical allodynia and thermal hyperalgesia in rats.

    Science.gov (United States)

    Kim, Min J; Lee, Sang Y; Yang, Kui Y; Nam, Soon H; Kim, Hyun J; Kim, Young J; Bae, Yong C; Ahn, Dong K

    2014-04-01

    This study examined the differential mechanisms of mechanical allodynia and thermal hyperalgesia after injection of interleukin (IL) 1β into the orofacial area of male Sprague-Dawley rats. The subcutaneous administration of IL-1β produced both mechanical allodynia and thermal hyperalgesia. Although a pretreatment with iodoresiniferatoxin (IRTX), a transient receptor potential vanilloid 1 (TRPV1) antagonist, did not affect IL-1β-induced mechanical allodynia, it significantly abolished IL-1β-induced thermal hyperalgesia. On the other hand, a pretreatment with D-AP5, an N-methyl-d-aspartate (NMDA) receptor antagonist, and NBQX, an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, blocked IL-1β-induced mechanical allodynia. Pretreatment with H89, a protein kinase A (PKA) inhibitor, blocked IL-1β-induced mechanical allodynia but not thermal hyperalgesia. In contrast, pretreatment with chelerythrine, a protein kinase C (PKC) inhibitor, inhibited IL-1β-induced thermal hyperalgesia. Subcutaneous injections of 2% lidocaine, a local anesthetic agent, blocked IL-1β-induced thermal hyperalgesia but not IL-1β-induced mechanical allodynia. In the resiniferatoxin (RTX)-pretreated rats, a subcutaneous injection of IL-1β did not produce thermal hyperalgesia due to the depletion of TRPV1 in the primary afferent fibers. Double immunofluorescence revealed the colocalization of PKA with neurofilament 200 (NF200) and of PKC with the calcitonin gene-related peptide (CGRP) in the trigeminal ganglion. Furthermore, NMDA receptor 1 (NR1) and TRPV1 predominantly colocalize with PKA and PKC, respectively, in the trigeminal ganglion. These results suggest that IL-1β-induced mechanical allodynia is mediated by sensitized peripheral NMDA/AMPA receptors through PKA-mediated signaling in the large-diameter primary afferent nerve fibers, whereas IL-1β-induced thermal hyperalgesia is mediated by sensitized peripheral TRPV1 receptors through PKC

  4. Restabilizing Mechanisms after the Onset of Thermal Instability in Bipolar Transistors

    Institute of Scientific and Technical Information of China (English)

    CHEN Liang; ZHANG Wan-Rong; XIE Hong-Yun; JIN Dong-Yue; DING Chun-Bao; FU Qiang; WANG Ren-Qing; XIAO Ying; ZHAO Xin

    2011-01-01

    The restabilizing mechanisms after the onset of thermal instability in bipolar transistors are studied by theoretical analyses,computer simulations and experimental measurements.Restability conditions are described by novel analytical formulae.Furthermore,the expression of collect current in the second fly-back point is given for the first time.The effects of emitter ballast resistance,collector-emitter voltage and thermal resistance on restabilization mechanisms are expressed and investigated.

  5. Curing mechanism of furan resin modified with different agents and their thermal strength

    Directory of Open Access Journals (Sweden)

    Huang Renhe

    2011-05-01

    Full Text Available The curing mechanism of furfuryl alcohol and urea-formaldehyde furan resins was investigated using infrared spectroscopy (IR technique. The curing productions of urea-formaldehyde furan resins modified with different agents (i.e. sorbitol, polyester polyol, phenol and acetone and the productions of incomplete curing were characterized by differential thermal analysis (DTA and thermal gravity analysis (TG. The results indicate that except for polyester polyol, the other modifiers have little effect on the thermal strength of urea-formaldehyde furan resin. Furthermore, the thermal strength can be improved at a temperature of higher than 550℃.

  6. Mechanical and thermal stresses analysis in diesel engine exhaust valve with and without thermal coating layer on valve face

    Directory of Open Access Journals (Sweden)

    Maher A.R. Sadiq Al-Baghdadi,Sahib Shihab Ahmed, Nabeel Abdulhadi Ghayadh

    2016-01-01

    Full Text Available This paper investigates mechanical and thermal stresses that arise in the exhaust valve due to its operating with and without thermal coating layer (ceramic on face exhaust valve. Three dimensional models of an exhaust valve four cylinders, four stroke, and direct injection diesel engine have been presented. The governing equations were discretized using a finite-volume method (FVM and solved using multi-physics COMSOL package Version 5. The engine’s exhaust valve crown is coated with various materials in different thermal conductivity such as (Gd2Zr2O7, over a 150μm thickness of bond coat. The maximum thickness of coating is about 300 μm. Results indicate that after creating a coating layer exhaust valve the temperature distribution, temperature gradients distribution, von-Mises stress distribution and displacement distribution are decreased.

  7. A rat model of full thickness thermal injury characterized by thermal hyperalgesia, mechanical allodynia, pronociceptive peptide release and tramadol analgesia.

    Science.gov (United States)

    Fowler, Marcie; Clifford, John L; Garza, Thomas H; Slater, Terry M; Arizpe, Helen M; Novak, Joseph; Petz, Lawrence N; Loyd, Dayna R

    2014-06-01

    Opioid-related side effects are problematic for burn patients. Dual mechanism therapeutics targeting opioid and non-opioid mechanisms may have reduced side effects with similar analgesic efficacy. Tramadol combines mu opioid receptor agonism with norepinephrine reuptake inhibition and has been effective in treating some types of pain. The effectiveness of tramadol in treating pain associated with burns is unclear. We hypothesized that tramadol is effective in reducing thermal injury-evoked pain behaviors in a rat model. Rats were anesthetized and a 100°C metal probe was placed on the hindpaw for 30 s to induce a full thickness thermal injury. A subset of rats was perfusion fixed and hindpaw tissue and spinal cord collected for anatomical analysis. Rats received morphine (5 mg/kg; i.p.), tramadol (10-30 mg/kg; i.p.) or vehicle and latency to paw withdrawal from a noxious thermal or non-noxious mechanical stimulus was recorded every 10 min over 70 min and again at 2 h. We report that pain behaviors developed within 48 h and peaked at 1 week; paralleled by enhanced expression of pronociceptive neuropeptides in the spinal cord. Morphine and tramadol significantly attenuated hyperalgesia and allodynia, while not significantly altering motor coordination/sedation. These data indicate dual mechanism therapeutics may be effective for treating pain associated with burns.

  8. Mechanical and Thermal Tests of the Containers of Liquid Mirrors

    CERN Document Server

    Borra, E F; Tremblay, G; Daigle, A; Huot, Y

    2003-01-01

    We give a generic description of a liquid mirror system and summarize some practical information useful to making them. We compare laboratory measurements of deformations, due to the weight of mercury on the container of a 3.7-m mirror and to temperature changes on a 1-m container, to finite element computer simulations. We find that the measurements agree reasonably well with the numerical simulations. The measurements on the 1-m container show no evidence of fatigue after a few thermal cycles. These results validate the computer models of containers described in a companion article.

  9. Polymer nanocomposites with enhanced thermal and mechanical properties

    Science.gov (United States)

    Si, Mayu

    Flame-retardant Elvacite acrylic resin/Cloisite 6A nanocomposites were prepared via direct melt intercalation. Transmission electron microscopy (TEM) micrographs showed that the high degree of exfoliation occurred, which resulted in a large improvement in thermal stability and UV absorption properties without sacrificing optical clarity. Cone calorimetry tests clearly showed that the heat release rate was far lower and more gradual in the nanocomposites than in pure resins. Additionally, Fourier transform infrared (FTIR) spectroscopy results indicated that the introduction of clay did not change the chemical structure of acrylic resins.

  10. Mechanical, thermal, and barrier properties of methylcellulose/cellulose nanocrystals nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Silverio, Hudson Alves; Flauzino Neto, Wilson Pires; Silva, Ingrid Souza Vieira da; Rosa, Joyce Rover; Pasquini, Daniel, E-mail: pasquini@iqufu.ufu.br, E-mail: danielpasquini2005@yahoo.com.br [Universidade de Uberlandia (USU), MG (Brazil). Instituto de Quimica; Assuncao, Rosana Maria Nascimento de [Universidade de Uberlandia (USU), Ituiutaba, MG (brazil). Fac. de Ciencias Integradas do Pontal; Barud, Hernane da Silva; Ribeiro, Sidney Jose Lima [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Araraquara, SP (Brazil). Instituto de Quimica

    2014-11-15

    In this work, the effects of incorporating cellulose nanocrystals from soy hulls (WSH{sub 30}) on the mechanical, thermal, and barrier properties of methylcellulose (MC) nanocomposites were evaluated. MC/WSH{sub 30} nanocomposite films with different filler levels (2, 4, 6, 8, and 10%) were prepared by casting. Compared to neat MC film, improvements in the mechanical and barrier properties were observed, while thermal stability was retained. The improved mechanical properties of nanocomposites prepared may be attributed to mechanical percolation of WSH{sub 30}, formation of a continuous network of WSH{sub 30} linked by hydrogen interactions and a close association between filler and matrix. (author)

  11. Thermal and Mechanical Characteristics of Polymer Composites Based on Epoxy Resin, Aluminium Nanopowders and Boric Acid

    Science.gov (United States)

    Nazarenko, O. B.; Melnikova, T. V.; Visakh, P. M.

    2016-01-01

    The epoxy polymers are characterized by low thermal stability and high flammability. Nanoparticles are considered to be effective fillers of polymer composites for improving their thermal and functional properties. In this work, the epoxy composites were prepared using epoxy resin ED-20, polyethylene polyamine as a hardener, aluminum nanopowder and boric acid fine powder as flame-retardant filler. The thermal characteristics of the obtained samples were studied using thermogravimetric analysis and differential scanning calorimetry. The mechanical characteristics of epoxy composites were also studied. It was found that an addition of all fillers enhances the thermal stability and mechanical characteristics of the epoxy composites. The best thermal stability showed the epoxy composite filled with boric acid. The highest flexural properties showed the epoxy composite based on the combination of boric acid and aluminum nanopowder.

  12. Mechanical and thermal properties of tungsten carbide – graphite nanoparticles nanocomposites

    Directory of Open Access Journals (Sweden)

    Kornaus Kamil

    2016-06-01

    Full Text Available Previous studies concerning pure tungsten carbide polycrystalline materials revealed that nanolayers of graphite located between WC grains improve its thermal properties. What is more, pressure-induced orientation of graphene nano platelets (GNP in hot pressed silicon nitride-graphene composites results in anisotropy of thermal conductivity. Aim of this study was to investigate if addition of GNP to WC will improve its thermal properties. For this purpose, tungsten carbide with 0.5–6 wt.% of GNP(12-additive underwent hot pressing. The microstructure observations performed by SEM microscopy. The anisotropy was determined via ultrasonic measurements. The following mechanical properties were evaluated: Vickers hardness, bending strength, fracture toughness KIc. The influence of GNP(12 addition on oxidation resistance and thermal conductivity was examined. It was possible to manufacture hot-pressed WC-graphene composites with oriented GNP(12 particles, however, the addition of graphene decreased both thermal and mechanical properties of the material.

  13. Coupled mechanical-electrical-thermal modeling for short-circuit prediction in a lithium-ion cell under mechanical abuse

    Science.gov (United States)

    Zhang, Chao; Santhanagopalan, Shriram; Sprague, Michael A.; Pesaran, Ahmad A.

    2015-09-01

    In order to better understand the behavior of lithium-ion batteries under mechanical abuse, a coupled modeling methodology encompassing the mechanical, electrical and thermal response is presented for predicting short-circuit under external crush. The combined mechanical-electrical-thermal response is simulated in a commercial finite element software LS-DYNA® using a representative-sandwich finite-element model, where electrical-thermal modeling is conducted after an instantaneous mechanical crush. The model includes an explicit representation of each individual component such as the active material, current collector, separator, etc., and predicts their mechanical deformation under quasi-static indentation. Model predictions show good agreement with experiments: the fracture of the battery structure under an indentation test is accurately predicted. The electrical-thermal simulation predicts the current density and temperature distribution in a reasonable manner. Whereas previously reported models consider the mechanical response exclusively, we use the electrical contact between active materials following the failure of the separator as a criterion for short-circuit. These results are used to build a lumped representative sandwich model that is computationally efficient and captures behavior at the cell level without resolving the individual layers.

  14. Thermal stresses in hexagonal materials - heat treatment influence on their mechanical behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Gloaguen, D.; Freour, S.; Guillen, R.; Royer, J. [Nantes Univ., GeM, Institut de Recherche en Genie Civil et Mecanique, Ecole Centrale de Nantes, UMR CNRS 6183, 44 (France); Francois, M. [Universite de Technologie de Troyes, Lab. des Systemes Mecaniques et d' Ingenierie Simultanee (LASMIS), 10 - Troyes (France)

    2004-12-01

    Internal stresses due to anisotropic thermal and plastic properties were investigated in rolled zirconium and titanium. The thermal stresses induced by a cooling process were predicted using a self-consistent model and compared with experimental results obtained by X-ray diffraction. The study of the elastoplastic response during uniaxial loading was performed along the rolling and the transverse direction of the sheet, considering the influence of the texture and the thermal stresses on the mechanical behaviour. An approach in order to determine the thermal behaviour of phases embedded in two-phase materials is also presented. For zirconium, the residual stresses due to thermal anisotropy are rather important (equivalent to 35% of the yield stress) and consequently they play an important role on the elastoplastic transition contrary to titanium. The study of two-phase material shows the influence and the interaction of the second phase on the thermal behaviour in the studied phase.

  15. Molecular mechanisms underlying thermal adaptation of xeric animals

    Indian Academy of Sciences (India)

    M B Evgen'Ev; D G Garbuz; V Y Shilova; O G Zatsepina

    2007-04-01

    For many years, we and our collaborators have investigated the adaptive role of heat shock proteins in different animals, including the representatives of homothermic and poikilothermic species that inhabit regions with contrasting thermal conditions. Adaptive evolution of the response to hyperthermia has led to different results depending upon the species. The thermal threshold of induction of heat shock proteins in desert thermophylic species is, as a rule, higher than in the species from less extreme climates. In addition, thermoresistant poikilothermic species often exhibit a certain level of heat shock proteins in cells even at a physiologically normal temperature. Furthermore, there is often a positive correlation between the characteristic temperature of the ecological niche of a given species and the amount of Hsp70-like proteins in the cells at normal temperature. Although in most cases adaptation to hyperthermia occurs without changes in the number of heat shock genes, these genes can be amplified in some xeric species. It was shown that mobile genetic elements may play an important role in the evolution and fine-tuning of the heat shock response system, and can be used for direct introduction of mutations in the promoter regions of these genes.

  16. Thermal-hydraulics/thermal-mechanics temporal coupling for unprotected loss of flow accidents simulations on a SFR

    Directory of Open Access Journals (Sweden)

    Patricot Cyril

    2016-01-01

    Full Text Available In the frame of ASTRID designing, unprotected loss of flow (ULOF accidents are considered. As the reactor is not scrammed, power evolution is driven by neutronic feedbacks, among which Doppler effect, linked to fuel temperature, is prominent. Fuel temperature is calculated using thermal properties of fuel pins (we will focus on heat transfer coefficient between fuel pellet and cladding, Hgap, and on fuel thermal conductivity, λfuel which vary with irradiation conditions (neutronic flux, mass flow and history for instance and during transient (mainly because of dilatation of materials with temperature. In this paper, we propose an analysis of the impact of spatial variation and temporal evolution of thermal properties of fuel pins on a CFV-like core [M.S. Chenaud et al., Status of the ASTRID core at the end of the pre-conceptual design phase 1, in Proceedings of ICAPP 2013, Jeju Island, Korea (2013] behavior during an ULOF accident. These effects are usually neglected under some a priori conservative assumptions. The vocation of our work is not to provide a best-estimate calculation of ULOF transient, but to discuss some of its physical aspects. To achieve this goal, we used TETAR, a thermal-hydraulics system code developed by our team to calculate ULOF transients, GERMINAL V1.5, a CEA code dedicated to SFR pin thermal-mechanics calculations and APOLLO3®, a neutronic code in development at CEA.

  17. Thermal-Mechanical Stability of Single Crystal Oxide Refractive Concentrators for High-Temperature Solar Thermal Propulsion

    Science.gov (United States)

    Zhu, Dongming; Jacobson, Nathan S.; Miller, Robert A.

    1999-01-01

    Single crystal oxides such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium aluminum garnet (Y3Al5O12, or YAG), magnesium oxide (MgO) and sapphire (Al2O3) are candidate refractive secondary concentrator materials for high temperature solar propulsion applications. However, thermo-mechanical reliability of these components in severe thermal environments during the space mission sun/shade transition is of great concern. Simulated mission tests are important for evaluating these candidate oxide materials under a variety of transient and steady-state heat flux conditions, and thus provide vital information for the component design. In this paper, a controlled heat flux thermal shock test approach is established for the single crystal oxide materials using a 3.0 kW continuous wave CO2 laser, with a wavelength 10.6 micron. Thermal fracture behavior and failure mechanisms of these oxide materials are investigated and critical temperature gradients are determined under various temperature and heating conditions. The test results show that single crystal sapphire is able to sustain the highest temperature gradient and heating-cooling rate, and thus exhibit the best thermal shock resistance, as compared to the yttria-stabilized zirconia, yttrium aluminum garnet and magnesium oxide.

  18. Thermal and nonThermal Mechanisms of Biological Interaction of Microwaves

    CERN Document Server

    Williams, J M

    2001-01-01

    Research in the past on the biological effects of microwaves often has been based on faulty assumptions. The major flaw has been the premise that microwaves only produce thermal effects in tissue. This premise easily may be proven physically incorrect. Furthermore, assuming only thermal effects leads one to an optimist's error of quantification in which calories are counted instead of joules. Past investigations have been misled both by these assumptions and by stereotyped experiments using only narrow band radiation sources. Recent studies show that wide band microwaves bring out biological effects which are unrelated to those caused by heat flow. A review by Kenneth Foster provides a basis for criticism and improved understanding. PACS: 87.10 87.22 87.50 87.54

  19. Interior and exterior ballistics coupled optimization with constraints of attitude control and mechanical-thermal conditions

    Science.gov (United States)

    Liang, Xin-xin; Zhang, Nai-min; Zhang, Yan

    2016-07-01

    For solid launch vehicle performance promotion, a modeling method of interior and exterior ballistics associated optimization with constraints of attitude control and mechanical-thermal condition is proposed. Firstly, the interior and external ballistic models of the solid launch vehicle are established, and the attitude control model of the high wind area and the stage of the separation is presented, and the load calculation model of the drag reduction device is presented, and thermal condition calculation model of flight is presented. Secondly, the optimization model is established to optimize the range, which has internal and external ballistic design parameters as variables selected by sensitivity analysis, and has attitude control and mechanical-thermal conditions as constraints. Finally, the method is applied to the optimal design of a three stage solid launch vehicle simulation with differential evolution algorithm. Simulation results are shown that range capability is improved by 10.8%, and both attitude control and mechanical-thermal conditions are satisfied.

  20. Experimental research on buckling of thin films in nano-scale under mechanical and thermal loading

    Science.gov (United States)

    Wang, S. B.; Jia, H. K.; Ren, X. C.; Li, L. A.

    2008-11-01

    In this paper, the mechanical and thermal properties of compressed thin film titanium films with 150nm thickness deposited on an organic glass substrate under mechanical and thermal loads were measured and characterized. In order to simulate the thin films in IT which subjected compound loads and to produce the buckle modes, the external uniaxial compression and thermal loading are subjected to the specimen by the symmetric loading device and the electrical resistance film in this experiment. The temperature of the thin film deposited on substrate was measured using thermoelectric couple. The range of temperature accords with the temperature range of the MEMS. It is found that the size and number of the delamination and buckling of the film are depended upon the pre-fixed mechanical loading. The transient conduction and thermal stability of the film and substrate was studied with finite element method.

  1. Effects of Composition and Thermal Cycle on Transformation Behaviors, Thermal Stability and Mechanical Properties of CuAlAg Alloy

    Institute of Scientific and Technical Information of China (English)

    Yunqing MA; Chengbao JIANG; Lifen DENG; Huibin XU

    2003-01-01

    The phase transformation behavior, mechanical properties, and the thermal stability of CuAlAg alloy were studied andminor rare earth (0.1 wt pct La+Ce) was added to improve the mechanical property of the studied alloy. It was foundthat Ag addition in the CuAl binary alloy can improve the stability of martensitic transformation and high Al contentleads to the disappearing of martensitic transformation. The tensile strength and strain of the Cu-10.6Al-5.8Ag (wtpct) alloy were measured to be 383.5 MPa and 0.86%, respectively. With rare earth addition, the tensile strainincreased from 0.86% to 1.47%. The CuAlAg alloy did not exhibit martensitic transformation on the second heatingprocess. Its poor thermal stability still needs to be improved.

  2. Thermal-Mechanical and Thermal Behavior of High-Temperature Structural Materials.

    Science.gov (United States)

    1979-12-31

    sub- jected t3 sudden co-nvectie heating at time of maimum tonsile stress. for the spatial variations of the thermail conductivitv given in Fi2;. ! _L...increased to about 5 percent at 1000*C. No corrections for finite pulse width were necessary. The equipment was calibrated against Armco iron which...diffusivity of iron titanate. . lack of reproducibility of the "hysteresis" curve for the glass-r w Ni composites in repeated thermal cycling is

  3. Interpretation of Simultaneous Mechanical-Electrical-Thermal Failure in a Lithium-Ion Battery Module: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chao; Santhanagopalan, Shriram; Stock, Mark J.; Brunhart-Lupo, Nicholas; Gruchalla, Kenny

    2016-12-01

    Lithium-ion batteries are currently the state-of- the-art power sources for electric vehicles, and their safety behavior when subjected to abuse, such as a mechanical impact, is of critical concern. A coupled mechanical-electrical-thermal model for simulating the behavior of a lithium-ion battery under a mechanical crush has been developed. We present a series of production-quality visualizations to illustrate the complex mechanical and electrical interactions in this model.

  4. Application of Thermal Tool Holder in Mechanical Engineering

    Science.gov (United States)

    Kunstfeld, Jaroslav; Hajnyš, Jiří; Brychta, Josef; Hemžský, Pavel; Nicielnik, Henryk

    2016-10-01

    The paper is focused on testing the thermal tool holder during milling operation from the point of view shimmy and roughness machined surface of the equipped tool. Experimental work will include testing of surface roughness parameters of the machined surface structural steel 1.0553 (Fe510C1) in combination with the monolith three-lips cutter Kennametal F3AU177BDK38 from cemented carbide coated with TiAIN PVD coating. Experimental machining will distinguish the climb milling and conventional milling and will be done under predetermined conditions, always at 15 cycles and in relation to other types of fixture devices. All testing will be done at a sufficiently rigid machine CNC FGS 40/50. During machining will be measured and subsequently evaluated power machine during the milling process, shimmy and selected parameters of the roughness of the machined surface.

  5. Biomass pyrolysis: Thermal decomposition mechanisms of furfural and benzaldehyde

    Science.gov (United States)

    Vasiliou, AnGayle K.; Kim, Jong Hyun; Ormond, Thomas K.; Piech, Krzysztof M.; Urness, Kimberly N.; Scheer, Adam M.; Robichaud, David J.; Mukarakate, Calvin; Nimlos, Mark R.; Daily, John W.; Guan, Qi; Carstensen, Hans-Heinrich; Ellison, G. Barney

    2013-09-01

    The thermal decompositions of furfural and benzaldehyde have been studied in a heated microtubular flow reactor. The pyrolysis experiments were carried out by passing a dilute mixture of the aromatic aldehydes (roughly 0.1%-1%) entrained in a stream of buffer gas (either He or Ar) through a pulsed, heated SiC reactor that is 2-3 cm long and 1 mm in diameter. Typical pressures in the reactor are 75-150 Torr with the SiC tube wall temperature in the range of 1200-1800 K. Characteristic residence times in the reactor are 100-200 μsec after which the gas mixture emerges as a skimmed molecular beam at a pressure of approximately 10 μTorr. Products were detected using matrix infrared absorption spectroscopy, 118.2 nm (10.487 eV) photoionization mass spectroscopy and resonance enhanced multiphoton ionization. The initial steps in the thermal decomposition of furfural and benzaldehyde have been identified. Furfural undergoes unimolecular decomposition to furan + CO: C4H3O-CHO (+ M) → CO + C4H4O. Sequential decomposition of furan leads to the production of HC≡CH, CH2CO, CH3C≡CH, CO, HCCCH2, and H atoms. In contrast, benzaldehyde resists decomposition until higher temperatures when it fragments to phenyl radical plus H atoms and CO: C6H5CHO (+ M) → C6H5CO + H → C6H5 + CO + H. The H atoms trigger a chain reaction by attacking C6H5CHO: H + C6H5CHO → [C6H6CHO]* → C6H6 + CO + H. The net result is the decomposition of benzaldehyde to produce benzene and CO.

  6. Models for thermal and mechanical monitoring of power transformers

    Energy Technology Data Exchange (ETDEWEB)

    Vilaithong, Rummiya

    2011-07-01

    At present, for economic reasons, there is an increasing emphasis on keeping transformers in service for longer than in the past. A condition-based maintenance using an online monitoring and diagnostic system is one option to ensure reliability of the transformer operation. The key parameters for effectively monitoring equipment can be selected by failure statistics and estimated failure consequences. In this work, two key aspects of transformer condition monitoring are addressed in depth: thermal behaviour and behaviour of on-load tap changers. In the first part of the work, transformer thermal behaviour is studied, focussing on top-oil temperatures. Through online comparison of a measured value of the top-oil temperature and its calculated value, some rapidly developing failures in power transformers such as malfunction of the cooling unit may be detected. Predictions of top-oil temperature can be obtained by means of a mathematical model. Long-term investigations on some dynamic top-oil temperature models are presented for three different types of transformer units. The last-state top-oil temperature, load current, ambient temperature and the operating state of pumps and fans are applied as inputs of the top-oil temperature models. In the fundamental physical models presented, some constant parameters are required and can be estimated using a least-squares optimization technique. Multilayer Feed-forward and Recurrent neural network models are also proposed and investigated. The neural network models are trained with three different Backpropagation training algorithms: Levenberg-Marquardt, Scaled Conjugate Gradient and Automated Bayesian Regularization. The effect of varying operating conditions of the cooling units and the non-steady-state behaviour of loading conditions, as well as ambient temperature are noted. Results show sophisticated temperature prediction is possible using the neural network models that is generally more accurate than with the physical

  7. Biomass pyrolysis: thermal decomposition mechanisms of furfural and benzaldehyde.

    Science.gov (United States)

    Vasiliou, AnGayle K; Kim, Jong Hyun; Ormond, Thomas K; Piech, Krzysztof M; Urness, Kimberly N; Scheer, Adam M; Robichaud, David J; Mukarakate, Calvin; Nimlos, Mark R; Daily, John W; Guan, Qi; Carstensen, Hans-Heinrich; Ellison, G Barney

    2013-09-14

    The thermal decompositions of furfural and benzaldehyde have been studied in a heated microtubular flow reactor. The pyrolysis experiments were carried out by passing a dilute mixture of the aromatic aldehydes (roughly 0.1%-1%) entrained in a stream of buffer gas (either He or Ar) through a pulsed, heated SiC reactor that is 2-3 cm long and 1 mm in diameter. Typical pressures in the reactor are 75-150 Torr with the SiC tube wall temperature in the range of 1200-1800 K. Characteristic residence times in the reactor are 100-200 μsec after which the gas mixture emerges as a skimmed molecular beam at a pressure of approximately 10 μTorr. Products were detected using matrix infrared absorption spectroscopy, 118.2 nm (10.487 eV) photoionization mass spectroscopy and resonance enhanced multiphoton ionization. The initial steps in the thermal decomposition of furfural and benzaldehyde have been identified. Furfural undergoes unimolecular decomposition to furan + CO: C4H3O-CHO (+ M) → CO + C4H4O. Sequential decomposition of furan leads to the production of HC≡CH, CH2CO, CH3C≡CH, CO, HCCCH2, and H atoms. In contrast, benzaldehyde resists decomposition until higher temperatures when it fragments to phenyl radical plus H atoms and CO: C6H5CHO (+ M) → C6H5CO + H → C6H5 + CO + H. The H atoms trigger a chain reaction by attacking C6H5CHO: H + C6H5CHO → [C6H6CHO]* → C6H6 + CO + H. The net result is the decomposition of benzaldehyde to produce benzene and CO.

  8. Modeling thermal-mechanical behavior of networks with reconfigurable crosslinks

    Science.gov (United States)

    Yang, Jeh-Chang; Meng, Yuan; Anthamatten, Mitchell

    Actively moving polymers nearly always involve the storage or release of mechanical energy using external stimuli. Thermomechanical experiments were conducted on well-defined chemical networks bearing both permanent and light-reconfigurable covalent junctions. Experimental data include stress relaxation and mechanical creep during photoinduced network reconfiguration as well as equilibrium stress-strain behavior of reprogrammed networks. Physical models of elastic networks were applied to describe thermomechanical behavior during and after bond re-formation while under external stress. The role of dangling ends in influencing competitive network mechanics is evaluated to explain observed phenomena and discrepancies between theory and data. Understanding how process path is related to the equilibrium thermomechanics of such reprogrammed networks is important to engineering shape actuator driven by crystallization. Nsf ECCS-1530540.

  9. Mechanism of unique hardening of dental Ag-Pd-Au-Cu alloys in relation with constitutional phases

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yonghwan [Department of Materials Science, Graduate School of Engineering, Tohoku University, 6-6 Aoba, Aramaki Aza, Aoba-ku, Sendai 980-8579 (Japan); Niinomi, Mitsuo, E-mail: niinomi@imr.tohoku.ac.jp [Department of Biomaterials Science, Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Nakai, Masaaki; Akahori, Toshikazu [Department of Biomaterials Science, Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Kanno, Toru [Department of Materials Science, Graduate School of Engineering, Tohoku University, 6-6 Aoba, Aramaki Aza, Aoba-ku, Sendai 980-8579 (Japan); Fukui, Hisao [Department of Dental Materials Science, School of Dentistry, Aichi-Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya 464-8650 (Japan)

    2012-04-05

    Highlights: Black-Right-Pointing-Pointer The unique hardening behavior on Ag-Pd-Au-Cu alloys by solution treatment was investigated. Black-Right-Pointing-Pointer The Cu-rich {alpha}{sub 1} phase and Ag-rich {alpha}{sub 2} phase decomposed by solution treatment contributed weakly to the change of hardness. Black-Right-Pointing-Pointer The fine {beta} phases precipitated by aging treatment caused great increase in hardness. Black-Right-Pointing-Pointer The fine L1{sub 0}-type ordered {beta} Prime phase precipitated by solution treatment may contribute to the unique hardening behavior. - Abstract: The objective of this research was to investigate the effect of constitutional phases on the unique hardening behavior of as-solutionized dental Ag-Pd-Au-Cu alloy fabricated by cold rolling. The commercial dental Ag-Pd-Au-Cu alloy fabricated by cold rolling consists of Cu-rich {alpha}{sub 1}, Ag-rich {alpha}{sub 2}, and {beta} phases. On the other hand, the Ag-Pd-Au-Cu alloy fabricated by the liquid rapid solidification (LRS) method consists of single {alpha} phase. They were subjected to various heat treatments, respectively. The microstructures were observed by scanning electron microscope, transmission electron microscope and X-ray diffraction. The hardness was evaluated by a Vickers micro-hardness tester. In the Ag-Pd-Au-Cu alloy fabricated by cold rolling, the fine L1{sub 0}-type-ordered {beta} Prime phase is precipitated and the coarse {beta} phase is remained after solution treatment at 1123 K. The hardness increases drastically. On the other hand, in the Ag-Pd-Au-Cu alloy fabricated by LRS method, the single {alpha} phase was decomposed into the {alpha}{sub 1} phase and the {alpha}{sub 2} phase after solution treatment at 1023 K and its hardness change was small. However, after aging treatment at 673 K, the fine {beta} phase is precipitated in the {alpha} phase and the hardness increases greatly even in the Ag-Pd-Au-Cu alloy fabricated by LRS method. It is considered

  10. Interrelationships of morphology, thermal and mechanical properties in uncrosslinked and dynamically crosslinked PP/EOC and PP/EPDM blends

    Directory of Open Access Journals (Sweden)

    2010-04-01

    Full Text Available Thermoplastic vulcanizates (TPVs based on polypropylene (PP with ethylene octene copolymer (EOC and ethylene propylene diene rubber (EPDM have been developed by coagent assisted dicumyl peroxide crosslinking system. The study was pursued to explore the influence of two dissimilar polyolefin polymers (EOC and EPDM having different molecular architectures on the state and mode of dispersion of the blend components and their effects with special reference to morphological, thermal and mechanical characteristics. The effects of dynamic crosslinking of the PP/EOC and PP/EPDM have been compared by varying the concentration of crosslinking agent and ratio of blend components. The results suggested that the uncrosslinked and dynamically crosslinked blends of PP/EOC exhibit superior mechanical properties over PP/EPDM blends. From the hystersis experiments it was found that PP/EOC blends also perform better fatigue properties over PP/EPDM based blends. It was demonstrated that, the origin of the improved mechanical properties of EOC based blends is due to the combined effect of the unique molecular architecture with the presence of smaller crystals and better interfacial interaction of EOC phase with PP as supported by the results of thermal and fatigue analyses.

  11. Thermal stabilities and decomposition mechanism of amino- and hydroxyl-functionalized ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Zhimin; Zhang, Yuwei [Department of Chemistry, Renmin University of China, Beijing 100872 (China); Zhou, Xiao-qin [College of Chemistry, Qufu Normal University, Shandong, Qufu 273165 (China); Cao, Yuanyuan [Department of Chemistry, Renmin University of China, Beijing 100872 (China); Mu, Tiancheng, E-mail: tcmu@chem.ruc.edu.cn [Department of Chemistry, Renmin University of China, Beijing 100872 (China)

    2014-02-01

    Highlights: • The long term thermal stabilities of [C{sub 2}NH{sub 2}MIM][Br] and [C{sub 3}OHMIM][Cl] are overestimated. • The thermal decomposition mechanisms of [C{sub 2}NH{sub 2}MIM][Br] and [C{sub 3}OHMIM][Cl] are complicated. • Bimolecular nucleophilic substitution (SN2) is the main reaction mechanism. - Abstract: Thermal stabilities and thermal decomposition mechanisms of amino-functionalized ionic liquid (IL) 1-aminoethyl-3-methylimidazolium bromide ([C{sub 2}NH{sub 2}MIM][Br]) and hydroxyl-functionalized IL 1-hydropropyl-3-methylimidazolium chloride ([C{sub 3}OHMIM][Cl]) were investigated by thermogravimetric analysis (TGA), TG–mass spectroscopy (TG–MS), density functional theory (DFT), and nuclear magnetic resonance (NMR) spectrum. Results show that the [C{sub 2}NH{sub 2}MIM][Br] and [C{sub 3}OHMIM][Cl] are stable up to 200 °C and 220 °C, respectively. Also, DFT calculation indicates that the thermal decomposition mechanisms of [C{sub 2}NH{sub 2}MIM][Br] and [C{sub 3}OHMIM][Cl] are complicated, while bimolecular nucleophilic substitution (SN2) is the main reaction mechanism. TG–MS and NMR spectra further prove the mechanisms.

  12. The NPP and J1 NOAA Unique Combined Atmospheric Processing System (NUCAPS) for atmospheric thermal sounding: recent algorithm enhancements tailored to near real time users applications.

    Science.gov (United States)

    Gambacorta, A.; Barnet, C. D.; Smith, N.; Pierce, R. B.; Smith, J. W.; Spackman, J. R.; Goldberg, M.

    2016-12-01

    NUCAPS is the NOAA operational algorithm to retrieve thermodynamic variables from hyper spectral thermal sounders such as CrIS on NPP and J1, IASI on MetOp and AIRS on Aqua, in conjunction with microwave sounders, such as ATMS, AMSU and MHS. NUCAPS builds on a long-term, multi-agency investment on algorithm research and development. The uniqueness of this algorithm consists in a number of features that are key in providing highly accurate and stable atmospheric retrievals, suitable for both real time weather and long-term climate applications. NUCAPS is an all-weather, full column and high vertical resolution system compatible with multiple hyper spectral sounders. This design was intended to enable multiple, global yet consistent daily measurements of the full atmospheric state and plays a critical role in filling in for the NWS in-situ measurement gaps, particularly during the early afternoon pre-convective and fast developing regimes. We are now developing the capability to run a Lagrangian transport model that can collocate NUCAPS thermodynamic fields to surface wind fields and propagate NUCAPS moist and dry layers in time and space. This is key to enhance a forecaster's predictive knowledge of what sources are at play in the evolution or suppression of convective or fire events. NUCAPS has proven robust in capturing extreme and high impact weather events during previously held JPSS PGRR initiatives, such as the 2015 CalWater, the 2016 Hazardous Test bed Spring Experiment, SENEX, SONGNEX and the 2016 El Nino Rapid Response campaign. Results from these initiatives will be presented at the meeting.

  13. Mechanisms Underpinning Degradation of Protective Oxides and Thermal Barrier Coatings in High Hydrogen Content (HHC) - Fueled Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Mumm, Daniel

    2013-08-31

    /thermo-chemical attack mechanisms; (iv) developing a mechanics-based analysis of the driving forces for crack growth and delamination, based on molten phase infiltration, misfit upon cooling, and loss of compliance; (v) understanding changes in TGO growth mechanisms associated with these emerging combustion product streams; and (vi) identifying degradation resistant alternative materials (including new compositions or bi-layer concepts) for use in mitigating the observed degradation modes. To address the materials stability concerns, this program integrated research thrusts aimed at: (1) Conducting tests in simulated syngas and HHC environments to evaluate materials evolution and degradation mechanisms; assessing thermally grown oxide development unique to HHC environmental exposures; carrying out high-resolution imaging and microanalysis to elucidate the evolution of surface deposits (molten phase formation and infiltration); exploring thermo-chemical instabilities; assessing thermo-mechanical drivers and thermal gradient effects on degradation; and quantitatively measuring stress evolution due to enhanced sintering and thermo-chemical instabilities induced in the coating. (2) Executing experiments to study the melting and infiltration of simulated ash deposits, and identifying reaction products and evolving phases associated with molten phase corrosion mechanisms; utilizing thermal spray techniques to fabricate test coupons with controlled microstructures to study mechanisms of instability and degradation; facilitating thermal gradient testing; and developing new materials systems for laboratory testing; (3) Correlating information on the resulting combustion environments to properly assess materials exposure conditions and guide the development of lab-scale simulations of material exposures; specification of representative syngas and high-hydrogen fuels with realistic levels of impurities and contaminants, to explore differences in heat transfer, surface degradation, and deposit

  14. p53 hypersensitivity is the predominant mechanism of the unique responsiveness of testicular germ cell tumor (TGCT cells to cisplatin.

    Directory of Open Access Journals (Sweden)

    Matthias Gutekunst

    Full Text Available Consistent with the excellent clinical results in testicular germ cell tumors (TGCT, most cell lines derived from this cancer show an exquisite sensitivity to Cisplatin. It is well accepted that the high susceptibility of TGCT cells to apoptosis plays a central role in this hypersensitive phenotype. The role of the tumor suppressor p53 in this response, however, remains controversial. Here we show that siRNA-mediated silencing of p53 is sufficient to completely abrogate hypersensitivity not only to Cisplatin but also to non-genotoxic inducers of p53 such as the Mdm2 antagonist Nutlin-3 and the proteasome inhibitor Bortezomib. The close relationship between p53 protein levels and induction of apoptosis is lost upon short-term differentiation, indicating that this predominant pro-apoptotic function of p53 is unique in pluripotent embryonal carcinoma (EC cells. RNA interference experiments as well as microarray analysis demonstrated a central role of the pro-apoptotic p53 target gene NOXA in the p53-dependent apoptotic response of these cells. In conclusion, our data indicate that the hypersensitivity of TGCT cells is a result of their unique sensitivity to p53 activation. Furthermore, in the very specific cellular context of germ cell-derived pluripotent EC cells, p53 function appears to be limited to induction of apoptosis.

  15. Thermal and mechanical interfacial properties of the DGEBA/PMR-15 blend system.

    Science.gov (United States)

    Park, Soo-Jin; Lee, Hwa-Young; Han, Mijeong; Hong, Sung-Kwon

    2004-02-15

    In this work, the blend system of diglycidyl ether of bisphenol A and PMR-15 polyimide is investigated in terms of thermal and dynamic mechanical interfacial properties of the casting specimens. The thermal stabilities are studied by thermogravimetric and thermomechanical analyses, and the dynamic mechanical properties are carried out by dynamic mechanical analysis. The results show that the thermal stabilities based on the initial decomposition temperature, the integral procedural decomposition temperature, and the glass transition temperature are increased with increasing PMR-15 content. The crosslinking density (rho) of the blend system is increased at 10 phr of PMR-15, compared with that of neat epoxy. Mechanical interfacial properties measured in the context of critical stress intensity factor and critical strain energy release rate show similar behaviors with E(a) and rho, probably due to the increase in intermolecular interactions or hydrogen bondings in polymer chains.

  16. Thermo-mechanical properties of carbon nanotubes and applications in thermal management

    Science.gov (United States)

    Nguyen, Manh Hong; Thang Bui, Hung; Trinh Pham, Van; Phan, Ngoc Hong; Nguyen, Tuan Hong; Chuc Nguyen, Van; Quang Le, Dinh; Khoi Phan, Hong; Phan, Ngoc Minh

    2016-06-01

    Thanks to their very high thermal conductivity, high Young’s modulus and unique tensile strength, carbon nanotubes (CNTs) have become one of the most suitable nano additives for heat conductive materials. In this work, we present results obtained for the synthesis of heat conductive materials containing CNT based thermal greases, nanoliquids and lubricating oils. These synthesized heat conductive materials were applied to thermal management for high power electronic devices (CPUs, LEDs) and internal combustion engines. The simulation and experimental results on thermal greases for an Intel Pentium IV processor showed that the thermal conductivity of greases increases 1.4 times and the saturation temperature of the CPU decreased by 5 °C by using thermal grease containing 2 wt% CNTs. Nanoliquids containing CNT based distilled water/ethylene glycol were successfully applied in heat dissipation for an Intel Core i5 processor and a 450 W floodlight LED. The experimental results showed that the saturation temperature of the Intel Core i5 processor and the 450 W floodlight LED decreased by about 6 °C and 3.5 °C, respectively, when using nanoliquids containing 1 g l-1 of CNTs. The CNTs were also effectively utilized additive materials for the synthesis of lubricating oils to improve the thermal conductivity, heat dissipation efficiency and performance efficiency of engines. The experimental results show that the thermal conductivity of lubricating oils increased by 12.5%, the engine saved 15% fuel consumption, and the longevity of the lubricating oil increased up to 20 000 km by using 0.1% vol. CNTs in the lubricating oils. All above results have confirmed the tremendous application potential of heat conductive materials containing CNTs in thermal management for high power electronic devices, internal combustion engines and other high power apparatus.

  17. Effect of thermal treatment on mechanically milled cobalt powder

    CSIR Research Space (South Africa)

    Bolokang, AS

    2012-03-01

    Full Text Available powder metallurgical route. In is the modern trend that nanocrystalline powders are used to improve the strength of cemented carbides [18-20]. Therefore, alloyed nanocrystalline carbide powders have been synthesized using MM technique [21, 22], while... caused by thin flakes of welded fine particles induced during mechanical deformation, but even after MM the powder remains a mixture of nanocrystalline and amorphous. The estimated crystalline size calculated using Sheerrer equation show that 8 and 25...

  18. Mechanism of low thermal conductivity of xonotlite-silica aerogel nanoporous super insulation material

    Institute of Scientific and Technical Information of China (English)

    Hailong Yang; Wen Ni; Deping Chen; Guoqiang Xu; Tao Liang; Li Xu

    2008-01-01

    In an effort to incorporate the low thermal conductivity of the silica aerogel and the superior structure strength of the xonotlite, a composite material of these two was produced. It was synthesized under vacuum condition and dried by supercritical drying technique. The thermal conductivity of the new material, which is at 298 K with the gas pressure ranging from 1.01×105 to 1× 10-2 Pa, was measured using the transient hot-strip method. The mechanism of the low thermal conductivity was studied. The re-suits indicate that the low thermal conductivity mainly results from the significant decrease of gaseous thermal conductivity of the new material due to the restriction of the motion of gas molecules in its fine structures. The formation of the fine structures is be-cause the new material takes the pore structure of the silica aerogel which consists of mainly nanometer-sized pores.

  19. Design and Development of a Solar Thermal Collector with Single Axis Solar Tracking Mechanism

    Directory of Open Access Journals (Sweden)

    Theebhan Mogana

    2016-01-01

    Full Text Available The solar energy is a source of energy that is abundant in Malaysia and can be easily harvested. However, because of the rotation of the Earth about its axis, it is impossible to harvest the solar energy to the maximum capacity if the solar thermal collector is placed fix to a certain angle. In this research, a solar thermal dish with single axis solar tracking mechanism that will rotate the dish according to the position of the sun in the sky is designed and developed, so that more solar rays can be reflected to a focal point and solar thermal energy can be harvested from the focal point. Data were collected for different weather conditions and performance of the solar thermal collector with a solar tracker were studied and compared with stationary solar thermal collector.

  20. Thermal depolymerization mechanisms of poly(3-hydroxybutyrate-co-3-hydroxyvalerate

    Directory of Open Access Journals (Sweden)

    Hengxue Xiang

    2016-02-01

    Full Text Available Thermal degradation processes and decomposition mechanisms of poly(3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV were investigated by using thermal gravity analysis(TGA, Gel permeation chromatography (GPC, elemental analyzer, pyrolysis-gas chromatography-mass spectrometry (PyGC-MS and 1H nuclear magnetic resonance (1H NMR. The degradation activation energy was calculated via the dependence of residual mass on isothermal temperature. 1H NMR and PyGC-MS were used to investigate the chemical structure and component proportion of volatile gases and degradation residues which were produced by thermal decomposition, and to infer the process of macromolecular chain scission. Besides, the influence of the factors, such as outfield atmosphere, residual metal ions, on the degradation behaviors of PHBV was also studied. Finally, the PHBV thermal decomposition mechanisms were speculated on the basis of the degradation behaviors of molecular and chemical structure.

  1. Effect of thermal ageing on mechanical properties of a high-strength ODS alloy

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Sung Hoon; Kim, Sung Hwan; Jang, Chang Heui [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of); Kim, Tae Kyu [Nuclear Materials DivisionKorea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    A new high-strength ODS alloy, ARROS, was recently developed for the application as the cladding material of a Sodium-cooled fast reactor (SFR). To assess the long-term integrity under thermal ageing, ARROS was thermally aged in air at 650°C for 1000 h. The degree of thermal ageing was assessed by mechanical tests such as uniaxial tensile, hardness, and small punch tests at from room temperature to 650°C. Tensile strength was slightly decreased but elongation, hardness, and small punch energy were hardly changed at all test temperatures for the specimen aged at 650°C for 1000 h. However, the variation in mechanical properties such as hardness and small punch energy increased after thermal ageing. Using the test results, the correlation between tensile strength and maximum small punch load was established.

  2. Thermal depolymerization mechanisms of poly (3-hydroxybutyrate-co-3-hydroxyvalerate)

    Institute of Scientific and Technical Information of China (English)

    Hengxue Xiang; Xiaoshuang Wen; Xiaohui Miu; Yan Li; Zhe Zhou; Meifang Zhu

    2016-01-01

    Thermal degradation processes and decomposition mechanisms of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) were investigated by using thermal gravity analysis(TGA), Gel permeation chromatography (GPC), elemental analyzer, pyrolysis-gas chromatography-mass spectrometry (PyGC-MS) and 1H nuclear magnetic resonance (1H NMR). The degradation activation energy was calculated via the dependence of residual mass on isothermal temperature. 1H NMR and PyGC-MS were used to investigate the chemical structure and component proportion of volatile gases and degradation residues which were produced by thermal decomposition, and to infer the process of macromolecular chain scission. Besides, the influence of the factors, such as outfield atmosphere, residual metal ions, on the degradation behaviors of PHBV was also studied. Finally, the PHBV thermal decomposition mechanisms were speculated on the basis of the degradation behaviors of molecular and chemical structure.

  3. Simultaneously Coupled Mechanical-Electrochemical-Thermal Simulation of Lithium-Ion Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chao; Santhanagopalan, Shriram; Sprague, Michael A.; Pesaran, Ahmad A.

    2016-08-01

    Understanding the combined electrochemical-thermal and mechanical response of a system has a variety of applications, for example, structural failure from electrochemical fatigue and the potential induced changes of material properties. For lithium-ion batteries, there is an added concern over the safety of the system in the event of mechanical failure of the cell components. In this work, we present a generic multi-scale simultaneously coupled mechanical-electrochemical-thermal model to examine the interaction between mechanical failure and electrochemical-thermal responses. We treat the battery cell as a homogeneous material while locally we explicitly solve for the mechanical response of individual components using a homogenization model and the electrochemical-thermal responses using an electrochemical model for the battery. A benchmark problem is established to demonstrate the proposed modeling framework. The model shows the capability to capture the gradual evolution of cell electrochemical-thermal responses, and predicts the variation of those responses under different short-circuit conditions.

  4. The mechanism of foaming and thermal conductivity of glasses foamed with MnO2

    DEFF Research Database (Denmark)

    Petersen, Rasmus Rosenlund; König, Jakob; Yue, Yuanzheng

    2015-01-01

    bubbles and subsequent growth. We discuss evolution of pore morphology in terms of pore number density, pore size and closed porosity. The thermal conductivity of the foam glasses is linearly dependent on density. The heat transfer mechanism is revealed by comparing the experimental data with structural...... data and analytical models.We show that the effect of pore size, presence of crystal inclusions and degree of closed porosity do not affect the overall thermal conductivity....

  5. Millisecond dynamics of thermal expansion of mechanically controllable break junction electrodes studied in the tunneling regime

    Science.gov (United States)

    Kolesnychenko, O. Yu.; Toonen, A. J.; Shklyarevskii, O. I.; van Kempen, H.

    2001-10-01

    The thermal expansion dynamics of W, Pt-Ir, and Au mechanically controllable break junction electrodes was studied in the millisecond range. By measuring a transient tunnel current as a function of time, we found that, at low temperatures, the electrode elongation Δs˜t1/2 due to the large values of thermal diffusivity of metals. The magnitude of Δs varies in direct proportion to the power P dissipated in the electrodes.

  6. Mechanism and Kinetic Parameters of Thermal Decomposition of Cobalt Dichloride Hexahydrate

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The thermal decomposition of the cobalt dichloride hexahydrate and its kinetics were studied by TG and DTG technique under the non-isothermal condition with nitrogen atnosphere.The non-isothermal kinetic data and kinetic parameters were evaluated by means of integral and differential methods.The most probable mechanism functions of the thermal decomposition reaction for the first stage are:f(α)=(1-α)2 and g(α)=(1-α)-1-1.

  7. Novel Porous Polymorphs of Zinc Cyanide with Rich Thermal and Mechanical Behavior

    OpenAIRE

    2015-01-01

    We investigate the feasibility of four-connected nets as hypothetical zinc cyanide polymorphs, as well as their thermal and mechanical properties, through quantum chemical calculations and molecular dynamics simulations. We confirm the metastability of the two porous phases recently discovered experimentally (Lapidus, S. H.; et al. J. Am. Chem. Soc. 2013, 135, 7621-7628), suggest the existence of seven novel porous phases of Zn(CN)2, and show that isotropic negative thermal expansion is a com...

  8. Catastrophe mechanism & classification of discontinuity behavior in thermal science (Ⅰ) --Fold catastrophe

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The mechanism of discontinuity behavior has important significance in the study of thermal science,such as fire,combustion,explosion and heat transfer.This sort of discontinuity behavior and the catastrophe caused by system nonlinearity may be equivalently classified according to the catastrophe model promulgated by catastrophe theory.Under the conditions of uniform temperature and thermal isolation,the self-ignition behavior of a Semenov System can be viewed as a result of the fold catastrophe of the system.

  9. Thermal protection mechanism of heat pipe in leading edge under hypersonic conditions

    OpenAIRE

    Peng Wengen; He Yurong; Wang Xinzhi; Zhu Jiaqi; Han Jiecai

    2015-01-01

    Sharp local structure, like the leading edge of hypersonic aircraft, confronts a severe aerodynamic heating environment at a Mach number greater than 5. To eliminate the danger of a material failure, a semi-active thermal protection system is proposed by integrating a metallic heat pipe into the structure of the leading edge. An analytical heat-balance model is established from traditional aerodynamic theories, and then thermal and mechanical characteristics of the structure are studied at Ma...

  10. Thermal fluctuations affect the transcriptome through mechanisms independent of average temperature.

    Science.gov (United States)

    Sørensen, Jesper Givskov; Schou, Mads Fristrup; Kristensen, Torsten Nygaard; Loeschcke, Volker

    2016-08-04

    Terrestrial ectotherms are challenged by variation in both mean and variance of temperature. Phenotypic plasticity (thermal acclimation) might mitigate adverse effects, however, we lack a fundamental understanding of the molecular mechanisms of thermal acclimation and how they are affected by fluctuating temperature. Here we investigated the effect of thermal acclimation in Drosophila melanogaster on critical thermal maxima (CTmax) and associated global gene expression profiles as induced by two constant and two ecologically relevant (non-stressful) diurnally fluctuating temperature regimes. Both mean and fluctuation of temperature contributed to thermal acclimation and affected the transcriptome. The transcriptomic response to mean temperatures comprised modification of a major part of the transcriptome, while the response to fluctuations affected a much smaller set of genes, which was highly independent of both the response to a change in mean temperature and to the classic heat shock response. Although the independent transcriptional effects caused by fluctuations were relatively small, they are likely to contribute to our understanding of thermal adaptation. We provide evidence that environmental sensing, particularly phototransduction, is a central mechanism underlying the regulation of thermal acclimation to fluctuating temperatures. Thus, genes and pathways involved in phototransduction are likely of importance in fluctuating climates.

  11. Phase lag deduced information in photo-thermal actuation for nano-mechanical systems characterization

    Energy Technology Data Exchange (ETDEWEB)

    Bijster, R. J. F., E-mail: roy.bijster@tno.nl; Vreugd, J. de [Department of Optomechatronics, TNO, Stieltjesweg 1, 2628 CK Delft (Netherlands); Sadeghian, H. [Department of Optomechatronics, TNO, Stieltjesweg 1, 2628 CK Delft (Netherlands); Department of Precision and Microsystems Engineering, Delft University of Technology, 2628 CD Delft (Netherlands)

    2014-08-18

    In photo-thermal actuation, heat is added locally to a micro-cantilever by means of a laser. A fraction of the irradiation is absorbed, yielding thermal stresses and deformations in the structure. Harmonic modulation of the laser power causes the cantilever to oscillate. Moreover, a phase lag is introduced which is very sensitive to the spot location and the cantilever properties. This phase lag is theoretically predicted and experimentally verified. Combined with thermo-mechanical properties of the cantilever and its geometry, the location of the laser spot, the thermal diffusivity, and the layer thicknesses of the cantilever can be extracted.

  12. Microstructural evolution and mechanical properties of Inconel 718 after thermal exposure

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Z.S., E-mail: yuzaisong@tpri.com.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, No. 28, Xianning West Road, Xi’an 710049 (China); Xi' an Thermal Power Research Institute Co. Ltd., No. 136, Xingqing Road, Xi’an 710032 (China); Zhang, J.X. [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, No. 28, Xianning West Road, Xi’an 710049 (China); Yuan, Y.; Zhou, R.C.; Zhang, H.J.; Wang, H.Z. [Xi' an Thermal Power Research Institute Co. Ltd., No. 136, Xingqing Road, Xi’an 710032 (China)

    2015-05-14

    Inconel 718 was subjected to various heat treatments, i.e., solution heat treatment, standard ageing treatment and standard ageing plus 700 °C thermal exposure. The mechanical properties of the alloys were determined using tensile tests and Charpy pendulum impact tests at 650 °C and room temperature, respectively. The highest yield strength of 988 MPa was attained in the standard aged specimen, whereas a maximum impact toughness of 217 J cm{sup −2} was attained in the solution-treated specimen. After thermal exposure, the mechanical properties of the specimens degrade. Both the yield strength and impact toughness decreased monotonically with increasing thermal exposure time. Subjected to a 10000-h long-term thermal exposure, the yield strength dramatically decreased to 475 MPa (almost 50% of the maximum strength), and the impact toughness reduced to only 18 J cm{sup −2}. The microstructures of the specimens were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Coarsening of γ′ and γ″ and the transformation of γ″ to δ-Ni{sub 3}Nb was observed after thermal exposure. However, a complete transformation from metastable γ″ to δ-Ni{sub 3}Nb was never accomplished, even after the 10000-h long-term thermal exposure. Based on the obtained experimental results, the effects of the microstructural evolution on the mechanical properties are discussed.

  13. Genome, transcriptome, and secretome analysis of wood decay fungus Postia placenta supports unique mechanisms of lignocellulose conversion

    Science.gov (United States)

    Diego Martinez; Jean Challacombe; Ingo Morgenstern; David Hibbett; Monika Schmoll; Christian P. Kubicek; Patricia Ferreira; Francisco J. Ruiz-Duenas; Angel T. Martinez; Philip J. Kersten; Kenneth E. Hammel; Jill A. Gaskell; Daniel Cullen

    2009-01-01

    Brown-rot fungi such as Postia placenta are common inhabitants of forest ecosystems and are also largely responsible for the destructive decay of wooden structures. Rapid depolymerization of cellulose is a distinguishing feature of brown-rot, but the biochemical mechanisms and underlying genetics are poorly understood. Systematic examination of the P. placenta genome,...

  14. Probabilistic fracture mechanics analysis of thermally aged nuclear piping in a pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shuxiao; Zhang, Hailong; Li, Shilei; Wang, Yanli [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Xue, Fei [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); Wang, Xitao, E-mail: xtwang@ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2013-12-15

    Highlights: • Thermal aging embrittlement was considered in the PFM analysis of nuclear pipe. • Predicting program for pipe failure probability was developed based on thermal aging. • Cumulative failure probability is significantly affected by fracture toughness. • Cumulative failure probability is slightly affected by fatigue crack growth rate. • Tensile strength increase due to thermal aging slightly reduces pipe failure risk. - Abstract: A predicting program for pipe break probability based on thermal aging embrittlement was developed. In order for life prediction, evolutions of fracture toughness and tensile strength were estimated for a Z3CN20-09M piping steel using the Argonne National Laboratory (ANL) procedure. To understand the influence of thermal aging on failure probability, different evolutions of fracture toughness, tensile strength and fatigue crack growth rate were employed in the prediction of cumulative failure probability. The results show that the cumulative failure probability for 40-year thermal aging increases by almost four times compared to without consideration of fracture toughness degradation. The cumulative failure probability is slightly affected by fatigue crack growth rate. The increase of tensile strength due to thermal aging reduces the risk of pipe failure. This work demonstrates that the degradation of fracture toughness due to thermal aging should be fully considered in the probabilistic fracture mechanics analysis of nuclear pressure pipes.

  15. Fine coal dewatering enhancement using mechanical thermal techniques

    Energy Technology Data Exchange (ETDEWEB)

    Patwardhan, A.; Mondal, K.; Chugh, Y.P.; Ping, H.; Singh, N. [Southern Illinois University-Carbondale, Carbondale, IL (USA). Department of Mining & Mineral Resources Engineering

    2002-07-01

    Studies were conducted in a laboratory pressure filter to evaluate and enhance the dewatering potential of thickener underflow samples from two operating coal mines in Illinois mining the No. 6 and No. 5 seams. Physical properties such as, size distribution, zeta potential variation with pH, microstructure and particle shape and ash content were characterized. In addition cake microstructure data was obtained through scanning electron microscopy. Experiments were conducted at a pressure of 42 psig. The initial solids content was varied from 8 to 30% to determine the impact of initial solids concentration on dewatering performance. A host of chemical treatments involving different surfactants and electrolytes were evaluated. In addition, mechanical agitation of cake and hot water treatment of the slurry was attempted. The introduction of copper ions into the slurry resulted in enhanced filtration rates due to reduced specific resistance to filtrate flow and increased porosity of the cake. Use of cationic and anionic surfactants reduced the total residual moisture by over 4%. The combined effect of a surfactant and copper ion resulted in further reduction in cake moisture along with significant improvement in dewatering rates. Elevating the temperature of the slurry to 55{degree}C showed only a slight improvement in filtration rate but produced the most compact cake with the lowest moisture content. Significant improvement in the dewatering kinetics from addition of electrolytes was also observed for the Illinois No. 5 seam sample. Statistical analysis of experimental data indicates dewatering enhancements as a result of electrolyte addition, hot water treatment and mechanical agitation. 20 refs., 5 figs., 7 tabs.

  16. Local thermal property analysis by scanning thermal microscopy of an ultrafine-grained copper surface layer produced by surface mechanical attrition treatment

    Energy Technology Data Exchange (ETDEWEB)

    Guo, F.A. [Suzhou Institute for Nonferrous Metals Processing Technology, No. 200 Shenxu Road, Suzhou Industrial Park, Suzhou 215021 (China) and Unite de Thermique et d' Analyse Physique, Laboratoire d' Energetique et d' Optique, Universite de Reims, BP 1039, 51687 Reims Cedex 2 (France)]. E-mail: guofuan@yahoo.com; JI, Y.L. [Suzhou Institute for Nonferrous Metals Processing Technology, No. 200 Shenxu Road, Suzhou Industrial Park, Suzhou 215021 (China); Trannoy, N. [Unite de Thermique et d' Analyse Physique, Laboratoire d' Energetique et d' Optique, Universite de Reims, BP 1039, 51687 Reims Cedex 2 (France); Lu, J. [LASMIS, Universite de Technologie de Troyes, 12 Rue Marie Curie, Troyes 10010 (France)

    2006-06-15

    Scanning thermal microscopy (SThM) was used to map thermal conductivity images in an ultrafine-grained copper surface layer produced by surface mechanical attrition treatment (SMAT). It is found that the deformed surface layer shows different thermal conductivities that strongly depend on the grain size of the microstructure: the thermal conductivity of the nanostructured surface layer decreases obviously when compared with that of the coarse-grained matrix of the sample. The role of the grain boundaries in thermal conduction is analyzed in correlation with the heat conduction mechanism in pure metal. A theoretical approach, based on this investigation, was used to calculate the heat flow from the probe tip to the sample and then estimate the thermal conductivities at different scanning positions. Experimental results and theoretical calculation demonstrate that SThM can be used as a tool for the thermal property and microstructural analysis of ultrafine-grained microstructures.

  17. Experimental Study on the Thermal Damage Characteristics of Limestone and Underlying Mechanism

    Science.gov (United States)

    Zhang, Weiqiang; Sun, Qiang; Hao, Shuqing; Wang, Bo

    2016-08-01

    This work discusses an experimental investigation on the thermal damage characteristics of limestone and underlying mechanism. Cylindrical rock samples were heated to a specific temperature level of 25, 100, 200, 300, 400, 500, 600, 700, 800, and 900 °C. Then the thermal damage evolution equation was established based on the experimental results and the characteristics of thermal damage were analyzed. Last, possible mechanisms for the observed thermo-physical and mechanical response are discussed. The results show that with the increase of temperature in the tested range of temperature, the P-wave velocity, peak compressive strength and elastic modulus decrease, but the peak strain increases; the damage factors increase faster in 200-600 °C; the development of high-temperature-induced cracks conforms to the dislocation theory; the decomposition of magnesium carbonate and dolomite is the main reaction in the tested temperature range.

  18. A Phenomenological Thermal-Mechanical Viscoelastic Constitutive Modeling for Polypropylene Wood Composites

    Directory of Open Access Journals (Sweden)

    Xiongqi Peng

    2012-01-01

    Full Text Available This paper presents a phenomenological thermal-mechanical viscoelastic constitutive modeling for polypropylene wood composites. Polypropylene (PP wood composite specimens are compressed at strain rates from 10−4 to 10−2 s−1 and at temperature of , , and , respectively. The mechanical responses are shown to be sensitive both to strain rate and to temperature. Based on the Maxwell viscoelastic model, a nonlinear thermal-mechanical viscoelastic constitutive model is developed for the PP wood composite by decoupling the effect of temperature with that of the strain rate. Corresponding viscoelastic parameters are obtained through curve fitting with experimental data. Then the model is used to simulate thermal compression of the PP wood composite. The predicted theoretical results coincide quite well with experimental data. The proposed constitutive model is then applied to the thermoforming simulation of an automobile interior part with the PP wood composites.

  19. Additively manufactured metallic porous biomaterials based on minimal surfaces: A unique combination of topological, mechanical, and mass transport properties.

    Science.gov (United States)

    Bobbert, F S L; Lietaert, K; Eftekhari, A A; Pouran, B; Ahmadi, S M; Weinans, H; Zadpoor, A A

    2017-04-15

    Porous biomaterials that simultaneously mimic the topological, mechanical, and mass transport properties of bone are in great demand but are rarely found in the literature. In this study, we rationally designed and additively manufactured (AM) porous metallic biomaterials based on four different types of triply periodic minimal surfaces (TPMS) that mimic the properties of bone to an unprecedented level of multi-physics detail. Sixteen different types of porous biomaterials were rationally designed and fabricated using selective laser melting (SLM) from a titanium alloy (Ti-6Al-4V). The topology, quasi-static mechanical properties, fatigue resistance, and permeability of the developed biomaterials were then characterized. In terms of topology, the biomaterials resembled the morphological properties of trabecular bone including mean surface curvatures close to zero. The biomaterials showed a favorable but rare combination of relatively low elastic properties in the range of those observed for trabecular bone and high yield strengths exceeding those reported for cortical bone. This combination allows for simultaneously avoiding stress shielding, while providing ample mechanical support for bone tissue regeneration and osseointegration. Furthermore, as opposed to other AM porous biomaterials developed to date for which the fatigue endurance limit has been found to be ≈20% of their yield (or plateau) stress, some of the biomaterials developed in the current study show extremely high fatigue resistance with endurance limits up to 60% of their yield stress. It was also found that the permeability values measured for the developed biomaterials were in the range of values reported for trabecular bone. In summary, the developed porous metallic biomaterials based on TPMS mimic the topological, mechanical, and physical properties of trabecular bone to a great degree. These properties make them potential candidates to be applied as parts of orthopedic implants and/or as bone

  20. MWCNTs/Resin Nanocomposites: Structural, Thermal, Mechanical and Dielectric Investigation

    Directory of Open Access Journals (Sweden)

    N. D. Alexopoulos

    2015-11-01

    Full Text Available Multi-wall carbon nanotubes (MWCNTs were manufactured, characterized and added to a typical aeronautical resin matrix at different concentrations as nano-reinforcement. The carbon content of produced MWCNTs was determined to be around 98.5% while they consisted of 13-20 wall-layers and their external diameter had an average size in between 20 and 50 nm. MWCNTs were dispersed in an epoxy resin system and tensile specimens for different MWCNTs concentrations were prepared in an open mould. Electrical wiring was attached to the specimens’ surface and surface electrical resistance change was in-situ monitored during monotonic tension till fracture. Performed tensile tests showed that the MWCNTs addition increased both modulus of elasticity and ultimate tensile strength on the nano-composites with a simultaneously dramatic ductility decrease. The MWCNTs addition enhanced the investigated resin matrix with monitoring ability; electrical resistance change of the investigated tensile tests was correlated in the elastic regime with axial nominal strain and the gauge factor of the different MWCNTs concentration specimens were calculated. It was found that lowest MWCNTs concentration gave the best results in terms of piezo-resistivity and simultaneously the least enhancement in the mechanical properties.

  1. Life Prediction of Ball Grid Array Soldered Joints under Thermal Cycling Loading by Fracture Mechanics Method

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Fatigue crack propagation life of ball grid array (BGA) soldered joints during thermal cycling loading was investigated by fracture mechanics approach using finite element analysis. The relationships between the strain energy release rate (G) and crack size (α), thermal cycle numbers (N) can be derived. Based on the relationships, fatigue life of the soldered joints was determined. The results showed that crack propagation life was higher than crack initiation life. Therefore, it appears that it is more appropriate to predict the fatigue life of soldered joints using the fracture mechanics method.

  2. Thermal, dielectric and mechanical study of poly(vinyl chloride/olive pomace composites

    Directory of Open Access Journals (Sweden)

    2007-12-01

    Full Text Available Composites from PVC and chemically treated olive pomace have been prepared. The effect of the incorporation of virgin and benzylated olive pomace in the poly(vinyl chloride matrix on dielectric, mechanical and thermal stability properties, of /olive pomace composites was studied. The mechanical properties of the benzylated composites were improved. Furthermore, the thermal characterization of the different samples carried out by thermogravimetric analysis revealed an increase in the onset temperatures of decomposition for the treated composites. The dielectric investigation indicated that the samples containing olive pomace treated with the benzyl chloride can be used in electrical applications as insulators.

  3. Coupled Mechanical-Electrochemical-Thermal Modeling for Accelerated Design of EV Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Santhanagopalan, Shriram; Zhang, Chao; Kim, Gi-Heon; Pesaran, Ahmad A.

    2015-05-03

    This presentation provides an overview of the mechanical electrochemical-thermal (M-ECT) modeling efforts. The physical phenomena occurring in a battery are many and complex and operate at different scales (particle, electrodes, cell, and pack). A better understanding of the interplay between different physics occurring at different scales through modeling could provide insight to design improved batteries for electric vehicles. Work funded by the U.S. DOE has resulted in development of computer-aided engineering (CAE) tools to accelerate electrochemical and thermal design of batteries; mechanical modeling is under way. Three competitive CAE tools are now commercially available.

  4. Mechanical and Thermal Properties of Compression Molded Poly (acrylic acid) Salts with Multivalent Metal Ions

    OpenAIRE

    Gotoh, Y.; Ohkoshi, Y; Nagura, M

    1999-01-01

    Films of zinc, calcium and aluminum salts of poly (acrylic acid) (PAA) were prepared from their powdery salts by compression molding at 190_??_200°C, 600MPa for 0.5hr and their mechanical and thermal properties were investigated. From the results of the dynamic mechanical thermal analysis the storage modulus of each PAA salts exhibited about 20GPa at room temperature because of highly intermolecular crosslinking of PAA by metal ions. Modulus of PAA calcium salt was 7GPa even at 400°C, while m...

  5. Novel high-throughput screen identifies an HIV-1 reverse transcriptase inhibitor with a unique mechanism of action.

    Science.gov (United States)

    Sheen, Chih-Wei; Alptürk, Onur; Sluis-Cremer, Nicolas

    2014-09-15

    HIV-1 resistance to zidovudine [AZT (azidothymidine)] is associated with selection of the mutations M41L, D67N, K70R, L210W, T215F/Y and K219Q/E in RT (reverse transcriptase). These mutations decrease HIV-1 susceptibility to AZT by augmenting RT's ability to excise the chain-terminating AZT-MP (AZT-monophosphate) moiety from the chain-terminated DNA primer. Although AZT-MP excision occurs at the enzyme's polymerase active site, it is mechanistically distinct from the DNA polymerase reaction. Consequently, this activity represents a novel target for drug discovery, and inhibitors that target this activity may increase the efficacy of nucleoside/nucleotide analogues, and may help to delay the onset of drug resistance. In the present study, we have developed a FRET (Förster resonance energy transfer)-based high-throughput screening assay for the AZT-MP excision activity of RT. This assay is sensitive and robust, and demonstrates a signal-to-noise ratio of 3.3 and a Z' factor of 0.69. We screened three chemical libraries (7265 compounds) using this assay, and identified APEX57219 {3,3'-[(3-carboxy-4-oxo-2,5-cyclohexadien-1-ylidene)methylene]bis[6-hydroxybenzoic acid]} as the most promising hit. APEX57219 displays a unique activity profile against wild-type and drug-resistant HIV-1 RT, and was found to inhibit virus replication at the level of reverse transcription. Mechanistic analyses revealed that APEX57219 blocked the interaction between RT and the nucleic acid substrate.

  6. Effect of Isomorphous Substitution on the Thermal Decomposition Mechanism of Hydrotalcites

    Directory of Open Access Journals (Sweden)

    Sergio Crosby

    2014-10-01

    Full Text Available Hydrotalcites have many important applications in catalysis, wastewater treatment, gene delivery and polymer stabilization, all depending on preparation history and treatment scenarios. In catalysis and polymer stabilization, thermal decomposition is of great importance. Hydrotalcites form easily with atmospheric carbon dioxide and often interfere with the study of other anion containing systems, particularly if formed at room temperature. The dehydroxylation and decomposition of carbonate occurs simultaneously, making it difficult to distinguish the dehydroxylation mechanisms directly. To date, the majority of work on understanding the decomposition mechanism has utilized hydrotalcite precipitated at room temperature. In this study, evolved gas analysis combined with thermal analysis has been used to show that CO2 contamination is problematic in materials being formed at RT that are poorly crystalline. This has led to some dispute as to the nature of the dehydroxylation mechanism. In this paper, data for the thermal decomposition of the chloride form of hydrotalcite are reported. In addition, carbonate-free hydrotalcites have been synthesized with different charge densities and at different growth temperatures. This combination of parameters has allowed a better understanding of the mechanism of dehydroxylation and the role that isomorphous substitution plays in these mechanisms to be delineated. In addition, the effect of anion type on thermal stability is also reported. A stepwise dehydroxylation model is proposed that is mediated by the level of aluminum substitution.

  7. Effect of Mo content on thermal and mechanical properties of Mo–Ru–Rh–Pd alloys

    Energy Technology Data Exchange (ETDEWEB)

    Masahira, Yusuke [Division of Sustainable Energy and Environment Engineering, Graduate School of Engineering, Osaka University (Japan); Ohishi, Yuji, E-mail: ohishi@see.eng.osaka-u.ac.jp [Division of Sustainable Energy and Environment Engineering, Graduate School of Engineering, Osaka University (Japan); Kurosaki, Ken; Muta, Hiroaki [Division of Sustainable Energy and Environment Engineering, Graduate School of Engineering, Osaka University (Japan); Yamanaka, Shinsuke [Division of Sustainable Energy and Environment Engineering, Graduate School of Engineering, Osaka University (Japan); Research Institute of Nuclear Engineering, University of Fukui (Japan); Komamine, Satoshi; Fukui, Toshiki; Ochi, Eiji [Japan Nuclear Fuel Limited (Japan)

    2015-01-15

    Metallic inclusions are precipitated in irradiated oxide fuels. The composition of the phases varies with the burnup and the conditions such as temperature gradients and oxygen potential of the fuel. In the present work, Mo{sub x/(0.7+x)} (Ru{sub 0.5}Rh{sub 0.1}Pd{sub 0.1}){sub (0.7)/(0.7+x)} (x = 0, 0.05, 0.1, 0.15, 0.2, and 0.25) alloys were prepared by arc melting, followed by annealing in a high vacuum. The thermal and mechanical properties of the alloys such as elastic moduli, Debye temperature, micro-Vickers hardness, electrical resistivity, and thermal conductivity have been evaluated to elucidate the effect of Mo content on these physical properties of the alloys. The alloys with lower Mo contents show higher thermal conductivity. The thermal conductivity of the alloy with x = 0 is almost twice of that of the alloy with x = 0.25. The thermal conductivities of the alloys are dominated by electronic contribution, which has been evaluated using the Wiedemann–Franz–Lorenz relation from the electrical resistivity data. It is confirmed that the variation of the Mo contents of the alloys considerably affects the mechanical and thermal properties of the alloys.

  8. Mechanism of the Reduced Thermal Conductivity of Fishbone-Type Si Phononic Crystal Nanostructures

    Science.gov (United States)

    Nomura, M.; Maire, J.

    2015-06-01

    The mechanism of the reduced thermal conductivity of fishbone-type phononic crystal (PnC) nanostructures, in which ballistic phonon transport is dominant, was investigated with consideration of both the wave and particle nature of phonons. Phononic band diagrams were calculated for an Si nanowire and a fishbone-type PnC structure with a period of 100 nm, and a clear reduction of the group velocity of phonons, because of a zone-folding effect, was shown. Air-suspended Si nanowires and fishbone-type PnC structures were fabricated by electron beam (EB) lithography, and their thermal conductivities were measured by use of the originally developed micro time-domain thermoreflectance method. The PnC structure had a much lower thermal conductivity. We measured the thermal conductivity of a variety of PnC structures with different fin widths to investigate the mechanism of the reduced thermal conductivity observed. The result indicates that the increase of the phonon traveling distance. as a result of the fins, also results in reduced thermal conductivity.

  9. Degradation mechanisms of cable insulation materials during radiation-thermal ageing in radiation environment

    Science.gov (United States)

    Seguchi, Tadao; Tamura, Kiyotoshi; Ohshima, Takeshi; Shimada, Akihiko; Kudoh, Hisaaki

    2011-02-01

    Radiation and thermal degradation of ethylene-propylene rubber (EPR) and crosslinked polyethylene (XLPE) as cable insulation materials were investigated by evaluating tensile properties, gel-fraction, and swelling ratio, as well as by the infrared (FTIR) analysis. The activation energy of thermal oxidative degradation changed over the range 100-120 °C for both EPR and XLPE. This may be attributed to the fact that the content of an antioxidant used as the stabilizer for polymers decreases by evaporation during thermal ageing at high temperatures. The analysis of antioxidant content and oxidative products in XLPE as a model sample showed that a small amount of antioxidant significantly reduced the extent of thermal oxidation, but was not effective for radiation induced oxidation. The changes in mechanical properties were well reflected by the degree of oxidation. A new model of polymer degradation mechanisms was proposed where the degradation does not take place by chain reaction via peroxy radical and hydro-peroxide. The role of the antioxidant in the polymer is the reduction of free radical formation in the initiation step in thermal oxidation, and it could not stop radical reactions for either radiation or thermal oxidation.

  10. Degradation mechanisms of cable insulation materials during radiation-thermal ageing in radiation environment

    Energy Technology Data Exchange (ETDEWEB)

    Seguchi, Tadao, E-mail: seguchi@aj.wakwak.co [Japan Atomic Energy Agency, Tokai 319-1195 (Japan); Tamura, Kiyotoshi; Ohshima, Takeshi; Shimada, Akihiko [Japan Atomic Energy Agency, Tokai 319-1195 (Japan); Kudoh, Hisaaki [University of Tokyo, Tokai 319-1195 (Japan)

    2011-02-15

    Radiation and thermal degradation of ethylene-propylene rubber (EPR) and crosslinked polyethylene (XLPE) as cable insulation materials were investigated by evaluating tensile properties, gel-fraction, and swelling ratio, as well as by the infrared (FTIR) analysis. The activation energy of thermal oxidative degradation changed over the range 100-120 {sup o}C for both EPR and XLPE. This may be attributed to the fact that the content of an antioxidant used as the stabilizer for polymers decreases by evaporation during thermal ageing at high temperatures. The analysis of antioxidant content and oxidative products in XLPE as a model sample showed that a small amount of antioxidant significantly reduced the extent of thermal oxidation, but was not effective for radiation induced oxidation. The changes in mechanical properties were well reflected by the degree of oxidation. A new model of polymer degradation mechanisms was proposed where the degradation does not take place by chain reaction via peroxy radical and hydro-peroxide. The role of the antioxidant in the polymer is the reduction of free radical formation in the initiation step in thermal oxidation, and it could not stop radical reactions for either radiation or thermal oxidation.

  11. Ipsilateral simultaneous fracture of the trochlea involving the lateral end clavicle and distal end radius: a rare combination and a unique mechanism of injury

    Directory of Open Access Journals (Sweden)

    Gupta RK

    2014-07-01

    Full Text Available 【Abstract】Isolated trochlea fracture in adults is a rare surgical entity as compared to its capitellar counterpart. It has been only mentioned sporadically in the literature as case reports. Fracture of the trochlea is accompanied by other elbow injuries like elbow dislocation, capitellum fracture, ulnar fracture and extraarticular condylar fracture. Here we report a unique case of isolated displaced trochlea fracture associated with fractures of the lateral end clavicle and the distal end radius. We propose a unique mechanism for this rare combination of injuries: typical triad of injury, i.e. fracture of the distal end radius with trochlea and fracture of the lateral end of the clavicle. Nonoperative treatment is recommended for undisplaced humeral trochlea fractures; but for displaced ones, anatomical reduction and internal fixation are essential to maintain the congruous trochleacoronoid articulation and hence to maintain the intrinsic stability of the elbow. Key words: Isolated trochlea fracture; Clavicle; Radius fractures

  12. Thermal decomposition mechanisms of alkylimidazolium ionic liquids with cyano-functionalized anions.

    Science.gov (United States)

    Chambreau, Steven D; Schenk, Adam C; Sheppard, Anna J; Yandek, Gregory R; Vaghjiani, Ghanshyam L; Maciejewski, John; Koh, Christine J; Golan, Amir; Leone, Stephen R

    2014-11-26

    Because of the unusually high heats of vaporization of room-temperature ionic liquids (RTILs), volatilization of RTILs through thermal decomposition and vaporization of the decomposition products can be significant. Upon heating of cyano-functionalized anionic RTILs in vacuum, their gaseous products were detected experimentally via tunable vacuum ultraviolet photoionization mass spectrometry performed at the Chemical Dynamics Beamline 9.0.2 at the Advanced Light Source. Experimental evidence for di- and trialkylimidazolium cations and cyano-functionalized anionic RTILs confirms thermal decomposition occurs primarily through two pathways: deprotonation of the cation by the anion and dealkylation of the imidazolium cation by the anion. Secondary reactions include possible cyclization of the cation and C2 substitution on the imidazolium, and their proposed reaction mechanisms are introduced here. Additional evidence supporting these mechanisms was obtained using thermal gravimetric analysis-mass spectrometry, gas chromatography-mass spectrometry, and temperature-jump infrared spectroscopy. In order to predict the overall thermal stability in these ionic liquids, the ability to accurately calculate both the basicity of the anions and their nucleophilicity in the ionic liquid is critical. Both gas phase and condensed phase (generic ionic liquid (GIL) model) density functional theory calculations support the decomposition mechanisms, and the GIL model could provide a highly accurate means to determine thermal stabilities for ionic liquids in general.

  13. Numerical model for thermal and mechanical behaviour of a CANDU 37-element bundle

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, L.; MacKay, K. [Martec Limited, Halifax, Nova Scotia (Canada); Gibb, R. [Canadian Nuclear Safety Commission (CNSC), Ottawa, Ontario (Canada)

    2010-07-01

    Prediction of transient fuel bundle deformations is important for assessing the integrity of fuel and the surrounding structural components under different operating conditions including accidents. For numerical simulation of the interactions between fuel bundle and pressure tube, a reliable numerical bundle model is required to predict thermal and mechanical behaviour of the fuel bundle assembly under different thermal loading conditions. To ensure realistic representations of the bundle behaviour, this model must include all of the important thermal and mechanical features of the fuel bundle, such as temperature-dependent material properties, thermal viscoplastic deformation in sheath, fuel-to-sheath interactions, endplate constraints and contacts between fuel elements. In this paper, we present a finite element based numerical model for predicting macroscopic transient thermal-mechanical behaviour of a complete 37-element CANDU nuclear fuel bundle under accident conditions and demonstrate its potential for being used to investigate fuel bundle to pressure tube interaction in future nuclear safety analyses. This bundle model has been validated against available experimental and numerical solutions and applied to various simulations involving steady-state and transient loading conditions. (author)

  14. Effect of Functionalization of Graphene Nanoplatelets on the Mechanical and Thermal Properties of Silicone Rubber Composites

    Directory of Open Access Journals (Sweden)

    Guangwu Zhang

    2016-02-01

    Full Text Available This study investigated the effect of silane and surfactant treatments of graphene nanoplatelets (GnPs on the mechanical and thermal properties of silicone rubber (SR composites. GnPs were modified with aminopropyltriethoxysilane (APTES, vinyltrimethoxysilane (VTMS, and Triton X-100, and then the pristine GnPs and functionalized GnPs were individually incorporated into the SR. Compared with the pristine GnP/SR composite, the composites reinforced with modified GnP showed better tensile strength, elongation at break, and thermal conductivity properties due to better dispersion of modified GnPs and stronger interfacial interactions between the modified GnPs and matrix. The mechanical properties and thermal conductivity of the VTMS-GnP/SR composite were comparable to the properties of the Triton-GnP counterpart, but better than that of the APTES-GnP/SR composite. In addition, the VTMS-GnP/SR composite demonstrated the highest thermal stability and crystallization temperature among the four types of composites. The remarkable improvement of mechanical and thermal properties of the VTMS-GnP/SR composite was mainly due to the covalent linkage of VTMS-GnP with SR. The VTMS treatment was a more appropriate modification of GnP particles to improve the multifunctional properties of SR.

  15. Mechanical-Thermal Noise in Drive-Mode of a Silicon Micro-Gyroscope

    Directory of Open Access Journals (Sweden)

    Bailing Zhou

    2009-05-01

    Full Text Available A new closed-loop drive scheme which decouples the phase and the gain of the closed-loop driving system was designed in a Silicon Micro-Gyroscope (SMG. We deduce the system model of closed-loop driving and use stochastic averaging to obtain an approximate “slow” system that clarifies the effect of thermal noise. The effects of mechanical-thermal noise on the driving performance of the SMG, including the noise spectral density of the driving amplitude and frequency, are derived. By calculating and comparing the noise amplitude due to thermal noise both in the opened-loop driving and in the closed-loop driving, we find that the closed-loop driving does not reduce the RMS noise amplitude. We observe that the RMS noise frequency can be reduced by increasing the quality factor and the drive amplitude in the closed-loop driving system. The experiment and simulation validate the feasibility of closed-loop driving and confirm the validity of the averaged equation and its stablility criterion. The experiment and simulation results indicate the electrical noise of closed-loop driving circuitry is bigger than the mechanical-thermal noise and as the driving mass decreases, the mechanical-thermal noise may get bigger than the electrical noise of the closed-loop driving circuitry.

  16. Mechanical and thermal buckling analysis of rectangular sandwich panels under different edge conditions

    Science.gov (United States)

    Ko, William L.

    1994-01-01

    The combined load (mechanical or thermal load) buckling equations were established for orthotropic rectangular sandwich panels under four different edge conditions by using the Rayleigh-Ritz method of minimizing the total potential energy of a structural system. Two-dimensional buckling interaction curves and three-dimensional buckling interaction surfaces were constructed for high-temperature honeycomb-core sandwich panels supported under four different edge conditions. The interaction surfaces provide overall comparison of the panel buckling strengths and the domains of symmetrical and antisymmetrical buckling associated with the different edge conditions. In addition, thermal buckling curves of these sandwich panels are presented. The thermal buckling conditions for the cases with and without thermal moments were found to be identical for the small deformation theory.

  17. The Effect of Mechanical Load on the Thermal Conductivity of Building Materials

    Directory of Open Access Journals (Sweden)

    J. Toman

    2000-01-01

    Full Text Available The effect of mechanical load on the thermal conductivity of building materials in the design of envelope parts of building structures is studied. A typical building material is chosen in the practical investigation of this effect, namely the cement mortar. It is concluded that in the range of hygroscopic moisture content, lower levels of mechanical load, typically up to 90 % of compressive strength (CS, are not dangerous from the point of view of worsening the designed thermal properties, but in the overhygroscopic region, the load as low as 57 % of CS may be dangerous. The higher levels of loading are found to be always significant because they lead to marked increase of thermal conductivity which is always a negative information for a building designer.

  18. Improving methane production from digested manure biofibers by mechanical and thermal alkaline pretreatment.

    Science.gov (United States)

    Tsapekos, P; Kougias, Panagiotis G; Frison, A; Raga, R; Angelidaki, I

    2016-09-01

    Animal manure digestion is associated with limited methane production, due to the high content in fibers, which are hardly degradable lignocellulosic compounds. In this study, different mechanical and thermal alkaline pretreatment methods were applied to partially degradable fibers, separated from the effluent stream of biogas reactors. Batch and continuous experiments were conducted to evaluate the efficiency of these pretreatments. In batch experiments, the mechanical pretreatment improved the degradability up to 45%. Even higher efficiency was shown by applying thermal alkaline pretreatments, enhancing fibers degradability by more than 4-fold. In continuous experiments, the thermal alkaline pretreatment, using 6% NaOH at 55°C was proven to be the most efficient pretreatment method as the methane production was increased by 26%. The findings demonstrated that the methane production of the biogas plants can be increased by further exploiting the fraction of the digested manure fibers which are discarded in the post-storage tank.

  19. Improving methane production from digested manure biofibers by mechanical and thermal alkaline pretreatment

    DEFF Research Database (Denmark)

    Tsapekos, Panagiotis; Kougias, Panagiotis; Frison, A.

    2016-01-01

    Animal manure digestion is associated with limited methane production, due to the high content in fibers, which are hardly degradable lignocellulosic compounds. In this study, different mechanical and thermal alkaline pretreatment methods were applied to partially degradable fibers, separated from...... the effluent stream of biogas reactors. Batch and continuous experiments were conducted to evaluate the efficiency of these pretreatments. In batch experiments, the mechanical pretreatment improved the degradability up to 45%. Even higher efficiency was shown by applying thermal alkaline pretreatments......, enhancing fibers degradability by more than 4-fold. In continuous experiments, the thermal alkaline pretreatment, using 6% NaOH at 55 °C was proven to be the most efficient pretreatment method as the methane production was increased by 26%. The findings demonstrated that the methane production of the biogas...

  20. Thermal and mechanical analyses of high-speed permanent-magnet electrical machines

    Energy Technology Data Exchange (ETDEWEB)

    Kolondzovski, Z.

    2010-07-01

    In the thesis, methods for the thermal and mechanical analyses of high-speed PM electrical machines are presented and implemented. The first method implemented for the thermal analysis is a combined 2D-3D numerical method. The thermal and turbulent properties of the flow, such as the temperature rise in the flow and the coefficients of thermal convection, are estimated using a 2D multi physics method that couples CFD with heat-transfer equations. The detailed distribution of the temperature rise in the whole solid domain of the machine is determined using a 3D numerical heat-transfer method. The temperature rises in the machine are also estimated with the traditional thermal-network method, which uses a totally different approach to the heat-transfer analysis. The methods used for the mechanical analysis of the machine include finite-element rotordynamics modelling of the rotor for estimation of the critical speeds and the shapes of the bending modes and also analytical estimation of the stress in the retaining sleeve. The implemented methods are used for the comparative thermal and mechanical analyses of three different high-speed PM rotor constructions. The first type of rotor construction is retained with a carbon-fibre sleeve and uses a shield for eddy currents made of aluminium. The second rotor construction is retained with a retaining sleeve made from the alloy Ti-6%Al-6%V-2%Sn and the sleeve of the third rotor construction is made from the alloy Ti-2.5%Cu. The last two rotor constructions do not have separate eddy-current shields. The comparative analysis shows that the rotor with a carbon-fibre sleeve and an aluminium eddy-current shield shows the best thermal properties. The rotor with a retaining sleeve made of the titanium alloy Ti-6%Al-6%V-2%Sn offers promising thermal properties because the critical temperatures in the rotor are not exceeded. Additionally, the same rotor construction provides the best rotordynamics properties when compared to the

  1. MECHANICAL CHARACTERISTICS OF ENDOCARP AND KERNEL OF CASHEW NUT 'CCP 76' PRIOR AND POST THERMAL TREATMENT

    OpenAIRE

    De Araujo, MC; Ferraz, ACD

    2008-01-01

    Viscoelastic characteristics of raw cashew nut shell hinder its decortication by compression. In order to facilitate the shell opening and to liberate the kernel, nuts were subjected to hydration and thermal treatment in cashew nut shell liquid (CSL) at 210 degrees C. With the objective of developing more appropriate shelling mechanisms the cashew nut 'CCP 76' was characterized by its main dimensions, mass and volume, as well as mechanical behavior of the endocarp and kernel, prior and after ...

  2. Mechanical, thermal, and biodegradable properties of polylactic acid (PLA)/coir fibre biocomposites

    Science.gov (United States)

    Dong, Y.; Ghataura, A.; Haroosh, H. J.

    2013-08-01

    Polylactic acid (PLA)/coir fibre biocomposites were fabricated using a compression moulding technique. The effects of fibre content (5-30 wt%) and fibre treatment on mechanical, thermal and biodegradable properties of biocomposites were holistically investigated via mechanical testing, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and soil burial method to understand the applicability of manufacturing eco-efficient and sustainable "green composites".

  3. Thermal-Mechanical Properties of Polyurethane-Clay Shape Memory Polymer Nanocomposites

    Directory of Open Access Journals (Sweden)

    Arno Kraft

    2010-04-01

    Full Text Available Shape memory nanocomposites of polyurethane (PU-clay were fabricated by melt mixing of PU and nano-clay. Based on nano-indentation and microhardness tests, the strength of the nanocomposites increased dramatically as a function of clay content, which is attributed to the enhanced nanoclay–polymer interactions. Thermal mechanical experiments demonstrated good mechanical and shape memory effects of the nanocomposites. Full shape memory recovery was displayed by both the pure PU and PU-clay nanocomposites.

  4. Mechanism and Kinetics of Thermal Decomposition of MgCl2 × 6H2O

    Science.gov (United States)

    Huang, Qiong-Zhu; Lu, Gui-Min; Wang, Jin; Yu, Jian-Guo

    2010-10-01

    The reaction mechanism and kinetic behavior of thermal decomposition of MgCl2 × 6H2O were studied by thermal gravimetric analysis. The results showed that the thermal decomposition process of MgCl2 × 6H2O could be divided into six stages. In the first two stages, four crystalline waters were lost. The dehydration and hydrolysis coexisted during the third and fourth stages. The fifth stage corresponded to the evaporation of 0.3 crystalline waters, and one molecular hydrogen chloride was eliminated in the last stage. The kinetic analysis of the thermal decomposition process was performed using the Doyle, Coats-Redfern, and Malek methods. The results suggested that the mechanisms of six stages were two-dimensional phase boundary mechanism, three-dimensional phase boundary mechanism, nucleation and nuclei growth mechanism (Avrami-Erofeev equation n = 3), two-dimensional phase boundary mechanism, three-dimensional diffusion mechanism (cylinder and G-B equation), and nucleation and nuclei growth mechanism (Avrami-Erofeev equation n = 1), respectively. The apparent active energies of six stages were 66.8 kJ × mol-1, 138.0 kJ × mol-1, 77.2 kJ × mol-1, 135.6 kJ × mol-1, 77.4 kJ × mol-1, and 92.2 kJ × mol-1, respectively. The frequency factors were 3.6 × 109 s-1, 8.8 × 1017 s-1, 4.6 × 109 s-1, 3.0 × 1014 s-1, 78.6 s-1, and 1.2 × 103 s-1, respectively.

  5. Thermal and mechanical properties of advanced impregnation materials for HTS cables and coils

    Science.gov (United States)

    Bagrets, N.; Otten, S.; Weiss, K.-P.; Kario, A.; Goldacker, W.

    2015-12-01

    In the growing field of high-temperature superconducting (HTS) applications, finding an appropriate impregnation material for cables and coils remains a challenging task. In HTS cables and coils, tapes have to be able to withstand mechanical loads during operation. Impregnation is playing a role as mechanical stabilization. However, material properties usually change significantly when going to low temperatures which can decrease performance of superconducting devices. For example, a large mismatch in thermal expansion between a conductor and impregnation material at low temperatures can lead to delamination and to degradation of the critical current. Impregnation materials can insulate tapes thermally which can lead to damage of the superconducting device in case of quench. Thus, thermal conductivity is an important property which is responsible for the temperature distribution in a superconducting cable or in a coil. Due to Lorentz forces acting on structural materials in a superconducting device, the mechanical properties of these materials should be investigated at operating temperatures of this device. Therefore, it is important to identify an advanced impregnation material meeting all specific requirements. In this paper, thermal and mechanical properties of impregnation material candidates with added fillers are presented in a temperature range from 300 K to 4 K.

  6. Measurements of mechanical thermal noise and energy dissipation in optical dielectric coatings

    CERN Document Server

    Li, Tianjun; Geitner, Mickael; Cagnoli, Gianpietro; Dolique, Vincent; Degallaix, Jérôme; Flaminio, Raffaele; Forest, Danièle; Granata, Massimo; Michel, Christophe; Morgado, Nazario; Pinard, Laurent; Bellon, Ludovic

    2014-01-01

    In recent years an increasing number of devices and experiments are shown to be limited by mechanical thermal noise. In particular sub-Hertz laser frequency stabilization and gravitational wave detectors, that are able to measure fluctuations of 1E-18 m/rtHz or less, are being limited by thermal noise in the dielectric coatings deposited on mirrors. In this paper we present a new measurement of thermal noise in low absorption dielectric coatings deposited on micro-cantilevers and we compare it with the results obtained from the mechanical loss measurements. For the first time the coating thermal noise is measured on a wide range of frequencies with high signal to noise ratio. In addition we present a novel technique to deduce the coating mechanical losses from the measurement of the mechanical quality factor which does not rely on the knowledge of the coating and substrate Young moduli. The dielectric coatings are deposited by ion beam sputtering. The results presented here give a frequency independent loss a...

  7. Effective thermal/mechanical properties of honeycomb core panels for hot structure applications

    NARCIS (Netherlands)

    Fatemi, J.; Lemmen, M.H.J.

    2009-01-01

    The present work addresses the computation of the effective thermal and mechanical properties of a honeycombcore sandwich panel. The panel considered has a hexagon-cell honeycomb core. An alternative method, based on the Gebhart factors within a hexagonal cell, is presented in addition to the

  8. Mechanical and thermal cycling effects on the flexural strength of glass ceramics fused to titanium

    NARCIS (Netherlands)

    Vasquez, Vanessa; Ozcan, Mutlu; Nishioka, Renato; Souza, Rodrigo; Mesquita, Alfredo; Pavanelli, Carlos

    2008-01-01

    This study evaluated the effects of mechanical and thermal cycling on the flexural strength (ISO 9693) of three brands of ceramics fused to commercially pure titanium (cpTi). Metallic frameworks of 25 x 3 x 0.5 mm dimensions (N = 84) were cast in cpTi, followed by 150-mu m aluminum oxide airborne pa

  9. Effective thermal/mechanical properties of honeycomb core panels for hot structure applications

    NARCIS (Netherlands)

    Fatemi, J.; Lemmen, M.H.J.

    2009-01-01

    The present work addresses the computation of the effective thermal and mechanical properties of a honeycombcore sandwich panel. The panel considered has a hexagon-cell honeycomb core. An alternative method, based on the Gebhart factors within a hexagonal cell, is presented in addition to the famili

  10. Composite Nonwovens Made of Cotton and Other Plant Fibers: Mechanical and Thermal Characterization

    Science.gov (United States)

    Composite nonwoven samples have been prepared from blends of fibers containing cotton and other fibers, such as bagasse, kenaf or ramie. The nonwoven structure has been stabilized with synthetic or bioderived polymers. Mechanical and thermal characteristics of nonwovens (tensile strength, modulus an...

  11. Mechanical and thermal cycling effects on the flexural strength of glass ceramics fused to titanium

    NARCIS (Netherlands)

    Vasquez, Vanessa; Ozcan, Mutlu; Nishioka, Renato; Souza, Rodrigo; Mesquita, Alfredo; Pavanelli, Carlos

    This study evaluated the effects of mechanical and thermal cycling on the flexural strength (ISO 9693) of three brands of ceramics fused to commercially pure titanium (cpTi). Metallic frameworks of 25 x 3 x 0.5 mm dimensions (N = 84) were cast in cpTi, followed by 150-mu m aluminum oxide airborne

  12. Preparation, Characterization, and Enhanced Thermal and Mechanical Properties of Epoxy-Titania Composites

    Science.gov (United States)

    Rubab, Zakya; Siddiqi, Humaira M.; Saeed, Shaukat

    2014-01-01

    This paper presents the synthesis and thermal and mechanical properties of epoxy-titania composites. First, submicron titania particles are prepared via surfactant-free sol-gel method using TiCl4 as precursor. These particles are subsequently used as inorganic fillers (or reinforcement) for thermally cured epoxy polymers. Epoxy-titania composites are prepared via mechanical mixing of titania particles with liquid epoxy resin and subsequently curing the mixture with an aliphatic diamine. The amount of titania particles integrated into epoxy matrix is varied between 2.5 and 10.0 wt.% to investigate the effect of sub-micron titania particles on thermal and mechanical properties of epoxy-titania composites. These composites are characterized by X-ray photoelectron (XPS) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric (TG), and mechanical analyses. It is found that sub-micron titania particles significantly enhance the glass transition temperature (>6.7%), thermal oxidative stability (>12.0%), tensile strength (>21.8%), and Young's modulus (>16.8%) of epoxy polymers. Epoxy-titania composites with 5.0 wt.% sub-micron titania particles perform best at elevated temperatures as well as under high stress. PMID:24578638

  13. Effect of electron beam irradiation on thermal and mechanical properties of aluminum based epoxy composites

    Science.gov (United States)

    Visakh, P. M.; Nazarenko, O. B.; Sarath Chandran, C.; Melnikova, T. V.; Nazarenko, S. Yu.; Kim, J.-C.

    2017-07-01

    The epoxy resins are widely used in nuclear and aerospace industries. The certain properties of epoxy resins as well as the resistance to radiation can be improved by the incorporation of different fillers. This study examines the effect of electron beam irradiation on the thermal and mechanical properties of the epoxy composites filled with aluminum nanoparticles at percentage of 0.35 wt%. The epoxy composites were exposed to the irradiation doses of 30, 100 and 300 kGy using electron beam generated by the linear electron accelerator ELU-4. The effects of the doses on thermal and mechanical properties of the aluminum based epoxy composites were investigated by the methods of thermal gravimetric analysis, tensile test, and dynamic mechanical analysis. The results revealed that the studied epoxy composites showed good radiation resistance. The thermal and mechanical properties of the aluminum based epoxy composites increased with increasing the irradiation dose up to 100 kGy and decreased with further increasing the dose.

  14. The simulation of mechanical and thermal behaviour of CANDU fuel channel in thermal transient conditions

    Energy Technology Data Exchange (ETDEWEB)

    Maria Mihalache; Vasile Radu; Margarit Pavelescu [INR-Pitesti (Romania)

    2006-07-01

    Full text of publication follows: In certain LOCA conditions in a CANDU-6 NPP (high temperature and high pressure), the pressure tube of fuel channel may balloon by creep into contact with the calandria tube. After the contact moment, a radial heat transfer to the moderator through the contact area is occurring. When the temperature of calandria tube walls increases, the contact area is drying and the heat transfer becomes inefficiently. Thus, the fuel channel could lose its integrity. This paper presents a computer code, DELOCA, developed in INR-Pitesti, which simulate the transient thermo-mechanical behaviour of CANDU fuel channel before and after contact. The code contains few models: alloy creep, heat transfer by conduction through the cylindrical walls, channel failure criteria and calculus of heat transfer at the calandria tube - moderator interface. This code evaluates the contact, dry-out and channel failure moments. In this paper, the simulation results calculated at different temperature increasing rates are presented. Also, the contact moments in different axial-circumferential segments for the postulated accident Rupture of Inlet Header of 5% (RIH5%) were presented. The simulations predict the strain and stress state in the circumferential-axial elements. The input data was furnished by the Cathena thermo-hydraulic code. Also, the results of RIH5% accident are presented in comparison with the results of same simulation with Cathena Code. (authors)

  15. Thermal and Mechanical Properties of Poly(butylene succinate Films Reinforced with Silica

    Directory of Open Access Journals (Sweden)

    Sangviroon Nanthaporn

    2015-01-01

    Full Text Available In recent year, bioplastics have become more popular resulting from the growing concerns on environmental issues and the rising fossil fuel price. However, their applications were limited by its mechanical and thermal properties. The aim of this research is thus to improve mechanical and thermal properties of PBS bioplastic films by reinforcing with silica. Due to the poor interfacial interaction between the PBS matrix and silica, glycidyl methacrylate grafted poly(butylene succinate (PBS-g-GMA was used as a compatibilizer in order to improve the interaction between bioplastic films and filler. PBS-g-GMA was prepared in a twin-screw extruder and analyzed by the FTIR spectrometer. PBS and silica were then mixed in a twin-screw extruder and processed into films by a chill-roll cast extruder. The effects of silica loading on thermal and mechanical properties of the prepared bioplastic films were investigated. It was found that the mechanical properties of PBS/silica composite films were improved when 1%wt of silica was added. However, the mechanical properties decreased with increasing silica loading due to the agglomeration of silica particles. The results also show that the silica/PBS films with PBS-g-GMA possessed improved mechanical properties over the films without the compatibilizer.

  16. Improvement and evaluation of thermal, electrical, sealing and mechanical contacts, and their interface materials

    Science.gov (United States)

    Luo, Xiangcheng

    Material contacts, including thermal, electrical, seating (fluid sealing and electromagnetic sealing) and mechanical (pressure) contacts, together with their interface materials, were, evaluated, and in some cases, improved beyond the state of the art. The evaluation involved the use of thermal, electrical and mechanical methods. For thermal contacts, this work evaluated and improved the heat transfer efficiency between two contacting components by developing various thermal interface pastes. Sodium silicate based thermal pastes (with boron nitride particles as the thermally conductive filler) as well as polyethylene glycol (PEG) based thermal pastes were developed and evaluated. The optimum volume fractions of BN in sodium silicate based pastes and PEG based pastes were 16% and 18% respectively. The contribution of Li+ ions to the thermal contact conductance in the PEG-based paste was confirmed. For electrical contacts, the relationship between the mechanical reliability and electrical reliability of solder/copper and silver-epoxy/copper joints was addressed. Mechanical pull-out testing was conducted on solder/copper and silver-epoxy/copper joints, while the contact electrical resistivity was measured. Cleansing of the copper surface was more effective for the reliability of silver-epoxy/copper joint than that of solder/copper joint. For sealing contacts, this work evaluated flexible graphite as an electromagnetic shielding gasket material. Flexible graphite was found to be at least comparable to conductive filled silicone (the state of the art) in terms of the shielding effectiveness. The conformability of flexible graphite with its mating metal surface under repeated compression was characterized by monitoring the contact electrical resistance, as the conformability is important to both electromagnetic scaling and fluid waling using flexible graphite. For mechanical contacts, this work focused on the correlation of the interface structure (such as elastic

  17. Unique Aeolian Transport Mechanisms on Mars: Respective Roles of Percussive and Repercussive Grain Populations in the Sediment Load

    Science.gov (United States)

    Marshall, John R.

    1999-01-01

    Experiments show that when sand-size grains impact a sediment surface with energy levels commensurate for Mars, small craters are formed by the ejection of several hundred grains from the bed. The experiments were conducted with a modified crossbow in which a sand-impelling sabot replaced the bolt-firing mechanism. Individual grains of sand could be fired at loose sand targets to observe ballistic effects unhindered by aerodynamic mobilization of the bed. Impact trajectories simulated the saltation process on dune surfaces. Impact craters were not elongated despite glancing (15 deg.) bed impact; the craters were very close to being circular. High-speed photography showed them to grow in both diameter and depth after the impactor had ricochetted from the crater site. The delayed response of the bed was "explosive" in nature, and created a miniature ejecta curtain spreading upward and outward for many centimeters for impact of 100-300 um-diameter grains into similar material. This behavior is explained by deposition of elastic energy in the bed by the "percussive" grain. Impact creates a subsurface stress regime or "quasi-Boussinesq" compression field. Elastic recovery of the bed occurs by dilatancy; shear stresses suddenly convert the grains to open packing and they consequently become forcefully ejected from the site. Random jostling of the grains causes radial homogenization of stress vectors and a resulting circular crater. A stress model based on repercussive bed dilatancy and interparticle adhesive forces (for smaller grains) predicts, to first order, the observed crater volumes for various impact conditions. On earth, only a few grains are mobilized by a percussive saltating grain; some grains are "knudged" along the ground, and some are partly expelled on short trajectories. These motions constitute reptation transport. On Mars, saltation and reptation become indistinct: secondary or "repercussive" trajectories have sufficient vertical impulse to create a

  18. 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

  19. Thermal-Mechanical Analysis of a Different Leadframe Thickness of Semiconductor Package under the Reflow Process

    Directory of Open Access Journals (Sweden)

    S. Abdullah

    2009-01-01

    Full Text Available The copper-based leadframe is practically proven effective in the thermal and reliability of a Quad Flat No Lead (QFN three dimension (3D stacked-die semiconductor package. Reducing the copper thickness is understood to present various thermal and reliability failure mode and mechanisms, such as die cracking and delamination. However, no in-depth study has been pursued in order to determine the capability of achieving the product requirements in terms of thermal and reliability in a 3D stacked-die package. The drive towards a Die-Free Package Cost (DFPC reduction has led the authors to study the used of a thin leadframe in a QFN 3D stacked-die. Hence, the work presents basis for the qualification of a thin leadframe design and also to demonstrate the thermal and reliability performance. Finally, an extensive virtual thermal-mechanical prototyping has to be achieved in order to understand the physics of materials during the assembly and reliability testing of a 3D stacked-die package with a thin leadframe. This design rule was found to be developed in order to prevent a die crack occurrence between die and leadframe in the semiconductor package.

  20. Thermo-mechanical test rig for experimental evaluation of thermal conductivity of ceramic pebble beds

    Energy Technology Data Exchange (ETDEWEB)

    Lo Frano, Rosa, E-mail: rosa.lofrano@ing.unipi.it; Aquaro, Donato; Pupeschi, Simone; Moscardini, Marigrazia

    2014-10-15

    Highlights: • Thermal conductivity values of bed as function of a material of known conductivity. • Minimizing the error caused by radial heat transfer. • Experimental evaluation of thermal conductivity of alumina pebble at different temperatures. • Experimental test with/without compression load. - Abstract: The experimental determination of mechanical and thermal properties of ceramic pebble beds, such as the lithium orthosilicate or lithium metatitanate, is a key issue in the framework of fusion power technology, for the reason that they are possible candidates in the design of breeder blankets. The paper deals with an experimental method for the evaluation of the thermal conductivity of ceramic pebble beds versus the temperature and compressive strain, based on a steady state heat flux through a material (alumina) of known conductivity. The alumina thermal conductivity is determined by means of the hot wire method. To assess the experimental method, a thermo-mechanical characterization of alumina pebble beds (a material largely available), having different diameters, considering a wide range of temperatures and compression forces has been carried out. Moreover preliminary tests have been performed on lithium orthosilicate and lithium metatitanate pebble beds.

  1. Improving environmental sustainability of concrete products: Investigation on MWC thermal and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Becchio, Cristina; Corgnati, Stefano Paolo; Kindinis, Andrea [Department of Energetics (DENER), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy); Pagliolico, Simonetta [Department of Materials Science and Engineering Chemistry (DISMIC), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (Italy)

    2009-11-15

    This research focuses on the possibility of constituting a more sustainable lightweight concrete, Mineralized Wood Concrete (MWC), substituting natural aggregates with wastes from woodworking activities. Exploiting this type of aggregates, a triple purpose has been achieved: preservation of natural raw materials, reuse of wastes and energy saving. Furthermore, the use of wood aggregates is a way to try to develop a sustainable concrete characterized by high thermal inertia, high thermal resistance and low weight. In this paper, effects of the addition of wood aggregates on mechanical and thermal properties of concrete are studied. Mechanical performances have been investigated with compressive strength tests, while a one-dimensional heat flow model has been used to predict the thermal conductivity of MWC. The use of MWC can be associated with the idea of a different typology of relatively heavy building envelope: this union could competitively answer to the demand of well-insulated building envelope and concurrently characterized by high thermal mass. From this union, a series of other values can be derived: low weight, environmentally friendly, easily industrialized and easy on-site casting. Consequently, applications of wood concrete in building constructions may be an interesting solution in order to improve sustainability and building energy efficiency. (author)

  2. A Silicon-Based Nanothin Film Solid Oxide Fuel Cell Array with Edge Reinforced Support for Enhanced Thermal Mechanical Stability.

    Science.gov (United States)

    Baek, Jong Dae; Yu, Chen-Chiang; Su, Pei-Chen

    2016-04-13

    A silicon-based micro-solid oxide fuel cell (μ-SOFC) with electrolyte membrane array embedded in a thin silicon supporting membrane, featuring a unique edge reinforcement structure, was demonstrated by utilizing simple silicon micromachining processes. The square silicon supporting membrane, fabricated by combining deep reactive ion etching and through-wafer wet etching processes, has thicker edges and corners than the center portion of the membrane, which effectively improved the mechanical stability of the entire fuel cell array during cell fabrication and cell operation. The 20 μm thick single crystalline silicon membrane supports a large number of 80 nm thick free-standing yttria-stabilized zirconia (YSZ) electrolytes. The fuel cell array was stably maintained at the open circuit voltage (OCV) of 1.04 V for more than 30 h of operation at 350 °C. A high peak power density of 317 mW/cm(2) was obtained at 400 °C. During a rigorous in situ thermal cycling between 150 and 400 °C at a fast cooling and heating rate of 25 °C/min, the OCV of the μ-SOFC recovered to its high value of 1.07 V without any drop caused by membrane failure, which justifies the superior thermal stability of this novel cell architecture.

  3. Architectural engineering of rod-coil compatibilizers for producing mechanically and thermally stable polymer solar cells.

    Science.gov (United States)

    Kim, Hyeong Jun; Kim, Jae-Han; Ryu, Ji-Ho; Kim, Youngkwon; Kang, Hyunbum; Lee, Won Bo; Kim, Taek-Soo; Kim, Bumjoon J

    2014-10-28

    While most high-efficiency polymer solar cells (PSCs) are made of bulk heterojunction (BHJ) blends of conjugated polymers and fullerene derivatives, they have a significant morphological instability issue against mechanical and thermal stress. Herein, we developed an architecturally engineered compatibilizer, poly(3-hexylthiophene)-graft-poly(2-vinylpyridine) (P3HT-g-P2VP), that effectively modifies the sharp interface of a BHJ layer composed of a P3HT donor and various fullerene acceptors, resulting in a dramatic enhancement of mechanical and thermal stabilities. We directly measured the mechanical properties of active layer thin films without a supporting substrate by floating a thin film on water, and the enhancement of mechanical stability without loss of the electronic functions of PSCs was successfully demonstrated. Supramolecular interactions between the P2VP of the P3HT-g-P2VP polymers and the fullerenes generated their universal use as compatibilizers regardless of the type of fullerene acceptors, including mono- and bis-adduct fullerenes, while maintaining their high device efficiency. Most importantly, the P3HT-g-P2VP copolymer had better compatibilizing efficiency than linear type P3HT-b-P2VP with much enhanced mechanical and thermal stabilities. The graft architecture promotes preferential segregation at the interface, resulting in broader interfacial width and lower interfacial tension as supported by molecular dynamics simulations.

  4. Mechanical and thermal properties of irradiated films based on Tilapia (Oreochromis niloticus) proteins

    Energy Technology Data Exchange (ETDEWEB)

    Sabato, S.F. [Radiation Technology Center, IPEN-CNEN/SP, Av. Lineu Prestes 2242, 05508 900 Sao Paulo, SP (Brazil)], E-mail: sfsabato@ipen.br; Nakamurakare, N.; Sobral, P.J.A. [Food Engineering Department, ZEA/FZEA/USP, Av. Duque de Caxias Norte 225, 13635 900 Pirassununga, SP (Brazil)

    2007-11-15

    Proteins are considered potential material in natural films as alternative to traditional packaging. When gamma radiation is applied to protein film forming solution it resulted in an improvement in mechanical properties of whey protein films. The objective of this work was the characterization of mechanical and thermal properties of irradiated films based on muscle proteins from Nile Tilapia (Oreochromis niloticus). The films were prepared according to a casting technique with two levels of plasticizer: 25% and 45% glycerol and irradiated in electron accelerator type Radiation Dynamics, 0.550 MeV at dose range from 0 to 200 kGy. Thermal properties and mechanical properties were determined using a differential scanning calorimeter and a texture analyzer, respectively. Radiation from electron beam caused a slightly increase on its tensile strength characteristic at 100 kGy, while elongation value at this dose had no reduction.

  5. Mechanical and Thermal Properties of Unsaturated Polyester/Vinyl Ester Blends Cured at Room Temperature

    Science.gov (United States)

    Ardhyananta, H.; Puspadewa, F. D.; Wicaksono, S. T.; Widyastuti; Wibisono, A. T.; Kurniawan, B. A.; Ismail, H.; Salsac, A. V.

    2017-05-01

    Unsaturated polyester (UP) resin containing aromatic ring was blended with vinyl ester (VE) at wide range composition (10, 20, 30, 40,and 80 wt.%) using mechanical blending method. The blends were cured at room temperature using methyl ethyl ketone peroxide (MEKP) (4 wt.%) as catalyst initiator without the presence of catalystaccelerator. The effect of vinyl ester composition on theenhancement of mechanical and thermal properties of unsaturated polyester/vinyl ester blends was investigated. The polymer blends were characterized by Fourier Transform Infra Red (FTIR)spectroscopy, tensile testing, hardness testing, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). IR spectra showed UP and VE peaks. The curing copolymerization reactionoccurred at vinyl (C=C) bonds. The addition of vinyl esters enhanced mechanical and thermal properties. The UP/VE blends showed homogeneous morphology, transparent and copolymer thermoset blend.

  6. The research Of Multilayer Thermal Insulation With Mechanical Properties Based On Model Analysis Test

    Science.gov (United States)

    Lianhua, Yin

    The heat shield of aircraft is made of the major thrusts structure with multilayer thermal insulation part. For protecting against thermo-radiation from larger thrusting force engine,the heat shield is installed around this engine nearby.The multilayer thermal insulation part with multilayer radiation/reflection structure is made of reflection layer and interval layer.At vacuum condition,these materials is higher heat insulation capability than other material,is applied for lots of pats on aircraft extensively.But because of these material is made of metal and nonmetal,it is impossible to receive it's mechanical properties of materials from mechanical tests.These paper describes a new measure of mechanical properties of materials in the heat shield based on model analysis test.At the requirement for the first order lateral frequency,these measure provide for the FEM analysis foundation on the optimization structure of the heat shield.

  7. The role of several heat transfer mechanisms on the enhancement of thermal conductivity in nanofluids

    Science.gov (United States)

    Machrafi, H.; Lebon, G.

    2016-09-01

    A modelling of the thermal conductivity of nanofluids based on extended irreversible thermodynamics is proposed with emphasis on the role of several coupled heat transfer mechanisms: liquid interfacial layering between nanoparticles and base fluid, particles agglomeration and Brownian motion. The relative importance of each specific mechanism on the enhancement of the effective thermal conductivity is examined. It is shown that the size of the nanoparticles and the liquid boundary layer around the particles play a determining role. For nanoparticles close to molecular range, the Brownian effect is important. At nanoparticles of the order of 1-100 nm, both agglomeration and liquid layering are influent. Agglomeration becomes the most important mechanism at nanoparticle sizes of the order of 100 nm and higher. The theoretical considerations are illustrated by three case studies: suspensions of alumina rigid spherical nanoparticles in water, ethylene glycol and a 50/50w% water/ethylene glycol mixture, respectively, good agreement with experimental data is observed.

  8. Mechanical and thermal properties of irradiated films based on Tilapia ( Oreochromis niloticus) proteins

    Science.gov (United States)

    Sabato, S. F.; Nakamurakare, N.; Sobral, P. J. A.

    2007-11-01

    Proteins are considered potential material in natural films as alternative to traditional packaging. When gamma radiation is applied to protein film forming solution it resulted in an improvement in mechanical properties of whey protein films. The objective of this work was the characterization of mechanical and thermal properties of irradiated films based on muscle proteins from Nile Tilapia ( Oreochromis niloticus). The films were prepared according to a casting technique with two levels of plasticizer: 25% and 45% glycerol and irradiated in electron accelerator type Radiation Dynamics, 0.550 MeV at dose range from 0 to 200 kGy. Thermal properties and mechanical properties were determined using a differential scanning calorimeter and a texture analyzer, respectively. Radiation from electron beam caused a slightly increase on its tensile strength characteristic at 100 kGy, while elongation value at this dose had no reduction.

  9. Experimental analysis on physical and mechanical properties of thermal shock damage of granite

    Directory of Open Access Journals (Sweden)

    He Xiao

    2017-01-01

    Full Text Available The purpose of this study was to explore the changes of mechanical and physical properties of granite under different thermal loading effects. Uniaxial compression experiments studying the rules of the influence of temperature load on mechanical properties of granite were carried out. After high-temperature heating at above 600 °C, granite tended to have stronger ductility and plasticity as well as declined peak stress and compressive strength. Thermogravimetry - differential scanning calorimetry (TG-DSC analysis results showed that, thermal load at different temperatures induced reactions such as water loss, oxidation and crystallization in the microstructure of granite, which led to physical changes of granite. Hence it is concluded that, heating can significantly weaken the mechanical performance of granite, which provides an important support for the optimization of heating assisted processing of granite. It also reveals that, heating assisted cutting technique can effectively lower energy consumption and improve processing efficiency.

  10. Thermal and mechanical properties of selected 3D printed thermoplastics in the cryogenic temperature regime

    Science.gov (United States)

    Weiss, K.-P.; Bagrets, N.; Lange, C.; Goldacker, W.; Wohlgemuth, J.

    2015-12-01

    Insulating materials for use in cryogenic boundary conditions are still limited to a proved selection as Polyamid, Glasfiber reinforced resins, PEEK, Vespel etc. These materials are usually formed to parts by mechanical machining or sometimes by cast methods. Shaping complex geometries in one piece is limited. Innovative 3D printing is now an upcoming revolutionary technology to construct functional parts from a couple of thermoplastic materials as ABS, Nylon and others which possess quite good mechanical stability and allow realizing very complex shapes with very subtle details. Even a wide range of material mixtures is an option and thermal treatments can be used to finish the material structure for higher performance. The use of such materials in cryogenic environment is very attractive but so far poor experience exists. In this paper, first investigations of the thermal conductivity, expansion and mechanical strength are presented for a few selected commercial 3D material samples to evaluate their application prospects in the cryogenic temperature regime.

  11. Mechanical, thermal and swelling properties of phosphorylated nanocellulose fibrils/PVA nanocomposite membranes.

    Science.gov (United States)

    Niazi, Muhammad Bilal Khan; Jahan, Zaib; Berg, Sigrun Sofie; Gregersen, Øyvind Weiby

    2017-12-01

    Cellulose nanofibrils (CNF) have strong reinforcing properties when incorporated in a compatible polymer matrix. This work reports the effect of the addition of phosphorylated nanocellulose (PCNF) on the mechanical, thermal and swelling properties of poly(vinyl alcohol) (PVA) nanocomposite membranes. The incorporation of nanocellulose in PVA reduced the crystallinity at 0%RH. However, when the films were exposed to higher humidities the crystallinity increased. No apparent trend is observed for mechanical properties for dry membranes (0% RH). However, at 93% RH the elastic modulus increased strongly from 0.12MPa to 0.82MPa when adding 6% PCNF. At higher humidities, the moisture uptake has large influence on storage modulus, tan δ and tensile properties. Membranes containing 1% PCNF absorbed most moisture. Swelling, thermal and mechanical properties indicate a good potential for applying of PVA/phosphorylated nanocellulose composite membranes for CO2 separation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Mechanical properties and microstructure of long term thermal aged WWER 440 RPV steel

    Science.gov (United States)

    Kolluri, M.; Kryukov, A.; Magielsen, A. J.; Hähner, P.; Petrosyan, V.; Sevikyan, G.; Szaraz, Z.

    2017-04-01

    The integrity assessment of the Reactor Pressure Vessel (RPV) is essential for the safe and Long Term Operation (LTO) of a Nuclear Power Plant (NPP). Hardening and embrittlement of RPV caused by neutron irradiation and thermal ageing are main reasons for mechanical properties degradation during the operation of an NPP. The thermal ageing-induced degradation of RPV steels becomes more significant with extended operational lives of NPPs. Consequently, the evaluation of thermal ageing effects is important for the structural integrity assessments required for the lifetime extension of NPPs. As a part of NRG's research programme on Structural Materials for safe-LTO of Light Water Reactor (LWR) RPVs, WWER-440 surveillance specimens, which have been thermal aged for 27 years (∼200,000 h) at 290 °C in a surveillance channel of Armenian-NPP, are investigated. Results from the mechanical and microstructural examination of these thermal aged specimens are presented in this article. The results indicate the absence of significant long term thermal ageing effect of 15Cr2MoV-A steel. No age hardening was detected in aged tensile specimens compared with the as-received condition. There is no difference between the impact properties of as-received and thermal aged weld metals. The upper shelf energy of the aged steel remains the same as for the as-received material at a rather high level of about 120 J. The T41 value did not change and was found to be about 10 °C. The microstructure of thermal aged weld, consisting carbides, carbonitrides and manganese-silicon inclusions, did not change significantly compared to as-received state. Grain-boundary segregation of phosphorus in long term aged weld is not significant either which has been confirmed by the absence of intergranular fracture increase in the weld. Negligible hardening and embrittlement observed after such long term thermal ageing is attributed to the optimum chemical composition of 15Cr2MoV-A for high thermal stability.

  13. Investigation of thermal aging damage mechanism of the Cast Duplex Stainless Steel

    Energy Technology Data Exchange (ETDEWEB)

    Wang Zhaoxi, E-mail: wangzx03@mails.tsinghua.edu.c [Applied Mechanics Laboratory, Tsinghua University, Beijing 100084 (China); Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); Xue Fei; Guo Wenhai [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); Shi Huiji [Applied Mechanics Laboratory, Tsinghua University, Beijing 100084 (China); Zhang Guodong [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); School of Mechanical and Power Engineering, Nanjing University of Technology, Nanjing 210009 (China); Shu Guogang [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China)

    2010-10-15

    Besides the macro-mechanical properties for thermal aging effect published in 'Thermal aging effect on Z3CN20.09M Cast Duplex Stainless Steel' (Nuclear Engineering and Design 239(2009) 2217-2223), the thermal aging damage mechanism is investigated in this paper through nano-indentation tests and micro-structures evolution examination. Numerical simulations were carried out with GTN continuum damage model to investigate the different crack propagation process for aging. The nano-indentation hardness values increase with aging time for both phases while the hardness values of the ferrite phase are much higher and increase much more. The nano-indentation energy indicating the toughness decreases for both phases with aging time. TEM results show that the Cr-enriched {alpha}' phase precipitates in the ferrite phase which is considered as the critical reason making the dislocation slip difficult and causing the increase of the strength and reduction of the toughness. The crack initiates from the ferrite phase instead of the austenite phase from the SEM observation and FEA simulation results, which reflects the change of the fracture mechanism for thermal aging.

  14. Coupled thermal-fluid-mechanics analysis of twin roll casting of A7075 aluminum alloy

    Science.gov (United States)

    Lee, Yun-Soo; Kim, Hyoung-Wook; Cho, Jae-Hyung; Chun, Se-Hwan

    2017-09-01

    Better understanding of temperature distribution and roll separation force during twin roll casting of aluminum alloys is critical to successfully fabricate good quality of aluminum strips. Therefore, the simulation techniques are widely applied to understand the twin roll casting process in a comprehensive way and to reduce the experimental time and cost of trial and error. However, most of the conventional approaches are considered thermally coupled flow, or thermally coupled mechanical behaviors. In this study, a fully coupled thermal-fluid-mechanical analysis of twin roll casting of A7075 aluminum strips was carried out using the finite element method. Temperature profile, liquid fraction and metal flow of aluminum strips with different thickness were predicted. Roll separation force and roll temperatures were experimentally obtained from a pilot-scale twin roll caster, and those results were compared with model predictions. Coupling the fluid of the liquid melt to the thermal and mechanical modeling reasonably predicted roll temperature distribution and roll separation force during twin roll casting.

  15. Thermal effect mechanism of magnetoresistance in p-type diamond films

    Institute of Scientific and Technical Information of China (English)

    Qin Guo-Ping; Kong Chun-Yang; Ruan Hai-Bo; Huang Gui-Juan; Cui Yu-Ting; Fang Liang

    2010-01-01

    Based on the analysis and the discussion of the influence of thermal ionization energy and various scatterings on magnetoresistance(MR) of p-type diamond films, a revised model of valence band split-off over temperature is put forward, and a corresponding calculation formula is given for the MR of p-type diamond films (Corbino discs). It is shown that the theoretical calculation that the MR of diamond films changes with temperature is consistent with the experiment. The influence of Fermi energy level on MR of diamond films is discussed. Additionally, the thermal effect mechanism of MR in p-type diamond films is also explored.

  16. Deformation due to mechanical and thermal sources in generalised orthorhombic thermoelastic material

    Indian Academy of Sciences (India)

    Rajneesh Kumar; Leena Rani

    2004-10-01

    A dynamical two-dimensional problem of thermoelasticity has been considered to investigate the disturbance due to mechanical (horizontal or vertical) and thermal source in a homogeneous, thermally conducting orthorhombic material. Laplace–Fourier transforms are applied to basic equations to form a vector matrix differential equation, which is then solved by eigenvalue approach. The displacements, stresses and temperature distribution so obtained in the physical domain are computed numerically and illustrated graphically. The numerical results of these quantities for zinc crystal-like material are illustrated to compare the results for different theories of generalised thermoelasticity for an insulated boundary and a temperature gradient boundary.

  17. Physicochemical, mechanical and thermal properties of chitosan films with and without sorbitol.

    Science.gov (United States)

    Liu, Mei; Zhou, Yibin; Zhang, Yang; Yu, Chen; Cao, Shengnan

    2014-09-01

    The effect of sorbitol on the physicochemical, mechanical and thermal properties of chitosan films with different degrees of deacetylation (DD; i.e., DD85% and DD95%) was investigated. The thickness, moisture content (MC), water solubility (WS) and water-vapor permeability (WVP) of the films were evaluated. Sorbitol addition reduced MC, increased WS and significantly (psorbitol increased the strain and decreased stress for both DD films, but DD95% could sustain higher strain and DD85% could sustain higher stress. Thermogravimetrics analysis and differential scanning calorimetry showed that sorbitol elicited a lower degradation temperature for both films, and that DD95% films exhibited higher thermal stability than DD85% films.

  18. A thermo-mechanical analysis of a particle impact during thermal spraying

    Science.gov (United States)

    Danouni, Samir; Abdellah El-hadj, Abdellah; Zirari, Mounir; Belharizi, Mohamed

    2016-05-01

    The present study discusses the development of a simulation model of transient impact between a particle and a substrate. The equations for structural behavior are coupled with those of heat transfer, wherein material properties are taken as temperature dependent. The set of equations is solved with Ansys program using a direct coupling method. At first, structural model is solved without heat transfer. Then, coupled thermo-mechanical model is solved with and without thermoelastic effects. Computational results indicate that thermal consideration has significant effects on contact problem. In addition, it is shown that, themoelasticity consideration is crucial for simulating these problems to determine the structural and thermal parameters.

  19. Synthesis, mechanical, thermal and chemical properties of polyurethanes based on cardanol

    Indian Academy of Sciences (India)

    C V Mythili; A Malar Retna; S Gopalakrishnan

    2004-06-01

    Cardanol, an excellent monomer for polymer production, has been isolated from CNSL and allowed to react with formaldehyde in a particular mole ratio in the presence of glutaric acid catalyst to give high-ortho novolac resin. Such characterized polyol has been condensed with diphenylmethane diisocyanate to produce rigid polyurethane. A commercially available polyol, polypropylene glycol-2000 (PPG-2000), has also been condensed with diphenylmethane diisocyanate and polyol to produce tough polyurethane. These polyurethanes were characterized with respect to their resistance to chemical reagents and mechanical properties such as tensile strength, percentage elongation, tear strength and hardness. Differential thermal analysis (DTA) and thermo-gravimetric analysis (TGA) were undertaken for thermal characterization.

  20. Morphology, Mechanical and Thermal Properties of PBT-TiO2 Polymer Nanocomposite

    OpenAIRE

    Metanawin Tanapak; Jamjumrus Anusorn; Metanawin Siripan

    2015-01-01

    This research aims to study the effects of the TiO2 in PBT composite fibers on the thermal properties, mechanical properties and photocatalytic properties of the polymer composite. The results showed that the tensile strength of the TiO2/PBT fibers decreased with increasing in the content of TiO2 in polymer matrix. The content of TiO2 in composite fibers did not affect the thermal properties of the fibers but the %crystalline of the composite fibers were increased with content of TiO2 in the ...

  1. Life prediction of thermal-mechanical fatigue using strain-range partitioning

    Science.gov (United States)

    Halford, G. R.; Manson, S. S.

    1975-01-01

    The applicability is described of the method of Strainrange Partitioning to the life prediction of thermal-mechanical strain-cycling fatigue. An in-phase test on 316 stainless steel is analyzed as an illustrative example. The observed life is in excellent agreement with the life predicted by the method using the recently proposed Step-Stress Method of experimental partitioning, the Interation Damage Rule, and the life relationships determined at an isothermal temperature of 705 C. Implications of the study are discussed relative to the general thermal fatigue problem.

  2. Mechanical and Thermal Characterisation of a TT Half-Module Prototype

    CERN Document Server

    Lehner, F; Pangilinan, M; Siegler, M

    2005-01-01

    This note describes the mechanical effects of thermal cycles on a TT half-module, to demonstrate that the detectors can withstand the expected thermal gradients without damage. The stress transferred by the carbon fiber rails and the ceramic to the silicon sensors was investigated, and the deformation that occurred during these tests was measured by strain gauges that were attached to sensors on a test half-module. In addition, heat transfer through the carbon fiber rails was studied. Furthermore, we present a comparison of different materials proposed to build the carbon fiber rails of the modules.

  3. Impact and dynamic mechanical thermal properties of textile silk reinforced epoxy resin composites

    Science.gov (United States)

    Yang, K.; Guan, J.

    2016-07-01

    Silk fabric reinforced epoxy resin composites (SFRPs) were prepared using simple techniques of hand lay-up, hot-press and vacuum treatment, and a series of volume fractions of silk reinforcements were achieved. The impact properties and dynamic mechanical properties of SFRPs were investigated using a pendulum impact testing method and dynamic mechanical thermal analysis (DMTA). The results suggest that silk reinforcement could greatly enhance the mechanical performances of SFRPs. The impact strength reached a maximum of 71 kJ/m2 for 60%-silk SFRP, which demonstrated a potential of silk composites for defence and impact- resistant materials.

  4. Thermal and mechanical effect during rapid heating of astroloy for improving structural integrity

    Energy Technology Data Exchange (ETDEWEB)

    Popoolaa, A.P.I., E-mail: popoolaapi@tut.ac.za [Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Oluwasegun, K.M. [Department of Materials Science and Engineering, Obafemi Awolowo University (Nigeria); Olorunniwo, O.E., E-mail: segun_nniwo@yahoo.com [Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Materials Science and Engineering, Obafemi Awolowo University (Nigeria); Atanda, P.O. [Department of Materials Science and Engineering, Obafemi Awolowo University (Nigeria); Aigbodion, V.S. [Department of Chemical, Metallurgical and Materials Engineering, Tshwane University of Technology, Pretoria (South Africa); Department of Metallurgical and Materials Engineering, University of Nigeria, Nsukka (Nigeria)

    2016-05-05

    The behaviour of γ′ phase to thermal and mechanical effects during rapid heating of Astroloy(Turbine Disc alloy) a Powder metallurgy (PM) nickel base superalloy has been investigated. The thermo-mechanical affected zone (TMAZ) and heat affected zone (HAZ) microstructure of an inertia friction welded Astroloy were simulated using a Gleeble thermo-mechanical simulation system. Detailed microstructural examination of the simulated TMAZ and HAZ and those present in actual inertial friction welded specimens showed that γ′ particles persisted during rapid heating up to a temperature where the formation of liquid is thermodynamically favoured, and subsequently re-solidified eutectically. The result obtained showed that forging during the thermo-mechanical simulation significantly enhanced resistance to weld liquation cracking of the alloy. This is attributable to strain-induced rapid isothermal dissolution of the constitutional liquation products within 150 μm from the centre of the forged sample. This was not observed in purely thermally simulated samples. The microstructure within the TMAZ of the as-welded alloy is similar to the microstructure in the forged Gleeble specimens. - Highlights: • The behaviour of γ′ phase to thermal and mechanical effects during rapid heating of Astrology • The thermo-mechanical affected zone (TMAZ) and heat affected zone (HAZ). • significantly enhanced resistance to weld liquation cracking of the alloy. • This was not observed in purely thermally simulated samples. • The microstructure within the TMAZ of the as-welded alloy is similar to the microstructure in the forged Gleeble specimens.

  5. Effect of resin infiltration on the thermal and mechanical properties of nano-sized silica-based thermal insulation.

    Science.gov (United States)

    Lee, Jae Chun; Kim, Yun-Il; Lee, Dong-Hun; Kim, Won-Jun; Park, Sung; Lee, Dong Bok

    2011-08-01

    Several kinds of nano-sized silica-based thermal insulation were prepared by dry processing of mixtures consisting of fumed silica, ceramic fiber, and a SiC opacifier. Infiltration of phenolic resin solution into the insulation, followed by hot-pressing, was attempted to improve the mechanical strength of the insulation. More than 22% resin content was necessary to increase the strength of the insulation by a factor of two or more. The structural integrity of the resin-infiltrated samples could be maintained, even after resin burn-out, presumably due to reinforcement from ceramic fibers. For all temperature ranges and similar sample bulk density values, the thermal conductivities of the samples after resin burn-out were consistently higher than those of the samples obtained from the dry process. Mercury intrusion curves indicated that the median size of the nanopores formed by primary silica aggregates in the samples after resin burn-out is consistently larger than that of the sample without resin infiltration.

  6. Thermal Fluid-Solid Interaction Model and Experimental Validation for Hydrostatic Mechanical Face Seals

    Institute of Scientific and Technical Information of China (English)

    HUANG Weifeng; LIAO Chuanjun; LIU Xiangfeng; SUO Shuangfu; LIU Ying; WANG Yuming

    2014-01-01

    Hydrostatic mechanical face seals for reactor coolant pumps are very important for the safety and reliability of pressurized-water reactor power plants. More accurate models on the operating mechanism of the seals are needed to help improve their performance. The thermal fluid-solid interaction (TFSI) mechanism of the hydrostatic seal is investigated in this study. Numerical models of the flow field and seal assembly are developed. Based on the mechanism for the continuity condition of the physical quantities at the fluid-solid interface, an on-line numerical TFSI model for the hydrostatic mechanical seal is proposed using an iterative coupling method. Dynamic mesh technology is adopted to adapt to the changing boundary shape. Experiments were performed on a test rig using a full-size test seal to obtain the leakage rate as a function of the differential pressure. The effectiveness and accuracy of the TFSI model were verified by comparing the simulation results and experimental data. Using the TFSI model, the behavior of the seal is presented, including mechanical and thermal deformation, and the temperature field. The influences of the rotating speed and differential pressure of the sealing device on the temperature field, which occur widely in the actual use of the seal, are studied. This research proposes an on-line and assembly-based TFSI model for hydrostatic mechanical face seals, and the model is validated by full-sized experiments.

  7. V-groove-based compact FBG package for thermal tuning and mechanical stability

    Science.gov (United States)

    Zhang, Li; Fang, Wei; Wang, Di; Chen, Di-Jun; Cai, Hai-Wen; Qu, Rong-Hui

    2016-04-01

    We demonstrated a V-groove-based fiber Bragg grating (FBG) package that has been glue-filled and cured to make it a bulky component with much improved mechanical stability. The V-groove can be executed with many types of materials including plastics, ceramics, semiconductors, and metals, providing an easy method for redesigning the thermal tuning performance of FBGs by selecting among a wide variety of materials and processes. We achieved more than 10-nm thermal wavelength tuning and thermal sensitivity ranging from 15 to 160 pm/K. The original FBG spectrum can be maintained without any degradation because the fiber is buried in the V-groove. The compact package does not increase the original grating length and turns the FBG into a planar waveguide grating, improving FBG applications in telecommunications, external cavity lasers, and sensing areas.

  8. Effect of high thermal expansion glass infiltration on mechanical properties of alumina–zirconia composite

    Indian Academy of Sciences (India)

    A Balakrishnan; B B Panigrahi; K P Sanosh; Min-Cheol Chu; T N Kim; Seong-Jai Cho

    2009-08-01

    This work studies the effect on the mechanical properties of alumina-10 wt% zirconia (3 mol% yttria stabilized) composite by infiltrating glass of a higher thermal expansion (soda lime glass) on the surface at high temperature. The glass improved the strength of composite at room temperature as well as at high temperature. This could be attributed to the drastic drop in the coefficient of thermal expansion due to the compositional change in the soda lime glass during infiltration. There was a significant improvement in the Weibull modulus after glass infiltration. Glass infiltrated samples showed better thermal shock resistance. The magnitude of strength increment was found to be in the order of the surface residual stress generated by thermo-elastic properties mismatch between the composite and the penetrated glass.

  9. The effect of surface roughness on thermal-elasto-hydrodynamic model of contact mechanical seals

    Science.gov (United States)

    Wen, QingFeng; Liu, Ying; Huang, WeiFeng; Suo, ShuangFu; Wang, YuMing

    2013-10-01

    In this paper, the effect of surface roughness on sealing clearance, pressure distribution, friction torque and leakage is studied by the thermal-elasto-hydrodynamic mixed lubrication model. A convergent nominal clearance is formed by the pressure deformation and thermal deformation of the seal faces. This causes more serious wear in the inner side than that of the outer side of the contact area. Mass leakage increases with the growing of the surface roughness. The temperature and thermal deformation on the seal surface increases substantially if the roughness is reduced. The contact mechanical seals have consistent performance when the standard deviation of surface roughness is approximately 0.2 μm. In order to validate the theoretical analysis model, a method combining the measurement of three-dimensioned profile and Raman spectrum is proposed.

  10. Qualitative Experimental Evidences for the thermal Wave Mechanisms of temperature Oscillations in Living Tissues

    Institute of Scientific and Technical Information of China (English)

    JingLiu; XingguoSun; 等

    1996-01-01

    To make it possible for the thermal wave theory on temperature oscillation (TO)effects in living tissues to be founded on the substantial experimental basis,a series of typical decisive experiments in vivo as well as in artificially simulating costructions were carred out.COnclusions obtained including some other scholars animal experimental results all greatly support the thermal wave viewpoint qualitatively,A few experimental facts used not to be easily understood from the classical viewpoint are also well reinterpreted.The revealing on the thermal wave mechanisms of TO in living tissues is a brand new discovery and deep insight into this important thermophysiological phenomenon,It may possibly promote new investigations on the corresponding topics in the field of bioheat transfer science.

  11. Mechanical and thermal properties of denture PMMA reinforced with silanized aluminum borate whiskers.

    Science.gov (United States)

    Zhang, Xinjing; Zhang, Xiuyin; Zhu, Bangshang; Lin, Kaili; Chang, Jiang

    2012-01-01

    The aim of this study was to investigate the mechanical and thermal properties of denture polymethyl methacrylate (PMMA) reinforced with aluminum borate whiskers (ABWs). To improve bonding between ABWs and PMMA matrix, the surface of ABWs was modified with a silane coupling agent. Varied contents of silanized ABWs -ranging between 1 and 20 wt%- were mixed into the PMMA resin matrix to prepare ABW/PMMA composites, which were subjected to three-point bending test, Vickers hardness test, and thermal analysis. Silanized ABWs improved the flexural strength, surface hardness, and thermal stability of PMMA. Optimal amount of ABWs in the PMMA matrix was 5 wt%, which provided the ABW/PMMA with maximum reinforcement.

  12. Mechanism for thermal relic dark matter of strongly interacting massive particles.

    Science.gov (United States)

    Hochberg, Yonit; Kuflik, Eric; Volansky, Tomer; Wacker, Jay G

    2014-10-24

    We present a new paradigm for achieving thermal relic dark matter. The mechanism arises when a nearly secluded dark sector is thermalized with the standard model after reheating. The freeze-out process is a number-changing 3→2 annihilation of strongly interacting massive particles (SIMPs) in the dark sector, and points to sub-GeV dark matter. The couplings to the visible sector, necessary for maintaining thermal equilibrium with the standard model, imply measurable signals that will allow coverage of a significant part of the parameter space with future indirect- and direct-detection experiments and via direct production of dark matter at colliders. Moreover, 3→2 annihilations typically predict sizable 2→2 self-interactions which naturally address the "core versus cusp" and "too-big-to-fail" small-scale structure formation problems.

  13. Effects of Thermal Treatment on the Dynamic Mechanical Properties of Coal Measures Sandstone

    Science.gov (United States)

    Li, Ming; Mao, Xianbiao; Cao, Lili; Pu, Hai; Mao, Rongrong; Lu, Aihong

    2016-09-01

    Many projects such as the underground gasification of coal seams and coal-bed methane mining (exploitation) widely involve the dynamic problems of coal measures sandstone achieved via thermal treatment. This study examines the dynamic mechanical properties of coal measures sandstone after thermal treatment by means of an MTS653 high-temperature furnace and Split Hopkinson pressure bar test system. Experimental results indicate that 500 °C is a transition point for the dynamic mechanical parameters of coal measures sandstone. The dynamic elastic modulus and peak strength increase linearly from 25 to 500 °C while the dynamic peak strain decreases linearly over the same temperature range. The dynamic elastic modulus and peak strength drop quickly from 500 to 800 °C, with a significant increase in the dynamic peak strain over the same temperature range. The rock mechanics are closely linked to material composition and mesoscopic structure. Analysis by X-ray diffraction and scanning electron microscopy indicate that the molecules inside the sandstone increase in density due to the thermal expansion of the material particles, which effectively improves the deformation resistance and carrying capacity of the sandstone and reduces the likelihood of axial deformation. With heat treatment that exceeds 500 °C, the dynamic mechanical properties rapidly weaken due to the decomposition of kaolinite; additionally, hot cracking of the mineral particles within the materials arises from coal sandstone internal porosity, and other defects gradually appear.

  14. Effect of acoustic softening on the thermal-mechanical process of ultrasonic welding.

    Science.gov (United States)

    Chen, Kunkun; Zhang, Yansong; Wang, Hongze

    2017-03-01

    Application of ultrasonic energy can reduce the static stress necessary for plastic deformation of metallic materials to reduce forming load and energy, namely acoustic softening effect (ASE). Ultrasonic welding (USW) is a rapid joining process utilizing ultrasonic energy to form a solid state joint between two or more pieces of metals. Quantitative characterization of ASE and its influence on specimen deformation and heat generation is essential to clarify the thermal-mechanical process of ultrasonic welding. In the present work, experiments were set up to found out mechanical behavior of copper and aluminum under combined effect of compression force and ultrasonic energy. Constitutive model was proposed and numerical implemented in finite element model of ultrasonic welding. Thermal-mechanical analysis was put forward to explore the effect of ultrasonic energy on the welding process quantitatively. Conclusions can be drawn that ASE increases structural deformation significantly, which is beneficial for joint formation. Meanwhile, heat generation from both frictional work and plastic deformation is slightly influenced by ASE. Based on the proposed model, relationship between ultrasonic energy and thermal-mechanical behavior of structure during ultrasonic welding was constructed.

  15. Study of the effect of gamma irradiation on a commercial polycyclooctene I. Thermal and mechanical properties

    Science.gov (United States)

    García-Huete, N.; Laza, J. M.; Cuevas, J. M.; Vilas, J. L.; Bilbao, E.; León, L. M.

    2014-09-01

    A gamma radiation process for modification of commercial polymers is a widely applied technique to promote new physical, chemical and mechanical properties. Gamma irradiation originates free radicals able to induce chain scission or recombination of radicals, which induces annihilation, branching or crosslinking processes. The aim of this work is to research the structural, thermal and mechanical changes induced on a commercial polycyclooctene (PCO) when it is irradiated with a gamma source of 60Co at different doses (25-200 kGy). After gamma irradiation, gel content was determined by Soxhlet extraction in cyclohexane. Furthermore, thermal properties were evaluated before and after Soxhlet extraction by means of Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC), as well as mechanical properties were measured by Dynamic Mechanical Thermal Analysis (DMTA). The results showed the variations of the properties depending on the irradiation dose. Finally, a first approach to evaluate qualitatively the shape memory behaviour of all irradiated PCO samples was performed by a visually monitoring shape recovery process.

  16. Preparation and thermal-mechanical characterization of nanoclay-unsaturated polyester composites.

    Science.gov (United States)

    Calvo, S; Prolongo, M G; Salom, C; Masegosa, R M

    2010-04-01

    Recently polymer nanocomposites have attracted great interest as much as in industry as in research laboratories, due to they often show remarkable improvement in their mechanical and thermal properties when are compared with the virgin polymers. Among nanocomposites, nanoclay-reinforced polymers have been widely studied, specifically, those formed by a thermosetting polymer matrix, like unsaturated polyester crosslinked resin reinforced with layered silicates, like montmorillonite. In this work we have prepared nanocomposites formed by an isophtalic unsaturated polyester crosslinked resin (UP) reinforced with different contents (2-10 wt%) of organic modified montmorillonite (OMMT). The UP/OMMT nanocomposites have been prepared following different procedures and the structural characterization has been carried out by using X-ray diffraction (XRD). In all the cases an increase of the d-spacing between layers of the OMMT has been detected. The objective of this study is to analyze the thermal and mechanical behaviour of nanocomposites. For all of the reinforced systems, the glass transition temperatures values, Tg, obtained by differential scanning calorimetry (DSC) and dynamic-mechanical thermal analysis, (DMTA) are higher than the corresponding ones to neat UP. On the other hand, the OMMTP mechanical behaviour has been evaluated by DMTA and by tensile tests. Both techniques reveal an increase in Young modulus, however, a decrease of the tensile strength is observed in all the reinforced systems.

  17. Mechanical and thermal characterisation of poly (l-lactide) composites reinforced with hemp fibres

    Science.gov (United States)

    Shakoor, A.; Muhammad, R.; Thomas, N. L.; Silberschmidt, V. V.

    2013-07-01

    Polylactic acid (PLA) is the most promising in the bio-derived polymer's family. But its use can be constrained by its poor mechanical properties, poor thermal stability and processing difficulties. The objective of this research is to investigate and improve mechanical and dynamic thermal properties of PLA by developing PLA composites reinforced with natural fibres (hemp). Composites were prepared by melt blending of PLA with hemp fibres. Their properties were investigated using mechanical and dynamic thermal analysis. The elastic modulus increased significantly - from 4.1 ± 0.74 to 9.32 ± 0.86 (GPA) - when the weight fraction of hemp increased from 0 to 30(wt %). The storage modulus obtained by dynamic mechanical analysis increased from 2.20 to 4.58 (GPA) for the same change in the volume fraction of hemp. FE simulation of tensile testing and DMA were carried out to investigate the effect of strain rate and temperature on the observed properties respectively. The model was developed in the commercially available code MSC Marc mentate. The model validated all experimental results.

  18. 3D Thermal and Mechanical Analysis of a Single Event Burnout

    Science.gov (United States)

    Peretti, Gabriela; Demarco, Gustavo; Romero, Eduardo; Tais, Carlos

    2015-08-01

    This paper presents a study related to thermal and mechanical behavior of power DMOS transistors during a Single Event Burnout (SEB) process. We use a cylindrical heat generation region for emulating the thermal and mechanical phenomena related to the SEB. In this way, it is avoided the complexity of the mathematical treatment of the ion-device interaction. This work considers locating the heat generation region in positions that are more realistic than the ones used in previous work. For performing the study, we formulate and validate a new 3D model for the transistor that maintains the computational cost at reasonable level. The resulting mathematical models are solved by means of the Finite Element Method. The simulations results show that the failure dynamics is dominated by the mechanical stress in the metal layer. Additionally, the time to failure depends on the heat source position, for a given power and dimension of the generation region. The results suggest that 3D modeling should be considered for a detailed study of thermal and mechanical effects induced by SEBs.

  19. Vulcanization Kinetics and Mechanical Properties of Ethylene Propylene Diene Monomer Thermal Insulation

    Directory of Open Access Journals (Sweden)

    Mohamad Irfan Fathurrohman

    2015-07-01

    Full Text Available The vulcanization kinetics of Ethylene-propylene diene monomer (EPDM rubber thermal insulation was studied by using rheometer under isothermal condition at different temperatures. The rheometry analysis was used to determining the cure kinetic parameters and predicting the cure time of EPDM thermal insulation. The experimental results revealed that the curing curves of EPDM thermal insulation were marching and the optimum curing time decreased with increasing the temperature. The kinetic parameters were determined from the autocatalytic model showed close fitting with the experimental results, indicating suitability of autocatalytic model in characterizing the cure kinetics. The activation energy was determined from the autocatalytic model is 46.3661 kJ mol-1. The cure time were predicted from autocatalytic model and the obtained kinetic parameter by using the relationship among degree of conversion, cure temperature, and cure time. The predictions of cure time provide information for the actual curing characteristic of EPDM thermal insulation. The mechanical properties of EPDM thermal insulation with different vulcanization temperatures showed the same hardness, tensile strength and modulus at 300%, except at temperature 70 °C, while the elongation at breaking point decreased with increasing temperature of vulcanization. © 2015 BCREC UNDIP. All rights reservedReceived: 8th April 2014; Revised: 7th January 2015; Accepted: 16th January 2015How to Cite: Fathurrohman, M.I., Maspanger, D.R., Sutrisno, S. (2015. Vulcanization Kinetics and Mechanical Properties of Ethylene Propylene Diene Monomer Thermal Insulation. Bulletin of Chemi-cal Reaction Engineering & Catalysis, 10 (2, 104-110. (doi:10.9767/bcrec.10.2.6682.104-110Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.6682.104-110 

  20. Medulla Oblongata Mechanism of Inhibitory Effect of Thermal Stimulation to Nociceptive Colorectal Distention in Rats

    Institute of Scientific and Technical Information of China (English)

    Liang Li; Pei-Jing Rong; Xin-Yan Gao; Hui Ben; Hong Cai; Bing Zhu

    2016-01-01

    Objective: To discuss mechanism of moxibustion (thermal stimulation) effect and best moxibustion stimulus parameter. Methods: Experiments were performed on 48 male Sprague-Dawley rats. Unit discharges from individual single neuron were recorded extracellularly with glass-microelectrode in Subnucleus Reticularis Dorsalis (SRD). Visceral-intrusive stimulation is done by colorectal distension. Thermal stimulation with different temperature (40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C) and different stimulus area (diameter of circle:1.0 cm, 1.5 cm, 2.0 cm, 2.5 cm, 3.0 cm, 3.5 cm, 4.0cm) was applied around RN12 during nociceptive colorectal distension. Results: SRD neurons could be activated by visceral stimulation within noxious range. Under low temperature of stimulus, especially under 45°C of pain threshold to ordinary people, visceral nociceptive afferent facilitated thermal stimulus from the body surface. While after thermal stimulation reached a harmful degree, the thermal stimulus will inhibit visceral nociceptive afferent. Moreover, statistics show that the higher the temperature is, the smaller the size of stimulation area is needed, and they correlate with each other negatively. Conclusion: Visceral nociception could be inhibited by somatic thermal stimulation with specific parameter at medulla level. According to our finding, best thermal stimulation temperature is around 48°C and the best size of stimulation area is around 3.14-7.07cm2 (with 2.0-3.0cm diameter).

  1. Effects of Thermal Damage and Confining Pressure on the Mechanical Properties of Coarse Marble

    Science.gov (United States)

    Yao, Mengdi; Rong, Guan; Zhou, Chuangbing; Peng, Jun

    2016-06-01

    Heating treatment generally causes thermal damage inside rocks, and the influence of thermal damage on mechanical properties of rocks is an important topic in rock mechanics. The coarse marble specimens drilled out from a rock block were first heated to a specific temperature level of 200, 400 and 600 °C except the control group left at 20 °C. A series of triaxial compression tests subjected to the confining pressure of 0, 5, 10, 15, 20, 25, 30, 35 and 40 MPa were conducted. Coupling effects of thermal damage and confining pressure on the mechanical properties of marbles including post-peak behaviors and failure modes, strength and deformation parameters, characteristic stresses in the progressive failure process had been investigated. Meanwhile, accompanied tests of physical properties were carried out to study the effect of thermal damage on microstructure, porosity and P-wave velocity. Finally, the degradation parameter was defined and a strength-degradation model to describe the peak strength was proposed. Physical investigations show that porosity increases slowly and P-wave velocity reduces dramatically, which could be re-demonstrated by the microscopy results. As for the post-peak behaviors and the failure modes, there is a brittle to ductile transition trend with increasing confining pressure and thermal effect reinforces the ductility to some degree. The comparative study on strength and deformation parameters concludes that heating causes damage and confining pressure inhibits the damage to develop. Furthermore, crack damage stress and crack initiation stress increase, while the ratios of crack damage stress to peak strength and crack initiation stress to peak strength show a decreasing trend with the increase of confining pressure; the magnitude of crack damage stress or crack initiation stress shows a tendency of decrease with the increasing heating temperature and the tendency vanishes subjected to high confinement.

  2. Thermal decomposition mechanism of p-tert-butyl-calix[n]arenes

    Energy Technology Data Exchange (ETDEWEB)

    Chennakesavulu, K., E-mail: chennanml@yahoo.com [National Metallurgical Laboratory Madras Centre, CSIR Madras Complex, Taramani, Chennai 600 113 (India); Department of Chemistry, Sathyabama University, Jeppiaar Nagar, Chennai 600 119 (India); Sreedevi, P.; Raviathul Basaria, M. [National Metallurgical Laboratory Madras Centre, CSIR Madras Complex, Taramani, Chennai 600 113 (India); Ramanjaneya Reddy, G. [Department of Inorganic Chemistry, Guindy Campus, University of Madras, Chennai 600 025 (India); Sasipraba, T. [International Research Centre, Sathyabama University, Jeppiaar Nagar, Chennai 600 119 (India); Bhaskar Raju, G.; Prabhakar, S. [National Metallurgical Laboratory Madras Centre, CSIR Madras Complex, Taramani, Chennai 600 113 (India)

    2014-01-10

    Highlights: • Systematic thermal decomposition, structural elucidation of intermediates at various quenched temperatures. • At solid state the phenolic free radical was quenched and was evidenced by recording stable EPR. • Since the lower decomposition energy these p-tert-butyl-calix[n]arenes can be used as a antioxidants for thermal stabilization of polyolefins. • Solid state NMR CP-MAS studies show the breakage of calixarene at bridged methylene. • Kinetic triplets of p-tert-butyl-calixarenes were determined by model free methods. - Abstract: Thermal decomposition of p-tert-butyl-calix[n]arene was studied using thermo gravimetry (TG) and differential thermo gram (DTG) methods. Non-isothermal TG was done under static air atmosphere with 1, 2.5, 5.0 and 10.0 K/min. Model-free methods such as Friedman and Flynn Wall Ozawa (FWO) were used to evaluate the kinetic parameters such as activation energy and exponential factors. The probable thermal decomposition mechanism was proposed by analyzing the quenched intermediate p-tert-butyl-calix[n]arene samples with FTIR, mass, {sup 1}H NMR, {sup 13}C NMR cross polarization magic angle spectrometry (CP-MAS), EPR spectroscopy and elemental analysis. The thermal stability of the polyolefins was checked with p-tert-butyl-calix[n]arene as an antioxidant additive.

  3. Reinforced Flax Mat/Modified Polylactide (PLA) Composites: Impact, Thermal, and Mechanical Properties

    Science.gov (United States)

    Siengchin, S.

    2014-05-01

    Polylactide (PLA)/flax mat and modified PLA/flax mat composites were produced by the hot pressing technique. The dispersion of the flax mat in the composites was studied by the scanning electron microscopy (SEM). The PLA composites were subjected to an instrumented falling-weight impact test. The mechanical and thermal properties of the composites were determined by using tensile tests, a thermogravimetric analysis (TGA), and a dynamic-mechanical thermal analysis (DMTA). It was found that the flat mat increased the impact resistance of PLA, but the tensile strength of the modified PLA/flax mat composite decreased slightly compared with that of PLA. Data on the elongation at break pointed to a higher ductility of the modified PLA and its composites. Moreover, the addition of a thermal modifier enhanced the thermal resistance below the processing temperature of PLA and had a marginal effect on its glass-transition temperature. The master curves of the storage modulus were constructed by employing the time-temperature superposition (TTS) principle. The principle of a linear viscoelastic material was fairly applicable to transition from the modulus to the creep compliance for all the systems studied.

  4. Assessment of structural, thermal, and mechanical properties of portlandite through molecular dynamics simulations

    Science.gov (United States)

    Hajilar, Shahin; Shafei, Behrouz

    2016-12-01

    The structural, thermal, and mechanical properties of portlandite, the primary solid phase of ordinary hydrated cement paste, are investigated using the molecular dynamics method. To understand the effects of temperature on the structural properties of portlandite, the coefficients of thermal expansion of portlandite are determined in the current study and validated with what reported from the experimental tests. The atomic structure of portlandite equilibrated at various temperatures is then subjected to uniaxial tensile strains in the three orthogonal directions and the stress-strain curves are developed. Based on the obtained results, the effect of the direction of straining on the mechanical properties of portlandite is investigated in detail. Structural damage analysis is performed to reveal the failure mechanisms in different directions. The energies of the fractured surfaces are calculated in different directions and compared to those of the ideal surfaces available in the literature. The key mechanical properties, including tensile strength, Young's modulus, and fracture strain, are extracted from the stress-strain curves. The sensitivity of the obtained mechanical properties to temperature and strain rate is then explored in a systematic way. This leads to valuable information on how the structural and mechanical properties of portlandite are affected under various exposure conditions and loading rates.

  5. Automated thermal treatment of metals with a mechanically fluidized vacuum machine. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, W.E.

    1997-09-05

    The ERIP project {open_quotes}Automated Thermal Treatment of Metals with a Mechanically Fluidized Vacuum Machine{close_quotes} produced more benefits in unintended areas than in the original intent of the program. The first project was directed to heat treating of solid parts using a retort half filled with fine powder. The treatment of metal powders was not originally envisioned at the time of proposal preparation. This second application, where the powder itself is being treated, has turned out to be multi-billion dollar market in which the Mechanical Fluidized Vacuum machine can create revolutionary changes. Consequently most efforts in recent years have been dedicated to further growth of the powder markets. These efforts procured a second ERIP grant titled {open_quotes}Thermal Heat and Diffusion Treatment of Bulk Powders.{close_quotes}

  6. Reducing Residential Peak Electricity Demand with Mechanical Pre-Cooling of Building Thermal Mass

    Energy Technology Data Exchange (ETDEWEB)

    Turner, Will [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Walker, Iain [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Roux, Jordan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-08-01

    This study uses an advanced airflow, energy and humidity modelling tool to evaluate the potential for residential mechanical pre-cooling of building thermal mass to shift electricity loads away from the peak electricity demand period. The focus of this study is residential buildings with low thermal mass, such as timber-frame houses typical to the US. Simulations were performed for homes in 12 US DOE climate zones. The results show that the effectiveness of mechanical pre-cooling is highly dependent on climate zone and the selected pre-cooling strategy. The expected energy trade-off between cooling peak energy savings and increased off-peak energy use is also shown.

  7. ANALYSIS OF SHAKEDOWN OF FG BREE PLATE SUBJECTED TO COUPLED THERMAL-MECHANICAL LOADINGS

    Institute of Scientific and Technical Information of China (English)

    Xianghe Peng; Ning Hu; Hengwei Zheng; Cuirong Fang

    2009-01-01

    The static and kinematic shakedown of a functionally graded (FG) Bree plate is analyzed. The plate is subjected to coupled constant mechanical load and cyclically varying tem-perature. The material is assumed linearly elastic and nonlinear isotropic hardening with elastic modulus, yield strength and the thermal expansion coefficient varying exponentially through the thickness of the plate. The boundaries between the shakedown area and the areas of elasticity, incremental collapse and reversed plasticity are determined, respectively. The shakedown of the counterpart made of homogeneous material with average material properties is also analyzed. The comparison between the results obtained in the two cases exhibits distinct qualitative and quantitative difference, indicating the importance of shakedown analysis for FG structures. Since FG structures are usually used in the cases where severe coupled cyclic thermal and mechani-cal loadings are applied, the approach developed and the results obtained are significant for the analysis and design of such kind of structures.

  8. Inverse thermoelastic analysis for thermal and mechanical loads identification using FBG data

    Science.gov (United States)

    Nakamura, Toshiya; Kamimura, Yukihiro; Igawa, Hirotaka; Morino, Yoshiki

    2014-12-01

    Fiber Bragg Grating (FBG) sensors have widely been used to monitor temperature and strain distributions as a part of the structural health monitoring system. Since FBG has the sensitivity to the variations in both temperature and strain, a compensation is required to separate the strain or temperature data from the sensor output which is the shift of the grating's Bragg wavelength. The present study develops a computational inverse thermoelastic analysis method to separately identify the thermal and mechanical boundary conditions (loads) from the output of the FBG sensor. Numerical study has been made for a corrugate-core sandwich integral thermal protection system (TPS) to examine the method. The discussion is focused on the computational stability. The results reveal that the identification of the mechanical load is less stable than that of the heat flux. It is also shown that the condition number of a coefficient matrix serves as the index of the stability of the inverse analysis.

  9. Mechanical and Thermal Characteristics of Insulation Materials for the KSTAR Magnet System at Cryogenic Temperature

    Science.gov (United States)

    Chung, Wooho; Lim, Bungsu; Kim, Myungkyu; Park, Hyunki; Kim, Keeman; Chu, Yong; Lee, Sangil

    2004-06-01

    The KSTAR(Korea Superconducting Tokamak Advanced Research) superconducting magnet is electrically insulated by the composite material of epoxy resin and glass fiber (2.5 kV/mm) and Kapton (8 kV/mm). The insulation composite material of epoxy resin and glass fiber is prepared using a VPI (Vacuum Pressure Impregnation) process. The superconducting magnet is under mechanical stress caused by the large temperature difference between the operation temperature of the magnet and room temperature. The large electro-magnetic force during the operation of the magnet is also exerted on the magnet. Therefore, the characteristics of the insulation material at cryogenic temperatures are very important and the tensile stress and thermal expansion coefficient for the insulation materials of the KSTAR superconducting magnet are measured. This paper presents results on mechanical properties of the insulation material for KSTAR magnets, such as density, ultimate tensile stress and thermal contraction between room temperature and cryogenic temperatures.

  10. Thermal and mechanical properties of TPU/PBT reinforced by carbon fiber

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jintao; Liu, Huanyu; Lu, Xiang; Qu, Jinping, E-mail: jpqu@scut.edu.cn [National Engineering Research Center of Novel Equipment for Polymer Processing, The Key Laboratory of Polymer Processing Engineering of the Ministry of Education, South China University of Technology, Guangzhou, 510640, Guangdong (China)

    2016-03-09

    In this study, thermal, mechanical properties and processability were performed on a series of carbon fiber (CF) filled thermoplastic polyurethane (TPU)/poly (butylene terephthalate) (PBT) composites to identify the effect of CF weight fraction on the properties of TPU/PBT. Scanning Electronic Microscope (SEM) show that CFs are uniformly dispersed in TPU/PBT matrix and there are no agglomerations. Melt flow index (MFI) show that the melt viscosity increased with the CF loading. Thermogravimetric analysis (TGA) revealed that the introduction of CF into organic materials tend to improve their thermal stability. The mechanical properties indicated that tensile strength and modulus, flexural strength and modulus, improved with an increase in CF loading, but the impact strength decreased by the loading of CF.

  11. Flexible hybrid energy cell for simultaneously harvesting thermal, mechanical, and solar energies.

    Science.gov (United States)

    Yang, Ya; Zhang, Hulin; Zhu, Guang; Lee, Sangmin; Lin, Zong-Hong; Wang, Zhong Lin

    2013-01-22

    We report the first flexible hybrid energy cell that is capable of simultaneously or individually harvesting thermal, mechanical, and solar energies to power some electronic devices. For having both the pyroelectric and piezoelectric properties, a polarized poly(vinylidene fluoride) (PVDF) film-based nanogenerator (NG) was used to harvest thermal and mechanical energies. Using aligned ZnO nanowire arrays grown on the flexible polyester (PET) substrate, a ZnO-poly(3-hexylthiophene) (P3HT) heterojunction solar cell was designed for harvesting solar energy. By integrating the NGs and the solar cells, a hybrid energy cell was fabricated to simultaneously harvest three different types of energies. With the use of a Li-ion battery as the energy storage, the harvested energy can drive four red light-emitting diodes (LEDs).

  12. Studies on mechanical, thermal and morphological properties of irradiated recycled polyamide and waste rubber powder blends

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Medhat M., E-mail: medhat_smh@yahoo.co [National Center for Radiation Research and Technology, Nasr City, Cairo 11731 (Egypt); Badway, Nagwa A.; Gamal, Azza M. [Chemistry Department, Faculty of Science, Al-Azhar University, Nasr City, Cairo (Egypt); Elnaggar, Mona Y.; Hegazy, El-Sayed A. [National Center for Radiation Research and Technology, Nasr City, Cairo 11731 (Egypt)

    2010-05-01

    The aim of this article was to show the effect of gamma irradiation on mechanical and thermal properties of recycled polyamide (rPA) copolymer blended with different content of waste rubber powder (WRP). In order to study the structural modifications of prepared blends have been subjected to irradiation doses up to 200 kGy were applied to all samples. Non-irradiated blends were used as control samples. Mechanical properties, namely, tensile strength (TS), elastic modulus, elongation at break and hardness have been followed up as a function of irradiation dose and degree of loading with rubber content. Furthermore, the influence of radiation dose in the thermal parameters, melting temperature, heat of fusion, DELTAH{sub f} of the recycled PA and its blend with waste rubber powder (WRP) was also investigated.

  13. Studies on Mechanical, Thermal, and Morphological Properties of Glass Fibre Reinforced Polyoxymethylene Nanocomposite

    Directory of Open Access Journals (Sweden)

    K. Mohan Babu

    2014-01-01

    Full Text Available Polyoxymethylene is a material which has excellent mechanical properties similar to Nylon-6 filled with 30% GF. 75% POM and 25% glass fibre (POMGF were blended with nanoclay to increase the tensile and flexural properties. Samples were extruded in twin screw extruder to blend POMGF and (1%, 3%, and 5% Cloisite 25A nanoclay and specimens were prepared by injection moulding process. The tensile properties, flexural properties, impact strength, and hardness were investigated for the nanocomposites. The fibre pull-outs, fibre matrix adhesion, and cracks in composites were investigated by using scanning electron microscopy. 1% POMGF nanocomposite has low water absorption property. Addition of nanoclay improves the mechanical properties and thermal properties marginally. Improper blending of glass fibre and nanoclay gives low tensile strength and impact strength. SEM image shows the mixing of glass fibre and nanoclay among which 1% POMGF nanocomposite shows better properties compared to others. The thermal stability decreased marginally only with the addition of nanoclay.

  14. Design of Friction Stir Spot Welding Tools by Using a Novel Thermal-Mechanical Approach

    Directory of Open Access Journals (Sweden)

    Zheng-Ming Su

    2016-08-01

    Full Text Available A simple thermal-mechanical model for friction stir spot welding (FSSW was developed to obtain similar weld performance for different weld tools. Use of the thermal-mechanical model and a combined approach enabled the design of weld tools for various sizes but similar qualities. Three weld tools for weld radii of 4, 5, and 6 mm were made to join 6061-T6 aluminum sheets. Performance evaluations of the three weld tools compared fracture behavior, microstructure, micro-hardness distribution, and welding temperature of welds in lap-shear specimens. For welds made by the three weld tools under identical processing conditions, failure loads were approximately proportional to tool size. Failure modes, microstructures, and micro-hardness distributions were similar. Welding temperatures correlated with frictional heat generation rate densities. Because the three weld tools sufficiently met all design objectives, the proposed approach is considered a simple and feasible guideline for preliminary tool design.

  15. NSR&D FY15 Final Report. Modeling Mechanical, Thermal, and Chemical Effects of Impact

    Energy Technology Data Exchange (ETDEWEB)

    Long, Christopher Curtis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ma, Xia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zhang, Duan Zhong [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-02

    The main goal of this project is to develop a computer model that explains and predicts coupled mechanical, thermal and chemical responses of HE under impact and friction insults. The modeling effort is based on the LANL-developed CartaBlanca code, which is implemented with the dual domain material point (DDMP) method to calculate complex and coupled thermal, chemical and mechanical effects among fluids, solids and the transitions between the states. In FY 15, we have implemented the TEPLA material model for metal and performed preliminary can penetration simulation and begun to link with experiment. Currently, we are working on implementing a shock to detonation transition (SDT) model (SURF) and JWL equation of state.

  16. Effect of equilibrium moisture content on barrier, mechanical and thermal properties of chitosan films.

    Science.gov (United States)

    Aguirre-Loredo, Rocío Yaneli; Rodríguez-Hernández, Adriana Inés; Morales-Sánchez, Eduardo; Gómez-Aldapa, Carlos Alberto; Velazquez, Gonzalo

    2016-04-01

    Water molecules modify the properties of biodegradable films obtained from hydrophilic materials. Most studies dealing with thermal, mechanical and barrier properties of hydrophilic films are carried out under one relative humidity (RH) condition. The objective of this work was to evaluate the effect of the moisture content on the thermal, mechanical and barrier properties of chitosan films under several RH conditions. Microclimates, obtained with saturated salt solutions were used for conditioning samples and the properties of the films were evaluated under each RH condition. Chitosan films absorbed up to 40% of moisture at the higher RH studied. The percentage of elongation and the water vapour permeability increased while tensile strength, Young's modulus and glass transition temperature decreased, when the moisture content increased. The results suggest that the water molecules plasticized the polymer matrix, changing the properties when the films were in contact with high RH environments.

  17. Microstructures and Mechanical Properties of Ceramic/Metal Gradient Thermal Barrier Coatings

    Institute of Scientific and Technical Information of China (English)

    XIAO Jin-sheng; JIANG Bing; LIU Jie; HUANG Shi-yong

    2003-01-01

    The ceramic/metal gradient thermal barrier coatings (CMGTBCs) which combined the conceptions of thermal barrier coatings ( TBG ) and functional gradient materials ( FGMs ) are investigated. The structure model studied in this paper is a general model which includes four different layers: pure ceramic layer , ceramic/metal gradient layer, pure metal layer, and substrate layer. The microstructures of gradient layer have different ceramics and metal volume fraction profile along with the direction of thickness. The profile function used to describe the gradient microstructures can be expressed in power-law or polynomial expression. The mechanical properties of CMGTBCs are obtained by means of microscopic mechanics. As special cases, the interactive solutions are given by Mori- Tanaka method, and the non- interactive solutions by dilute solution. The Young's modulus calculated by these methods are compared with those by other methods , e g, the rule of mixtures.

  18. Microstructure evolution and effect on mechanical property in AZ80 Mg alloy during thermal processing

    Institute of Scientific and Technical Information of China (English)

    WANG Qiang; ZHANG Zhi-min; LI Bao-cheng; LI Xu-bin

    2006-01-01

    The microstructure and mechanical properties of AZ80 alloy were investigated during thermal processing. The samples of 4 mm in thickness machined from cast ingot were compressed at 300 ℃ with a thickness reduction of 75% and cooled in the water to room temperature. Then ageing(T5) and solution+ageing (T6) treatments were employed respectively. The results show that mechanical properties are significantly improved after thermal processing than those of as-cast AZ80 alloy due to grain refinement and discontinuous precipitates. The heat treatment has significant influence on microstructural evolution for sample formed at moderate temperature. Microstructural evaluation indicates that the β-phase increases because of sufficient solution and the alloy is strengthened evidently.

  19. Mechanical, thermal and microstructural characteristics of cellulose fibre reinforced epoxy/organoclay nanocomposites

    KAUST Repository

    Alamri, H.

    2012-10-01

    Epoxy nanocomposites reinforced with recycled cellulose fibres (RCFs) and organoclay platelets (30B) have been fabricated and investigated in terms of WAXS, TEM, mechanical properties and TGA. Results indicated that mechanical properties generally increased as a result of the addition of nanoclay into the epoxy matrix. The presence of RCF significantly enhanced flexural strength, fracture toughness, impact strength and impact toughness of the composites. However, the inclusion of 1 wt.% clay into RCF/epoxy composites considerably increased the impact strength and toughness. The presence of either nanoclay or RCF accelerated the thermal degradation of neat epoxy, but at high temperature, thermal stability was enhanced with increased char residue over neat resin. The failure micromechanisms and energy dissipative processes in these nanocomposites were discussed in terms of microstructural observations. © 2012 Published by Elsevier Ltd. All rights reserved.

  20. Synthesis and Characterization of Imide Containing Hybrid Epoxy Resin with Improved Mechanical and Thermal Properties

    Directory of Open Access Journals (Sweden)

    U. G. Rane

    2014-01-01

    Full Text Available Phosphorous containing amine, tripropyldiamine phosphine oxide (TPDAP, and hybrid monomer 4-(N-phthalimidophenyl glycidylether (PPGE were synthesized and characterized by Fourier transform infrared (FTIR spectroscopy, nuclear magnetic resonance (NMR spectroscopy, and elemental analysis (EDX. PPGE was incorporated in bisphenol A epoxy resin (BPA in various concentrations (5% to 20%, based on a weight percentage of BPA resin. Curing was carried out with the stoichiometric amount of TPDAP and 1,3-propanediamine (PDA to result in cross-link network. Various mechanical, chemical, thermal, and flame retardant properties of modified and unmodified epoxy resin were studied. The coatings obtained with the addition of PPGE were found to have improved properties as compared with those of the unmodified resin. Coatings with 15% loading of PPGE showed improved flame retardant and mechanical properties with stable thermal behaviour.

  1. Processing of poly(lactic acid): characterization of chemical structure, thermal stability and mechanical properties

    OpenAIRE

    Carrasco Alonso, Félix Ángel; Pagès Figueras, Pere; Gamez Pérez, José; Santana Pérez, Orlando Onofre; Maspoch Rulduà, Mª Lluïsa

    2010-01-01

    The processing of poly(lactic acid) (injection and extrusion/injection) as well as annealing of processed materials were studied in order to analyze the variation of its chemical structure, thermal degradation and mechanical properties. Processing of PLA was responsible for a decrease in molecular weight, as determined by GPC, due to chain scission. The degree of crystallinity was evaluated by means of differential scanning calorimetry and X-ray diffraction. It was found that mech...

  2. Mechanical and thermal properties of water glass coated sisal fibre-reinforced polypropylene composite

    CSIR Research Space (South Africa)

    Phiri, G

    2012-10-01

    Full Text Available ?C). Figure 1 shows the processing steps followed to produce composite samples. Up to 15% fibre loading could be achieved and the sisal fibres were coated with water glass to improve fire resistance. In order to improve the adhesion between sisal... preparation process: (A) WG coated fibre, (B) High speed granulator, (C) Composite granules, (D) Single screw extruder, (E) Injection moulder and (F) Composite samples (dumbbells) Mechanical and thermal properties of water glass coated sisal fi bre...

  3. Tests and analyses for the mechanical and thermal qualification of the new RFX first wall tiles

    Energy Technology Data Exchange (ETDEWEB)

    Zaccaria, P. E-mail: pierluigi.zaccaria@igi.cnr.it; Dal Bello, S.; Marcuzzi, D

    2003-09-01

    The graphite tiles of the RFX first wall were modified to achieve a more uniform power deposition on the plasma facing surface and to give housing to a large number of in-vessel probes. These design requirements led to a substantial reduction of the tile thickness with respect to the original design. For this reason, the new first wall tiles had to be carefully qualified both from the mechanical and thermal point of view, carrying out experimental tests and analyses.

  4. Analytical Study on Thermal and Mechanical Design of Printed Circuit Heat Exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Su-Jong [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sabharwall, Piyush [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kim, Eung-Soo [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2013-09-01

    The analytical methodologies for the thermal design, mechanical design and cost estimation of printed circuit heat exchanger are presented in this study. In this study, three flow arrangements of parallel flow, countercurrent flow and crossflow are taken into account. For each flow arrangement, the analytical solution of temperature profile of heat exchanger is introduced. The size and cost of printed circuit heat exchangers for advanced small modular reactors, which employ various coolants such as sodium, molten salts, helium, and water, are also presented.

  5. New insulation fiberboards from sunflower cake with improved thermal and mechanical properties

    OpenAIRE

    Evon, Philippe; Vinet, Justine; Rigal, Matthieu; Labonne, Laurent; Vandenbossche, Virginie; Rigal, Luc

    2015-01-01

    International audience; New thermal insulation fiberboards were manufactured by compression molding from a cake generated during the sunflower biorefinery. Fiberboards were cohesive mixtures of a natural binder and lignocellulosic fibers from sunflower cake. The natural binder ensured the board cohesion, and fibers acted as reinforcing fillers. The influence of molding conditions, i.e. binder type and binder content, on board density, mechanical and heat insulation properties was examined. Th...

  6. Mechanical and Thermal Design and Qualification of an Atom Interferometer Sounding Rocket Payload

    Science.gov (United States)

    Grosse, J.; Seidel, S. T.; Krutzik, M.; Wendrich, T.; Stamminger, A.; Scharringhausen, M.; Quantus Consortium

    2015-09-01

    The MAIUS-1 experiment is a pathfinder quantum optics experiment about to fly on a VSB-30 sounding rocket in November 2015. The scientific objective of the mission is to demonstrate the feasibility of creating a Bose-Einstein Condensate and performing atom interferometry aboard a sounding rocket with Rubidium 87atoms. This paper will summarize the thermal and mechanical design of the payload and its (sub)systems. Moreover the qualification procedures and the results of the qualification test will be presented.

  7. Mechanical and thermal analysis of the internal combustion engine piston using Ansys

    Science.gov (United States)

    Cioată, V. G.; Kiss, I.; Alexa, V.; Raţiu, S. A.

    2017-01-01

    The piston is one of the most important components of the internal combustion engine. Piston fail mainly due to mechanical stresses and thermal stresses. In this paper is determined by using the finite element method, stress and displacement distribution due the flue gas pressure and temperature, separately and combined. The FEA is performed by CAD and CAE software. The results are compared with those obtained by the analytical method and conclusions have been drawn.

  8. Preparation and thermal decomposition mechanism of Mg,Al-hydrotalcite nano-crystals with titania doping

    Institute of Scientific and Technical Information of China (English)

    REN Qing-li; LUO Qiang

    2006-01-01

    The highly pure nano-crystal Mg,Al-hydrotalcite with titania doping was synthesized by one-step liquid reaction method at atmospheric pressure. The preparation of the Mg,Al-hydrotalcite nano-crystal after doping titania was investigated according to the results of XRD,TEM,IR and DSC. Moreover,based on the DSC test results,the thermal mechanism functions of the Mg,Al-hydrotalcite with titania doping were studied after calculation and comparison.

  9. Thermal and Mechanical Properties of Isotactic Polypropylene/TiO2 Particulate Composites

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Particulate composites based on isotactic polypropylene(iPP) and titanium dioxide(TiO2) have been prepared and their morphology and thermal behavior investigated by scan-ning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermo-gravimetric analysis(TGA). Tensile tests were performed to assess the influence of TiO2 onthe mechanical properties of the iPP.

  10. Synthesis and mechanism of formation of oxadeazaflavines by microwave thermal cyclization of ortho-halobenzylidene barbiturates

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa-Villar, J. Daniel; Oliveira, Sandra C.G. de, E-mail: figueroa@ime.eb.br [Grupo de Quimica Medicinal, Departamento de Quimica, Instituto Militar de Engenharia, Rio de Janeiro, RJ (Brazil)

    2011-09-15

    The thermal cyclization reaction of o-halobenzylidene barbiturates was developed as an efficient and simple method for the preparation of oxadeazaflavines. The use of solid state reaction conditions with microwave irradiation afforded the products in 5 min with 47 to 98% yield. Experimental synthetic results and thermogravimetric reaction analyses agree with the molecular modeling mechanism simulation, indicating that this reaction occurs through an intramolecular hetero-Diels-Alder cyclization followed by fast re-aromatization. (author)

  11. Study on the Thermal and Mechanical Properties of the UV-cured SL5510 Stereolithography Material

    Institute of Scientific and Technical Information of China (English)

    HUANG Bi-wu; HUANG Shu-huai; MO Jian-hua

    2005-01-01

    In recent years, Vantico A &T US Incorporation has developed a type of the hightest accuracy photosensitive resin:SL5510 stereolithography material (briefly named SL5510)to use in the stereolithography apparatus(SLA). In this paper, the thermal and mechanical properties were investigated for the fabricated specimens of SL5510 in the different UV post-cure time. This may instruct us to employ better the fabricated parts of SL5510.

  12. Effects of voids on thermal-mechanical reliability of lead-free solder joints

    Directory of Open Access Journals (Sweden)

    Benabou Lahouari

    2014-06-01

    Full Text Available Reliability of electronic packages has become a major issue, particularly in systems used in electrical or hybrid cars where severe operating conditions must be met. Many studies have shown that solder interconnects are critical elements since many failure mechanisms originate from their typical response under thermal cycles. In this study, effects of voids in solder interconnects on the electronic assembly lifetime are estimated based on finite element simulations.

  13. Influencing Factors of Thermal Deformation on Hydrostatic Pressure Mechanical Seal and Optimization of Rotating and Stationary Rings

    Directory of Open Access Journals (Sweden)

    Lin Dong

    2013-02-01

    Full Text Available According to thermo-elastic deformation theory, take the temperature field analysis results of hydrostatic pressure mechanical seal as volume load to resolve the problem of thermal-structure coupling deformation of rotating and stationary rings in ANSYS software. The distribution laws of thermal strain, thermal stress and thermal-structure coupling deformation are obtained. The effects of working, material and structural parameters on axial, radial thermal deformation and deformation taper of the end faces are discussed in detail, and the main affecting factors are found out. Measures and structural constraint programs to control the thermal deformation are put forward. Base on the theory of thermal deformation compensation, the rotating and stationary rings are optimized, and the thermal deformation before and after their optimization are solved respectively and analyzed comparatively to verify the feasibility of the optimization program.

  14. Thermal-Hydrologic-Mechanical Behavior of Single Fractures in EGS Reservoirs

    Science.gov (United States)

    Zyvoloski, G.; Kelkar, S.; Yoshioka, K.; Rapaka, S.

    2010-12-01

    Enhanced Geothermal Systems (EGS) rely on the creation a connected fracture system or the enhancement of existing (natural) fractures by hydraulic and chemical treatments. EGS studies at Fenton Hill (New Mexico, USA) and Hijiori (Japan) have revealed that only a limited number of fractures contribute to the effective heat transfer surface area. Thus, the economic viability of EGS depends strongly on the creation and spacing of single fractures in order to efficiently mine heat from given volume of rock. Though there are many similarities between EGS and natural geothermal reservoirs, a major difference between the reservoir types is the (typically) high pumping pressures and induced thermal stresses at the injection wells of an EGS reservoir. These factors can be responsible for fracture dilation/extension and thermal short circuiting and depend strongly on the surrounding state of stress in the reservoir and mechanical properties. We will present results from our study of the thermal-hydrologic-mechanical (THM) behavior of a single fracture in a realistic subsurface stress field. We will show that fracture orientation, the stress environment, fracture permeability structure, and the relationship between permeability changes in a fracture resulting from mechanical displacement are all important when designing and managing an EGS reservoir. Lastly, we present a sensitivity analysis of the important parameters that govern fracture behavior with respect to field measurements. Temperature in high permeability fracture in an EGS reservoir

  15. Significant Enhancement of Mechanical and Thermal Properties of Thermoplastic Polyester Elastomer by Polymer Blending and Nanoinclusion

    Directory of Open Access Journals (Sweden)

    Manwar Hussain

    2016-01-01

    Full Text Available Thermoplastic elastomer composites and nanocomposites were fabricated via melt processing technique by blending thermoplastic elastomer (TPEE with poly(butylene terephthalate (PBT thermoplastic and also by adding small amount of organo modified nanoclay and/or polytetrafluoroethylene (PTFE. We study the effect of polymer blending on the mechanical and thermal properties of TPEE blends with and without nanoparticle additions. Significant improvement was observed by blending only TPEE and virgin PBT polymers. With a small amount (0.5 wt.% of nanoclay or PTFE particles added to the TPEE composite, there was further improvement in both the mechanical and thermal properties. To study mechanical properties, flexural strength (FS, flexural modulus (FM, tensile strength (TS, and tensile elongation (TE were all investigated. Thermogravimetric analysis (TGA and differential scanning calorimetry (DSC were used to analyze the thermal properties, including the heat distortion temperature (HDT, of the composites. Scanning electron microscopy (SEM was used to observe the polymer fracture surface morphology. The dispersion of the clay and PTFE nanoparticles was confirmed by transmission electron microscopy (TEM analysis. This material is proposed for use as a baffle plate in the automotive industry, where both high HDT and high modulus are essential.

  16. Degradation mechanism and thermal stability of urea nitrate below the melting point

    Energy Technology Data Exchange (ETDEWEB)

    Desilets, Sylvain, E-mail: sylvain.desilets@drdc-rddc.gc.ca [Defence R and D Canada, Valcartier, 2459 Pie-XI Blvd North, Val-Belair, Quebec, Canada G3J 1X5 (Canada); Brousseau, Patrick; Chamberland, Daniel [Defence R and D Canada, Valcartier, 2459 Pie-XI Blvd North, Val-Belair, Quebec, Canada G3J 1X5 (Canada); Singh, Shanti; Feng, Hongtu; Turcotte, Richard [Canadian Explosives Research Laboratory, 1 Haanel Dr. Ottawa, Quebec, Canada K1A 1M1 (Canada); Anderson, John [Defence R and D Canada, Suffield, Box 4000, stn Main, Medicine Hat, Alberta, Canada T1A 8K6 (Canada)

    2011-07-10

    Highlights: {yields} Decomposition mechanism of urea nitrate. {yields} Spectral characterization of the decomposition mechanism. {yields} Thermal stability of urea nitrate at 50, 70 and 100 {sup o}C. {yields} Chemical balance of decomposed products released. - Abstract: Aging and degradation of urea nitrate below the melting point, at 100 {sup o}C, was studied by using thermal analysis and spectroscopic methods including IR, Raman, {sup 1}H and {sup 13}C NMR techniques. It was found that urea nitrate was completely degraded after 72 h at 100 {sup o}C into a mixture of solids (69%) and released gaseous species (31%). The degradation mechanism below the melting point was clearly identified. The remaining solid mixture was composed of ammonium nitrate, urea and biuret while unreacted residual nitric and isocyanic acids as well as traces of ammonia were released as gaseous species at 100 {sup o}C. The thermal stability of urea nitrate, under extreme storage conditions (50 {sup o}C), was also examined by isothermal nano-calorimetry.

  17. Curing Kinetics, Mechanical Properties and Thermal Stability of Epoxy/Graphene Nanoplatelets (GNPs) Powder Coatings

    Institute of Scientific and Technical Information of China (English)

    ZHI Maoyong; HUANG Wanxia

    2016-01-01

    Epoxy/graphene nanoplatelets (GNPs) powder coatings were fabricated using ultrasonic pre-dispersion of GNPs and melt-blend extrusion method. The isothermal curing kinetics of epoxy/GNPs powder coating were monitored by means of real-time Fourier transform infrared spectroscopy (FT-IR) with a heating cell. The mechanical properties of the epoxy/GNPs cured coatings had been investigated, by evaluating their fracture surfaces with ifeld-emission scanning electron microscopy (FE-SEM) after three-point-bending tests. The thermal stability of the epoxy/GNPs cured coatings was studied by thermo-gravimetric analysis (TGA). The isothermal curing kinetics result showed that the GNPs would not affect the autocatalytic reaction mechanism, but the loading of GNPs below 1.0 wt % additive played a prompting role in the curing of the epoxy/GNPs powder coatings. The fracture strain, fracture toughness and impact resistance of the epoxy/GNPs cured coatings increased dramatically at low levels of GNPs loading (1 wt %), indicating that the GNPs could improve the toughness of the epoxy/GNPs powder coatings. Furthermore, from FE-SEM studies of the fracture surfaces, the possible toughening mechanisms of the epoxy/GNPs cured coatings were proposed. TGA result showed that the incorporation of GNPs improved the thermal stability of the cured coatings. Hence, the GNPs modiifed epoxy can be an efifcient approach to toughen epoxy powder coating along with improving their thermal stability.

  18. Thermal-mechanical study of functionally graded dental implants with the finite element method.

    Science.gov (United States)

    Wang, F; Lee, H P; Lu, C

    2007-01-01

    This article investigates the thermal-mechanical performance of hydroxyapatite/titanium (HA/Ti) functionally graded (FG) dental implants with the three-dimensional finite element method. The stresses induced by occlusal force for the present HA/Ti FG implant are calculated to compare with the corresponding stresses for the titanium dental implant. Thermal-mechanical effect of temperature variation due to daily oral activity is also studied. The HA/Ti FG dental implant performance is evaluated against the maximum von Mises stress, which is the general performance indicator, the first principal/tensile stress for mechanical failure of implant-bone-bond and the third principal/compressive stress for bone absorption. Simulation results indicate that under the influence of occlusal force only, the FG implants with different HA fraction along the implant length perform almost equally well, while the titanium implant sustains much higher von Mises stress. However, when thermal stress is also considered, the FG implant having HA fraction exponential index of m = 2 with temperature decrease of 20 degrees C yields the highest first principal and von Mises stresses among all the FG and titanium implants.

  19. Microstructural, mechanical, and thermal characteristics of recycled cellulose fiber-halloysite-epoxy hybrid nanocomposites

    KAUST Repository

    Alamri, H.

    2012-02-26

    Epoxy hybrid-nanocomposites reinforced with recycled cellulose fibers (RCF) and halloysite nanotubes (HNTs) have been fabricated and investigated. The dispersion of HNTs was studied by synchrotron radiation diffraction (SRD) and transmission electron microscopy (TEM). The influences of RCF/HNTs dispersion on the mechanical properties and thermal properties of these composites have been characterized in terms of flexural strength, flexural modulus, fracture toughness, impact toughness, impact strength, and thermogravimetric analysis. The fracture surface morphology and toughness mechanisms were investigated by SEM. Results indicated that mechanical properties increased because of the addition of HNTs into the epoxy matrix. Flexural strength, flexural modulus, fracture toughness, and impact toughness increased by 20.8, 72.8, 56.5, and 25.0%, respectively, at 1 wt% HNTs load. The presence of RCF dramatically enhanced flexural strength, fracture toughness, impact strength, and impact toughness of the composites by 160%, 350%, 444%, and 263%, respectively. However, adding HNTs to RCF/epoxy showed only slight enhancements in flexural strength and fracture toughness. The inclusion of 5 wt% HNTs into RCF/epoxy ecocomposites increased the impact toughness by 27.6%. The presence of either HNTs or RCF accelerated the thermal degradation of neat epoxy. However, at high temperature, samples reinforced with RCF and HNTs displayed better thermal stability with increased char residue than neat resin. © 2012 Society of Plastics Engineers.

  20. The Interferon-signature of Sjögren’s Syndrome: How Unique Biomarkers Can Identify Underlying Inflammatory and Immunopathological Mechanisms of Specific Diseases

    Directory of Open Access Journals (Sweden)

    Cuong eNguyen

    2013-07-01

    Full Text Available Innate immune responses direct the nature and specificity of downstream adaptive responses in autoimmune diseases. One of the strongest markers of innate immunity is the up-regulated expression of interferon (IFN and IFN-responsive/stimulated genes (IRGs/ISGs. While multiple IRGs are induced during the innate phase of host responses, transcriptome data suggest unique IRG-signatures for different diseases. Sjögren’s syndrome (SjS is characterized by chronic immune attacks against exocrine glands leading to exocrine dysfunction, plus strong up-regulated expressions of IFN IRG transcripts. Genome-wide transcriptome analyses indicate that differentially-expressed IRGs are restricted during disease development and therefore define underlying etiopathological mechanisms. Here we review the innate immune-associated IFN-signature of SjS and show how differential gene expressions of IRG/ISG sets interact molecularly and biologically to identify critical details of SjS etiopathogenesis.

  1. Synthesis of Nano Conducting Polymer Based Polyaniline and it's Composite: Mechanical Properties, Conductivity and Thermal Studies

    Directory of Open Access Journals (Sweden)

    M. Banimahd Keivani

    2010-01-01

    Full Text Available Polyaniline (PAn was prepared chemically in the presence of bronsted acid from aqueous solutions. Polyaniline- nylon 6 composite (termed as PAn/Ny6 prepared via solvent casting method. The preparation conditions were optimized with regard to the mechanical properties of the polymer composite. It was found that the molar ratio of PAn to nylon have the greatest effect in determining the mechanical properties of polymer composite. Electrical conductivity was measured using standard method of four point probe. Spectrophotometric analysis (UV-Vis was used for investigation of the effect of thermal treatment on polyaniline and it’s composite.

  2. Efficient Simulation and Abuse Modeling of Mechanical-Electrochemical-Thermal Phenomena in Lithium-Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Santhanagopalan, Shriram [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Smith, Kandler A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Graf, Peter A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pesaran, Ahmad A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Zhang, Chao [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lamb, Joshua [Sandia National Laboratories; Abraham, Daniel [Argonne National Laboratory; Dees, Dennis [Argonne National Laboratory; Yao, Pierre [Argonne National Laboratory

    2017-08-08

    NREL's Energy Storage team is exploring the effect of mechanical crush of lithium ion cells on their thermal and electrical safety. PHEV cells, fresh as well as ones aged over 8 months under different temperatures, voltage windows, and charging rates, were subjected to destructive physical analysis. Constitutive relationship and failure criteria were developed for the electrodes, separator as well as packaging material. The mechanical models capture well, the various modes of failure across different cell components. Cell level validation is being conducted by Sandia National Laboratories.

  3. Mechanical and thermal properties of green polylactide composites with natural fillers.

    Science.gov (United States)

    Lezak, Emil; Kulinski, Zbigniew; Masirek, Robert; Piorkowska, Ewa; Pracella, Mariano; Gadzinowska, Krystyna

    2008-12-08

    Green composites of PLA with micropowders derived from agricultural by-products such as oat husks, cocoa shells, and apple solids that remain after pressing have been prepared by melt mixing. The thermal and mechanical properties of the composites, including the effect of matrix crystallization and plasticization with poly(propylene glycol), have been studied. All fillers nucleated PLA crystallization and decreased the cold-crystallization temperature. They also affected the mechanical properties of the compositions, increasing the modulus of elasticity but decreasing the elongation at break and tensile impact strength although with few exceptions. Plasticization of the PLA matrix improved the ductility of the composites.

  4. Synthesis and properties of 1,3,5-benzene periodic mesoporous organosilica (PMO): novel aromatic PMO with three point attachments and unique thermal transformations.

    Science.gov (United States)

    Kuroki, Masakatsu; Asefa, Tewodros; Whitnal, Wesley; Kruk, Michal; Yoshina-Ishii, Chiaki; Jaroniec, Mietek; Ozin, Geoffrey A

    2002-11-20

    A new aromatic periodic mesoporous organosilica material containing benzene functional groups that are symmetrically integrated with three silicon atoms in an organosilica mesoporous framework is reported. The material has a high surface area, well-ordered mesoporous structure and thermally stable framework aromatic groups. The functional aromatic moieties were observed to undergo sequential thermal transformation from a three to two and then to a one point attachment within the framework upon continuous thermolysis under air before eventually being converted to periodic mesoporous silica devoid of aromatic groups at high temperatures and longer pyrolysis times. The mesoporosity of the material was characterized by powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), and nitrogen porosimetry, whereas the presence and transformation of the aromatic groups in the walls of the materials were characterized by solid-state NMR spectroscopy, mass spectrometry, and thermogravimetric analysis. The attachment of a benzene ring symmetrically onto three siloxanes of the framework was used advantageously as a cross-linker to enhance the thermal stability of the organic group. Some of these properties are investigated in comparison with other aromatic PMOs that have only two point attachments and an amorphous phenylsilica gel that has only one point attachment. The successful synthesis of the first aromatic PMO with its organic group attached within the framework through more than two points is an important step toward the synthesis of PMOs having organic groups with more complex and multiple attachments within the framework.

  5. Optical tests of a space mechanism under an adverse environment: GAIA secondary mirror mechanism under vaccum and thermal controlled conditions

    Science.gov (United States)

    Ramos Zapata, Gonzalo; Sánchez Rodríguez, Antonio; Belenguer Dávila, Tomás; Urgoiti, Eduardo; Ramírez Quintana, Argiñe

    2007-09-01

    In this work, the optical evaluation of a mechanism for space applications under vacuum and temperature controlled conditions at the facilities of the Space Instrumentation Laboratory (LINES) of the Aerospace Technical Nacional Institute of Spain (INTA) is reported. The mechanism was developed by the Spanish company SENER to fulfill the high performance requirements from ESA technology preparatory program for GAIA Astrometric Mission; in particular, a five degrees of freedom (dof), three translations and two rotations positioning mechanism for the secondary mirror of the GAIA instrument. Both interferometric tests and autocollimator measurements have been combined in order to extract the information about the accuracy of the mechanism movements as well as their repeatability under adverse environmental conditions: vacuum and thermal controlled conditions, up to a 10 -6mbar and 100K. The scope of this paper will cover the measurements concept selection, the presentation of verification activities, the results of such dedicated optical measurements, the correlation with the mechanical models and a brief description of the design process followed to meet the test requirements.

  6. Thermal Explosion in Al-Ni System: Influence of Mechanical Activation

    Science.gov (United States)

    White, Jeremiah D. E.; Reeves, Robert V.; Son, Steven F.; Mukasyan, Alexander S.

    2009-10-01

    The influence of short-term (5-15 min) highly energetic ball milling on the ignition characteristics of a gasless heterogeneous Ni-Al reactive system has been investigated. By using Al-Ni clad particles (30-40 μm diameter Al spheres coated by a 3-3.5 μm layer of Ni, that corresponds to a 1:1 Ni/Al atomic ratio), it was shown that such mechanical treatment leads to a significant decrease in the self-ignition temperature of the system. For example, after 15 min of ball milling, the ignition temperature appears to be ˜600 K, well below the eutectic (913 K) in the considered binary system, which is the ignition temperature for the initial clad particles. Thus, it was demonstrated that the thermal explosion process for mechanically treated reactive media can be solely defined by solid-state reactions. Additionally, thermal analysis measurements revealed that mechanical activation results in a substantial decrease in the effective activation energy (from 84 to 28 kcal/mol) of interaction between Al and Ni. This effect, that is, mechanical activation of chemical reaction, is connected to a substantial increase of contact area between reactive particles and fresh interphase boundaries formed in an inert atmosphere during ball milling. It is also important that by varying the time of mechanical activation one can precisely control the ignition temperature in high-density energetic heterogeneous systems.

  7. Enhanced mechanical behavior of a nanocrystallised stainless steel and its thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Roland, T. [ICD, LASMIS, University of Technology of Troyes, 10010 Troyes (France); Retraint, D. [ICD, LASMIS, University of Technology of Troyes, 10010 Troyes (France)]. E-mail: delphine.retraint@utt.fr; Lu, K. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110015 (China); Lu, J. [Department of Mechanical Engineering, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

    2007-02-15

    This paper discusses the mechanical properties of a nanocrystallised stainless steel obtained using surface mechanical attrition treatment (SMAT) and the underlying grain refinement mechanism using transmission electron microscopy (TEM). It was shown that grain refinement down to the nanometer range has the potential to significantly improve the mechanical properties of a 316L stainless steel which becomes comparable in strength to titanium alloys. Hence, promising structural applications could be considered for such a material. At the same time, the thermal stability of this nanocrystallised material was studied in the temperature range from 100 to 800 deg. C. The results show that the nanometer scaled microstructure is retained up to 600 deg. C and that a controlled annealing treatment could even lead to enhancement of both strength and ductility of this material. All these results are explained in terms of microstructural investigations, X-ray diffraction measurements, tensile and bending tests as well as microhardness measurements.

  8. Thermal-mechanical Numerical Models of Evolution For Different Precambrian Collisional Zones

    Science.gov (United States)

    Parphenuk, O.

    Precambrian continental shields such as the Anabar, Baltic and Canadian, are the structurally stable areas for at least the last 1.6 Ga. Deeply eroded structures of the shields formed in the process of multistage tectonic evolution including horizontal shortening and collision by overthrusting expose at the surface middle to the lower crustal rocks uplifted along the faults from the depths 20-40 km. Thermal-mechanical model of horizontal shortening and continental crust formation in collisional zones is developed and applied to the modelling of thermal and dynamic evolution of different Archean and Proterozoic structures. The thermal structure of the lithosphere subjected to compression and shortening resulted in crustal thickening determines in large scale the further tectonic and thermal evolution of collisional zones. The lithospheric exten- sion in orogenic structures can be the possible reaction to the increase of vertical stress due to the uplift and crustal roots formation. But the number of examples exist of the areas which did not experience post-orogenic extension: the collisional structures of the Anabar Shield, the Kapuskasing structural zone of the Canadian Shield etc. The numerical modelling of the process of brittle overthrusting in the upper crust and the lower crustal viscous flow demonstrated the possibility of different structural forma- tions with thickened upper crust, uplift at the surface and progressively increasing erosion level of the rocks exumated from different depths. The thermal and rheolog- ical conditions are discussed for the formation and preservation of crustal roots. The topography of the uplift and crustal roots strongly depends on the number of param- eters, the most important of which are the viscosity values and contrast for the lower crust and lithospheric upper mantle, the initial dip angle of fault, the rate of shortening and erosion, the thermal regime of the region.

  9. Numerical analysis of thermal impact on hydro-mechanical properties of clay

    Directory of Open Access Journals (Sweden)

    Xuerui Wang

    2014-10-01

    Full Text Available As is known, high-level radioactive waste (HLW is commonly heat-emitting. Heat output from HLW will dissipate through the surrounding rocks and induce complex thermo-hydro-mechanical-chemical (THMC processes. In highly consolidated clayey rocks, thermal effects are particularly significant because of their very low permeability and water-saturated state. Thermal impact on the integrity of the geological barriers is of most importance with regard to the long-term safety of repositories. This study focuses on numerical analysis of thermal effects on hydro-mechanical properties of clayey rock using a coupled thermo-mechanical multiphase flow (TH2M model which is implemented in the finite element programme OpenGeoSys (OGS. The material properties of the numerical model are characterised by a transversal isotropic elastic model based on Hooke's law, a non-isothermal multiphase flow model based on van Genuchten function and Darcy's law, and a transversal isotropic heat transport model based on Fourier's law. In the numerical approaches, special attention has been paid to the thermal expansion of three different phases: gas, fluid and solid, which could induce changes in pore pressure and porosity. Furthermore, the strong swelling and shrinkage behaviours of clayey material are also considered in the present model. The model has been applied to simulate a laboratory heating experiment on claystone. The numerical model gives a satisfactory representation of the observed material behaviour in the laboratory experiment. The comparison of the calculated results with the laboratory findings verifies that the simulation with the present numerical model could provide a deeper understanding of the observed effects.

  10. Numerical analysis of thermal impact on hydro-mechanical properties of clay

    Institute of Scientific and Technical Information of China (English)

    Xuerui Wang; Hua Shao; Jürgen Hesser; Chunliang Zhang; Wenqing Wang; Olaf Kolditz

    2014-01-01

    As is known, high-level radioactive waste (HLW) is commonly heat-emitting. Heat output from HLW will dissipate through the surrounding rocks and induce complex thermo-hydro-mechanical-chemical (THMC) processes. In highly consolidated clayey rocks, thermal effects are particularly significant because of their very low permeability and water-saturated state. Thermal impact on the integrity of the geological barriers is of most importance with regard to the long-term safety of repositories. This study focuses on numerical analysis of thermal effects on hydro-mechanical properties of clayey rock using a coupled thermo-mechanical multiphase flow (TH2M) model which is implemented in the finite element programme OpenGeoSys (OGS). The material properties of the numerical model are characterised by a transversal isotropic elastic model based on Hooke’s law, a non-isothermal multiphase flow model based on van Genuchten function and Darcy’s law, and a transversal isotropic heat transport model based on Fourier’s law. In the numerical approaches, special attention has been paid to the thermal expansion of three different phases: gas, fluid and solid, which could induce changes in pore pressure and porosity. Furthermore, the strong swelling and shrinkage behaviours of clayey material are also considered in the present model. The model has been applied to simulate a laboratory heating experiment on claystone. The numerical model gives a satisfactory representation of the observed material behaviour in the laboratory experiment. The comparison of the calculated results with the laboratory findings verifies that the simulation with the present numerical model could provide a deeper understanding of the observed effects.

  11. Reduced silanized graphene oxide/epoxy-polyurethane composites with enhanced thermal and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jing, E-mail: linjin00112043@126.com [School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006 (China); Zhang, Peipei [Worcester Polytechnic Institute, Worcester, MA 01605 (United States); Zheng, Cheng; Wu, Xu; Mao, Taoyan; Zhu, Mingning; Wang, Huaquan; Feng, Danyan; Qian, Shuxuan; Cai, Xianfang [School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006 (China)

    2014-10-15

    Graphical abstract: The synthesis route for EPUAs/R-Si-GEO composites. - Highlights: • Reduced silanized graphene oxide as fillers. • The graphene layers were well distributed in the epoxy-polyurethane composites. • The thermal stabilities of composites were greatly improved by incorporation of the graphene. • Mechanical properties of composites were greatly enhanced by the incorporation of the graphene. - Abstract: This paper describes the synthesis of reduced silanized graphene oxide/epoxy-polyurethane (EPUAs/R-Si-GEO) composites with enhanced thermal and mechanical properties. Graphene oxide (GEO), prepared from natural graphite flakes, was modified with methacryloxypropyltrimethoxysilane to prepare silanized GEO (Si-GEO), and was then reduced by NaHSO{sub 3} to prepare R-Si-GEO (partially reduced Si-GEO). EPAc/R-Si-GEO (R-Si-GEO/epoxy acrylate copolymers) was synthesized via an in situ polymerization of R-Si-GEO and epoxy acrylic monomers. EPUAs/R-Si-GEO was obtained by curing reaction between EPAc/R-Si-GEO and an isocyanate curing agent. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were used to characterize the surface and crystal structure of the modified graphene and EPUAs/R-Si-GEO. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize their morphology. Thermal gravimetric analysis (TGA), tensile strength, elongation at break, and cross-linking density measurements showed that the thermal stability and mechanical properties of EPUAs/R-Si-GEO were greatly enhanced by the addition of R-Si-GEO.

  12. Thermal Stability, Combustion Behavior, and Mechanical Property in a Flame-Retardant Polypropylene System

    Directory of Open Access Journals (Sweden)

    Lili Wang

    2017-01-01

    Full Text Available In order to comprehensively improve the strength, toughness, flame retardancy, smoke suppression, and thermal stability of polypropylene (PP, layered double hydroxide (LDH Ni0.2Mg2.8Al–LDH was synthesized by a coprecipitation method coupled with the microwave-hydrothermal treatment. The X-ray diffraction (XRD, morphology, mechanical, thermal, and fire properties for PP composites containing 1 wt %–20 wt % Ni0.2Mg2.8Al–LDH were investigated. The cone calorimeter tests confirm that the peak heat release rate (pk–HRR of PP–20%LDH was decreased to 500 kW/m2 from the 1057 kW/m2 of PP. The pk–HRR, average mass loss rate (AMLR and effective heat of combustion (EHC analysis indicates that the condensed phase fire retardant mechanism of Ni0.2Mg2.8Al–LDH in the composites. The production rate and mean release yield of CO for composites gradually decrease as Ni0.2Mg2.8Al–LDH increases in the PP matrix. Thermal analysis indicates that the decomposition temperature for PP–5%LDH and PP–10%LDH is 34 °C higher than that of the pure PP. The mechanical tests reveal that the tensile strength of PP–1%LDH is 7.9 MPa higher than that of the pure PP. Furthermore, the elongation at break of PP–10%LDH is 361% higher than PP. In this work, the synthetic LDH Ni0.2Mg2.8Al–LDH can be used as a flame retardant, smoke suppressant, thermal stabilizer, reinforcing, and toughening agent of PP products.

  13. Effect of gamma irradiation on mechanical, thermal and rheological behavior of HDPE filled with seaweed residues

    Energy Technology Data Exchange (ETDEWEB)

    Catano, L. [Universidad Central de Venezuela, Facultad de Ingenieria, Escuela de Ingenieria Quimica, Caracas 1041 A (Venezuela); Albano, C. [Universidad Central de Venezuela, Facultad de Ingenieria, Escuela de Ingenieria Quimica, Caracas 1041 A (Venezuela) and Centro de Quimica, Laboratorio de Polimeros, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020 A (Venezuela)]. E-mail: calbano@ivic.ve; Karam, A. [Centro de Quimica, Laboratorio de Polimeros, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020 A (Venezuela)]. E-mail: akaram@quimica.ivic.ve; Dominguez, N. [Centro de Quimica, Laboratorio de Polimeros, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020 A (Venezuela); Sanchez, Y. [Centro de Quimica, Laboratorio de Polimeros, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020 A (Venezuela); Gonzalez, J. [Departamento de Mecanica, Universidad Simon Bolivar, Caracas 1080 (Venezuela)

    2005-07-01

    The present work shows the results obtained during the investigation of the influence of gamma irradiation on mechanical, thermal and rheological properties of high-density polyethylene (HDPE) filled with seaweed residues (SR). The SR used was located on Venezuelan coastlines and they are composed mainly by CaCO{sub 3} in aragonite phase. The HDPE was extruded along with the filler at different compositions (20, 30 and 40 wt.%). The composites were exposed to a {sup 60}Co source irradiated at 25 and 100 kGy. From the obtained results, it was noticed that Young modulus remained constant with filler content. Moreover, the influence of filler content was found to be more prominent on properties like tensile stress and elongation at break. On the other hand, thermal analysis showed that filler content had no significant influence on thermal stability. Still, it is necessary to point out that low radiation doses improved thermal stability of the composites. From rheological studies it was observed a decreasing of melt flow index (MFI) by increasing the SR amount and radiation. Therefore, was determinate that high filler content composites are the best choice to be considered for biomedical and industrial applications.

  14. Failure Mechanisms of SAC/Fe-Ni Solder Joints During Thermal Cycling

    Science.gov (United States)

    Gao, Li-Yin; Liu, Zhi-Quan; Li, Cai-Fu

    2017-08-01

    Thermal cycling tests have been conducted on Sn-Ag-Cu/Fe- xNi ( x = 73 wt.% or 45 wt.%) and Sn-Ag-Cu/Cu solder joints according to the Joint Electron Device Engineering Council industrial standard to study their interfacial reliability under thermal stress. The interfacial intermetallic compounds formed for solder joints on Cu, Fe-73Ni, and Fe-45Ni were 4.5 μm, 1.7 μm, and 1.4 μm thick, respectively, after 3000 cycles, demonstrating excellent diffusion barrier effect of Fe-Ni under bump metallization (UBM). Also, two deformation modes, viz. solder extrusion and fatigue crack formation, were observed by scanning electron microscopy and three-dimensional x-ray microscopy. Solder extrusion dominated for solder joints on Cu, while fatigue cracks dominated for solder joints on Fe-45Ni and both modes were detected for those on Fe-73Ni. Solder joints on Fe-Ni presented inferior reliability during thermal cycling compared with those on Cu, with characteristic lifetime of 3441 h, 3190 h, and 1247 h for Cu, Fe-73Ni, and Fe-45Ni UBM, respectively. This degradation of the interfacial reliability for solder joints on Fe-Ni is attributed to the mismatch in coefficient of thermal expansion (CTE) at interconnection level. The CTE mismatch at microstructure level was also analyzed by electron backscatter diffraction for clearer identification of recrystallization-related deformation mechanisms.

  15. Cardiac function in an endothermic fish: cellular mechanisms for overcoming acute thermal challenges during diving.

    Science.gov (United States)

    Shiels, H A; Galli, G L J; Block, B A

    2015-02-07

    Understanding the physiology of vertebrate thermal tolerance is critical for predicting how animals respond to climate change. Pacific bluefin tuna experience a wide range of ambient sea temperatures and occupy the largest geographical niche of all tunas. Their capacity to endure thermal challenge is due in part to enhanced expression and activity of key proteins involved in cardiac excitation-contraction coupling, which improve cardiomyocyte function and whole animal performance during temperature change. To define the cellular mechanisms that enable bluefin tuna hearts to function during acute temperature change, we investigated the performance of freshly isolated ventricular myocytes using confocal microscopy and electrophysiology. We demonstrate that acute cooling and warming (between 8 and 28°C) modulates the excitability of the cardiomyocyte by altering the action potential (AP) duration and the amplitude and kinetics of the cellular Ca(2+) transient. We then explored the interactions between temperature, adrenergic stimulation and contraction frequency, and show that when these stressors are combined in a physiologically relevant way, they alter AP characteristics to stabilize excitation-contraction coupling across an acute 20°C temperature range. This allows the tuna heart to maintain consistent contraction and relaxation cycles during acute thermal challenges. We hypothesize that this cardiac capacity plays a key role in the bluefin tunas' niche expansion across a broad thermal and geographical range. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  16. Electric and thermal conduction mechanisms of submicron-structured Ni-ZrO2 composites

    Institute of Scientific and Technical Information of China (English)

    范秋林; 胡行方; 郭景坤

    1995-01-01

    The experimental results indicate that the Ni-ZrO2 composites synthesized with urn-sized Ni powder and nm-sized ZrO2 powder possess submicron structure. Based on the fractal theory, the relationship between the electric and thermal conductance and the chemical composition of the composites has been studied. The results show that with the increase of the nickel content, the electric and thermal conductance of the composites varies. It is proposed that in the submicron structured composites, electrons and phonons have different transport mechanisms. The electric transport in the submicron-structured composites can be attributed to the medium punch-through effect and quantum tunnel punch-through effect of electrons and the low thermal conductance is due to the phonic scattering by the submicron-sized pores, grains and grain boundaries. The reason can also be used to explain why the thermal percolation threshold value lags behind the electric percolation value. The phenomenon has been observed.

  17. Lightweight cordierite–mullite refractories with low coefficients of thermal conductivity and high mechanical properties

    Indian Academy of Sciences (India)

    Wen Yan; Junfeng Chen; Nan Li; BingqiangHan Han; Yaowu Wei

    2015-04-01

    Lightweight cordierite–mullite refractories with low coefficients of thermal conductivity (CTCs), high strengths and high thermal-shock resistances were prepared using porous cordierite ceramics as aggregates. Phase compositions and microstructures of lightweight refractories were measured by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), etc. The effect of the relative mullite content of matrix (RMCM) on the microstructures and properties of lightweight refractories was investigated. It was found that the RMCM has a strong effect on the CTC and the mechanical properties. With an increase of RMCM, the compressive and flexural strengths of specimen increase. The thermal-shock resistance is the highest when the RMCM is 22 wt%, and also improved slightly when the RMCM is 46 wt% comparing with the specimen without mullite. When the RMCM is 46 wt%, the CTC reaches the minimum. Specimen with the RMCM of 46 wt% is the most appropriate mode, which has a moderate apparent porosity of 30%, a high compressive strength of 135.1 MPa, a high flexural strength of 20.5 MPa, a good thermal-shock resistance and a low CTC of 0.61 W mK−1.

  18. Is phenotypic plasticity a key mechanism for responding to thermal stress in ants?

    Science.gov (United States)

    Oms, Cristela Sánchez; Cerdá, Xim; Boulay, Raphaël

    2017-06-01

    Unlike natural selection, phenotypic plasticity allows organisms to respond quickly to changing environmental conditions. However, plasticity may not always be adaptive. In insects, body size and other morphological measurements have been shown to decrease as temperature increases. This relationship may lead to a physiological conflict in ants, where larger body size and longer legs often confer better thermal resistance. Here, we tested the effect of developmental temperature (20, 24, 28 or 32 °C) on adult thermal resistance in the thermophilic ant species Aphaenogaster senilis. We found that no larval development occurred at 20 °C. However, at higher temperatures, developmental speed increased as expected and smaller adults were produced. In thermal resistance tests, we found that ants reared at 28 and 32 °C had half-lethal temperatures that were 2 °C higher than those of ants reared at 24 °C. Thus, although ants reared at higher temperatures were smaller in size, they were nonetheless more thermoresistant. These results show that A. senilis can exploit phenotypic plasticity to quickly adjust its thermal resistance to local conditions and that this process is independent of morphological adaptations. This mechanism may be particularly relevant given current rapid climate warming.

  19. Thermal optimality of net ecosystem exchange of carbon dioxide and underlying mechanisms.

    Science.gov (United States)

    Niu, Shuli; Luo, Yiqi; Fei, Shenfeng; Yuan, Wenping; Schimel, David; Law, Beverly E; Ammann, Christof; Arain, M Altaf; Arneth, Almut; Aubinet, Marc; Barr, Alan; Beringer, Jason; Bernhofer, Christian; Black, T Andrew; Buchmann, Nina; Cescatti, Alessandro; Chen, Jiquan; Davis, Kenneth J; Dellwik, Ebba; Desai, Ankur R; Etzold, Sophia; Francois, Louis; Gianelle, Damiano; Gielen, Bert; Goldstein, Allen; Groenendijk, Margriet; Gu, Lianhong; Hanan, Niall; Helfter, Carole; Hirano, Takashi; Hollinger, David Y; Jones, Mike B; Kiely, Gerard; Kolb, Thomas E; Kutsch, Werner L; Lafleur, Peter; Lawrence, David M; Li, Linghao; Lindroth, Anders; Litvak, Marcy; Loustau, Denis; Lund, Magnus; Marek, Michal; Martin, Timothy A; Matteucci, Giorgio; Migliavacca, Mirco; Montagnani, Leonardo; Moors, Eddy; Munger, J William; Noormets, Asko; Oechel, Walter; Olejnik, Janusz; Kyaw Tha Paw U; Pilegaard, Kim; Rambal, Serge; Raschi, Antonio; Scott, Russell L; Seufert, Günther; Spano, Donatella; Stoy, Paul; Sutton, Mark A; Varlagin, Andrej; Vesala, Timo; Weng, Ensheng; Wohlfahrt, Georg; Yang, Bai; Zhang, Zhongda; Zhou, Xuhui

    2012-05-01

    • It is well established that individual organisms can acclimate and adapt to temperature to optimize their functioning. However, thermal optimization of ecosystems, as an assemblage of organisms, has not been examined at broad spatial and temporal scales. • Here, we compiled data from 169 globally distributed sites of eddy covariance and quantified the temperature response functions of net ecosystem exchange (NEE), an ecosystem-level property, to determine whether NEE shows thermal optimality and to explore the underlying mechanisms. • We found that the temperature response of NEE followed a peak curve, with the optimum temperature (corresponding to the maximum magnitude of NEE) being positively correlated with annual mean temperature over years and across sites. Shifts of the optimum temperature of NEE were mostly a result of temperature acclimation of gross primary productivity (upward shift of optimum temperature) rather than changes in the temperature sensitivity of ecosystem respiration. • Ecosystem-level thermal optimality is a newly revealed ecosystem property, presumably reflecting associated evolutionary adaptation of organisms within ecosystems, and has the potential to significantly regulate ecosystem-climate change feedbacks. The thermal optimality of NEE has implications for understanding fundamental properties of ecosystems in changing environments and benchmarking global models.

  20. Mechanical and thermal buckling analysis of sandwich panels under different edge conditions

    Science.gov (United States)

    Ko, William L.

    1993-01-01

    By using the Rayleigh-Ritz method of minimizing the total potential energy of a structural system, combined load (mechanical or thermal load) buckling equations are established for orthotropic rectangular sandwich panels supported under four different edge conditions. Two-dimensional buckling interaction curves and three dimensional buckling interaction surfaces are constructed for high-temperature honeycomb-core sandwich panels supported under four different edge conditions. The interaction surfaces provide easy comparison of the panel buckling strengths and the domains of symmetrical and antisymmetrical buckling associated with the different edge conditions. Thermal buckling curves of the sandwich panels also are presented. The thermal buckling conditions for the cases with and without thermal moments were found to be identical for the small deformation theory. In sandwich panels, the effect of transverse shear is quite large, and by neglecting the transverse shear effect, the buckling loads could be overpredicted considerably. Clamping of the edges could greatly increase buckling strength more in compression than in shear.

  1. Investigation of mechanical properties of thermal coatings obtained during plasma spraying of powder zirconium dioxide

    Science.gov (United States)

    Ibragimov, A. R.; Ilinkova, T. A.; Shafigullin, L. N.; Saifutdinov, A. I.

    2017-01-01

    Thermal coatings of zirconia partially stabilized with yttrium, deposited by low-temperature plasma, are the basis for the thermal protection of aircraft engine. At the same time there is an actual problem of selection of coating systems “ceramic layer - underlayer” of great thickness, providing better thermal protection, but having low strength characteristics due to the accumulation of internal stresses. To determine the optimal thickness of the test method used in the 4-point bending to allow the surface coating to explore in the elastic-plastic behavior of the field of coatings and strength. Based on the experimental results established the role of underlayer in the formation of the complex mechanical properties of thermal barrier coatings. With a well formed underlayer (PVNH16U6) system becomes sensitive to a change in thickness of the coating, to optimize the response on the strength and deformation criteria. According to the results the optimum ratio of the thickness of the ceramic layer and the underlayer should be regarded as the ratio of 3-5 for which the highest strength values were obtained for all the test coating systems.

  2. Stress Analysis and Failure Mechanisms of Plasma-Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Yang, Jiasheng; Wang, Liang; Li, Dachuan; Zhong, Xinghua; Zhao, Huayu; Tao, Shunyan

    2017-06-01

    Yttria-stabilized zirconia coatings were deposited by plasma spraying and heat-treated at 1100 °C for 50, 100, 150, and 200 h in air, respectively. Mechanical properties including microhardness and Young's modulus were evaluated using the nanoindentation test. Residual stresses in the ceramic topcoat and the thermally grown oxide (TGO) layer were measured using Raman spectroscopy and photoluminescence piezo-spectroscopy (PLPS) techniques, respectively. The results showed that both the modulus and hardness increased with the thermal exposure time up to 100 h and then gradually decreased. The accumulated tensile stress in the as-sprayed topcoat changed to compressive stress after thermal exposure, and the compressive stress in the topcoat increased with an increase of thermal exposure time up to 150 h. The average compressive stresses in the TGO layer were higher than that of the cross-sectional topcoat, and the measured in-plane compressive stress increased firstly and then gradually decreased with increasing exposure time. The local interface geometry strongly affect the nature and evolution of hydrostatic stresses in the TGO. Finally, the crack initiation and propagation at the topcoat/TGO/bondcoat interface has been discussed with respect to the residual stresses in the plasma-sprayed TBC system.

  3. Influence of Thermal Shock on the Mechanical Behavior of Si-SiC Coated Carbon/Carbon Composites

    Institute of Scientific and Technical Information of China (English)

    Qiangang Fu; Hejun Li; Yongjie Wang; Kezhi Li; Lu Wei

    2009-01-01

    Si-SiC coating was prepared on the surface of carbon/carbon (C/C) composites by a two-step technique of pack cementation, and the influences of thermal shock between 1773 K and room temperature in air on the mechanical property and fracture behavior of the coated C/C were studied. The results show that, after thermal shock between 1773 K and room temperature for 5, 10 and 15 times, the flexural strength of coated composites increases by 4.29%, 15.00% and 24.20%, respectively. The toughness of the coated C/C enhances gradually during the thermal shock test. The improvement of the mechanical property after the thermal shock test is primarily caused by the weakening of the fiber-matrix interface and the reduction of residual thermal stresses by thermal shock.

  4. Thermal Mechanical Processing Effects on Microstructure Evolution and Mechanical Properties of the Sintered Ti-22Al-25Nb Alloy.

    Science.gov (United States)

    Wang, Yuanxin; Lu, Zhen; Zhang, Kaifeng; Zhang, Dalin

    2016-03-11

    This work illustrates the effect of thermal mechanical processing parameters on the microstructure and mechanical properties of the Ti-22Al-25Nb alloy prepared by reactive sintering with element powders, consisting of O, B2 and Ti₃Al phases. Tensile and plane strain fracture toughness tests were carried out at room temperature to understand the mechanical behavior of the alloys and its correlation with the microstructural features characterized by scanning and transmission electron microscopy. The results show that the increased tensile strength (from 340 to 500 MPa) and elongation (from 3.6% to 4.2%) is due to the presence of lamellar O/B2 colony and needle-like O phase in B2 matrix in the as-processed Ti-22Al-25Nb alloys, as compared to the coarse lath O adjacent to B2 in the sintered alloys. Changes in morphologies of O phase improve the fracture toughness (KIC) of the sintered alloys from 7 to 15 MPa·m(-1/2). Additionally, the fracture mechanism shifts from cleavage fracture in the as-sintered alloys to quasi-cleavage fracture in the as-processed alloys.

  5. Thermal Mechanical Processing Effects on Microstructure Evolution and Mechanical Properties of the Sintered Ti-22Al-25Nb Alloy

    Directory of Open Access Journals (Sweden)

    Yuanxin Wang

    2016-03-01

    Full Text Available This work illustrates the effect of thermal mechanical processing parameters on the microstructure and mechanical properties of the Ti-22Al-25Nb alloy prepared by reactive sintering with element powders, consisting of O, B2 and Ti3Al phases. Tensile and plane strain fracture toughness tests were carried out at room temperature to understand the mechanical behavior of the alloys and its correlation with the microstructural features characterized by scanning and transmission electron microscopy. The results show that the increased tensile strength (from 340 to 500 MPa and elongation (from 3.6% to 4.2% is due to the presence of lamellar O/B2 colony and needle-like O phase in B2 matrix in the as-processed Ti-22Al-25Nb alloys, as compared to the coarse lath O adjacent to B2 in the sintered alloys. Changes in morphologies of O phase improve the fracture toughness (KIC of the sintered alloys from 7 to 15 MPa·m−1/2. Additionally, the fracture mechanism shifts from cleavage fracture in the as-sintered alloys to quasi-cleavage fracture in the as-processed alloys.

  6. Mechanical synthesis of copper-carbon nanocomposites: Structural changes, strengthening and thermal stabilization

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, D., E-mail: daniela.nunes@ist.utl.pt [Associacao Euratom/IST, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); LNEG, Estrada do Paco do Lumiar, 1649-038 Lisboa (Portugal); ICEMS, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Livramento, V. [Associacao Euratom/IST, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); LNEG, Estrada do Paco do Lumiar, 1649-038 Lisboa (Portugal); Mateus, R. [Associacao Euratom/IST, Instituto de Plasmas e Fusao Nuclear - Laboratorio Associado, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Correia, J.B. [LNEG, Estrada do Paco do Lumiar, 1649-038 Lisboa (Portugal); Alves, L.C. [ITN, Instituto Tecnologico e Nuclear, Estrada Nacional 10, 2686-953 Sacavem (Portugal); Vilarigues, M. [Departamento de Conservacao e Restauro e R and D Unit Vidro e da Ceramica Para as Artes, FCT-UNL, Quinta da Torre, 2829-516 Caparica (Portugal); Carvalho, P.A. [ICEMS, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Departamento de Bioengenharia, Instituto Superior Tecnico, Av. Rovisco Pais, 1049-001 Lisboa (Portugal)

    2011-11-15

    Highlights: {yields} The study characterized Cu-nanodiamond (Cu-nD) and Cu-graphite (Cu-G) composites. {yields} Preservation of nD crystalline structure during high-energy milling was demonstrated. {yields} Higher refinement of matrix in Cu-nD comparing to Cu-G is due to a milling mechanism. {yields} Remarkable thermal stability and microhardness have been achieved in Cu-nD and Cu-G. {yields} Strengthening resulted mainly from grain refinement and second-phase reinforcement. - Abstract: Processing of copper-carbon nanocomposites by mechanical synthesis poses specific challenges as carbon phases are prone to amorphization and exhibit an intrinsically difficult bonding with copper. The present work investigates Cu-nanodiamond (Cu-nD) and Cu-graphite (Cu-G) composites produced by mechanical synthesis and subsequent heat treatments. Transmission electron microscopy observations showed homogeneous particle distributions and intimate bonding between the metallic matrix and the carbon phases. Ring diffraction patterns of chemically extracted carbon phases demonstrated that milled nanodiamond preserved crystallinity, while an essentially amorphous nature could be inferred for milled graphite. Raman spectra confirmed that nanodiamond particles remained essentially unaffected by the mechanical synthesis, whereas the bands of milled graphite were significantly changed into the typical amorphous carbon fingerprint. Particle-induced X-ray emission spectroscopy showed that the total contamination originating from the milling media remained below 0.7 wt.%. The Cu-nanodiamond composite exhibited remarkable microhardness and microstructural thermal stability when compared with pure nanostructured copper.

  7. Effects of Inorganic Fillers on the Thermal and Mechanical Properties of Poly(lactic acid

    Directory of Open Access Journals (Sweden)

    Xingxun Liu

    2014-01-01

    Full Text Available Addition of filler to polylactic acid (PLA may affect its crystallization behavior and mechanical properties. The effects of talc and hydroxyapatite (HA on the thermal and mechanical properties of two types of PLA (one amorphous and one semicrystalline have been investigated. The composites were prepared by melt blending followed by injection molding. The molecular weight, morphology, mechanical properties, and thermal properties have been characterized by gel permeation chromatography (GPC, scanning electron microscope (SEM, instron tensile tester, thermogravimetric analysis (TGA, differential scanning calorimetry (DSC, and dynamic mechanical analysis (DMA. It was found that the melting blending led to homogeneous distribution of the inorganic filler within the PLA matrix but decreased the molecular weight of PLA. Regarding the filler, addition of talc increased the crystallinity of PLA, but HA decreased the crystallinity of PLA. The tensile strength of the composites depended on the crystallinity of PLA and the interfacial properties between PLA and the filler, but both talc and HA filler increased the toughness of PLA.

  8. Mechanism of Thermal Reversal of the (Fulvalene)tetracarbonyldiruthenium Photoisomerization: Toward Molecular Solar-Thermal Energy Storage

    Energy Technology Data Exchange (ETDEWEB)

    Kanai, Y; Srinivasan, V; Meier, S K; Vollhardt, K P; Grossman, J C

    2010-02-18

    In the currently intensifying quest to harness solar energy for the powering of our planet, most efforts are centered around photoinduced generic charge separation, such as in photovoltaics, water splitting, other small molecule activation, and biologically inspired photosynthetic systems. In contrast, direct collection of heat from sunlight has received much less diversified attention, its bulk devoted to the development of concentrating solar thermal power plants, in which mirrors are used to focus the sun beam on an appropriate heat transfer material. An attractive alternative strategy would be to trap solar energy in the form of chemical bonds, ideally through the photoconversion of a suitable molecule to a higher energy isomer, which, in turn, would release the stored energy by thermal reversal. Such a system would encompass the essential elements of a rechargeable heat battery, with its inherent advantages of storage, transportability, and use on demand. The underlying concept has been explored extensively with organic molecules (such as the norbornadiene-quadricyclane cycle), often in the context of developing photoswitches. On the other hand, organometallic complexes have remained relatively obscure in this capacity, despite a number of advantages, including expanded structural tunability and generally favorable electronic absorption regimes. A highly promising organometallic system is the previously reported, robust photo-thermal fulvalene (Fv) diruthenium couple 1 {l_reversible} 2 (Scheme 1). However, although reversible and moderately efficient, lack of a full, detailed atom-scale understanding of its key conversion and storage mechanisms have limited our ability to improve on its performance or identify optimal variants, such as substituents on the Fv, ligands other than CO, and alternative metals. Here we present a theoretical investigation, in conjunction with corroborating experiments, of the mechanism for the heat releasing step of 2 {yields} 1 and

  9. Curing Mechanism of Condensed Polynuclear Aromatic Resin and Thermal Stability of Cured Resin

    Institute of Scientific and Technical Information of China (English)

    Li Shibin; Sun Qiqian; Wang Yuwei; Wu Mingbo; Zhang Zailong

    2015-01-01

    In order to improve the thermal stability of condensed polynuclear aromatic (COPNA) resin synthesized from vacuum residue, 1,4-benzenedimethanol was added to cure COPNA resin. The curing mechanism was investigated by pro-ton nuclear magnetic resonance spectrometry, solid carbon-13 nuclear magnetic resonance spectrometry and Fourier trans-form infrared spectroscopy. Microstructures of the uncured and the cured COPNA resins were studied by scanning electron microscopy and X-ray diffractometry. The thermal stability of COPNA resins before and after curing was tested by thermo-gravimetric analysis. The element composition of the cured COPNA resin heated at different temperatures was analyzed by an element analyzer. The results showed that the uncured COPNA resin reacted with the cross-linking agent during the cur-ing process, and the curing mechanism was conifrmed to be the electrophilic substitution reaction. Compared with the un-cured COPNA resin, the cured COPNA resin had a smooth surface, well-ordered and streamlined sheet structure with more crystalline solids, better molecular arrangement and orientation. The weight loss process of the uncured and cured COPNA resins was divided into three stages. Carbon residue of the cured COPNA resin was 41.65%at 600℃, which was much higher than 25.02%of the uncured COPNA resin, which indicated that the cured COPNA resin had higher thermal stability.

  10. Numerical modelling of levee stability based on coupled mechanical, thermal and hydrogeological processes

    Directory of Open Access Journals (Sweden)

    Dwornik Maciej

    2016-01-01

    Full Text Available The numerical modelling of coupled mechanical, thermal and hydrogeological processes for a soil levee is presented in the paper. The modelling was performed for a real levee that was built in Poland as a part of the ISMOP project. Only four parameters were changed to build different flood waves: the water level, period of water increase, period of water decrease, and period of low water level after the experiment. Results of numerical modelling shows that it is possible and advisable to calculate simultaneously changes of thermal and hydro-mechanical fields. The presented results show that it is also possible to use thermal sensors in place of more expensive pore pressure sensors, with some limitations. The results of stability analysis show that the levee is less stable when the water level decreases, after which factor of safety decreases significantly. For all flooding wave parameters described in the paper, the levee is very stable and factor of safety variations for any particular stage were not very large.

  11. Improvements of Thermal, Mechanical, and Water-Resistance Properties of Polybenzoxazine/Boron Carbide Nanocomposites

    Science.gov (United States)

    Ramdani, Noureddine; Derradji, Mehdi; Wang, Jun; Mokhnache, El-Oualid; Liu, Wen-Bin

    2016-09-01

    Novel kinds of nanocomposites based on bisphenol A-aniline based polybenzoxazine matrix P(BA-a) and 0 wt.%-20 wt.% boron carbide (B4C) nanoparticles were produced and their properties were evaluated in terms of the nano-B4C content. The thermal conductivity of the P(BA-a) matrix was improved approximately three times from 0.18 W/m K to 0.86 W/m K at 20 wt.% nano-B4C loading, while its coefficient of thermal expansion (CTE) was deceased by 47% with the same nanofiller content. The microhardness properties were significantly improved by adding the B4C nanoparticles. At 20 wt.% of nano-B4C content, dynamic mechanical analysis (DMA) revealed a marked increase in the storage modulus and the glass transition temperature ( T g) of the nanocomposites, reaching 3.9 GPa and 204°C, respectively. Hot water uptake tests showed that the water-resistance of the polybenzoxazine matrix was increased by filling with nano-B4C nano-filler. The morphological analysis reflected that the improvements obtained in the mechanical and thermal properties are related to the uniform dispersion of the nano-B4C particles and their strong adhesion to the P(BA-a) matrix.

  12. Thermal and Mechanical Properties of Poly-Dicyclopentadiene (DCPD) at Cryogenic Temperatures

    Science.gov (United States)

    Toplosky, V. J.; Walsh, R. P.

    2006-03-01

    Poly-diCylopentadiene (poly-DCPD) resins are widely used because of their excellent physical and mechanical properties and their compatibility with various molding techniques. Poly-DCPD's ability to be rotationally molded has generated the potential for this crosslinked thermoset polymer to be used for cryogenic tanks. In turn, this has generated the need for cryogenic materials property data on these resins. In a collaborative research agreement between the National High Magnetic Field Laboratory (NHMFL) and Cymetech LLC, five different variations of poly-DCPD have been thermally and mechanically characterized. Specifically, the tensile, compressive, shear and flexural properties have been measured at 77 K, as well as thermal contraction to 77 and 4 K. There are subtle differences in the properties between each formulation and larger discrepancies when compared to cryogenic data for other polymers. The thermal contraction to 77 K and elastic modulus are typical compared to other epoxies and polyester while the 77 K strength and elongation to failure are superior. The high strengths and elongations are good indicators that poly-DCPD also has good toughness — an important property in many low temperature applications. This initial cryogenic properties database for poly-DCPD allows it to be considered as a neat polymer in cryogenic applications, as well as an excellent matrix material for fiber reinforced composites in cryogenic applications.

  13. Reduced silanized graphene oxide/epoxy-polyurethane composites with enhanced thermal and mechanical properties

    Science.gov (United States)

    Lin, Jing; Zhang, Peipei; Zheng, Cheng; Wu, Xu; Mao, Taoyan; Zhu, Mingning; Wang, Huaquan; Feng, Danyan; Qian, Shuxuan; Cai, Xianfang

    2014-10-01

    This paper describes the synthesis of reduced silanized graphene oxide/epoxy-polyurethane (EPUAs/R-Si-GEO) composites with enhanced thermal and mechanical properties. Graphene oxide (GEO), prepared from natural graphite flakes, was modified with methacryloxypropyltrimethoxysilane to prepare silanized GEO (Si-GEO), and was then reduced by NaHSO3 to prepare R-Si-GEO (partially reduced Si-GEO). EPAc/R-Si-GEO (R-Si-GEO/epoxy acrylate copolymers) was synthesized via an in situ polymerization of R-Si-GEO and epoxy acrylic monomers. EPUAs/R-Si-GEO was obtained by curing reaction between EPAc/R-Si-GEO and an isocyanate curing agent. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) were used to characterize the surface and crystal structure of the modified graphene and EPUAs/R-Si-GEO. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize their morphology. Thermal gravimetric analysis (TGA), tensile strength, elongation at break, and cross-linking density measurements showed that the thermal stability and mechanical properties of EPUAs/R-Si-GEO were greatly enhanced by the addition of R-Si-GEO.

  14. Mesoscale thermal-mechanical analysis of shocked induced granular explosives and polymer-bonded explosives

    Science.gov (United States)

    Wang, Xinjie; Wu, Yanqing; Huang, Fenglei

    2015-06-01

    The thermal-mechanical response of HMX-based granular explosives (GXs) and polymer-bonded explosives (PBXs) with variable number of crystals from 10 to 100 under impact loading is investigated with finite element software ABAQUS. A series of three dimensional mesoscale calculations are carried out with the crystal plasticity constitutive model for HMX crystals that accounts for nonlinear elasticity and crystalline plasticity and the viscoelastic model for the polymer binder. To make the analysis comparable, the morphology and the size of HMX crystals are kept the same for both GXs and PBXs. In order to quantify the effect of polymer binder under different strain rate, the calculation models are impacted with initial boundary velocities from 10 to 100 m/s. The results shows that the average pressure of PBXs is approximately 50% higher than GXs and that the localized stress and temperature is highly increased with the polymer binder, which indicates the crystal anisotropy as well as the polymer binder plays an important role in influencing the stress and thermal response of HMX crystals. The thermal-mechanical response analyzed here is essential to predict the formation of hot spot and the ignition of explosives.

  15. Mechanisms of thermally induced threshold voltage instability in GaN-based heterojunction transistors

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shu; Liu, Shenghou; Liu, Cheng; Lu, Yunyou; Chen, Kevin J., E-mail: eekjchen@ust.hk [Department of Electronic and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2014-12-01

    In this work, we attempt to reveal the underlying mechanisms of divergent V{sub TH}-thermal-stabilities in III-nitride metal-insulator-semiconductor high-electron-mobility transistor (MIS-HEMT) and MOS-Channel-HEMT (MOSC-HEMT). In marked contrast to MOSC-HEMT featuring temperature-independent V{sub TH}, MIS-HEMT with the same high-quality gate-dielectric/III-nitride interface and similar interface trap distribution exhibits manifest thermally induced V{sub TH} shift. The temperature-dependent V{sub TH} of MIS-HEMT is attributed to the polarized III-nitride barrier layer, which spatially separates the critical gate-dielectric/III-nitride interface from the channel and allows “deeper” interface trap levels emerging above the Fermi level at pinch-off. This model is further experimentally validated by distinct V{sub G}-driven Fermi level movements at the critical interfaces in MIS-HEMT and MOSC-HEMT. The mechanisms of polarized III-nitride barrier layer in influencing V{sub TH}-thermal-stability provide guidelines for the optimization of insulated-gate III-nitride power switching devices.

  16. Influence of thermal aging on microstructure and mechanical properties of CLAM steel

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Lixin, E-mail: lxhuang@ysu.edu.cn [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Hu, Xue; Yang, Chunguang; Yan, Wei [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Xiao, Furen [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Shan, Yiyin, E-mail: yyshan@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Yang, Ke [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2013-11-15

    In order to investigate the influence of thermal aging on microstructure and mechanical properties of CLAM (China low activation martensitic) steel, a comparison study was made on the as-tempered and the aged steels. The tempered CLAM steels were subjected to aging treatment at 600 °C for 1100 h and 3000 h, and at 650 °C for 1100 h, respectively. The changes of microstructure were characterized by both transmission electron microscope (TEM) and scanning electron microscope (SEM). The mechanical properties were evaluated by Charpy impact, tensile and Vickers hardness tests. The upper shelf energy (USE) of the thermal aged CLAM steel decreased with the extension of aging time, while the yield strength changed slightly. After long-term thermal aging, the MX type precipitates remained stable. The coarsening of M{sub 23}C{sub 6} and the formation of Laves phase were confirmed by scanning/transmission electron microscopes. The Laves phase was the main factor leading to the increase of DBTT.

  17. Influence of thermal aging on microstructure and mechanical properties of CLAM steel

    Science.gov (United States)

    Huang, Lixin; Hu, Xue; Yang, Chunguang; Yan, Wei; Xiao, Furen; Shan, Yiyin; Yang, Ke

    2013-11-01

    In order to investigate the influence of thermal aging on microstructure and mechanical properties of CLAM (China low activation martensitic) steel, a comparison study was made on the as-tempered and the aged steels. The tempered CLAM steels were subjected to aging treatment at 600 °C for 1100 h and 3000 h, and at 650 °C for 1100 h, respectively. The changes of microstructure were characterized by both transmission electron microscope (TEM) and scanning electron microscope (SEM). The mechanical properties were evaluated by Charpy impact, tensile and Vickers hardness tests. The upper shelf energy (USE) of the thermal aged CLAM steel decreased with the extension of aging time, while the yield strength changed slightly. After long-term thermal aging, the MX type precipitates remained stable. The coarsening of M23C6 and the formation of Laves phase were confirmed by scanning/transmission electron microscopes. The Laves phase was the main factor leading to the increase of DBTT.

  18. Numerical Simulation Procedure for Modeling TGO Crack Propagation and TGO Growth in Thermal Barrier Coatings upon Thermal-Mechanical Cycling

    Directory of Open Access Journals (Sweden)

    Ding Jun

    2014-01-01

    Full Text Available This paper reports a numerical simulation procedure to model crack propagation in TGO layer and TGO growth near a surface groove in metal substrate upon multiple thermal-mechanical cycles. The material property change method is employed to model TGO formation cycle by cycle, and the creep properties for constituent materials are also incorporated. Two columns of repeated nodes are placed along the interface of the potential crack, and these nodes are bonded together as one node at a geometrical location. In terms of critical crack opening displacement criterion, onset of crack propagation in TGO layer has been determined by finite element analyses in comparison with that without predefined crack. Then, according to the results from the previous analyses, the input values for the critical failure parameters for the subsequent analyses can be decided. The robust capabilities of restart analysis in ABAQUS help to implement the overall simulation for TGO crack propagation. The comparison of the TGO final deformation profile between numerical and experimental observation shows a good agreement indicating the correctness and effectiveness of the present procedure, which can guide the prediction of the failure in TGO for the future design and optimization for TBC system.

  19. Pharmacological activation of 5-HT7 receptors reduces nerve injury-induced mechanical and thermal hypersensitivity.

    Science.gov (United States)

    Brenchat, Alex; Nadal, Xavier; Romero, Luz; Ovalle, Sergio; Muro, Asunción; Sánchez-Arroyos, Ricard; Portillo-Salido, Enrique; Pujol, Marta; Montero, Ana; Codony, Xavier; Burgueño, Javier; Zamanillo, Daniel; Hamon, Michel; Maldonado, Rafael; Vela, José Miguel

    2010-06-01

    The involvement of the 5-HT(7) receptor in nociception and pain, particularly chronic pain (i.e., neuropathic pain), has been poorly investigated. In the present study, we examined whether the 5-HT(7) receptor participates in some modulatory control of nerve injury-evoked mechanical hypersensitivity and thermal (heat) hyperalgesia in mice. Activation of 5-HT(7) receptors by systemic administration of the selective 5-HT(7) receptor agonist AS-19 (1 and 10mg/kg) exerted a clear-cut reduction of mechanical and thermal hypersensitivities that were reversed by co-administering the selective 5-HT(7) receptor antagonist SB-258719. Interestingly, blocking of 5-HT(7) receptors with SB-258719 (2.5 and 10mg/kg) enhanced mechanical (but not thermal) hypersensitivity in nerve-injured mice and induced mechanical hypersensitivity in sham-operated mice. Effectiveness of the treatment with a 5-HT(7) receptor agonist was maintained after repeated systemic administration: no tolerance to the antiallodynic and antihyperalgesic effects was developed following treatment with the selective 5-HT(7) receptor agonist E-57431 (10mg/kg) twice daily for 11 days. The 5-HT(7) receptor co-localized with GABAergic cells in the dorsal horn of the spinal cord, suggesting that the activation of spinal inhibitory GABAergic interneurons could contribute to the analgesic effects of 5-HT(7) receptor agonists. In addition, a significant increase of 5-HT(7) receptors was found by immunohistochemistry in the ipsilateral dorsal horn of the spinal cord after nerve injury, suggesting a "pain"-triggered regulation of receptor expression. These results support the idea that the 5-HT(7) receptor subtype is involved in the control of pain and point to a new potential use of 5-HT(7) receptor agonists for the treatment of neuropathic pain.

  20. Tribological, Thermal, and Kinetic Characterization of 300-mm Copper Chemical Mechanical Planarization Process

    Science.gov (United States)

    Jiao, Yubo; Adi Sampurno, Yasa; Zhuang, Yun; Wei, Xiaomin; Meled, Anand; Philipossian, Ara

    2011-05-01

    In this study, the tribological, thermal, and kinetic attributes of 300-mm copper chemical mechanical planarization were characterized for two different pads. The coefficient of friction (COF) ranged from 0.39 to 0.59 for the D100 pad, indicating that boundary lubrication was the dominant tribological mechanism. In comparison, COF decreased sharply from 0.55 to 0.03 for the IC1000 pad, indicating that the tribological mechanism transitioned rapidly from boundary lubrication to partial lubrication. Consequently, the D100 pad exhibited higher pad temperatures and removal rates than the IC1000 pad. A two-step modified Langmuir-Hinshelwood model was used to simulate copper removal rates as well as chemical and mechanical rate constants. The simulated copper removal rates agreed very well with experimental data and the model successfully captured the non-Prestonian behavior. The simulated chemical rate to mechanical rate constant ratios indicated that the IC1000 pad generally produced a more mechanically controlled removal mechanism than the D100 pad.

  1. Thermal-mechanical Properties of Epoxy-impregnated Bi-2212/Ag Composite

    Energy Technology Data Exchange (ETDEWEB)

    Li, Pei [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Wang, Yang [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Godeke, Arno [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Ye, Liyang [North Carolina State Univ., Raleigh, NC (United States); Flanagan, Gene [Muons Inc., Batavia, IL (United States); Shen, Tengming [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)

    2014-11-26

    Knowledge of the thermal-mechanical properties of epoxy/superconductor/insulation composite is important for designing, fabricating, and operating epoxy impregnated high field superconducting magnets near their ultimate potentials. We report measurements of the modulus of elasticity, Poisson’s ratio, and the coefficient of thermal contraction of epoxy-impregnated composite made from the state-of-the-art powder-in-tube multifilamentary Ag/Bi2Sr2CaCu2Ox round wire at room temperature and cryogenic temperatures. Stress-strain curves of samples made from single-strand and Rutherford cables were tested under both monotonic and cyclic compressive loads, with single strands insulated using a thin TiO2 insulation coating and the Rutherford cable insulated with a braided ceramic sleeve.

  2. [Mechanism of action and efficacy of litium chloride in thermal ischemia of the kidney].

    Science.gov (United States)

    Kazachenko, A V; Dzeranov, N K; Plotnikov, E Iu; Golovanov, S A; Zorov, D B; Kirpatovskiĭ, V I

    2009-01-01

    A protective effect of lithium chloride (LC) in thermal ischemia of the kidney of different duration was studied in rats. LC efficacy was estimated by functional activity of ischemic kidney in early and late reperfusion period, by damage to mitochondria of tubular epithelial cells and production of active oxygen forms (AOF) and nitric oxide (NO). LC has a marked anti-ischemic effect. In thermal renal ischemia for 40 and 60 min LC provides functional safety of the ischemic organ. In longer ischemia, 50% of the animals died. The mechanism of the protective action of LC is related to reduction of APK production, support of a high transmembrane potential of mitochondria and NO synthesis redistribution in the cells of tubular epithelium cells.

  3. Mechanical, thermal, rheological and morphological behaviour of irradiated PP/HA composites

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, C. [Universidad de Oriente, Nucleo de Anzoategui, Escuela de Ingenieria y Ciencias Aplicadas, Depto de Ingenieria Quimica, Puerto la Cruz (Venezuela); Albano, C. [Centro de Quimica, Laboratorio de Polimeros, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020A (Venezuela) and Universidad Central de Venezuela, Facultad de Ingenieria, Escuela de Ingenieria Quimica, Caracas 1041A (Venezuela)]. E-mail: calbano@ivic.ve; Karam, A. [Centro de Quimica, Laboratorio de Polimeros, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020A (Venezuela)]. E-mail: akaram@quimica.ivic.ve; Dominguez, N. [Centro de Quimica, Laboratorio de Polimeros, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020A (Venezuela); Sanchez, Y. [Centro de Quimica, Laboratorio de Polimeros, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020A (Venezuela); Gonzalez, G. [Centro Tecnologico, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas 1020A (Venezuela)

    2005-07-01

    Hydroxyapatite (HA) reinforced polypropylene (PP) composites are being developed as bone graft materials. In this research, the effect of {gamma} irradiation on mechanical, rheological, thermal and morphological behaviour of PP-HA composites was studied. The melt flow index of polymer increased markedly when it was exposed to radiation. This is indicative of chain scission reaction as the predominant process. During the tensile testing, the composites exhibited brittle behaviour, showing no fluency point. Elongation at break showed a tendency to decrease with the increase in radiation dose while stress at break did not show significant variation with radiation dose. High HA content (>20%) and radiation dose (25 kGy) had significant influence on thermal stability.

  4. Uniaxial Negative Thermal Expansion and Mechanical Properties of a Zinc-Formate Framework

    Directory of Open Access Journals (Sweden)

    Hongqiang Gao

    2017-02-01

    Full Text Available The thermal expansion behavior of a metal-formate framework, Zn(HCOO2·2(H2O (1, has been systematically studied via variable temperature single-crystal X-ray diffraction. Our results demonstrate that this formate exhibits significant negative thermal expansion (NTE, −26(2 MK−1 along its c-axis. Detailed structural analyses reveal that the large NTE response is attributed to the ‘hinge-strut’ like framework motion. In addition, the fundamental mechanical properties of framework 1 have been explored via nanoindentation experiments. The measured elastic modulus and hardness properties on the (00-2/(100/(110 facets are 35.5/35.0/27.1 and 2.04/1.83/0.47 GPa, respectively. The stiffness and hardness anisotropy can be correlated well with the underlying framework structure, like its thermoelastic behavior.

  5. Continuum modeling of the mechanical and thermal behavior of discrete large structures

    Science.gov (United States)

    Nayfeh, A. H.; Hefzy, M. S.

    1980-01-01

    In the present paper we introduce a rather straightforward construction procedure in order to derive continuum equivalence of discrete truss-like repetitive structures. Once the actual structure is specified, the construction procedure can be outlined by the following three steps: (a) all sets of parallel members are identified, (b) unidirectional 'effective continuum' properties are derived for each of these sets and (c) orthogonal transformations are finally used to determine the contribution of each set to the 'overall effective continuum' properties of the structure. Here the properties includes mechanical (stiffnesses), thermal (coefficients of thermal expansions) and material densities. Once expanded descriptions of the steps (b) and (c) are done, the construction procedure will be applied to a wide variety of discrete structures and the results will be compared with those of other existing methods.

  6. Internal thermal origin mechanism of Karstic collapse column with no smoothly extrinsic cycle

    Institute of Scientific and Technical Information of China (English)

    LI Yong-jun; PENG Su-ping; LI Pei-quan; LIU Deng-xian; LIAN Hui-qing

    2008-01-01

    Huainan coal field as main object, investigation of Karstic hydrogeological conditions were developed in Huainan structureal unit, and the basic conditions, features and rules of Karstic growth were summarized. Geology background and causes of Karstic collapse columns were analyzed. Combined with ancient physiognomy, environment and litho-facies features. After studying synthetically Karstic collapse columns, shape of collapse body, filling feature, hydrodynamic condition and agglutinate material in Huainan area, considering mine hydrogeological conditions of Xuhuai coal field and referenced Karstic collapse columns characters of other mines in North China, the internal thermal origin theory is elementarily formed for Karstic collapse columns extrinsic cycle can not operate smoothly. Finaly, three aspects including distributing features of different kinds of Karstic collapse columns in north China type coal field, conditions of Karstic collapse columns origined from internal thermal with no smoothly extrinsic cycle, mechanics of causes were analyzed and demonstrated.

  7. Preparation by a Rheological Phase Reaction Method and Thermal Decomposition Reaction Mechanism of Nickelous Salicylate Tetrahydrate

    Institute of Scientific and Technical Information of China (English)

    Wang Jin-long; Yuan Liang-jie; Yang Yi-yong; Sun Ju-tang; Zhang Ke-li

    2003-01-01

    The single crystal nickel salicylate tetrahydrate was prepared with the rheological phase reaction method from nickelous hydroxide and salicylic acid. The crystal structure was determined. It is monoclinic, space group P21 /n, a =0.67874(3), b=0. 515 91(2), c=2. 313 30(9) nm, β=90.9286(17)°, V=0. 809 94(6) nm3, Z=2, ρcalcd =0. 065 0[I >2a(I)]. The thermal decomposition mechanism in an inert atmosphere was investigated via TG, DTG and DTA. The thermal decomposition products were characterized with IR and micro-powder X-ray diffraction method. A new coordination polymer (NiC6 H4O)n as an intermediate product and nanoscale metal nickel were obtained in the ranges of 364-429 ℃ and 429-680 ℃, respectively.

  8. Growth, optical, thermal and mechanical characterization of an organic crystal: Brucinium 5-sulfosalicylate trihydrate

    Indian Academy of Sciences (India)

    K Gayathri; P Krishnan; P R Rajkumar; G Anbalagan

    2014-12-01

    Single crystals of Brucinium 5-sulfosalicylate trihydrate (B5ST) were grown from ethanol–water (1:1) mixed solvent by the slow solvent evaporation method. X-ray powder diffraction analysis reveals that the crystal belongs to orthorhombic system with space group 212121. The various reflections were indexed and the lattice parameters were calculated. Photoluminescence (PL) shows peaks corresponding to protonation of the amino group. The optical absorption spectrum shows that the crystal has 90% transmittance in the visible region with a lower cut-off wavelength of 312 nm. Thermal analysis performed on the grown crystal indicates the thermal stability of the crystal and various thermodynamical parameters were calculated from the thermogravimetry (TG) data. The mechanical properties like Vickers microhardness number (v), stiffness constant (11) and yield strength (v) of the crystal were estimated by Vickers hardness test.

  9. Functionalized graphene nanoplatelets for enhanced mechanical and thermal properties of polyurethane nanocomposites

    Science.gov (United States)

    Yadav, Santosh Kumar; Cho, Jae Whan

    2013-02-01

    In the evolution of high performance graphene-based polymer nanocomposites, homogeneous dispersion of graphene nanoplatelets in the polymer matrix and exact interface control are difficult to achieve due to the potent interlayer cohesive energy and surface inactiveness of the nanocomposites. Herein, we present an effective way to fabricate high performance polyurethane (PU) nanocomposites via the incorporation of functionalized graphene nanoplatelets (f-GNP) during in situ polymerization. The f-GNP/PU nanocomposites exhibited a significant improvement in terms of their mechanical, thermal, and shape recovery properties. The modulus of the f-GNP/PU nanocomposites at 2 wt% graphene nanoplatelets loading is ten times greater than that of the pure PU sample. The breaking stress and shape recovery showed a highly improving trend with increasing wt% of f-GNP. An unprecedented enhancement of thermal stability at 30 °C compared to the pure PU is also found at 2 wt% loading of f-GNP via in situ polymerization.

  10. Analysis of the thermal fragmentation as a mechanism for the initiation of steam explosion

    Energy Technology Data Exchange (ETDEWEB)

    Lamome, J.; Meignen, R. [Institut de Radioprotection et de Surete Nucleaire, Dir. de la Surete de Reacteur, 92 - Fontenay aux Roses (France)

    2007-07-01

    We propose a theoretical study of the film behaviour and its stability during the phenomenon of drop thermal fragmentation. We discuss the role of the various possible influences on the film collapse and instability processes. First, we discuss the possibility of simple fuel/coolant contacts as a mechanism for the drop instability. Under this assumption, we then describe and test our model on Nelson and Duda explodability maps, with a particular emphasis on the description of the film evolution. The reasonable agreement obtained allows us to analyse the effect of various parameters as the ambient pressure, subcooling and trigger pulse shape on the film behaviour in Nelson and Duda experiments. The perspectives of this work are then shortly discussed including extrapolation to more prototypic situations and the role of thermal fragmentation itself. (authors)

  11. RESOLUTION STRATEGY FOR GEOMECHANICALLY-RELATED REPOSITORY DESIGN FOR THERMAL-MECHANICAL EFFECTS (RDTME)

    Energy Technology Data Exchange (ETDEWEB)

    M. Board

    2003-04-01

    In September of 2000, the U.S. Nuclear Regulatory Commission (NRC) issued an Issue Resolution Status Report (NRC 2000). The Key Technical Issue (KTI) agreements on Repository Design and Thermal-Mechanical Effects (RDTME) were jointly developed at the Technical Exchange and Management Meeting held on February 6-8, 2001 in Las Vegas, Nevada. In that report, a number of geomechanically-related issues were raised regarding the determination of rock properties, the estimation of the impacts of geologic variability, the use of numerical models, and the examination of drift degradation and design approach to the ground support system for the emplacement drifts. Ultimately, the primary end products of the KTI agreement resolution processes are an assessment of the preclosure stability of emplacement drifts and the associated ground support requirements. There is also an assessment of the postclosure degradation of the excavations when subjected to thermal and seismic-related stresses as well as in situ loading over time.

  12. Thermal and Mechanical Testing of Neoprene Gloves Used in a Space Shuttle Microgravity Glove Box Experiment

    Science.gov (United States)

    Wingard, Charles Doug; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    Neoprene gloves are used in a Space Shuttle Microgravity Glove Box (MGBX) experiment. In 1999, significant corrosion was observed in the work area and on the outer surface of the left glove ring. Analysis of the corrosion products showed that they contained chlorine. The Neoprene gloves used in this glove box were obtained in 1995, with a recommended shelf life of 3 years. After storage of these gloves in a cabinet drawer until 1999, significant signs of corrosion were also observed in the drawer. Mechanical and thermal properties were determined on samples cut from the finger and sleeve areas of the "good" and "bad" gloves. This data showed significant aging of the left-hand glove, particularly in the sleeve area. Thermal analysis data by DSC and TGA was complimentary to tensile data in showing this aging. However, this test data did not pinpoint the cause of the left-hand glove aging, or of the corrosion products.

  13. Effect of CNTs dispersion on the thermal and mechanical properties of Cu/CNTs nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Muhsan, Ali Samer, E-mail: alisameer2007@gmail.com, E-mail: faizahmad@petronas.com.my; Ahmad, Faiz, E-mail: alisameer2007@gmail.com, E-mail: faizahmad@petronas.com.my; Yusoff, Puteri Sri Melor Megat Bt, E-mail: puteris@petronas.com.my [Department of Mechanical Engineering, Universiti Teknologi PETRONAS (UTP) (Malaysia); Mohamed, Norani M., E-mail: noranimuti-mohamed@petronas.com.my [Centre of Innovative Nanostructures and Nanodevices (COINN), UTP (Malaysia); Raza, M. Rafi, E-mail: rafirazamalik@gmail.com [Universiti Kebangsaan Malaysia, 43600, Bangi, Selangor (Malaysia)

    2014-10-24

    Modified technique of metal injection molding (MIM) was used to fabricate multiwalled carbon nanotube (CNT) reinforced Cu nanocomposites. The effect of adding different amount of CNTs (0-10 vol.%) on the thermal and mechanical behaviour of the fabricated nanocomposites is presented. Scanning electron microscope analysis revealed homogenous dispersion of CNTs in Cu matrices at different CNTs contents. The experimentally measured thermal conductivities of Cu/CNTs nanocomposites showed extraordinary increase (76% higher than pure sintered Cu) with addition of 10 vol.% CNTs. As compared to the pure sintered Cu, increase in modulus of elasticity (Young's modulus) of Cu/CNTs nanocomposites sintered at 1050°C for 2.5 h was measured to be 48%. However, in case of 7.5 vol.% CNTs, Young's modulus was increased significantly about 51% compared to that of pure sintered Cu.

  14. Effect of Organoclay on Compatibilization, Thermal and Mechanical Properties of Polycarbonate/Polystyrene Blends

    CERN Document Server

    Singh, A K

    2014-01-01

    Pristine and organoclay modified polycarbonate/polystyrene (PC/PS) blends are prepared using melt-mixing technique. These blends are characterized for their morphology, structural, thermal and mechanical properties. Though our FTIR and XRD results show weak interactions between PC and PS phases, however, DSC and morphological study reveals that pristine PC/PS blends are immiscible. On other hand, introduction of organoclay results compatibilization of two polymer phases which is supported by significant shift in glass transition temperatures of the component phases and a distinct morphology having no phase segregation on sub-micron scale. Intercalation of polymers inside the clay gallery is achieved and is supported by XRD studies. A better thermal stability and higher value of modulus of the compatibilized blends compared to pristine PC/PS blends also support the reinforcement effect of organoclay to the PC/PS blend matrix.

  15. A Coupled Model of Multiphase Flow, Reactive Biogeochemical Transport, Thermal Transport and Geo-Mechanics.

    Science.gov (United States)

    Tsai, C. H.; Yeh, G. T.

    2015-12-01

    In this investigation, a coupled model of multiphase flow, reactive biogeochemical transport, thermal transport and geo-mechanics in subsurface media is presented. It iteratively solves the mass conservation equation for fluid flow, thermal transport equation for temperature, reactive biogeochemical transport equations for concentration distributions, and solid momentum equation for displacement with successive linearization algorithm. With species-based equations of state, density of a phase in the system is obtained by summing up concentrations of all species. This circumvents the problem of having to use empirical functions. Moreover, reaction rates of all species are incorporated in mass conservation equation for fluid flow. Formation enthalpy of all species is included in the law of energy conservation as a source-sink term. Finite element methods are used to discretize the governing equations. Numerical experiments are presented to examine the accuracy and robustness of the proposed model. The results demonstrate the feasibility and capability of present model in subsurface media.

  16. FAILURE MECHANISMS OF THERMAL BARRIER COATINGS INTERNAL COMBUSTION ENGINES AND llMPROVEMENTS

    Directory of Open Access Journals (Sweden)

    ADNAN PARLAK

    2003-04-01

    Full Text Available MechanicaJ properties of high performance ceramics have been improved to the point where their use in heat engines is possible. The high temperature strength and low thermal expansion properties of bigh performance ceramics offer an advantage over metals in the development of non-water cooling engine. However, because bard environment in diesel engine combustion chamber, solving the problem of durabiUty of TBC is important. DurabiUty of thermal barrier coatings(TBC is liınited by two main failure mechanisms: Therınal expansion nlİsmatch betwcen bond coat and top coat and bond coat oxidation. Both of these can cause failure of the ceramic top coat. Developments of recent years sholv that bond coats \\Vith higher oxidation resistance tend to have better coating system cyclic lives

  17. Thermal contact algorithms in SIERRA mechanics : mathematical background, numerical verification, and evaluation of performance.

    Energy Technology Data Exchange (ETDEWEB)

    Copps, Kevin D.; Carnes, Brian R.

    2008-04-01

    We examine algorithms for the finite element approximation of thermal contact models. We focus on the implementation of thermal contact algorithms in SIERRA Mechanics. Following the mathematical formulation of models for tied contact and resistance contact, we present three numerical algorithms: (1) the multi-point constraint (MPC) algorithm, (2) a resistance algorithm, and (3) a new generalized algorithm. We compare and contrast both the correctness and performance of the algorithms in three test problems. We tabulate the convergence rates of global norms of the temperature solution on sequentially refined meshes. We present the results of a parameter study of the effect of contact search tolerances. We outline best practices in using the software for predictive simulations, and suggest future improvements to the implementation.

  18. Preparation and Characterization of Chitosan/Agar Blended Films: Part 2. Thermal, Mechanical, and Surface Properties

    Directory of Open Access Journals (Sweden)

    Esam A. Elhefian

    2012-01-01

    Full Text Available Chitosan/agar (CS/AG films were prepared by blending different proportions of chitosan and agar (considering chitosan as the major component in solution forms. The thermal stability of the blended films was studied using thermal gravimetric analysis (TGA. It was revealed that chitosan and agar form a compatible blend. Studying the mechanical properties of the films showed a decrease in the tensile strength and elongation at break with increasing agar content. Blending of agar with chitosan at all proportions was found to form hydrogel films with enhanced swelling compared to the pure chitosan one. Static water contact angle measurements confirmed the increasing affinity of the blended films towards water suggesting that blending of agar with chitosan improves the wettability of the obtained films.

  19. A Study on Variations of Mechanical Properties of Carbon-epoxy Composites with Thermal Fatigue Cycles or Thermal Shock Cycles

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D.S.; Park, S.M. [Myongji University, Suwon (Korea)

    2000-05-01

    Applications of composites materials have been in progress noticeably in manufacturing areas of automotive, aircraft and in other industries, resulting in ensuing research activities. Carbon-epoxy, one of major composite materials, is investigated for its thermal characteristics. Upon treatments of the composite material with repeated heatings and coolings variation of its elastic constants are monitored to reveal the thermal nature of the composite material. In this study, generally, changes in elastic constants are observed to occur mostly during the first 10{approx}20 thermal cycles. Values of G{sub 13} remain almost unchanged except a minor decrease. However in the observed small changes thermal shocks produce less effect than thermal fatigues. On the other hand, values of E{sub 1} show gradual increases with the number of applied thermal cycles and temperatures. Meanwhile, values of E{sub 2} and G{sub 23} decrease to a certain extent in the early stage during the applications of thermal cycling but are not appreciably affected by frequencies of thermal cycles. Also, thermal shocks are observed to induce different effects depending on treatment temperatures. (author). 13 refs., 17 figs.

  20. Measuring and interpreting the mechanical thermal noise spectrum in a MEMS

    Science.gov (United States)

    Rocha, L. A.; Cretu, E.; Wolffenbuttel, R. F.

    2005-07-01

    The meta-stability of the pull-in displacement of an electrostatically operated parallel plate micromechanical structure is used for the capacitive measurement of the mechanical-thermal noise spectrum in a MEMS. Pull-in time depends on force and is not affected by the input-referred noise of the readout circuit. Repeatedly bringing the microstructure to pull-in while measuring the pull-in time followed by FFT enables the measurement of the mechanical noise spectrum with a non-mechanical noise level set primarily by the resolution of the time measurement. The white noise level is found to be in agreement with the theory on damping. The 1/f noise spectrum is found to be independent of ambient gas pressure with a 1/f noise-white noise cross-over frequency at 0.007 Hz for a 1 bar gas pressure and is reproducible for devices fabricated in the same process and the same run.

  1. Mechanisms governing the interfacial delamination of thermal barrier coating system with double ceramic layers

    Science.gov (United States)

    Xu, Rong; Fan, Xueling; Wang, T. J.

    2016-05-01

    A systematic study of factors affecting the interfacial delamination of thermal barrier coating system (TBCs) with double ceramic layers (DCL) is presented. Crack driving forces for delaminations at two weak interfaces are examined. The results show that a thicker outermost ceramic layer can induce dramatic increase in crack driving force and make the interface between two ceramic coatings become more prone to delamination. The behavior is shown to be more prominent in TBCs with stiffer outmost coating. The thickness ratio of two ceramic layers is an important parameter for controlling the failure mechanisms and determining the lifetime of DCL TBCs under inservice condition. By accounting for the influences of thickness ratio of two ceramic layers and interfacial fracture toughnesses of two involved interfaces, the fracture mechanism map of DCL TBCs has been constructed, in which different failure mechanisms are identified. The results quanlitatively agree with the aviliable experimental data.

  2. Quantum corrected non-thermal radiation spectrum from the tunnelling mechanism

    CERN Document Server

    Chakraborty, Subenoy; Corda, Christian

    2015-01-01

    Tunnelling mechanism is today considered a popular and widely used method in describing Hawking radiation. However, in relation to black hole (BH) emission, this mechanism is mostly used to obtain the Hawking temperature by comparing the probability of emission of an outgoing particle with the Boltzmann factor. On the other hand, Banerjee and Majhi reformulated the tunnelling framework deriving a black body spectrum through the density matrix for the outgoing modes for both the Bose-Einstein distribution and the Fermi-Dirac distribution. In contrast, Parikh and Wilczek introduced a correction term performing an exact calculation of the action for a tunnelling spherically symmetric particle and, as a result, the probability of emission of an outgoing particle corresponds to a non-strictly thermal radiation spectrum. Recently, one of us (C. Corda) introduced a BH effective state and was able to obtain a non-strictly black body spectrum from the tunnelling mechanism corresponding to the probability of emission o...

  3. Alkali halide solutions under thermal gradients: soret coefficients and heat transfer mechanisms.

    Science.gov (United States)

    Römer, Frank; Wang, Zilin; Wiegand, Simone; Bresme, Fernando

    2013-07-11

    We report an extensive analysis of the non-equilibrium response of alkali halide aqueous solutions (Na(+)/K(+)-Cl(-)) to thermal gradients using state of the art non-equilibrium molecular dynamics simulations and thermal diffusion forced Rayleigh scattering experiments. The coupling between the thermal gradient and the resulting ionic salt mass flux is quantified through the Soret coefficient. We find the Soret coefficient is of the order of 10(-3) K(-1) for a wide range of concentrations. These relatively simple solutions feature a very rich behavior. The Soret coefficient decreases with concentration at high temperatures (higher than T ∼ 315 K), whereas it increases at lower temperatures. In agreement with previous experiments, we find evidence for sign inversion in the Soret coefficient of NaCl and KCl solutions. We use an atomistic non-equilibrium molecular dynamics approach to compute the Soret coefficients in a wide range of conditions and to attain further microscopic insight on the heat transport mechanism and the behavior of the Soret coefficient in aqueous solutions. The models employed in this work reproduce the magnitude of the Soret coefficient, and the general dependence of this coefficient with temperature and salt concentration. We use the computer simulations as a microscopic approach to establish a correlation between the sign and magnitude of the Soret coefficients and ionic solvation and hydrogen bond structure of the solutions. Finally, we report an analysis of heat transport in ionic solution by quantifying the solution thermal conductivity as a function of concentration. The simulations accurately reproduce the decrease of the thermal conductivity with increasing salt concentration that is observed in experiments. An explanation of this behavior is provided.

  4. Surface-effects-dominated thermal and mechanical responses of zinc oxide nanobelts

    Institute of Scientific and Technical Information of China (English)

    A.J.Kulkarni; M.Zhou

    2006-01-01

    Molecular dynamics(MD)simulations are carried out to characterize the mechanical and thermal responses of [ol(l)o]-oriented ZnO nanobelts with lateral dimensions of 21.22(A)×18.95(A),31.02(A)×29.42(A) and 40.81(A)×39.89(A) over the temperature range of 300-1000 K. The Young's modulus and thermal conductivity of the nanobelts are evaluated. Significant surface effects on properties due to the highsurface-to-volume ratios of the nanobelts are observed. For the mechanical response, surface-stress-induced internal stress plays an important role. For the thermal response, surface scattering of phonons dominates. Calculations show that the Young's modulus is higher than the corresponding value for bulk ZnO and decreases by~33%as the lateral dimensions increase from 21.22(A)×18.95(A) to 40.8l(A)×39.89(A).The thermal conductivity is one order of magnitude lower than the corresponding value for bulk ZnO single crystal and decreases with wire size. Specifically, the conductivity of the 21.22(A)×18.95(A) beltis approximately(31-18)% lower than that of the 40.81(A)×39.89(A) belt over the temperature range analyzed. A significant dependence of properties on temperature is also observed. with the Young's modulus decreasing on average by 12% and the conductivity decreasing by 50% as temperature increases from 300 K to 1000 K.

  5. Mechanism of reduction in hydrogen atmosphere and thermal transformation of synthetic ferrihydrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Masina, C.J., E-mail: colani.masina@nmmu.ac.za [Centre for HRTEM, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth (South Africa); Neethling, J.H.; Olivier, E.J. [Centre for HRTEM, Nelson Mandela Metropolitan University, P.O. Box 77000, Port Elizabeth (South Africa); Ferg, E. [Department of Chemistry, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Manzini, S.; Lodya, L.; Mohlala, P.; Ngobeni, M.W. [Sasol Technology R and D, 1 Klasie Havenga Road, Sasolburg (South Africa)

    2015-01-10

    Highlights: • Magnetic measurements used to study thermal transformation of ferrihydrite. • Reduction mechanisms of ferrihydrite were monitored by TPR, MS, and in-situ XRD. • Nanocrystalline Fe was produced by the reducing ferrihydrite in H{sub 2}. • The presence of SiO{sub 2} in ferrihydrite alters the reduction pathway of ferrihydrite. - Abstract: The thermal transformation under vacuum and the reduction behavior in hydrogen atmosphere of 2- and 6-line ferrihydrite (FeOOH·nH{sub 2}O) as well as 2-line FeOOH·nH{sub 2}O deposited onto silica are reported. The investigation methods include magnetization measurements, temperature programmed reduction, in-situ X-ray diffraction and Mössbauer spectroscopy. The thermal transformation of FeOOH·nH{sub 2}O to hematite (α-Fe{sub 2}O{sub 3}) was monitored through changes in the magnetization as a function of temperature; it appears to proceed through the loss of the lattice water and sintering accompanied by improved crystallinity and structural changes. Such a transformation is initiated at T ∼ 580 K for 2-line and 6-line FeOOH·nH{sub 2}O and at T ∼ 660 K for 2-line FeOOH·nH{sub 2}O/SiO{sub 2}, i.e., the presence of SiO{sub 2} appears to inhibit the transformation. SiO{sub 2} also tends to prevent the increase of the crystallite size above a certain threshold value. Reduction reactions are initiated at relatively lower temperatures (∼480 K) implying that a gaseous environment facilitates the thermal dehydration/dehydroxylation process. Three different reduction mechanisms of FeOOH·nH{sub 2}O to metallic iron (α-Fe) are observed: a two-stage process via magnetite (Fe{sub 3}O{sub 4}) as an intermediate phase for 2-line FeOOH·nH{sub 2}O, a three-step reduction involving Fe{sub 3}O{sub 4} and wüstite (FeO) as intermediate phases for 2-line FeOOH·nH{sub 2}O/SiO{sub 2} and a thermal transformation to α-Fe{sub 2}O{sub 3} followed by a two-step reduction via Fe{sub 3}O{sub 4} intermediate for 6-line Fe

  6. Effects of electron irradiation in space environment on thermal and mechanical properties of carbon fiber/bismaleimide composite

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Qi, E-mail: yuqi1027@126.com [Liaoning Key Laboratory of Advanced Polymer Matrix Composites and Faculty of Aerospace Engineering, Shenyang Aerospace University, Shenyang 110136 (China); Chen, Ping, E-mail: chenping_898@126.com [Liaoning Key Laboratory of Advanced Polymer Matrix Composites and Faculty of Aerospace Engineering, Shenyang Aerospace University, Shenyang 110136 (China); State Key Laboratory of Fine Chemicals and School of Chemical Engineering, Dalian University of Technology, Dalian 116024 (China); Gao, Yu; Ma, Keming; Lu, Chun; Xiong, Xuhai [Liaoning Key Laboratory of Advanced Polymer Matrix Composites and Faculty of Aerospace Engineering, Shenyang Aerospace University, Shenyang 110136 (China)

    2014-10-01

    Highlights: •Electron irradiation decreased the storage modulus finally. •T{sub g} decreased first and then increased and finally decreased. •The thermal stability was reduced and then improved and finally decreased. •The changing trend of flexural strength and ILSS are consistent. -- Abstract: The effects of electron irradiation in simulated space environment on thermal and mechanical properties of high performance carbon fiber/bismaleimide composites were investigated. The dynamic mechanical properties of the composites exposed to different fluences of electron irradiation were evaluated by Dynamic mechanical analysis (DMA). Thermogravimetric analysis was applied to investigate the changes in thermal stability of the resin matrix after exposure to electron irradiation. The changes in mechanical properties of the composites were evaluated by flexural strength and interlaminar shear strength (ILSS). The results indicated that electron irradiation in high vacuum had an impact on thermal and mechanical properties of CF/BMI composites, which depends on irradiation fluence. At lower irradiation fluences less than 5 × 10{sup 15} cm{sup −2}, the dynamic storage modulus, cross-linking degree, thermal stability and mechanical properties that were determined by a competing effect between chain scission and cross-linking process, decreased firstly and then increased. While at higher fluences beyond 5 × 10{sup 15} cm{sup −2}, the chain scission process was dominant and thus led to the degradation in thermal and mechanical properties of the composites.

  7. Cutaneous neurturin overexpression alters mechanical, thermal, and cold responsiveness in physiologically identified primary afferents.

    Science.gov (United States)

    Jankowski, Michael P; Baumbauer, Kyle M; Wang, Ting; Albers, Kathryn M; Davis, Brian M; Koerber, H Richard

    2017-03-01

    Neurotrophic factors play an important role in the regulation of functional properties of sensory neurons under normal and pathological conditions. The GDNF family member neurturin is one such factor that has been linked to modulating responsiveness to peripheral stimuli. Neurturin binds to the GFRα2 receptor, a receptor found primarily in isolectin B4-expressing polymodal cutaneous nociceptors. Previous work has shown that knockout of GFRα2 alters heat, but not mechanical, responses in dissociated sensory neurons and reduces pain-related behaviors during the second phase of the formalin test. Research has also shown that overexpression of neurturin in basal keratinocytes increases behavioral responsiveness to mechanical stimulation and innocuous cooling of the skin without affecting noxious heat responses. Here we directly examined the impact of neurturin overexpression on cutaneous afferent function. We compared physiological responses of individual sensory neurons to mechanical and thermal stimulation of the skin, using an ex vivo skin-nerve-dorsal root ganglion-spinal cord preparation produced from neurturin-overexpressing (NRTN/OE) mice and wild-type littermate controls. We found that neurturin overexpression increases responsiveness to innocuous mechanical stimuli in A-fiber nociceptors, alters thermal responses in the polymodal subpopulation of C-fiber sensory neurons, and changes the relative numbers of mechanically sensitive but thermally insensitive C-fiber afferents. These results demonstrate the potential roles of different functional groups of sensory neurons in the behavioral changes observed in mice overexpressing cutaneous neurturin and highlight the importance of neurturin in regulating cutaneous afferent response properties.NEW & NOTEWORTHY GDNF family neurotrophic factors regulate the development and function of primary sensory neurons. Of these, neurturin has been shown to modulate mechanical and cooling sensitivity behaviorally. Here we show

  8. Coaxial carbon@boron nitride nanotube arrays with enhanced thermal stability and compressive mechanical properties

    Science.gov (United States)

    Jing, Lin; Tay, Roland Yingjie; Li, Hongling; Tsang, Siu Hon; Huang, Jingfeng; Tan, Dunlin; Zhang, Bowei; Teo, Edwin Hang Tong; Tok, Alfred Iing Yoong

    2016-05-01

    Vertically aligned carbon nanotube (CNT) arrays have aroused considerable interest because of their remarkable mechanical properties. However, the mechanical behaviour of as-synthesized CNT arrays could vary drastically at a macro-scale depending on their morphologies, dimensions and array density, which are determined by the synthesis method. Here, we demonstrate a coaxial carbon@boron nitride nanotube (C@BNNT) array with enhanced compressive strength and shape recoverability. CNT arrays are grown using a commercially available thermal chemical vapor deposition (TCVD) technique and an outer BNNT with a wall thickness up to 1.37 nm is introduced by a post-growth TCVD treatment. Importantly, compared to the as-grown CNT arrays which deform almost plastically upon compression, the coaxial C@BNNT arrays exhibit an impressive ~4-fold increase in compressive strength with nearly full recovery after the first compression cycle at a 50% strain (76% recovery maintained after 10 cycles), as well as a significantly high and persistent energy dissipation ratio (~60% at a 50% strain after 100 cycles), attributed to the synergistic effect between the CNT and outer BNNT. Additionally, the as-prepared C@BNNT arrays show an improved structural stability in air at elevated temperatures, attributing to the outstanding thermal stability of the outer BNNT. This work provides new insights into tailoring the mechanical and thermal behaviours of arbitrary CNT arrays which enables a broader range of applications.Vertically aligned carbon nanotube (CNT) arrays have aroused considerable interest because of their remarkable mechanical properties. However, the mechanical behaviour of as-synthesized CNT arrays could vary drastically at a macro-scale depending on their morphologies, dimensions and array density, which are determined by the synthesis method. Here, we demonstrate a coaxial carbon@boron nitride nanotube (C@BNNT) array with enhanced compressive strength and shape recoverability

  9. Quantitative exploration of the mechanisms behind the urban thermal environment in Beijing

    Institute of Scientific and Technical Information of China (English)

    Dan Meng; Xiaojuan Li; Wenji Zhao; Huili Gong

    2009-01-01

    The driving mechanism behind the formation of urban thermal environments is the result of a combination of factors.Beijing was chosen as the study area,and the technique of principal component analysis (PCA) was used.A spatial regression method was also applied for quantitative explanation of the thermal mechanism.Multiple Landsat thematic mapper images were used to quantify potential causing factors.Considering the eigenvalues of each factor and its relationship with land surface temperature,the first three principal components (PCs) are regarded as the main causative factors explaining the mechanism as independent variables.The first three PCs mainly reflect urban construction,road density and the normalized difference vegetation index (NDVI),respectively.Ordinary least squares,spatial lag and spatial error regression models were established separately for the relationships between the first three PCs and land surface temperature (LST).In the two spatial regression models,z-statistics for both the spatial lag parameter (ρ) and spatial residual parameter (λ) are significant,indicating the necessity of using spatial regression to replace the OLS regression model,as well as indicating that the spatial error regression model is superior to the spatial lag regression model.Overall,the normalized difference builtup index (NDBI) and road density are the most significant positive contributions to LST.

  10. Change Spectroscopic, thermal and mechanical studies of PU/PVC blends

    Energy Technology Data Exchange (ETDEWEB)

    Hezma, A.M. [Spectroscopy Department, Physics Division, National Research Center, Giza (Egypt); Elashmawi, I.S. [Spectroscopy Department, Physics Division, National Research Center, Giza (Egypt); Physic Department, Faculty of Science, Taibah University, Al-Ula (Saudi Arabia); Rajeh, A., E-mail: a.rajeh88@yahoo.com [Physic Department, Faculty of Science, Amran University, Sa' dah (Yemen); Physics Department, Faculty of science, Mansoura University, Mansoura (Egypt); Kamal, Mustafa [Physics Department, Faculty of science, Mansoura University, Mansoura (Egypt)

    2016-08-15

    Blends of polyurethane (PU) and polyvinyl chloride (PVC) with different concentrations were prepared by casting method. The effects of PU on PVC blends was examined by Fourier transform-infrared (FTIR), Ultra-violet visible studies (UV/VIS.), X-ray diffraction (XRD), Thermogravimetric (TGA), Differential scanning calorimetry (DSC), and mechanical properties (stress–strain curve). The interaction between PU and PVC was examined by FT-IR through the absorbance of the N–H groups and was correlated to mechanical/thermal properties. Ultra-violet visible said that optical energy gap decrease with increasing concentration of PU. Differential scanning calorimetry results was observed a single glass transition temperature (T{sub g}) for blends this confirming existence miscibility within the blends. The causes for best thermal stability of some blends may be described by measurements of interactions between C=O groups of PU and the α-hydrogen of PVC or a dipole–dipole –C=O..Cl–C– interactions. Significant alterations in FTIR, X-ray and DSC examination shows an interactions between blends had good miscibility. X-ray shows some alterations in the intensity with additional PU. PU change the mechanical behavior of PVC through of the blends. When polyurethane content increase causes polyvinyl chloride tensile strength decreases and elongation at break increase.

  11. Thermal and mechanical properties of blends of LDPE and EVA crosslinked by electron beam radiation

    Science.gov (United States)

    Borhani Zarandi, Mahmoud; Amrollahi Bioki, Hojjat

    2013-08-01

    Low density polyethylene (LDPE) blends with different percentages of ethylene vinyl acetate (EVA) irradiated with 10 MeV electron beam in the range of 50-250 kGy at room temperature. The effect of irradiation and EVA content on the mechanical and thermal properties of LDPE was studied. It was revealed that for all blends increasing the applied dose up to 150 kGy would result in decrease in the specific heat capacity (cp) and thermal conductivity (k) of LDPE and then raised slightly with further increased in radiation doses. The gel content showed that under the irradiation, the crosslinking density at each irradiation dose depends almost on the amorphous portions of the LDPE/EVA. The mechanical properties of LDPE/EVA blends were found to be influenced by the electron beam irradiation and EVA content. It can be deduced that the mechanical properties of LDPE are improved by blending with EVA and irradiated by electron beam. Fourier transform infrared (FTIR) spectroscopy was used to characterize the structure of LDPE. Result indicates small variation in crystalline content, which could be increased or decreased on the formation of important bond groups.

  12. Quantum Corrected Non-Thermal Radiation Spectrum from the Tunnelling Mechanism

    Directory of Open Access Journals (Sweden)

    Subenoy Chakraborty

    2015-06-01

    Full Text Available The tunnelling mechanism is today considered a popular and widely used method in describing Hawking radiation. However, in relation to black hole (BH emission, this mechanism is mostly used to obtain the Hawking temperature by comparing the probability of emission of an outgoing particle with the Boltzmann factor. On the other hand, Banerjee and Majhi reformulated the tunnelling framework deriving a black body spectrum through the density matrix for the outgoing modes for both the Bose-Einstein distribution and the Fermi-Dirac distribution. In contrast, Parikh and Wilczek introduced a correction term performing an exact calculation of the action for a tunnelling spherically symmetric particle and, as a result, the probability of emission of an outgoing particle corresponds to a non-strictly thermal radiation spectrum. Recently, one of us (C. Corda introduced a BH effective state and was able to obtain a non-strictly black body spectrum from the tunnelling mechanism corresponding to the probability of emission of an outgoing particle found by Parikh and Wilczek. The present work introduces the quantum corrected effective temperature and the corresponding quantum corrected effective metric is written using Hawking’s periodicity arguments. Thus, we obtain further corrections to the non-strictly thermal BH radiation spectrum as the final distributions take into account both the BH dynamical geometry during the emission of the particle and the quantum corrections to the semiclassical Hawking temperature.

  13. Exhaust gas analysis and formation mechanism of SiC nanowires synthesized by thermal evaporation method

    Directory of Open Access Journals (Sweden)

    Noppasint Jiraborvornpongsa

    2014-09-01

    Full Text Available Silicon carbide nanowires (SiCNWs are a set of promising reinforcement materials due to their superior properties. However, formation mechanism of the SiCNWs synthesized by the thermal evaporation method without metal catalyst is still unclear. To understand the formation mechanism, SiCNWs were synthesized by the thermal evaporation method at 1350 °C using a pre-oxidized Si powder and CH4 gas as precursors. SiCNWs obtained by this method were β-SiC/SiO2 core–shell nanowires with average diameter about 55 nm and with a length up to 1 mm. The exhaust gases during the SiCNWs synthesis process were examined by gas chromatography and the photographs of growth activity of SiCNWs inside the furnace were captured. CO gas was detected during the active formation of SiCNWs. It was clarified that CO gas was one of the byproducts from SiCNWs synthesis process, and the formation reaction of SiCNWs should be 3SiO(g + 3C(s → 2SiC(s + SiO2(s + CO(g. The formation of SiCNWs was discussed based on the oxide-assisted-growth mechanism.

  14. Change Spectroscopic, thermal and mechanical studies of PU/PVC blends

    Science.gov (United States)

    Hezma, A. M.; Elashmawi, I. S.; Rajeh, A.; Kamal, Mustafa

    2016-08-01

    Blends of polyurethane (PU) and polyvinyl chloride (PVC) with different concentrations were prepared by casting method. The effects of PU on PVC blends was examined by Fourier transform-infrared (FTIR), Ultra-violet visible studies (UV/VIS.), X-ray diffraction (XRD), Thermogravimetric (TGA), Differential scanning calorimetry (DSC), and mechanical properties (stress-strain curve). The interaction between PU and PVC was examined by FT-IR through the absorbance of the N-H groups and was correlated to mechanical/thermal properties. Ultra-violet visible said that optical energy gap decrease with increasing concentration of PU. Differential scanning calorimetry results was observed a single glass transition temperature (Tg) for blends this confirming existence miscibility within the blends. The causes for best thermal stability of some blends may be described by measurements of interactions between C=O groups of PU and the α-hydrogen of PVC or a dipole-dipole -C=O..Cl-C- interactions. Significant alterations in FTIR, X-ray and DSC examination shows an interactions between blends had good miscibility. X-ray shows some alterations in the intensity with additional PU. PU change the mechanical behavior of PVC through of the blends. When polyurethane content increase causes polyvinyl chloride tensile strength decreases and elongation at break increase.

  15. Influence of some crosslinking agents on thermal and mechanical properties of electron beam irradiated polylactide

    Energy Technology Data Exchange (ETDEWEB)

    Rytlewski, Piotr, E-mail: prytlewski@ukw.edu.p [Department of Materials Engineering, Kazimierz Wielki University, ul. Chodkiewicza 30, 85-064 Bydgoszcz (Poland); Malinowski, RafaL [Institute for Engineering of Polymer Materials and Dyes, ul. M. SkLodowskiej-Curie 55, 87-100 Torun (Poland); Moraczewski, Krzysztof [Department of Materials Engineering, Kazimierz Wielki University, ul. Chodkiewicza 30, 85-064 Bydgoszcz (Poland); Zenkiewicz, Marian [Institute for Engineering of Polymer Materials and Dyes, ul. M. SkLodowskiej-Curie 55, 87-100 Torun (Poland)

    2010-10-15

    The aim of this article was to determine and compare the influence of trimethylopropane trimethacylate (TMPTA) and trially isocyanurate (TAIC) crosslinking agents on thermal and mechanical properties of electron beam irradiated polylactide (PLA). The blends were made of PLA mixed with 3 wt% of TMPTA (PLA/TMPTA), and PLA mixed with 3 wt% of TAIC (PLA/TAIC). Injection moulded samples were irradiated with the use of high energy (10 MeV) electron beam at various radiation doses to crosslinking PLA macromolecules. Thermal and mechanical properties were investigated by means of differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile strength, and impact strength measurements. The samples were also characterized by Fourier transform infrared spectroscopy (FTIR). It was found that under the influence of electron irradiation PLA/TMPTA samples underwent degradation while PLA/TAIC samples became crosslinked. Tensile and impact strengths of PLA/TMPTA samples decreased with increasing radiation dose while an enhancement of these properties for PLA/TAIC samples was observed.

  16. Mechanical and Thermal Stability Properties of Modified Rice Straw Fiber Blend with Polycaprolactone Composite

    Directory of Open Access Journals (Sweden)

    Roshanak Khandanlou

    2014-01-01

    Full Text Available The goal of this study was to investigate the effect of modified rice straw (ORS on the mechanical and thermal properties of modified rice straw/polycaprolactone composites (ORS/PCL-Cs. The composites (Cs of polycaprolactone (PCL with ORS were successfully synthesized using the solution-casting method. The RS modified with octadecylamine (ODA as an organic modifier. The prepared composites were characterized by using powder X-ray diffraction (XRD, thermogravimetric analysis (TGA, scanning electron microscopy (SEM, and Fourier transforms infrared spectroscopy (FT-IR, and mechanical properties were investigated. Composites of ORS/PCL showed superior mechanical properties due to greater compatibility of ORS with PCL. The XRD results showed that the intensity of the peaks decreased with the increase of ORS content from 1.0 to 7.0 wt.% in comparison with PCL peaks. Tensile measurement showed an increase in tensile modulus but a decrease in tensile strength and elongation at break as the ORS contents are increased from 1.0 to 7.0 wt.%; on the other hand, tensile strength was improved with the addition of 5.0 wt.% of ORS. Thermal stability was decreased with the increase of ORS contents. SEM micrograph indicated good dispersion of ORS into the matrix, and FT-IR spectroscopy showed that the interaction between PCL and ORS is physical interaction.

  17. High Density Polyethylene Composites Reinforced with Hybrid Inorganic Fillers: Morphology, Mechanical and Thermal Expansion Performance

    Directory of Open Access Journals (Sweden)

    Birm-June Kim

    2013-09-01

    Full Text Available The effect of individual and combined talc and glass fibers (GFs on mechanical and thermal expansion performance of the filled high density polyethylene (HDPE composites was studied. Several published models were adapted to fit the measured tensile modulus and strength of various composite systems. It was shown that the use of silane-modified GFs had a much larger effect in improving mechanical properties and in reducing linear coefficient of thermal expansion (LCTE values of filled composites, compared with the use of un-modified talc particles due to enhanced bonding to the matrix, larger aspect ratio, and fiber alignment for GFs. Mechanical properties and LCTE values of composites with combined talc and GF fillers varied with talc and GF ratio at a given total filler loading level. The use of a larger portion of GFs in the mix can lead to better composite performance, while the use of talc can help lower the composite costs and increase its recyclability. The use of 30 wt % combined filler seems necessary to control LCTE values of filled HDPE in the data value range generally reported for commercial wood plastic composites. Tensile modulus for talc-filled composite can be predicted with rule of mixture, while a PPA-based model can be used to predict the modulus and strength of GF-filled composites.

  18. Electrical, Mechanical, and Thermal Properties of LDPE Graphene Nanoplatelets Composites Produced by Means of Melt Extrusion Process

    Directory of Open Access Journals (Sweden)

    Karolina Gaska

    2017-01-01

    Full Text Available Composites of LDPE filled with different amounts of graphene nanoplatelets (GnP were prepared in form of films by means of precoating technique and single screw melt-extrusion using two types of screws, compression and mixing. This manufacturing process imposes strong anisotropy on the sample’s morphology, in which the nanoplatelets become oriented along the extrusion direction. Such orientation of GnP in LDPE matrix is confirmed by scanning electron microscopy observations and it yields unique electrical properties. As compared to pure LDPE, significant reductions of the through-plane conductivity are found for the composites at relatively low electric fields (<20 kV/mm at low filler concentrations. Above the field level of 20 kV/mm, a crossover effect is observed that results in a strong field dependency of the conductivity where the non-linear behavior starts to dominate. Moreover, differential scanning calorimetry (DSC results indicate a decrease in polymer crystallinity of the composite matrix with increasing filler content, whereas thermogravimetric (TG analysis shows a slight increase in the material’s thermal stability. Application of GnP also leads to improvement of mechanical properties, manifested by the increase of Young’s modulus and tensile strength in both types of samples.

  19. Influence of boehmite nanoparticle loading on the mechanical, thermal, and rheological properties of biodegradable polylactide/ poly(e-caprolactone) blends

    CSIR Research Space (South Africa)

    Agwuncha, SC

    2015-01-01

    Full Text Available -1 Macromolecular Materials and Engineering Vol. 300(1), 31-47 Influence of Boehmite Nanoparticle Loading on the Mechanical, Thermal, and Rheological Properties of Biodegradable Polylactide/Poly(e-caprolactone) Blendsa Stephen C. Agwuncha, Suprakas Sinha...

  20. Kinetics and mechanism of the thermal decomposition of unsaturated aldehydes: benzaldehyde, 2-butenal, and 2-furaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Grela, M.A.; Colussi, A.J.

    1986-01-30

    The thermal unimolecular decomposition of benzaldehyde (BA), crotonaldehyde (CA), and furfural (FA) have been investigated in a flow reactor at very low pressures by modulated beam mass spectrometry above 1040 K. Each reaction proceeds by a different mechanism. Whereas BA decomposes by C(O)-H bond fission CA readily undergoes decarbonylation to propene via a three-center transition-state reaction. FA decomposition into vinylketene and CO involves ring opening followed by H-atom transfer in the resulting biradical. Overall high-pressure Arrhenius parameters for the three reactions are derived from kinetic data. 26 references, 4 figures, 1 table.

  1. Thermal and mechanical properties of a DNA model with solvation barrier

    CERN Document Server

    Tapia-Rojo, Rafael; Falo, Fernando

    2010-01-01

    We study the thermal and mechanical behavior of DNA denaturation in the frame of the mesoscopic Peyrard- Bishop-Dauxois model with the inclusion of solvent interaction. By analyzing the melting transition of a homogeneous A-T sequence, we are able to set suitable values of the parameters of the model and study the formation and stability of bubbles in the system. Then, we focus on the case of the P5 promoter sequence and use the Principal Component Analysis of the trajectories to extract the main information on the dynamical behavior of the system. We find that this analysis method gives an excellent agreement with previous biological results.

  2. The dependence of optical turbulence on thermal and mechanical forces over the sea

    Science.gov (United States)

    van Eijk, Alexander M. J.; Sprung, Detlev; Sucher, Erik; Eisele, Christian; Seiffer, Dirk; Stein, Karin

    2016-09-01

    Optical turbulence for over-water conditions was investigated in a long-term experiment over False Bay near Cape Town, South Africa. A sonic anemometer and two boundary-layer scintillometers were deployed to access in-situ turbulence as well as the integrated turbulence over two 1.8 and 8.7 km paths. Statistical analysis reveals spatial temporal variations of the turbulence conditions over False Bay, which might be related to differences in the atmospheric conditions and/or the surface (water) temperatures. An analysis in terms of mechanical and thermal forcing reveals that the latter factor is more dominant in determining the turbulence strength.

  3. Passive ultrasonics using sub-Nyquist sampling of high-frequency thermal-mechanical noise.

    Science.gov (United States)

    Sabra, Karim G; Romberg, Justin; Lani, Shane; Degertekin, F Levent

    2014-06-01

    Monolithic integration of capacitive micromachined ultrasonic transducer arrays with low noise complementary metal oxide semiconductor electronics minimizes interconnect parasitics thus allowing the measurement of thermal-mechanical (TM) noise. This enables passive ultrasonics based on cross-correlations of diffuse TM noise to extract coherent ultrasonic waves propagating between receivers. However, synchronous recording of high-frequency TM noise puts stringent requirements on the analog to digital converter's sampling rate. To alleviate this restriction, high-frequency TM noise cross-correlations (12-25 MHz) were estimated instead using compressed measurements of TM noise which could be digitized at a sampling frequency lower than the Nyquist frequency.

  4. Disturbance due to mechanical and thermal sources in a generalized thermo-microstretch elastic half space

    Indian Academy of Sciences (India)

    Rajneesh Kumar; Sunita Deswal

    2001-12-01

    Disturbances caused by impulsive concentrated mechanical and thermal sources in a homogeneous, isotropic generalized thermo-microstretch elastic medium are studied by the use of Laplace-Hankel transform techniques. The integral transforms are inverted using a numerical technique. Analytical expressions for displacement components, stress, couple stress, microstress and temperature field are derived for different models of generalized thermoelasticity and illustrated graphically. These results for stresses and displacements can be used in estimating the effects of a surface pressure wave. Stretch and micropolar effects on various expressions obtained analytically are also depicted graphically.

  5. Thermal and mechanical response of steel sheets welded by laser process: Preanalysis made by ABAQUS code

    Energy Technology Data Exchange (ETDEWEB)

    Carmignani, B.; Daneri, A.; Giambuzzi, S.; Toselli, G. [ENEA, Bologna (Italy). Centro Ricerche Energia `E. Clementel` - Area Energetica

    1994-11-01

    In this work, the conclusive report on the activity, developed in the frame of the european project EUREKA-FASP (EU353), concerning the numerical simulation of the thermal and mechanical response of steel sheets, welded by a laser welding process, is presented. This type of welding process is of interest in the shipyard field. ABAQUS code, in its implicit version, has been used. Besides the description of the studies concerning more directly the laser welding, simulations of traditional welding processes, executed in order to single out particular aspects and calculation strategies to be utilized for the simulation of the process object of the study made, are presented and discussed.

  6. Determination of thermal and mechanical properties of HDPE-based polymer blends for use in traffic signs

    OpenAIRE

    2016-01-01

    Two recycled high-density polyethylene specimens and two recycled high-density polyethylene blends were characterized in terms of their thermal and mechanical properties with the purpose of assessing their suitability for the construction of traffic signs. Traffic signs constructed from recycled plastics provide an application for materials that otherwise with end up in landfills. The HDPE composite containing 25% LDPE and 5% ABS had the best mechanical and thermal performance. Of importance ...

  7. Effect of food/oral-simulating liquids on dynamic mechanical thermal properties of dental nanohybrid light-cured resin composites.

    Science.gov (United States)

    Vouvoudi, Evangelia C; Sideridou, Irini D

    2013-08-01

    The purpose of this work was the study of the effect of food/oral simulating liquids on the dynamic mechanical thermal properties (viscoelastic properties) of current commercial dental light-cured resin composites characterized as nanohybrids. These nanohybrids were Grandio, Protofill-nano and Tetric EvoCeram. The properties were determined under dry conditions (1h at 37°C after light-curing) and also after storage in dry air, distilled water, artificial saliva SAGF(®) or ethanol/water solution (75 vol%) at 37°C for up 1, 7, 30 or 90 days. Dynamic mechanical thermal analysis tests were performed on a Diamond Dynamic Mechanical Analyzer in bending mode. A frequency of 1Hz and a temperature range of 25-185°C were applied, while the heating rate of 2°C/min was selected to cover mouth temperature and the materials' likely Tg. Storage modulus, loss modulus and tangent delta were plotted against temperature over this period. The Tg of composites was obtained as the temperature indicated by tanδ peak. Moreover, the maximum height of tanδ peak, the width at the half of tanδ maximum and a parameter known as "ζ" parameter were determined. All composites analyzed 1h after light-curing and 1 day in air or in food/oral simulating liquids showed two Tg. All composites stored for 7, 30 or 90 days in any medium showed unique Tg value. Also among the various properties studied the most sensible in the structural changes of composites seems to be the Tg. Storage of composites in dry air at 37°C which is very close to their Tg (40°C) for 1 or 7 days caused post curing reactions, while storage for 30 or 90 days has no further effect on composites. Storage in water or artificial saliva 37°C for 1 or 7 days caused post curing reactions, while storage for 30 or 90 days seems to cause plasticization effect affecting some parameters analogously. Storage in ethanol/water solution (75vol%) 37°C for 1 or 7 days caused also post curing reactions, while storage for 30 or 90 days

  8. The Effect of Thermal Cycling Treatments on the Thermal Stability and Mechanical Properties of a Ti-Based Bulk Metallic Glass Composite

    Directory of Open Access Journals (Sweden)

    Fan Bu

    2016-11-01

    Full Text Available The effect of thermal cycling treatments on the thermal stability and mechanical properties of a Ti48Zr20Nb12Cu5Be15 bulk metallic glass composite (BMGC has been investigated. Results show that moderate thermal cycles in a temperature range of −196 °C (cryogenic temperature, CT to 25 °C (room temperature, RT or annealing time at CT has not induced obvious changes of thermal stability and then it decreases slightly over critical thermal parameters. In addition, the dendritic second phases with a bcc structure are homogeneously embedded in the amorphous matrix; no visible changes are detected, which shows structural stability. Excellent mechanical properties as high as 1599 MPa yield strength and 34% plastic strain are obtained, and the yield strength and elastic modulus also increase gradually. The effect on the stability is analyzed quantitatively by crystallization kinetics and plastic-flow models, and indicates that the reduction of structural relaxation enthalpy, which is related to the degradation of spatial heterogeneity, reduces thermal stability but does not imperatively deteriorate the plasticity.

  9. Carbon nanofiber reinforced epoxy matrix composites and syntactic foams - mechanical, thermal, and electrical properties

    Science.gov (United States)

    Poveda, Ronald Leonel

    The tailorability of composite materials is crucial for use in a wide array of real-world applications, which range from heat-sensitive computer components to fuselage reinforcement on commercial aircraft. The mechanical, electrical, and thermal properties of composites are highly dependent on their material composition, method of fabrication, inclusion orientation, and constituent percentages. The focus of this work is to explore carbon nanofibers (CNFs) as potential nanoscale reinforcement for hollow particle filled polymer composites referred to as syntactic foams. In the present study, polymer composites with high weight fractions of CNFs, ranging from 1-10 wt.%, are used for quasi-static and high strain rate compression analysis, as well as for evaluation and characterization of thermal and electrical properties. It is shown that during compressive characterization of vapor grown carbon nanofiber (CNF)/epoxy composites in the strain rate range of 10-4-2800 s-1, a difference in the fiber failure mechanism is identified based on the strain rate. Results from compression analyses show that the addition of fractions of CNFs and glass microballoons varies the compressive strength and elastic modulus of epoxy composites by as much as 53.6% and 39.9%. The compressive strength and modulus of the syntactic foams is also shown to generally increase by a factor of 3.41 and 2.96, respectively, with increasing strain rate when quasi-static and high strain rate testing data are compared, proving strain rate sensitivity of these reinforced composites. Exposure to moisture over a 6 month period of time is found to reduce the quasi-static and high strain rate strength and modulus, with a maximum of 7% weight gain with select grades of CNF/syntactic foam. The degradation of glass microballoons due to dealkalization is found to be the primary mechanism for reduced mechanical properties, as well as moisture diffusion and weight gain. In terms of thermal analysis results, the

  10. Synthesis and Thermal Decomposition Mechanism of Rare Earth (RE=La, Y, Gd) Salicylates

    Institute of Scientific and Technical Information of China (English)

    LI, Liang-Chao(李良超); ZHOU, Xiang-Chun(周享春); ZHENG, Ren-Wei(郑人卫)

    2004-01-01

    The rare earth (RE=La, Y, Gd) salicylates were synthesized by the rheological phase reaction method. The complexes were characterized by elemental analysis, infrared spectra (IR), X-ray powder diffraction (XRD) and thermal gravity analysis (TG). They can be represented by general formula RE(HSal)3 (RE=La, Y, Gd; HSal=C6H4(OH)COO). The crystals of them are monoclinic and have layered structure. The mechanism of thermal decomposition of rare earth salicylates was studied by using TG, DTA, IR and gas chromatography-mass spectrometry (GC-MS). The thermal decomposition of the rare earth salicylates in nitrogen gas proceeded in three stages: firstly, they were decomposed to form RE2(Sal)3 (Sal=C6H4OCOO) and salicylic acid; then, RE2(Sal)3 were decomposed further to form RE2O(CO3)2 and some organic compounds; finally, RE2O(CO3)2 were decomposed to form rare earth metal oxides (RE2O3) and carbon dioxide. The organic compounds obtained from the second step of the reaction are mainly dibenzofuran, xanthenone, 6H-benzo[c]chromen-6-one, 6-phenyl-6H-benzo[c]chromene, and 1,3-diphenyl-1, 3-dihydro-2-benzofuran.

  11. Thermal protection mechanism of heat pipe in leading edge under hypersonic conditions

    Institute of Scientific and Technical Information of China (English)

    Peng Wengen; He Yurong; Wang Xinzhi; Zhu Jiaqi; Han Jiecai

    2015-01-01

    Sharp local structure, like the leading edge of hypersonic aircraft, confronts a severe aerodynamic heating environment at a Mach number greater than 5. To eliminate the danger of a material failure, a semi-active thermal protection system is proposed by integrating a metallic heat pipe into the structure of the leading edge. An analytical heat-balance model is established from tra-ditional aerodynamic theories, and then thermal and mechanical characteristics of the structure are studied at Mach number 6–8 for three refractory alloys, Inconel 625, C-103, and T-111. The feasi-bility of this simple analytical method as an initial design tool for hypersonic aircraft is assessed through numerical simulations using a finite element method. The results indicate that both the iso-thermal and the maximum temperatures fall but the von Mises stress increases with a longer design length of the leading edge. These two temperatures and the stress rise remarkably at a higher Mach number. Under all investigated hypersonic conditions, with a 3 mm leading edge radius and a 0.15 m design length, the maximum stress exceeds the yield strength of Inconel 625 at Mach num-bers greater than 6, which means a material failure. Moreover, both C-103 and T-111 meet all requirements at Mach number 6–8.

  12. Thermal degradation mechanism of addition-cure liquid silicone rubber with urea-containing silane

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Weizhen; Zeng, Xingrong, E-mail: psxrzeng@gmail.com; Lai, Xuejun; Li, Hongqiang; Chen, Wanjuan; Zhang, Yajun

    2015-04-10

    Highlights: • The urea-containing silane was incorporated into addition-cure liquid silicone rubber (ALSR) via hydrosilylation reaction. • The thermal stability of the ALSR was improved by DEUPAS both in nitrogen and air • The TG–FTIR of evolved gases during degradation was performed. • The possible degradation mechanism of the ALSR samples was proposed. - Abstract: The reactive urea-containing silane, (γ-diethylureidopropyl) allyloxyethoxysilane (DEUPAS), was synthesized by the trans-etherification reaction. The chemical structure was characterized by Fourier transform infrared spectrometry (FTIR) and {sup 1}H nuclear magnetic resonance spectrometry ({sup 1}H NMR). Subsequently, DEUPAS was incorporated into addition-cure liquid silicone rubber (ALSR) via hydrosilylation reaction. The thermal stability of the ALSR samples was investigated by thermogravimetry (TG) and thermogravimetry–Fourier transform infrared spectrometry (TG–FTIR). When DEUPAS was incorporated, the temperature of 10% weight loss and 20% weight loss under air atmosphere were respectively increased by 31 °C and 60 °C compared with those of the ALSR without DEUPAS. Meanwhile, the residual weight at 800 °C increased from 33.5% to 58.7%. It was found that the striking enhancement in thermal stability of the ALSR samples was likely attributed to the decomposition of the urea groups to isocyanic acid, which reacted with hydroxyl groups to inhibit the unzipping depolymerization.

  13. Characterization of thermal cut-off mechanisms in prismatic lithium-ion batteries

    Science.gov (United States)

    Venugopal, Ganesh

    Lithium-ion (Li-ion) cells that are subjected to electrical abuse, overcharge and external short-circuit in particular, exhibit a rapid increase in cell temperature that could potentially lead to catastrophic disassembly of the cell. For this reason these cells are integrated or combined with one or more safety components that are designed to restrict or even prevent current flow through the cell under abusive conditions. In this work, the characteristics of these components in several prismatic Li-ion cells are studied by monitoring the impedance ( Z) at 1 kHz and the open circuit voltage (OCV) of the discharged cells as a function of temperature. All the cells studied were found to use polyethylene-based shutdown (SD) separators that were irreversibly activated within a narrow temperature range between 130 and 135°C. In some cells irreversible cut-off was also provided by a current interrupt device (CID) or a thermal fuse. Both these devices had a circuit-breaker effect, causing the impedance of the cell to rise infinitely and the OCV to drop to zero. In addition to these irreversible cut-off mechanisms, some cells also contained internal or external positive-temperature-coefficient (PTC) devices that could provide current-limiting capability over a very wide temperature range. The interdependence of the thermal behavior of these components on each other and on other thermally dependant processes like cell venting, separator meltdown and weld joint failure are also discussed.

  14. Mechanical, thermal and laser damage threshold analyses of II group metal complexes of thiourea

    Energy Technology Data Exchange (ETDEWEB)

    Dhanuskodi, S., E-mail: dhanus2k3@yahoo.com [School of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu (India); Sabari Girisun, T.C. [School of Physics, Bharathidasan University, Tiruchirappalli 620 024, Tamil Nadu (India); Department of Physics, Bishop Heber College, Tiruchirappalli 620 017, Tamil Nadu (India); Bhagavannarayana, G. [Material Characterization Division, National Physical laboratory, New Delhi 110 012 (India); Uma, S.; Phillip, J. [Sophisticated Test and Instrumentation Center, Cochin University of Science and Technology, Cochin 682 022 (India)

    2011-04-15

    Research highlights: {yields} The role of the Group II metal ions in improving the stability is discussed. {yields} BTCC has a higher heat capacity than BTZC. {yields} Elastic stiffness is found to be higher for BTCC than BTZC. {yields} Microscopy studies confirm the damage is due to thermo-chemical ablation. {yields} BTCC has a higher laser damage threshold than BTZC. - Abstract: Single crystals of thiourea metal complexes with selected Group II metal ions, Zinc and Cadmium, have been grown by solvent evaporation technique. The crystals grown are bisthiourea zinc chloride (BTZC) and bisthiourea cadmium chloride (BTCC). Following an improved photopyroelectric technique, the thermal transport properties have been determined. It is found that BTCC has a higher heat capacity (304.09 J kg{sup -1} K{sup -1}) than BTZC (255.24 J kg{sup -1} K{sup -1}), and hence BTCC has better thermal stability. Vicker's microhardness measurements reveal that these materials have reverse indentation size effect and belong to the category of soft materials. Elastic stiffness is found to be higher for BTCC (1.57 GPa) than BTZC (0.76 GPa). The roles of the Group II metal ions in improving the mechanical and thermal stability of the metal complexes are discussed. Multi-shot laser damage studies on these materials reveal that BTCC has a higher laser damage threshold (15 GW cm{sup -2}) than BTZC (6 GW cm{sup -2}).

  15. RESEARCH ON DISTURBED MECHANISM OF THERMAL NOISES OF THE SURFACE IN ABRUPT GEOTHERMAL ANOMALY

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Geothermal anomaly as a physical phenomenon of an active and latent volcanic area would be well recognized, and abrupt geothermal anomaly should also be understood. However, in practical work, thermal infrared remote sensing techniques are frequently used to monitor geothermal flows of the earth. But then, except for this type of thermal source in the surface thermal field, there still exist a lot of noises in the area where the abrupt geothermal anomaly is generated. By Analyzing the reason, we find that it is brought about by the non-boundless projectioncharacteristics of objects.These noises may be divided into two classes: system noises and random noises. If disturbednoises have comparative stable time sequence law and space sequence law, the noises are called system noises. And because system noises have a certain law, it is easy toremove the noises. On the contrary, if disturbed noises have not law oftime sequence and space sequence, the noises are called random noises. The random noises have the character of non-linearity, uncertainty and indeterminism. For this case, this paper discusses the disturbed mechanism of these noises as well as how to remove them.

  16. Mechanical and thermal properties of NpO2 using LSDA+U approach

    Directory of Open Access Journals (Sweden)

    Lei Jin

    2014-08-01

    Full Text Available The elastic constants, bulk modulus, shear modulus, Young׳s modulus, Debye temperature, isobaric heat capacity and minimum thermal conductivity are estimated for NpO2 using plane-wave pseudopotential method within the local spin density approximation plus Hubbard U (LSDA+U theory. The computed lattice constants are in good agreement with the available experimental results and then three independent elastic constants were computed by means of the stress–strain method. From the knowledge of the elastic constants, the values of Young׳s modulus, Poisson, Debye temperature and minimum thermal conductivity are obtained and they are 218 GPa, 0.288, 453.5 K and 0.99 Wm−1 K−1, respectively. The obtained mechanical and thermal properties of NpO2 are in agreement with the previous experimental and theoretical data. Our investigations which are unobtainable from previous report can provide valuable reference in the future.

  17. Effect of Calcium Sulphate Nanoparticles on Fusion, Mechanical and Thermal Behaviour Polyvinyl Chloride (pvc)

    Science.gov (United States)

    Patil, C. B.; Shisode, P. S.; Kapadi, U. R.; Hundiwale, D. G.; Mahulikar, P. P.

    Calcium Sulphate [CaSO4] was synthesized by in-situ deposition technique and its nano size (60 to 100 nm) was confirmed by Transmission Electron Microscopy (TEM). Composites of the filler CaSO4 (micro and nano) and the matrix poly (vinyl chloride) (PVC) were prepared with different filler loading (0-5 wt. %) by melt mixing. The Brabender torque rheometer equipped with an internal mixer was used for preparation and evaluation of fusion behaviour of composites of different formulations. The effect of nano and micro-CaSO4 content on the structure and properties of composites was studied. The nanostructures and dispersion were studied by wide angle X-ray diffraction (WAXD) and scanning electron microscopy (SEM). The mechanical and thermal properties of PVC/ micro and nano-CaSO4 composites were characterized using Universal Testing Machine (UTM) and Thermo Gravimetric Analyzer (TGA). From the results of WAXD and SEM the flocculation of CaSO4 nanoparticles were observed on the surfaces of PVC matrix. The thermal analysis results showed that the first thermal degradation onset (T onset) of PVC/nano-CaSO4 composites for 1 wt. % of filler were higher as compared with corresponding microcomposites and pristine PVC. However, the tensile strength was decreasing with increasing filler content while, it shows increment in magnitude at 1 and 2 wt. % of nano-CaSO4 as compared with corresponding micro-CaSO4 as well as pristine PVC.

  18. Thermal and mechanical stability of retained austenite in aluminum-containing multiphase TRIP steels

    CERN Document Server

    Zwaag, S; Kruijver, S O; Sietsma, J

    2002-01-01

    Stability of retained austenite is the key issue to understand transformation-induced plasticity (TRIP) effect. In this work, both thermal stability and mechanical stability are investigated by thermo-magnetic as well as in situ conventional X-ray diffraction and micro synchrotron radiation diffraction measurements. The thermal stability in a 0.20C-1.52Mn-0.25Si-0.96Al (wt%) TRIP steel is studied in the temperature range between 5 and 300 K under a constant magnetic field of 5T. It is found that almost all austenite transforms thermally to martensite upon cooling to 5K and M sub s and M sub f temperatures are analyzed to be 355 and 115 K. Transformation kinetics on the fraction versus temperature relation are well described by a model based on thermodynamics. From the in situ conventional X-ray and synchrotron diffraction measurements in a 0.17C-1.46Mn-0.26Si-1.81Al (wt%) steel, the volume fraction of retained austenite is found to decrease as the strain increases according to Ludwigson and Berger relation. T...

  19. Cooling Systems Design in Hot Stamping Tools by a Thermal-Fluid-Mechanical Coupled Approach

    Directory of Open Access Journals (Sweden)

    Tao Lin

    2014-06-01

    Full Text Available Hot stamping tools with cooling systems are the key facilities for hot stamping process of Ultrahigh strength steels (UHSS in automotive industry. Hot stamping tools have significant influence on the final microstructure and properties of the hot stamped parts. In serials production, the tools should be rapidly cooled by cooling water. Hence, design of hot stamping tools with cooling systems is important not only for workpieces of good quality but also for the tools with good cooling performance and long life. In this paper, a new multifield simulation method was proposed for the design of hot stamping tools with cooling system. The deformation of the tools was also analyzed by this method. Based on MpCCI (Mesh-based parallel Code Coupling Interface, thermal-fluid simulation and thermal-fluid-mechanical coupled simulation were performed. Subsequently, the geometrical parameters of the cooling system are investigated for the design. The results show that, both the distance between the ducts and the distance between the ducts and the tools loaded contour have significant influence on the quenching effect. And better quenching effect can be achieved with the shorter distance from the tool surface and with smaller distance between ducts. It is also shown that, thermal expansion is the main reason for deformation of the hot forming tools, which causes the distortion of the cooling ducts, and the stress concentration at corner of the ducts.

  20. Bat-Derived Influenza Hemagglutinin H17 Does Not Bind Canonical Avian or Human Receptors and Most Likely Uses a Unique Entry Mechanism

    Directory of Open Access Journals (Sweden)

    Xiaoman Sun

    2013-03-01

    Full Text Available A new influenza-like virus genome (H17N10 was recently discovered in bats and offers a new perspective about the origin and evolution of influenza viruses. The viral envelope glycoprotein hemagglutinin (HA is responsible for influenza virus receptor binding, fusion, and entry into the cell; therefore, the structure and function of HA H17 was characterized. The 2.70 Å resolution crystal structure revealed that H17 has a typical influenza A virus HA fold, but with some special features, including a distorted putative sialic acid (SA binding site and low thermostability. No binding to either the canonical human α2,6 SA-linkage or avian α2,3 SA-linkage receptor was observed. Furthermore, H17 glycan binding was not detected using a chip covering more than 600 glycans. Our results demonstrate that H17 is unique among characterized HAs and that the bat-derived influenza virus may use a different entry mechanism compared to canonical influenza viruses.

  1. Structures of the Bacillus subtilis glutamine synthetase dodecamer reveal large intersubunit catalytic conformational changes linked to a unique feedback inhibition mechanism.

    Science.gov (United States)

    Murray, David S; Chinnam, Nagababu; Tonthat, Nam Ky; Whitfill, Travis; Wray, Lewis V; Fisher, Susan H; Schumacher, Maria A

    2013-12-13

    Glutamine synthetase (GS), which catalyzes the production of glutamine, plays essential roles in nitrogen metabolism. There are two main bacterial GS isoenzymes, GSI-α and GSI-β. GSI-α enzymes, which have not been structurally characterized, are uniquely feedback-inhibited by Gln. To gain insight into GSI-α function, we performed biochemical and cellular studies and obtained structures for all GSI-α catalytic and regulatory states. GSI-α forms a massive 600-kDa dodecameric machine. Unlike other characterized GS, the Bacillus subtilis enzyme undergoes dramatic intersubunit conformational alterations during formation of the transition state. Remarkably, these changes are required for active site construction. Feedback inhibition arises from a hydrogen bond network between Gln, the catalytic glutamate, and the GSI-α-specific residue, Arg(62), from an adjacent subunit. Notably, Arg(62) must be ejected for proper active site reorganization. Consistent with these findings, an R62A mutation abrogates Gln feedback inhibition but does not affect catalysis. Thus, these data reveal a heretofore unseen restructuring of an enzyme active site that is coupled with an isoenzyme-specific regulatory mechanism. This GSI-α-specific regulatory network could be exploited for inhibitor design against Gram-positive pathogens.

  2. Preparation, Mechanical and Thermal Properties of Cement Board with Expanded Perlite Based Composite Phase Change Material for Improving Buildings Thermal Behavior

    Directory of Open Access Journals (Sweden)

    Rongda Ye

    2015-11-01

    Full Text Available Here we demonstrate the mechanical properties, thermal conductivity, and thermal energy storage performance of construction elements made of cement and form-stable PCM-Rubitherm® RT 28 HC (RT28/expanded perlite (EP composite phase change materials (PCMs. The composite PCMs were prepared by adsorbing RT28 into the pores of EP, in which the mass fraction of RT28 should be limited to be no more than 40 wt %. The adsorbed RT28 is observed to be uniformly confined into the pores of EP. The phase change temperatures of the RT28/EP composite PCMs are very close to that of the pure RT28. The apparent density and compression strength of the composite cubes increase linearly with the mass fraction of RT28. Compared with the thermal conductivity of the boards composed of cement and EP, the thermal conductivities of the composite boards containing RT28 increase by 15%–35% with the mass fraction increasing of RT28. The cubic test rooms that consist of six boards were built to evaluate the thermal energy storage performance, it is found that the maximum temperature different between the outside surface of the top board with the indoor temperature using the composite boards is 13.3 °C higher than that of the boards containing no RT28. The thermal mass increase of the built environment due to the application of composite boards can contribute to improving the indoor thermal comfort and reducing the energy consumption in the buildings.

  3. Experimental Investigation of Mechanical and Thermal properties of sisal fibre reinforced composite and effect of sic filler material

    Science.gov (United States)

    Surya Teja, Malla; Ramana, M. V.; Sriramulu, D.; Rao, C. J.

    2016-09-01

    With a view of exploring the potential use of natural recourses, we made an attempt to fabricate sisal fibre polymer composites by hand lay-up method. Natural fiber composites are renewable, cheap and biodegradable. Their easy availability, lower density, higher specific properties, lower cost, satisfactory mechanical and thermal properties, non-corrosive nature, makes them an attractive ecological alternative to glass, carbon or other man-made synthetic fibers. In this work, the effect of SiC on mechanical and thermal properties of natural sisal fiber composites are investigated. The composite has been made with and without SiC incorporating natural sisal fiber with polyester as bonding material. The experimental outcomes exhibited that the tensile strength of composite with 10%SiC 2.53 times greater than that of composite without SiC. The impact strength of composite with 10% SiC is 1.73 times greater than that of composite without SiC plain polyester. Thermal properties studied include thermal conductivity, specific heat capacity, thermal diffusivity, thermal degradation and stability. Three different samples with 0%, 5%, 10% SiC powder are considered. With the addition of SiC filler powder, thermal conductivity increases, specific heat capacity gradually increases then decreases, thermal diffusivity increases and thermal stability improves with Sic powder.

  4. On the early and developed stages of surface condensation: competition mechanism between interfacial and condensate bulk thermal resistances

    Science.gov (United States)

    Sun, Jie; Wang, Hua Sheng

    2016-10-01

    We use molecular dynamics simulation to investigate the early and developed stages of surface condensation. We find that the liquid-vapor and solid-liquid interfacial thermal resistances depend on the properties of solid and fluid, which are time-independent, while the condensate bulk thermal resistance depends on the condensate thickness, which is time-dependent. There exists intrinsic competition between the interfacial and condensate bulk thermal resistances in timeline and the resultant total thermal resistance determines the condensation intensity for a given vapor-solid temperature difference. We reveal the competition mechanism that the interfacial thermal resistance dominates at the onset of condensation and holds afterwards while the condensate bulk thermal resistance gradually takes over with condensate thickness growing. The weaker the solid-liquid bonding, the later the takeover occurs. This competition mechanism suggests that only when the condensate bulk thermal resistance is reduced after it takes over the domination can the condensation be effectively intensified. We propose a unified theoretical model for the thermal resistance analysis by making dropwise condensation equivalent to filmwise condensation. We further find that near a critical point (contact angle being ca. 153°) the bulk thermal resistance has the least opportunity to take over the domination while away from it the probability increases.

  5. Coupling of Mechanical Behavior of Lithium Ion Cells to Electrochemical-Thermal (ECT) Models for Battery Crush

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chao; Santhanagopalan, Shriram; Pesaran, Ahmad; Sahraei, Elham; Wierzbicki, Tom

    2016-06-14

    Vehicle crashes can lead to crushing of the battery, damaging lithium ion battery cells and causing local shorts, heat generation, and thermal runaway. Simulating all the physics and geometries at the same time is challenging and takes a lot of effort; thus, simplifications are needed. We developed a material model for simultaneously modeling the mechanical-electrochemical-thermal behavior, which predicted the electrical short, voltage drop, and thermal runaway behaviors followed by a mechanical abuse-induced short. The effect of short resistance on the battery cell performance was studied.

  6. Investigation of a Novel Mechanical to Thermal Energy Converter Based on the Inverse Problem of Electric Machines

    Directory of Open Access Journals (Sweden)

    Lei Chen

    2016-07-01

    Full Text Available A novel converter that can directly transform electrical, wind, hydraulic and other types of mechanical energy into thermal energy is presented in this study. First, the thermal energy of the converter is classified and then calculated by a finite element method. The eddy current distribution in the stator of the converter is also discussed. Second, the temperature field of the converter is calculated using a boundary element method. Subsequently, a thermal power–temperature coupled calculation method is presented to calculate the actual thermal power and temperature of the converter. The characteristic curves of the actual thermal power and the increase in water flow temperature are then presented based on the calculation results. Lastly, an experimental system is built, the thermal power and temperature of the converter are measured and the experimental results and the analytical calculations are compared.

  7. Thermal-Conductivity Characterization of Gas Diffusion Layer in Proton Exchange Membrane Fuel Cells and Electrolyzers Under Mechanical Loading

    Science.gov (United States)

    Hamour, M.; Garnier, J. P.; Grandidier, J. C.; Ouibrahim, A.; Martemianov, S.

    2011-05-01

    Accurate information on the temperature field and associated heat transfer rates is particularly important for proton exchange membrane fuel cells (PEMFC) and PEM electrolyzers. An important parameter in fuel cell and electrolyzer performance analysis is the effective thermal conductivity of the gas diffusion layer (GDL) which is a solid porous medium. Usually, this parameter is introduced in modeling and performance analysis without taking into account the dependence of the GDL thermal conductivity λ (in W · m-1 · K-1) on mechanical compression. Nevertheless, mechanical stresses arising in an operating system can change significantly the thermal conductivity and heat exchange. Metrology allowing the characterization of the GDL thermal conductivity as a function of the applied mechanical compression has been developed in this study using the transient hot-wire technique (THW). This method is the best for obtaining standard reference data in fluids, but it is rarely used for thermal-conductivity measurements in solids. The experiments provided with Quintech carbon cloth indicate a strong dependence (up to 300%) of the thermal conductivity λ on the applied mechanical load. The experiments have been provided in the pressure range 0 resistances. For this purpose, measurements with a different number of carbon cloth layers have been provided. The conducted experiments indicate the independence of the measured thermal conductivity on the number of GDL layers and, thus, justify the robustness of the developed method and apparatus for this type of application.

  8. Laser-Induced Thermal-Mechanical Damage Characteristics of Cleartran Multispectral Zinc Sulfide with Temperature-Dependent Properties

    Science.gov (United States)

    Peng, Yajing; Jiang, Yanxue; Yang, Yanqiang

    2015-01-01

    Laser-induced thermal-mechanical damage characteristics of window materials are the focus problems in laser weapon and anti-radiation reinforcement technology. Thermal-mechanical effects and damage characteristics are investigated for cleartran multispectral zinc sulfide (ZnS) thin film window materials irradiated by continuous laser using three-dimensional (3D) thermal-mechanical model. Some temperature-dependent parameters are introduced into the model. The temporal-spatial distributions of temperature and thermal stress are exhibited. The damage mechanism is analyzed. The influences of temperature effect of material parameters and laser intensity on the development of thermal stress and the damage characteristics are examined. The results show, the von Mises equivalent stress along the thickness direction is fluctuant, which originates from the transformation of principal stresses from compressive stress to tensile stress with the increase of depth from irradiated surface. The damage originates from the thermal stress but not the melting. The thermal stress is increased and the damage is accelerated by introducing the temperature effect of parameters or the increasing laser intensity.

  9. Mechanical thermal synthesis of in situ Al based hybrid nanocomposites in Al-Ni-Ti-O system

    Energy Technology Data Exchange (ETDEWEB)

    Dilip, J. John Samuel [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Madras, Tamil Nadu 600036 (India); Reddy, B.S.B. [Universal College of Engineering and Technology, Guntur, Andhra Pradesh 522438 (India); Das, Siddhartha, E-mail: sdas@metal.iitkgp.ernet.i [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur, West Bengal 721302 (India); Das, Karabi [Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur, West Bengal 721302 (India)

    2010-02-04

    Al matrix hybrid nanocomposite is synthesized from a powder blend of Al-12% (wt) NiO-15% (wt) TiO{sub 2} by combined mechanical and thermal activation (mechanical thermal synthesis). The powder blends are mechanically activated by high energy ball milling followed by consolidation and thermal treatment. Milled powders are characterized by differential thermal analysis (DTA), X-ray diffraction (XRD) and electron microscopy. DTA results show the onset reaction temperature to decrease with increase in the milling time. Series of thermal treatments in a wide range of temperatures are performed on the green compacts. The thermally treated samples are then characterized by XRD and electron microscopy. The superior microhardness (1.86-2.25 GPa) of the nanocomposite may be attributed to ultra fine grain size of the Al matrix, and Orowan strengthening from the nanosized reinforcements. Aluminothermic reduction reaction between Al, NiO and TiO{sub 2} is successfully exploited for the synthesis of in situ hybrid nanocomposite by combined mechanical-thermal activation.

  10. Molecular dynamics simulations of highly cross-linked polymer networks: prediction of thermal and mechanical properties

    Science.gov (United States)

    Shenogina, Natalia; Tsige, Mesfin; Mukhopadhyay, Sharmila; Patnaik, Soumya

    2012-02-01

    We use all-atom molecular dynamics (MD) simulations to predict the mechanical and thermal properties of thermosetting polymers. Atomistic simulation is a promising tool which can provide detailed structure-property relationships of densely cross-linked polymer networks. In this work we study the thermo-mechanical properties of thermosetting polymers based on amine curing agents and epoxy resins and have focused on the DGEBA/DETDA epoxy system. At first we describe the modeling approach to construction of realistic all-atom models of densely cross-linked polymer matrices. Subsequently, a series of atomistic simulations was carried out to examine the simulation cell size effect as well as the role of cross-linking density and chain length of the resin strands on thermo-mechanical properties at different temperatures. Two different methods were used to deform the polymer networks. Both static and dynamic approaches to calculating the mechanical properties were considered and the thermo-mechanical properties obtained from our simulations were found in reasonable agreement with experimental values.

  11. Mechanism of thermal decomposition of a pesticide for safety concerns: Case of Mancozeb

    Energy Technology Data Exchange (ETDEWEB)

    Giroud, N. [Laboratoire Gestion des Risques et Environnement, 25, rue de Chemnitz, 68200 Mulhouse (France); TREDI, Service Recherche, Technopole de Nancy-Brabois, 9, avenue de la foret de Haye, 54505 Vandoeuvre-les-Nancy (France); Dorge, S., E-mail: sophie.dorge@uha.fr [Laboratoire Gestion des Risques et Environnement, 25, rue de Chemnitz, 68200 Mulhouse (France); Trouve, G. [Laboratoire Gestion des Risques et Environnement, 25, rue de Chemnitz, 68200 Mulhouse (France)

    2010-12-15

    Thermal decomposition under both air and inert atmospheres of a commercial Mancozeb product was investigated through thermogravimetric analysis and laboratory scale thermal treatment from 20 deg. C to 950 deg. C, with analysis of gaseous and solid products. The aim of this study is the understanding of the thermal degradation mechanisms of a pesticide under different atmospheres and the chemical identification of the solid and gaseous pollutants which can be emitted during warehouse fires and which can constitute a threat for health and environment. Pyrolysis of Mancozeb takes place between 20 deg. C and 950 deg. C and lead essentially to CS{sub 2} and H{sub 2}S emissions with formation at 950 deg. C of MnS and ZnS. Thermal oxidation of Mancozeb under air occurs between 150 deg. C and 950 deg. C with formation of CO, CO{sub 2} and sulphur gases (CS{sub 2} and SO{sub 2}). The first step (155-226 deg. C) is the loss of CS{sub 2} and the formation of ethylene thiourea, ZnS and MnS. The metallic sulphides are oxidized in ZnO and MnSO{sub 4} between 226 deg. C and 650 deg. C (steps 2 and 3). MnSO{sub 4} is then oxidized in Mn{sub 3}O{sub 4} during the last step (step 4) between 650 deg. C and 950 deg. C. At 950 deg. C, carbon recovery is close to 95%. Sulphur recovery is close to 98% with an equal partition between SO{sub 2} and CS{sub 2}.

  12. Effect of thermal cutaneous stimulation on the gastric motor activity: Study of the mechanism of action

    Institute of Scientific and Technical Information of China (English)

    Ahmed Shafik; Ali A Shafik; Olfat El Sibai; Ismail A Shafik

    2008-01-01

    AIM: To investigate the mechanism of action of thermal cutaneous stimulation on the gastric motor inhibition.METHODS: The gastric tone of 33 healthy volunteers (20 men, mean age 36.7 ±8.4 years) was assessed by a barostat system consisting of a balloon-ended tube connected to a strain gauge and air-injection system. The tube was introduced into the stomach and the balloon was inflated with 300 mL of air. The skin temperature was elevated in increments of 3℃ up to 49℃ and the gastric tone was simultaneously assessed by recording the balloon volume variations expressed as the percentage change from the baseline volume. The test was repeated after separate anesthetization of the skin and stomach with lidocaine and after using normal saline instead of lidocaine.RESULTS: Thermal cutaneous stimulation resulted in a significant decrease of gastric tone 61.2% ±10.3% of the mean baseline volume. Mean latency was 25.6 ± 1.2 ms.After 20 min of individual anesthetization of the skin and stomach, thermal cutaneous stimulation produced no significant change in gastric tone.CONCLUSION: Decrease in the gastric tone in response to thermal cutaneous stimulation suggests a reflex relationship which was absent on individual anesthetization of the 2 possible arms of the reflex arc:the skin and the stomach. We call this relationship the "cutaneo-gastric inhibitory reflex". This reflex may have the potential to serve as an investigative tool in the diagnosis of gastric motor disorders, provided further studies are performed in this respect.

  13. Molecular mechanisms of thermal resistance of the insect trypanosomatid Crithidia thermophila

    Science.gov (United States)

    Ishemgulova, Aygul; Butenko, Anzhelika; Kortišová, Lucie; Boucinha, Carolina; Grybchuk-Ieremenko, Anastasiia; Morelli, Karina A.; Tesařová, Martina; Kraeva, Natalya; Grybchuk, Danyil; Pánek, Tomáš; Flegontov, Pavel; Lukeš, Julius; Votýpka, Jan; Pavan, Márcio Galvão; Opperdoes, Fred R.; Spodareva, Viktoria; d'Avila-Levy, Claudia M.; Kostygov, Alexei Yu.

    2017-01-01

    In the present work, we investigated molecular mechanisms governing thermal resistance of a monoxenous trypanosomatid Crithidia luciliae thermophila, which we reclassified as a separate species C. thermophila. We analyzed morphology, growth kinetics, and transcriptomic profiles of flagellates cultivated at low (23°C) and elevated (34°C) temperature. When maintained at high temperature, they grew significantly faster, became shorter, with genes involved in sugar metabolism and mitochondrial stress protection significantly upregulated. Comparison with another thermoresistant monoxenous trypanosomatid, Leptomonas seymouri, revealed dramatic differences in transcription profiles of the two species with only few genes showing the same expression pattern. This disparity illustrates differences in the biology of these two parasites and distinct mechanisms of their thermotolerance, a prerequisite for living in warm-blooded vertebrates. PMID:28328988

  14. Mechanical properties of cables exposed to simultaneous thermal and radiation aging

    Energy Technology Data Exchange (ETDEWEB)

    Jacobus, M.J. (Sandia National Labs., Albuquerque, NM (USA)); Fuehrer, G.F. (Science and Engineering Associates, Inc., Albuquerque, NM (USA))

    1990-01-01

    Sandia National Laboratories is conducting long-term aging research on representative samples of nuclear power plant Class 1E cables. The objectives of this program are to determine the suitability of these cables for extended life (beyond the 40-year design basis) and to assess various cable condition monitoring (CM) techniques for predicting remaining cable life. This paper provides the results of mechanical measurements that were performed on cable specimens cross-linked polyethylene neoprene jackets: chlorinated polyethylene jackets, fiberglass braid jackets, and chlorosulfonated polyethylene jackets aged at relatively mild, simultaneous thermal and radiation exposure conditions for periods of up to nine months. After aging, some of the aged samples, as well as some unaged samples, were exposed to accident gamma radiation at ambient temperature. The mechanical measurements discussed in this paper include tensile strength, ultimate elongation, and compressive modulus. 10 refs., 22 figs., 2 tabs.

  15. Mechanical, Thermal, and Electrical Properties of Graphene-Epoxy Nanocomposites—A Review

    Directory of Open Access Journals (Sweden)

    Rasheed Atif

    2016-08-01

    Full Text Available Monolithic epoxy, because of its brittleness, cannot prevent crack propagation and is vulnerable to fracture. However, it is well established that when reinforced—especially by nano-fillers, such as metallic oxides, clays, carbon nanotubes, and other carbonaceous materials—its ability to withstand crack propagation is propitiously improved. Among various nano-fillers, graphene has recently been employed as reinforcement in epoxy to enhance the fracture related properties of the produced epoxy–graphene nanocomposites. In this review, mechanical, thermal, and electrical properties of graphene reinforced epoxy nanocomposites will be correlated with the topographical features, morphology, weight fraction, dispersion state, and surface functionalization of graphene. The factors in which contrasting results were reported in the literature are highlighted, such as the influence of graphene on the mechanical properties of epoxy nanocomposites. Furthermore, the challenges to achieving the desired performance of polymer nanocomposites are also suggested throughout the article.

  16. Mechanical and Thermal Properties of Muscovite and Density Polyethylene-reinforced and-toughened Polypropylene Composites

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lingyan; WEI Tingting; CHEN Huijie; LAI Weiqiang; BU Junfen

    2009-01-01

    The mechanical and thermal properties of polypropylene(PP)/muscovite/ low-density polyethylene(LDPE)/polypropylenegraftmaleic anhydride(PP-g-MAH)ternary com-posites were investigated.In PP matrix,muscovite,LDPE,and PP-g-MAH were added as strength-ening agent,toughening agent,and compatibilizer,respectively.The effects of dosages of the added materials were analyzed.The experimental results show that the optimum recipe of PP/muscovite/LDPE/PP-g-MAH composites is 100/10/6/20(mass ratio).Compared with the pure PP, the mechanical properties of PP/muscovite/LDPE/PP-g-MAH composites,including notched impact strength,Rockwell hardness and flexural strength,are improved.Although tensile strength is slightly decreased,they have better toughness.Filled with muscovite,the heat-resistance and heat-decompostion of the composites are improved.

  17. Effect of thermal processing on microstructure and mechanical properties of AZ80 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The influences of deformation temperature and deformation degree on the mierostructure and mechanical properties of AZ80 magnesium alloy were investigated by the adoption of isothermal plain strain compression experiment. The results show that thermal compression processing can refine the grain size and the tensile strength of all the deformed AZ80 magnesium alloys is increased to the maximum of 320 MPa. With the increasing of deformation temperature, the tensile strength decreases; with the increasing of the deformation degree, the tensile strength increases significantly in the temperature range of 200-300 ℃ and becomes stable at temperature higher than 300 ℃. During the compression processing of AZ80 magnesium alloys, at lower temperature(300 ℃), dynamic reerystallization is complete and refined grainstrengthening is dominant, leading to little effect of deformation degree on mechanical properties.

  18. Failure of EB-PVD Thermal Barrier Coatings Subjected to Thermo-Mechanical Loading

    Institute of Scientific and Technical Information of China (English)

    CHEN Chen; ZHANG Chun-xia; GUO Hong-bo; GONG Sheng-kai; ZHANG Yue

    2006-01-01

    Thermal barrier coatings (TBCs) were developed to protect metallic blades and vanes working in turbo-engines. The two-layered structure TBCs, consisting of NiCoCrAlY bond coat and yttria stabilized zirconia (YSZ), were deposited on a cylinder of superalloy substrate by the electron beam-physical vapor deposition (EB-PVD). The failure mechanism of the TBCs was investigated with a thermo-mechanical fatigue testing system under the service condition similar to that for turbine blades. Non-destructive evaluation of the coated specimens was conducted through the impedance spectroscopy. It is found that the crack initiation mainly takes place on the top coat at the edge of the heated zones.

  19. Waveguide mechanism and design of thermal contact resistance at metal rheologic interface

    Institute of Scientific and Technical Information of China (English)

    胡仕成; 黄明辉; 李晓谦; 钟掘

    2003-01-01

    The main factors and their varied disciplines affecting the heat transfer at the metal rheologic interface were studied from the waveguide mechanism of heat transfer of electrons and phonons, guiding the design of thermal contact resistance through studying the microscale mechanism of heat transfer at the interface. The results show that electron has stronger quantum tunneling effect when the thickness of oxide film is smaller than de Broglie wavelength of electron and the heat conduction of oxide film produces microscale effect. The thickness and nature of oxide film dominate the heat transfer at the metal rheologic interface. The main means to design the interface contact conductance are to control the formation of oxide film as well as the process of machining of roller surface and lubrication of interface.

  20. The influence of mechanical vibrations on microstructure of Ni-based thermally sprayed-fused coatings

    Directory of Open Access Journals (Sweden)

    Jelena ŠKAMAT

    2013-12-01

    Full Text Available The influence of mechanical vibrations on microstructure and properties of Ni-based thermally sprayed and fused coatings deposited on a steel substrate has been studied. Self-fluxing powder with about 73% Ni was used as a sprayed material. As-sprayed coatings were refused using conventional flame technique and with introducing of mechanical vibrations. In result coatings with quite complicated microstructure were obtained. During investigation of coatings by different methods it was found that vibratory treatment really influences the solidified microstructure. It was found that vibrations promote densimetric movement of hard particles up - towards a surface with forming of thicker so-called “hard-inclusions-free” layer near interface. Some tendency was noted that coatings, remelted under vibrations, showed better corrosion and high-temperature oxidation resistance in comparison with coatings created without vibrational treatment during solidification.