Technique for Calculating the Bulk Modulus
NASA Astrophysics Data System (ADS)
Greshnyakov, V. A.; Belenkov, E. A.
2014-10-01
A comparative analysis of different techniques for calculating the bulk modulus of solid bodies has been performed. A new technique for calculating the bulk modulus is proposed which is especially adapted for theoretical calculations of the elastic properties of crystals. The new technique makes it possible to calculate the values of bulk moduli at high pressures with greater accuracy.
Prediction of the Viscoelastic Bulk Modulus
NASA Astrophysics Data System (ADS)
Guo, Jiaxi; Simon, Sindee
2010-03-01
The bulk and shear viscoelastic responses for several materials appear to arise from the same molecular mechanisms at short times, i.e., Andrade creep where the KWW beta parameter is approximately 0.3. If this is indeed the case, prediction and placement of the bulk viscoelastic response can be made simply by knowing the limiting elastic and rubbery bulk moduli and the viscoelastic shear response. The proposed methodology, which uses only easily measured functions, is considerably less time- and labor-intensive than direct measurement of the viscoelastic bulk modulus. Here we investigate this hypothesis and compare the calculated viscoelastic bulk responses for several materials to existing data in the literature.
Pressure derivatives of the bulk modulus
NASA Astrophysics Data System (ADS)
Hofmeister, A. M.
1991-12-01
Simple relations between the first (or second) pressure derivative of the bulk modulus and first (or second) thermal Grüneisen parameter γTh (or qTh) are derived from equations that relate KT(P) to vibrational frequencies Vi as a function of pressure for cubic structures or those that have only one nearest neighbor distance, by assuming that the mode Grüneisen parameters, γi = -∂ ln vi/∂ ln V, are approximately equal. The free volume equation results, which holds within experimental uncertainties for about 70% for solids meeting the symmetry requirements. Agreement is poor for compounds with the rutile structure, which have the largest range of γi observed. Another result is a three-parameter equation of state, KoK″o = (5/3 - K'o)2 - (5/3 - K'o)qTh(0) - (K'o - 1)2. All available experimental determinations of K″o are bracketed by the spectroscopic limits for qTh. Use of the average value of zero for qTh (or qTh calculated from other thermodynamic parameters) gives the proper sign for K″o and nearly the same values as experiment, suggesting that this approximate equation can be used predictively. The equations involving K″o and K'o are probably valid for any structure, if the γi are roughly equal, although this most likely occurs for solids that compress nearly isotropically. The new formula, with qTh of zero, give values similar to that obtained from the Vinet-Ferrante-Rose-Smith equation at low K'o gives the same values as the Birch-Murnaghan (third-order finite strain) equation near K'o of 4, and gives nearly equal values as the Grover-Getting-Kennedy equation of state at high K'o. Physically reasonable positive values of K″o as K'o approaches zero are obtained only from the new equation of state and that of Vinet et al. Comparison of the new equation of state with third-order finite strain suggests that the latter is also likely to be incorrect at high K'o and thus should be cautiously applied to V(P) for liquids.
Zero-temperature bulk modulus of alpha-plutonium
NASA Astrophysics Data System (ADS)
Ledbetter, H.; Migliori, A.; Betts, J.; Harrington, S.; El-Khatib, S.
2005-05-01
Using resonant-ultrasound spectroscopy, we measured alpha-plutonium’s bulk modulus B between 298 and 18K . Fitting the measurements to an Einstein-oscillator-based function gave the zero-temperature bulk modulus Bo=70.9GPa . We compare our measurement with numerous previous measurements and with numerous theoretical estimates ranging from 41to227GPa . From 0to300K , B(T) is regular and smooth, evincing no phase transition (electronic, magnetic, structural). The bulk modulus decreases to 54.4GPa , about 30%, a very large change compared with typical materials. We attribute this large decrease to electron localization during warming. High-temperature dB/dT yields a Gruneisen parameter γ=5.1 , too high we believe because of temperature-induced electron localization. From the low-temperature elastic constants, averaged in the usual Debye ⟨v-3⟩ manner, we obtain a Debye temperature ΘD=205K .
Optimizing the bulk modulus of low-density cellular networks.
Durand, Marc
2005-07-01
We present an alternative derivation of upper-bounds for the bulk modulus of both two-dimensional and three-dimensional cellular materials. For two-dimensional materials, we recover exactly the expression of the Hashin-Shtrikman (HS) upper-bound in the low-density limit, while for three-dimensional materials we even improve the HS bound. Furthermore, we establish necessary and sufficient conditions on the cellular structure for maximizing the bulk modulus, for a given solid volume fraction. The conditions are found to be exactly those under which the electrical (or thermal) conductivity of the material reaches its maximal value as well. These results provide a set of straightforward criteria allowing us to address the design of optimized cellular materials, and shed light on recent studies of structures with both maximal bulk modulus and maximal conductivity. Finally, we discuss the specific case of spring networks, and analyze the compatibility of the criteria presented here with the geometrical constraints caused by minimization of surface energy in a real foam.
Ab initio study of phase transition and bulk modulus of NaH
Sun Xiaowei; Chen Qifeng; Chen Xiangrong; Cai Lingcang; Jing Fuqian
2011-02-15
The phase transition of NaH from NaCl- to CsCl-type structure is investigated by an ab initio plane-wave pseudopotential density functional theory method with the norm-conserving pseudopotential scheme in the frame of the generalized gradient approximation correction; the isothermal bulk modulus and its first and second pressure derivatives of the NaCl- and CsCl-type structures under high pressure and temperature are obtained through the quasi-harmonic Debye model. The phase transition obtained from the usual condition of equal enthalpies occurs at the pressure of 32 GPa, which is consistent with the experimental and other calculated values. Through the quasi-harmonic Debye model, in which the phononic effects are considered, the dependences of cell volume V and lattice constant a on temperature T at zero pressure, the isothermal bulk modulus B{sub 0} and its pressure derivatives B{sub 0}'and B{sub 0}'' on pressure P along isotherms 0, 300, and 600 K, are also successfully obtained. -- The isothermal bulk modulus B{sub T}, adiabatic bulk modulus B{sub S}, primitive cell volume V, and lattice constant a of an NaH with an NaCl-type structure as a function temperature T at zero pressure. When T<100 K, B nearly keeps constant; when T>100 K, B decreases dramatically as T increases. Correspondingly, when T<100 K, the primitive cell volume and lattice parameter of an NaH with an NaCl-type structure have a little change; when T>100 K, the primitive cell volume and lattice parameter changes rapidly as T increases. It is the rapid volume or lattice parameter variation that makes the bulk modulus B rapidly decrease. Display Omitted Research highlights: The transition phase of an NaH from NaCl to CsCl structure has been investigated. The relationship between B and T for an NaH at zero pressure has been given. The B{sub T} and its pressure derivatives of an NaH at high pressure have been obtained.
Structure and bulk modulus of high-strength boron compounds
Lundstroem, T.
1997-10-01
The structures and homogeneity ranges of B{sub 6}O{sub 1-x} and B{sub 12}S{sub 2-x} were studied using Rietveld analysis of powder X ray patterns. The oxygen content of boron suboxide decreases with temperature in the range 1250-1450{degrees}C. Stoichiometric boron suboxide cannot be prepared from amorphous or {alpha}-rh boron and B{sub 2}O{sub 3} at ambient pressure. Significantly higher pressures are required. The boron subsulfide was found to be stable from B{sub 12}S{sub <1} to B{sub 12}S{sub 1.3} at 1400-1600{degrees}C. Semiempirical bulk modulus calculations are reported for hard icosahedral boron-rich compounds and diamond-like tetrahedrally coordinated boron compounds. In connection with this the structure of diamond-like B{sub 2}O is discussed.
NASA Astrophysics Data System (ADS)
Özkan, H.
2014-01-01
The temperature dependence of the bulk modulus of ZrB2 above room temperature was calculated by using the equations by Garai and Laugier (J. Appl. Phys. 101 (2007) p.023514) and Lawson and Ledbetter (Philos Mag. 91 (2011) p.1425). The present calculations involve the accurate data for pressure derivative of the bulk modulus for the Anderson-Grüneisen parameter in addition to the other experimental parameters involved. It is interesting to note that the cited equations derived by different thermodynamic approaches give almost equivalent values for the temperature dependencies of the bulk modulus of ZrB2. The present results for the temperature derivatives of the bulk modulus of ZrB2 vary from -0.016 GPa/K at 300-400 K to -0.022 GPa/K at 1500-1600 K, being in good agreements with the corresponding experimental values.
The bulk modulus and young's modulus of the superconductor Ba sub 2 Cu sub 3 YO sub 7
Block, S.; Piermarini, G.J.; Munro, R.G.; Wong-Ng, W. )
1987-07-01
The isothermal equation of state of the high temperature superconducting ceramic material Ba{sub 2}Cu{sub 3}YO{sub 7} has been determined by measurements in a diamond anvil pressure cell using an energy dispersive x-ray diffraction method. The orthorhombic unit cell lattice parameters (a = 3.8856 {angstrom}, b = 11.6804 {angstrom}, c = 3.8185 {angstrom}) were found to have compressions of (2.0%, 2.3%, 1.1%) respectively over the pressure range from one atmosphere to 10.6 GPa at room temperature. Subsequent equation of state analysis of the approximately linear compression of the volume determined that the isothermal bulk modulus was 196 {plus minus} 17 GPa. Young's modulus was estimated to be 235 {plus minus} 20 GPa assuming that the Poisson's ratio for Ba{sub 2}Cu{sub 3}YO{sub 7} was 0.3 which is typical of many ceramics.
Bulk Modulus of Sc2O3: Ab initio Calculations and Experimental Results
S Barzilai; I Halvey; O Yeheskel
2011-12-31
The bulk modulus of scandia is evaluated by ab initio calculation, based on density functional theory, and compared with bulk modulus measurement on nearly fully dense scandia and with the value attained from the equation of state based on diamond anvil cell measurements. The current results are in the upper range of the bulk moduli results in the literature. The scatter in the literature results might be explained by the differences in the specific volumes of the measured and calculated cases. For the specific volume of 59.65{+-}0.07 {angstrom}{sup 3} the average measured isothermal bulk modulus of scandia from the present study and recent literature results is 188{+-}10 GPa.
Dynamic measurement of bulk modulus of dielectric materials using a microwave phase shift technique
NASA Technical Reports Server (NTRS)
Barker, B. J.; Strand, L. D.
1972-01-01
A microwave Doppler shift technique was developed for measuring the dynamic bulk modulus of dielectric materials such as solid propellants. The system has a demonstrated time resolution on the order of milliseconds and a theoretical spatial resolution of a few microns. Accuracy of the technique is dependent on an accurate knowledge of the wavelength of the microwave in the sample being tested. Such measurement techniques are discussed. Preliminary tests with two solid propellants, one non-aluminized and one containing 16% aluminum, yielded reasonable, reproducible results. It was concluded that with refinements the technique holds promise as a practical means for obtaining accurate dynamic bulk modulus data over a variety of transient conditions.
The inversion method of Matrix mineral bulk modulus based on Gassmann equation
NASA Astrophysics Data System (ADS)
Kai, L.; He, X.; Zhang, Z. H.
2015-12-01
In recent years, seismic rock physics has played an important role in oil and gas exploration. The seismic rock physics model can quantitatively describe the reservoir characteristics, such as lithologic association, pore structure, geological processes and so on. But the classic rock physics models need to determine the background parameter, that is, matrix mineral bulk modulus. An inaccurate inputs greatly influence the prediction reliability. By introducing different rock physics parameters, Gassmann equation is used to derive a reasonable modification. Two forms of Matrix mineral bulk modulus inversion methods including the linear regression method and Self-adapting inversion method are proposed. They effectively solve the value issues of Matrix mineral bulk modulus in different complex parameters conditions. Based on laboratory tests data, compared with the conventional method, the linear regression method is more simple and accurate. Meanwhile Self-adapting inversion method also has higher precision in the known rich rock physics parameters. Consequently, the modulus value was applied to reservoir fluid substitution, porosity inversion and S-wave velocity prediction. The introduction of Matrix mineral modulus base on Gassmann equations can effectively improve the reliability of the fluid impact prediction, and computational efficiency.
Structural relaxation driven increase in elastic modulus for a bulk metallic glass
Arora, Harpreet Singh; Aditya, Ayyagari V.; Mukherjee, Sundeep
2015-01-07
The change in elastic modulus as a function of temperature was investigated for a zirconium-based bulk metallic glass. High temperature nano-indentation was done over a wide temperature range from room temperature to the glass-transition. At higher temperature, there was a transition from inhomogeneous to homogeneous deformation, with a decrease in serrated flow and an increase in creep displacement. Hardness was found to decrease, whereas elastic modulus was found to increase with temperature. The increase in elastic modulus for metallic glass at higher temperature was explained by diffusive rearrangement of atoms resulting in free volume annihilation. This is in contrast to elastic modulus increase with temperature for silicate glasses due to compaction of its open three dimensional coordinated structure without any atomic diffusion.
Using the poker-chip test for determining the bulk modulus of asphalt binders
NASA Astrophysics Data System (ADS)
Motamed, Arash; Bhasin, Amit; Liechti, Kenneth M.
2014-02-01
The properties of asphalt binders strongly influence the overall mechanical response of asphalt mixture composites. A thorough understanding of the mechanistic behavior of asphalt binders is important in order to fully and accurately characterize the behavior of the asphalt mixture. The mechanical properties of the asphalt binder, the matrix in the asphalt mixture composite, are time and temperature dependent and have a lower stiffness compared to the inclusions (aggregate particles). However, computational methods used to model the micromechanics of asphalt mixtures typically assume a constant bulk modulus or Poisson's ratio for asphalt binders. This research investigates the time-dependence of the bulk modulus of asphalt binders. Several approaches for measuring the bulk modulus were explored and the poker-chip geometry was found to be the most suitable one. The boundary value problem for the poker-chip geometry was solved to determine the bulk modulus and Poisson's ratio of asphalt binders as a function of time. The findings from this research improve our understanding of the viscoelastic behavior of asphaltic materials, and also guide important assumptions that are typically made during computational modeling of asphaltic materials.
Why is the bulk modulus of jammed solids and granular packings much larger than the shear modulus?
NASA Astrophysics Data System (ADS)
Zaccone, Alessio; Weaire, Denis
2013-03-01
In granular packings and metallic glasses, the rigidity to compression is much more pronounced than with respect to shear, resulting in the bulk modulus being much larger than the shear modulus. This state of affairs becomes dramatic in marginal jammed solids which are solid-like to compression but not to shear (Ellenbroek, Zeravcic, van Saarloos, van Hecke, EPL 87, 34004 (2009)). For metallic glasses, it was argued by Weaire et al. some time ago (Acta Metall. 19, 779 (1971)) that this effect might be due to the nonaffinity of the particle displacements. These arise because the force acting on a particle upon strain as a result of the strain-induced motion of its neighbors is not balanced in the absence of local order. Hence the particles undergo nonaffine displacements to relax these forces to the expense of the elastic storage energy, leading to lower values of the elastic moduli. Using the nonaffine theory of Zaccone and Scossa-Romano (PRB, 83, 184205 (2011)) we found a conclusive solution to this long standing problem. We show that in packings and related materials the excluded volume between neighbors induces geometric correlations which significantly reduce the nonaffinity under compression but leave the nonaffinity in shear substantially unaltered.
NASA Astrophysics Data System (ADS)
Allen, Philip B.
2015-08-01
The quasiharmonic (QH) approximation uses harmonic vibrational frequencies ωQ ,H(V ) computed at volumes V near V0 where the Born-Oppenheimer (BO) energy Eel(V ) is minimum. When this is used in the harmonic free energy, QH approximation gives a good zeroth order theory of thermal expansion and first-order theory of bulk modulus, where nth-order means smaller than the leading term by ɛn, where ɛ =ℏ ωvib/Eel or kBT /Eel , and Eel is an electronic energy scale, typically 2 to 10 eV. Experiment often shows evidence for next-order corrections. When such corrections are needed, anharmonic interactions must be included. The most accessible measure of anharmonicity is the quasiparticle (QP) energy ωQ(V ,T ) seen experimentally by vibrational spectroscopy. However, this cannot just be inserted into the harmonic free energy FH. In this paper, a free energy is found that corrects the double-counting of anharmonic interactions that is made when F is approximated by FH( ωQ(V ,T ) ) . The term "QP thermodynamics" is used for this way of treating anharmonicity. It enables (n +1 ) -order corrections if QH theory is accurate to order n . This procedure is used to give corrections to the specific heat and volume thermal expansion. The QH formulas for isothermal (BT) and adiabatic (BS) bulk moduli are clarified, and the route to higher-order corrections is indicated.
Temperature Dependence of Interatomic Separation and Bulk Modulus for Alkali Halides
NASA Astrophysics Data System (ADS)
Liu, Quan
2016-07-01
The values of interatomic separation r with the change of temperature T for seven alkali halides have been investigated with the help of an isobaric equation of state. The calculated results are used to predict the values of bulk modulus at different temperatures. The results are compared with the available experimental data and other theoretical results and are further discussed in view of recent research in the field of high temperature physics.
Soft resonator of omnidirectional resonance for acoustic metamaterials with a negative bulk modulus
Jing, Xiaodong; Meng, Yang; Sun, Xiaofeng
2015-01-01
Monopolar resonance is of fundamental importance in the acoustic field. Here, we present the realization of a monopolar resonance that goes beyond the concept of Helmholtz resonators. The balloon-like soft resonator (SR) oscillates omnidirectionally and radiates from all parts of its spherical surface, eliminating the need for a hard wall for the cavity and baffle effects. For airborne sound, such a low-modulus resonator can be made extremely lightweight. Deep subwavelength resonance is achieved when the SR is tuned by adjusting the shell thickness, benefiting from the large density contrast between the shell material and the encapsulated gas. The SR resonates with near-perfect monopole symmetry, as demonstrated by the theoretical and experimental results, which are in excellent agreement. For a lattice of SRs, a band gap occurs and blocks near-total transmission, and the effective bulk modulus exhibits a prominent negative band, while the effective mass density remains unchanged. Our study shows that the SR is suitable for building 3D acoustic metamaterials and provides a basis for constructing left-handed materials as a new means of creating a negative bulk modulus. PMID:26538085
Soft resonator of omnidirectional resonance for acoustic metamaterials with a negative bulk modulus
NASA Astrophysics Data System (ADS)
Jing, Xiaodong; Meng, Yang; Sun, Xiaofeng
2015-11-01
Monopolar resonance is of fundamental importance in the acoustic field. Here, we present the realization of a monopolar resonance that goes beyond the concept of Helmholtz resonators. The balloon-like soft resonator (SR) oscillates omnidirectionally and radiates from all parts of its spherical surface, eliminating the need for a hard wall for the cavity and baffle effects. For airborne sound, such a low-modulus resonator can be made extremely lightweight. Deep subwavelength resonance is achieved when the SR is tuned by adjusting the shell thickness, benefiting from the large density contrast between the shell material and the encapsulated gas. The SR resonates with near-perfect monopole symmetry, as demonstrated by the theoretical and experimental results, which are in excellent agreement. For a lattice of SRs, a band gap occurs and blocks near-total transmission, and the effective bulk modulus exhibits a prominent negative band, while the effective mass density remains unchanged. Our study shows that the SR is suitable for building 3D acoustic metamaterials and provides a basis for constructing left-handed materials as a new means of creating a negative bulk modulus.
NASA Astrophysics Data System (ADS)
Liao, Shu-Zhi; Wang, Xiao-Li; Zhu, Xiang-Ping; Zhang, Chun; Ouyang, Yi-Fang; Zhang, Bang-Wei
2009-08-01
The modified analytic embedded atom method (MAEAM) model and the anharmonic theory are used to study the bulk modulus of f cc Al metal. The result shows that the bulk modulus can be described by a quadratic function of temperature. The result is in good agreement with the experimental data and theoretical results calculated by the first principle calculation etc. This outcome indicates that the temperature dependence of the bulk modulus for f cc Al metal can be academically studied with the MAEAM model combining with the anharmonic theory.
NASA Technical Reports Server (NTRS)
Wu, H. I.; Spence, R. D.; Sharpe, P. J.; Goeschl, J. D.
1985-01-01
The traditional bulk elastic modulus approach to plant cell pressure-volume relations is inconsistent with its definition. The relationship between the bulk modulus and Young's modulus that forms the basis of their usual application to cell pressure-volume properties is demonstrated to be physically meaningless. The bulk modulus describes stress/strain relations of solid, homogeneous bodies undergoing small deformations, whereas the plant cell is best described as a thin-shelled, fluid-filled structure with a polymer base. Because cell walls possess a polymer structure, an alternative method of mechanical analysis is presented using polymer elasticity principles. This initial study presents the groundwork of polymer mechanics as would be applied to cell walls and discusses how the matrix and microfibrillar network induce nonlinear stress/strain relationships in the cell wall in response to turgor pressure. In subsequent studies, these concepts will be expanded to include anisotropic expansion as regulated by the microfibrillar network.
Structure and Bulk Modulus of High-Strength Boron Compounds*1
NASA Astrophysics Data System (ADS)
Lundström, Torsten
1997-10-01
The structures and homogeneity ranges of B6O1-xand B12S2-xwere studied using Rietveld analysis of powder X ray patterns. The oxygen content of boron suboxide decreases with temperature in the range 1250-1450°C. Stoichiometric boron suboxide cannot be prepared from amorphous orα-rh boron and B2O3at ambient pressure. Significantly higher pressures are required. The boron subsulfide was found to be stable from B12S<1to B12S1.3at 1400-1600°C. Semiempirical bulk modulus calculations are reported for hard icosahedral boron-rich compounds and diamond-like tetrahedrally coordinated boron compounds. In connection with this the structure of diamond-like B2O is discussed.
High Bulk Modulus of Ionic Liquid and Effects on Performance of Hydraulic System
Kalb, Roland; Tasner, Tadej
2014-01-01
Over recent years ionic liquids have gained in importance, causing a growing number of scientists and engineers to investigate possible applications for these liquids because of their unique physical and chemical properties. Their outstanding advantages such as nonflammable liquid within a broad liquid range, high thermal, mechanical, and chemical stabilities, low solubility for gases, attractive tribological properties (lubrication), and very low compressibility, and so forth, make them more interesting for applications in mechanical engineering, offering great potential for new innovative processes, and also as a novel hydraulic fluid. This paper focuses on the outstanding compressibility properties of ionic liquid EMIM-EtSO4, a very important physical chemically property when IL is used as a hydraulic fluid. This very low compressibility (respectively, very high Bulk modulus), compared to the classical hydraulic mineral oils or the non-flammable HFDU type of hydraulic fluids, opens up new possibilities regarding its usage within hydraulic systems with increased dynamics, respectively, systems' dynamic responses. PMID:24526900
B4N and Fe3BN nitrides bands structure and theoretical determination of bulk modulus
NASA Astrophysics Data System (ADS)
dos Santos, A. V.
2007-06-01
With the evolution of material science there was some technological evolution as well as the need of finding new links which could be applied to diverse areas of knowledge. Thus, in this article, we study nitrides bands structures which contain boron, in two different stoichiometries Fe3BN and B4N. The choice of these compounds is meant to plan new links and to understand nitrides fundamental state properties facing these new crystalline structures. In order to resolve the compound band structure we used the method of linear Muffin Tin orbital (LMTO), with atomic sphere approximation (ASA). By using this method we obtained the energy of formation as a function of the lattice parameter as one of the results. We find the equilibrium lattice parameter of 6.9755 a.u., for the Fe3BN nitride, and in B4N, we have 6.8589 a.u. We also discuss in this article the charge transference between sites and the influence of pressure on the compound properties, as well as the Bulk modulus that is 239.82 GPa for Fe3BN and 105.48 GPa for B4N. We show the behaviour of the density of states (DOS) of the new band structure found for the proposed crystalline structure Fe3BN, in which the B atom replace the Fe atom in the corner of the structure γ‧- Fe4N.
Tapia, A; Villanueva, C; Peón-Escalante, R; Quintal, R; Medina, J; Peñuñuri, F; Avilés, F
2015-06-01
Dedicated bond force constant and bulk modulus of C n fullerenes (n = 20, 28, 36, 50, 60) are computed using density functional theory (DFT). DFT predicts bond force constants of 611, 648, 675, 686, and 691 N/m, for C20, C28, C36, C50, and C60, respectively, indicating that the bond force constant increases for larger fullerenes. The bulk modulus predicted by DFT increases with decreased fullerene diameter, from 0.874 TPa for C60 to 1.830 TPa for C20. The bond force constants predicted by DFT are then used as an input for finite element analysis (FEA) of the fullerenes, considered as spatial frames in structural models where the bond stiffness is represented by the DFT-computed bond force constant. In agreement with DFT, FEA predicts that smaller fullerenes are stiffer, and underestimates the bulk modulus with respect to DFT. The difference between the FEA and DFT predictions of the bulk modulus decreases as the size of the fullerene increases, from 20.9% difference for C20 to only 4% difference for C60. Thus, it is concluded that knowing the appropriate bond force constant, FEA can be used as a plausible approximation to model the elastic behavior of small fullerenes.
Bolanos, J.A.; Longstreth, D.J.
1984-06-01
Pressure volume curves for Alternanthera philoxeroides (Mart.) Grixeb. (alligator weed) grown in 0 to 400 millimolar NaCl were used to determine water potential (PSI), osmotic potential (psi/sub s/), turgor potential (psi/sub p/) and the bulk elastic modulus (element of) of shoots at different tissue water contents. Values of psi decreased with increasing salinity and tissue PSI was always lower than rhizosphere PSI. The relationship between psi/sub p/ and tissue water content changed because element of increased with salinity. As a results, salt-stressed plants had larger ranges of positive turgor but smaller ranges of tissue water content over which psi/sub p/ was positive. To our knowledge, this is the first report of such a salinity effect on element of in higher plants. These increases in element of with salinity provided a mechanism by which a large difference between plant PSI and rhizosphere PSI, the driving force for water uptake, could be produced with relatively little water loss by the plant. A time-course study of response after salinization to 400 millimolar NaCl showed PSI was constant with 1 day, psi/sub s/ and psi/sub p/ continued to change for 2 to 4 days, and element of continued to change for 4 to 12 days. Changes in element of modified the capacity of alligator weed to maintain a positive water balance and consideration of such changes in other species of higher plants should improve our understanding of salt stress. 24 references, 6 figures.
Bulk Modulus of Spherical Palladium Nanoparticles by Chen-Mobius Lattice Inversion Method
NASA Astrophysics Data System (ADS)
Abdul-Hafidh, Esam
2015-03-01
Palladium is a precious and rare element that belongs to the Platinum group metals (PGMS) with the lowest density and melting point. Numerous uses of Pd in dentistry, medicine and industrial applications attracted considerable investment. Preparation and characterization of palladium nanoparticles have been conducted by many researchers, but very little effort has taken place on the study of Pd physical properties, such as, mechanical, optical, and electrical. In this study, Chen-Mobius lattice inversion method is used to calculate the cohesive energy and modulus of palladium. The method was employed to calculate the cohesive energy by summing over all pairs of atoms within palladium spherical nanoparticles. The modulus is derived from the cohesive energy curve as a function of particles' sizes. The cohesive energy has been calculated using the potential energy function proposed by (Rose et al., 1981). The results are found to be comparable with previous predictions of metallic nanoparticles. This work is supported by the Royal commission at Yanbu- Saudi Arabia.
Oh, Jae Eun; Clark, Simon M.; Wenk, Hans-Rudolf; Monteiro, Paulo J.M.
2012-02-15
Using a diamond anvil cell, 14 A tobermorite, a structural analogue of calcium silicate hydrates (C-S-H), was examined by high-pressure synchrotron X-ray diffraction up to 4.8 GPa under hydrostatic conditions. The bulk modulus of 14 A tobermorite was calculated, K{sub o} = 47 GPa. Comparison of the current results with previous high pressure studies on C-S-H(I) indicates that: (1) the compression behavior of the lattice parameters a and b of 14 A tobermorite and C-S-H(I) are very similar, implying that both materials may have very similar Ca-O layers, and also implying that an introduction of structural defects into the Ca-O layers may not substantially change in-plane incompressibility of the ab plane of 14 A tobermorite; and (2) the bulk modulus values of 14 A tobermorite and C-S-H(I) are dominated by the incompressibility of the lattice parameter c, which is directly related to the interlayer spacing composed of dreierketten silicate chains, interlayer Ca, and water molecules.
NASA Technical Reports Server (NTRS)
Schlosser, Herbert
1992-01-01
In this note we present two expressions relating the cohesive energy, E(sub coh), and the zero pressure isothermal bulk modulus, B(sub 0), of the alkali halides. Ag halides and TI halides, with the nearest neighbor distances, d(sub nn). First, we show that the product E(sub coh)d(sub 0) within families of halide crystals with common crystal structure is to a good approximation constant, with maximum rms deviation of plus or minus 2%. Secondly, we demonstrate that within families of halide crystals with a common cation and common crystal structure the product B(sub 0)d(sup 3.5)(sub nn) is a good approximation constant, with maximum rms deviation of plus or minus 1.36%.
Thermal expansivity, bulk modulus, and melting curve of H2O-ice VII to 20 GPa
NASA Technical Reports Server (NTRS)
Fei, Yingwei; Mao, Ho-Kwang; Hemley, Russell J.
1993-01-01
Equation of state properties of ice VII and fluid H2O at high pressures and temperatures have been studied experimentally from 6 to 20 GPa and 300-700 K. The techniques involve direct measurements of the unit-cell volume of the solid using synchrotron X-ray diffraction with an externally heated diamond-anvil cell. The pressure dependencies of the volume and bulk modulus of ice VII at room temperature are in good agreement with previous synchrotron X-ray studies. The thermal expansivity was determined as a function of pressure and the results fit to a newly proposed phenomenological relation and to a Mie-Gruneisen equation of state formalism. The onset of melting of ice VII was determined directly by X-ray diffraction at a series of pressures and found to be in accord with previous volumetric determinations. Thermodynamic calculations based on the new data are performed to evaluate the range of validity of previously proposed equations of state for fluid water derived from static and shock-wave compression experiments and from simulations.
NASA Astrophysics Data System (ADS)
Sougawa, Masaya; Takarabe, Kenichi; Mori, Yoshihisa; Okada, Taku; Yagi, Takehiko; Kariyazaki, Hiroaki; Sueoka, Koji
2013-02-01
The experimental bulk modulus, B0, of C2N2(CH2) is determined to be 258 ± 3.4 GPa from the analysis of high-pressure (up to 30 GPa) X-ray diffraction patterns obtained using synchrotron radiation. This bulk modulus is 40% lower than that of diamond. At the level of a combined analysis of lattice constants determined experimentally and atomic positions obtained theoretically for the compression behavior of C2N2(CH2), the strength of the C-N single bond is determined to be the same as the C-C single bond in diamond. In other words, the tetrahedral frame of C2N2(CH2) which consists of CN3Cb, where Cb is a bridging carbon, is as hard as diamond. To account for the differing bulk moduli, we infer that the lower bulk modulus in C2N2(CH2) is due to the rotational freedom in the crystal at high pressures.
Thakur, Anil Kashyap, Rajinder; Sharma, Nalini; Ahluwalia, P. K.
2014-04-24
Study of atomic motions in the binary liquid alloys have been studied in terms of dynamical variables like velocity auto correlation, power spectrum and mean square displacement. Elastic constants and isothermal bulk modulus have been calculated to see the effeectiveness of ab-initio pseudopotentials which has been used in this paper. This appraoch is free from the fitting parameters and results obtained using this appraoch have been found very close to the average values.
NASA Technical Reports Server (NTRS)
Schlosser, Herbert; Ferrante, John
1989-01-01
The previous work of Schlosser and Ferrante (1988) on universality in solids is extended to the study of liquid metals. As in the case of solids, to a good approximation, in the absence of phase transitions, plots of the logarithm of the reduced-pressure function H, of the reduced-isothermal-bulk-modulus function b, and of the reduced-sound-velocity function v are all linear in 1-X. Finally, it is demonstrated that ln(Cp/C/v) is also linear in 1-X, where X = (V/V/0/)exp 1/3), and V(0) is the volume at zero pressure.
NASA Technical Reports Server (NTRS)
Jacobson, B. O.; Vinet, P.
1986-01-01
Two pressure chambers, for compression experiments with liquids from zero to 2.2 GPa pressure, are described. The experimentally measured compressions are then compared to theoretical values given by an isothermal model of equation of state recently introduced for solids. The model describes the pressure and bulk modulus as a function of compression for different types of lubricants with a very high accuracy up to the pressure limit of the high pressure chamber used (2.2 GPa). In addition the influence of temperature on static solidification pressure was found to be a simple function of the thermal expansion of the fluid.
NASA Technical Reports Server (NTRS)
Jacobson, Bo O.; Vinet, Pascal
1987-01-01
Two pressure chambers, for compression experiments with liquids from zero to 2.2 GPa pressure, are described. The experimentally measured compressions are then compared to theoretical values given by an isothermal model of equation of state recently introduced for solids. The model describes the pressure and bulk modulus as a function of compression for different types of lubricants with a very high accuracy up to the pressure limit of the high pressure chamber used (2.2 GPa). In addition the influence of temperature on static solidification pressure was found to be a simple function of the thermal expansion of the fluid.
Bulk Modulus Capacitor Load Cells
Dickey, C.E.
1990-04-01
Measurement of forces present at various locations within the SSC Model Dipole collared coil assembly is of great practical interest to development engineers. Of particular interest are the forces between coils at the parting plane and forces that exist between coils and pole pieces. It is also desired to observe these forces under the various conditions that a magnet will experience such as: during the collaring process, post-collaring, under the influence of cryogens, and during field excitation. A twenty eight thousandths of an inch thick capacitor load cell which utilizes the hydrostatic condition of a stressed plastic dielectric has been designed. These cells are currently being installed on SSC Model Dipoles. The theory, development, and application of these cells will be discussed.
Tran, Fabien; Stelzl, Julia; Blaha, Peter
2016-05-28
A large panel of old and recently proposed exchange-correlation functionals belonging to rungs 1 to 4 of Jacob's ladder of density functional theory are tested (with and without a dispersion correction term) for the calculation of the lattice constant, bulk modulus, and cohesive energy of solids. Particular attention will be paid to the functionals MGGA_MS2 [J. Sun et al., J. Chem. Phys. 138, 044113 (2013)], mBEEF [J. Wellendorff et al., J. Chem. Phys. 140, 144107 (2014)], and SCAN [J. Sun et al., Phys. Rev. Lett. 115, 036402 (2015)] which are meta-generalized gradient approximations (meta-GGA) and are developed with the goal to be universally good. Another goal is also to determine for which semilocal functionals and groups of solids it is beneficial (or not necessary) to use the Hartree-Fock exchange or a dispersion correction term. It is concluded that for strongly bound solids, functionals of the GGA, i.e., rung 2 of Jacob's ladder, are as accurate as the more sophisticated functionals of the higher rungs, while it is necessary to use dispersion corrected functionals in order to expect at least meaningful results for weakly bound solids. If results for finite systems are also considered, then the meta-GGA functionals are overall clearly superior to the GGA functionals.
NASA Astrophysics Data System (ADS)
Tran, Fabien; Stelzl, Julia; Blaha, Peter
2016-05-01
A large panel of old and recently proposed exchange-correlation functionals belonging to rungs 1 to 4 of Jacob's ladder of density functional theory are tested (with and without a dispersion correction term) for the calculation of the lattice constant, bulk modulus, and cohesive energy of solids. Particular attention will be paid to the functionals MGGA_MS2 [J. Sun et al., J. Chem. Phys. 138, 044113 (2013)], mBEEF [J. Wellendorff et al., J. Chem. Phys. 140, 144107 (2014)], and SCAN [J. Sun et al., Phys. Rev. Lett. 115, 036402 (2015)] which are meta-generalized gradient approximations (meta-GGA) and are developed with the goal to be universally good. Another goal is also to determine for which semilocal functionals and groups of solids it is beneficial (or not necessary) to use the Hartree-Fock exchange or a dispersion correction term. It is concluded that for strongly bound solids, functionals of the GGA, i.e., rung 2 of Jacob's ladder, are as accurate as the more sophisticated functionals of the higher rungs, while it is necessary to use dispersion corrected functionals in order to expect at least meaningful results for weakly bound solids. If results for finite systems are also considered, then the meta-GGA functionals are overall clearly superior to the GGA functionals.
Tran, Fabien; Stelzl, Julia; Blaha, Peter
2016-05-28
A large panel of old and recently proposed exchange-correlation functionals belonging to rungs 1 to 4 of Jacob's ladder of density functional theory are tested (with and without a dispersion correction term) for the calculation of the lattice constant, bulk modulus, and cohesive energy of solids. Particular attention will be paid to the functionals MGGA_MS2 [J. Sun et al., J. Chem. Phys. 138, 044113 (2013)], mBEEF [J. Wellendorff et al., J. Chem. Phys. 140, 144107 (2014)], and SCAN [J. Sun et al., Phys. Rev. Lett. 115, 036402 (2015)] which are meta-generalized gradient approximations (meta-GGA) and are developed with the goal to be universally good. Another goal is also to determine for which semilocal functionals and groups of solids it is beneficial (or not necessary) to use the Hartree-Fock exchange or a dispersion correction term. It is concluded that for strongly bound solids, functionals of the GGA, i.e., rung 2 of Jacob's ladder, are as accurate as the more sophisticated functionals of the higher rungs, while it is necessary to use dispersion corrected functionals in order to expect at least meaningful results for weakly bound solids. If results for finite systems are also considered, then the meta-GGA functionals are overall clearly superior to the GGA functionals. PMID:27250292
Wang Jingyang; Zhou Yanchun; Lin Zhijun; Liao Ting
2005-08-01
We have investigated the electronic structure, chemical bonding, and equations of state of Zr{sub 2}Al{sub 3}C{sub 5} by means of the ab initio pseudopotential total energy method. The chemical bonding displays layered characteristics and is similar to that of nanolaminate ternary aluminum carbides Ti{sub 2}AlC and Ti{sub 3}AlC{sub 2}. Zr{sub 2}Al{sub 3}C{sub 5} could be fundamentally described as strong covalent bonding among Al-C-Zr-C-Zr-C-Al atomic chains being interleaved and mirrored by AlC{sub 2} blocks. The interplanar cohesion between covalent atomic chains and AlC{sub 2} blocks is very weak based on first-principles cohesion energy calculations. Inspired by the structure-property relationship of Ti{sub 2}AlC and Ti{sub 3}AlC{sub 2}, it is expected that Zr{sub 2}Al{sub 3}C{sub 5} will have easy machinability, damage tolerance, and oxidation resistance besides the merits of refractory ZrC. Zr{sub 2}Al{sub 3}C{sub 5} has a theoretical bulk modulus of 160 GPa and illustrates elastic anisotropy under pressure below 20 GPa.
Schneider, Jochen M.; Music, Denis; Sun Zhimei
2005-03-15
We have studied the effect of the valence electron concentration, on the bulk modulus and the chemical bonding in Ta{sub 2}AC and Zr{sub 2}AC (A=Al, Si, and P) by means of ab initio calculations. Our equilibrium volume and the hexagonal ratio (c/a) agree well (within 2.7% and 1.2%, respectively) with previously published experimental data for Ta{sub 2}AlC. The bulk moduli of both Ta{sub 2}AC and Zr{sub 2}AC increase as Al is substituted with Si and P by 13.1% and 20.1%, respectively. This can be understood since the substitution is associated with an increased valence electron concentration, resulting in band filling and an extensive increase in cohesion.
NASA Astrophysics Data System (ADS)
Srivastava, Archana; Thakur, Rasna; Gaur, N. K.
2014-04-01
Specific heat (Cp) thermal expansion (α) and Bulk modulus (BT) of lightly doped Rare Earth manganites (La0.3Pr0.7)0.65Ca0.35Mn1-xBxO3 (B3+ = Fe3+,Cr3+,Ga3+,Al3+,Ru4+); (0.3
Xia, L.; Tang, M. B.; Chan, K. C.; Dong, Y. D.
2014-06-14
Gd{sub 55}Al{sub 20}Co{sub 20}Ni{sub 5} bulk metallic glass (BMG) was synthesized by minor Ni substitution for Co in the Gd{sub 55}Al{sub 20}Co{sub 25} BMG in which excellent glass forming ability (GFA) and magneto-caloric effect were reported previously. The Gd{sub 55}Al{sub 20}Ni{sub 20}Co{sub 5} amorphous rod has a similar GFA to the Gd{sub 55}Al{sub 20}Co{sub 25} BMG but exhibits better magnetic properties. The peak value of magnetic entropy change (−ΔS{sub m}{sup peak}) of the Gd{sub 55}Al{sub 20}Co{sub 20}Ni{sub 5} BMG is 9.8 Jkg{sup −1} K{sup −1}. The field dependence of −ΔS{sub m}{sup peak} follows a −ΔS{sub m}{sup peak}∝H{sup 0.85} relationship. The adiabatic temperature rise of the rod is 4.74 K under 5 T and is larger than of other BMGs previously reported. The improved magnetic properties were supposed to be induced by the enhanced interaction between 4f electron in the rare-earth and 3d electron in the transition metal elements by means of a minor Ni substitution for Co.
Heating and cooling in adiabatic mixing process
Zhou Jing; Zou Xubo; Guo Guangcan; Cai Zi
2010-12-15
We study the effect of interaction on the temperature change in the process of adiabatic mixing of two components of Fermi gases using the real-space Bogoliubov-de Gennes method. We find that in the process of adiabatic mixing, the competition between the adiabatic expansion and the attractive interaction makes it possible to cool or heat the system depending on the strength of the interaction and the initial temperature of the system. The changes of the temperature in a bulk system and in a trapped system are investigated.
Isothermal and Adiabatic Measurements.
ERIC Educational Resources Information Center
McNairy, William W.
1996-01-01
Describes the working of the Adiabatic Gas Law Apparatus, a useful tool for measuring the pressure, temperature, and volume of a variety of gases undergoing compressions and expansions. Describes the adaptation of this apparatus to perform isothermal measurements and discusses the theory behind the adiabatic and isothermal processes. (JRH)
Wireless adiabatic power transfer
Rangelov, A.A.; Suchowski, H.; Silberberg, Y.; Vitanov, N.V.
2011-03-15
Research Highlights: > Efficient and robust mid-range wireless energy transfer between two coils. > The adiabatic energy transfer is analogous to adiabatic passage in quantum optics. > Wireless energy transfer is insensitive to any resonant constraints. > Wireless energy transfer is insensitive to noise in the neighborhood of the coils. - Abstract: We propose a technique for efficient mid-range wireless power transfer between two coils, by adapting the process of adiabatic passage for a coherently driven two-state quantum system to the realm of wireless energy transfer. The proposed technique is shown to be robust to noise, resonant constraints, and other interferences that exist in the neighborhood of the coils.
Parallelizable adiabatic gate teleportation
NASA Astrophysics Data System (ADS)
Nakago, Kosuke; Hajdušek, Michal; Nakayama, Shojun; Murao, Mio
2015-12-01
To investigate how a temporally ordered gate sequence can be parallelized in adiabatic implementations of quantum computation, we modify adiabatic gate teleportation, a model of quantum computation proposed by Bacon and Flammia [Phys. Rev. Lett. 103, 120504 (2009), 10.1103/PhysRevLett.103.120504], to a form deterministically simulating parallelized gate teleportation, which is achievable only by postselection. We introduce a twisted Heisenberg-type interaction Hamiltonian, a Heisenberg-type spin interaction where the coordinates of the second qubit are twisted according to a unitary gate. We develop parallelizable adiabatic gate teleportation (PAGT) where a sequence of unitary gates is performed in a single step of the adiabatic process. In PAGT, numeric calculations suggest the necessary time for the adiabatic evolution implementing a sequence of L unitary gates increases at most as O (L5) . However, we show that it has the interesting property that it can map the temporal order of gates to the spatial order of interactions specified by the final Hamiltonian. Using this property, we present a controlled-PAGT scheme to manipulate the order of gates by a control qubit. In the controlled-PAGT scheme, two differently ordered sequential unitary gates F G and G F are coherently performed depending on the state of a control qubit by simultaneously applying the twisted Heisenberg-type interaction Hamiltonians implementing unitary gates F and G . We investigate why the twisted Heisenberg-type interaction Hamiltonian allows PAGT. We show that the twisted Heisenberg-type interaction Hamiltonian has an ability to perform a transposed unitary gate by just modifying the space ordering of the final Hamiltonian implementing a unitary gate in adiabatic gate teleportation. The dynamics generated by the time-reversed Hamiltonian represented by the transposed unitary gate enables deterministic simulation of a postselected event of parallelized gate teleportation in adiabatic
Adiabatic Heating of Contracting Turbulent Fluids
NASA Astrophysics Data System (ADS)
Robertson, Brant; Goldreich, Peter
2012-05-01
Turbulence influences the behavior of many astrophysical systems, frequently by providing non-thermal pressure support through random bulk motions. Although turbulence is commonly studied in systems with constant volume and mean density, turbulent astrophysical gases often expand or contract under the influence of pressure or gravity. Here, we examine the behavior of turbulence in contracting volumes using idealized models of compressed gases. Employing numerical simulations and an analytical model, we identify a simple mechanism by which the turbulent motions of contracting gases "adiabatically heat," experiencing an increase in their random bulk velocities until the largest eddies in the gas circulate over a Hubble time of the contraction. Adiabatic heating provides a mechanism for sustaining turbulence in gases where no large-scale driving exists. We describe this mechanism in detail and discuss some potential applications to turbulence in astrophysical settings.
ADIABATIC HEATING OF CONTRACTING TURBULENT FLUIDS
Robertson, Brant; Goldreich, Peter
2012-05-10
Turbulence influences the behavior of many astrophysical systems, frequently by providing non-thermal pressure support through random bulk motions. Although turbulence is commonly studied in systems with constant volume and mean density, turbulent astrophysical gases often expand or contract under the influence of pressure or gravity. Here, we examine the behavior of turbulence in contracting volumes using idealized models of compressed gases. Employing numerical simulations and an analytical model, we identify a simple mechanism by which the turbulent motions of contracting gases 'adiabatically heat', experiencing an increase in their random bulk velocities until the largest eddies in the gas circulate over a Hubble time of the contraction. Adiabatic heating provides a mechanism for sustaining turbulence in gases where no large-scale driving exists. We describe this mechanism in detail and discuss some potential applications to turbulence in astrophysical settings.
Srivastava, Archana; Thakur, Rasna; Gaur, N. K.
2014-04-24
Specific heat (C{sub p}) thermal expansion (α) and Bulk modulus (B{sub T}) of lightly doped Rare Earth manganites (La{sub 0.3}Pr{sub 0.7}){sub 0.65}Ca{sub 0.35}Mn{sub 1−x}B{sub x}O{sub 3} (B{sup 3+} = Fe{sup 3+},Cr{sup 3+},Ga{sup 3+},Al{sup 3+},Ru4+); (0.3
Adiabatic capture and debunching
Ng, K.Y.; /Fermilab
2012-03-01
In the study of beam preparation for the g-2 experiment, adiabatic debunching and adiabatic capture are revisited. The voltage programs for these adiabbatic processes are derived and their properties discussed. Comparison is made with some other form of adiabatic capture program. The muon g-2 experiment at Fermilab calls for intense proton bunches for the creation of muons. A booster batch of 84 bunches is injected into the Recycler Ring, where it is debunched and captured into 4 intense bunches with the 2.5-MHz rf. The experiment requires short bunches with total width less than 100 ns. The transport line from the Recycler to the muon-production target has a low momentum aperture of {approx} {+-}22 MeV. Thus each of the 4 intense proton bunches required to have an emittance less than {approx} 3.46 eVs. The incoming booster bunches have total emittance {approx} 8.4 eVs, or each one with an emittance {approx} 0.1 eVs. However, there is always emittance increase when the 84 booster bunches are debunched. There will be even larger emittance increase during adiabatic capture into the buckets of the 2.5-MHz rf. In addition, the incoming booster bunches may have emittances larger than 0.1 eVs. In this article, we will concentrate on the analysis of the adiabatic capture process with the intention of preserving the beam emittance as much as possible. At this moment, beam preparation experiment is being performed at the Main Injector. Since the Main Injector and the Recycler Ring have roughly the same lattice properties, we are referring to adiabatic capture in the Main Injector instead in our discussions.
Bacon, Dave; Flammia, Steven T
2009-09-18
The difficulty in producing precisely timed and controlled quantum gates is a significant source of error in many physical implementations of quantum computers. Here we introduce a simple universal primitive, adiabatic gate teleportation, which is robust to timing errors and many control errors and maintains a constant energy gap throughout the computation above a degenerate ground state space. This construction allows for geometric robustness based upon the control of two independent qubit interactions. Further, our piecewise adiabatic evolution easily relates to the quantum circuit model, enabling the use of standard methods from fault-tolerance theory for establishing thresholds.
Adiabatically implementing quantum gates
Sun, Jie; Lu, Songfeng Liu, Fang
2014-06-14
We show that, through the approach of quantum adiabatic evolution, all of the usual quantum gates can be implemented efficiently, yielding running time of order O(1). This may be considered as a useful alternative to the standard quantum computing approach, which involves quantum gates transforming quantum states during the computing process.
Entanglement and adiabatic quantum computation
NASA Astrophysics Data System (ADS)
Ahrensmeier, D.
2006-06-01
Adiabatic quantum computation provides an alternative approach to quantum computation using a time-dependent Hamiltonian. The time evolution of entanglement during the adiabatic quantum search algorithm is studied, and its relevance as a resource is discussed.
Shrinkage, stress, and modulus of dimethacrylate, ormocer, and silorane composites
Bacchi, Atais; Feitosa, Victor Pinheiro; da Silva Fonseca, Andrea Soares Quirino; Cavalcante, Larissa Maria Assad; Silikas, Nikolaos; Schneider, Luis Felipe Jochins
2015-01-01
Purpose: to evaluate the shrinkage, polymerization stress, elastic and bulk modulus resulting from composites formulated by siloranes, 2nd generation ormocers, and dimethacrylates. Materials and Methods: The bonded disc method was used to evaluate volumetric shrinkage. The polymerization stress was evaluated by mean of the Bioman. Cylindrical specimens (5 mm thickness and 6 mm diameter) were submitted to gradual loading. Young's and bulk modulus were obtained from the slope of the stress/strain curve. Data were analyzed using one-way analysis of variance and Tukey's test (5%). Results: Grandio and ormocer showed significant higher elastic and bulk modulus. Silorane presented significant lowest bulk modulus and maximum shrinkage. Ormocer and silorane presented lower values for the maximum rate of shrinkage. Extra-low shrinkage (ELS) composite presented the greatest maximum shrinkage. The higher maximum rate of shrinkage was attained by Grandio and ELS, statistically similar from each other. The silorane showed lower values of maximum stress and maximum rate of stress. The higher values of maximum stress were presented by ELS and Grandio, statistical similar between them. Grandio showed the significantly greatest maximum rate of stress. Conclusion: Silorane showed to promote lower shrinkage/stress among the composites, with the lowest elastic modulus. Ormocer showed lower shrinkage/stress than methacrylates despite of its high modulus. PMID:26430302
Adiabatic topological quantum computing
NASA Astrophysics Data System (ADS)
Cesare, Chris; Landahl, Andrew J.; Bacon, Dave; Flammia, Steven T.; Neels, Alice
2015-07-01
Topological quantum computing promises error-resistant quantum computation without active error correction. However, there is a worry that during the process of executing quantum gates by braiding anyons around each other, extra anyonic excitations will be created that will disorder the encoded quantum information. Here, we explore this question in detail by studying adiabatic code deformations on Hamiltonians based on topological codes, notably Kitaev's surface codes and the more recently discovered color codes. We develop protocols that enable universal quantum computing by adiabatic evolution in a way that keeps the energy gap of the system constant with respect to the computation size and introduces only simple local Hamiltonian interactions. This allows one to perform holonomic quantum computing with these topological quantum computing systems. The tools we develop allow one to go beyond numerical simulations and understand these processes analytically.
Bazzani, A.; Turchetti, G.; Benedetti, C.; Rambaldi, S.; Servizi, G.
2005-06-08
In a high intensity circular accelerator the synchrotron dynamics introduces a slow modulation in the betatronic tune due to the space-charge tune depression. When the transverse motion is non-linear due to the presence of multipolar effects, resonance islands move in the phase space and change their amplitude. This effect introduces the trapping and detrapping phenomenon and a slow diffusion in the phase space. We apply the neo-adiabatic theory to describe this diffusion mechanism that can contribute to halo formation.
Non-adiabatic dark fluid cosmology
Hipólito-Ricaldi, W.S.; Velten, H.E.S.; Zimdahl, W. E-mail: velten@cce.ufes.br
2009-06-01
We model the dark sector of the cosmic substratum by a viscous fluid with an equation of state p = −ζΘ, where Θ is the fluid-expansion scalar and ζ is the coefficient of bulk viscosity for which we assume a dependence ζ∝ρ{sup ν} on the energy density ρ. The homogeneous and isotropic background dynamics coincides with that of a generalized Chaplygin gas with equation of state p = −A/ρ{sup α}. The perturbation dynamics of the viscous model, however, is intrinsically non-adiabatic and qualitatively different from the Chaplygin-gas case. In particular, it avoids short-scale instabilities and/or oscillations which apparently have ruled out unified models of the Chaplygin-gas type. We calculate the matter power spectrum and demonstrate that the non-adiabatic model is compatible with the data from the 2dFGRS and the SDSS surveys. A χ{sup 2}-analysis shows, that for certain parameter combinations the viscous-dark-fluid (VDF) model is well competitive with the ΛCDM model. These results indicate that non-adiabatic unified models can be seen as potential contenders for a General-Relativity-based description of the cosmic substratum.
Geometry of the Adiabatic Theorem
ERIC Educational Resources Information Center
Lobo, Augusto Cesar; Ribeiro, Rafael Antunes; Ribeiro, Clyffe de Assis; Dieguez, Pedro Ruas
2012-01-01
We present a simple and pedagogical derivation of the quantum adiabatic theorem for two-level systems (a single qubit) based on geometrical structures of quantum mechanics developed by Anandan and Aharonov, among others. We have chosen to use only the minimum geometric structure needed for the understanding of the adiabatic theorem for this case.…
Young's modulus of nanoconfined liquids?
Khan, Shah Haidar; Hoffmann, Peter Manfred
2016-07-01
In material science, bioengineering, and biology, thin liquid films and soft matter membranes play an important role in micro-lubrication, ion transport, and fundamental biological processes. Various attempts have been made to characterize the elastic properties, such as Young's modulus, of such films using Hertz theory by incorporating convoluted mathematical corrections. We propose a simple way to extract tip-size independent elastic properties based on stiffness and force measurement through a spherical tip on a flat surface. Using our model, the Young's modulus of nanoconfined, molecularly-thin, layers of a model liquid TEHOS (tetrakis 2-ethylhexoxy silane) and water were determined using a small-amplitude AFM. This AFM can simultaneously measure the stiffness and forces of nanoscale films. While the stiffness scales linearly with the tip radius, the measured Young's modulus essentially remains constant over an order of magnitude variation in the tip radius. The values obtained for the elastic modulus of TEHOS and water films on the basis of our method are significantly lower than the confining surfaces' elastic moduli, in contrast with the uncorrected Hertz model, suggesting that our method can serve as a simple way to compare elastic properties of nanoscale thin films as well as to characterize a variety of soft films. In addition, our results show that the elastic properties (elastic modulus) of nanoconfined liquid films remain fairly independent of increasing confinement. PMID:27060229
Measurement of Young's relaxation modulus using nanoindentation
NASA Astrophysics Data System (ADS)
Huang, Gang; Lu, Hongbing
2006-09-01
In a previous paper (Lu et al., Mechanics of Time-Dependent Materials, 7, 2003, 189 207), we described methods to measure the creep compliance of polymers using Berkovich and spherical indenters by nanoindentation. However, the relaxation modulus is often needed in stress and deformation analysis. It has been well known that the interconversion between creep compliance and relaxation function presents an ill-posed problem, so that converting the creep compliance function to the relaxation function cannot always give accurate results, especially considering that the creep data at short times in nanoindentation are often not reliable, and the overall nanoindentation time is short, typically a few hundred seconds. In this paper, we present methods to measure Young’s relaxation functions directly using nanoindentation. A constant-rate displacement loading history is usually used in nanoindentations. Using viscoelastic contact mechanics, Young’s relaxation modulus is extracted using nanoindentation load-displacement data. Three bulk polymers, Polymethyl Methacrylate (PMMA), Polycarbonate (PC) and Polyurethane (PU), are used in this study. The Young’s relaxation functions measured from the nanoindentation are compared with data measured from conventional tensile and shear tests to evaluate the precision of the methods. A reasonably good agreement has been reached for all these materials for indentation depth higher than a certain value, providing reassurance for these methods for measuring relaxation functions.
Stress Modulus of Cancer Cells
NASA Astrophysics Data System (ADS)
Bonin, Keith; Guthold, Martin; Guo, Xinyi; Sigley, Justin
2012-02-01
Our main goal is to study the different physical and mechanical properties of cells as they advance through different stages of neoplastic transformation from normal to the metastatic state. Since recent reports indicate there is significant ambiguity about how these properties change for different cancer cells, we plan to measure these properties for a single line of cells, and to determine whether the changes vary for different cellular components: i.e. whether the change in physical properties is due to a change in the cytoskeleton, the cell membrane, the cytoplasm, or a combination of these elements. Here we expect to present data on the stress modulus of cancer cells at different stages: normal, mortal cancerous, immortal cancerous, and tumorigenic. The cells are Weinberg cell line Human Mammary Epithelial (HME) cells. Atomic force microscope (AFM) probes with different diameters are used to push on the cell membrane to measure the local, regional and global cell stress modulus. Preliminary results on normal HME cells suggests a stress modulus of 1.5 ± 0.8 kPa when pushing with 7 μm spherical probes. We anticipate reporting an improved value for the modulus as well as results for some of the Weinberg cancer cells.
Adiabatic computation: A toy model
NASA Astrophysics Data System (ADS)
Ribeiro, Pedro; Mosseri, Rémy
2006-10-01
We discuss a toy model for adiabatic quantum computation which displays some phenomenological properties expected in more realistic implementations. This model has two free parameters: the adiabatic evolution parameter s and the α parameter, which emulates many-variable constraints in the classical computational problem. The proposed model presents, in the s-α plane, a line of first-order quantum phase transition that ends at a second-order point. The relation between computation complexity and the occurrence of quantum phase transitions is discussed. We analyze the behavior of the ground and first excited states near the quantum phase transition, the gap, and the entanglement content of the ground state.
Adiabatic computation: A toy model
Ribeiro, Pedro; Mosseri, Remy
2006-10-15
We discuss a toy model for adiabatic quantum computation which displays some phenomenological properties expected in more realistic implementations. This model has two free parameters: the adiabatic evolution parameter s and the {alpha} parameter, which emulates many-variable constraints in the classical computational problem. The proposed model presents, in the s-{alpha} plane, a line of first-order quantum phase transition that ends at a second-order point. The relation between computation complexity and the occurrence of quantum phase transitions is discussed. We analyze the behavior of the ground and first excited states near the quantum phase transition, the gap, and the entanglement content of the ground state.
Adiabatic evolution of plasma equilibrium
Grad, H.; Hu, P. N.; Stevens, D. C.
1975-01-01
A new theory of plasma equilibrium is introduced in which adiabatic constraints are specified. This leads to a mathematically nonstandard structure, as compared to the usual equilibrium theory, in which prescription of pressure and current profiles leads to an elliptic partial differential equation. Topologically complex configurations require further generalization of the concept of adiabaticity to allow irreversible mixing of plasma and magnetic flux among islands. Matching conditions across a boundary layer at the separatrix are obtained from appropriate conservation laws. Applications are made to configurations with planned islands (as in Doublet) and accidental islands (as in Tokamaks). Two-dimensional, axially symmetric, helically symmetric, and closed line equilibria are included. PMID:16578729
Elementary examples of adiabatic invariance
NASA Astrophysics Data System (ADS)
Crawford, Frank S.
1990-04-01
Simple classical one-dimensional systems subject to adiabatic (gradual) perturbations are examined. The first examples are well known: the adiabatic invariance of the product Eτ of energy E and period τ for the simple pendulum and for the simple harmonic oscillator. Next, the adiabatic invariants of the vertical bouncer are found—a ball bouncing elastically from the floor of a rising elevator having slowly varying velocity and acceleration. These examples lead to consideration of adiabatic invariance for one-dimensional systems with potentials of the form V=axn, with a=a(t) slowly varying in time. Then, the horizontal bouncer is considered—a mass sliding on a smooth floor, bouncing back and forth between two impenetrable walls, one of which is slowly moving. This example is generalized to a particle in a bound state of a general potential with one slowly moving ``turning point.'' Finally, circular motion of a charged particle in a magnetic field slowly varying in time under three different configurations is considered: (a) a free particle in a uniform field; (b) a free particle in a nonuniform ``betatron'' field; and (c) a particle constrained to a circular orbit in a uniform field.
Pressure Oscillations in Adiabatic Compression
ERIC Educational Resources Information Center
Stout, Roland
2011-01-01
After finding Moloney and McGarvey's modified adiabatic compression apparatus, I decided to insert this experiment into my physical chemistry laboratory at the last minute, replacing a problematic experiment. With insufficient time to build the apparatus, we placed a bottle between two thick textbooks and compressed it with a third textbook forced…
Elastic modulus of viral nanotubes
NASA Astrophysics Data System (ADS)
Zhao, Yue; Ge, Zhibin; Fang, Jiyu
2008-09-01
We report an experimental and theoretical study of the radial elasticity of tobacco mosaic virus (TMV) nanotubes. An atomic force microscope tip is used to apply small radial indentations to deform TMV nanotubes. The initial elastic response of TMV nanotubes can be described by finite-element analysis in 5nm indentation depths and Hertz theory in 1.5nm indentation depths. The derived radial Young’s modulus of TMV nanotubes is 0.92±0.15GPa from finite-element analysis and 1.0±0.2GPa from the Hertz model, which are comparable with the reported axial Young’s modulus of 1.1GPa [Falvo , Biophys. J. 72, 1396 (1997)].
Transitionless driving on adiabatic search algorithm
Oh, Sangchul; Kais, Sabre
2014-12-14
We study quantum dynamics of the adiabatic search algorithm with the equivalent two-level system. Its adiabatic and non-adiabatic evolution is studied and visualized as trajectories of Bloch vectors on a Bloch sphere. We find the change in the non-adiabatic transition probability from exponential decay for the short running time to inverse-square decay in asymptotic running time. The scaling of the critical running time is expressed in terms of the Lambert W function. We derive the transitionless driving Hamiltonian for the adiabatic search algorithm, which makes a quantum state follow the adiabatic path. We demonstrate that a uniform transitionless driving Hamiltonian, approximate to the exact time-dependent driving Hamiltonian, can alter the non-adiabatic transition probability from the inverse square decay to the inverse fourth power decay with the running time. This may open up a new but simple way of speeding up adiabatic quantum dynamics.
Studies in Chaotic adiabatic dynamics
Jarzynski, C.
1994-01-01
Chaotic adiabatic dynamics refers to the study of systems exhibiting chaotic evolution under slowly time-dependent equations of motion. In this dissertation the author restricts his attention to Hamiltonian chaotic adiabatic systems. The results presented are organized around a central theme, namely, that the energies of such systems evolve diffusively. He begins with a general analysis, in which he motivates and derives a Fokker-Planck equation governing this process of energy diffusion. He applies this equation to study the {open_quotes}goodness{close_quotes} of an adiabatic invariant associated with chaotic motion. This formalism is then applied to two specific examples. The first is that of a gas of noninteracting point particles inside a hard container that deforms slowly with time. Both the two- and three-dimensional cases are considered. The results are discussed in the context of the Wall Formula for one-body dissipation in nuclear physics, and it is shown that such a gas approaches, asymptotically with time, an exponential velocity distribution. The second example involves the Fermi mechanism for the acceleration of cosmic rays. Explicit evolution equations are obtained for the distribution of cosmic ray energies within this model, and the steady-state energy distribution that arises when this equation is modified to account for the injection and removal of cosmic rays is discussed. Finally, the author re-examines the multiple-time-scale approach as applied to the study of phase space evolution under a chaotic adiabatic Hamiltonian. This leads to a more rigorous derivation of the above-mentioned Fokker-Planck equation, and also to a new term which has relevance to the problem of chaotic adiabatic reaction forces (the forces acting on slow, heavy degrees of freedom due to their coupling to light, fast chaotic degrees).
Adiabatic frequency conversion with a sign flip in the coupling
NASA Astrophysics Data System (ADS)
Hristova, H. S.; Rangelov, A. A.; Montemezzani, G.; Vitanov, N. V.
2016-09-01
Adiabatic frequency conversion is a method recently developed in nonlinear optics [H. Suchowski, D. Oron, A. Arie, and Y. Silberberg, Phys. Rev. A 78, 063821 (2008), 10.1103/PhysRevA.78.063821], using ideas from the technique of rapid adiabatic passage (RAP) via a level crossing in quantum physics. In this method, the coupling coefficients are constant and the phase mismatch is chirped adiabatically. In this work, we propose another method for adiabatic frequency conversion, in which the phase mismatch is constant and the coupling is a pulse-shaped function with a sign flip (i.e., a phase step of π ) at its maximum. Compared to the RAP method, our technique has comparable efficiency but it is simpler to implement for it only needs two bulk crystals with opposite χ(2 ) nonlinearity. Moreover, because our technique requires constant nonzero frequency mismatch and has zero conversion efficiency on exact frequency matching, it can be used as a frequency filter.
Adiabatic freezing of long-range quantum correlations in spin chains
NASA Astrophysics Data System (ADS)
Shekhar Dhar, Himadri; Rakshit, Debraj; Sen(De, Aditi; Sen, Ujjwal
2016-06-01
We consider a process to create quasi-long-range quantum discord between the non-interacting end spins of a quantum spin chain, with the end spins weakly coupled to the bulk of the chain. The process is not only capable of creating long-range quantum correlation but the latter remains frozen, when certain weak end-couplings are adiabatically varied below certain thresholds. We term this phenomenon as adiabatic freezing of quantum correlation. We observe that the freezing is robust to moderate thermal fluctuations and is intrinsically related to the cooperative properties of the quantum spin chain. In particular, we find that the energy gap of the system remains frozen for these adiabatic variations, and moreover, considering the end spins as probes, we show that the interval of freezing can detect the anisotropy transition in quantum XY spin chains. Importantly, the adiabatic freezing of long-range quantum correlations can be simulated with contemporary experimental techniques.
NASA Astrophysics Data System (ADS)
Li, Dafa
2016-05-01
The adiabatic theorem was proposed about 90 years ago and has played an important role in quantum physics. The quantitative adiabatic condition constructed from eigenstates and eigenvalues of a Hamiltonian is a traditional tool to estimate adiabaticity and has proven to be the necessary and sufficient condition for adiabaticity. However, recently the condition has become a controversial subject. In this paper, we list some expressions to estimate the validity of the adiabatic approximation. We show that the quantitative adiabatic condition is invalid for the adiabatic approximation via the Euclidean distance between the adiabatic state and the evolution state. Furthermore, we deduce general necessary and sufficient conditions for the validity of the adiabatic approximation by different definitions.
High elastic modulus polymer electrolytes
Balsara, Nitash Pervez; Singh, Mohit; Eitouni, Hany Basam; Gomez, Enrique Daniel
2013-10-22
A polymer that combines high ionic conductivity with the structural properties required for Li electrode stability is useful as a solid phase electrolyte for high energy density, high cycle life batteries that do not suffer from failures due to side reactions and dendrite growth on the Li electrodes, and other potential applications. The polymer electrolyte includes a linear block copolymer having a conductive linear polymer block with a molecular weight of at least 5000 Daltons, a structural linear polymer block with an elastic modulus in excess of 1.times.10.sup.7 Pa and an ionic conductivity of at least 1.times.10.sup.-5 Scm.sup.-1. The electrolyte is made under dry conditions to achieve the noted characteristics.
Predicting graded young modulus values of Ti alloys modified by ion implantation.
Hassan, M H Mohamed
2004-05-01
There has been, and is still, concern about the high elastic modulus of Ti alloys compared to bone. Any reduction in the Young's modulus value of the implant is expected to enhance stress redistribution to the adjacent bone tissues, minimize stress shielding and eventually prolong device lifetime. Dynamic Monte Carlo simulation is used to predict the gradual reduction in Young's modulus values between the bulk of Ti alloys and the modified surface layers due to Ca ion implantation. The simulation can be used as a screening step when applying new alloys and/or coatings.
Adiabatic Wankel type rotary engine
NASA Technical Reports Server (NTRS)
Kamo, R.; Badgley, P.; Doup, D.
1988-01-01
This SBIR Phase program accomplished the objective of advancing the technology of the Wankel type rotary engine for aircraft applications through the use of adiabatic engine technology. Based on the results of this program, technology is in place to provide a rotor and side and intermediate housings with thermal barrier coatings. A detailed cycle analysis of the NASA 1007R Direct Injection Stratified Charge (DISC) rotary engine was performed which concluded that applying thermal barrier coatings to the rotor should be successful and that it was unlikely that the rotor housing could be successfully run with thermal barrier coatings as the thermal stresses were extensive.
Adiabatic processes in monatomic gases
NASA Astrophysics Data System (ADS)
Carrera-Patiño, Martin E.
1988-08-01
A kinetic model is used to predict the temperature evolution of a monatomic ideal gas undergoing an adiabatic expansion or compression at a constant finite rate, and it is then generalized to treat real gases. The effects of interatomic forces are considered, using as examples the gas with the square-well potential and the van der Waals gas. The model is integrated into a Carnot cycle operating at a finite rate to compare the efficiency's rate-dependent behavior with the reversible result. Limitations of the model, rate penalties, and their importance are discussed.
Adiabatic preparation of Floquet condensates
NASA Astrophysics Data System (ADS)
Heinisch, Christoph; Holthaus, Martin
2016-10-01
We argue that a Bose-Einstein condensate can be transformed into a Floquet condensate, that is, into a periodically time-dependent many-particle state possessing the coherence properties of a mesoscopically occupied single-particle Floquet state. Our reasoning is based on the observation that the denseness of the many-body system's quasienergy spectrum does not necessarily obstruct effectively adiabatic transport. Employing the idealized model of a driven bosonic Josephson junction, we demonstrate that only a small amount of Floquet entropy is generated when a driving force with judiciously chosen frequency and maximum amplitude is turned on smoothly.
On the question of adiabatic invariants
NASA Astrophysics Data System (ADS)
Mitropol'Skii, Iu. A.
Some aspects of the construction of adiabadic invariants for dynamic systems with a single degree of freedom are discussed. Adiabatic invariants are derived using classical principles and the method proposed by Djukic (1981). The discussion covers an adiabatic invariant for a dynamic system with slowly varying parameters; derivation of an expression for an adiabatic invariant by the Djukic method for a second-order equation with a variable mass; and derivation of an expression for the adiabatic invariant for a nearly integrable differential equation.
NASA Astrophysics Data System (ADS)
Li, Ming; Zhao, Aiwu; Jiang, Rui; Wang, Dapeng; Li, Da; Guo, Hongyan; Tao, Wenyu; Gan, Zibao; Zhang, Maofeng
2011-02-01
We studied the influence of the elastic modulus on the gecko-inspired dry adhesion by regulating the elastic modulus of bulk polyurethane combined with changing the size of microarrays. Segmented polyurethane (PU) was utilized to fabricate micro arrays by the porous polydimethyl siloxane (PDMS) membrane molding method. The properties of the micro arrays, such as the elastic modulus and adhesion, were investigated by Triboindenter. The study demonstrates that bulk surfaces show the highest elastic modulus, with similar values at around 175 MPa and decreasing the arrays radius causes a significant decrease in E, down to 0.62 MPa. The corresponding adhesion experiments show that decrease of the elastic modulus can enhance the adhesion which is consistent with the recent theoretical models.
Degenerate adiabatic perturbation theory: Foundations and applications
NASA Astrophysics Data System (ADS)
Rigolin, Gustavo; Ortiz, Gerardo
2014-08-01
We present details and expand on the framework leading to the recently introduced degenerate adiabatic perturbation theory [Phys. Rev. Lett. 104, 170406 (2010), 10.1103/PhysRevLett.104.170406], and on the formulation of the degenerate adiabatic theorem, along with its necessary and sufficient conditions [given in Phys. Rev. A 85, 062111 (2012), 10.1103/PhysRevA.85.062111]. We start with the adiabatic approximation for degenerate Hamiltonians that paves the way to a clear and rigorous statement of the associated degenerate adiabatic theorem, where the non-Abelian geometric phase (Wilczek-Zee phase) plays a central role to its quantitative formulation. We then describe the degenerate adiabatic perturbation theory, whose zeroth-order term is the degenerate adiabatic approximation, in its full generality. The parameter in the perturbative power-series expansion of the time-dependent wave function is directly associated to the inverse of the time it takes to drive the system from its initial to its final state. With the aid of the degenerate adiabatic perturbation theory we obtain rigorous necessary and sufficient conditions for the validity of the adiabatic theorem of quantum mechanics. Finally, to illustrate the power and wide scope of the methodology, we apply the framework to a degenerate Hamiltonian, whose closed-form time-dependent wave function is derived exactly, and also to other nonexactly solvable Hamiltonians whose solutions are numerically computed.
On a Nonlinear Model in Adiabatic Evolutions
NASA Astrophysics Data System (ADS)
Sun, Jie; Lu, Song-Feng
2016-08-01
In this paper, we study a kind of nonlinear model of adiabatic evolution in quantum search problem. As will be seen here, for this problem, there always exists a possibility that this nonlinear model can successfully solve the problem, while the linear model can not. Also in the same setting, when the overlap between the initial state and the final stare is sufficiently large, a simple linear adiabatic evolution can achieve O(1) time efficiency, but infinite time complexity for the nonlinear model of adiabatic evolution is needed. This tells us, it is not always a wise choice to use nonlinear interpolations in adiabatic algorithms. Sometimes, simple linear adiabatic evolutions may be sufficient for using. Supported by the National Natural Science Foundation of China under Grant Nos. 61402188 and 61173050. The first author also gratefully acknowledges the support from the China Postdoctoral Science Foundation under Grant No. 2014M552041
Quantum and classical dynamics in adiabatic computation
NASA Astrophysics Data System (ADS)
Crowley, P. J. D.; Äńurić, T.; Vinci, W.; Warburton, P. A.; Green, A. G.
2014-10-01
Adiabatic transport provides a powerful way to manipulate quantum states. By preparing a system in a readily initialized state and then slowly changing its Hamiltonian, one may achieve quantum states that would otherwise be inaccessible. Moreover, a judicious choice of final Hamiltonian whose ground state encodes the solution to a problem allows adiabatic transport to be used for universal quantum computation. However, the dephasing effects of the environment limit the quantum correlations that an open system can support and degrade the power of such adiabatic computation. We quantify this effect by allowing the system to evolve over a restricted set of quantum states, providing a link between physically inspired classical optimization algorithms and quantum adiabatic optimization. This perspective allows us to develop benchmarks to bound the quantum correlations harnessed by an adiabatic computation. We apply these to the D-Wave Vesuvius machine with revealing—though inconclusive—results.
Ancestrally high elastic modulus of gecko setal beta-keratin.
Peattie, Anne M; Majidi, Carmel; Corder, Andrew; Full, Robert J
2007-12-22
Typical bulk adhesives are characterized by soft, tacky materials with elastic moduli well below 1MPa. Geckos possess subdigital adhesives composed mostly of beta-keratin, a relatively stiff material. Biological adhesives like those of geckos have inspired empirical and modelling research which predicts that even stiff materials can be effective adhesives if they take on a fibrillar form. The molecular structure of beta-keratin is highly conserved across birds and reptiles, suggesting that material properties of gecko setae should be similar to that of beta-keratin previously measured in birds, but this has yet to be established. We used a resonance technique to measure elastic bending modulus in two species of gecko from disparate habitats. We found no significant difference in elastic modulus between Gekko gecko (1.6 GPa +/- 0.15s.e.; n=24 setae) and Ptyodactylus hasselquistii (1.4 GPa +/- 0.15s.e.; n=24 setae). If the elastic modulus of setal keratin is conserved across species, it would suggest a design constraint that must be compensated for structurally, and possibly explain the remarkable variation in gecko adhesive morphology.
Confinement-driven increase in ionomer thin-film modulus.
Page, Kirt A; Kusoglu, Ahmet; Stafford, Christopher M; Kim, Sangcheol; Kline, R Joseph; Weber, Adam Z
2014-05-14
Ion-conductive polymers, or ionomers, are critical materials for a wide range of electrochemical technologies. For optimizing the complex heterogeneous structures in which they occur, there is a need to elucidate the governing structure-property relationships, especially at nanoscale dimensions where interfacial interactions dominate the overall materials response due to confinement effects. It is widely acknowledged that polymer physical behavior can be drastically altered from the bulk when under confinement and the literature is replete with examples thereof. However, there is a deficit in the understanding of ionomers when confined to the nanoscale, although it is apparent from literature that confinement can influence ionomer properties. Herein we show that as one particular ionomer, Nafion, is confined to thin films, there is a drastic increase in the modulus over the bulk value, and we demonstrate that this stiffening can explain previously observed deviations in materials properties such as water transport and uptake upon confinement. Moreover, we provide insight into the underlying confinement-induced stiffening through the application of a simple theoretical framework based on self-consistent micromechanics. This framework can be applied to other polymer systems and assumes that as the polymer is confined the mechanical response becomes dominated by the modulus of individual polymer chains.
Omar, Yamila M.; Al Ghaferi, Amal E-mail: mchiesa@masdar.ac.ae; Chiesa, Matteo E-mail: mchiesa@masdar.ac.ae
2015-07-20
Extensive work has been done in order to determine the bulk elastic modulus of isotropic samples from force curves acquired with atomic force microscopy. However, new challenges are encountered given the development of new materials constructed of one-dimensional anisotropic building blocks, such as carbon nanostructured paper. In the present work, we establish a reliable framework to correlate the elastic modulus values obtained by amplitude modulation atomic force microscope force curves, a nanoscopic technique, with that determined by traditional macroscopic tensile testing. In order to do so, several techniques involving image processing, statistical analysis, and simulations are used to find the appropriate path to understand how macroscopic properties arise from anisotropic nanoscale components, and ultimately, being able to calculate the value of bulk elastic modulus.
Complex shear modulus of a magnetorheological elastomer
NASA Astrophysics Data System (ADS)
Zhou, G. Y.
2004-10-01
In our previous study (Zhou 2003 Smart Mater. Struct. 12 139-46), a technique to extract the field-induced shear modulus through an experiment testing the responded acceleration of a system composed of a magnetorheological elastomer (MRE) and a cuprous mass was introduced. In this paper, we present a different data processing method, based on the Steiglitz-McBride iteration method, to recover the complex shear modulus of an MRE in the frequency domain through the measured force excitation and responded acceleration of the mass in the above-mentioned experiment. The recovered complex shear modulus is analyzed in three ranges of the frequency domain: low-frequency range, moderate-frequency range, and high-frequency range. In the low-frequency range (<250 Hz), the shear modulus is a bell-type curve rising with the applied magnetic field. The average shear modulus over this frequency range is proportional to the applied magnetic field until magnetic saturation is reached. The maximum change of the average shear modulus over this range is found to be above 55% of the zero-field value. The above phenomenon reaffirms that the subquadratic field dependence, which arises from the saturation of the magnetization near the poles of closely spaced pairs of spheres, must be taken into account. In the moderate-frequency range and high-frequency range, the shear modulus is too complex to be analyzed completely by the proposed method. However, some interesting phenomena are also revealed by the proposed method. For instance, the shear modulus increases with frequency at least with the order of a quadratic polynomial, and the shear modulus is not significantly affected by the applied magnetic field.
A geometric criterion for adiabatic chaos
Kaper, T.J. ); Kovacic, G. )
1994-03-01
Chaos in adiabatic Hamiltonian systems is a recent discovery and a pervasive phenomenon in physics. In this work, a geometric criterion is discussed based on the theory of action from classical mechanics to detect the existence of Smale horseshoe chaos in adiabatic systems. It is used to show that generic adiabatic planar Hamiltonian systems exhibit stochastic dynamics in large regions of phase space. To illustrate the method, results are obtained for three problems concerning relativistic particle dynamics, fluid mechanics, and passage through resonance, results which either could not be obtained with existing methods, or which were difficult and analytically impractical to obtain with them.
NASA Technical Reports Server (NTRS)
Kattamis, T. Z.
1984-01-01
Bulk undercooling methods and procedures will first be reviewed. Measurement of various parameters which are necessary to understand the solidification mechanism during and after recalescence will be discussed. During recalescence of levitated, glass-encased large droplets (5 to 8 mm diam) high speed temperature sensing devices coupled with a rapid response oscilloscope are now being used at MIT to measure local thermal behavior in hypoeutectic and eutectic binary Ni-Sn alloys. Dendrite tip velocities were measured by various investigators using thermal sensors or high speed cinematography. The confirmation of the validity of solidification models of bulk-undercooled melts is made difficult by the fineness of the final microstructure, the ultra-rapid evolution of the solidifying system which makes measurements very awkward, and the continuous modification of the microstructure which formed during recalescence because of precipitation, remelting and rapid coarsening.
Simulation of periodically focused, adiabatic thermal beams
Chen, C.; Akylas, T. R.; Barton, T. J.; Field, D. M.; Lang, K. M.; Mok, R. V.
2012-12-21
Self-consistent particle-in-cell simulations are performed to verify earlier theoretical predictions of adiabatic thermal beams in a periodic solenoidal magnetic focusing field [K.R. Samokhvalova, J. Zhou and C. Chen, Phys. Plasma 14, 103102 (2007); J. Zhou, K.R. Samokhvalova and C. Chen, Phys. Plasma 15, 023102 (2008)]. In particular, results are obtained for adiabatic thermal beams that do not rotate in the Larmor frame. For such beams, the theoretical predictions of the rms beam envelope, the conservations of the rms thermal emittances, the adiabatic equation of state, and the Debye length are verified in the simulations. Furthermore, the adiabatic thermal beam is found be stable in the parameter regime where the simulations are performed.
Adiabatic Motion of Fault Tolerant Qubits
NASA Astrophysics Data System (ADS)
Drummond, David Edward
This work proposes and analyzes the adiabatic motion of fault tolerant qubits in two systems as candidates for the building blocks of a quantum computer. The first proposal examines a pair of electron spins in double quantum dots, finding that the leading source of decoherence, hyperfine dephasing, can be suppressed by adiabatic rotation of the dots in real space. The additional spin-orbit effects introduced by this motion are analyzed, simulated, and found to result in an infidelity below the error-correction threshold. The second proposal examines topological qubits formed by Majorana zero modes theorized to exist at the ends of semiconductor nanowires coupled to conventional superconductors. A model is developed to design adiabatic movements of the Majorana bound states to produce entangled qubits. Analysis and simulations indicate that these adiabatic operations can also be used to demonstrate entanglement experimentally by testing Bell's theorem.
General conditions for quantum adiabatic evolution
Comparat, Daniel
2009-07-15
Adiabaticity occurs when, during its evolution, a physical system remains in the instantaneous eigenstate of the Hamiltonian. Unfortunately, existing results, such as the quantum adiabatic theorem based on a slow down evolution [H({epsilon}t),{epsilon}{yields}0], are insufficient to describe an evolution driven by the Hamiltonian H(t) itself. Here we derive general criteria and exact bounds, for the state and its phase, ensuring an adiabatic evolution for any Hamiltonian H(t). As a corollary, we demonstrate that the commonly used condition of a slow Hamiltonian variation rate, compared to the spectral gap, is indeed sufficient to ensure adiabaticity but only when the Hamiltonian is real and nonoscillating (for instance, containing exponential or polynomial but no sinusoidal functions)
Adiabatic Quantum Search in Open Systems
NASA Astrophysics Data System (ADS)
Wild, Dominik S.; Gopalakrishnan, Sarang; Knap, Michael; Yao, Norman Y.; Lukin, Mikhail D.
2016-10-01
Adiabatic quantum algorithms represent a promising approach to universal quantum computation. In isolated systems, a key limitation to such algorithms is the presence of avoided level crossings, where gaps become extremely small. In open quantum systems, the fundamental robustness of adiabatic algorithms remains unresolved. Here, we study the dynamics near an avoided level crossing associated with the adiabatic quantum search algorithm, when the system is coupled to a generic environment. At zero temperature, we find that the algorithm remains scalable provided the noise spectral density of the environment decays sufficiently fast at low frequencies. By contrast, higher order scattering processes render the algorithm inefficient at any finite temperature regardless of the spectral density, implying that no quantum speedup can be achieved. Extensions and implications for other adiabatic quantum algorithms will be discussed.
Experimental demonstration of composite adiabatic passage
NASA Astrophysics Data System (ADS)
Schraft, Daniel; Halfmann, Thomas; Genov, Genko T.; Vitanov, Nikolay V.
2013-12-01
We report an experimental demonstration of composite adiabatic passage (CAP) for robust and efficient manipulation of two-level systems. The technique represents a altered version of rapid adiabatic passage (RAP), driven by composite sequences of radiation pulses with appropriately chosen phases. We implement CAP with radio-frequency pulses to invert (i.e., to rephase) optically prepared spin coherences in a Pr3+:Y2SiO5 crystal. We perform systematic investigations of the efficiency of CAP and compare the results with conventional π pulses and RAP. The data clearly demonstrate the superior features of CAP with regard to robustness and efficiency, even under conditions of weakly fulfilled adiabaticity. The experimental demonstration of composite sequences to support adiabatic passage is of significant relevance whenever a high efficiency or robustness of coherent excitation processes need to be maintained, e.g., as required in quantum information technology.
Adiabatic limits on Riemannian Heisenberg manifolds
Yakovlev, A A
2008-02-28
An asymptotic formula is obtained for the distribution function of the spectrum of the Laplace operator, in the adiabatic limit for the foliation defined by the orbits of an invariant flow on a compact Riemannian Heisenberg manifold. Bibliography: 21 titles.
Adiabatic invariance of oscillons/I -balls
NASA Astrophysics Data System (ADS)
Kawasaki, Masahiro; Takahashi, Fuminobu; Takeda, Naoyuki
2015-11-01
Real scalar fields are known to fragment into spatially localized and long-lived solitons called oscillons or I -balls. We prove the adiabatic invariance of the oscillons/I -balls for a potential that allows periodic motion even in the presence of non-negligible spatial gradient energy. We show that such a potential is uniquely determined to be the quadratic one with a logarithmic correction, for which the oscillons/I -balls are absolutely stable. For slightly different forms of the scalar potential dominated by the quadratic one, the oscillons/I -balls are only quasistable, because the adiabatic charge is only approximately conserved. We check the conservation of the adiabatic charge of the I -balls in numerical simulation by slowly varying the coefficient of logarithmic corrections. This unambiguously shows that the longevity of oscillons/I -balls is due to the adiabatic invariance.
Adiabatic Demagnetization Cooler For Far Infrared Detector
NASA Astrophysics Data System (ADS)
Sato, Akio; Yazawa, Takashi; Yamamoto, Junya
1988-11-01
An small adiabatic demagnetization cooler for an astronomical far infrared detector has been built. Single crystals of manganese ammonium sulphate and chromium potassium alum, were prepared as magnetic substances. The superconducting magnet was indirectly cooled and operated by small current up to 13.3 A, the maximum field being 3.5 T. As a preliminary step, adiabatic demagnetization to zero field was implemented. The lowest temperature obtained was 0.5 K, for 5.0 K initial temperature.
Symmetry of the Adiabatic Condition in the Piston Problem
ERIC Educational Resources Information Center
Anacleto, Joaquim; Ferreira, J. M.
2011-01-01
This study addresses a controversial issue in the adiabatic piston problem, namely that of the piston being adiabatic when it is fixed but no longer so when it can move freely. It is shown that this apparent contradiction arises from the usual definition of adiabatic condition. The issue is addressed here by requiring the adiabatic condition to be…
Hierarchical theory of quantum adiabatic evolution
NASA Astrophysics Data System (ADS)
Zhang, Qi; Gong, Jiangbin; Wu, Biao
2014-12-01
Quantum adiabatic evolution is a dynamical evolution of a quantum system under slow external driving. According to the quantum adiabatic theorem, no transitions occur between nondegenerate instantaneous energy eigenstates in such a dynamical evolution. However, this is true only when the driving rate is infinitesimally small. For a small nonzero driving rate, there are generally small transition probabilities between the energy eigenstates. We develop a classical mechanics framework to address the small deviations from the quantum adiabatic theorem order by order. A hierarchy of Hamiltonians is constructed iteratively with the zeroth-order Hamiltonian being determined by the original system Hamiltonian. The kth-order deviations are governed by a kth-order Hamiltonian, which depends on the time derivatives of the adiabatic parameters up to the kth-order. Two simple examples, the Landau-Zener model and a spin-1/2 particle in a rotating magnetic field, are used to illustrate our hierarchical theory. Our analysis also exposes a deep, previously unknown connection between classical adiabatic theory and quantum adiabatic theory.
Laboratory Measurements of Adiabatic and Isothermal Processes
NASA Astrophysics Data System (ADS)
McNairy, W. W.
1997-04-01
Adiabatic and isothermal measurements on various of gases are made possible by using the Adiabatic Gas Law apparatus made by PASCO Scientific(Much of this work was published by the author in "The Physics Teacher", vol. 34, March 1996, p. 178-80.). By using a computer interface, undergraduates are able to data for monatomic, diatomic and polyatomic gases for both compression and expansion processes. Designed principally to obtain adiabatic data, the apparatus may be easily modified for use in isothermal processes. The various sets of data are imported into a spreadsheet program where fits may be made to the ideal gas law and the adiabatic gas law. Excellent results are obtained for the natural logarithm of pressure versus the natural logarithm of volume for both the isothermal data (expected slope equal to -1 in all cases) and the adiabatic data (slope equal to -1 times the ratio of specific heats for the particular gas). An overview of the lab procedure used at VMI will be presented along with data obtained for several adiabatic and isothermal processes.
Assessment of total efficiency in adiabatic engines
NASA Astrophysics Data System (ADS)
Mitianiec, W.
2016-09-01
The paper presents influence of ceramic coating in all surfaces of the combustion chamber of SI four-stroke engine on working parameters mainly on heat balance and total efficiency. Three cases of engine were considered: standard without ceramic coating, fully adiabatic combustion chamber and engine with different thickness of ceramic coating. Consideration of adiabatic or semi-adiabatic engine was connected with mathematical modelling of heat transfer from the cylinder gas to the cooling medium. This model takes into account changeable convection coefficient based on the experimental formulas of Woschni, heat conductivity of multi-layer walls and also small effect of radiation in SI engines. The simulation model was elaborated with full heat transfer to the cooling medium and unsteady gas flow in the engine intake and exhaust systems. The computer program taking into account 0D model of engine processes in the cylinder and 1D model of gas flow was elaborated for determination of many basic engine thermodynamic parameters for Suzuki DR-Z400S 400 cc SI engine. The paper presents calculation results of influence of the ceramic coating thickness on indicated pressure, specific fuel consumption, cooling and exhaust heat losses. Next it were presented comparisons of effective power, heat losses in the cooling and exhaust systems, total efficiency in function of engine rotational speed and also comparison of temperature inside the cylinder for standard, semi-adiabatic and full adiabatic engine. On the basis of the achieved results it was found higher total efficiency of adiabatic engines at 2500 rpm from 27% for standard engine to 37% for full adiabatic engine.
Graph isomorphism and adiabatic quantum computing
NASA Astrophysics Data System (ADS)
Gaitan, Frank; Clark, Lane
2014-02-01
In the graph isomorphism (GI) problem two N-vertex graphs G and G' are given and the task is to determine whether there exists a permutation of the vertices of G that preserves adjacency and transforms G →G'. If yes, then G and G' are said to be isomorphic; otherwise they are nonisomorphic. The GI problem is an important problem in computer science and is thought to be of comparable difficulty to integer factorization. In this paper we present a quantum algorithm that solves arbitrary instances of GI and which also provides an approach to determining all automorphisms of a given graph. We show how the GI problem can be converted to a combinatorial optimization problem that can be solved using adiabatic quantum evolution. We numerically simulate the algorithm's quantum dynamics and show that it correctly (i) distinguishes nonisomorphic graphs; (ii) recognizes isomorphic graphs and determines the permutation(s) that connect them; and (iii) finds the automorphism group of a given graph G. We then discuss the GI quantum algorithm's experimental implementation, and close by showing how it can be leveraged to give a quantum algorithm that solves arbitrary instances of the NP-complete subgraph isomorphism problem. The computational complexity of an adiabatic quantum algorithm is largely determined by the minimum energy gap Δ (N) separating the ground and first-excited states in the limit of large problem size N ≫1. Calculating Δ (N) in this limit is a fundamental open problem in adiabatic quantum computing, and so it is not possible to determine the computational complexity of adiabatic quantum algorithms in general, nor consequently, of the specific adiabatic quantum algorithms presented here. Adiabatic quantum computing has been shown to be equivalent to the circuit model of quantum computing, and so development of adiabatic quantum algorithms continues to be of great interest.
Elastic modulus of polypyrrole nanotubes: AFM measurement
NASA Astrophysics Data System (ADS)
Cuenot, Stéphane; Demoustier-Champagne, Sophie; Nysten, Bernard
2001-03-01
Polypyrrole nanotubes were electrochemically synthesized within the pores of nanoporous track-etched membranes. After dissolution of the template membrane, they were dispersed on PET membranes. Their tensile elastic modulus was measured by probing them in three points bending using an atomic force microscope. The elastic modulus was deduced from force-curve measurements. In this communication, the effect of the synthesis temperature and of the nanotube diameter will be presented. Especially it will be shown that the elastic modulus strongly increases when the nanotube outer diameter is reduced from 160 nm down to 35 nm. These results are in good agreement with previous results showing that the electrical conductivity of polypyrrole nanotubes increases by more than one order of magnitude when the diameter decreases in the same range. These behaviors could be explained by a larger ratio of well-oriented defect-free polymer chains in smaller tubes.
Measuring shear modulus of individual fibers
NASA Astrophysics Data System (ADS)
Behlow, Herbert; Saini, Deepika; Oliviera, Luciana; Skove, Malcolm; Rao, Apparao
2014-03-01
Fiber technology has advanced to new heights enabling tailored mechanical properties. For reliable fiber applications their mechanical properties must be well characterized at the individual fiber level. Unlike the tensile modulus, which can be well studied in a single fiber, the present indirect and dynamic methods of measuring the shear properties of fibers suffer from various disadvantages such as the interaction between fibers and the influence of damping. In this talk, we introduce a quasi-static method to directly measure the shear modulus of a single micron-sized fiber. Our simple and inexpensive setup yields a shear modulus of 16 and 2 GPa for a single IM7 carbon fiber and a Kevlar fiber, respectively. Furthermore, our setup is also capable of measuring the creep, hysteresis and the torsion coefficient, and examples of these will be presented.
Static shear modulus of electrorheological fluids.
Shi, Lihong; Tam, Wing Yim; Huang, Xianxiang; Sheng, Ping
2006-05-01
We report measurements of the static shear modulus of electrorheological (ER) fluids consisting of water-wetted silica microspheres in silicone oil. A shear-annealing method, using creep-recovery (CR) cycles under an external electric field, is used to enhance ER properties of the fluid. The shear-annealing method enables the silica spheres in the ER fluid to form better aligned and denser column microstructures. A stable state with elastic shear deformation is obtained after a sufficient number of CR cycles, with an optimal combination of stress duration and shear strength. Static shear modulus is obtained by measuring the elastic deformations at different shear stresses for an electric field frequency from 10 to 1000 Hz. A water-bridge model is proposed to explain the enhanced shear modulus.
Accurate adiabatic correction in the hydrogen molecule
NASA Astrophysics Data System (ADS)
Pachucki, Krzysztof; Komasa, Jacek
2014-12-01
A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10-12 at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H2, HD, HT, D2, DT, and T2 has been determined. For the ground state of H2 the estimated precision is 3 × 10-7 cm-1, which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels.
Accurate adiabatic correction in the hydrogen molecule
Pachucki, Krzysztof; Komasa, Jacek
2014-12-14
A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10{sup −12} at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H{sub 2}, HD, HT, D{sub 2}, DT, and T{sub 2} has been determined. For the ground state of H{sub 2} the estimated precision is 3 × 10{sup −7} cm{sup −1}, which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels.
Accurate adiabatic correction in the hydrogen molecule.
Pachucki, Krzysztof; Komasa, Jacek
2014-12-14
A new formalism for the accurate treatment of adiabatic effects in the hydrogen molecule is presented, in which the electronic wave function is expanded in the James-Coolidge basis functions. Systematic increase in the size of the basis set permits estimation of the accuracy. Numerical results for the adiabatic correction to the Born-Oppenheimer interaction energy reveal a relative precision of 10(-12) at an arbitrary internuclear distance. Such calculations have been performed for 88 internuclear distances in the range of 0 < R ⩽ 12 bohrs to construct the adiabatic correction potential and to solve the nuclear Schrödinger equation. Finally, the adiabatic correction to the dissociation energies of all rovibrational levels in H2, HD, HT, D2, DT, and T2 has been determined. For the ground state of H2 the estimated precision is 3 × 10(-7) cm(-1), which is almost three orders of magnitude higher than that of the best previous result. The achieved accuracy removes the adiabatic contribution from the overall error budget of the present day theoretical predictions for the rovibrational levels. PMID:25494728
Elastomer modulus and dielectric strength scaling with sample thickness
NASA Astrophysics Data System (ADS)
Larson, Kent
2015-04-01
Material characteristics such as adhesion and dielectric strength have well recognized dependencies on material thickness. There is disagreement, however, on the scale: the long held dictum that dielectric strength is inversely proportional to the square root of sample thickness has been shown to not always hold true for all materials, nor for all possible thickness regions. In D-EAP applications some studies have postulated a "critical thickness" below which properties show significantly less thickness dependency. While a great deal of data is available for dielectric strength, other properties are not nearly as well documented as samples get thinner. In particular, elastic modulus has been found to increase and elongation to decrease as sample thickness is lowered. This trend can be observed experimentally, but has been rarely reported and certainly does not appear in typical suppliers' product data sheets. Both published and newly generated data were used to study properties such as elastic modulus and dielectric strength vs sample thickness in silicone elastomers. Several theories are examined to explain such behavior, such as the impact of defect size and of common (but not well reported) concentration gradients that occur during elastomer curing that create micron-sized layers at the upper and lower interfaces with divergent properties to the bulk material. As Dielectric Electro-Active Polymer applications strive to lower and lower material thickness, changing mechanical properties must be recognized and taken into consideration for accurate electro-mechanical predictions of performance.
Measuring the Weibull modulus of microscope slides
NASA Technical Reports Server (NTRS)
Sorensen, Carl D.
1992-01-01
The objectives are that students will understand why a three-point bending test is used for ceramic specimens, learn how Weibull statistics are used to measure the strength of brittle materials, and appreciate the amount of variation in the strength of brittle materials with low Weibull modulus. They will understand how the modulus of rupture is used to represent the strength of specimens in a three-point bend test. In addition, students will learn that a logarithmic transformation can be used to convert an exponent into the slope of a straight line. The experimental procedures are explained.
Energy efficiency of adiabatic superconductor logic
NASA Astrophysics Data System (ADS)
Takeuchi, Naoki; Yamanashi, Yuki; Yoshikawa, Nobuyuki
2015-01-01
Adiabatic superconductor logic (ASL), including adiabatic quantum-flux-parametron (AQFP) logic, exhibits high energy efficiency because its bit energy can be decreased below the thermal energy through adiabatic switching operations. In the present paper, we present the general scaling laws of ASL and compare the energy efficiency of ASL with those of other energy-efficient logics. Also, we discuss the minimum energy-delay product (EDP) of ASL at finite temperature. Our study shows that there is a maximum temperature at which the EDP can reach the quantum limit given by ħ/2, which is dependent on the superconductor material and the Josephson junction quality, and that it is reasonable to operate ASL at cryogenic temperatures in order to achieve an EDP that approaches ħ/2.
Adiabatic approximation for the density matrix
NASA Astrophysics Data System (ADS)
Band, Yehuda B.
1992-05-01
An adiabatic approximation for the Liouville density-matrix equation which includes decay terms is developed. The adiabatic approximation employs the eigenvectors of the non-normal Liouville operator. The approximation is valid when there exists a complete set of eigenvectors of the non-normal Liouville operator (i.e., the eigenvectors span the density-matrix space), the time rate of change of the Liouville operator is small, and an auxiliary matrix is nonsingular. Numerical examples are presented involving efficient population transfer in a molecule by stimulated Raman scattering, with the intermediate level of the molecule decaying on a time scale that is fast compared with the pulse durations of the pump and Stokes fields. The adiabatic density-matrix approximation can be simply used to determine the density matrix for atomic or molecular systems interacting with cw electromagnetic fields when spontaneous emission or other decay mechanisms prevail.
Adiabaticity and viscosity in deep mantle convection
NASA Technical Reports Server (NTRS)
Quareni, F.; Yuen, D. A.; Saari, M. R.
1986-01-01
A study has been conducted of steady convection with adiabatic and viscous heating for variable viscosity in the Boussinesq limit using the mean-field theory. A strong nonlinear coupling is found between the thermodynamic constants governing adiabatic heating and the rheological parameters. The range of rheological values for which adiabaticity would occur throughout the mantle has been established. Too large an activation volume, greater than 6 cu cm/mol for the cases examined, would produce unreasonably high temperature at the bottom of the mantle (greater than 6000 K) and superadiabatic gradients, especially in the lower mantle. Radiogenic heating plays a profound role in controlling dynamically mantle temperatures. Present values for the averaged mantle heat production would yield objectionably high temperatures in the lower mantle.
Nonadiabatic exchange dynamics during adiabatic frequency sweeps
NASA Astrophysics Data System (ADS)
Barbara, Thomas M.
2016-04-01
A Bloch equation analysis that includes relaxation and exchange effects during an adiabatic frequency swept pulse is presented. For a large class of sweeps, relaxation can be incorporated using simple first order perturbation theory. For anisochronous exchange, new expressions are derived for exchange augmented rotating frame relaxation. For isochronous exchange between sites with distinct relaxation rate constants outside the extreme narrowing limit, simple criteria for adiabatic exchange are derived and demonstrate that frequency sweeps commonly in use may not be adiabatic with regard to exchange unless the exchange rates are much larger than the relaxation rates. Otherwise, accurate assessment of the sensitivity to exchange dynamics will require numerical integration of the rate equations. Examples of this situation are given for experimentally relevant parameters believed to hold for in-vivo tissue. These results are of significance in the study of exchange induced contrast in magnetic resonance imaging.
On adiabatic invariant in generalized Galileon theories
Ema, Yohei; Jinno, Ryusuke; Nakayama, Kazunori; Mukaida, Kyohei E-mail: jinno@hep-th.phys.s.u-tokyo.ac.jp E-mail: kazunori@hep-th.phys.s.u-tokyo.ac.jp
2015-10-01
We consider background dynamics of generalized Galileon theories in the context of inflation, where gravity and inflaton are non-minimally coupled to each other. In the inflaton oscillation regime, the Hubble parameter and energy density oscillate violently in many cases, in contrast to the Einstein gravity with minimally coupled inflaton. However, we find that there is an adiabatic invariant in the inflaton oscillation regime in any generalized Galileon theory. This adiabatic invariant is useful in estimating the expansion law of the universe and also the particle production rate due to the oscillation of the Hubble parameter.
Spontaneous emission in stimulated Raman adiabatic passage
Ivanov, P. A.; Vitanov, N. V.; Bergmann, K.
2005-11-15
This work explores the effect of spontaneous emission on the population transfer efficiency in stimulated Raman adiabatic passage (STIRAP). The approach uses adiabatic elimination of weakly coupled density matrix elements in the Liouville equation, from which a very accurate analytic approximation is derived. The loss of population transfer efficiency is found to decrease exponentially with the factor {omega}{sub 0}{sup 2}/{gamma}, where {gamma} is the spontaneous emission rate and {omega}{sub 0} is the peak Rabi frequency. The transfer efficiency increases with the pulse delay and reaches a steady value. For large pulse delay and large spontaneous emission rate STIRAP degenerates into optical pumping.
Adiabatic Hyperspherical Analysis of Realistic Nuclear Potentials
NASA Astrophysics Data System (ADS)
Daily, K. M.; Kievsky, Alejandro; Greene, Chris H.
2015-12-01
Using the hyperspherical adiabatic method with the realistic nuclear potentials Argonne V14, Argonne V18, and Argonne V18 with the Urbana IX three-body potential, we calculate the adiabatic potentials and the triton bound state energies. We find that a discrete variable representation with the slow variable discretization method along the hyperradial degree of freedom results in energies consistent with the literature. However, using a Laguerre basis results in missing energy, even when extrapolated to an infinite number of basis functions and channels. We do not include the isospin T = 3/2 contribution in our analysis.
Complexity of the Quantum Adiabatic Algorithm
NASA Technical Reports Server (NTRS)
Hen, Itay
2013-01-01
The Quantum Adiabatic Algorithm (QAA) has been proposed as a mechanism for efficiently solving optimization problems on a quantum computer. Since adiabatic computation is analog in nature and does not require the design and use of quantum gates, it can be thought of as a simpler and perhaps more profound method for performing quantum computations that might also be easier to implement experimentally. While these features have generated substantial research in QAA, to date there is still a lack of solid evidence that the algorithm can outperform classical optimization algorithms.
High strength high modulus ceramic fiber
NASA Technical Reports Server (NTRS)
Fetterolf, R. N.
1972-01-01
Low cost method was developed for producing high strength, high modulus, continuous ceramic oxide fibers. Process transforms inexpensive metallic salts into syrup-like liquids that can be fiberized at room temperatures. Resulting salt fibers are then converted to oxides by calcination at relatively low temperatures.
Effect of swaging on Young׳s modulus of β Ti-33.6Nb-4Sn alloy.
Hanada, Shuji; Masahashi, Naoya; Jung, Taek Kyun; Miyake, Masahiro; Sato, Yutaka S; Kokawa, Hiroyuki
2014-04-01
The effect of swaging on the Young's modulus of β Ti-33.6Nb-4Sn rods was investigated by X-ray diffraction, thermography, microstructural observations, deformation simulator analysis and cyclic tensile deformation. Stress-induced α″ martensite was stabilized by swaging, dependent on the diameter reduction rate during swaging. Thermography and deformation simulator analysis revealed that swaged rods were adiabatically heated, and consequently, stress-induced α″ underwent reverse transformation. Young's modulus, which was measured by the slope of the initial portion of the stress-strain curve, decreased from 56GPa in the hot-forged/quenched rod to 44GPa in the rapidly swaged rod with a high reduction rate and to 45GPa in the gradually swaged rod with a low reduction rate. The tangent modulus, which was measured by the slope of the tangent to any point on the stress-strain curve, decreased with strain even in the linear range of the stress-strain curve of the hot-forged/quenched rod and the rapidly swaged rod, while the tangent modulus remained unchanged for the gradually swaged rod. It was found that Young's moduli in swaged β Ti-33.6Nb-4Sn rods were affected by stabilized α″ martensite. Low Young's modulus of 45GPa and high strength over 800MPa were obtained when the reverse transformation by adiabatic heating was suppressed and the stress-induced α″ was sufficiently stabilized by gradual swaging to a 75% reduction in cross section area.
Towards fault tolerant adiabatic quantum computation.
Lidar, Daniel A
2008-04-25
I show how to protect adiabatic quantum computation (AQC) against decoherence and certain control errors, using a hybrid methodology involving dynamical decoupling, subsystem and stabilizer codes, and energy gaps. Corresponding error bounds are derived. As an example, I show how to perform decoherence-protected AQC against local noise using at most two-body interactions.
Dynamical aspects of an adiabatic piston.
Munakata, T; Ogawa, H
2001-09-01
Dynamical aspects of an adiabatic piston are investigated, based on the mass ratio expansion of the master equation for the piston velocity distribution function. Simple theory for piston motion and relaxation of an ideal gas in a cylinder turns out to reproduce our numerical experiments quantitatively.
Adiabatic reversible compression: a molecular view
NASA Astrophysics Data System (ADS)
Miranda, E. N.
2002-07-01
The adiabatic compression (or expansion) of an ideal gas has been analysed. Using the kinetic theory of gases the usual relation between temperature and volume is obtained, while textbooks follow a thermodynamic approach. In this way we show, once again, the agreement between a macroscopic view (thermodynamics) and a microscopic one (kinetic theory).
Dynamical aspects of an adiabatic piston
NASA Astrophysics Data System (ADS)
Munakata, Toyonori; Ogawa, Hideki
2001-09-01
Dynamical aspects of an adiabatic piston are investigated, based on the mass ratio expansion of the master equation for the piston velocity distribution function. Simple theory for piston motion and relaxation of an ideal gas in a cylinder turns out to reproduce our numerical experiments quantitatively.
Adiabatic Compression in a Fire Syringe.
ERIC Educational Resources Information Center
Hayn, Carl H.; Baird, Scott C.
1985-01-01
Suggests using better materials in fire syringes to obtain more effective results during demonstrations which show the elevation in temperature upon a very rapid (adiabatic) compression of air. Also describes an experiment (using ignition temperatures) which introduces students to the use of thermocouples for high temperature measurements. (DH)
Time dependence of adiabatic particle number
NASA Astrophysics Data System (ADS)
Dabrowski, Robert; Dunne, Gerald V.
2016-09-01
We consider quantum field theoretic systems subject to a time-dependent perturbation, and discuss the question of defining a time-dependent particle number not just at asymptotic early and late times, but also during the perturbation. Naïvely, this is not a well-defined notion for such a nonequilibrium process, as the particle number at intermediate times depends on a basis choice of reference states with respect to which particles and antiparticles are defined, even though the final late-time particle number is independent of this basis choice. The basis choice is associated with a particular truncation of the adiabatic expansion. The adiabatic expansion is divergent, and we show that if this divergent expansion is truncated at its optimal order, a universal time dependence is obtained, confirming a general result of Dingle and Berry. This optimally truncated particle number provides a clear picture of quantum interference effects for perturbations with nontrivial temporal substructure. We illustrate these results using several equivalent definitions of adiabatic particle number: the Bogoliubov, Riccati, spectral function and Schrödinger picture approaches. In each approach, the particle number may be expressed in terms of the tiny deviations between the exact and adiabatic solutions of the Ermakov-Milne equation for the associated time-dependent oscillators.
Apparatus to Measure Adiabatic and Isothermal Processes.
ERIC Educational Resources Information Center
Lamb, D. W.; White, G. M.
1996-01-01
Describes a simple manual apparatus designed to serve as an effective demonstration of the differences between isothermal and adiabatic processes for the general or elementary physics student. Enables students to verify Boyle's law for slow processes and identify the departure from this law for rapid processes and can also be used to give a clear…
Adiabatic Mass Parameters for Spontaneous Fission
Baran, A.; Sheikh, J. A.; Nazarewicz, Witold
2009-01-01
The collective mass tensor derived from the adiabatic time-dependent Hartree-Fock-Bogoliubov theory, perturbative cranking approximation, and the Gaussian overlap approximation to the generator-coordinate method is discussed. Illustrative calculations are carried out for ^{252}Fm using the nuclear density functional theory with Skyrme interaction SkM* and seniority pairing.
Communication: Adiabatic and non-adiabatic electron-nuclear motion: Quantum and classical dynamics
NASA Astrophysics Data System (ADS)
Albert, Julian; Kaiser, Dustin; Engel, Volker
2016-05-01
Using a model for coupled electronic-nuclear motion we investigate the range from negligible to strong non-adiabatic coupling. In the adiabatic case, the quantum dynamics proceeds in a single electronic state, whereas for strong coupling a complete transition between two adiabatic electronic states takes place. It is shown that in all coupling regimes the short-time wave-packet dynamics can be described using ensembles of classical trajectories in the phase space spanned by electronic and nuclear degrees of freedom. We thus provide an example which documents that the quantum concept of non-adiabatic transitions is not necessarily needed if electronic and nuclear motion is treated on the same footing.
Communication: Adiabatic and non-adiabatic electron-nuclear motion: Quantum and classical dynamics.
Albert, Julian; Kaiser, Dustin; Engel, Volker
2016-05-01
Using a model for coupled electronic-nuclear motion we investigate the range from negligible to strong non-adiabatic coupling. In the adiabatic case, the quantum dynamics proceeds in a single electronic state, whereas for strong coupling a complete transition between two adiabatic electronic states takes place. It is shown that in all coupling regimes the short-time wave-packet dynamics can be described using ensembles of classical trajectories in the phase space spanned by electronic and nuclear degrees of freedom. We thus provide an example which documents that the quantum concept of non-adiabatic transitions is not necessarily needed if electronic and nuclear motion is treated on the same footing.
Measurement of Young's modulus of GaAs nanowires growing obliquely on a substrate
Alekseev, P. A. Dunaevskii, M. S.; Stovpyaga, A. V.; Lepsa, M.; Titkov, A. N.
2012-05-15
A convenient and fast method for measuring Young's modulus of semiconductor nanowires obliquely standing on the growth substrate is presented. In this method, the nanowire is elastically bent under the force exerted by the probe of an atomic-force microscope, and the load-unload dependences for the bending of the probe cantilever are recorded. Next, these curves are used to find the bending stiffness of the tilted nanowires, after which, taking into account the nanowire dimensions, Young's modulus is obtained. The implementation of this method is demonstrated for tilted GaAs nanowires growing on a GaAs (111) substrate. Young's modulus is determined by applying finite-element analysis to the problem of the stationary elastic bending of a nanowire taking into account the actual nanowire shape and faceting. It proves that a fairly accurate estimate of Young's modulus can be obtained even if the nanowire shape is approximated by a circular cylinder with a single cross-sectional area. The values of Young's modulus obtained for GaAs nanowires of cubic lattice symmetry are 2 to 3 times smaller than its value for bulk GaAs. This difference is attributed to the presence of stacking faults in the central part of the nanowires.
Young's modulus of peritubular and intertubular human dentin by nano-indentation tests.
Ziskind, Daniel; Hasday, Moran; Cohen, Sidney R; Wagner, H Daniel
2011-04-01
The local Young modulus of dry dentin viewed as a hierarchical composite was measured by nano-indentation using two types of experiments, both in a continuous stiffness measurement mode. First, tests were performed radially along straight lines running across highly mineralized peritubular dentin sections and through less mineralized intertubular dentin areas. These tests revealed a gradual decrease in Young's modulus from the bulk of the peritubular dentin region where modulus values of up to ∼40-42GPa were observed, down to approximately constant values of ∼17GPa in the intertubular dentin region. A second set of nano-indentation experiments was performed on the facets of an irregular polyhedron specimen cut from the intertubular dentin region, so as to probe the modulus of intertubular dentin specimens at different orientations relative to the tubular direction. The results demonstrated that the intertubular dentin region may be considered to be quasi-isotropic, with a slightly higher modulus value (∼22GPa) when the indenting tip axis is parallel to the tubular direction, compared to the values (∼18GPa) obtained when the indenting tip axis is perpendicular to the tubule direction.
The dynamic instability of adiabatic blast waves
NASA Technical Reports Server (NTRS)
Ryu, Dongsu; Vishniac, Ethan T.
1991-01-01
Adiabatic blastwaves, which have a total energy injected from the center E varies as t(sup q) and propagate through a preshock medium with a density rho(sub E) varies as r(sup -omega) are described by a family of similarity solutions. Previous work has shown that adiabatic blastwaves with increasing or constant postshock entropy behind the shock front are susceptible to an oscillatory instability, caused by the difference between the nature of the forces on the two sides of the dense shell behind the shock front. This instability sets in if the dense postshock layer is sufficiently thin. The stability of adiabatic blastwaves with a decreasing postshock entropy is considered. Such blastwaves, if they are decelerating, always have a region behind the shock front which is subject to convection. Some accelerating blastwaves also have such region, depending on the values of q, omega, and gamma where gamma is the adiabatic index. However, since the shock interface stabilizes dynamically induced perturbations, blastwaves become convectively unstable only if the convective zone is localized around the origin or a contact discontinuity far from the shock front. On the other hand, the contact discontinuity of accelerating blastwaves is subject to a strong Rayleigh-Taylor instability. The frequency spectra of the nonradial, normal modes of adiabatic blastwaves have been calculated. The results have been applied to the shocks propagating through supernovae envelopes. It is shown that the metal/He and He/H interfaces are strongly unstable against the Rayleigh-Taylor instability. This instability will induce mixing in supernovae envelopes. In addition the implications of this work for the evolution of planetary nebulae is discussed.
Adiabatic burst evaporation from bicontinuous nanoporous membranes
Ichilmann, Sachar; Rücker, Kerstin; Haase, Markus; Enke, Dirk
2015-01-01
Evaporation of volatile liquids from nanoporous media with bicontinuous morphology and pore diameters of a few 10 nm is an ubiquitous process. For example, such drying processes occur during syntheses of nanoporous materials by sol–gel chemistry or by spinodal decomposition in the presence of solvents as well as during solution impregnation of nanoporous hosts with functional guests. It is commonly assumed that drying is endothermic and driven by non-equilibrium partial pressures of the evaporating species in the gas phase. We show that nearly half of the liquid evaporates in an adiabatic mode involving burst-like liquid-to-gas conversions. During single adiabatic burst evaporation events liquid volumes of up to 107 μm3 are converted to gas. The adiabatic liquid-to-gas conversions occur if air invasion fronts get unstable because of the built-up of high capillary pressures. Adiabatic evaporation bursts propagate avalanche-like through the nanopore systems until the air invasion fronts have reached new stable configurations. Adiabatic cavitation bursts thus compete with Haines jumps involving air invasion front relaxation by local liquid flow without enhanced mass transport out of the nanoporous medium and prevail if the mean pore diameter is in the range of a few 10 nm. The results reported here may help optimize membrane preparation via solvent-based approaches, solution-loading of nanopore systems with guest materials as well as routine use of nanoporous membranes with bicontinuous morphology and may contribute to better understanding of adsorption/desorption processes in nanoporous media. PMID:25926406
High modulus high temperature glass fibers
NASA Technical Reports Server (NTRS)
Bacon, J. F.
1973-01-01
The search for a new high-modulus, high-temperature glass fiber involved the preparation of 500 glass compositions lying in 12 glass fields. These systems consisted primarily of low atomic number oxides and rare-earth oxides. Direct optical measurements of the kinetics of crystallization of the cordierite-rare earth system, for example, showed that the addition of rare-earth oxides decreased the rate of formation of cordierite crystals. Glass samples prepared from these systems proved that the rare-earth oxides made large specific contributions to the Young's modulus of the glasses. The best glasses have moduli greater than 21 million psi, the best glass fibers have moduli greater than 18 million psi, and the best glass fiber-epoxy resin composites have tensile strengths of 298,000 psi, compressive strengths of at least 220,000 psi, flexural strengths of 290,000 psi, and short-beam shear strengths of almost 17,000 psi.
Shear modulus estimation with vibrating needle stimulation.
Orescanin, Marko; Insana, Michael
2010-06-01
An ultrasonic shear wave imaging technique is being developed for estimating the complex shear modulus of biphasic hydropolymers including soft biological tissues. A needle placed in the medium is vibrated along its axis to generate harmonic shear waves. Doppler pulses synchronously track particle motion to estimate shear wave propagation speed. Velocity estimation is improved by implementing a k-lag phase estimator. Fitting shear-wave speed estimates to the predicted dispersion relation curves obtained from two rheological models, we estimate the elastic and viscous components of the complex shear modulus. The dispersion equation estimated using the standard linear solid-body (Zener) model is compared with that from the Kelvin-Voigt model to estimate moduli in gelatin gels in the 50 to 450 Hz shear wave frequency bandwidth. Both models give comparable estimates that agree with independent shear rheometer measurements obtained at lower strain rates. PMID:20529711
Microscopic origin of volume modulus inflation
Cicoli, Michele; Muia, Francesco; Pedro, Francisco Gil
2015-12-21
High-scale string inflationary models are in well-known tension with low-energy supersymmetry. A promising solution involves models where the inflaton is the volume of the extra dimensions so that the gravitino mass relaxes from large values during inflation to smaller values today. We describe a possible microscopic origin of the scalar potential of volume modulus inflation by exploiting non-perturbative effects, string loop and higher derivative perturbative corrections to the supergravity effective action together with contributions from anti-branes and charged hidden matter fields. We also analyse the relation between the size of the flux superpotential and the position of the late-time minimum and the inflection point around which inflation takes place. We perform a detailed study of the inflationary dynamics for a single modulus and a two moduli case where we also analyse the sensitivity of the cosmological observables on the choice of initial conditions.
Higher modulus compositions incorporating particulate rubber
Bauman, B.D.; Williams, M.A.; Bagheri, R.
1997-12-02
Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles. 2 figs.
Higher modulus compositions incorporating particulate rubber
McInnis, E.L.; Bauman, B.D.; Williams, M.A.
1996-04-09
Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles. 2 figs.
Modulus-tunable magnetorheological elastomer microcantilevers
NASA Astrophysics Data System (ADS)
Lee, Dongkyu; Lee, Moonchan; Jung, Namchul; Yun, Minhyuk; Lee, Jungchul; Thundat, Thomas; Jeon, Sangmin
2014-05-01
Modulus-tunable microcantilevers are fabricated from magnetorheological elastomers (MREs) consisting of polydimethylsiloxane and carbonyl iron particles by using a simple sandwich molding method. Depending on the presence or absence of an external magnetic field during curing, isotropic or anisotropic MRE cantilevers are obtained. Randomly distributed particles are present in the polymer matrix of the isotropic microcantilevers, whereas the particles in the anisotropic microcantilevers are aligned in the direction of the magnetic field. The fractional changes in the resonance frequencies of the MRE cantilevers are measured as functions of the magnetic field intensity and the quantity of particles in the matrix. The anisotropic microcantilevers undergo greater changes in frequency than the isotropic microcantilevers when exposed to external magnetic fields, which indicates that larger changes in modulus are induced in the anisotropic microcantilevers. In addition, the dissipation and damping ratios of the MRE microcantilevers are determined by fitting the exponential decays of their deflection amplitudes with time.
Higher modulus compositions incorporating particulate rubber
McInnis, E.L.; Scharff, R.P.; Bauman, B.D.; Williams, M.A.
1995-01-17
Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles. 2 figures.
Higher modulus compositions incorporating particulate rubber
McInnis, Edwin L.; Scharff, Robert P.; Bauman, Bernard D.; Williams, Mark A.
1995-01-01
Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles.
Higher modulus compositions incorporating particulate rubber
Bauman, Bernard D.; Williams, Mark A.; Bagheri, Reza
1997-12-02
Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles.
Higher modulus compositions incorporating particulate rubber
McInnis, Edwin L.; Bauman, Bernard D.; Williams, Mark A.
1996-04-09
Rubber particles, to be used as fillers or extenders for various composite polymer systems, are chlorinated by a gas-solid phase reaction with a chlorine-containing gas. A composite polymer containing the chlorinated rubber fillers or extenders exhibits a higher flexural modulus than if prepared using an unchlorinated rubber filler or extender. Chlorination of the rubber particles is carried out by contacting the finely divided rubber particles with a chlorine-containing gas comprising at least about 5 volume percent chlorine. Advantageously, the chlorine can be diluted with air, nitrogen or other essentially inert gases and may contain minor amounts of fluorine. Improved performance is obtained with nitrogen dilution of the chlorine gas over air dilution. Improved polymer composite systems having higher flexural modulus result from the use of the chlorinated rubber particles as fillers instead of unchlorinated rubber particles.
Shear modulus of neutron star crust
NASA Astrophysics Data System (ADS)
Baiko, D. A.
2011-09-01
The shear modulus of solid neutron star crust is calculated by the thermodynamic perturbation theory, taking into account ion motion. At a given density, the crust is modelled as a body-centred cubic Coulomb crystal of fully ionized atomic nuclei of one type with a uniform charge-compensating electron background. Classic and quantum regimes of ion motion are considered. The calculations in the classic temperature range agree well with previous Monte Carlo simulations. At these temperatures, the shear modulus is given by the sum of a positive contribution due to the static lattice and a negative ∝ T contribution due to the ion motion. The quantum calculations are performed for the first time. The main result is that at low temperatures the contribution to the shear modulus due to the ion motion saturates at a constant value, associated with zero-point ion vibrations. Such behaviour is qualitatively similar to the zero-point ion motion contribution to the crystal energy. The quantum effects may be important for lighter elements at higher densities, where the ion plasma temperature is not entirely negligible compared to the typical Coulomb ion interaction energy. The results of numerical calculations are approximated by convenient fitting formulae. They should be used for precise neutron star oscillation modelling, a rapidly developing branch of stellar seismology.
Adiabatic principles in atom-diatom collisional energy transfer
Hovingh, W.J.
1993-01-01
This work describes the application of numerical methods to the solution of the time dependent Schroedinger equation for non-reactive atom-diatom collisions in which only one of the degrees of freedom has been removed. The basic method involves expanding the wave function in a basis set in two of the diatomic coordinates in a body-fixed frame (with respect to the triatomic complex) and defining the coefficients in that expansion as functions on a grid in the collision coordinate. The wave function is then propagated in time using a split operator method. The bulk of this work is devoted to the application of this formalism to the study of internal rotational predissociation in NeHF, in which quasibound states of the triatom predissociate through the transfer of energy from rotation of the diatom into translational energy in the atom-diatom separation coordinate. The author analyzes the computed time dependent wave functions to calculate the lifetimes for several quasibound states; these are in agreement with time independent quantum calculations using the same potential. Moreover, the time dependent behavior of the wave functions themselves sheds light on the dynamics of the predissociation processes. Finally, the partial cross sections of the products in those processes is determined with multiple exit channels. These show strong selectivity in the orbital angular momentum of the outgoing fragments, which the author explains with an adiabatic channel interpretation of the wave function's dynamics. The author also suggests that the same formalism might profitably be used to investigate the quantum dynamics of [open quotes]quasiresonant vibration-rotation transfer[close quotes], in which remarkably strong propensity rules in certain inelastic atom-diatom collision arise from classical adiabatic invariance theory.
Polystyrene Nanocomposites: Shear and Bulk Rheology and PVT Behavior
NASA Astrophysics Data System (ADS)
Tao, Ran; Simon, Sindee
2013-03-01
One potential strategy to mitigate thermal residual stresses in polymer materials is to reduce the thermal pressure coefficient, a product of the bulk modulus and thermal expansion coefficient. Recent model predictions show that the liquid bulk modulus could decrease by incorporation of well-dispersed spherical nanoparticles into polymer matrix. In this work, the pressure-volume-temperature (PVT) behavior and pressure relaxation response of a 10 wt% silica nanoparticle-filled polystyrene nanocomposite sample are measured using a custom-built pressurizable dilatometer. The glass transition temperature (Tg) is calculated as a function of pressure from the PVT data, and the PVT data are fitted to the Tait equation. Isothermal pressure relaxation experiments are performed in the vicinity of the pressure-dependent Tg, from which the time-dependent bulk modulus is calculated. The temperature dependence of the horizontal shift factors is examined and compared to those obtained from the shear response. In addition, the retardation spectra for the bulk and shear responses are compared and the implications are discussed. The results are consistent with literature prediction indicating that bulk modulus will increase in aggregated nanocomposites system.
Non-adiabatic perturbations in multi-component perfect fluids
Koshelev, N.A.
2011-04-01
The evolution of non-adiabatic perturbations in models with multiple coupled perfect fluids with non-adiabatic sound speed is considered. Instead of splitting the entropy perturbation into relative and intrinsic parts, we introduce a set of symmetric quantities, which also govern the non-adiabatic pressure perturbation in models with energy transfer. We write the gauge invariant equations for the variables that determine on a large scale the non-adiabatic pressure perturbation and the rate of changes of the comoving curvature perturbation. The analysis of evolution of the non-adiabatic pressure perturbation has been made for several particular models.
Adiabatic quantum simulation of quantum chemistry.
Babbush, Ryan; Love, Peter J; Aspuru-Guzik, Alán
2014-10-13
We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions.
Quantum adiabatic evolution with energy degeneracy levels
NASA Astrophysics Data System (ADS)
Zhang, Qi
2016-01-01
A classical-kind phase-space formalism is developed to address the tiny intrinsic dynamical deviation from what is predicted by Wilczek-Zee theorem during quantum adiabatic evolution on degeneracy levels. In this formalism, the Hilbert space and the aggregate of degenerate eigenstates become the classical-kind phase space and a high-dimensional subspace in the phase space, respectively. Compared with the previous analogous study by a different method, the current result is qualitatively different in that the first-order deviation derived here is always perpendicular to the degeneracy subspace. A tripod-scheme Hamiltonian with two degenerate dark states is employed to illustrate the adiabatic deviation with degeneracy levels.
Adiabatic quantum optimization for associative memory recall
Seddiqi, Hadayat; Humble, Travis S.
2014-12-22
Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO). Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are stored in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.
Adiabatic quantum optimization for associative memory recall
Seddiqi, Hadayat; Humble, Travis S.
2014-12-22
Hopfield networks are a variant of associative memory that recall patterns stored in the couplings of an Ising model. Stored memories are conventionally accessed as fixed points in the network dynamics that correspond to energetic minima of the spin state. We show that memories stored in a Hopfield network may also be recalled by energy minimization using adiabatic quantum optimization (AQO). Numerical simulations of the underlying quantum dynamics allow us to quantify AQO recall accuracy with respect to the number of stored memories and noise in the input key. We investigate AQO performance with respect to how memories are storedmore » in the Ising model according to different learning rules. Our results demonstrate that AQO recall accuracy varies strongly with learning rule, a behavior that is attributed to differences in energy landscapes. Consequently, learning rules offer a family of methods for programming adiabatic quantum optimization that we expect to be useful for characterizing AQO performance.« less
Trapped Ion Quantum Computation by Adiabatic Passage
Feng Xuni; Wu Chunfeng; Lai, C. H.; Oh, C. H.
2008-11-07
We propose a new universal quantum computation scheme for trapped ions in thermal motion via the technique of adiabatic passage, which incorporates the advantages of both the adiabatic passage and the model of trapped ions in thermal motion. Our scheme is immune from the decoherence due to spontaneous emission from excited states as the system in our scheme evolves along a dark state. In our scheme the vibrational degrees of freedom are not required to be cooled to their ground states because they are only virtually excited. It is shown that the fidelity of the resultant gate operation is still high even when the magnitude of the effective Rabi frequency moderately deviates from the desired value.
Ramsey numbers and adiabatic quantum computing.
Gaitan, Frank; Clark, Lane
2012-01-01
The graph-theoretic Ramsey numbers are notoriously difficult to calculate. In fact, for the two-color Ramsey numbers R(m,n) with m, n≥3, only nine are currently known. We present a quantum algorithm for the computation of the Ramsey numbers R(m,n). We show how the computation of R(m,n) can be mapped to a combinatorial optimization problem whose solution can be found using adiabatic quantum evolution. We numerically simulate this adiabatic quantum algorithm and show that it correctly determines the Ramsey numbers R(3,3) and R(2,s) for 5≤s≤7. We then discuss the algorithm's experimental implementation, and close by showing that Ramsey number computation belongs to the quantum complexity class quantum Merlin Arthur.
Adiabatic Quantum Simulation of Quantum Chemistry
NASA Astrophysics Data System (ADS)
Babbush, Ryan; Love, Peter J.; Aspuru-Guzik, Alán
2014-10-01
We show how to apply the quantum adiabatic algorithm directly to the quantum computation of molecular properties. We describe a procedure to map electronic structure Hamiltonians to 2-body qubit Hamiltonians with a small set of physically realizable couplings. By combining the Bravyi-Kitaev construction to map fermions to qubits with perturbative gadgets to reduce the Hamiltonian to 2-body, we obtain precision requirements on the coupling strengths and a number of ancilla qubits that scale polynomially in the problem size. Hence our mapping is efficient. The required set of controllable interactions includes only two types of interaction beyond the Ising interactions required to apply the quantum adiabatic algorithm to combinatorial optimization problems. Our mapping may also be of interest to chemists directly as it defines a dictionary from electronic structure to spin Hamiltonians with physical interactions.
Shortcuts to adiabaticity from linear response theory
Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian
2015-10-23
A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. Moreover, with the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. We finally propose a degenerate family of protocols, which facilitates shortcuts to adiabaticity for specific and very short driving times.
Shortcuts to adiabaticity from linear response theory
Acconcia, Thiago V.; Bonança, Marcus V. S.; Deffner, Sebastian
2015-10-23
A shortcut to adiabaticity is a finite-time process that produces the same final state as would result from infinitely slow driving. We show that such shortcuts can be found for weak perturbations from linear response theory. Moreover, with the help of phenomenological response functions, a simple expression for the excess work is found—quantifying the nonequilibrium excitations. For two specific examples, i.e., the quantum parametric oscillator and the spin 1/2 in a time-dependent magnetic field, we show that finite-time zeros of the excess work indicate the existence of shortcuts. We finally propose a degenerate family of protocols, which facilitates shortcuts tomore » adiabaticity for specific and very short driving times.« less
Siphon flows in isolated magnetic flux tubes. II - Adiabatic flows
NASA Technical Reports Server (NTRS)
Montesinos, Benjamin; Thomas, John H.
1989-01-01
This paper extends the study of steady siphon flows in isolated magnetic flux tubes surrounded by field-free gas to the case of adiabatic flows. The basic equations governing steady adiabatic siphon flows in a thin, isolated magnetic flux tube are summarized, and qualitative features of adiabatic flows in elevated, arched flux tubes are discussed. The equations are then cast in nondimensional form and the results of numerical computations of adiabatic siphon flows in arched flux tubes are presented along with comparisons between isothermal and adiabatic flows. The effects of making the interior of the flux tube hotter or colder than the surrounding atmosphere at the upstream footpoint of the arch is considered. In this case, is it found that the adiabatic flows are qualitatively similar to the isothermal flows, with adiabatic cooling producing quantitative differences. Critical flows can produce a bulge point in the rising part of the arch and a concentration of magnetic flux above the bulge point.
Siphon flows in isolated magnetic flux tubes. II. Adiabatic flows
Montesinos, B.; Thomas, J.H.
1989-02-01
This paper extends the study of steady siphon flows in isolated magnetic flux tubes surrounded by field-free gas to the case of adiabatic flows. The basic equations governing steady adiabatic siphon flows in a thin, isolated magnetic flux tube are summarized, and qualitative features of adiabatic flows in elevated, arched flux tubes are discussed. The equations are then cast in nondimensional form and the results of numerical computations of adiabatic siphon flows in arched flux tubes are presented along with comparisons between isothermal and adiabatic flows. The effects of making the interior of the flux tube hotter or colder than the surrounding atmosphere at the upstream footpoint of the arch is considered. In this case, is it found that the adiabatic flows are qualitatively similar to the isothermal flows, with adiabatic cooling producing quantitative differences. Critical flows can produce a bulge point in the rising part of the arch and a concentration of magnetic flux above the bulge point. 15 references.
Computer Code For Turbocompounded Adiabatic Diesel Engine
NASA Technical Reports Server (NTRS)
Assanis, D. N.; Heywood, J. B.
1988-01-01
Computer simulation developed to study advantages of increased exhaust enthalpy in adiabatic turbocompounded diesel engine. Subsytems of conceptual engine include compressor, reciprocator, turbocharger turbine, compounded turbine, ducting, and heat exchangers. Focus of simulation of total system is to define transfers of mass and energy, including release and transfer of heat and transfer of work in each subsystem, and relationship among subsystems. Written in FORTRAN IV.
Adiabatic charging of nickel-hydrogen batteries
NASA Astrophysics Data System (ADS)
Lurie, Chuck; Foroozan, S.; Brewer, Jeff; Jackson, Lorna
1995-02-01
Battery management during prelaunch activities has always required special attention and careful planning. The transition from nickel-cadium to nickel-hydrogen batteries, with their high self discharge rate and lower charge efficiency, as well as longer prelaunch scenarios, has made this aspect of spacecraft battery management even more challenging. The AXAF-I Program requires high battery state of charge at launch. The use of active cooling, to ensure efficient charging, was considered and proved to be difficult and expensive. Alternative approaches were evaluated. Optimized charging, in the absence of cooling, appeared promising and was investigated. Initial testing was conducted to demonstrate the feasibility of the 'Adiabatic Charging' approach. Feasibility was demonstrated and additional testing performed to provide a quantitative, parametric data base. The assumption that the battery is in an adiabatic environment during prelaunch charging is a conservative approximation because the battery will transfer some heat to its surroundings by convective air cooling. The amount is small compared to the heat dissipated during battery overcharge. Because the battery has a large thermal mass, substantial overcharge can occur before the cells get too hot to charge efficiently. The testing presented here simulates a true adiabatic environment. Accordingly the data base may be slightly conservative. The adiabatic charge methodology used in this investigation begins with stabilizing the cell at a given starting temperature. The cell is then fully insulated on all sides. Battery temperature is carefully monitored and the charge terminated when the cell temperature reaches 85 F. Charging has been evaluated with starting temperatures from 55 to 75 F.
Advanced Adiabatic Demagnetization Refrigerators for Continuous Cooling
NASA Technical Reports Server (NTRS)
Chu, Paul C. W.
2004-01-01
The research at Houston was focused on optimizing the design of superconducting magnets for advanced adiabatic demagnetization refrigerators (ADRs), assessing the feasibility of using high temperature superconducting (HTS) magnets in ADRs in the future, and developing techniques to deposit HTS thin and thick films on high strength, low thermal conductivity substrates for HTS magnet leads. Several approaches have been tested for the suggested superconducting magnets.
Random matrix model of adiabatic quantum computing
Mitchell, David R.; Adami, Christoph; Lue, Waynn; Williams, Colin P.
2005-05-15
We present an analysis of the quantum adiabatic algorithm for solving hard instances of 3-SAT (an NP-complete problem) in terms of random matrix theory (RMT). We determine the global regularity of the spectral fluctuations of the instantaneous Hamiltonians encountered during the interpolation between the starting Hamiltonians and the ones whose ground states encode the solutions to the computational problems of interest. At each interpolation point, we quantify the degree of regularity of the average spectral distribution via its Brody parameter, a measure that distinguishes regular (i.e., Poissonian) from chaotic (i.e., Wigner-type) distributions of normalized nearest-neighbor spacings. We find that for hard problem instances - i.e., those having a critical ratio of clauses to variables - the spectral fluctuations typically become irregular across a contiguous region of the interpolation parameter, while the spectrum is regular for easy instances. Within the hard region, RMT may be applied to obtain a mathematical model of the probability of avoided level crossings and concomitant failure rate of the adiabatic algorithm due to nonadiabatic Landau-Zener-type transitions. Our model predicts that if the interpolation is performed at a uniform rate, the average failure rate of the quantum adiabatic algorithm, when averaged over hard problem instances, scales exponentially with increasing problem size.
Four-modulus ``Swiss Cheese'' chiral models
NASA Astrophysics Data System (ADS)
Collinucci, Andrés; Kreuzer, Maximilian; Mayrhofer, Christoph; Walliser, Nils-Ole
2009-07-01
We study the `Large Volume Scenario' on explicit, new, compact, four-modulus Calabi-Yau manifolds. We pay special attention to the chirality problem pointed out by Blumenhagen, Moster and Plauschinn. Namely, we thoroughly analyze the possibility of generating neutral, non-perturbative superpotentials from Euclidean D3-branes in the presence of chirally intersecting D7-branes. We find that taking proper account of the Freed-Witten anomaly on non-spin cycles and of the Kähler cone conditions imposes severe constraints on the models. Nevertheless, we are able to create setups where the constraints are solved, and up to three moduli are stabilized.
Active Tensile Modulus of an Epithelial Monolayer
NASA Astrophysics Data System (ADS)
Vincent, Romaric; Bazellières, Elsa; Pérez-González, Carlos; Uroz, Marina; Serra-Picamal, Xavier; Trepat, Xavier
2015-12-01
A general trait of cell monolayers is their ability to exert contractile stresses on their surroundings. The scaling laws that link such contractile stresses with the size and geometry of constituent cells remain largely unknown. In this Letter, we show that the active tension of an epithelial monolayer scales linearly with the size of the constituent cells, a surprisingly simple relationship. The slope of this relationship defines an active tensile modulus, which depends on the concentration of myosin and spans more than 2 orders of magnitude across cell types and molecular perturbations.
Non-adiabatic effects in near-adiabatic mixed-field orientation and alignment
NASA Astrophysics Data System (ADS)
Maan, Anjali; Ahlawat, Dharamvir Singh; Prasad, Vinod
2016-11-01
We present a theoretical study of the impact of a pair of moderate electric fields tilted an angle with respect to one another on a molecule. As a prototype, we consider a molecule with large rotational constant (with corresponding small rotational period) and moderate dipole moment. Within rigid-rotor approximation, the time-dependent Schrodinger equation is solved using fourth-order Runge-Kutta method. We have analysed that lower rotational states are significantly influenced by variation in pulse durations, the tilt angle between the fields and also on the electric field strengths. We also suggest a control scheme of how the rotational dynamics, orientation and alignment of a molecule can be enhanced by a combination of near-adiabatic pulses in comparision to non-adiabatic or adiabatic pulses.
Development of a new β Ti alloy with low modulus and favorable plasticity for implant material.
Liang, S X; Feng, X J; Yin, L X; Liu, X Y; Ma, M Z; Liu, R P
2016-04-01
One of the most important development directions of the Ti and its alloys is the applications in medical field. Development of new Ti alloys with low elastic modulus and/or favorable biocompatibility plays an important role for promoting its application in medical field. In this work, a new β Ti alloy (Ti-31Nb-6Zr-5Mo, wt.%) was designed for implant material using d-electron alloy design method. Microstructure and tensile properties of the designed alloy after hot rolling (HR) and solution followed by aging treatments (SA) were investigated. Results show that the designed alloy is composed of single β phase. However, microstructural analysis shows that the β phase in the designed alloy separates into Nb-rich and Nb-poor phase regions. The Nb-rich regions in HR specimen are typical elongated fiber texture, but are equiaxed particles with several micrometers in SA specimen. Tensile results show that the designed alloy has low Young's modulus of 44 GPa for HR specimen and 48 GPa for SA specimen which are very close to the extreme of Young's modulus of bulk titanium alloys. At the same time, the designed alloy has favorable plasticity in term of elongation of 26.7% for HR specimen and 20.6% for SA specimen, and appropriate tensile strength over 700 MPa. In short, the designed alloy has low elastic modulus close to that of bone and favorable plasticity and strength which can be a potential candidate for hard tissue replacements. PMID:26838858
The thermal conductivity of high modulus Zylon fibers between 400 mK and 4 K
NASA Astrophysics Data System (ADS)
Wikus, Patrick; Figueroa-Feliciano, Enectalí; Hertel, Scott A.; Leman, Steven W.; McCarthy, Kevin A.; Rutherford, John M.
2008-11-01
Zylon is a synthetic polyurethane polymer fiber featuring very high mechanical strength. Measurements of the thermal conductivity λZ(T) of high modulus Zylon fibers at temperatures between 400 mK and 4 K were performed to assess if they can be successfully employed in the design of high performance suspension systems for cold stages of adiabatic demagnetization refrigerators. The linear mass density of the yarn used in these measurements amounts to 3270 dtex, which is also a measure for the yarn's cross section. The experimental data for the thermal conductivity was fitted to a function of the form λZ=(1010±30)·TpWmmdtexK. This result was normalized to the breaking strength of the fibers and compared with Kevlar. It shows that Kevlar outperforms Zylon in the investigated temperature range. At 1.5 K, the thermal conductivity integral of Zylon yarn is twice as high as the thermal conductivity integral of Kevlar yarn with the same breaking strength. A linear mass density of 1 tex is equivalent to a yarn mass of 1 g/km. High modulus Zylon has a density of 1.56 g/cm 3.
Bond selective chemistry beyond the adiabatic approximation
Butler, L.J.
1993-12-01
One of the most important challenges in chemistry is to develop predictive ability for the branching between energetically allowed chemical reaction pathways. Such predictive capability, coupled with a fundamental understanding of the important molecular interactions, is essential to the development and utilization of new fuels and the design of efficient combustion processes. Existing transition state and exact quantum theories successfully predict the branching between available product channels for systems in which each reaction coordinate can be adequately described by different paths along a single adiabatic potential energy surface. In particular, unimolecular dissociation following thermal, infrared multiphoton, or overtone excitation in the ground state yields a branching between energetically allowed product channels which can be successfully predicted by the application of statistical theories, i.e. the weakest bond breaks. (The predictions are particularly good for competing reactions in which when there is no saddle point along the reaction coordinates, as in simple bond fission reactions.) The predicted lack of bond selectivity results from the assumption of rapid internal vibrational energy redistribution and the implicit use of a single adiabatic Born-Oppenheimer potential energy surface for the reaction. However, the adiabatic approximation is not valid for the reaction of a wide variety of energetic materials and organic fuels; coupling between the electronic states of the reacting species play a a key role in determining the selectivity of the chemical reactions induced. The work described below investigated the central role played by coupling between electronic states in polyatomic molecules in determining the selective branching between energetically allowed fragmentation pathways in two key systems.
Spontaneous freezing of supercooled water under isochoric and adiabatic conditions.
Prestipino, Santi; Giaquinta, Paolo V
2013-07-11
The return of a supercooled liquid to equilibrium usually begins with a fast heating up of the sample which ends when the system reaches the equilibrium freezing temperature. At this stage, the system is still a microsegregated mixture of solid and liquid. Only later is solidification completed through the exchange of energy with the surroundings. Using the IAPWS-95 formulation, we investigate the adiabatic freezing of supercooled water in a closed and rigid vessel, i.e., under thermally and mechanically isolated conditions, which captures the initial stage of the decay of metastable water to equilibrium. To improve realism further, we also account for a fixed amount of foreign gas in the vessel. Under the simplifying assumption that the system is at equilibrium immediately after the nominal freezing temperature has been attained, we determine-as a function of undercooling and gas mole number-the final temperature and pressure of the system, the fraction of ice at equilibrium, and the entropy increase. Assuming a nonzero energy cost for the ice-water interface, we also show that, unless sufficiently undercooled, perfectly isolated pure-water droplets cannot start freezing in the bulk.
Shortcut to adiabaticity in spinor condensates
NASA Astrophysics Data System (ADS)
Sala, Arnau; Núñez, David López; Martorell, Joan; De Sarlo, Luigi; Zibold, Tilman; Gerbier, Fabrice; Polls, Artur; Juliá-Díaz, Bruno
2016-10-01
We devise a method to shortcut the adiabatic evolution of a spin-1 Bose gas with an external magnetic field as the control parameter. An initial many-body state with almost all bosons populating the Zeeman sublevel m =0 is evolved to a final state very close to a macroscopic spin-singlet condensate, a fragmented state with three macroscopically occupied Zeeman states. The shortcut protocol, obtained by an approximate mapping to a harmonic oscillator Hamiltonian, is compared to linear and exponential variations of the control parameter. We find a dramatic speedup of the dynamics when using the shortcut protocol.
On adiabatic perturbations in the ekpyrotic scenario
Linde, A.; Mukhanov, V.; Vikman, A. E-mail: Viatcheslav.Mukhanov@physik.uni-muenchen.de
2010-02-01
In a recent paper, Khoury and Steinhardt proposed a way to generate adiabatic cosmological perturbations with a nearly flat spectrum in a contracting Universe. To produce these perturbations they used a regime in which the equation of state exponentially rapidly changed during a short time interval. Leaving aside the singularity problem and the difficult question about the possibility to transmit these perturbations from a contracting Universe to the expanding phase, we will show that the methods used in Khoury are inapplicable for the description of the cosmological evolution and of the process of generation of perturbations in this scenario.
Generalized Ramsey numbers through adiabatic quantum optimization
NASA Astrophysics Data System (ADS)
Ranjbar, Mani; Macready, William G.; Clark, Lane; Gaitan, Frank
2016-09-01
Ramsey theory is an active research area in combinatorics whose central theme is the emergence of order in large disordered structures, with Ramsey numbers marking the threshold at which this order first appears. For generalized Ramsey numbers r( G, H), the emergent order is characterized by graphs G and H. In this paper we: (i) present a quantum algorithm for computing generalized Ramsey numbers by reformulating the computation as a combinatorial optimization problem which is solved using adiabatic quantum optimization; and (ii) determine the Ramsey numbers r({{T}}m,{{T}}n) for trees of order m,n = 6,7,8, most of which were previously unknown.
Cavity-state preparation using adiabatic transfer
NASA Astrophysics Data System (ADS)
Larson, Jonas; Andersson, Erika
2005-05-01
We show how to prepare a variety of cavity field states for multiple cavities. The state preparation technique used is related to the method of stimulated adiabatic Raman passage. The cavity modes are coupled by atoms, making it possible to transfer an arbitrary cavity field state from one cavity to another and also to prepare nontrivial cavity field states. In particular, we show how to prepare entangled states of two or more cavities, such as an Einstein-Podolsky-Rosen state and a W state, as well as various entangled superpositions of coherent states in different cavities, including Schrödinger cat states. The theoretical considerations are supported by numerical simulations.
Phase avalanches in near-adiabatic evolutions
Vertesi, T.; Englman, R.
2006-02-15
In the course of slow, nearly adiabatic motion of a system, relative changes in the slowness can cause abrupt and high magnitude phase changes, ''phase avalanches,'' superimposed on the ordinary geometric phases. The generality of this effect is examined for arbitrary Hamiltonians and multicomponent (>2) wave packets and is found to be connected (through the Blaschke term in the theory of analytic signals) to amplitude zeros in the lower half of the complex time plane. Motion on a nonmaximal circle on the Poincare-sphere suppresses the effect. A spectroscopic transition experiment can independently verify the phase-avalanche magnitudes.
Local entanglement generation in the adiabatic regime
Cliche, M.; Veitia, Andrzej
2010-09-15
We study entanglement generation in a pair of qubits interacting with an initially correlated system. Using time-independent perturbation theory and the adiabatic theorem, we show conditions under which the qubits become entangled as the joint system evolves into the ground state of the interacting theory. We then apply these results to the case of qubits interacting with a scalar quantum field. We study three different variations of this setup; a quantum field subject to Dirichlet boundary conditions, a quantum field interacting with a classical potential, and a quantum field that starts in a thermal state.
An adiabatic demagnetization refrigerator for infrared bolometers
NASA Technical Reports Server (NTRS)
Britt, R. D.; Richards, P. L.
1981-01-01
Adiabatic demagnetization refrigerators have been built and installed in small portable liquid helium cryostats to test the feasibility of this method of cooling infrared bolometric detectors to temperatures below 0.3 K. Performance has been achieved which suggests that bolometer temperatures of 0.2 K can be maintained for periods of approximately 60 hours. Applications to sensitive infrared detection from ground-based telescopes and space satellites are discussed. Design data are given which permit the evaluation of refrigerator performance for a variety of design parameters.
Shear modulus of structured electrorheological fluid mixtures.
Shitara, Kyohei; Sakaue, Takahiro
2016-05-01
Some immiscible blends under a strong electric field often exhibit periodic structures, bridging the gap between two electrodes. Upon shear, the structures tilt, and exhibit an elastic response which is mostly governed by the electric energy. Assuming a two-dimensional stripe structure, we calculate the Maxwell stress, and derive an expression for the shear modulus, demonstrating how it depends on the external electric field, the composition, and the dielectric properties of the blend. We also suggest the notion of effective interfacial tension, which renormalizes the effect of the electric field. This leads to a simple derivation of the scaling law for the selection of the wavelength of the structure formed under an electric field. PMID:27300947
Shear modulus of structured electrorheological fluid mixtures
NASA Astrophysics Data System (ADS)
Shitara, Kyohei; Sakaue, Takahiro
2016-05-01
Some immiscible blends under a strong electric field often exhibit periodic structures, bridging the gap between two electrodes. Upon shear, the structures tilt, and exhibit an elastic response which is mostly governed by the electric energy. Assuming a two-dimensional stripe structure, we calculate the Maxwell stress, and derive an expression for the shear modulus, demonstrating how it depends on the external electric field, the composition, and the dielectric properties of the blend. We also suggest the notion of effective interfacial tension, which renormalizes the effect of the electric field. This leads to a simple derivation of the scaling law for the selection of the wavelength of the structure formed under an electric field.
NASA Astrophysics Data System (ADS)
Wilson, Leslie Hoipkemeier
Biofouling is the accumulation of biological matter on a substrate. It is essential to elucidate and model the major factors that affect both biological settlement and adhesion to substrates in order to develop coatings that minimize initial fouling or ease the removal of this fouling. To date, models that have estimated adhesion strength to coatings primarily included bulk elastic modulus and surface energy. Topography, however, has been found to dominate both these terms in the reduction of settlement and has been found to affect the adhesion strength as well. Silicone foul release coatings have demonstrated moderate success in the prevention of marine biofouling because of their low modulus and low surface energy. Problems exist with durability and eventual fouling of the coating due to the overgrowth of foulants that prefer hydrophobic substrates. This research details the characterization and the surface and bulk modification of a commercially available silicone elastomer. The modifications include bulk additives, surface topography, and surface graft copolymers. The effect of these modifications on biological response was then assayed using the alga Ulva as a model for marine biofouling. The unmodified silicone elastomer has a bulk modulus of approximately 1 MPa. The addition of vinyl functional polydimethylsiloxane oils allowed for a greater than 200% increase or a 90% decrease in the bulk modulus of the material. The addition of non-reactive polydimethylsiloxane oils allowed for a change in the surface lubricity of the elastomer without a significant change in the mechanical properties. Topographical modifications of the surface show a profound effect on the bioresponse. Appropriately scaled engineered microtopographies replicated in the silicone elastomer can produce a 250% increase in algal zoospore fouling or an 85% reduction in settlement relative to a smooth silicone elastomer. Finally, the modification of the surface energy of this material was
Adiabatic cooling of solar wind electrons
NASA Technical Reports Server (NTRS)
Sandbaek, Ornulf; Leer, Egil
1992-01-01
In thermally driven winds emanating from regions in the solar corona with base electron densities of n0 not less than 10 exp 8/cu cm, a substantial fraction of the heat conductive flux from the base is transfered into flow energy by the pressure gradient force. The adiabatic cooling of the electrons causes the electron temperature profile to fall off more rapidly than in heat conduction dominated flows. Alfven waves of solar origin, accelerating the basically thermally driven solar wind, lead to an increased mass flux and enhanced adiabatic cooling. The reduction in electron temperature may be significant also in the subsonic region of the flow and lead to a moderate increase of solar wind mass flux with increasing Alfven wave amplitude. In the solar wind model presented here the Alfven wave energy flux per unit mass is larger than that in models where the temperature in the subsonic flow is not reduced by the wave, and consequently the asymptotic flow speed is higher.
Quantum Adiabatic Algorithms and Large Spin Tunnelling
NASA Technical Reports Server (NTRS)
Boulatov, A.; Smelyanskiy, V. N.
2003-01-01
We provide a theoretical study of the quantum adiabatic evolution algorithm with different evolution paths proposed in this paper. The algorithm is applied to a random binary optimization problem (a version of the 3-Satisfiability problem) where the n-bit cost function is symmetric with respect to the permutation of individual bits. The evolution paths are produced, using the generic control Hamiltonians H (r) that preserve the bit symmetry of the underlying optimization problem. In the case where the ground state of H(0) coincides with the totally-symmetric state of an n-qubit system the algorithm dynamics is completely described in terms of the motion of a spin-n/2. We show that different control Hamiltonians can be parameterized by a set of independent parameters that are expansion coefficients of H (r) in a certain universal set of operators. Only one of these operators can be responsible for avoiding the tunnelling in the spin-n/2 system during the quantum adiabatic algorithm. We show that it is possible to select a coefficient for this operator that guarantees a polynomial complexity of the algorithm for all problem instances. We show that a successful evolution path of the algorithm always corresponds to the trajectory of a classical spin-n/2 and provide a complete characterization of such paths.
Effect of the Heat Pipe Adiabatic Region.
Brahim, Taoufik; Jemni, Abdelmajid
2014-04-01
The main motivation of conducting this work is to present a rigorous analysis and investigation of the potential effect of the heat pipe adiabatic region on the flow and heat transfer performance of a heat pipe under varying evaporator and condenser conditions. A two-dimensional steady-state model for a cylindrical heat pipe coupling, for both regions, is presented, where the flow of the fluid in the porous structure is described by Darcy-Brinkman-Forchheimer model which accounts for the boundary and inertial effects. The model is solved numerically by using the finite volumes method, and a fortran code was developed to solve the system of equations obtained. The results show that a phase change can occur in the adiabatic region due to temperature gradient created in the porous structure as the heat input increases and the heat pipe boundary conditions change. A recirculation zone may be created at the condenser end section. The effect of the heat transfer rate on the vapor radial velocities and the performance of the heat pipe are discussed. PMID:24895467
Effective elastic modulus of isolated gecko setal arrays.
Autumn, K; Majidi, C; Groff, R E; Dittmore, A; Fearing, R
2006-09-01
Conventional pressure sensitive adhesives (PSAs) are fabricated from soft viscoelastic materials that satisfy Dahlquist's criterion for tack with a Young's modulus (E) of 100 kPa or less at room temperature and 1 Hz. In contrast, the adhesive on the toes of geckos is made of beta-keratin, a stiff material with E at least four orders of magnitude greater than the upper limit of Dahlquist's criterion. Therefore, one would not expect a beta-keratin structure to function as a PSA by deforming readily to make intimate molecular contact with a variety of surface profiles. However, since the gecko adhesive is a microstructure in the form of an array of millions of high aspect ratio shafts (setae), the effective elastic modulus (E(eff)) is much lower than E of bulk beta-keratin. In the first test of the E(eff) of a gecko setal adhesive, we measured the forces resulting from deformation of isolated arrays of tokay gecko (Gekko gecko) setae during vertical compression, and during tangential compression at angles of +45 degrees and -45 degrees . We tested the hypothesis that E(eff) of gecko setae falls within Dahlquist's criterion for tack, and evaluated the validity of a model of setae as cantilever beams. Highly linear forces of deformation under all compression conditions support the cantilever model. E(eff) of setal arrays during vertical and +45 degrees compression (along the natural path of drag of the setae) were 83+/-4.0 kPa and 86+/-4.4 kPa (means +/- s.e.m.), respectively. Consistent with the predictions of the cantilever model, setae became significantly stiffer when compressed against the natural path of drag: E(eff) during -45 degrees compression was 110+/-4.7 kPa. Unlike synthetic PSAs, setal arrays act as Hookean elastic solids; setal arrays function as a bed of springs with a directional stiffness, assisting alignment of the adhesive spatular tips with the contact surface during shear loading.
Generation of Pure Bulk Valley Current in Graphene
NASA Astrophysics Data System (ADS)
Jiang, Yongjin; Low, Tony; Chang, Kai; Katsnelson, Mikhail I.; Guinea, Francisco
2013-01-01
The generation of valley current is a fundamental goal in graphene valleytronics but no practical ways of its realization are known yet. We propose a workable scheme for the generation of bulk valley current in a graphene mechanical resonator through adiabatic cyclic deformations of the strains and a chemical potential in the suspended region. The accompanied strain gauge fields can break the spatial mirror symmetry of the problem within each of the two inequivalent valleys, leading to a finite valley current due to quantum pumping. An all-electrical measurement configuration is designed to detect the novel state with pure bulk valley currents.
Adiabat Shaping of ICF Capsules Using Ramped Pressure Profiles
NASA Astrophysics Data System (ADS)
Anderson, K.; Betti, R.; Collins, T. J. B.; Marinak, M. M.; Haan, S. W.
2002-11-01
Target design of direct-drive ICF capsules has historically involved a compromise between high 1-D (clean) yield and capsule stability. Low-adiabat fuel is desirable to achieve high compression and, hence, high yield. A higher adiabat at the ablation front reduces the growth rate of the Raleigh--Taylor instability due to higher ablation velocity. An optimal target design will take advantage of both by shaping the adiabat of the capsule to allow for high adiabat in the material that is to be ablated and low adiabat in the remaining fuel. We present here a method of adiabat shaping using a low-intensity prepulse followed by laser shutoff before beginning the main drive pulse. This creates a decaying shock with a ramped pressure profile behind it. Since the prepulse is low intensity, the adiabat is not strongly affected by the prepulse. The main shock is then launched up this ramped pressure profile to set the adiabat. Because the main shock sees an increasing pressure profile, the effective strength of the shock decreases as it propagates through the shell, thus creating a smooth adiabat profile from high outer-shell adiabat to low inner-shell adiabat. Results of simulations using 1-D LILAC and 2-D DRACO (LLE), as well as 1-D and 2-D HYDRA (LLNL), are presented. This work was supported by the U.S. DOE Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460 and by the University of California LLNL under contract No. W-7405-Eng-48.
Thulium-based bulk metallic glass
Yu, H. B.; Yu, P.; Wang, W. H.; Bai, H. Y.
2008-04-07
We report the formation and properties of a thulium-based bulk metallic glass (BMG). Compared with other known rare-earth (RE) based BMGs, Tm-based BMGs show features of excellent glass formation ability, considerable higher elastic modulus, smaller Poisson's ratio, high mechanical strength, and intrinsic brittleness. The reasons for the different properties between the Tm-based and other RE-based BMGs are discussed. It is expected that the Tm-based glasses with the unique properties are appropriate candidates for studying some important issues in BMGs.
The Adiabatic Invariance of the Action Variable in Classical Dynamics
ERIC Educational Resources Information Center
Wells, Clive G.; Siklos, Stephen T. C.
2007-01-01
We consider one-dimensional classical time-dependent Hamiltonian systems with quasi-periodic orbits. It is well known that such systems possess an adiabatic invariant which coincides with the action variable of the Hamiltonian formalism. We present a new proof of the adiabatic invariance of this quantity and illustrate our arguments by means of…
Generation of atomic NOON states via shortcuts to adiabatic passage
NASA Astrophysics Data System (ADS)
Song, Chong; Su, Shi-Lei; Bai, Cheng-Hua; Ji, Xin; Zhang, Shou
2016-10-01
Based on Lewis-Riesenfeld invariants and quantum Zeno dynamics, we propose an effective scheme for generating atomic NOON states via shortcuts to adiabatic passage. The photon losses are efficiently suppressed by engineering shortcuts to adiabatic passage in the scheme. The numerical simulation shows that the atomic NOON states can be generated with high fidelity.
Kinetic Theory Derivation of the Adiabatic Law for Ideal Gases.
ERIC Educational Resources Information Center
Sobel, Michael I.
1980-01-01
Discusses how the adiabatic law for ideal gases can be derived from the assumption of a Maxwell-Boltzmann (or any other) distribution of velocities--in contrast to the usual derivations from thermodynamics alone, and the higher-order effect that leads to one-body viscosity. An elementary derivation of the adiabatic law is given. (Author/DS)
Adiabat-shaping in indirect drive inertial confinement fusion
Baker, K. L.; Robey, H. F.; Milovich, J. L.; Jones, O. S.; Smalyuk, V. A.; Casey, D. T.; MacPhee, A. G.; Pak, A.; Celliers, P. M.; Clark, D. S.; Landen, O. L.; Peterson, J. L.; Berzak-Hopkins, L. F.; Weber, C. R.; Haan, S. W.; Döppner, T. D.; Dixit, S.; Hamza, A. V.; Jancaitis, K. S.; Kroll, J. J.; and others
2015-05-15
Adiabat-shaping techniques were investigated in indirect drive inertial confinement fusion experiments on the National Ignition Facility as a means to improve implosion stability, while still maintaining a low adiabat in the fuel. Adiabat-shaping was accomplished in these indirect drive experiments by altering the ratio of the picket and trough energies in the laser pulse shape, thus driving a decaying first shock in the ablator. This decaying first shock is designed to place the ablation front on a high adiabat while keeping the fuel on a low adiabat. These experiments were conducted using the keyhole experimental platform for both three and four shock laser pulses. This platform enabled direct measurement of the shock velocities driven in the glow-discharge polymer capsule and in the liquid deuterium, the surrogate fuel for a DT ignition target. The measured shock velocities and radiation drive histories are compared to previous three and four shock laser pulses. This comparison indicates that in the case of adiabat shaping the ablation front initially drives a high shock velocity, and therefore, a high shock pressure and adiabat. The shock then decays as it travels through the ablator to pressures similar to the original low-adiabat pulses when it reaches the fuel. This approach takes advantage of initial high ablation velocity, which favors stability, and high-compression, which favors high stagnation pressures.
An adiabatic demagnetization refrigerator for SIRTF
NASA Technical Reports Server (NTRS)
Timbie, P. T.; Bernstein, G. M.; Richards, P. L.
1989-01-01
An adiabatic demagnetization refrigerator (ADR) has been proposed to cool bolometric infrared detectors on the multiband imaging photometer of the Space Infrared Telescope Facility (SIRTF). One such refrigerator has been built which uses a ferric ammonium alum salt pill suspended by nylon threads in a 3-T solenoid. The resonant modes of this suspension are above 100 Hz. The heat leak to the salt pill is less than 0.5 microW. The system has a hold time at 0.1K of more than 12 h. The cold stage temperature is regulated with a feedback loop that controls the magnetic field. A second, similar refrigerator is being built at a SIRTF prototype to fly on a ballon-borne telescope. It will use a ferromagnetic shield. The possibility of using a high-Tc solenoid-actuated heat switch is also discussed.
An adiabatic demagnetization refrigerator for SIRTF
Timbie, P.T.; Bernstein, G.M.; Richards, P.L.
1989-02-01
An adiabatic demagnetization refrigerator (ADR) has been proposed to cool bolometric infrared detectors on the Multiband Imaging Photometer of the Space Infrared Telescope Facility (SIRTF). The authors have built one such refrigerator which employs a ferric ammonium alum salt pill suspended by nylon threads in a 3 Tesla solenoid. The resonant modes of this suspension are above 100 Hz. The heat leak to the salt pill is <0.5 ..mu..W. The system has a hold time at 0.1 /sup 0/K of >12 hours. The cold stage temperature is regulated with a feedback loop that controls the magnetic field. A second, similar refrigerator is being built as a SIRTF prototype to fly on a balloon-borne telescope. It will employ a ferromagnetic shield. The possibility of using high T/sub c/ leads to the superconducting magnet and a solenoid-actuated heat switch are also discussed.
The HAWC and SAFIRE Adiabatic Demagnetization Refrigerators
NASA Technical Reports Server (NTRS)
Tuttle, Jim; Shirron, Peter; DiPirro, Michael; Jackson, Michael; Behr, Jason; Kunes, Evan; Hait, Tom; Krebs, Carolyn (Technical Monitor)
2001-01-01
The High-Resolution Airborne Wide-band Camera (HAWC) and Submillimeter and Far Infrared Experiment (SAFIRE) are far-infrared experiments which will fly on the Stratospheric Observatory for Infrared Astronomy (SOFIA) aircraft. HAWC's detectors will operate at 0.2 Kelvin, while those of SAFIRE will be at 0.1 Kelvin. Each instrument will include an adiabatic demagnetization refrigerator (ADR) to cool its detector stage from the liquid helium bath temperature (HAWC's at 4.2 Kelvin and SAFIRE's pumped to about 1.3 Kelvin) to its operating temperature. Except for the magnets used to achieve the cooling and a slight difference in the heat switch design, the two ADRs are nearly identical. We describe the ADR design and present the results of performance testing.
Number Partitioning via Quantum Adiabatic Computation
NASA Technical Reports Server (NTRS)
Smelyanskiy, Vadim N.; Toussaint, Udo; Clancy, Daniel (Technical Monitor)
2002-01-01
We study both analytically and numerically the complexity of the adiabatic quantum evolution algorithm applied to random instances of combinatorial optimization problems. We use as an example the NP-complete set partition problem and obtain an asymptotic expression for the minimal gap separating the ground and exited states of a system during the execution of the algorithm. We show that for computationally hard problem instances the size of the minimal gap scales exponentially with the problem size. This result is in qualitative agreement with the direct numerical simulation of the algorithm for small instances of the set partition problem. We describe the statistical properties of the optimization problem that are responsible for the exponential behavior of the algorithm.
Differential topology of adiabatically controlled quantum processes
NASA Astrophysics Data System (ADS)
Jonckheere, Edmond A.; Rezakhani, Ali T.; Ahmad, Farooq
2013-03-01
It is shown that in a controlled adiabatic homotopy between two Hamiltonians, H 0 and H 1, the gap or "anti-crossing" phenomenon can be viewed as the development of cusps and swallow tails in the region of the complex plane where two critical value curves of the quadratic map associated with the numerical range of H 0 + i H 1 come close. The "near crossing" in the energy level plots happens to be a generic situation, in the sense that a crossing is a manifestation of the quadratic numerical range map being unstable in the sense of differential topology. The stable singularities that can develop are identified and it is shown that they could occur near the gap, making those singularities of paramount importance. Various applications, including the quantum random walk, are provided to illustrate this theory.
Quantum Adiabatic Optimization and Combinatorial Landscapes
NASA Technical Reports Server (NTRS)
Smelyanskiy, V. N.; Knysh, S.; Morris, R. D.
2003-01-01
In this paper we analyze the performance of the Quantum Adiabatic Evolution (QAE) algorithm on a variant of Satisfiability problem for an ensemble of random graphs parametrized by the ratio of clauses to variables, gamma = M / N. We introduce a set of macroscopic parameters (landscapes) and put forward an ansatz of universality for random bit flips. We then formulate the problem of finding the smallest eigenvalue and the excitation gap as a statistical mechanics problem. We use the so-called annealing approximation with a refinement that a finite set of macroscopic variables (verses only energy) is used, and are able to show the existence of a dynamic threshold gamma = gammad, beyond which QAE should take an exponentially long time to find a solution. We compare the results for extended and simplified sets of landscapes and provide numerical evidence in support of our universality ansatz.
Geometric Adiabatic Transport in Quantum Hall States.
Klevtsov, S; Wiegmann, P
2015-08-21
We argue that in addition to the Hall conductance and the nondissipative component of the viscous tensor, there exists a third independent transport coefficient, which is precisely quantized. It takes constant values along quantum Hall plateaus. We show that the new coefficient is the Chern number of a vector bundle over moduli space of surfaces of genus 2 or higher and therefore cannot change continuously along the plateau. As such, it does not transpire on a sphere or a torus. In the linear response theory, this coefficient determines intensive forces exerted on electronic fluid by adiabatic deformations of geometry and represents the effect of the gravitational anomaly. We also present the method of computing the transport coefficients for quantum Hall states. PMID:26340197
Geometric Adiabatic Transport in Quantum Hall States.
Klevtsov, S; Wiegmann, P
2015-08-21
We argue that in addition to the Hall conductance and the nondissipative component of the viscous tensor, there exists a third independent transport coefficient, which is precisely quantized. It takes constant values along quantum Hall plateaus. We show that the new coefficient is the Chern number of a vector bundle over moduli space of surfaces of genus 2 or higher and therefore cannot change continuously along the plateau. As such, it does not transpire on a sphere or a torus. In the linear response theory, this coefficient determines intensive forces exerted on electronic fluid by adiabatic deformations of geometry and represents the effect of the gravitational anomaly. We also present the method of computing the transport coefficients for quantum Hall states.
Adiabatic frequency conversion of ultrafast pulses
NASA Astrophysics Data System (ADS)
Suchowski, H.; Bruner, B. D.; Ganany-Padowicz, A.; Juwiler, I.; Arie, A.; Silberberg, Y.
2011-12-01
A new method for efficient, broadband sum and difference frequency generation of ultrafast pulses is demonstrated. The principles of the method follow from an analogy between frequency conversion and coherent optical excitation of a two-level system. For conversion of ultrafast pulses, the concepts of adiabatic conversion are developed further in order to account for dispersion and group velocity mismatch. The scheme was implemented using aperiodically poled nonlinear crystals and a single step nonlinear mixing process, leading to conversion of near-IR (˜790 nm) ultrafast pulses into the blue (˜450 nm) and mid-IR (˜3.15 μm) spectral regions. Conversion bandwidths up to 15 THz FWHM and efficiencies up to 50% are reported.
Stirling engine with one adiabatic cylinder
NASA Astrophysics Data System (ADS)
West, C. D.
1982-03-01
It is shown that integration around the P-V loop of a Stirling-like cycle with an adiabatic expansion or compression space is possible through careful application of the ideal gas laws. The result is a set of closed-form solutions or the work output, work input, and efficiency for ideal gases. Previous analyses yielded closed-form solutions only for machines in which all spaces behave isothermally, or that have other limitations that simplify the arithmetic but omit important aspects of real machines. The results of this analysis, although still far removed from the exact behavior of real, practical engines, yield important insights into the effects observed in computer models and experimental machines. These results are especially illuminating for machines intended to operate with fairly small temperature differences. Heat pumps and low-technology solar-powered engines might be included in this category.
Adiabatic connection at negative coupling strengths
Seidl, Michael; Gori-Giorgi, Paola
2010-01-15
The adiabatic connection of density functional theory (DFT) for electronic systems is generalized here to negative values of the coupling strength alpha (with attractive electrons). In the extreme limit alpha->-infinity a simple physical solution is presented and its implications for DFT (as well as its limitations) are discussed. For two-electron systems (a case in which the present solution can be calculated exactly), we find that an interpolation between the limit alpha->-infinity and the opposite limit of infinitely strong repulsion (alpha->+infinity) yields a rather accurate estimate of the second-order correlation energy E{sub c}{sup GL2}[rho] for several different densities rho, without using virtual orbitals. The same procedure is also applied to the Be isoelectronic series, analyzing the effects of near degeneracy.
Sliding seal materials for adiabatic engines
NASA Technical Reports Server (NTRS)
Lankford, J.
1985-01-01
The sliding friction coefficients and wear rates of promising carbide, oxide, and nitride materials were measured under temperature, environmental, velocity, loading conditions that are representative of the adiabatic engine environment. In order to provide guidance needed to improve materials for this application, the program stressed fundamental understanding of the mechanisms involved in friction and wear. Microhardness tests were performed on the candidate materials at elevated temperatures, and in atmospheres relevant to the piston seal application, and optical and electron microscopy were used to elucidate the micromechanisms of wear following wear testing. X-ray spectroscopy was used to evaluate interface/environment interactions which seemed to be important in the friction and wear process. Electrical effects in the friction and wear processes were explored in order to evaluate the potential usefulness of such effects in modifying the friction and wear rates in service. However, this factor was found to be of negligible significance in controlling friction and wear.
Adiabatic theory for anisotropic cold molecule collisions
Pawlak, Mariusz; Shagam, Yuval; Narevicius, Edvardas; Moiseyev, Nimrod
2015-08-21
We developed an adiabatic theory for cold anisotropic collisions between slow atoms and cold molecules. It enables us to investigate the importance of the couplings between the projection states of the rotational motion of the atom about the molecular axis of the diatom. We tested our theory using the recent results from the Penning ionization reaction experiment {sup 4}He(1s2s {sup 3}S) + HD(1s{sup 2}) → {sup 4}He(1s{sup 2}) + HD{sup +}(1s) + e{sup −} [Lavert-Ofir et al., Nat. Chem. 6, 332 (2014)] and demonstrated that the couplings have strong effect on positions of shape resonances. The theory we derived provides cross sections which are in a very good agreement with the experimental findings.
Lattice Boltzmann method for adiabatic acoustics.
Li, Yanbing; Shan, Xiaowen
2011-06-13
The lattice Boltzmann method (LBM) has been proved to be a useful tool in many areas of computational fluid dynamics, including computational aero-acoustics (CAA). However, for historical reasons, its applications in CAA have been largely restricted to simulations of isothermal (Newtonian) sound waves. As the recent kinetic theory-based reformulation establishes a theoretical framework in which LBM can be extended to recover the full Navier-Stokes-Fourier (NS) equations and beyond, in this paper, we show that, at least at the low-frequency limit (sound frequency much less than molecular collision frequency), adiabatic sound waves can be accurately simulated by the LBM provided that the lattice and the distribution function ensure adequate recovery of the full NS equations.
Maronde, Carl P.; Killmeyer JR., Richard P.
1992-03-03
An apparatus for the disbursement of a bulk solid sample comprising, a gravity hopper having a top open end and a bottom discharge end, a feeder positioned beneath the gravity hopper so as to receive a bulk solid sample flowing from the bottom discharge end, and a conveyor receiving the bulk solid sample from the feeder and rotating on an axis that allows the bulk solid sample to disperse the sample to a collection station.
Maronde, Carl P.; Killmeyer, Jr., Richard P.
1992-01-01
An apparatus for the disbursement of a bulk solid sample comprising, a gravity hopper having a top open end and a bottom discharge end, a feeder positioned beneath the gravity hopper so as to receive a bulk solid sample flowing from the bottom discharge end, and a conveyor receiving the bulk solid sample from the feeder and rotating on an axis that allows the bulk solid sample to disperse the sample to a collection station.
An integrated programming and development environment for adiabatic quantum optimization
NASA Astrophysics Data System (ADS)
Humble, T. S.; McCaskey, A. J.; Bennink, R. S.; Billings, J. J.; DʼAzevedo, E. F.; Sullivan, B. D.; Klymko, C. F.; Seddiqi, H.
2014-01-01
Adiabatic quantum computing is a promising route to the computational power afforded by quantum information processing. The recent availability of adiabatic hardware has raised challenging questions about how to evaluate adiabatic quantum optimization (AQO) programs. Processor behavior depends on multiple steps to synthesize an adiabatic quantum program, which are each highly tunable. We present an integrated programming and development environment for AQO called Jade Adiabatic Development Environment (JADE) that provides control over all the steps taken during program synthesis. JADE captures the workflow needed to rigorously specify the AQO algorithm while allowing a variety of problem types, programming techniques, and processor configurations. We have also integrated JADE with a quantum simulation engine that enables program profiling using numerical calculation. The computational engine supports plug-ins for simulation methodologies tailored to various metrics and computing resources. We present the design, integration, and deployment of JADE and discuss its potential use for benchmarking AQO programs by the quantum computer science community.
An Integrated Development Environment for Adiabatic Quantum Programming
Humble, Travis S; McCaskey, Alex; Bennink, Ryan S; Billings, Jay Jay; D'Azevedo, Eduardo; Sullivan, Blair D; Klymko, Christine F; Seddiqi, Hadayat
2014-01-01
Adiabatic quantum computing is a promising route to the computational power afforded by quantum information processing. The recent availability of adiabatic hardware raises the question of how well quantum programs perform. Benchmarking behavior is challenging since the multiple steps to synthesize an adiabatic quantum program are highly tunable. We present an adiabatic quantum programming environment called JADE that provides control over all the steps taken during program development. JADE captures the workflow needed to rigorously benchmark performance while also allowing a variety of problem types, programming techniques, and processor configurations. We have also integrated JADE with a quantum simulation engine that enables program profiling using numerical calculation. The computational engine supports plug-ins for simulation methodologies tailored to various metrics and computing resources. We present the design, integration, and deployment of JADE and discuss its use for benchmarking adiabatic quantum programs.
Non-adiabatic molecular dynamics with complex quantum trajectories. II. The adiabatic representation
Zamstein, Noa; Tannor, David J.
2012-12-14
We present a complex quantum trajectory method for treating non-adiabatic dynamics. Each trajectory evolves classically on a single electronic surface but with complex position and momentum. The equations of motion are derived directly from the time-dependent Schroedinger equation, and the population exchange arises naturally from amplitude-transfer terms. In this paper the equations of motion are derived in the adiabatic representation to complement our work in the diabatic representation [N. Zamstein and D. J. Tannor, J. Chem. Phys. 137, 22A517 (2012)]. We apply our method to two benchmark models introduced by John Tully [J. Chem. Phys. 93, 1061 (1990)], and get very good agreement with converged quantum-mechanical calculations. Specifically, we show that decoherence (spatial separation of wavepackets on different surfaces) is already contained in the equations of motion and does not require ad hoc augmentation.
Elastic Moduli Inheritance and Weakest Link in Bulk Metallic Glasses
Stoica, Alexandru Dan; Wang, Xun-Li; Lu, Z.P.; Clausen, Bjorn; Brown, Donald
2012-01-01
We show that a variety of bulk metallic glasses (BMGs) inherit their Young s modulus and shear modulus from the solvent components. This is attributed to preferential straining of locally solvent-rich configurations among tightly bonded atomic clusters, which constitute the weakest link in an amorphous structure. This aspect of inhomogeneous deformation, also revealed by our in-situ neutron diffraction studies of an elastically deformed BMG, suggests a scenario of rubber-like viscoelasticity owing to a hierarchy of atomic bonds in BMGs.
ERIC Educational Resources Information Center
Marine Corps Inst., Washington, DC.
This student guide, one of a series of correspondence training courses designed to improve the job performance of members of the Marine Corps, deals with the skills needed by bulk fuel workers. Addressed in the four individual units of the course are the following topics: bulk fuel equipment, bulk fuel systems, procedures for handling fuels, and…
19 CFR 149.4 - Bulk and break bulk cargo.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 19 Customs Duties 2 2012-04-01 2012-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...
19 CFR 149.4 - Bulk and break bulk cargo.
Code of Federal Regulations, 2010 CFR
2010-04-01
... 19 Customs Duties 2 2010-04-01 2010-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...
19 CFR 149.4 - Bulk and break bulk cargo.
Code of Federal Regulations, 2014 CFR
2014-04-01
... 19 Customs Duties 2 2014-04-01 2014-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...
19 CFR 149.4 - Bulk and break bulk cargo.
Code of Federal Regulations, 2013 CFR
2013-04-01
... 19 Customs Duties 2 2013-04-01 2013-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...
19 CFR 149.4 - Bulk and break bulk cargo.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 19 Customs Duties 2 2011-04-01 2011-04-01 false Bulk and break bulk cargo. 149.4 Section 149.4... TREASURY (CONTINUED) IMPORTER SECURITY FILING § 149.4 Bulk and break bulk cargo. (a) Bulk cargo exempted.... (b) Break bulk cargo exempted from time requirement. For break bulk cargo that is exempt from...
Preliminary Modulus and Breakage Calculations on Cellulose Models
Technology Transfer Automated Retrieval System (TEKTRAN)
The Young’s modulus of polymers can be calculated by stretching molecular models with the computer. The molecule is stretched and the derivative of the changes in stored potential energy for several displacements, divided by the molecular cross-section area, is the stress. The modulus is the slope o...
Effects of EOS adiabat on hot spot dynamics
NASA Astrophysics Data System (ADS)
Cheng, Baolian; Kwan, Thomas; Wang, Yi-Ming; Batha, Steven
2013-10-01
Equation of state (EOS) and adiabat of the pusher play significant roles in the dynamics and formation of the hot spot of an ignition capsule. For given imploding energy, they uniquely determine the partition of internal energy, mass, and volume between the pusher and the hot spot. In this work, we apply the new scaling laws recently derived by Cheng et al. to the National Ignition Campaign (NIC) ignition capsules and study the impacts of EOS and adiabat of the pusher on the hot spot dynamics by using the EOS adiabat index as an adjustable model parameter. We compare our analysis with the NIC data, specifically, for shots N120321 and N120205, and with the numerical simulations of these shots. The predictions from our theoretical model are in good agreements with the NIC data when a hot adiabat was used for the pusher, and with code simulations when a cold adiabat was used for the pusher. Our analysis indicates that the actual adiabat of the pusher in NIC experiments may well be higher than the adiabat assumed in the simulations. This analysis provides a physical and systematic explanation to the ongoing disagreements between the NIC experimental results and the multi-dimensional numerical simulations. This work was performed under the auspices of the U.S. Department of Energy by the Los Alamos National Laboratory under contract number W-7405-ENG-36.
Optimality of partial adiabatic search and its circuit model
NASA Astrophysics Data System (ADS)
Mei, Ying; Sun, Jie; Lu, Songfeng; Gao, Chao
2014-08-01
In this paper, we first uncover a fact that a partial adiabatic quantum search with time complexity is in fact optimal, in which is the total number of elements in an unstructured database, and () of them are the marked ones(one) . We then discuss how to implement a partial adiabatic search algorithm on the quantum circuit model. From the implementing procedure on the circuit model, we can find out that the approximating steps needed are always in the same order of the time complexity of the adiabatic algorithm.
Adiabatic control of atomic dressed states for transport and sensing
NASA Astrophysics Data System (ADS)
Cooper, N. R.; Rey, A. M.
2015-08-01
We describe forms of adiabatic transport that arise for dressed-state atoms in optical lattices. Focusing on the limit of weak tunnel-coupling between nearest-neighbor lattice sites, we explain how adiabatic variation of optical dressing allows control of atomic motion between lattice sites: allowing adiabatic particle transport in a direction that depends on the internal state, and force measurements via spectroscopic preparation and readout. For uniformly filled bands these systems display topologically quantized particle transport. An implementation of the dressing scheme using optical transitions in alkaline-earth atoms is discussed as well as its favorable features for precise force sensing.
NASA Astrophysics Data System (ADS)
Vogt, Bryan; Torres, Jessica; Stafford, Christopher; Register, Richard; Uhrig, David
2012-02-01
We will discuss two systems that significantly impact the thin film behavior with minor changes in chemistry and chain architecture. First, two polymers based on 5-(2-phenylethylnorbornene) are examined. Depending on the polymerization route chosen, the resulting polymer backbone is comprised of either bicyclic (norbornyl) units, which leads to a relatively rigid polymer with a high bulk Tg, or monocyclic (cyclopentyl) units, which leads to a more flexible structure with a lower bulk Tg. The modulus and Tg of the rigid bicyclic polymer is thickness independent down to <10 nm, whereas the modulus of the more flexible monocyclic polymer decreases with decreasing thickness. By hydrogenation of the pendant phenyl ring to the cyclohexyl counterpart, we illustrate that minor changes in the relative flexibility of the side chain do not impact the observed thin film behavior. Second, a series of polystyrene with controlled branching including linear, comb, 6-arm star and centipede. Based upon the molecular mass of the arms, the comb polymer has a significantly larger persistence length and interestingly exhibits only a modest decrease in Tg (9 K) at 5 nm, while the moduli is thickness independent.
Elastic modulus of phases in Ti–Mo alloys
Zhang, Wei-dong; Liu, Yong; Wu, Hong; Song, Min; Zhang, Tuo-yang; Lan, Xiao-dong; Yao, Tian-hang
2015-08-15
In this work, a series of binary Ti–Mo alloys with the Mo contents ranging from 3.2 to 12 at.% were prepared using non-consumable arc melting. The microstructures were investigated by X-ray diffraction and transmission electron microscope, and the elastic modulus was evaluated by nanoindentation testing technique. The evolution of the volume fractions of ω phase was investigated using X-ray photoelectron spectroscopy. The results indicated that the phase constitution and elastic modulus of the Ti–Mo alloys are sensitive to the Mo content. Ti–3.2Mo and Ti–8Mo alloys containing only α and β phases, respectively, have a low elastic modulus. In contrast, Ti–4.5Mo, Ti–6Mo, Ti–7Mo alloys, with different contents of ω phase, have a high elastic modulus. A simple micromechanical model was used to calculate the elastic modulus of ω phase (E{sub ω}), which was determined to be 174.354 GPa. - Highlights: • Ti–Mo alloys with the Mo contents ranging from 3.2 to 12 at.% were investigated. • XPS was used to investigate the volume fractions of ω phase. • The elastic modulus of Ti–Mo alloys is sensitive to the Mo content. • The elastic modulus of ω phase was determined to be 174.354 GPa.
Topological States and Adiabatic Pumping in Quasicrystals
NASA Astrophysics Data System (ADS)
Kraus, Yaakov; Lahini, Yoav; Ringel, Zohar; Verbin, Mor; Zilberberg, Oded
2012-02-01
We find a connection between quasicrystals and topological matter, namely that quasicrystals exhibit non-trivial topological phases attributed to dimensions higher than their own [1]. Quasicrystals are materials which are neither ordered nor disordered, i.e. they exhibit only long-range order [2]. This long-range order is usually expressed as a projection from a higher dimensional ordered system. Recently, the unrelated discovery of Topological Insulators [3] defined a new type of materials classified by their topology. We show theoretically and experimentally using photonic lattices, that one-dimensional quasicrystals exhibit topologically-protected boundary states equivalent to the edge states of the two-dimensional Integer Quantum Hall Effect. We harness this property to adiabatically pump light across the quasicrystal, and generalize our results to higher dimensional systems. Hence, quasicrystals offer a new platform for the study of topological phases while their topology may better explain their surface properties.[4pt] [1] Y. E. Kraus, Y. Lahini, Z. Ringel, M. Verbin, and O. Zilberberg, arXiv:1109.5983 (2011).[0pt] [2] C. Janot, Quasicrystals (Clarendon, Oxford, 1994), 2nd ed.[0pt] [3] M. Z. Hasan and C. L. Kane, Rev. Mod. Phys. 82, 3045 (2010).
On the persistence of adiabatic shear bands
NASA Astrophysics Data System (ADS)
Boakye-Yiadom, S.; Bassim, M. N.; Al-Ameeri, S.
2012-08-01
It is generally agreed that the initiation and development of adiabatic shear bands (ASBs) are manifestations of damage in metallic materials subjected to high strain rates and large strains as those due to impact in a Hopkinson Bar system. Models for evolution of these bands have been described in the literature. One question that has not received attention is how persistent these bands are and whether their presence and effect can be reversed or eliminated by using a process of thermal (heat treatment) or thermo-mechanical treatment that would relieve the material from the high strain associated with ASBs and their role as precursors to crack initiation and subsequent failure. Since ASBs are more prevalent and more defined in BCC metals including steels, a study was conducted to investigate the best conditions of generating ASBs in a heat treatable steel, followed by determining the best conditions for heat treatment of specimens already damaged by the presence of ASBs in order to relieve the strains due to ASBs and restore the material to an apparent microstructure without the "scars" due to the previous presence of ASBs. It was found that heat treatment achieves the curing from ASBs. This presentation documents the process undertaken to achieve this objective.
Adiabatic quantum algorithm for search engine ranking.
Garnerone, Silvano; Zanardi, Paolo; Lidar, Daniel A
2012-06-01
We propose an adiabatic quantum algorithm for generating a quantum pure state encoding of the PageRank vector, the most widely used tool in ranking the relative importance of internet pages. We present extensive numerical simulations which provide evidence that this algorithm can prepare the quantum PageRank state in a time which, on average, scales polylogarithmically in the number of web pages. We argue that the main topological feature of the underlying web graph allowing for such a scaling is the out-degree distribution. The top-ranked log(n) entries of the quantum PageRank state can then be estimated with a polynomial quantum speed-up. Moreover, the quantum PageRank state can be used in "q-sampling" protocols for testing properties of distributions, which require exponentially fewer measurements than all classical schemes designed for the same task. This can be used to decide whether to run a classical update of the PageRank. PMID:23003933
Graph isomorphism and adiabatic quantum computing
NASA Astrophysics Data System (ADS)
Gaitan, Frank; Clark, Lane
2014-03-01
In the Graph Isomorphism (GI) problem two N-vertex graphs G and G' are given and the task is to determine whether there exists a permutation of the vertices of G that preserves adjacency and maps G --> G'. If yes (no), then G and G' are said to be isomorphic (non-isomorphic). The GI problem is an important problem in computer science and is thought to be of comparable difficulty to integer factorization. We present a quantum algorithm that solves arbitrary instances of GI, and which provides a novel approach to determining all automorphisms of a graph. The algorithm converts a GI instance to a combinatorial optimization problem that can be solved using adiabatic quantum evolution. Numerical simulation of the algorithm's quantum dynamics shows that it correctly distinguishes non-isomorphic graphs; recognizes isomorphic graphs; and finds the automorphism group of a graph. We also discuss the algorithm's experimental implementation and show how it can be leveraged to solve arbitrary instances of the NP-Complete Sub-Graph Isomorphism problem.
Design of the PIXIE Adiabatic Demagnetization Refrigerators
NASA Technical Reports Server (NTRS)
Shirron, Peter J.; Kimball, Mark Oliver; Fixsen, Dale J.; Kogut, Alan J.; Li, Xiaoyi; DiPirro, Michael
2012-01-01
The Primordial Inflation Explorer (PIXIE) is a proposed mission to densely map the polarization of the cosmic microwave background. It will operate in a scanning mode from a sun-synchronous orbit, using low temperature detectors (at 0.1 K) and located inside a teslescope that is cooled to approximately 2.73 K - to match the background temperature. A mechanical cryocooler operating at 4.5 K establishes a low base temperature from which two adiabatic demagnetization refrigerator (ADR) assemblies will cool the telescope and detectors. To achieve continuous scanning capability, the ADRs must operate continuously. Complicating the design are two factors: 1) the need to systematically vary the temperature of various telescope components in order to separate the small polarization signal variations from those that may arise from temperature drifts and changing gradients within the telescope, and 2) the orbital and monthly variations in lunar irradiance into the telescope barrels. These factors require the telescope ADR to reject quasi-continuous heat loads of 2-3 millwatts, while maintaining a peak heat reject rate of less than 12 milliwatts. The detector heat load at 0.1 K is comparatively small at 1-2 microwatts. This paper will describe the 3-stage and 2-stage continuous ADRs that will be used to meet the cooling power and temperature stability requirements of the PIXIE detectors and telescope.
Quasi-Maximum Modulus Principle for the Stokes Equations
NASA Astrophysics Data System (ADS)
Chang, Tongkeun; Choe, Hi Jun
2016-06-01
In this paper, we extend the maximum modulus estimate of the solutions of the nonstationary Stokes equations in the bounded C 2 cylinders for the space variables in Chang and Choe (J Differ Equ 254(7):2682-2704, 2013) to time estimate. We show that if the boundary data is {L^{∞}} and the normal part of the boundary data has log-Dini continuity with respect to the time, then the velocity is bounded. We emphasize that there is no continuity assumption on space variables in the new maximum modulus estimate. This completes the maximum modulus estimate.
Adiabaticity and spectral splits in collective neutrino transformations
Raffelt, Georg G.; Smirnov, Alexei Yu.
2007-12-15
Neutrinos streaming off a supernova core transform collectively by neutrino-neutrino interactions, leading to 'spectral splits' where an energy E{sub split} divides the transformed spectrum sharply into parts of almost pure but different flavors. We present a detailed description of the spectral-split phenomenon which is conceptually and quantitatively understood in an adiabatic treatment of neutrino-neutrino effects. Central to this theory is a self-consistency condition in the form of two sum rules (integrals over the neutrino spectra that must equal certain conserved quantities). We provide explicit analytic and numerical solutions for various neutrino spectra. We introduce the concept of the adiabatic reference frame and elaborate on the relative adiabatic evolution. Violating adiabaticity leads to the spectral split being 'washed out'. The sharpness of the split appears to be represented by a surprisingly universal function.
Adiabatic rotation, quantum search, and preparation of superposition states
NASA Astrophysics Data System (ADS)
Siu, M. Stewart
2007-06-01
We introduce the idea of using adiabatic rotation to generate superpositions of a large class of quantum states. For quantum computing this is an interesting alternative to the well-studied “straight line” adiabatic evolution. In ways that complement recent results, we show how to efficiently prepare three types of states: Kitaev’s toric code state, the cluster state of the measurement-based computation model, and the history state used in the adiabatic simulation of a quantum circuit. We also show that the method, when adapted for quantum search, provides quadratic speedup as other optimal methods do with the advantages that the problem Hamiltonian is time independent and that the energy gap above the ground state is strictly nondecreasing with time. Likewise the method can be used for optimization as an alternative to the standard adiabatic algorithm.
Coherent transfer by adiabatic passage in two-dimensional lattices
Longhi, Stefano
2014-09-15
Coherent tunneling by adiabatic passage (CTAP) is a well-established technique for robust spatial transport of quantum particles in linear chains. Here we introduce two exactly-solvable models where the CTAP protocol can be extended to two-dimensional lattice geometries. Such bi-dimensional lattice models are synthesized from time-dependent second-quantization Hamiltonians, in which the bosonic field operators evolve adiabatically like in an ordinary three-level CTAP scheme thus ensuring adiabatic passage in Fock space. - Highlights: • New ways of coherent transport by adiabatic passage (CTAP) in 2D lattices. • Synthesis of exactly-solvable 2D lattices from a simple three-well model. • CTAP in 2D lattices can be exploited for quantum state transfer.
Adiabatic and isocurvature perturbation projections in multi-field inflation
Gordon, Chris; Saffin, Paul M. E-mail: Paul.Saffin@nottingham.ac.uk
2013-08-01
Current data are in good agreement with the predictions of single field inflation. However, the hemispherical asymmetry, seen in the cosmic microwave background data, may hint at a potential problem. Generalizing to multi-field models may provide one possible explanation. A useful way of modeling perturbations in multi-field inflation is to investigate the projection of the perturbation along and perpendicular to the background fields' trajectory. These correspond to the adiabatic and isocurvature perturbations. However, it is important to note that in general there are no corresponding adiabatic and isocurvature fields. The purpose of this article is to highlight the distinction between a field redefinition and a perturbation projection. We provide a detailed derivation of the evolution of the isocurvature perturbation to show that no assumption of an adiabatic or isocurvature field is needed. We also show how this evolution equation is consistent with the field covariant evolution equations for the adiabatic perturbation in the flat field space limit.
Ultrafast stimulated Raman parallel adiabatic passage by shaped pulses
Dridi, G.; Guerin, S.; Hakobyan, V.; Jauslin, H. R.; Eleuch, H.
2009-10-15
We present a general and versatile technique of population transfer based on parallel adiabatic passage by femtosecond shaped pulses. Their amplitude and phase are specifically designed to optimize the adiabatic passage corresponding to parallel eigenvalues at all times. We show that this technique allows the robust adiabatic population transfer in a Raman system with the total pulse area as low as 3{pi}, corresponding to a fluence of one order of magnitude below the conventional stimulated Raman adiabatic passage process. This process of short duration, typically picosecond and subpicosecond, is easily implementable with the modern pulse shaper technology and opens the possibility of ultrafast robust population transfer with interesting applications in quantum information processing.
Adiabatic invariant value variation under shortwave band subcritical conditions
NASA Astrophysics Data System (ADS)
Svistunov, K. V.; Tinin, M. V.
1985-04-01
The possibility of significant variations of the adiabatic invariant is examined for the propagation of radio waves in an irregular Earth-ionosphere waveguide with a parabolic dependence of permittivity on height. Numerical and analytical results indicate that nonexponential deviations of the adiabatic invariant can occur not only when the characteristic size of horizontal irregularity decreases (e.g., during resonant beam excitation) but also in quasi-critical conditions and for smoothly irregular waveguides.
Shortcuts to adiabaticity for non-Hermitian systems
Ibanez, S.; Martinez-Garaot, S.; Torrontegui, E.; Muga, J. G.; Chen Xi
2011-08-15
Adiabatic processes driven by non-Hermitian, time-dependent Hamiltonians may be sped up by generalizing inverse engineering techniques based on counter-diabatic (transitionless driving) algorithms or on dynamical invariants. We work out the basic theory and examples described by two-level Hamiltonians: the acceleration of rapid adiabatic passage with a decaying excited level and of the dynamics of a classical particle on an expanding harmonic oscillator.
Frequency-dependent complex modulus of the uterus: preliminary results
NASA Astrophysics Data System (ADS)
Kiss, Miklos Z.; Hobson, Maritza A.; Varghese, Tomy; Harter, Josephine; Kliewer, Mark A.; Hartenbach, Ellen M.; Zagzebski, James A.
2006-08-01
The frequency-dependent complex moduli of human uterine tissue have been characterized. Quantification of the modulus is required for developing uterine ultrasound elastography as a viable imaging modality for diagnosing and monitoring causes for abnormal uterine bleeding and enlargement, as well assessing the integrity of uterine and cervical tissue. The complex modulus was measured in samples from hysterectomies of 24 patients ranging in age from 31 to 79 years. Measurements were done under small compressions of either 1 or 2%, at low pre-compression values (either 1 or 2%), and over a frequency range of 0.1-100 Hz. Modulus values of cervical tissue monotonically increased from approximately 30-90 kPa over the frequency range. Normal uterine tissue possessed modulus values over the same range, while leiomyomas, or uterine fibroids, exhibited values ranging from approximately 60-220 kPa.
Analyzing cements and completion gels using dynamic modulus
Lacy, L.L.; Rickards, A.
1996-12-31
The measurement and control of the physical properties of completion fluids are important problems to the oil and gas industry. A new laboratory instrument, a dynamic modulus analyzer (DMA), has been developed that analyses the physical and mechanical properties of fluids and cement slurries under downhole conditions by using high resolution ultrasonics. A dynamic modulus analyzer can measure compressive strength, dynamic Young`s modulus, and the shrinkage or expansion of cements. The DMA can also be used to determine viscosity changes and changes in the density of fracturing and completion gels under static (10{sup -4} s{sup -1}) or zero shear conditions. Test data indicate the DMA is 20 to 100 times more sensitive than current laboratory instruments in evaluating changes in cements or gel properties. Cement shrinkage was measured simultaneously with compressive strength and dynamic modulus. The times required to achieve maximum gel strength and gel breaking were also determined for Fracturing gels and a temporary blocking gel.
Lithium: Measurement of Young's Modulus and Yield Strength
Ryan P Schultz
2002-11-07
The Lithium Collection Lens is used for anti-proton collection. In analyzing the structural behavior during operation, various material properties of lithium are often needed. properties such as density, coefficient of thermal expansion, thermal conductivity, specific heat, compressability, etc.; are well known. However, to the authors knowledge there is only one published source for Young's Modulus. This paper reviews the results from the testing of Young's Modulus and the yield strength of lithium at room temperature.
New insights into the Young's modulus of staggered biological composites.
Bar-On, Benny; Wagner, H Daniel
2013-03-01
This communication presents a simplified "mechanics-of-materials" approach for describing the mechanics of staggered composite architectures, such as those arising in a variety of biological tissues. This analysis calculates the effective modulus of the bio-composite and provides physical insights into its elastic behavior. Simplified expressions for high- and low-mineralized tissues are then proposed and the effects of the mineral thickness ratio and aspect ratio on the modulus are demonstrated.
Non-toxic invert analog glass compositions of high modulus
NASA Technical Reports Server (NTRS)
Bacon, J. F. (Inventor)
1974-01-01
Glass compositions having a Young's modulus of at least 15 million psi are described. They and a specific modulus of at least 110 million inches consist essentially of, in mols, 15 to 40% SiO2, 6 to 15% Li2O, 24 to 45% of at least two bivalent oxides selected from the group consisting of Ca, NzO, MgO and CuO; 13 to 39% of at least two trivalent oxides selected from the group consisting of Al2O3, Fe2O3, B2O3, La2O3, and Y2O3 and up to 15% of one or more tetravelent oxides selected from the group consisting of ZrO2, TiO2 and CeO2. The high modulus, low density glass compositions contain no toxic elements. The composition, glass density, Young's modulus, and specific modulus for 28 representative glasses are presented. The fiber modulus of five glasses are given.
Berryman, J G
2005-03-23
To provide quantitative measures of the importance of fluid effects on shear waves in heterogeneous reservoirs, a model material called a ''random polycrystal of porous laminates'' is introduced. This model poroelastic material has constituent grains that are layered (or laminated), and each layer is an isotropic, microhomogeneous porous medium. All grains are composed of exactly the same porous constituents, and have the same relative volume fractions. The order of lamination is not important because the up-scaling method used to determine the transversely isotropic (hexagonal) properties of the grains is Backus averaging, which--for quasi-static or long-wavelength behavior--depends only on the volume fractions and layer properties. Grains are then jumbled together totally at random, filling all space, and producing an overall isotropic poroelastic medium. The poroelastic behavior of this medium is then analyzed using the Peselnick-Meister-Watt bounds (of Hashin-Shtrikman type). We study the dependence of the shear modulus on pore fluid properties and determine the range of behavior to be expected. In particular we compare and contrast these results to those anticipated from Gassmann's fluid substitution formulas, and to the predictions of Mavko and Jizba for very low porosity rocks with flat cracks. This approach also permits the study of arbitrary numbers of constituents, but for simplicity the numerical examples are restricted here to just two constituents. This restriction also permits the use of some special exact results available for computing the overall effective stress coefficient in any two-component porous medium. The bounds making use of polycrystalline microstructure are very tight. Results for the shear modulus demonstrate that the ratio of compliance differences R (i.e., shear compliance changes over bulk compliance changes when going from drained to undrained behavior, or vice versa) is usually nonzero and can take a wide range of values, both
Meta-GGA-based adiabatic time-dependent density-functional theory
NASA Astrophysics Data System (ADS)
Nazarov, Vladimir; Vignale, Giovanni
2012-02-01
The local-density approximation (LDA) to the ground-state density functional theory (DFT) is well known to allow for a generalization to the time-dependent case [1]. The assumption of the adiabaticity of the process greatly simplifies the theory. The further extension of the time-dependent DFT (TDDFT) to the generalized gradient approximation (GGA) is trivial. Here we address lifting the adiabatic TDDFT to the third rung of the ``Jacobs ladder'' [2] : We work out the kinetic energy density dependent (meta-GGA) TDDFT formalism. The new theory possesses remarkable properties not present in LDA and GGA: (i) It is non-local with respect to the particle density; (ii) In the case of bulk semiconductors, it supports the 1/q^2 singularity of the exchange-correlation kernel, where q is the wave-vector, the latter being important to reproduce the excitonic effect. We also present illustrative calculations of the optical absorption in semiconductors [3]. [4pt] [1] A. Zangwill and P. Soven, Phys. Rev. A, 21, 1561 (1980).[0pt] [2] J. Tao, J. P. Perdew, V. N. Staroverov, and G. E. Scuseria, Phys. Rev. Lett. 91, 146401 (2003).[0pt] [3] V. U. Nazarov and G. Vignale, Phys. Rev. Lett. 107, 216402(2011).
Large area bulk superconductors
Miller, Dean J.; Field, Michael B.
2002-01-01
A bulk superconductor having a thickness of not less than about 100 microns is carried by a polycrystalline textured substrate having misorientation angles at the surface thereof not greater than about 15.degree.; the bulk superconductor may have a thickness of not less than about 100 microns and a surface area of not less than about 50 cm.sup.2. The textured substrate may have a thickness not less than about 10 microns and misorientation angles at the surface thereof not greater than about 15.degree.. Also disclosed is a process of manufacturing the bulk superconductor and the polycrystalline biaxially textured substrate material.
NASA Astrophysics Data System (ADS)
Pabst, Oliver; Schiffer, Michael; Obermeier, Ernst; Tekin, Tolga; Lang, Klaus Dieter; Ngo, Ha-Duong
2011-06-01
Silicon carbide (SiC) is a promising material for applications in harsh environments. Standard silicon (Si) microelectromechanical systems (MEMS) are limited in operating temperature to temperatures below 130 °C for electronic devices and below 600 °C for mechanical devices. Due to its large bandgap SiC enables MEMS with significantly higher operating temperatures. Furthermore, SiC exhibits high chemical stability and thermal conductivity. Young's modulus and residual stress are important mechanical properties for the design of sophisticated SiC-based MEMS devices. In particular, residual stresses are strongly dependent on the deposition conditions. Literature values for Young's modulus range from 100 to 400 GPa, and residual stresses range from 98 to 486 MPa. In this paper we present our work on investigating Young's modulus and residual stress of SiC films deposited on single crystal bulk silicon using bulge testing. This method is based on measurement of pressure-dependent membrane deflection. Polycrystalline as well as single crystal cubic silicon carbide samples are studied. For the samples tested, average Young's modulus and residual stress measured are 417 GPa and 89 MPa for polycrystalline samples. For single crystal samples, the according values are 388 GPa and 217 MPa. These results compare well with literature values.
Variable modulus cellular structures using pneumatic artificial muscles
NASA Astrophysics Data System (ADS)
Pontecorvo, Michael E.; Niemiec, Robert J.; Gandhi, Farhan S.
2014-04-01
This paper presents a novel variable modulus cellular structure based on a hexagonal unit cell with pneumatic artificial muscle (PAM) inclusions. The cell considered is pin-jointed, loaded in the horizontal direction, with three PAMs (one vertical PAM and two horizontal PAMs) oriented in an "H" configuration between the vertices of the cell. A method for calculation of the hexagonal cell modulus is introduced, as is an expression for the balance of tensile forces between the horizontal and vertical PAMs. An aluminum hexagonal unit cell is fabricated and simulation of the hexagonal cell with PAM inclusions is then compared to experimental measurement of the unit cell modulus in the horizontal direction with all three muscles pressurized to the same value over a pressure range up to 758 kPa. A change in cell modulus by a factor of 1.33 and a corresponding change in cell angle of 0.41° are demonstrated experimentally. A design study via simulation predicts that differential pressurization of the PAMs up to 2068 kPa can change the cell modulus in the horizontal direction by a factor of 6.83 with a change in cell angle of only 2.75°. Both experiment and simulation show that this concept provides a way to decouple the length change of a PAM from the change in modulus to create a structural unit cell whose in-plane modulus in a given direction can be tuned based on the orientation of PAMs within the cell and the pressure supplied to the individual muscles.
Factors that influence muscle shear modulus during passive stretch.
Koo, Terry K; Hug, François
2015-09-18
Although elastography has been increasingly used for evaluating muscle shear modulus associated with age, sex, musculoskeletal, and neurological conditions, its physiological meaning is largely unknown. This knowledge gap may hinder data interpretation, limiting the potential of using elastography to gain insights into muscle biomechanics in health and disease. We derived a mathematical model from a widely-accepted Hill-type passive force-length relationship to gain insight about the physiological meaning of resting shear modulus of skeletal muscles under passive stretching, and validated the model by comparing against the ex-vivo animal data reported in our recent work (Koo et al. 2013). The model suggested that resting shear modulus of a slack muscle is a function of specific tension and parameters that govern the normalized passive muscle force-length relationship as well as the degree of muscle anisotropy. The model also suggested that although the slope of the linear shear modulus-passive force relationship is primarily related to muscle anatomical cross-sectional area (i.e. the smaller the muscle cross-sectional area, the more the increase in shear modulus to result in the same passive muscle force), it is also governed by the normalized passive muscle force-length relationship and the degree of muscle anisotropy. Taken together, although muscle shear modulus under passive stretching has a strong linear relationship with passive muscle force, its actual value appears to be affected by muscle's mechanical, material, and architectural properties. This should be taken into consideration when interpreting the muscle shear modulus values. PMID:26113291
Factors that influence muscle shear modulus during passive stretch.
Koo, Terry K; Hug, François
2015-09-18
Although elastography has been increasingly used for evaluating muscle shear modulus associated with age, sex, musculoskeletal, and neurological conditions, its physiological meaning is largely unknown. This knowledge gap may hinder data interpretation, limiting the potential of using elastography to gain insights into muscle biomechanics in health and disease. We derived a mathematical model from a widely-accepted Hill-type passive force-length relationship to gain insight about the physiological meaning of resting shear modulus of skeletal muscles under passive stretching, and validated the model by comparing against the ex-vivo animal data reported in our recent work (Koo et al. 2013). The model suggested that resting shear modulus of a slack muscle is a function of specific tension and parameters that govern the normalized passive muscle force-length relationship as well as the degree of muscle anisotropy. The model also suggested that although the slope of the linear shear modulus-passive force relationship is primarily related to muscle anatomical cross-sectional area (i.e. the smaller the muscle cross-sectional area, the more the increase in shear modulus to result in the same passive muscle force), it is also governed by the normalized passive muscle force-length relationship and the degree of muscle anisotropy. Taken together, although muscle shear modulus under passive stretching has a strong linear relationship with passive muscle force, its actual value appears to be affected by muscle's mechanical, material, and architectural properties. This should be taken into consideration when interpreting the muscle shear modulus values.
Lattice Thermal Conductivity of Superlattices from an Adiabatic Bond Charge Model
NASA Astrophysics Data System (ADS)
Ward, Alistair; Broido, David
2007-03-01
The adiabatic bond charge model (ABCM) has successfully rendered phonon dispersions of a host of bulk semiconductors [1,2] and has also been used to calculate the phonon dispersions in quantum well superlattices [3]. We have developed an ABCM for superlattices and combined it with a symmetry-based representation of the anharmonic interatomic forces to calculate the lattice thermal conductivity of short-period superlattices, using an iterative solution to the Boltzmann-Peierls equation [4]. We compare our ABCM results with those obtained from some commonly used models for the interatomic forces in semiconductors to assess the importance of accurate descriptions of the phonon dispersions in thermal conductivity calculations. [1] W. Weber, Physical Review B 15, 4789 (1977). [2] K. C. Rustagi and W. Weber, Solid State Communications 18, 673 (1976). [3] S. K. Yip and Y. C. Chang, Physical Review B 30 7037 (1984). [4] D. A. Broido, A. Ward, and N. Mingo, Physical Review B 72, 014308 (2005).
LETTERS AND COMMENTS: Adiabatic process reversibility: microscopic and macroscopic views
NASA Astrophysics Data System (ADS)
Anacleto, Joaquim; Pereira, Mário G.
2009-05-01
The reversibility of adiabatic processes was recently addressed by two publications. In the first (Miranda 2008 Eur. J. Phys. 29 937-43), an equation was derived relating the initial and final volumes and temperatures for adiabatic expansions of an ideal gas, using a microscopic approach. In that relation the parameter r accounts for the process reversibility, ranging between 0 and 1, which corresponds to the free and reversible expansion, respectively. In the second (Anacleto and Pereira 2009 Eur. J. Phys. 30 177-83), the authors have shown that thermodynamics can effectively and efficiently be used to obtain the general law for adiabatic processes carried out by an ideal gas, including compressions, for which r \\ge 1. The present work integrates and extends the aforementioned studies, providing thus further insights into the analysis of the adiabatic process. It is shown that Miranda's work is wholly valid for compressions. In addition, it is demonstrated that the adiabatic reversibility coefficient given in terms of the piston velocity and the root mean square velocity of the gas particles is equivalent to the macroscopic description, given just by the quotient between surroundings and system pressure values.
Adiabatic continuity, wave-function overlap, and topological phase transitions
NASA Astrophysics Data System (ADS)
Gu, Jiahua; Sun, Kai
2016-09-01
In this paper, we study the relation between wave-function overlap and adiabatic continuity in gapped quantum systems. We show that for two band insulators, a scalar function can be defined in the momentum space, which characterizes the wave-function overlap between Bloch states in the two insulators. If this overlap is nonzero for all momentum points in the Brillouin zone, these two insulators are adiabatically connected, i.e., we can deform one insulator into the other smoothly without closing the band gap. In addition, we further prove that this adiabatic path preserves all the symmetries of the insulators. The existence of such an adiabatic path implies that two insulators with nonzero wave-function overlap belong to the same topological phase. This relation, between adiabatic continuity and wave-function overlap, can be further generalized to correlated systems. The generalized relation cannot be applied to study generic many-body systems in the thermodynamic limit, because of the orthogonality catastrophe. However, for certain interacting systems (e.g., quantum Hall systems), the quantum wave-function overlap can be utilized to distinguish different quantum states. Experimental implications are also discussed.
Adiabatic condition and the quantum hitting time of Markov chains
Krovi, Hari; Ozols, Maris; Roland, Jeremie
2010-08-15
We present an adiabatic quantum algorithm for the abstract problem of searching marked vertices in a graph, or spatial search. Given a random walk (or Markov chain) P on a graph with a set of unknown marked vertices, one can define a related absorbing walk P{sup '} where outgoing transitions from marked vertices are replaced by self-loops. We build a Hamiltonian H(s) from the interpolated Markov chain P(s)=(1-s)P+sP{sup '} and use it in an adiabatic quantum algorithm to drive an initial superposition over all vertices to a superposition over marked vertices. The adiabatic condition implies that, for any reversible Markov chain and any set of marked vertices, the running time of the adiabatic algorithm is given by the square root of the classical hitting time. This algorithm therefore demonstrates a novel connection between the adiabatic condition and the classical notion of hitting time of a random walk. It also significantly extends the scope of previous quantum algorithms for this problem, which could only obtain a full quadratic speedup for state-transitive reversible Markov chains with a unique marked vertex.
Role of gradients in vocal fold elastic modulus on phonation
Bhattacharya, Pinaki; Kelleher, Jordan E.; Siegmund, Thomas
2015-01-01
New studies show that the elastic properties of the vocal folds (VFs) vary locally. In particular strong gradients exist in the distribution of elastic modulus along the length of the VF ligament, which is an important load-bearing constituent of the VF tissue. There is further evidence that changes in VF health are associated with alterations in modulus gradients. The role of VF modulus gradation on VF vibration and phonation remains unexplored. In this study the magnitude of the gradient in VF elastic modulus is varied, and sophisticated computational simulations are performed of the self-oscillation of three-dimensional VFs with realistic modeling of airflow physical properties. Results highlight that phonation frequency, characteristic modes of deformation and phase differences, glottal airflow rate, spectral-width of vocal output, and glottal jet dynamics are dependent on the magnitude of VF elastic modulus gradation. The results advance the understanding of how VF functional gradation can lead to perceptible changes in speech quality. PMID:26159059
Shortcuts to adiabaticity in a time-dependent box
Campo, A. del; Boshier, M. G.
2012-01-01
A method is proposed to drive an ultrafast non-adiabatic dynamics of an ultracold gas trapped in a time-dependent box potential. The resulting state is free from spurious excitations associated with the breakdown of adiabaticity, and preserves the quantum correlations of the initial state up to a scaling factor. The process relies on the existence of an adiabatic invariant and the inversion of the dynamical self-similar scaling law dictated by it. Its physical implementation generally requires the use of an auxiliary expulsive potential. The method is extended to a broad family of interacting many-body systems. As illustrative examples we consider the ultrafast expansion of a Tonks-Girardeau gas and of Bose-Einstein condensates in different dimensions, where the method exhibits an excellent robustness against different regimes of interactions and the features of an experimentally realizable box potential. PMID:22970340
Shortcuts to adiabaticity in a time-dependent box.
del Campo, A; Boshier, M G
2012-01-01
A method is proposed to drive an ultrafast non-adiabatic dynamics of an ultracold gas trapped in a time-dependent box potential. The resulting state is free from spurious excitations associated with the breakdown of adiabaticity, and preserves the quantum correlations of the initial state up to a scaling factor. The process relies on the existence of an adiabatic invariant and the inversion of the dynamical self-similar scaling law dictated by it. Its physical implementation generally requires the use of an auxiliary expulsive potential. The method is extended to a broad family of interacting many-body systems. As illustrative examples we consider the ultrafast expansion of a Tonks-Girardeau gas and of Bose-Einstein condensates in different dimensions, where the method exhibits an excellent robustness against different regimes of interactions and the features of an experimentally realizable box potential.
Shortcuts to adiabaticity in a time-dependent box
NASA Astrophysics Data System (ADS)
Del Campo, A.; Boshier, M. G.
2012-09-01
A method is proposed to drive an ultrafast non-adiabatic dynamics of an ultracold gas trapped in a time-dependent box potential. The resulting state is free from spurious excitations associated with the breakdown of adiabaticity, and preserves the quantum correlations of the initial state up to a scaling factor. The process relies on the existence of an adiabatic invariant and the inversion of the dynamical self-similar scaling law dictated by it. Its physical implementation generally requires the use of an auxiliary expulsive potential. The method is extended to a broad family of interacting many-body systems. As illustrative examples we consider the ultrafast expansion of a Tonks-Girardeau gas and of Bose-Einstein condensates in different dimensions, where the method exhibits an excellent robustness against different regimes of interactions and the features of an experimentally realizable box potential.
Effect of dephasing on stimulated Raman adiabatic passage
Ivanov, P.A.; Vitanov, N.V.; Bergmann, K.
2004-12-01
This work explores the effect of phase relaxation on the population transfer efficiency in stimulated Raman adiabatic passage (STIRAP). The study is based on the Liouville equation, which is solved analytically in the adiabatic limit. The transfer efficiency of STIRAP is found to decrease exponentially with the dephasing rate; this effect is stronger for shorter pulse delays and weaker for larger delays, since the transition time is found to be inversely proportional to the pulse delay. Moreover, it is found that the transfer efficiency of STIRAP in the presence of dephasing does not depend on the peak Rabi frequencies at all, as long as they are sufficiently large to enforce adiabatic evolution; hence increasing the field intensity cannot reduce the dephasing losses. It is shown also that for any dephasing rate, the final populations of the initial state and the intermediate state are equal. For strong dephasing all three populations tend to (1/3)
Design of a photonic lattice using shortcuts to adiabaticity
NASA Astrophysics Data System (ADS)
Stefanatos, Dionisis
2014-08-01
In this article we use the method of shortcuts to adiabaticity to design a photonic lattice (array of waveguides) which can drive the input light to a controlled location at the output. The output position in the array is determined by functions of the propagation distance along the waveguides, which modulate the lattice characteristics (index of refraction, and first- and second-neighbor couplings). The proposed coupler is expected to possess the robustness properties of the design method, coming from its adiabatic nature, and also to have a smaller footprint than purely adiabatic couplers. The present work provides a very interesting example where methods from quantum control can be exploited to design lattices with desired input-output properties.
Adiabatic Quantum Programming: Minor Embedding With Hard Faults
Klymko, Christine F; Sullivan, Blair D; Humble, Travis S
2013-01-01
Adiabatic quantum programming defines the time-dependent mapping of a quantum algorithm into the hardware or logical fabric. An essential programming step is the embedding of problem-specific information into the logical fabric to define the quantum computational transformation. We present algorithms for embedding arbitrary instances of the adiabatic quantum optimization algorithm into a square lattice of specialized unit cells. Our methods are shown to be extensible in fabric growth, linear in time, and quadratic in logical footprint. In addition, we provide methods for accommodating hard faults in the logical fabric without invoking approximations to the original problem. These hard fault-tolerant embedding algorithms are expected to prove useful for benchmarking the adiabatic quantum optimization algorithm on existing quantum logical hardware. We illustrate this versatility through numerical studies of embeddabilty versus hard fault rates in square lattices of complete bipartite unit cells.
Adiabatic Quantum Computation and the Theory of Quantum Phase Transitions
NASA Astrophysics Data System (ADS)
Kaminsky, William; Lloyd, Seth
2007-03-01
We present a general approach to determining the asymptotic scaling of adiabatic quantum computational resources (space, time, energy, and precision) on random instances of NP-complete graph theory problems. By utilizing the isomorphisms between certain NP-complete graph theory problems and certain frustrated spin models, we demonstrate that the asymptotic scaling of the minimum spectral gap that determines the asymptotic running time of adiabatic algorithms is itself determined by the presence and character of quantum phase transitions in these frustrated models. Most notably, we draw the conclusion that adiabatic quantum computers based on quantum Ising models are much less likely to be efficient than those based on quantum rotor or Heisenberg models. We then exhibit practical rotor and Heisenberg model based architectures using Josephson junction and quantum dot circuits.
NASA Astrophysics Data System (ADS)
Bačić, Z.
1991-09-01
We show that the triatomic adiabatic vibrational eigenstates (AVES) provide a convenient basis for accurate discrete variable representation (DVR) calculation and automatic assignment of highly excited, large amplitude motion vibrational states of floppy triatomic molecules. The DVR-AVES states are eigenvectors of the diagonal (in the stretch states) blocks of the adiabatically rearranged triatomic DVR-ray eigenvector (DVR-REV) Hamiltonian [J. C. Light and Z. Bačić, J. Chem. Phys. 87, 4008 (1987)]. The transformation of the full triatomic vibrational Hamiltonian from the DVR-REV basis to the new DVR-AVES basis is simple, and does not involve calculation of any new matrix elements. No dynamical approximation is made in the energy level calculation by the DVR-AVES approach; its accuracy and efficiency are identical to those of the DVR-REV method. The DVR-AVES states, as the adiabatic approximation to the vibrational states of a triatomic molecule, are labeled by three vibrational quantum numbers. Consequently, accurate large amplitude motion vibrational levels obtained by diagonalizing the full vibrational Hamiltonian transformed to the DVR-AVES basis, can be assigned automatically by the code, with the three quantum numbers of the dominant DVR-AVES state associated with the largest (by modulus) eigenvector element in the DVR-AVES basis. The DVR-AVES approach is used to calculate accurate highly excited localized and delocalized vibrational levels of HCN/HNC and LiCN/LiNC. A significant fraction of localized states of both systems, below and above the isomerization barrier, is assigned automatically, without inspection of wave function plots or separate approximate calculations.
Determination of the elastic modulus of snow via acoustic measurements
NASA Astrophysics Data System (ADS)
Gerling, Bastian; van Herwijnen, Alec; Löwe, Henning
2016-04-01
The elastic modulus of snow is a key quantity from the viewpoint of avalanche research and forecasting, snow engineering or materials science in general. Since it is a fundamental property, many measurements have been reported in the literature. Due to differences in measurement methods, there is a lot of variation in the reported values. Especially values derived via computer tomography (CT) based numerical calculations using finite element methods are not corresponding to the results of other methods. The central issue is that CT based moduli are purely elastic whereas other methods may include viscoelastic deformation. In order to avoid this discrepancy we derived the elastic modulus of snow via wave propagation measurements and compared our results with CT based calculations. We measured the arrival times of acoustic pulses propagating through the snow samples to determine the P-wave velocity and in turn derive the elastic modulus along the direction of wave propagation. We performed a series of laboratory experiments to derive the P-wave modulus of snow in relation to density. The P-wave modulus ranged from 10 to 280 MPa for a snow density between 150 and 370 kg/m^3;. The moduli derived from the acoustic measurements correlated well with the CT-based values and both exhibited a power law trend over the entire density range. Encouraged by these results we used the acoustic method to investigate the temporal evolution of the elastic modulus. The rate of increase was very close to values mentioned in literature on the sintering rate of snow. Overall, our results are a first but important step towards a new measurement method to attain the elastic properties of snow.
Consolidation trend design based on Young's modulus of clarithromycin single crystals.
Janković, B; Skarabot, M; Lavrič, Z; Ilić, I; Muševič, I; Srčič, S; Planinšek, O
2013-09-15
The key aim of this study was to determine single mechanical properties of clarithromycin polymorphic forms in order to select some of them as more suitable for the tableting process. For this purpose, AFM single-point nanoindentation was used. The Young's moduli of clarithromycin polymorphs were substantially different, which was consistent with the structural variations in their packing motifs. The presence of the adjacent layers, which can easily slide over each other due to the low energy barrier (the lowest Young's modulus was 0.25 GPa) resulted in better bulk compressibility (the highest Heckel coefficient) of clarithromycin Form I. We also addressed the importance of tip geometry screening because the stress during the force mode often results in tip apex fracture. Even the initial manufacture of the diamond-coated tips can result in defects such as double-apex tips.
Global adiabaticity and non-Gaussianity consistency condition
NASA Astrophysics Data System (ADS)
Romano, Antonio Enea; Mooij, Sander; Sasaki, Misao
2016-10-01
In the context of single-field inflation, the conservation of the curvature perturbation on comoving slices, Rc, on super-horizon scales is one of the assumptions necessary to derive the consistency condition between the squeezed limit of the bispectrum and the spectrum of the primordial curvature perturbation. However, the conservation of Rc holds only after the perturbation has reached the adiabatic limit where the constant mode of Rc dominates over the other (usually decaying) mode. In this case, the non-adiabatic pressure perturbation defined in the thermodynamic sense, δPnad ≡ δP - cw2 δρ where cw2 = P ˙ / ρ ˙ , usually becomes also negligible on superhorizon scales. Therefore one might think that the adiabatic limit is the same as thermodynamic adiabaticity. This is in fact not true. In other words, thermodynamic adiabaticity is not a sufficient condition for the conservation of Rc on super-horizon scales. In this paper, we consider models that satisfy δPnad = 0 on all scales, which we call global adiabaticity (GA), which is guaranteed if cw2 = cs2, where cs is the phase velocity of the propagation of the perturbation. A known example is the case of ultra-slow-roll (USR) inflation in which cw2 = cs2 = 1. In order to generalize USR we develop a method to find the Lagrangian of GA K-inflation models from the behavior of background quantities as functions of the scale factor. Applying this method we show that there indeed exists a wide class of GA models with cw2 = cs2, which allows Rc to grow on superhorizon scales, and hence violates the non-Gaussianity consistency condition.
Determination of Young's modulus of silica aerogels using holographic interferometry
NASA Astrophysics Data System (ADS)
Chikode, Prashant P.; Sabale, Sandip R.; Vhatkar, Rajiv S.
2016-05-01
Digital holographic interferometry technique is used to determine elastic modulus of silica aerogels. Tetramethoxysilane precursor based Silica aerogels were prepared by the sol-gel process followed by supercritical methanol drying. The alcogels were prepared by keeping the molar ratio of tetramethoxysilane: methyltrimethoxysilane: H2O constant at 1:0.6:4 while the methanol / tetramethoxysilane molar ratio (M) was varied systematically from 12 to 18. Holograms of translucent aerogel samples have been successfully recorded using the digital holographic interferometry technique. Stimulated digital interferograms gives localization of interference fringes on the aerogel surface and these fringes are used to determine the surface deformation and Young's modulus (Y) of the aerogels.
Bending modulus of bidisperse particle rafts: Local and collective contributions.
Petit, Pauline; Biance, Anne-Laure; Lorenceau, Elise; Planchette, Carole
2016-04-01
The bending modulus of air-water interfaces covered by a monolayer of bidisperse particles is probed experimentally under quasistatic conditions via the compression of the monolayer, and under dynamical conditions studying capillary-wave propagation. Simple averaging of the modulus obtained solely with small or large particles fails to describe our data. Indeed, as observed in other configurations for monodisperse systems, bidisperse rafts have both a granular and an elastic character: chain forces and collective effects must be taken into account to fully understand our results.
Gravitational Chern-Simons and the adiabatic limit
NASA Astrophysics Data System (ADS)
McLellan, Brendan
2010-12-01
We compute the gravitational Chern-Simons term explicitly for an adiabatic family of metrics using standard methods in general relativity. We use the fact that our base three-manifold is a quasiregular K-contact manifold heavily in this computation. Our key observation is that this geometric assumption corresponds exactly to a Kaluza-Klein Ansatz for the metric tensor on our three-manifold, which allows us to translate our problem into the language of general relativity. Similar computations have been performed by Guralnik et al. [Ann. Phys. 308, 222 (2008)], although not in the adiabatic context.
Speeding up Adiabatic Quantum State Transfer by Using Dressed States
NASA Astrophysics Data System (ADS)
Baksic, Alexandre; Ribeiro, Hugo; Clerk, Aashish A.
2016-06-01
We develop new pulse schemes to significantly speed up adiabatic state transfer protocols. Our general strategy involves adding corrections to an initial control Hamiltonian that harness nonadiabatic transitions. These corrections define a set of dressed states that the system follows exactly during the state transfer. We apply this approach to stimulated Raman adiabatic passage protocols and show that a suitable choice of dressed states allows one to design fast protocols that do not require additional couplings, while simultaneously minimizing the occupancy of the "intermediate" level.
Quantum Adiabatic Pumping by Modulating Tunnel Phase in Quantum Dots
NASA Astrophysics Data System (ADS)
Taguchi, Masahiko; Nakajima, Satoshi; Kubo, Toshihiro; Tokura, Yasuhiro
2016-08-01
In a mesoscopic system, under zero bias voltage, a finite charge is transferred by quantum adiabatic pumping by adiabatically and periodically changing two or more control parameters. We obtained expressions for the pumped charge for a ring of three quantum dots (QDs) by choosing the magnetic flux penetrating the ring as one of the control parameters. We found that the pumped charge shows a steplike behavior with respect to the variance of the flux. The value of the step heights is not universal but depends on the trajectory of the control parameters. We discuss the physical origin of this behavior on the basis of the Fano resonant condition of the ring.
Classical nuclear motion coupled to electronic non-adiabatic transitions
Agostini, Federica; Abedi, Ali; Gross, E. K. U.
2014-12-07
Based on the exact factorization of the electron-nuclear wave function, we have recently proposed a mixed quantum-classical scheme [A. Abedi, F. Agostini, and E. K. U. Gross, Europhys. Lett. 106, 33001 (2014)] to deal with non-adiabatic processes. Here we present a comprehensive description of the formalism, including the full derivation of the equations of motion. Numerical results are presented for a model system for non-adiabatic charge transfer in order to test the performance of the method and to validate the underlying approximations.
Gravitational Chern-Simons and the adiabatic limit
McLellan, Brendan
2010-12-15
We compute the gravitational Chern-Simons term explicitly for an adiabatic family of metrics using standard methods in general relativity. We use the fact that our base three-manifold is a quasiregular K-contact manifold heavily in this computation. Our key observation is that this geometric assumption corresponds exactly to a Kaluza-Klein Ansatz for the metric tensor on our three-manifold, which allows us to translate our problem into the language of general relativity. Similar computations have been performed by Guralnik et al.[Ann. Phys. 308, 222 (2008)], although not in the adiabatic context.
Adiabatic fluctuations from cosmic strings in a contracting universe
Brandenberger, Robert H.; Takahashi, Tomo; Yamaguchi, Masahide E-mail: tomot@cc.saga-u.ac.jp
2009-07-01
We show that adiabatic, super-Hubble, and almost scale invariant density fluctuations are produced by cosmic strings in a contracting universe. An essential point is that isocurvature perturbations produced by topological defects such as cosmic strings on super-Hubble scales lead to a source term which seeds the growth of curvature fluctuations on these scales. Once the symmetry has been restored at high temperatures, the isocurvature seeds disappear, and the fluctuations evolve as adiabatic ones in the expanding phase. Thus, cosmic strings may be resurrected as a mechanism for generating the primordial density fluctuations observed today.
Spatial adiabatic passage: a review of recent progress
NASA Astrophysics Data System (ADS)
Menchon-Enrich, R.; Benseny, A.; Ahufinger, V.; Greentree, A. D.; Busch, Th; Mompart, J.
2016-07-01
Adiabatic techniques are known to allow for engineering quantum states with high fidelity. This requirement is currently of large interest, as applications in quantum information require the preparation and manipulation of quantum states with minimal errors. Here we review recent progress on developing techniques for the preparation of spatial states through adiabatic passage, particularly focusing on three state systems. These techniques can be applied to matter waves in external potentials, such as cold atoms or electrons, and to classical waves in waveguides, such as light or sound.
Adiabatic effects in the dynamics of Langmuir solitons
Astrelin, V.T.; Breizman, B.N.; Sedlacek, Z.; Jungwirth, K.
1988-06-01
The adiabatic slowness with which the plasma density profile is reconstructed from localized in large-amplitude Langmuir solitons is characteristic of such solitons. Several examples making use of this feature in the description of the soliton dynamics are given. Specifically, long-lived states in the form of composite solitons ar found. Additional limitations are found on the interaction of solitons with each other and with sound waves. The effect of the adiabatic nature on the formation of solitons from free plasmons is discussed.
Power-driven and adiabatic expansions into vacuum
NASA Astrophysics Data System (ADS)
Farnsworth, A. V., Jr.
1980-08-01
Analytical solutions are obtained for the planar, cylindrical, and spherical expansions into vacuum of matter initially concentrated at a plane, a line, or a point. Both power-driven and adiabatic expansions are considered, where in the power-driven case, the specific power is deposited uniformly in space, but may vary in time according to a power law. These problems are found to be self-similar. The non-self-similar motion of matter during the adiabatic expansion that follows a power pulse of finite duration has also been addressed and a solution has been obtained.
Adiabatic regularisation of power spectra in k-inflation
Alinea, Allan L.; Kubota, Takahiro; Nakanishi, Yukari; Naylor, Wade E-mail: kubota@celas.osaka-u.ac.jp E-mail: naylor@phys.sci.osaka-u.ac.jp
2015-06-01
We look at the question posed by Parker et al. about the effect of UV regularisation on the power spectrum for inflation. Focusing on the slow-roll k-inflation, we show that up to second order in the Hubble and sound flow parameters, the adiabatic regularisation of such model leads to no difference in the power spectrum apart from certain cases that violate near scale-invariant power spectra. Furthermore, extending to non-minimal k-inflation, we establish the equivalence of the subtraction terms in the adiabatic regularisation of the power spectrum in Jordan and Einstein frames.
Local control of non-adiabatic dissociation dynamics
NASA Astrophysics Data System (ADS)
Bomble, L.; Chenel, A.; Meier, C.; Desouter-Lecomte, M.
2011-05-01
We present a theoretical approach which consists of applying the strategy of local control to projectors based on asymptotic scattering states. This allows to optimize final state distributions upon laser excitation in cases where strong non-adiabatic effects are present. The approach, despite being based on a time-local formulation, can take non-adiabatic transitions that appear at later times fully into account and adopt a corresponding control strategy. As an example, we show various dissociation channels of HeH+, a system where the ultrafast dissociation dynamics is determined by strong non-Born-Oppenheimer effects.
Spatial adiabatic passage: a review of recent progress.
Menchon-Enrich, R; Benseny, A; Ahufinger, V; Greentree, A D; Busch, Th; Mompart, J
2016-07-01
Adiabatic techniques are known to allow for engineering quantum states with high fidelity. This requirement is currently of large interest, as applications in quantum information require the preparation and manipulation of quantum states with minimal errors. Here we review recent progress on developing techniques for the preparation of spatial states through adiabatic passage, particularly focusing on three state systems. These techniques can be applied to matter waves in external potentials, such as cold atoms or electrons, and to classical waves in waveguides, such as light or sound. PMID:27245462
Bulk Properties of Ni3Al(gamma') With Cu and Au Additions
NASA Technical Reports Server (NTRS)
Bozzolo, Guillermo; Ferrante, John
1995-01-01
The BFS method for alloys is applied to the study of 200 alloys obtained from adding Cu and Au impurities to a Ni3Al matrix. We analyze the trends in the bulk properties of these alloys (heat of formation, lattice parameter, and bulk modulus) and detect specific alloy compositions for which these quantities have particular values. A detailed analysis of the atomic interactions that lead to the preferred ordering patterns is presented.
Yuan, Fuping Wu, Xiaolei
2014-12-15
A series of large-scale molecular dynamics simulations were conducted to investigate the scaling laws and the related atomistic deformation mechanisms of Cu monocrystal samples containing randomly placed nanovoids under adiabatic uniaxial strain compression. At onset of yielding, plastic deformation is accommodated by dislocations emitted from void surfaces as shear loops. The collapse of voids are observed by continuous emissions of dislocations from void surfaces and their interactions with further plastic deformation. The simulation results also suggest that the effect modulus, the yield stress and the energy aborption density of samples under uniaxial strain are linearly proportional to the relative density ρ. Moreover, the yield stress, the average flow stress and the energy aborption density of samples with the same relative density show a strong dependence on the void diameter d, expressed by exponential relations with decay coefficients much higher than -1/2. The corresponding atomistic mechanisms for scaling laws of the relative density and the void diameter were also presented. The present results should provide insights for understanding deformation mechanisms of nanoporous metals under extreme conditions.
NASA Astrophysics Data System (ADS)
Kimura, Jun-Ichi; Kawabata, Hiroshi
2014-06-01
numerical mass balance calculation model for the adiabatic melting of a dry to hydrous peridotite has been programmed in order to simulate the trace element compositions of basalts from mid-ocean ridges, back-arc basins, ocean islands, and large igneous provinces. The Excel spreadsheet-based calculator, Hydrous Adiabatic Mantle Melting Simulator version 1 (HAMMS1) uses (1) a thermodynamic model of fractional adiabatic melting of mantle peridotite, with (2) the parameterized experimental melting relationships of primitive to depleted mantle sources in terms of pressure, temperature, water content, and degree of partial melting. The trace element composition of the model basalt is calculated from the accumulated incremental melts within the adiabatic melting regime, with consideration for source depletion. The mineralogic mode in the primitive to depleted source mantle in adiabat is calculated using parameterized experimental results. Partition coefficients of the trace elements of mantle minerals are parameterized to melt temperature mostly from a lattice strain model and are tested using the latest compilations of experimental results. The parameters that control the composition of trace elements in the model are as follows: (1) mantle potential temperature, (2) water content in the source mantle, (3) depth of termination of adiabatic melting, and (4) source mantle depletion. HAMMS1 enables us to obtain the above controlling parameters using Monte Carlo fitting calculations and by comparing the calculated basalt compositions to primary basalt compositions. Additionally, HAMMS1 compares melting parameters with a major element model, which uses petrogenetic grids formulated from experimental results, thus providing better constraints on the source conditions.
Enhanced skin adhesive patch with modulus-tunable composite micropillars.
Bae, Won Gyu; Kim, Doogon; Kwak, Moon Kyu; Ha, Laura; Kang, Seong Min; Suh, Kahp Y
2013-01-01
Modulus-tunable composite micropillars are presented by combining replica molding and selective inking for skin adhesive patch in "ubiquitous"-health diagnostic devices. Inspired from hierarchical hairs in the gecko's toe pad, a simple method is presented to form composite polydimethylsiloxane (PDMS) micropillars that are highly adhesive (∼1.8 N cm(-2) ) and mechanically robust (∼30 cycles).
Multiple-filter approach to phase retrieval from modulus data.
Frieden, B R; Oh, C
1992-03-10
A new approach is given for the problem of reconstruction of phase from modulus data. A set of Wiener-filter functions is formed that multiply, in turn, displaced versions of the modulus data (in frequency space) such that the sum is a minimum L(2)-error norm solution for the object. The modulus data are permitted to contain both noise and signal (object) components. The required statistics are power spectra of the signal and noise, and correlations between modulus data at given frequencies and complex object spectral values at adjacent frequencies. In a numerical simulation, a 3 x 3 filter array is used to reconstruct any member of an object class consisting of 16 pictures of space shuttles in various combinations. The 16 pictures are used as a learning set to form the required power spectra and correlations mentioned above. Reconstructions are formed in the presence of data noise, data gaps, and filter-construction noise, in varying amounts. Results are encouraging in that the space shuttle images are always recognizable.
NASA Astrophysics Data System (ADS)
Yuan, Wen-Xiang
2012-03-01
The frequency dependence of electric modulus of polycrystalline CaCu3Ti4O12 (CCTO) ceramics has been investigated. The experimental data have also been analyzed in the complex plane of impedance and electric modulus, and a suitable equivalent circuit has been proposed to explain the dielectric response. Four dielectric responses are first distinguished in the impedance and modulus spectroscopies. The results are well interpreted in terms of a triple insulating barrier capacitor model. Using this model, these four dielectric relaxations are attributed to the domain, domain-boundary, grain-boundary, and surface layer effects with three Maxwell-Wagner relaxations. Moreover, the values of the resistance and capacitance of bulk CCTO phase, domain-boundary, grain-boundary and surface layer contributions have been calculated directly from the peak characteristics of spectroscopic plots.
High elastic modulus nanopowder reinforced resin composites for dental applications
NASA Astrophysics Data System (ADS)
Wang, Yijun
2007-12-01
Dental restorations account for more than $3 billion dollars a year on the market. Among them, all-ceramic dental crowns draw more and more attention and their popularity has risen because of their superior aesthetics and biocompatibility. However, their relatively high failure rate and labor-intensive fabrication procedure still limit their application. In this thesis, a new family of high elastic modulus nanopowder reinforced resin composites and their mechanical properties are studied. Materials with higher elastic modulus, such as alumina and diamond, are used to replace the routine filler material, silica, in dental resin composites to achieve the desired properties. This class of composites is developed to serve (1) as a high stiffness support to all-ceramic crowns and (2) as a means of joining independently fabricated crown core and veneer layers. Most of the work focuses on nano-sized Al2O3 (average particle size 47 nm) reinforcement in a polymeric matrix with 50:50 Bisphenol A glycidyl methacrylate (Bis-GMA): triethylene glycol dimethacrylate (TEGDMA) monomers. Surfactants, silanizing agents and primers are examined to obtain higher filler levels and enhance the bonding between filler and matrix. Silane agents work best. The elastic modulus of a 57.5 vol% alumina/resin composite is 31.5 GPa compared to current commercial resin composites with elastic modulus <15 GPa. Chemical additives can also effectively raise the hardness to as much as 1.34 GPa. Besides>alumina, diamond/resin composites are studied. An elastic modulus of about 45 GPa is obtained for a 57 vol% diamond/resin composite. Our results indicate that with a generally monodispersed nano-sized high modulus filler, relatively high elastic modulus resin-based composite cements are possible. Time-dependent behavior of our resin composites is also investigated. This is valuable for understanding the behavior of our material and possible fatigue testing in the future. Our results indicate that with
Does temperature increase or decrease in adiabatic decompression of magma?
NASA Astrophysics Data System (ADS)
Kilinc, A. I.; Ghiorso, M. S.; Khan, T.
2011-12-01
We have modeled adiabatic decompression of an andesitic and a basaltic magma as an isentropic process using the Melts algorithm. Our modeling shows that during adiabatic decompression temperature of andesitic magma increases but temperature of basaltic magma decreases. In an isentropic process entropy is constant so change of temperature with pressure can be written as dT/dP=T (dV/dT)/Cp where T (dV/dT)/Cp is generally positive. If delta P is negative so is delta T. In general, in the absence of phase change, we expect the temperature to decrease with adiabatic decompression. The effect of crystallization is to turn a more entropic phase (liquid) into a less entropic phase (solid), which must be compensated by raising the temperature. If during adiabatic decompression there is small amount or no crystallization, T (dV/dT)/Cp effect which lowers the temperature overwhelms the small amount of crystallization, which raises the temperature, and overall system temperature decreases.
On adiabatic stabilization and geometry of Bunsen flames
Sun, C.J.; Sung, C.J.; Law, C.K.
1994-12-31
Two aspects of stretched flame dynamics are investigated via the model problem of the stabilization and geometry of Bunsen flames. Specifically, the possibility of stabilizing a Bunsen flame without heat loss to the burner rim is experimentally investigated by examining the temperature of the rim, the temperature gradient between the rim and the flame base, and the standoff distance of the flame base in relation to the flame thickness. Results show that, while heat loss is still the dominant stabilization mechanism for flames in uniform flows and for strong flames in parabolic flow, adiabatic stabilization and, subsequently, blowoff are indeed possible for weak flames in parabolic flows. The adiabatically stabilized flame is then modeled by using the scalar field formulation and by allowing for the effects of curvature and aerodynamic straining on the local flame speed. The calculated flame configuration agrees well with the experiment for the adiabatically stabilized flame but not for the nonadiabatic flame. Results further show that active modification of the flame curvature is the dominant cause for the flame to maintain adiabatic stabilization. Implications of the present results on turbulent flame modeling are discussed.
Digitized adiabatic quantum computing with a superconducting circuit
NASA Astrophysics Data System (ADS)
Barends, R.; Shabani, A.; Lamata, L.; Kelly, J.; Mezzacapo, A.; Heras, U. Las; Babbush, R.; Fowler, A. G.; Campbell, B.; Chen, Yu; Chen, Z.; Chiaro, B.; Dunsworth, A.; Jeffrey, E.; Lucero, E.; Megrant, A.; Mutus, J. Y.; Neeley, M.; Neill, C.; O'Malley, P. J. J.; Quintana, C.; Roushan, P.; Sank, D.; Vainsencher, A.; Wenner, J.; White, T. C.; Solano, E.; Neven, H.; Martinis, John M.
2016-06-01
Quantum mechanics can help to solve complex problems in physics and chemistry, provided they can be programmed in a physical device. In adiabatic quantum computing, a system is slowly evolved from the ground state of a simple initial Hamiltonian to a final Hamiltonian that encodes a computational problem. The appeal of this approach lies in the combination of simplicity and generality; in principle, any problem can be encoded. In practice, applications are restricted by limited connectivity, available interactions and noise. A complementary approach is digital quantum computing, which enables the construction of arbitrary interactions and is compatible with error correction, but uses quantum circuit algorithms that are problem-specific. Here we combine the advantages of both approaches by implementing digitized adiabatic quantum computing in a superconducting system. We tomographically probe the system during the digitized evolution and explore the scaling of errors with system size. We then let the full system find the solution to random instances of the one-dimensional Ising problem as well as problem Hamiltonians that involve more complex interactions. This digital quantum simulation of the adiabatic algorithm consists of up to nine qubits and up to 1,000 quantum logic gates. The demonstration of digitized adiabatic quantum computing in the solid state opens a path to synthesizing long-range correlations and solving complex computational problems. When combined with fault-tolerance, our approach becomes a general-purpose algorithm that is scalable.
Digitized adiabatic quantum computing with a superconducting circuit.
Barends, R; Shabani, A; Lamata, L; Kelly, J; Mezzacapo, A; Las Heras, U; Babbush, R; Fowler, A G; Campbell, B; Chen, Yu; Chen, Z; Chiaro, B; Dunsworth, A; Jeffrey, E; Lucero, E; Megrant, A; Mutus, J Y; Neeley, M; Neill, C; O'Malley, P J J; Quintana, C; Roushan, P; Sank, D; Vainsencher, A; Wenner, J; White, T C; Solano, E; Neven, H; Martinis, John M
2016-06-01
Quantum mechanics can help to solve complex problems in physics and chemistry, provided they can be programmed in a physical device. In adiabatic quantum computing, a system is slowly evolved from the ground state of a simple initial Hamiltonian to a final Hamiltonian that encodes a computational problem. The appeal of this approach lies in the combination of simplicity and generality; in principle, any problem can be encoded. In practice, applications are restricted by limited connectivity, available interactions and noise. A complementary approach is digital quantum computing, which enables the construction of arbitrary interactions and is compatible with error correction, but uses quantum circuit algorithms that are problem-specific. Here we combine the advantages of both approaches by implementing digitized adiabatic quantum computing in a superconducting system. We tomographically probe the system during the digitized evolution and explore the scaling of errors with system size. We then let the full system find the solution to random instances of the one-dimensional Ising problem as well as problem Hamiltonians that involve more complex interactions. This digital quantum simulation of the adiabatic algorithm consists of up to nine qubits and up to 1,000 quantum logic gates. The demonstration of digitized adiabatic quantum computing in the solid state opens a path to synthesizing long-range correlations and solving complex computational problems. When combined with fault-tolerance, our approach becomes a general-purpose algorithm that is scalable. PMID:27279216
Digitized adiabatic quantum computing with a superconducting circuit.
Barends, R; Shabani, A; Lamata, L; Kelly, J; Mezzacapo, A; Las Heras, U; Babbush, R; Fowler, A G; Campbell, B; Chen, Yu; Chen, Z; Chiaro, B; Dunsworth, A; Jeffrey, E; Lucero, E; Megrant, A; Mutus, J Y; Neeley, M; Neill, C; O'Malley, P J J; Quintana, C; Roushan, P; Sank, D; Vainsencher, A; Wenner, J; White, T C; Solano, E; Neven, H; Martinis, John M
2016-06-08
Quantum mechanics can help to solve complex problems in physics and chemistry, provided they can be programmed in a physical device. In adiabatic quantum computing, a system is slowly evolved from the ground state of a simple initial Hamiltonian to a final Hamiltonian that encodes a computational problem. The appeal of this approach lies in the combination of simplicity and generality; in principle, any problem can be encoded. In practice, applications are restricted by limited connectivity, available interactions and noise. A complementary approach is digital quantum computing, which enables the construction of arbitrary interactions and is compatible with error correction, but uses quantum circuit algorithms that are problem-specific. Here we combine the advantages of both approaches by implementing digitized adiabatic quantum computing in a superconducting system. We tomographically probe the system during the digitized evolution and explore the scaling of errors with system size. We then let the full system find the solution to random instances of the one-dimensional Ising problem as well as problem Hamiltonians that involve more complex interactions. This digital quantum simulation of the adiabatic algorithm consists of up to nine qubits and up to 1,000 quantum logic gates. The demonstration of digitized adiabatic quantum computing in the solid state opens a path to synthesizing long-range correlations and solving complex computational problems. When combined with fault-tolerance, our approach becomes a general-purpose algorithm that is scalable.
Failure of geometric electromagnetism in the adiabatic vector Kepler problem
Anglin, J.R.; Schmiedmayer, J.
2004-02-01
The magnetic moment of a particle orbiting a straight current-carrying wire may precess rapidly enough in the wire's magnetic field to justify an adiabatic approximation, eliminating the rapid time dependence of the magnetic moment and leaving only the particle position as a slow degree of freedom. To zeroth order in the adiabatic expansion, the orbits of the particle in the plane perpendicular to the wire are Keplerian ellipses. Higher-order postadiabatic corrections make the orbits precess, but recent analysis of this 'vector Kepler problem' has shown that the effective Hamiltonian incorporating a postadiabatic scalar potential ('geometric electromagnetism') fails to predict the precession correctly, while a heuristic alternative succeeds. In this paper we resolve the apparent failure of the postadiabatic approximation, by pointing out that the correct second-order analysis produces a third Hamiltonian, in which geometric electromagnetism is supplemented by a tensor potential. The heuristic Hamiltonian of Schmiedmayer and Scrinzi is then shown to be a canonical transformation of the correct adiabatic Hamiltonian, to second order. The transformation has the important advantage of removing a 1/r{sup 3} singularity which is an artifact of the adiabatic approximation.
Fast Quasi-Adiabatic Gas Cooling: An Experiment Revisited
ERIC Educational Resources Information Center
Oss, S.; Gratton, L. M.; Calza, G.; Lopez-Arias, T.
2012-01-01
The well-known experiment of the rapid expansion and cooling of the air contained in a bottle is performed with a rapidly responsive, yet very cheap thermometer. The adiabatic, low temperature limit is approached quite closely and measured with our apparatus. A straightforward theoretical model for this process is also presented and discussed.…
Quantum back-reaction from non-adiabatic changes
NASA Astrophysics Data System (ADS)
Asplund, Curtis; Berenstein, David
2011-04-01
Motivated by the problem of thermalization in QFTs and the dual non-equilibrium BH dynamics, we examine a generic and non-trivial aspect of these phenomena, non-adiabatic changes, in a highly simplified setting. We consider a harmonic oscillator whose frequency depends on a second quantum variable x. Beginning with a classical analysis, we show how the system can be described by an improved adiabatic expansion with a velocity dependent force for x. We find an instability at a critical velocity beyond which the adiabatic (Born-Oppenheimer) approximation breaks down. We extend this calculation to the fully quantum system and to field theory and describe how to study fermions with similar techniques. Finally, we set up a model with an abrupt change in the oscillator whose quantum mechanics can be solved exactly so that one can study the effects of back-reaction of a fully non-adiabatic change in a controlled setting. We comment on applications of these general results to the physics of D-branes, inflation, and BHs in AdS/CFT.
Adiabatic quantum computing with phase modulated laser pulses
Goswami, Debabrata
2005-01-01
Implementation of quantum logical gates for multilevel systems is demonstrated through decoherence control under the quantum adiabatic method using simple phase modulated laser pulses. We make use of selective population inversion and Hamiltonian evolution with time to achieve such goals robustly instead of the standard unitary transformation language. PMID:17195865
The flat Grothendieck-Riemann-Roch theorem without adiabatic techniques
NASA Astrophysics Data System (ADS)
Ho, Man-Ho
2016-09-01
In this paper we give a simplified proof of the flat Grothendieck-Riemann-Roch theorem. The proof makes use of the local family index theorem and basic computations of the Chern-Simons form. In particular, it does not involve any adiabatic limit computation of the reduced eta-invariant.
When an Adiabatic Irreversible Expansion or Compression Becomes Reversible
ERIC Educational Resources Information Center
Anacleto, Joaquim; Ferreira, J. M.; Soares, A. A.
2009-01-01
This paper aims to contribute to a better understanding of the concepts of a "reversible process" and "entropy". For this purpose, an adiabatic irreversible expansion or compression is analysed, by considering that an ideal gas is expanded (compressed), from an initial pressure P[subscript i] to a final pressure P[subscript f], by being placed in…
A Kinetic Study of the Adiabatic Polymerization of Acrylamide.
ERIC Educational Resources Information Center
Thomson, R. A. M.
1986-01-01
Discusses theory, procedures, and results for an experiment which demonstrates the application of basic physics to chemical problems. The experiment involves the adiabatic process, in which polymerization carried out in a vacuum flask is compared to the theoretical prediction of the model with the temperature-time curve obtained in practice. (JN)
Properties of Bulk Sintered Silver As a Function of Porosity
Wereszczak, Andrew A; Vuono, Daniel J; Wang, Hsin; Ferber, Mattison K; Liang, Zhenxian
2012-06-01
This report summarizes a study where various properties of bulk-sintered silver were investigated over a range of porosity. This work was conducted within the National Transportation Research Center's Power Device Packaging project that is part of the DOE Vehicle Technologies Advanced Power Electronics and Electric Motors Program. Sintered silver, as an interconnect material in power electronics, inherently has porosity in its produced structure because of the way it is made. Therefore, interest existed in this study to examine if that porosity affected electrical properties, thermal properties, and mechanical properties because any dependencies could affect the intended function (e.g., thermal transfer, mechanical stress relief, etc.) or reliability of that interconnect layer and alter how its performance is modeled. Disks of bulk-sintered silver were fabricated using different starting silver pastes and different sintering conditions to promote different amounts of porosity. Test coupons were harvested out of the disks to measure electrical resistivity and electrical conductivity, thermal conductivity, coefficient of thermal expansion, elastic modulus, Poisson's ratio, and yield stress. The authors fully recognize that the microstructure of processed bulk silver coupons may indeed not be identical to the microstructure produced in thin (20-50 microns) layers of sintered silver. However, measuring these same properties with such a thin actual structure is very difficult, requires very specialized specimen preparation and unique testing instrumentation, is expensive, and has experimental shortfalls of its own, so the authors concluded that the herein measured responses using processed bulk sintered silver coupons would be sufficient to determine acceptable values of those properties. Almost all the investigated properties of bulk sintered silver changed with porosity content within a range of 3-38% porosity. Electrical resistivity, electrical conductivity, thermal
Evaluation of Exothermic Reactions from Bulk-Vitrification Melter Feeds Containing Cellulose
Scheele, Randall D.; McNamara, Bruce K.; Bagaasen, Larry M.; Bos, Stanley J.; Kozelisky, Anne E.; Berry, Pam
2007-06-25
PNNL has demonstrated that cellulose effectively reduces the amount of molten ionic salt during Bulk Vitrification of simulated Hanford Low Level Waste (LLW). To address concerns about the potential reactivity of cellulose-LLW, PNNL used thermogravimetric analysis, differential thermal analysis, and accelerating rate calorimetry to determine in these preliminary studies that these mixtures will support a self-sustaining reaction if heated to 110°C at adiabatic conditions. Additional testing is recommended.
Dai, Sheng; Zhao, Jiong; He, Mo-rigen; Wang, Xiaoguang; Wan, Jingchun; Shan, Zhiwei; Zhu, Jing
2015-01-14
The elastic properties of gallium nitride (GaN) nanowires with different structures were investigated by in situ electron microscopy in this work. The electric-field-induced resonance method was utilized to reveal that the single crystalline GaN nanowires, along [120] direction, had the similar Young's modulus as the bulk value at the diameter ranging 92-110 nm. Meanwhile, the elastic behavior of the obtuse-angle twin (OT) GaN nanowires was disclosed both by the in situ SEM resonance technique and in situ transmission electron microscopy tensile test for the first time. Our results showed that the average Young's modulus of these OT nanowires was greatly decreased to about 66 GPa and indicated no size dependence at the diameter ranging 98-171 nm. A quantitative explanation for this phenomenon is proposed based on the rules of mixtures in classical mechanics. It is revealed that the elastic modulus of one-dimensional nanomaterials is dependent on the relative orientations and the volume fractions of the planar defects.
High modulus invert analog glass compositions containing beryllia
NASA Technical Reports Server (NTRS)
Bacon, J. F. (Inventor)
1974-01-01
Glass compositions having a Young's modulus of at least 15 million psi and a specific modulus of at least 110 million inches consisting essentially of, in mols, 10-45% SiO2, 2-15% Li2O, 3-34% BeO, 12-36% of at least one bivalent oxide selected from the group consisting of CaO, ZnO, MgO and CuO, 10-39% of at least one trivalent oxide selected from the group consisting of Al2O3, B2O3, La2O3, Y2O3 and the mixed rare earth oxides, the total number of said bivalent and trivalent oxides being at least three, and up to 10% of a tetravalent oxide selected from the group consisting of ZrO2, TiO2 and CeO2.
Determination of Modulus of Metal Films Using Thermoreflectance
NASA Astrophysics Data System (ADS)
Jagannadham, K.
2015-01-01
The acoustic displacements in a film of indium pressed on to a sapphire wafer were generated by incidence of a Q-switched Nd-YAG laser beam. Acoustic displacements from tungsten film deposited on silicon substrate were also measured by the same technique. Thermoreflectance from a continuous red laser incident on the surface was used simultaneously to measure the acoustic oscillations. The acoustic oscillations were simulated using the solution to the modified wave equation. The acoustic velocity and the modulus of the metal film were determined from the simulation of the experimental results. It is shown that this technique provides a nondestructive method of determination of acoustic velocity and modulus in the metal films.
Modified constant modulus algorithm for polarization-switched QPSK.
Johannisson, Pontus; Sjödin, Martin; Karlsson, Magnus; Wymeersch, Henk; Agrell, Erik; Andrekson, Peter A
2011-04-11
By using a generalized cost function, a modified constant modulus algorithm (CMA) that allows polarization demultiplexing and equalization of polarization-switched QPSK is found. An implementation that allows easy switching between the conventional and the modified CMA is described. Using numerical simulations, the suggested algorithm is shown to have similar performance for polarization-switched QPSK as CMA has for polarization-multiplexed QPSK.
Elastohydrodynamics of elliptical contacts for materials of low elastic modulus
NASA Technical Reports Server (NTRS)
Hamrock, B. J.; Dowson, D.
1983-01-01
The influence of the ellipticity parameter k and the dimensionless speed U, load W, and materials G parameters on minimum film thickness for materials of low elastic modulus was investigated. The ellipticity parameter was varied from 1 (a ball-on-plane configuration) to 12 (a configuration approaching a line contact); U and W were each varied by one order of magnitude. Seventeen cases were used to generate the minimum- and central-film-thickness relations. The influence of lubricant starvation on minimum film thickness in starved elliptical, elastohydrodynamic configurations was also investigated for materials of low elastic modulus. Lubricant starvation was studied simply by moving the inlet boundary closer to the center of the conjunction in the numerical solutions. Contour plots of pressure and film thickness in and around the contact were presented for both fully flooded and starved lubrication conditions. It is evident from these figures that the inlet pressure contours become less circular and closer to the edge of the Hertzian contact zone and that the film thickness decreases substantially as the serverity of starvation increases. The results presented reveal the essential features of both fully flooded and starved, elliptical, elastohydrodynamic conjunctions for materials of low elastic modulus.
Ultra-high modulus organic fiber hybrid composites
NASA Technical Reports Server (NTRS)
Champion, A. R.
1981-01-01
An experimental organic fiber, designated Fiber D, was characterized, and its performance as a reinforcement for composites was investigated. The fiber has a modulus of 172 GPa, tensile strength of 3.14 GPa, and density of 1.46 gm/cu cm. Unidirectional Fiber D/epoxy laminates containing 60 percent fiber by volume were evaluated in flexure, shear, and compression, at room temperature and 121 C in both the as fabricated condition and after humidity aging for 14 days at 95 percent RH and 82 C. A modulus of 94.1 GPa, flexure strength of 700 MPa, shear strength of 54 MPa, and compressive strength of 232 MPa were observed at room temperature. The as-fabricated composites at elevated temperature and humidity aged material at room temperature had properties 1 to 20 percent below these values. Combined humidity aging plus evaluated temperature testing resulted in even lower mechanical properties. Hybrid composite laminates of Fiber D with Fiber FP alumina or Thornel 300 graphite fiber were also evaluated and significant increases in modulus, flexure, and compressive strengths were observed.
Elastic modulus of tree frog adhesive toe pads.
Barnes, W Jon P; Goodwyn, Pablo J Perez; Nokhbatolfoghahai, Mohsen; Gorb, Stanislav N
2011-10-01
Previous work using an atomic force microscope in nanoindenter mode indicated that the outer, 10- to 15-μm thick, keratinised layer of tree frog toe pads has a modulus of elasticity equivalent to silicone rubber (5-15 MPa) (Scholz et al. 2009), but gave no information on the physical properties of deeper structures. In this study, micro-indentation is used to measure the stiffness of whole toe pads of the tree frog, Litoria caerulea. We show here that tree frog toe pads are amongst the softest of biological structures (effective elastic modulus 4-25 kPa), and that they exhibit a gradient of stiffness, being stiffest on the outside. This stiffness gradient results from the presence of a dense network of capillaries lying beneath the pad epidermis, which probably has a shock absorbing function. Additionally, we compare the physical properties (elastic modulus, work of adhesion, pull-off force) of the toe pads of immature and adult frogs. PMID:21667266
Coefficient of thermal expansion and elastic modulus of thin films
NASA Astrophysics Data System (ADS)
de Lima, M. M.; Lacerda, R. G.; Vilcarromero, J.; Marques, F. C.
1999-11-01
The coefficient of thermal expansion (CTE), biaxial modulus, and stress of some amorphous semiconductors (a-Si:H, a-C:H, a-Ge:H, and a-GeCx:H) and metallic (Ag and Al) thin films were studied. The thermal expansion and the biaxial modulus were measured by the thermally induced bending technique. The stress of the metallic films, deposited by thermal evaporation (Ag and Al), is tensile, while that of the amorphous films deposited by sputtering (a-Si:H, a-Ge:H, and a-GeCx:H) and by glow discharge (a-C:H) is compressive. We observed that the coefficient of thermal expansion of the tetrahedral amorphous thin films prepared in this work, as well as that of the films reported in literature, depend on the network strain. The CTE of tensile films is smaller than that of their corresponding crystalline semiconductors, but it is higher for compressive films. On the other hand, we found out that the elastic biaxial modulus of the amorphous and metallic films is systematically smaller than that of their crystalline counterparts. This behavior stands for other films reported in the literature that were prepared by different techniques and deposition conditions. These differences were attributed to the reduction of the coordination number and to the presence of defects, such as voids and dangling bonds, in amorphous films. On the other hand, columnar structure and microcrystallinity account for the reduced elasticity of the metallic films.
Measurement of Elastic Modulus of Collagen Type I Single Fiber.
Dutov, Pavel; Antipova, Olga; Varma, Sameer; Orgel, Joseph P R O; Schieber, Jay D
2016-01-01
Collagen fibers are the main components of the extra cellular matrix and the primary contributors to the mechanical properties of tissues. Here we report a novel approach to measure the longitudinal component of the elastic moduli of biological fibers under conditions close to those found in vivo and apply it to type I collagen from rat tail tendon. This approach combines optical tweezers, atomic force microscopy, and exploits Euler-Bernoulli elasticity theory for data analysis. This approach also avoids drying for measurements or visualization, since samples are freshly extracted. Importantly, strains are kept below 0.5%, which appear consistent with the linear elastic regime. We find, surprisingly, that the longitudinal elastic modulus of type I collagen cannot be represented by a single quantity but rather is a distribution that is broader than the uncertainty of our experimental technique. The longitudinal component of the single-fiber elastic modulus is between 100 MPa and 360 MPa for samples extracted from different rats and/or different parts of a single tail. Variations are also observed in the fibril-bundle/fibril diameter with an average of 325±40 nm. Since bending forces depend on the diameter to the fourth power, this variation in diameter is important for estimating the range of elastic moduli. The remaining variations in the modulus may be due to differences in composition of the fibril-bundles, or the extent of the proteoglycans constituting fibril-bundles, or that some single fibrils may be of fibril-bundle size.
Compressive elastic modulus of natural fiber based binary composites
NASA Astrophysics Data System (ADS)
Widayani, Susanah, Y.; Utami, L. S.; Khotimah, S. N.; Viridi, S.
2012-06-01
The composites made of bamboo apus fiber - epoxy resin and charcoal - tapioca starch with several compositions have been synthesized. Bamboo fiber powder as the rest of cutting process was refined and filtered by mesh 40 before used. Epoxy resin 1021A and hardener 1021B has been used as resin. The synthesis of epoxy resin-based composites was carried out via simple mixing method by adding adequate 70% ethanol solution before drying. The 100 mesh-filtered dry charcoal was mixed with tapioca mixture before it was pressed and dried to produce briquette composites. To study the compressive elastic modulus of the composites, pressure tests using Mark 10 Pressure Test Machine have been carried out. It was found that all the composites show maximum compressive elastic modulus at certain component compositions. The maximum elastic modulus for bamboo fiber-epoxy resin, charcoal - epoxy resin and charcoal-tapioca starch were observed at 52.9%, 56.3%, and 25.0% of mass fraction of bamboo fiber, charcoal and tapioca starch, respectively.
Young's modulus and hardness of shark tooth biomaterials.
Whitenack, Lisa B; Simkins, Daniel C; Motta, Philip J; Hirai, Makoto; Kumar, Ashok
2010-03-01
To date, the majority of studies on feeding mechanics in sharks have focused on the movement of cranial components and muscle function, with little attention to tooth properties or function. Attributes related to mechanical properties, such as structural strength, may also be subjected to natural selection. Additionally it is necessary to characterize these properties in order to construct biomechanical models of tooth function. The goal of this study was to determine hardness and elastic modulus for the shark tooth materials enameloid, osteodentine, and orthodentine. Five teeth each from one carcharhiniform species, the bonnethead Sphyrna tiburo, and one lamniform, the sand tiger shark Carcharias taurus, were utilized for nanoindentation testing. Each tooth was sectioned transversely, air-dried, and polished. Both enameloid and dentine were tested on each tooth via a Berkovich diamond tip, with nine 2 microm deep indentations per material. t-Tests were used to determine if there were differences in hardness and Young's modulus between the tooth materials of the two species. There was no significant difference between the two species for the material properties of enameloid, however both hardness and Young's modulus were higher for osteodentine than for orthodentine. This may be due to differences in microanatomy and chemical composition, however this needs to be studied in greater detail.
Theory of laser-induced adiabat shaping in inertial fusion implosions: The relaxation method
Betti, R.; Anderson, K.; Knauer, J.; Collins, T.J.B.; McCrory, R.L.; McKenty, P.W.; Skupsky, S.
2005-04-15
The theory of the adiabat shaping induced by a strong shock propagating through a relaxed density profile is carried out for inertial confinement fusion (ICF) capsules. The relaxed profile is produced through a laser prepulse, while the adiabat-shaping shock is driven by the foot of the main laser pulse. The theoretical adiabat profiles accurately reproduce the simulation results. ICF capsules with a shaped adiabat are expected to benefit from improved hydrodynamic stability while maintaining the same one-dimensional performances as flat-adiabat shells.
NASA Astrophysics Data System (ADS)
Duarte, N.; Xiong, Qihua; Srinivas, Tadigadapa; Eklund, Peter
2006-03-01
In this approach, a nanowire beam is fixed at two ends and an AFM is used to apply a force F(x) where x locates the position along the beam and the beam deflection δz(x) is measured simultaneously. This situation is realized by placing a nanobeam over a trench fabricated on a Silicon substrate via photolithography followed by metal evaporation, lift-off and XeF2 etching. The AFM tip force-distance curve is first obtained from experiments on the rigid substrate. The slope of the AFM force-distance obtained when the tip contacts the beam is then measured and the Young's modulus Y is obtained from the change in slope using the Euler-Bernoulli (E-B) equation. The beam dimensions are also required: the beam height and length via AFM and the beam width and length by SEM. We believe this method can be used in any other nano-beam systems to measure the Young's modulus. Results for rectangular ZnS beams (˜100nm x 100 nm x 5μm long) will be presented that demonstrate the potential for this method. Values for Y lower than reported for the bulk are obtained (i.e. Y(nano) ˜ 70% Y(bulk)). This work was supported, in part, by NSF-NIRT DMR-0304178
Robust quantum logic in neutral atoms via adiabatic Rydberg dressing
NASA Astrophysics Data System (ADS)
Keating, Tyler; Cook, Robert L.; Hankin, Aaron M.; Jau, Yuan-Yu; Biedermann, Grant W.; Deutsch, Ivan H.
2015-01-01
We study a scheme for implementing a controlled-Z (cz) gate between two neutral-atom qubits based on the Rydberg blockade mechanism in a manner that is robust to errors caused by atomic motion. By employing adiabatic dressing of the ground electronic state, we can protect the gate from decoherence due to random phase errors that typically arise because of atomic thermal motion. In addition, the adiabatic protocol allows for a Doppler-free configuration that involves counterpropagating lasers in a σ+/σ- orthogonal polarization geometry that further reduces motional errors due to Doppler shifts. The residual motional error is dominated by dipole-dipole forces acting on doubly excited Rydberg atoms when the blockade is imperfect. For reasonable parameters, with qubits encoded into the clock states of 133Cs, we predict that our protocol could produce a cz gate in <10 μ s with error probability on the order of 10-3.
Adiabatic molecular-dynamics-simulation-method studies of kinetic friction
NASA Astrophysics Data System (ADS)
Zhang, J.; Sokoloff, J. B.
2005-06-01
An adiabatic molecular-dynamics method is developed and used to study the Muser-Robbins model for dry friction (i.e., nonzero kinetic friction in the slow sliding speed limit). In this model, dry friction between two crystalline surfaces rotated with respect to each other is due to mobile molecules (i.e., dirt particles) adsorbed at the interface. Our adiabatic method allows us to quickly locate interface potential-well minima, which become unstable during sliding of the surfaces. Since dissipation due to friction in the slow sliding speed limit results from mobile molecules dropping out of such unstable wells, our method provides a way to calculate dry friction, which agrees extremely well with results found by conventional molecular dynamics for the same system, but our method is more than a factor of 10 faster.
Adiabatic far-field sub-diffraction imaging
Cang, Hu; Salandrino, Alessandro; Wang, Yuan; Zhang, Xiang
2015-01-01
The limited resolution of a conventional optical imaging system stems from the fact that the fine feature information of an object is carried by evanescent waves, which exponentially decays in space and thus cannot reach the imaging plane. We introduce here an adiabatic lens, which utilizes a geometrically conformal surface to mediate the interference of slowly decompressed electromagnetic waves at far field to form images. The decompression is satisfying an adiabatic condition, and by bridging the gap between far field and near field, it allows far-field optical systems to project an image of the near-field features directly. Using these designs, we demonstrated the magnification can be up to 20 times and it is possible to achieve sub-50 nm imaging resolution in visible. Our approach provides a means to extend the domain of geometrical optics to a deep sub-wavelength scale. PMID:26258769
Adiabatic creation of atomic squeezing in dark states versus decoherences
Gong, Z. R.; Sun, C. P.; Wang Xiaoguang
2010-07-15
We study the multipartite correlations of the multiatom dark states, which are characterized by the atomic squeezing beyond the pairwise entanglement. It is shown that, in the photon storage process with atomic ensemble via the electromagnetically induced transparency (EIT) mechanism, the atomic squeezing and the pairwise entanglement can be created by adiabatically manipulating the Rabi frequency of the classical light field on the atomic ensemble. We also consider the sudden death for the atomic squeezing and the pairwise entanglement under various decoherence channels. An optimal time for generating the greatest atomic squeezing and pairwise entanglement is obtained by studying in detail the competition between the adiabatic creation of quantum correlation in the atomic ensemble and the decoherence that we describe with three typical decoherence channels.
Adiabatic theory of solitons fed by dispersive waves
NASA Astrophysics Data System (ADS)
Pickartz, Sabrina; Bandelow, Uwe; Amiranashvili, Shalva
2016-09-01
We consider scattering of low-amplitude dispersive waves at an intense optical soliton which constitutes a nonlinear perturbation of the refractive index. Specifically, we consider a single-mode optical fiber and a group velocity matched pair: an optical soliton and a nearly perfectly reflected dispersive wave, a fiber-optical analog of the event horizon. By combining (i) an adiabatic approach that is used in soliton perturbation theory and (ii) scattering theory from quantum mechanics, we give a quantitative account of the evolution of all soliton parameters. In particular, we quantify the increase in the soliton peak power that may result in the spontaneous appearance of an extremely large, so-called champion soliton. The presented adiabatic theory agrees well with the numerical solutions of the pulse propagation equation. Moreover, we predict the full frequency band of the scattered dispersive waves and explain an emerging caustic structure in the space-time domain.
On the Effect of Strain Gradient on Adiabatic Shear Banding
NASA Astrophysics Data System (ADS)
Tsagrakis, Ioannis; Aifantis, Elias C.
2015-10-01
Most of the work on adiabatic shear banding is based on the effect of temperature gradients on shear band nucleation and evolution. In contrast, the present work considers the coupling between temperature and strain gradients. The competition of thermal and strain gradient terms on the onset of instability and its dependence on specimen size is illustrated. It is shown that heat conduction promotes the instability initiation in the hardening part of the homogeneous stress-strain, while the strain gradient term favors the occurrence of this initiation in the softening regime. This behavior is size dependent, i.e., small specimens can support stable homogeneous deformations even in the softening regime. The spacing of adiabatic shear bands is also evaluated by considering the dominant instability mode during the primary stages of the localization process and it is found that it is an increasing function of the strain gradient coefficient.
Steam bottoming cycle for an adiabatic diesel engine
NASA Technical Reports Server (NTRS)
Poulin, E.; Demier, R.; Krepchin, I.; Walker, D.
1984-01-01
Steam bottoming cycles using adiabatic diesel engine exhaust heat which projected substantial performance and economic benefits for long haul trucks were studied. Steam cycle and system component variables, system cost, size and performance were analyzed. An 811 K/6.90 MPa state of the art reciprocating expander steam system with a monotube boiler and radiator core condenser was selected for preliminary design. The costs of the diesel with bottoming system (TC/B) and a NASA specified turbocompound adiabatic diesel with aftercooling with the same total output were compared, the annual fuel savings less the added maintenance cost was determined to cover the increase initial cost of the TC/B system in a payback period of 2.3 years. Steam bottoming system freeze protection strategies were developed, technological advances required for improved system reliability are considered and the cost and performance of advanced systes are evaluated.
Fluctuations of work in nearly adiabatically driven open quantum systems.
Suomela, S; Salmilehto, J; Savenko, I G; Ala-Nissila, T; Möttönen, M
2015-02-01
We extend the quantum jump method to nearly adiabatically driven open quantum systems in a way that allows for an accurate account of the external driving in the system-environment interaction. Using this framework, we construct the corresponding trajectory-dependent work performed on the system and derive the integral fluctuation theorem and the Jarzynski equality for nearly adiabatic driving. We show that such identities hold as long as the stochastic dynamics and work variable are consistently defined. We numerically study the emerging work statistics for a two-level quantum system and find that the conventional diabatic approximation is unable to capture some prominent features arising from driving, such as the continuity of the probability density of work. Our results reveal the necessity of using accurate expressions for the drive-dressed heat exchange in future experiments probing jump time distributions. PMID:25768477
Coherent adiabatic transport of atoms in radio-frequency traps
Morgan, T.; O'Sullivan, B.; Busch, Th.
2011-05-15
Coherent transport by adiabatic passage has recently been suggested as a high-fidelity technique to engineer the center-of-mass state of single atoms in inhomogeneous environments. While the basic theory behind this process is well understood, several conceptual challenges for its experimental observation have still to be addressed. One of these is the difficulty that currently available optical or magnetic micro-trap systems have in adjusting the tunneling rate time dependently while keeping resonance between the asymptotic trapping states at all times. Here we suggest that both requirements can be fulfilled to a very high degree in an experimentally realistic setup based on radio-frequency traps on atom chips. We show that operations with close to 100% fidelity can be achieved and that these systems also allow significant improvements for performing adiabatic passage with interacting atomic clouds.
Two-mode multiplexer and demultiplexer based on adiabatic couplers.
Xing, Jiejiang; Li, Zhiyong; Xiao, Xi; Yu, Jinzhong; Yu, Yude
2013-09-01
A two-mode (de)multiplexer based on adiabatic couplers is proposed and experimentally demonstrated. The experimental results are in good agreement with the simulations. An ultralow mode cross talk below -36 dB and a low insertion loss of about 0.3 dB over a broad bandwidth from 1500 to 1600 nm are measured. The design is also fabrication-tolerant, and the insertion loss can be further improved in the future. PMID:23988986
Excitation energies along a range-separated adiabatic connection
Rebolini, Elisa Toulouse, Julien Savin, Andreas; Teale, Andrew M.; Helgaker, Trygve
2014-07-28
We present a study of the variation of total energies and excitation energies along a range-separated adiabatic connection. This connection links the non-interacting Kohn–Sham electronic system to the physical interacting system by progressively switching on the electron–electron interactions whilst simultaneously adjusting a one-electron effective potential so as to keep the ground-state density constant. The interactions are introduced in a range-dependent manner, first introducing predominantly long-range, and then all-range, interactions as the physical system is approached, as opposed to the conventional adiabatic connection where the interactions are introduced by globally scaling the standard Coulomb interaction. Reference data are reported for the He and Be atoms and the H{sub 2} molecule, obtained by calculating the short-range effective potential at the full configuration-interaction level using Lieb's Legendre-transform approach. As the strength of the electron–electron interactions increases, the excitation energies, calculated for the partially interacting systems along the adiabatic connection, offer increasingly accurate approximations to the exact excitation energies. Importantly, the excitation energies calculated at an intermediate point of the adiabatic connection are much better approximations to the exact excitation energies than are the corresponding Kohn–Sham excitation energies. This is particularly evident in situations involving strong static correlation effects and states with multiple excitation character, such as the dissociating H{sub 2} molecule. These results highlight the utility of long-range interacting reference systems as a starting point for the calculation of excitation energies and are of interest for developing and analyzing practical approximate range-separated density-functional methodologies.
Adiabaticity and gravity theory independent conservation laws for cosmological perturbations
NASA Astrophysics Data System (ADS)
Romano, Antonio Enea; Mooij, Sander; Sasaki, Misao
2016-04-01
We carefully study the implications of adiabaticity for the behavior of cosmological perturbations. There are essentially three similar but different definitions of non-adiabaticity: one is appropriate for a thermodynamic fluid δPnad, another is for a general matter field δPc,nad, and the last one is valid only on superhorizon scales. The first two definitions coincide if cs2 = cw2 where cs is the propagation speed of the perturbation, while cw2 = P ˙ / ρ ˙ . Assuming the adiabaticity in the general sense, δPc,nad = 0, we derive a relation between the lapse function in the comoving slicing Ac and δPnad valid for arbitrary matter field in any theory of gravity, by using only momentum conservation. The relation implies that as long as cs ≠cw, the uniform density, comoving and the proper-time slicings coincide approximately for any gravity theory and for any matter field if δPnad = 0 approximately. In the case of general relativity this gives the equivalence between the comoving curvature perturbation Rc and the uniform density curvature perturbation ζ on superhorizon scales, and their conservation. This is realized on superhorizon scales in standard slow-roll inflation. We then consider an example in which cw =cs, where δPnad = δPc,nad = 0 exactly, but the equivalence between Rc and ζ no longer holds. Namely we consider the so-called ultra slow-roll inflation. In this case both Rc and ζ are not conserved. In particular, as for ζ, we find that it is crucial to take into account the next-to-leading order term in ζ's spatial gradient expansion to show its non-conservation, even on superhorizon scales. This is an example of the fact that adiabaticity (in the thermodynamic sense) is not always enough to ensure the conservation of Rc or ζ.
Adiabatic pipelining: a key to ternary computing with quantum dots.
Pečar, P; Ramšak, A; Zimic, N; Mraz, M; Lebar Bajec, I
2008-12-10
The quantum-dot cellular automaton (QCA), a processing platform based on interacting quantum dots, was introduced by Lent in the mid-1990s. What followed was an exhilarating period with the development of the line, the functionally complete set of logic functions, as well as more complex processing structures, however all in the realm of binary logic. Regardless of these achievements, it has to be acknowledged that the use of binary logic is in computing systems mainly the end result of the technological limitations, which the designers had to cope with in the early days of their design. The first advancement of QCAs to multi-valued (ternary) processing was performed by Lebar Bajec et al, with the argument that processing platforms of the future should not disregard the clear advantages of multi-valued logic. Some of the elementary ternary QCAs, necessary for the construction of more complex processing entities, however, lead to a remarkable increase in size when compared to their binary counterparts. This somewhat negates the advantages gained by entering the ternary computing domain. As it turned out, even the binary QCA had its initial hiccups, which have been solved by the introduction of adiabatic switching and the application of adiabatic pipeline approaches. We present here a study that introduces adiabatic switching into the ternary QCA and employs the adiabatic pipeline approach to successfully solve the issues of elementary ternary QCAs. What is more, the ternary QCAs presented here are sizewise comparable to binary QCAs. This in our view might serve towards their faster adoption.
Fast quasi-adiabatic gas cooling: an experiment revisited
NASA Astrophysics Data System (ADS)
Oss, S.; Gratton, L. M.; Calzà, G.; López-Arias, T.
2012-09-01
The well-known experiment of the rapid expansion and cooling of the air contained in a bottle is performed with a rapidly responsive, yet very cheap thermometer. The adiabatic, low temperature limit is approached quite closely and measured with our apparatus. A straightforward theoretical model for this process is also presented and discussed. Both the experimental setup and the associated theoretical interpretation of the cooling phenomenon are suited for a standard general physics course at undergraduate level.
Adiabatic expansion of a strongly correlated pure electron plasma
Dubin, D.H.E.; O'Neil, T.M.
1986-02-17
Adiabatic expansion is proposed as a method of increasing the degree of correlation of a magnetically confined pure electron plasma. Quantum mechanical effects and correlation effects make the physics of the expansion quite different from that for a classical ideal gas. The proposed expansion may be useful in a current experimental effort to cool a pure electron plasma to the liquid and solid (crystalline) states.
Adiabatic expansion of a strongly correlated pure electron plasma
NASA Astrophysics Data System (ADS)
Dubin, D. H. E.; Oneil, T. M.
1986-02-01
Adiabatic expansion is proposed as a method of increasing the degree of correlation of a magnetically confined pure electron plasma. Quantum mechanical effects and correlation effects make the physics of the expansion quite different from that for a classical ideal gas. The proposed expansion may be useful in a current experimental effort to cool a pure electron plasma to the liquid and solid (crystalline) states.
Geometric Phase for Adiabatic Evolutions of General Quantum States
Wu, Biao; Liu, Jie; Niu, Qian; Singh, David J
2005-01-01
The concept of a geometric phase (Berry's phase) is generalized to the case of noneigenstates, which is applicable to both linear and nonlinear quantum systems. This is particularly important to nonlinear quantum systems, where, due to the lack of the superposition principle, the adiabatic evolution of a general state cannot be described in terms of eigenstates. For linear quantum systems, our new geometric phase reduces to a statistical average of Berry's phases. Our results are demonstrated with a nonlinear two-level model.
Complete Cycle Experiments Using the Adiabatic Gas Law Apparatus
NASA Astrophysics Data System (ADS)
Kutzner, Mickey D.; Plantak, Mateja
2014-10-01
The ability of our society to make informed energy-usage decisions in the future depends partly on current science and engineering students retaining a deep understanding of the thermodynamics of heat engines. Teacher imaginations and equipment budgets can both be taxed in the effort to engage students in hands-on heat engine activities. The experiments described in this paper, carried out using the Adiabatic Gas Law Apparatus1 (AGLA), quantitatively explore popular complete cycle heat engine processes.
Adiabatic corrections to density functional theory energies and wave functions.
Mohallem, José R; Coura, Thiago de O; Diniz, Leonardo G; de Castro, Gustavo; Assafrão, Denise; Heine, Thomas
2008-09-25
The adiabatic finite-nuclear-mass-correction (FNMC) to the electronic energies and wave functions of atoms and molecules is formulated for density-functional theory and implemented in the deMon code. The approach is tested for a series of local and gradient corrected density functionals, using MP2 results and diagonal-Born-Oppenheimer corrections from the literature for comparison. In the evaluation of absolute energy corrections of nonorganic molecules the LDA PZ81 functional works surprisingly better than the others. For organic molecules the GGA BLYP functional has the best performance. FNMC with GGA functionals, mainly BLYP, show a good performance in the evaluation of relative corrections, except for nonorganic molecules containing H atoms. The PW86 functional stands out with the best evaluation of the barrier of linearity of H2O and the isotopic dipole moment of HDO. In general, DFT functionals display an accuracy superior than the common belief and because the corrections are based on a change of the electronic kinetic energy they are here ranked in a new appropriate way. The approach is applied to obtain the adiabatic correction for full atomization of alcanes C(n)H(2n+2), n = 4-10. The barrier of 1 mHartree is approached for adiabatic corrections, justifying its insertion into DFT. PMID:18537228
Non-adiabatic molecular dynamics by accelerated semiclassical Monte Carlo
White, Alexander J.; Gorshkov, Vyacheslav N.; Tretiak, Sergei; Mozyrsky, Dmitry
2015-07-07
Non-adiabatic dynamics, where systems non-radiatively transition between electronic states, plays a crucial role in many photo-physical processes, such as fluorescence, phosphorescence, and photoisomerization. Methods for the simulation of non-adiabatic dynamics are typically either numerically impractical, highly complex, or based on approximations which can result in failure for even simple systems. Recently, the Semiclassical Monte Carlo (SCMC) approach was developed in an attempt to combine the accuracy of rigorous semiclassical methods with the efficiency and simplicity of widely used surface hopping methods. However, while SCMC was found to be more efficient than other semiclassical methods, it is not yet as efficient as is needed to be used for large molecular systems. Here, we have developed two new methods: the accelerated-SCMC and the accelerated-SCMC with re-Gaussianization, which reduce the cost of the SCMC algorithm up to two orders of magnitude for certain systems. In most cases shown here, the new procedures are nearly as efficient as the commonly used surface hopping schemes, with little to no loss of accuracy. This implies that these modified SCMC algorithms will be of practical numerical solutions for simulating non-adiabatic dynamics in realistic molecular systems.
Numerical study of polaron problem in the adiabatic limit
NASA Astrophysics Data System (ADS)
Marsiglio, Frank; Li, Zhou; Blois, Cindy; Baillie, Devin
2010-03-01
We study the polaron problem in a one dimensional chain and on a two dimensional square lattice. The models we have used are the Holstein model and the Su-Schrieffer-Heeger (SSH) model. By a variational procedure based on the Lanczos method, we are able to examine the polaron problem in the limit when the mass of the ion is very large, i.e. close to the adiabatic limit. It is known that for the Holstein model there is no phase transition [1] for any nonzero phonon energy. It is also known that for the one dimensional Holstein or SSH model there will be long range order [2] (e.g. dimerization) in the adiabatic limit at half-filling. It is then interesting to study the long range order on a two dimensional square lattice in and away from the adiabatic limit. Moreover, recent progress for the single polaron near an impurity (disorder) [3] make it an interesting problem for studying bond length disorder which can change the hopping energy in a specific direction in the Holstein model. Reference: [1] H. Lowen, Phys.Rev.B 37, 8661 (1988) [2] J.E.Hirsch and E. Frandkin, Phys. Rev. Lett. 49, 402 (1982) [3]A.S.Mishchenko et.al Phys.Rev.B 79(2009) 180301(R)
Non-adiabatic molecular dynamics by accelerated semiclassical Monte Carlo.
White, Alexander J; Gorshkov, Vyacheslav N; Tretiak, Sergei; Mozyrsky, Dmitry
2015-07-01
Non-adiabatic dynamics, where systems non-radiatively transition between electronic states, plays a crucial role in many photo-physical processes, such as fluorescence, phosphorescence, and photoisomerization. Methods for the simulation of non-adiabatic dynamics are typically either numerically impractical, highly complex, or based on approximations which can result in failure for even simple systems. Recently, the Semiclassical Monte Carlo (SCMC) approach was developed in an attempt to combine the accuracy of rigorous semiclassical methods with the efficiency and simplicity of widely used surface hopping methods. However, while SCMC was found to be more efficient than other semiclassical methods, it is not yet as efficient as is needed to be used for large molecular systems. Here, we have developed two new methods: the accelerated-SCMC and the accelerated-SCMC with re-Gaussianization, which reduce the cost of the SCMC algorithm up to two orders of magnitude for certain systems. In most cases shown here, the new procedures are nearly as efficient as the commonly used surface hopping schemes, with little to no loss of accuracy. This implies that these modified SCMC algorithms will be of practical numerical solutions for simulating non-adiabatic dynamics in realistic molecular systems. PMID:26156473
Dynamics of Quantum Adiabatic Evolution Algorithm for Number Partitioning
NASA Technical Reports Server (NTRS)
Smelyanskiy, Vadius; vonToussaint, Udo V.; Timucin, Dogan A.; Clancy, Daniel (Technical Monitor)
2002-01-01
We have developed a general technique to study the dynamics of the quantum adiabatic evolution algorithm applied to random combinatorial optimization problems in the asymptotic limit of large problem size n. We use as an example the NP-complete Number Partitioning problem and map the algorithm dynamics to that of an auxiliary quantum spin glass system with the slowly varying Hamiltonian. We use a Green function method to obtain the adiabatic eigenstates and the minimum exitation gap, gmin = O(n2(sup -n/2)), corresponding to the exponential complexity of the algorithm for Number Partitioning. The key element of the analysis is the conditional energy distribution computed for the set of all spin configurations generated from a given (ancestor) configuration by simultaneous flipping of a fixed number of spins. For the problem in question this distribution is shown to depend on the ancestor spin configuration only via a certain parameter related to the energy of the configuration. As the result, the algorithm dynamics can be described in terms of one-dimensional quantum diffusion in the energy space. This effect provides a general limitation of a quantum adiabatic computation in random optimization problems. Analytical results are in agreement with the numerical simulation of the algorithm.
Dynamics of Quantum Adiabatic Evolution Algorithm for Number Partitioning
NASA Technical Reports Server (NTRS)
Smelyanskiy, V. N.; Toussaint, U. V.; Timucin, D. A.
2002-01-01
We have developed a general technique to study the dynamics of the quantum adiabatic evolution algorithm applied to random combinatorial optimization problems in the asymptotic limit of large problem size n. We use as an example the NP-complete Number Partitioning problem and map the algorithm dynamics to that of an auxiliary quantum spin glass system with the slowly varying Hamiltonian. We use a Green function method to obtain the adiabatic eigenstates and the minimum excitation gap. g min, = O(n 2(exp -n/2), corresponding to the exponential complexity of the algorithm for Number Partitioning. The key element of the analysis is the conditional energy distribution computed for the set of all spin configurations generated from a given (ancestor) configuration by simultaneous flipping of a fixed number of spins. For the problem in question this distribution is shown to depend on the ancestor spin configuration only via a certain parameter related to 'the energy of the configuration. As the result, the algorithm dynamics can be described in terms of one-dimensional quantum diffusion in the energy space. This effect provides a general limitation of a quantum adiabatic computation in random optimization problems. Analytical results are in agreement with the numerical simulation of the algorithm.
Conditions for super-adiabatic droplet growth after entrainment mixing
NASA Astrophysics Data System (ADS)
Yang, Fan; Shaw, Raymond; Xue, Huiwen
2016-07-01
Cloud droplet response to entrainment and mixing between a cloud and its environment is considered, accounting for subsequent droplet growth during adiabatic ascent following a mixing event. The vertical profile for liquid water mixing ratio after a mixing event is derived analytically, allowing the reduction to be predicted from the mixing fraction and from the temperature and humidity for both the cloud and environment. It is derived for the limit of homogeneous mixing. The expression leads to a critical height above the mixing level: at the critical height the cloud droplet radius is the same for both mixed and unmixed parcels, and the critical height is independent of the updraft velocity and mixing fraction. Cloud droplets in a mixed parcel are larger than in an unmixed parcel above the critical height, which we refer to as the "super-adiabatic" growth region. Analytical results are confirmed with a bin microphysics cloud model. Using the model, we explore the effects of updraft velocity, aerosol source in the environmental air, and polydisperse cloud droplets. Results show that the mixed parcel is more likely to reach the super-adiabatic growth region when the environmental air is humid and clean. It is also confirmed that the analytical predictions are matched by the volume-mean cloud droplet radius for polydisperse size distributions. The findings have implications for the origin of large cloud droplets that may contribute to onset of collision-coalescence in warm clouds.
Steam bottoming cycle for an adiabatic diesel engine
Poulin, E.; Demler, R.; Krepchin, I.; Walker, D.
1984-03-01
A study of steam bottoming cycles using adiabatic diesel engine exhaust heat projected substantial performance and economic benefits for long haul trucks. A parametric analysis of steam cycle and system component variables, system cost, size and performance was conducted. An 811 K/6.90 MPa state-of-the-art reciprocating expander steam system with a monotube boiler and radiator core condenser was selected for preliminary design. When applied to a NASA specified turbo-charged adiabatic diesel the bottoming system increased the diesel output by almost 18%. In a comparison of the costs of the diesel with bottoming system (TC/B) and a NASA specified turbocompound adiabatic diesel with after-cooling with the same total output, the annual fuel savings less the added maintenance cost was determined to cover the increased initial cost of the TC/B system in a payback period of 2.3 years. Also during this program steam bottoming system freeze protection strategies were developed, technological advances required for improved system reliability were considered and the cost and performance of advanced systems were evaluated.
NMR implementation of adiabatic SAT algorithm using strongly modulated pulses.
Mitra, Avik; Mahesh, T S; Kumar, Anil
2008-03-28
NMR implementation of adiabatic algorithms face severe problems in homonuclear spin systems since the qubit selective pulses are long and during this period, evolution under the Hamiltonian and decoherence cause errors. The decoherence destroys the answer as it causes the final state to evolve to mixed state and in homonuclear systems, evolution under the internal Hamiltonian causes phase errors preventing the initial state to converge to the solution state. The resolution of these issues is necessary before one can proceed to implement an adiabatic algorithm in a large system where homonuclear coupled spins will become a necessity. In the present work, we demonstrate that by using "strongly modulated pulses" (SMPs) for the creation of interpolating Hamiltonian, one can circumvent both the problems and successfully implement the adiabatic SAT algorithm in a homonuclear three qubit system. This work also demonstrates that the SMPs tremendously reduce the time taken for the implementation of the algorithm, can overcome problems associated with decoherence, and will be the modality in future implementation of quantum information processing by NMR. PMID:18376911
NMR implementation of adiabatic SAT algorithm using strongly modulated pulses
NASA Astrophysics Data System (ADS)
Mitra, Avik; Mahesh, T. S.; Kumar, Anil
2008-03-01
NMR implementation of adiabatic algorithms face severe problems in homonuclear spin systems since the qubit selective pulses are long and during this period, evolution under the Hamiltonian and decoherence cause errors. The decoherence destroys the answer as it causes the final state to evolve to mixed state and in homonuclear systems, evolution under the internal Hamiltonian causes phase errors preventing the initial state to converge to the solution state. The resolution of these issues is necessary before one can proceed to implement an adiabatic algorithm in a large system where homonuclear coupled spins will become a necessity. In the present work, we demonstrate that by using "strongly modulated pulses" (SMPs) for the creation of interpolating Hamiltonian, one can circumvent both the problems and successfully implement the adiabatic SAT algorithm in a homonuclear three qubit system. This work also demonstrates that the SMPs tremendously reduce the time taken for the implementation of the algorithm, can overcome problems associated with decoherence, and will be the modality in future implementation of quantum information processing by NMR.
Non-adiabatic molecular dynamics by accelerated semiclassical Monte Carlo
White, Alexander J.; Gorshkov, Vyacheslav N.; Tretiak, Sergei; Mozyrsky, Dmitry
2015-07-07
Non-adiabatic dynamics, where systems non-radiatively transition between electronic states, plays a crucial role in many photo-physical processes, such as fluorescence, phosphorescence, and photoisomerization. Methods for the simulation of non-adiabatic dynamics are typically either numerically impractical, highly complex, or based on approximations which can result in failure for even simple systems. Recently, the Semiclassical Monte Carlo (SCMC) approach was developed in an attempt to combine the accuracy of rigorous semiclassical methods with the efficiency and simplicity of widely used surface hopping methods. However, while SCMC was found to be more efficient than other semiclassical methods, it is not yet as efficientmore » as is needed to be used for large molecular systems. Here, we have developed two new methods: the accelerated-SCMC and the accelerated-SCMC with re-Gaussianization, which reduce the cost of the SCMC algorithm up to two orders of magnitude for certain systems. In many cases shown here, the new procedures are nearly as efficient as the commonly used surface hopping schemes, with little to no loss of accuracy. This implies that these modified SCMC algorithms will be of practical numerical solutions for simulating non-adiabatic dynamics in realistic molecular systems.« less
Adiabatic shear mechanisms for the hard cutting process
NASA Astrophysics Data System (ADS)
Yue, Caixu; Wang, Bo; Liu, Xianli; Feng, Huize; Cai, Chunbin
2015-05-01
The most important consequence of adiabatic shear phenomenon is formation of sawtooth chip. Lots of scholars focused on the formation mechanism of sawtooth, and the research often depended on experimental approach. For the present, the mechanism of sawtooth chip formation still remains some ambiguous aspects. This study develops a combined numerical and experimental approach to get deeper understanding of sawtooth chip formation mechanism for Polycrystalline Cubic Boron Nitride (PCBN) tools orthogonal cutting hard steel GCr15. By adopting the Johnson-Cook material constitutive equations, the FEM simulation model established in this research effectively overcomes serious element distortions and cell singularity in high strain domain caused by large material deformation, and the adiabatic shear phenomenon is simulated successfully. Both the formation mechanism and process of sawtooth are simulated. Also, the change features regarding the cutting force as well as its effects on temperature are studied. More specifically, the contact of sawtooth formation frequency with cutting force fluctuation frequency is established. The cutting force and effect of cutting temperature on mechanism of adiabatic shear are investigated. Furthermore, the effects of the cutting condition on sawtooth chip formation are researched. The researching results show that cutting feed has the most important effect on sawtooth chip formation compared with cutting depth and speed. This research contributes a better understanding of mechanism, feature of chip formation in hard turning process, and supplies theoretical basis for the optimization of hard cutting process parameters.
Non-adiabatic pulsations in %delta; Scuti stars
NASA Astrophysics Data System (ADS)
Moya, A.; Garrido, R.; Dupret, M. A.
2004-01-01
For δ Scuti stars, phase differences and amplitude ratios between the relative effective temperature variation and the relative radial displacement can be derived from multicolor photometric observations. The same quantities can be also calculated from theoretical non-adiabatic pulsation models. We present here these theoretical results, which indicate that non-adiabatic quantities depend on the mixing length parameter α used to treat the convection in the standard Mixing Length Theory (MLT). This dependence can be used to test and to constrain, through multicolor observations, the way MLT describes convection in the outermost layers of the star. We will use the equilibrium models provided by the CESAM evolutionary code. The pulsational observables are calculated by using a non-adiabatic pulsation code developed by R. Garridon and A. Moya. In the evolutionary and pulsation codes, a complete reconstruction of the non-grey atmosphere (Kurucz models) is included. The interaction between pulsation and atmosphere, as described by Dupret et al. (2002), is also included in the code.
Non-adiabatic molecular dynamics by accelerated semiclassical Monte Carlo
White, Alexander J.; Gorshkov, Vyacheslav N.; Tretiak, Sergei; Mozyrsky, Dmitry
2015-07-07
Non-adiabatic dynamics, where systems non-radiatively transition between electronic states, plays a crucial role in many photo-physical processes, such as fluorescence, phosphorescence, and photoisomerization. Methods for the simulation of non-adiabatic dynamics are typically either numerically impractical, highly complex, or based on approximations which can result in failure for even simple systems. Recently, the Semiclassical Monte Carlo (SCMC) approach was developed in an attempt to combine the accuracy of rigorous semiclassical methods with the efficiency and simplicity of widely used surface hopping methods. However, while SCMC was found to be more efficient than other semiclassical methods, it is not yet as efficient as is needed to be used for large molecular systems. Here, we have developed two new methods: the accelerated-SCMC and the accelerated-SCMC with re-Gaussianization, which reduce the cost of the SCMC algorithm up to two orders of magnitude for certain systems. In many cases shown here, the new procedures are nearly as efficient as the commonly used surface hopping schemes, with little to no loss of accuracy. This implies that these modified SCMC algorithms will be of practical numerical solutions for simulating non-adiabatic dynamics in realistic molecular systems.
Irreconcilable difference between quantum walks and adiabatic quantum computing
NASA Astrophysics Data System (ADS)
Wong, Thomas G.; Meyer, David A.
2016-06-01
Continuous-time quantum walks and adiabatic quantum evolution are two general techniques for quantum computing, both of which are described by Hamiltonians that govern their evolutions by Schrödinger's equation. In the former, the Hamiltonian is fixed, while in the latter, the Hamiltonian varies with time. As a result, their formulations of Grover's algorithm evolve differently through Hilbert space. We show that this difference is fundamental; they cannot be made to evolve along each other's path without introducing structure more powerful than the standard oracle for unstructured search. For an adiabatic quantum evolution to evolve like the quantum walk search algorithm, it must interpolate between three fixed Hamiltonians, one of which is complex and introduces structure that is stronger than the oracle for unstructured search. Conversely, for a quantum walk to evolve along the path of the adiabatic search algorithm, it must be a chiral quantum walk on a weighted, directed star graph with structure that is also stronger than the oracle for unstructured search. Thus, the two techniques, although similar in being described by Hamiltonians that govern their evolution, compute by fundamentally irreconcilable means.
Control of Ostwald ripening by using surfactants with high surface modulus.
Tcholakova, Slavka; Mitrinova, Zlatina; Golemanov, Konstantin; Denkov, Nikolai D; Vethamuthu, Martin; Ananthapadmanabhan, K P
2011-12-20
We describe results from systematic measurements of the rate of bubble Ostwald ripening in foams with air volume fraction of 90%. Several surfactant systems, with high and low surface modulus, were used to clarify the effect of the surfactant adsorption layer on the gas permeability across the foam films. In one series of experiments, glycerol was added to the foaming solutions to clarify how changes in the composition of the aqueous phase affect the rate of bubble coarsening. The experimental results are interpreted by a new theoretical model, which allowed us to determine the overall gas permeability of the foam films in the systems studied, and to decompose the film permeability into contributions coming from the surfactant adsorption layers and from the aqueous core of the films. For verification of the theoretical model, the gas permeability determined from the experiments with bulk foams are compared with values, determined in an independent set of measurements with the diminishing bubble method (single bubble attached at large air-water interface) and reasonably good agreement between the results obtained by the two methods is found. The analysis of the experimental data showed that the rate of bubble Ostwald ripening in the studied foams depends on (1) type of used surfactant-surfactants with high surface modulus lead to much slower rate of Ostwald ripening, which is explained by the reduced gas permeability of the adsorption layers in these systems; (2) presence of glycerol which reduces the gas solubility and diffusivity in the aqueous core of the foam film (without affecting the permeability of the adsorption layers), thus also leading to slower Ostwald ripening. Direct measurements showed that the foam films in the studied systems had very similar thicknesses, thus ruling out the possible explanation that the observed differences in the Ostwald ripening are due to different film thicknesses. Experiments with the Langmuir trough were used to demonstrate
Interaction of bone-dental implant with new ultra low modulus alloy using a numerical approach.
Piotrowski, B; Baptista, A A; Patoor, E; Bravetti, P; Eberhardt, A; Laheurte, P
2014-05-01
Although mechanical stress is known as being a significant factor in bone remodeling, most implants are still made using materials that have a higher elastic stiffness than that of bones. Load transfer between the implant and the surrounding bones is much detrimental, and osteoporosis is often a consequence of such mechanical mismatch. The concept of mechanical biocompatibility has now been considered for more than a decade. However, it is limited by the choice of materials, mainly Ti-based alloys whose elastic properties are still too far from cortical bone. We have suggested using a bulk material in relation with the development of a new beta titanium-based alloy. Titanium is a much suitable biocompatible metal, and beta-titanium alloys such as metastable TiNb exhibit a very low apparent elastic modulus related to the presence of an orthorhombic martensite. The purpose of the present work has been to investigate the interaction that occurs between the dental implants and the cortical bone. 3D finite element models have been adopted to analyze the behavior of the bone-implant system depending on the elastic properties of the implant, different types of implant geometry, friction force, and loading condition. The geometry of the bone has been adopted from a mandibular incisor and the surrounding bone. Occlusal static forces have been applied to the implants, and their effects on the bone-metal implant interface region have been assessed and compared with a cortical bone/bone implant configuration. This work has shown that the low modulus implant induces a stress distribution closer to the actual physiological phenomenon, together with a better stress jump along the bone implant interface, regardless of the implant design. PMID:24656363
Novel developments and applications of the classical adiabatic dynamics technique
NASA Astrophysics Data System (ADS)
Rosso, Lula
The present work aims to apply and develop modern molecular dynamics techniques based on a novel analysis of the classical adiabatic dynamics approach. In the first part of this thesis, Car-Parrinello ab-initio molecular dynamics, a successful technique based on adiabatic dynamics, is used to study the charge transport mechanism in solid ammonium perchlorate (AP) crystal exposed to an ammonia-rich environment. AP is a solid-state proton conductor composed of NH+4 and ClO-4 units that can undergo a decomposition process at high temperature, leading to its use such as rocket fuel. After computing IR spectra and carefully analysing the dynamics at different temperatures, we found that the charge transport mechanism in the pure crystal is dominated by diffusion of the ammonium ions and that the translational diffusion is strongly coupled to rotational diffusion of the two types of ions present. When the pure ammonium-perchlorate crystal is doped with neutral ammonia, another mechanism comes into play, namely, the Grotthuss proton hopping mechanism via short-lived N2H+7 complexes. In the second part of this thesis, adiabatic dynamics will be used to develop an alternative approach to the calculation of free energy profiles along reaction paths. The new method (AFED) is based on the creation of an adiabatic separation between the reaction coordinate subspace and the remaining degrees of freedom within a molecular dynamics run. This is achieved by associating with the reaction coordinate(s) a high temperature and large mass. These conditions allow the activated process to occur while permitting the remaining degrees of freedom to respond adiabatically. In this limit, by applying a formal multiple time scale Liouville operator factorization, it can be rigorously shown that the free energy profile is obtained directly from the probability distribution of the reaction coordinate subspace and, therefore, no postprocessing of the output data is required. The new method is
Measurement of Elastic Modulus of Collagen Type I Single Fiber.
Dutov, Pavel; Antipova, Olga; Varma, Sameer; Orgel, Joseph P R O; Schieber, Jay D
2016-01-01
Collagen fibers are the main components of the extra cellular matrix and the primary contributors to the mechanical properties of tissues. Here we report a novel approach to measure the longitudinal component of the elastic moduli of biological fibers under conditions close to those found in vivo and apply it to type I collagen from rat tail tendon. This approach combines optical tweezers, atomic force microscopy, and exploits Euler-Bernoulli elasticity theory for data analysis. This approach also avoids drying for measurements or visualization, since samples are freshly extracted. Importantly, strains are kept below 0.5%, which appear consistent with the linear elastic regime. We find, surprisingly, that the longitudinal elastic modulus of type I collagen cannot be represented by a single quantity but rather is a distribution that is broader than the uncertainty of our experimental technique. The longitudinal component of the single-fiber elastic modulus is between 100 MPa and 360 MPa for samples extracted from different rats and/or different parts of a single tail. Variations are also observed in the fibril-bundle/fibril diameter with an average of 325±40 nm. Since bending forces depend on the diameter to the fourth power, this variation in diameter is important for estimating the range of elastic moduli. The remaining variations in the modulus may be due to differences in composition of the fibril-bundles, or the extent of the proteoglycans constituting fibril-bundles, or that some single fibrils may be of fibril-bundle size. PMID:26800120
The effective Young's modulus of carbon nanotubes in composites.
Deng, Libo; Eichhorn, Stephen J; Kao, Chih-Chuan; Young, Robert J
2011-02-01
A detailed study has been undertaken of the efficiency of reinforcement in nanocomposites consisting of single-walled carbon nanotubes (SWNTs) in poly(vinyl alcohol) (PVA). Nanocomposite fibers have been prepared by electrospinning and their behavior has been compared with nanocomposite films of the same composition. Stress transfer from the polymer matrix to the nanotubes has been followed from stress-induced Raman band shifts, which are shown to be controlled by both geometric factors such as the angles between the nanotube axis, the stressing direction and the direction of laser polarization, and by finite length effects and bundling. A theory has been developed that takes into account all of these factors and enables the behavior of the different forms of nanocomposite, both fibers and films, to be compared in different polarization configurations. The effective modulus of the SWNTs has been found to be in the range 530-700 GPa which, while being impressive, is lower than the generally accepted value of around 1000 GPa as a result of factors such as finite length effects and nanotube bundling. This value of effective modulus has, however, been shown to be consistent with the contribution of nanotubes to the 20% increase in Young's modulus found for the nanocomposite films with a loading of only 0.2% of SWNTs. Hence a self-consistent method has been developed which enables the efficiency of reinforcement by nanotubes, and potentially other high-aspect-ratio nanoparticles, to be evaluated from stress-induced Raman bands shifts in nanocomposites independent of the specimen geometry and laser polarization configuration.
Strength and flexibility of bulk high-{Tc} superconductors
Goretta, K.C.; Jiang, M.; Kupperman, D.S.; Lanagan, M.T.; Singh, J.P.; Vasanthamohan, N.; Hinks, D.G.; Mitchell, J.F.; Richardson, J.W. Jr.
1996-08-01
Strength, fracture toughness, and elastic modulus data have been gathered for bulk high-temperature superconductors, commercial 99.9% Ag, and a 1.2 at.% Mg/Ag alloy. These data have been used to calculate fracture strains for bulk conductors. The calculations indicate that the superconducting cores of clad tapes should begin to fracture at strains below 0.2%. In addition, residual strains in Ag-clad (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} tapes have been measured by neutron diffraction. An explanation is offered for why many tapes appear to be able to tolerate large strains before exhibiting a reduction in current transport.
Medical image fusion by wavelet transform modulus maxima
NASA Astrophysics Data System (ADS)
Guihong, Qu; Dali, Zhang; Pingfan, Yan
2001-08-01
Medical image fusion has been used to derive useful information from multimodality medical image data. In this research, we propose a novel method for multimodality medical image fusion. Using wavelet transform, we achieved a fusion scheme. Afusion rule is proposed and used for calculating the wavelet transformation modulus maxima of input images at different bandwidths and levels. To evaluate the fusion result, a metric based on mutual information (MI) is presented for measuring fusion effect. The performances of other two methods of image fusion based on wavelet transform are briefly described for comparison. The experiment results demonstrate the effectiveness of the fusion scheme.
Mechanical Components from Highly Recoverable, Low Apparent Modulus Materials
NASA Technical Reports Server (NTRS)
Padula, Santo, II (Inventor); Noebe, Ronald D. (Inventor); Stanford, Malcolm K. (Inventor); DellaCorte, Christopher (Inventor)
2015-01-01
A material for use as a mechanical component is formed of a superelastic intermetallic material having a low apparent modulus and a high hardness. The superelastic intermetallic material is conditioned to be dimensionally stable, devoid of any shape memory effect and have a stable superelastic response without irrecoverable deformation while exhibiting strains of at least 3%. The method of conditioning the superelastic intermetallic material is described. Another embodiment relates to lightweight materials known as ordered intermetallics that perform well in sliding wear applications using conventional liquid lubricants and are therefore suitable for resilient, high performance mechanical components such as gears and bearings.
Wavelet transform modulus maxima based fractal correlation analysis
NASA Astrophysics Data System (ADS)
Lin, D. C.; Sharif, A.
2007-12-01
The wavelet transform modulus maxima (WTMM) used in the singularity analysis of one fractal function is extended to study the fractal correlation of two multifractal functions. The technique is developed in the framework of joint partition function analysis (JPFA) proposed by Meneveau et al. [C. Meneveau, K.R. Sreenivasan, Phys. Rev. A 41, 894 (1990)] and is shown to be equally effective. In addition, we show that another leading approach developed for the same purpose, namely, relative multifractal analysis, can be considered as a special case of JPFA at a particular parameter setting.
Hidden modulus in the extended Veneziano-Yankielowicz theory
Auzzi, Roberto; Sannino, Francesco
2005-11-15
The issue of domain walls in the recently extended Veneziano-Yankielowicz theory is investigated and we show that they have an interesting substructure. We also demonstrate the presence of a noncompact modulus. The associated family of degenerate solutions is physically due to the presence of a valley of vacua in the enlarged space of fields. This is a feature of the extended Veneziano-Yankielowicz theory. Unfortunately the above properties do not match the ones expected for the domain walls of N=1 super Yang-Mills.
Kleysteuber, William K.; Mayercheck, William D.
1979-01-01
This disclosure relates to a bulk material handling system particularly adapted for underground mining and includes a monorail supported overhead and carrying a plurality of conveyors each having input and output end portions with the output end portion of a first of the conveyors positioned above an input end portion of a second of the conveyors, a device for imparting motion to the conveyors to move the material from the input end portions toward the output end portions thereof, a device for supporting at least one of the input and output end portions of the first and second conveyors from the monorail, and the supporting device including a plurality of trolleys rollingly supported by the monorail whereby the conveyors can be readily moved therealong.
Bulk Topological Proximity Effect.
Hsieh, Timothy H; Ishizuka, Hiroaki; Balents, Leon; Hughes, Taylor L
2016-02-26
Existing proximity effects stem from systems with a local order parameter, such as a local magnetic moment or a local superconducting pairing amplitude. Here, we demonstrate that despite lacking a local order parameter, topological phases also may give rise to a proximity effect of a distinctively inverted nature. We focus on a general construction in which a topological phase is extensively coupled to a second system, and we argue that, in many cases, the inverse topological order will be induced on the second system. To support our arguments, we rigorously establish this "bulk topological proximity effect" for all gapped free-fermion topological phases and representative integrable models of interacting topological phases. We present a terrace construction which illustrates the phenomenological consequences of this proximity effect. Finally, we discuss generalizations beyond our framework, including how intrinsic topological order may also exhibit this effect.
Liyanage, Chamari R D G; Kodali, Venkata
2014-01-01
The accessibility and usage of body building supplements is on the rise with stronger internet marketing strategies by the industry. The dangers posed by the ingredients in them are underestimated. A healthy young man came to the emergency room with palpitations and feeling unwell. Initial history and clinical examination were non-contributory to find the cause. ECG showed atrial fibrillation. A detailed history for any over the counter or herbal medicine use confirmed that he was taking supplements to bulk muscle. One of the components in these supplements is yohimbine; the onset of symptoms coincided with the ingestion of this product and the patient is symptom free after stopping it. This report highlights the dangers to the public of consuming over the counter products with unknown ingredients and the consequential detrimental impact on health. PMID:25326558
Creating bulk nanocrystalline metal.
Fredenburg, D. Anthony; Saldana, Christopher J.; Gill, David D.; Hall, Aaron Christopher; Roemer, Timothy John; Vogler, Tracy John; Yang, Pin
2008-10-01
Nanocrystalline and nanostructured materials offer unique microstructure-dependent properties that are superior to coarse-grained materials. These materials have been shown to have very high hardness, strength, and wear resistance. However, most current methods of producing nanostructured materials in weapons-relevant materials create powdered metal that must be consolidated into bulk form to be useful. Conventional consolidation methods are not appropriate due to the need to maintain the nanocrystalline structure. This research investigated new ways of creating nanocrystalline material, new methods of consolidating nanocrystalline material, and an analysis of these different methods of creation and consolidation to evaluate their applicability to mesoscale weapons applications where part features are often under 100 {micro}m wide and the material's microstructure must be very small to give homogeneous properties across the feature.
Schwarz, R.B.; Archuleta, J.I.; Sickafus, K.E.
1998-12-01
This is the final report for a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The objective of this work was to develop the competency for the synthesis of novel bulk amorphous alloys. The authors researched their synthesis methods and alloy properties, including thermal stability, mechanical, and transport properties. The project also addressed the development of vanadium-spinel alloys for structural applications in hostile environments, the measurement of elastic constants and thermal expansion in single-crystal TiAl from 300 to 750 K, the measurement of elastic constants in gallium nitride, and a study of the shock-induced martensitic transformations in NiTi alloys.
Miller, Jacob Lee
2015-04-21
An explosive bulk charge, including: a first contact surface configured to be selectively disposed substantially adjacent to a structure or material; a second end surface configured to selectively receive a detonator; and a curvilinear side surface joining the first contact surface and the second end surface. The first contact surface, the second end surface, and the curvilinear side surface form a bi-truncated hemispherical structure. The first contact surface, the second end surface, and the curvilinear side surface are formed from an explosive material. Optionally, the first contact surface and the second end surface each have a substantially circular shape. Optionally, the first contact surface and the second end surface consist of planar structures that are aligned substantially parallel or slightly tilted with respect to one another. The curvilinear side surface has one of a smooth curved geometry, an elliptical geometry, and a parabolic geometry.
Damping and modulus measurements in B2 transition metal aluminides
NASA Technical Reports Server (NTRS)
Harmouche, M. R.; Wolfenden, A.
1985-01-01
The polycrystalline intermetallic alloys FeAl (50.9 to 58.2 percent Fe), NiAl (49.2 to 55.9 percent Ni) and CoAl (48.5 to 52.3 percent Co) have the B2 structure and are of interest for high temperature applications. The PUCOT (piezoelectric ultrasonic composite oscillator technique) has been used to measure mechanical damping or internal friction and Young's modulus has been used as a function of temperature and composition for these materials. The modulus data for six CoAl alloys at temperatures up to 1300 K are presented. Examples are given of the strain amplitude dependence of internal friction for four CoAl alloys. The curves showed the break away phenomenon and are interpreted in terms of a theory dealing with the pinning of dislocation lines and their eventual break away at large strain amplitudes. The dislocation density was calculated to be about 10 to the 8th per sq m. For all the compositions (X1) of CoAl studied, a single equation could be fitted to the data.
Modulus reconstruction from prostate ultrasound images using finite element modeling
NASA Astrophysics Data System (ADS)
Yan, Zhennan; Zhang, Shaoting; Alam, S. Kaisar; Metaxas, Dimitris N.; Garra, Brian S.; Feleppa, Ernest J.
2012-03-01
In medical diagnosis, use of elastography is becoming increasingly more useful. However, treatments usually assume a planar compression applied to tissue surfaces and measure the deformation. The stress distribution is relatively uniform close to the surface when using a large, flat compressor but it diverges gradually along tissue depth. Generally in prostate elastography, the transrectal probes used for scanning and compression are cylindrical side-fire or rounded end-fire probes, and the force is applied through the rectal wall. These make it very difficult to detect cancer in prostate, since the rounded contact surfaces exaggerate the non-uniformity of the applied stress, especially for the distal, anterior prostate. We have developed a preliminary 2D Finite Element Model (FEM) to simulate prostate deformation in elastography. The model includes a homogeneous prostate with a stiffer tumor in the proximal, posterior region of the gland. A force is applied to the rectal wall to deform the prostate, strain and stress distributions can be computed from the resultant displacements. Then, we assume the displacements as boundary condition and reconstruct the modulus distribution (inverse problem) using linear perturbation method. FEM simulation shows that strain and strain contrast (of the lesion) decrease very rapidly with increasing depth and lateral distance. Therefore, lesions would not be clearly visible if located far away from the probe. However, the reconstructed modulus image can better depict relatively stiff lesion wherever the lesion is located.
Low-modulus PMMA bone cement modified with castor oil.
López, Alejandro; Hoess, Andreas; Thersleff, Thomas; Ott, Marjam; Engqvist, Håkan; Persson, Cecilia
2011-01-01
Some of the current clinical and biomechanical data suggest that vertebroplasty causes the development of adjacent vertebral fractures shortly after augmentation. These findings have been attributed to high injection volumes as well as high Young's moduli of PMMA bone cements compared to that of the osteoporotic cancellous bone. The aim of this study was to evaluate the use of castor oil as a plasticizer for PMMA bone cements. The Young's modulus, yield strength, maximum polymerization temperature, doughing time, setting time and the complex viscosity curves during curing, were determined. The cytotoxicity of the materials extracts was assessed on cells of an osteoblast-like cell line. The addition of up to 12 wt% castor oil decreased yield strength from 88 to 15 MPa, Young's modulus from 1500 to 446 MPa and maximum polymerization temperature from 41.3 to 25.6°C, without affecting the setting time. However, castor oil seemed to interfere with the polymerization reaction, giving a negative effect on cell viability in a worst-case scenario.
Stalk Phase Formation: Effects of Dehydration and Saddle Splay Modulus
Kozlovsky, Yonathan; Efrat, Avishay; Siegel, David A.; Kozlov, Michael M.
2004-01-01
One of the earliest lipid intermediates forming in the course of membrane fusion is the lipid stalk. Although many aspects of the stalk hypothesis were elaborated theoretically and confirmed by experiments it remained unresolved whether stalk formation is always an energy consuming process or if there are conditions where the stalks are energetically favorable and form spontaneously resulting in an equilibrium stalk phase. Motivated by a recent breakthrough experiments we analyze the physical factors determining the spontaneous stalk formation. We show that this process can be driven by interplay between two factors: the elastic energy of lipid monolayers including a contribution of the saddle splay deformation and the energy of hydration repulsion acting between apposing membranes. We analyze the dependence of stalk formation on the saddle splay (Gaussian) modulus of the lipid monolayers and estimate the values of this modulus based on the experimentally established phase boundary between the lamellar and the stalk phases. We suggest that fusion proteins can induce stalk formation just by bringing the membranes into close contact, and accumulating, at least locally, a sufficiently large energy of the hydration repulsion. PMID:15454446
Mechanical characterization of bulk Sylgard 184 for microfluidics and microengineering
NASA Astrophysics Data System (ADS)
Johnston, I. D.; McCluskey, D. K.; Tan, C. K. L.; Tracey, M. C.
2014-03-01
Polydimethylsiloxane (PDMS) elastomers are extensively used for soft lithographic replication of microstructures in microfluidic and micro-engineering applications. Elastomeric microstructures are commonly required to fulfil an explicit mechanical role and accordingly their mechanical properties can critically affect device performance. The mechanical properties of elastomers are known to vary with both curing and operational temperatures. However, even for the elastomer most commonly employed in microfluidic applications, Sylgard 184, only a very limited range of data exists regarding the variation in mechanical properties of bulk PDMS with curing temperature. We report an investigation of the variation in the mechanical properties of bulk Sylgard 184 with curing temperature, over the range 25 °C to 200 °C. PDMS samples for tensile and compressive testing were fabricated according to ASTM standards. Data obtained indicates variation in mechanical properties due to curing temperature for Young's modulus of 1.32-2.97 MPa, ultimate tensile strength of 3.51-7.65 MPa, compressive modulus of 117.8-186.9 MPa and ultimate compressive strength of 28.4-51.7 GPa in a range up to 40% strain and hardness of 44-54 ShA.
Influence of viscosity and the adiabatic index on planetary migration
NASA Astrophysics Data System (ADS)
Bitsch, B.; Boley, A.; Kley, W.
2013-02-01
Context. The strength and direction of migration of low mass embedded planets depends on the disk's thermodynamic state. It has been shown that in active disks, where the internal dissipation is balanced by radiative transport, migration can be directed outwards, a process which extends the lifetime of growing embryos. Very important parameters determining the structure of disks, and hence the direction of migration, are the viscosity and the adiabatic index. Aims: In this paper we investigate the influence of different viscosity prescriptions (α-type and constant) and adiabatic indices on disk structures. We then determine how this affects the migration rate of planets embedded in such disks. Methods: We perform three-dimensional numerical simulations of accretion disks with embedded planets. We use the explicit/implicit hydrodynamical code NIRVANA that includes full tensor viscosity and radiation transport in the flux-limited diffusion approximation, as well as a proper equation of state for molecular hydrogen. The migration of embedded 20 MEarth planets is studied. Results: Low-viscosity disks have cooler temperatures and the migration rates of embedded planets tend toward the isothermal limit. Hence, in these disks, planets migrate inwards even in the fully radiative case. The effect of outward migration can only be sustained if the viscosity in the disk is large. Overall, the differences between the treatments for the equation of state seem to play a more important role in disks with higher viscosity. A change in the adiabatic index and in the viscosity changes the zero-torque radius that separates inward from outward migration. Conclusions: For larger viscosities, temperatures in the disk become higher and the zero-torque radius moves to larger radii, allowing outward migration of a 20-MEarth planet to persist over an extended radial range. In combination with large disk masses, this may allow for an extended period of the outward migration of growing
Adiabatic quantum computing with spin qubits hosted by molecules.
Yamamoto, Satoru; Nakazawa, Shigeaki; Sugisaki, Kenji; Sato, Kazunobu; Toyota, Kazuo; Shiomi, Daisuke; Takui, Takeji
2015-01-28
A molecular spin quantum computer (MSQC) requires electron spin qubits, which pulse-based electron spin/magnetic resonance (ESR/MR) techniques can afford to manipulate for implementing quantum gate operations in open shell molecular entities. Importantly, nuclear spins, which are topologically connected, particularly in organic molecular spin systems, are client qubits, while electron spins play a role of bus qubits. Here, we introduce the implementation for an adiabatic quantum algorithm, suggesting the possible utilization of molecular spins with optimized spin structures for MSQCs. We exemplify the utilization of an adiabatic factorization problem of 21, compared with the corresponding nuclear magnetic resonance (NMR) case. Two molecular spins are selected: one is a molecular spin composed of three exchange-coupled electrons as electron-only qubits and the other an electron-bus qubit with two client nuclear spin qubits. Their electronic spin structures are well characterized in terms of the quantum mechanical behaviour in the spin Hamiltonian. The implementation of adiabatic quantum computing/computation (AQC) has, for the first time, been achieved by establishing ESR/MR pulse sequences for effective spin Hamiltonians in a fully controlled manner of spin manipulation. The conquered pulse sequences have been compared with the NMR experiments and shown much faster CPU times corresponding to the interaction strength between the spins. Significant differences are shown in rotational operations and pulse intervals for ESR/MR operations. As a result, we suggest the advantages and possible utilization of the time-evolution based AQC approach for molecular spin quantum computers and molecular spin quantum simulators underlain by sophisticated ESR/MR pulsed spin technology.
Shortcuts to adiabaticity by counterdiabatic driving for trapped-ion displacement in phase space
NASA Astrophysics Data System (ADS)
An, Shuoming; Lv, Dingshun; Del Campo, Adolfo; Kim, Kihwan
2016-09-01
The application of adiabatic protocols in quantum technologies is severely limited by environmental sources of noise and decoherence. Shortcuts to adiabaticity by counterdiabatic driving constitute a powerful alternative that speed up time-evolution while mimicking adiabatic dynamics. Here we report the experimental implementation of counterdiabatic driving in a continuous variable system, a shortcut to the adiabatic transport of a trapped ion in phase space. The resulting dynamics is equivalent to a `fast-motion video' of the adiabatic trajectory. The robustness of this protocol is shown to surpass that of competing schemes based on classical local controls and Fourier optimization methods. Our results demonstrate that shortcuts to adiabaticity provide a robust speedup of quantum protocols of wide applicability in quantum technologies.
Kibble-Zurek mechanism beyond adiabaticity: Finite-time scaling with critical initial slip
NASA Astrophysics Data System (ADS)
Huang, Yingyi; Yin, Shuai; Hu, Qijun; Zhong, Fan
2016-01-01
The Kibble-Zurek mechanism demands an initial adiabatic stage before an impulse stage to have a frozen correlation length that generates topological defects in a cooling phase transition. Here we study such a driven critical dynamics but with an initial condition that is near the critical point and that is far away from equilibrium. In this case, there is no initial adiabatic stage at all and thus adiabaticity is broken. However, we show that there again exists a finite length scale arising from the driving that divides the evolution into three stages. A relaxation-finite-time-scaling-adiabatic scenario is then proposed in place of the adiabatic-impulse-adiabatic scenario of the original Kibble-Zurek mechanism. A unified scaling theory, which combines finite-time scaling with critical initial slip, is developed to describe the universal behavior and is confirmed with numerical simulations of a two-dimensional classical Ising model.
Effect of Grain Boundary Character Distribution on the Adiabatic Shear Susceptibility
NASA Astrophysics Data System (ADS)
Yang, Yang; Jiang, Lihong; Luo, Shuhong; Hu, Haibo; Tang, Tiegang; Zhang, Qingming
2016-11-01
The adiabatic shear susceptibility of AISI321 stainless steels with different grain boundary character distributions (GBCDs) was investigated by means of split-Hopkinson pressure bar. The results indicate that the width of the adiabatic shear band of the specimen after thermomechanical processing (TMP) treatment is narrower. The comparison of the stress collapse time, the critical stress, and the adiabatic shear forming energy suggests that the TMP specimens have lower adiabatic shear susceptibility than that of the solution-treated samples under the same loading condition. GBCD and grain size affected the adiabatic shear susceptibility. The high-angle boundary network of the TMP specimens was interrupted or replaced by the special grain boundary, and smaller grain size hindered the adiabatic shearing.
Shortcuts to adiabaticity by counterdiabatic driving for trapped-ion displacement in phase space
An, Shuoming; Lv, Dingshun; del Campo, Adolfo; Kim, Kihwan
2016-01-01
The application of adiabatic protocols in quantum technologies is severely limited by environmental sources of noise and decoherence. Shortcuts to adiabaticity by counterdiabatic driving constitute a powerful alternative that speed up time-evolution while mimicking adiabatic dynamics. Here we report the experimental implementation of counterdiabatic driving in a continuous variable system, a shortcut to the adiabatic transport of a trapped ion in phase space. The resulting dynamics is equivalent to a ‘fast-motion video' of the adiabatic trajectory. The robustness of this protocol is shown to surpass that of competing schemes based on classical local controls and Fourier optimization methods. Our results demonstrate that shortcuts to adiabaticity provide a robust speedup of quantum protocols of wide applicability in quantum technologies. PMID:27669897
From Classical Nonlinear Integrable Systems to Quantum Shortcuts to Adiabaticity.
Okuyama, Manaka; Takahashi, Kazutaka
2016-08-12
Using shortcuts to adiabaticity, we solve the time-dependent Schrödinger equation that is reduced to a classical nonlinear integrable equation. For a given time-dependent Hamiltonian, the counterdiabatic term is introduced to prevent nonadiabatic transitions. Using the fact that the equation for the dynamical invariant is equivalent to the Lax equation in nonlinear integrable systems, we obtain the counterdiabatic term exactly. The counterdiabatic term is available when the corresponding Lax pair exists and the solvable systems are classified in a unified and systematic way. Multisoliton potentials obtained from the Korteweg-de Vries equation and isotropic XY spin chains from the Toda equations are studied in detail.
From Classical Nonlinear Integrable Systems to Quantum Shortcuts to Adiabaticity
NASA Astrophysics Data System (ADS)
Okuyama, Manaka; Takahashi, Kazutaka
2016-08-01
Using shortcuts to adiabaticity, we solve the time-dependent Schrödinger equation that is reduced to a classical nonlinear integrable equation. For a given time-dependent Hamiltonian, the counterdiabatic term is introduced to prevent nonadiabatic transitions. Using the fact that the equation for the dynamical invariant is equivalent to the Lax equation in nonlinear integrable systems, we obtain the counterdiabatic term exactly. The counterdiabatic term is available when the corresponding Lax pair exists and the solvable systems are classified in a unified and systematic way. Multisoliton potentials obtained from the Korteweg-de Vries equation and isotropic X Y spin chains from the Toda equations are studied in detail.
Salt materials testing for a spacecraft adiabatic demagnetization refrigerator
NASA Astrophysics Data System (ADS)
Savage, M. L.; Kittel, P.; Roellig, T.
As part of a technology development effort to qualify adiabatic demagnetization refrigerators for use in a NASA spacecraft, such as the Space Infrared Telescope Facility, a study of low temperature characteristics, heat capacity and resistance to dehydration was conducted for different salt materials. This report includes results of testing with cerrous metaphosphate, several synthetic rubies, and chromic potassium alum (CPA). Preliminary results show that CPA may be suitable for long-term spacecraft use, provided that the salt is property encapsulated. Methods of salt pill construction and testing for all materials are discussed, as well as reliability tests. Also, the temperature regulation scheme and the test cryostat design are briefly discussed.
Magnetic shielding for a spaceborne adiabatic demagnetization refrigerator (ADR)
NASA Technical Reports Server (NTRS)
Warner, Brent A.; Shirron, Peter J.; Castles, Stephen H.; Serlemitsos, Aristides T.
1991-01-01
The Goddard Space Flight Center has studied magnetic shielding for an adiabatic demagnetization refrigerator. Four types of shielding were studied: active coils, passive ferromagnetic shells, passive superconducting coils, and passive superconducting shells. The passive superconducting shells failed by allowing flux penetration. The other three methods were successful, singly or together. Experimental studies of passive ferromagnetic shielding are compared with calculations made using the Poisson Group of programs, distributed by the Los Alamos Accelerator Code Group of the Los Alamos National Laboratory. Agreement between calculation and experiment is good. The ferromagnetic material is a silicon iron alloy.
More bang for your buck: Super-adiabatic quantum engines
Campo, A. del; Goold, J.; Paternostro, M.
2014-01-01
The practical untenability of the quasi-static assumption makes any realistic engine intrinsically irreversible and its operating time finite, thus implying friction effects at short cycle times. An important technological goal is thus the design of maximally efficient engines working at the maximum possible power. We show that, by utilising shortcuts to adiabaticity in a quantum engine cycle, one can engineer a thermodynamic cycle working at finite power and zero friction. Our findings are illustrated using a harmonic oscillator undergoing a quantum Otto cycle. PMID:25163421
Non-Adiabatic Holonomic Quantum Gates in an atomic system
NASA Astrophysics Data System (ADS)
Azimi Mousolou, Vahid; Canali, Carlo M.; Sjoqvist, Erik
2012-02-01
Quantum computation is essentially the implementation of a universal set of quantum gate operations on a set of qubits, which is reliable in the presence of noise. We propose a scheme to perform robust gates in an atomic four-level system using the idea of non-adiabatic holonomic quantum computation proposed in [1]. The gates are realized by applying sequences of short laser pulses that drive transitions between the four energy levels in such a way that the dynamical phases vanish. [4pt] [1] E. Sjoqvist, D.M. Tong, B. Hessmo, M. Johansson, K. Singh, arXiv:1107.5127v2 [quant-ph
Gravitational radiation reaction and inspiral waveforms in the adiabatic limit.
Hughes, Scott A; Drasco, Steve; Flanagan, Eanna E; Franklin, Joel
2005-06-10
We describe progress evolving an important limit of binaries in general relativity: stellar mass compact objects spiraling into much larger black holes. Such systems are of great observational interest. We have developed tools to compute for the first time the radiation from generic orbits. Using global conservation laws, we find the orbital evolution and waveforms for special cases. For generic orbits, inspirals and waveforms can be found by augmenting our approach with an adiabatic self-force rule due to Mino. Such waveforms should be accurate enough for gravitational-wave searches. PMID:16090377
Relativistic blast waves in two dimensions. I - The adiabatic case
NASA Technical Reports Server (NTRS)
Shapiro, P. R.
1979-01-01
Approximate solutions are presented for the dynamical evolution of strong adiabatic relativistic blast waves which result from a point explosion in an ambient gas in which the density varies both with distance from the explosion center and with polar angle in axisymmetry. Solutions are analytical or quasi-analytical for the extreme relativistic case and numerical for the arbitrarily relativistic case. Some general properties of nonplanar relativistic shocks are also discussed, including the incoherence of spherical ultrarelativistic blast-wave fronts on angular scales greater than the reciprocal of the shock Lorentz factor, as well as the conditions for producing blast-wave acceleration.
Optimized sympathetic cooling of atomic mixtures via fast adiabatic strategies
Choi, Stephen; Sundaram, Bala; Onofrio, Roberto
2011-11-15
We discuss fast frictionless cooling techniques in the framework of sympathetic cooling of cold atomic mixtures. It is argued that optimal cooling of an atomic species--in which the deepest quantum degeneracy regime is achieved--may be obtained by means of sympathetic cooling with another species whose trapping frequency is dynamically changed to maintain constancy of the Lewis-Riesenfeld adiabatic invariant. Advantages and limitations of this cooling strategy are discussed, with particular regard to the possibility of cooling Fermi gases to a deeper degenerate regime.
Salt materials testing for a spacecraft adiabatic demagnetization refrigerator
NASA Technical Reports Server (NTRS)
Savage, M. L.; Kittel, P.; Roellig, T.
1990-01-01
As part of a technology development effort to qualify adiabatic demagnetization refrigerators for use in a NASA spacecraft, such as the Space Infrared Telescope Facility, a study of low temperature characteristics, heat capacity and resistance to dehydration was conducted for different salt materials. This report includes results of testing with cerrous metaphosphate, several synthetic rubies, and chromic potassium alum (CPA). Preliminary results show that CPA may be suitable for long-term spacecraft use, provided that the salt is property encapsulated. Methods of salt pill construction and testing for all materials are discussed, as well as reliability tests. Also, the temperature regulation scheme and the test cryostat design are briefly discussed.
Mysterious dipole synchrotron oscillations during and after adiabatic capture
Ng, K.Y.; /Fermilab
2012-03-01
Strong synchrotron oscillations were observed during and after the 2.5-MHz rf adiabatic capture of a debunched booster batch in the Main Injector. Analysis shows two possible sources for the synchrotron oscillations. One is the frequency drift of the 2.5-MHz rf after the turning off of the 53-MHz rf voltage, thus resulting in an energy mismatch with the debunched beam. The second source is the energy mismatch of the injected booster beam with the frequency of the 53-MHz rf. We have been able to rule out the first possibility.
Adiabatic regularization of power spectra in nonminimally coupled chaotic inflation
NASA Astrophysics Data System (ADS)
Alinea, Allan L.
2016-10-01
We investigate the effect of adiabatic regularization on both the tensor- and scalar-perturbation power spectra in nonminimally coupled chaotic inflation. Similar to that of the minimally coupled general single-field inflation, we find that the subtraction term is suppressed by an exponentially decaying factor involving the number of e -folds. By following the subtraction term long enough beyond horizon crossing, the regularized power spectrum tends to the ``bare'' power spectrum. This study justifies the use of the unregularized (``bare'') power spectrum in standard calculations.
Adiabatic invariants in stellar dynamics. 2: Gravitational shocking
NASA Technical Reports Server (NTRS)
Weinberg, Martin D.
1994-01-01
A new theory of gravitational shocking based on time-dependent perturbation theory shows that the changes in energy and angular momentum due to a slowly varying disturbance are not exponentially small for stellar dynamical systems in general. It predicts significant shock heating by slowly varying perturbations previously thought to be negligible according to the adiabatic criterion. The theory extends the scenarios traditionally computed only with the impulse approximation and is applicable to a wide class of disturbances. The approach is applied specifically to the problem of disk shocking of star clusters.
Fast CNOT gate via shortcuts to adiabatic passage
NASA Astrophysics Data System (ADS)
Wang, Zhe; Xia, Yan; Chen, Ye-Hong; Song, Jie
2016-10-01
Based on the shortcuts to adiabatic passage, we propose a scheme for directly implementing a controlled-not (CNOT) gate in a cavity quantum electrodynamics system. Moreover, we generalize the scheme to realize a CNOT gate in two separate cavities connected by an optical fiber. The strictly numerical simulation shows that the schemes are fast and insensitive to the decoherence caused by atomic spontaneous emission and photon leakage. In addition, the schemes can provide a theoretical basis for the manipulation of the multiqubit quantum gates in distant nodes of a quantum network.
Major Steps in the Discovery of Adiabatic Shear Bands
NASA Astrophysics Data System (ADS)
Dodd, Bradley; Walley, Stephen M.; Yang, Rong; Nesterenko, Vitali F.
2015-10-01
The standard story of the discovery of adiabatic shear bands is that it began with the American researchers Zener and Hollomon's famous 1944 paper where the phenomenon was first reported and named. However, a recent discovery by one of us (SMW) in the Cambridge University Library has shown that the phenomenon was discovered and described by a Russian researcher, V.P. Kravz-Tarnavskii, in 1928. A follow-up paper was published by two of his colleagues in 1935. Translations of the 1928 and 1935 papers may be found at http://arxiv.org/abs/1410.1353.
Non-adiabatic pumping in an oscillating-piston model
NASA Astrophysics Data System (ADS)
Chuchem, Maya; Dittrich, Thomas; Cohen, Doron
2012-05-01
We consider the prototypical "piston pump" operating on a ring, where a circulating current is induced by means of an AC driving. This can be regarded as a generalized Fermi-Ulam model, incorporating a finite-height moving wall (piston) and non-trivial topology (ring). The amount of particles transported per cycle is determined by a layered structure of phase space. Each layer is characterized by a different drift velocity. We discuss the differences compared with the adiabatic and Boltzmann pictures, and highlight the significance of the "diabatic" contribution that might lead to a counter-stirring effect.
Stimulated Raman adiabatic passage in Tm{sup 3+}:YAG
Alexander, A. L.; Lauro, R.; Louchet, A.; Chaneliere, T.; Le Goueet, J. L.
2008-10-01
We report on the experimental demonstration of stimulated Raman adiabatic passage in a Tm{sup 3+}:YAG crystal. Tm{sup 3+}:YAG is a promising material for use in quantum information processing applications, but as yet there are few experimental investigations of coherent Raman processes in this material. We investigate the effect of inhomogeneous broadening and Rabi frequency on the transfer efficiency and the width of the two-photon spectrum. Simulations of the complete Tm{sup 3+}:YAG system are presented along with the corresponding experimental results.
NASA Technical Reports Server (NTRS)
Bacon, J. F.
1971-01-01
Emphasis on the consideration of glass formation on a kinetic process made it possible to think of glass compositions different from those normally employed in the manufacture of glass fibers. Approximately 450 new glass compositions were prepared and three dozen of these compositions have values for Young's modulus measured on bulk specimens greater than nineteen million pounds per square inch. Of the new glasses about a hundred could be drawn into fibers by mechanical methods at high speeds. The fiber which has a Young's modulus measured on the fiber of 18.6 million pounds per square inch and has been prepared in quantity as a monofilament (to date more than 150 million lineal feet of 0.2 to 0.4 mil fiber have been produced). This fiber has also been successfully incorporated both in epoxy and polyimide matrices. The epoxy resin composite has shown a modulus forty percent better than that achievable using the most common grade of competitive glass fiber, and twenty percent better than that obtainable with the best available grade of competitive glass fiber. Other glass fibers of even higher modulus have been developed.
NASA Technical Reports Server (NTRS)
Malu, M.; Tien, J. K.
1975-01-01
The effect of elastic modulus and the temperature dependence of elastic modulus on creep activation energies for an oxide dispersion strengthened nickel-base superalloy are investigated. This superalloy is commercially known as Inconel Alloy MA 753, strengthened both by gamma-prime precipitates and by yttria particles. It is shown that at intermediate temperatures, say below 1500 F, where elastic modulus is weakly dependent on temperature, the modulus correction term to creep activation energy is small. Accordingly, modulus corrections are insignificant for the superalloy considered, which shows high apparent creep activation energies at this temperature. On the contrary, at very high temperatures, the elastic modulus correction term can be significant, thus reducing the creep activation energy to that of vacancy self-diffusion. In order to obtain high-temperature creep resistance, a high-value elastic modulus with a weak dependence on temperature is required.
Shortcut to Adiabatic Passage in Two- and Three-Level Atoms
Chen Xi; Lizuain, I.; Muga, J. G.; Ruschhaupt, A.; Guery-Odelin, D.
2010-09-17
We propose a method to speed up adiabatic passage techniques in two-level and three-level atoms extending to the short-time domain their robustness with respect to parameter variations. It supplements or substitutes the standard laser beam setups with auxiliary pulses that steer the system along the adiabatic path. Compared to other strategies, such as composite pulses or the original adiabatic techniques, it provides a fast and robust approach to population control.
2011-01-03
Bulk Data Mover (BDM) is a high-level data transfer management tool. BDM handles the issue of large variance in file sizes and a big portion of small files by managing the file transfers with optimized transfer queue and concurrency management algorithms. For example, climate simulation data sets are characterized by large volume of files with extreme variance in file sizes. The BDN achieves high performance using a variety of techniques, including multi-thraded concurrent transfer connections, data channel caching, load balancing over multiple transfer servers, and storage i/o pre-fetching. Logging information from the BDM is collected and analyzed to study the effectiveness of the transfer management algorithms. The BDM can accept a request composed of multiple files or an entire directory. The request also contains the target site and directory where the replicated files will reside. If a directory is provided at the source, then the BDM will replicate the structure of the source directory at the target site. The BDM is capable of transferring multiple files concurrently as well as using parallel TCP streams. The optimal level of concurrency or parallel streams depends on the bandwidth capacity of the storage systems at both ends of the transfer as well as achievable bandwidth of the wide-area network. Hardware req.-PC, MAC, Multi-platform & Workstation; Software req.: Compile/version-Java 1.50_x or ablove; Type of files: source code, executable modules, installation instructions other, user guide; URL: http://sdm.lbl.gov/bdm/
NASA Astrophysics Data System (ADS)
Wójcik, P.; Zegrodnik, M.; Rzeszotarski, B.; Adamowski, J.
2016-09-01
The tunneling conductance through the half-metal/conical magnet/superconductor (HM/CM/SC) junctions is investigated with the use of the Bogoliubov-de Gennes equations in the framework of Blonder-Tinkham-Klapwijk formalism. Due to the spin band separation in the HM, the conductance in the subgap region is mainly determined by the anomalous Andreev reflection, the probability of which strongly depends on the spin transmission in the CM layer. We show that the spins of electrons injected from the HM can be transmitted through the CM to the SC either adiabatically or non-adiabatically depending on the period of the spatial modulation of the exchange field. We find that the conductance in the subgap region oscillates as a function of the CM layer thickness wherein the oscillations transform from the irregular pattern in the non-adiabatic regime to the regular one in the adiabatic regime. For both adiabatic and non-adiabatic transport regimes the conductance is studied over a broad range of parameters determining the spiral magnetization in the CM. We find that in the non-adiabatic regime, the decrease of the exchange field amplitude in the CM leads to the emergence of the conductance peak for the particular CM thickness in agreement with recent experiments.
In vivo performance of a reduced-modulus bone cement
NASA Astrophysics Data System (ADS)
Forehand, Brett Ramsey
Total joint replacement has become one of the most common procedures in the area of orthopedics and is often the solution in patients with diseased or injured hip joints. Component loosening is a significant problem and is primarily caused by bone resorption at the bone-cement interface in cemented implants. It is our hypothesis that localized shear stresses are responsible for the resorption. It was previously shown analytically that local stresses at the interface could be reduced by using a cement of lower modulus. A new reduced modulus cement, polybutyl methylmethacrylate (PBMMA), was developed to test the hypothesis. PBMMA was formulated to exist as polybutyl methacrylate filler in a polymethyl methacrylate matrix. The success of PBMMA cement is based largely on the fact that the polybutyl component of the cement will be in the rubbery state at body temperature. In vitro characterization of the cement was undertaken previously and demonstrated a modulus of approximately one-eighth that of conventional bone cement, polymethyl methacrylate (PMMA) and increased fracture toughness. The purpose of this experiment was to perform an in vivo comparison of the two cements. A sheep model was selected. Total hip arthroplasty was performed on 50 ewes using either PBMMA or PMMA. Radiographs were taken at 6 month intervals. At one year, the contralateral femur of each sheep was implanted so that each animal served as its own control, and the animals were sacrificed. The stiffness of the bone-cement interface of the femoral component within the femur was assessed by applying a torque to the femoral component and demonstrated a significant difference in loosening between the cements when the specimens were tested in external rotation (p < 0.007). Evaluation of the mechanical data also suggests that the PBMMA sheep had a greater amount of loosening for each subject, 59% versus 4% for standard PMMA. A radiographic analysis demonstrated more signs of loosening in the PMMA series
Experimental study of the validity of quantitative conditions in the quantum adiabatic theorem.
Du, Jiangfeng; Hu, Lingzhi; Wang, Ya; Wu, Jianda; Zhao, Meisheng; Suter, Dieter
2008-08-01
The quantum adiabatic theorem plays an important role in quantum mechanics. However, counter-examples were produced recently, indicating that their transition probabilities do not converge as predicted by the adiabatic theorem [K. P. Marzlin et al., Phys. Rev. Lett. 93, 160408 (2004); D. M. Tong et al., Phys. Rev. Lett. 95, 110407 (2005)]. For a special class of Hamiltonians, we examine the standard criterion for adiabatic evolution experimentally and theoretically, as well as three newly suggested adiabatic conditions. We show that the standard criterion is neither sufficient nor necessary.
Singularity of the time-energy uncertainty in adiabatic perturbation and cycloids on a Bloch sphere
Oh, Sangchul; Hu, Xuedong; Nori, Franco; Kais, Sabre
2016-01-01
Adiabatic perturbation is shown to be singular from the exact solution of a spin-1/2 particle in a uniformly rotating magnetic field. Due to a non-adiabatic effect, its quantum trajectory on a Bloch sphere is a cycloid traced by a circle rolling along an adiabatic path. As the magnetic field rotates more and more slowly, the time-energy uncertainty, proportional to the length of the quantum trajectory, calculated by the exact solution is entirely different from the one obtained by the adiabatic path traced by the instantaneous eigenstate. However, the non-adiabatic Aharonov- Anandan geometric phase, measured by the area enclosed by the exact path, approaches smoothly the adiabatic Berry phase, proportional to the area enclosed by the adiabatic path. The singular limit of the time-energy uncertainty and the regular limit of the geometric phase are associated with the arc length and arc area of the cycloid on a Bloch sphere, respectively. Prolate and curtate cycloids are also traced by different initial states outside and inside of the rolling circle, respectively. The axis trajectory of the rolling circle, parallel to the adiabatic path, is shown to be an example of transitionless driving. The non-adiabatic resonance is visualized by the number of cycloid arcs. PMID:26916031
Singularity of the time-energy uncertainty in adiabatic perturbation and cycloids on a Bloch sphere.
Oh, Sangchul; Hu, Xuedong; Nori, Franco; Kais, Sabre
2016-01-01
Adiabatic perturbation is shown to be singular from the exact solution of a spin-1/2 particle in a uniformly rotating magnetic field. Due to a non-adiabatic effect, its quantum trajectory on a Bloch sphere is a cycloid traced by a circle rolling along an adiabatic path. As the magnetic field rotates more and more slowly, the time-energy uncertainty, proportional to the length of the quantum trajectory, calculated by the exact solution is entirely different from the one obtained by the adiabatic path traced by the instantaneous eigenstate. However, the non-adiabatic Aharonov-Anandan geometric phase, measured by the area enclosed by the exact path, approaches smoothly the adiabatic Berry phase, proportional to the area enclosed by the adiabatic path. The singular limit of the time-energy uncertainty and the regular limit of the geometric phase are associated with the arc length and arc area of the cycloid on a Bloch sphere, respectively. Prolate and curtate cycloids are also traced by different initial states outside and inside of the rolling circle, respectively. The axis trajectory of the rolling circle, parallel to the adiabatic path, is shown to be an example of transitionless driving. The non-adiabatic resonance is visualized by the number of cycloid arcs. PMID:26916031
Size dependent elastic modulus and mechanical resilience of dental enamel.
O'Brien, Simona; Shaw, Jeremy; Zhao, Xiaoli; Abbott, Paul V; Munroe, Paul; Xu, Jiang; Habibi, Daryoush; Xie, Zonghan
2014-03-21
Human tooth enamel exhibits a unique microstructure able to sustain repeated mechanical loading during dental function. Although notable advances have been made towards understanding the mechanical characteristics of enamel, challenges remain in the testing and interpretation of its mechanical properties. For example, enamel was often tested under dry conditions, significantly different from its native environment. In addition, constant load, rather than indentation depth, has been used when mapping the mechanical properties of enamel. In this work, tooth specimens are prepared under hydrated conditions and their stiffnesses are measured by depth control across the thickness of enamel. Crystal arrangement is postulated, among other factors, to be responsible for the size dependent indentation modulus of enamel. Supported by a simple structure model, effective crystal orientation angle is calculated and found to facilitate shear sliding in enamel under mechanical contact. In doing so, the stress build-up is eased and structural integrity is maintained.
Young's modulus of BF wood material by longitudinal vibration
NASA Astrophysics Data System (ADS)
Phadke, Sushil; Darshan Shrivastava, Bhakt; Mishra, Ashutosh; Dagaonkar, N.
2014-09-01
All engineered structures are designed and built with consideration of resisting the same fundamental forces of tension, compression, shear, bending and torsion. Structural design is a balance of these internal and external forces. So, it is interesting to calculate the Young's moduli of Borassus Flabellifier BF wood are quite important from the application point of view. The ultrasonic waves are closely related with the elastic and inelastic properties of the materials. In the present study, we measured longitudinal wave ultrasonic velocities in BF wood material by longitudinal vibration method. After measuring ultrasonic velocity in BF wood material, we calculated Young's modulus of Borassus Flabellifier BF wood material. We used ultrasonic interferometer for measuring longitudinal wave ultrasonic velocity in BF wood material made by Mittal Enterprises, New Delhi, India in our laboratory. Borassus Flabellifier BF wood material was collected from Dhar district of Madhya Pradesh, India.
DEM interpolation weight calculation modulus based on maximum entropy
NASA Astrophysics Data System (ADS)
Chen, Tian-wei; Yang, Xia
2015-12-01
There is negative-weight in traditional interpolation of gridding DEM, in the article, the principle of Maximum Entropy is utilized to analyze the model system which depends on modulus of space weight. Negative-weight problem of the DEM interpolation is researched via building Maximum Entropy model, and adding nonnegative, first and second order's Moment constraints, the negative-weight problem is solved. The correctness and accuracy of the method was validated with genetic algorithm in matlab program. The method is compared with the method of Yang Chizhong interpolation and quadratic program. Comparison shows that the volume and scaling of Maximum Entropy's weight is fit to relations of space and the accuracy is superior to the latter two.
Young’s modulus of [111] germanium nanowires
Maksud, M.; Yoo, J.; Harris, C. T.; Palapati, N. K. R.; Subramanian, A.
2015-11-02
Our paper reports a diameter-independent Young’s modulus of 91.9 ± 8.2 GPa for [111] Germanium nanowires (Ge NWs). When the surface oxide layer is accounted for using a core-shell NW approximation, the YM of the Ge core approaches a near theoretical value of 147.6 ± 23.4 GPa. The ultimate strength of a NW device was measured at 10.9 GPa, which represents a very high experimental-to-theoretical strength ratio of ~75%. Furthermore, with increasing interest in this material system as a high-capacity lithium-ion battery anode, the presented data provide inputs that are essential in predicting its lithiation-induced stress fields and fracture behavior.
Young’s modulus of [111] germanium nanowires
Maksud, M.; Palapati, N. K. R.; Subramanian, A.; Yoo, J.; Harris, C. T.
2015-11-01
This paper reports a diameter-independent Young’s modulus of 91.9 ± 8.2 GPa for [111] Germanium nanowires (Ge NWs). When the surface oxide layer is accounted for using a core-shell NW approximation, the YM of the Ge core approaches a near theoretical value of 147.6 ± 23.4 GPa. The ultimate strength of a NW device was measured at 10.9 GPa, which represents a very high experimental-to-theoretical strength ratio of ∼75%. With increasing interest in this material system as a high-capacity lithium-ion battery anode, the presented data provide inputs that are essential in predicting its lithiation-induced stress fields and fracture behavior.
High modulus liquid crystalline thermosetting resins through novel processing techniques
Smith, M.E.; Douglas, E.P.; Benicewicz, B.C.; Earls, J.D.; Priester, R.D. Jr.
1996-05-01
The authors have demonstrated the effects of magnetic field alignment for the epoxy resin system, the diglycidyl ether of dihydroxy-{alpha}-methylstilbene cured with sulfanilamide. With increasing magnetic field, the tensile modulus of the thermoset can be enhanced by a factor of three, without compromise to the transverse value. Measurements of the coefficients of thermal expansion and the order parameter as determined by x-ray diffraction elucidate the high degree of alignment obtained at field strengths of 15--18 Tesla. The interrelationship between the reaction kinetics of curing with the molecular alignment process is central to successful processing of this class of thermosets. Preliminary relationships between the field strength, time in the magnetic field, reaction rate, and extent of reaction have been developed. Process control and sequencing allow a wide adjustment in the properties of the produced samples. These studies demonstrate the increased value of multi-mode processing in the development of tailored property, lightweight materials.
Enhanced diffusion weighting generated by selective adiabatic pulse trains
NASA Astrophysics Data System (ADS)
Sun, Ziqi; Bartha, Robert
2007-09-01
A theoretical description and experimental validation of the enhanced diffusion weighting generated by selective adiabatic full passage (AFP) pulse trains is provided. Six phantoms (Ph-1-Ph-6) were studied on a 4 T Varian/Siemens whole body MRI system. Phantoms consisted of 2.8 cm diameter plastic tubes containing a mixture of 10 μm ORGASOL polymer beads and 2 mM Gd-DTPA dissolved in 5% agar (Ph-1) or nickel(II) ammonium sulphate hexahydrate doped (56.3-0.8 mM) water solutions (Ph-2-Ph-6). A customized localization by adiabatic selective refocusing (LASER) sequence containing slice selective AFP pulse trains and pulsed diffusion gradients applied in the phase encoding direction was used to measure 1H 2O diffusion. The b-value associated with the LASER sequence was derived using the Bloch-Torrey equation. The apparent diffusion coefficients measured by LASER were comparable to those measured by a conventional pulsed gradient spin-echo (PGSE) sequence for all phantoms. Image signal intensity increased in Ph-1 and decreased in Ph-2-Ph-6 as AFP pulse train length increased while maintaining a constant echo-time. These experimental results suggest that such AFP pulse trains can enhance contrast between regions containing microscopic magnetic susceptibility variations and homogeneous regions in which dynamic dephasing relaxation mechanisms are dominant.
Robust quantum logic in neutral atoms via adiabatic Rydberg dressing
Keating, Tyler; Cook, Robert L.; Hankin, Aaron M.; Jau, Yuan -Yu; Biedermann, Grant W.; Deutsch, Ivan H.
2015-01-28
We study a scheme for implementing a controlled-Z (CZ) gate between two neutral-atom qubits based on the Rydberg blockade mechanism in a manner that is robust to errors caused by atomic motion. By employing adiabatic dressing of the ground electronic state, we can protect the gate from decoherence due to random phase errors that typically arise because of atomic thermal motion. In addition, the adiabatic protocol allows for a Doppler-free configuration that involves counterpropagating lasers in a σ+/σ- orthogonal polarization geometry that further reduces motional errors due to Doppler shifts. The residual motional error is dominated by dipole-dipole forces actingmore » on doubly-excited Rydberg atoms when the blockade is imperfect. As a result, for reasonable parameters, with qubits encoded into the clock states of 133Cs, we predict that our protocol could produce a CZ gate in < 10 μs with error probability on the order of 10-3.« less
AB INITIO SIMULATIONS FOR MATERIAL PROPERTIES ALONG THE JUPITER ADIABAT
French, Martin; Becker, Andreas; Lorenzen, Winfried; Nettelmann, Nadine; Bethkenhagen, Mandy; Redmer, Ronald; Wicht, Johannes
2012-09-15
We determine basic thermodynamic and transport properties of hydrogen-helium-water mixtures for the extreme conditions along Jupiter's adiabat via ab initio simulations, which are compiled in an accurate and consistent data set. In particular, we calculate the electrical and thermal conductivity, the shear and longitudinal viscosity, and diffusion coefficients of the nuclei. We present results for associated quantities like the magnetic and thermal diffusivity and the kinematic shear viscosity along an adiabat that is taken from a state-of-the-art interior structure model. Furthermore, the heat capacities, the thermal expansion coefficient, the isothermal compressibility, the Grueneisen parameter, and the speed of sound are calculated. We find that the onset of dissociation and ionization of hydrogen at about 0.9 Jupiter radii marks a region where the material properties change drastically. In the deep interior, where the electrons are degenerate, many of the material properties remain relatively constant. Our ab initio data will serve as a robust foundation for applications that require accurate knowledge of the material properties in Jupiter's interior, e.g., models for the dynamo generation.
The 0.1K bolometers cooled by adiabatic demagnetization
NASA Technical Reports Server (NTRS)
Roellig, T.; Lesyna, L.; Kittel, P.; Werner, M.
1983-01-01
The most straightforward way of reducing the noise equivalent power of bolometers is to lower their operating temperature. We have been exploring the possibility of using conventionally constructed bolometers at ultra-low temperatures to achieve NEP's suitable to the background environment of cooled space telescopes. We have chosen the technique of adiabatic demagnetization of a paramagnetic salt as a gravity independent, compact, and low power way to achieve temperatures below pumped He-3 (0.3 K). The demagnetization cryostat we used was capable of reaching temperatures below 0.08 K using Chromium Potassium Alum as a salt from a starting temperature of 1.5 K and a starting magnetic field of 30,000 gauss. Computer control of the magnetic field decay allowed a temperature of 0.2 K to be maintained to within 0.5 mK over a time period exceeding 14 hours. The refrigerator duty cycle was over 90 percent at this temperature. The success of these tests has motivated us to construct a more compact portable adiabatic demagnetization cryostat capable of bolometer optical tests and use at the 5m Hale telescope at 1mm wavelengths.
Sliding Seal Materials for Adiabatic Engines, Phase 2
NASA Technical Reports Server (NTRS)
Lankford, J.; Wei, W.
1986-01-01
An essential task in the development of the heavy-duty adiabatic diesel engine is identification and improvements of reliable, low-friction piston seal materials. In the present study, the sliding friction coefficients and wear rates of promising carbide, oxide, and nitride materials were measured under temperature, environmental, velocity, and loading conditions that are representative of the adiabatic engine environment. In addition, silicon nitride and partially stabilized zirconia disks were ion implanted with TiNi, Ni, Co, and Cr, and subsequently run against carbide pins, with the objective of producing reduced friction via solid lubrication at elevated temperature. In order to provide guidance needed to improve materials for this application, the program stressed fundamental understanding of the mechanisms involved in friction and wear. Electron microscopy was used to elucidate the micromechanisms of wear following wear testing, and Auger electron spectroscopy was used to evaluate interface/environment interactions which seemed to be important in the friction and wear process. Unmodified ceramic sliding couples were characterized at all temperatures by friction coefficients of 0.24 and above. The coefficient at 800 C in an oxidizing environment was reduced to below 0.1, for certain material combinations, by the ion implanation of TiNi or Co. This beneficial effect was found to derive from lubricious Ti, Ni, and Co oxides.
Turbulent Density Variations in Non-Adiabatic Interstellar Fluids
NASA Astrophysics Data System (ADS)
Higdon, J. C.; Conley, Alex
1998-05-01
Analyses of radio scintillation measurements have demonstrated (e.g., Rickett, ARAA, 28, 561, 1990) the existence of ubiquitous turbulent density fluctuations in the interstellar medium. Higdon (ApJ, 309, 342, 1986) and Goldreich and Sridhar (ApJ, 438, 763 1995) have modeled successfully these density variations as entropy structures distorted by convection in anisotropic magnetohydrodynamic turbulent flows. However, the interstellar medium is a heterogeneous non-adiabatic fluid whose thermal properties result ( Field, ApJ, 142, 531 1965) from a balance of heating and cooling rates. The effect of the non-adiabatic nature of interstellar fluids on the properties of turbulent cascades to small scales has not been considered previously. We find that in thermally stable fluids that the required balance of heating and cooling decreases the amplitudes of entropy structures independently of their spatial scale. Consequently, we show that if the time scale for turbulent flows to cascade to small scales is significantly greater than the cooling time of an interstellar fluid, the generation of turbulent denisty density variations at large wave numbers is greatly suppressed. Such results constrain possible values for the turbulent outer scale in models of interstellar turbulent flows.
Robust quantum logic in neutral atoms via adiabatic Rydberg dressing
Keating, Tyler; Cook, Robert L.; Hankin, Aaron M.; Jau, Yuan -Yu; Biedermann, Grant W.; Deutsch, Ivan H.
2015-01-28
We study a scheme for implementing a controlled-Z (CZ) gate between two neutral-atom qubits based on the Rydberg blockade mechanism in a manner that is robust to errors caused by atomic motion. By employing adiabatic dressing of the ground electronic state, we can protect the gate from decoherence due to random phase errors that typically arise because of atomic thermal motion. In addition, the adiabatic protocol allows for a Doppler-free configuration that involves counterpropagating lasers in a σ_{+}/σ_{-} orthogonal polarization geometry that further reduces motional errors due to Doppler shifts. The residual motional error is dominated by dipole-dipole forces acting on doubly-excited Rydberg atoms when the blockade is imperfect. As a result, for reasonable parameters, with qubits encoded into the clock states of ^{133}Cs, we predict that our protocol could produce a CZ gate in < 10 μs with error probability on the order of 10^{-3}.
Adiabatic cooling of the artificial Porcupine plasma jet
NASA Astrophysics Data System (ADS)
Ruizhin, Iu. Ia.; Treumann, R. A.; Bauer, O. H.; Moskalenko, A. M.
1987-01-01
Measurements of the plasma density obtained during the interaction of the artificial plasma jet, fired into the ionosphere with the body of the Porcupine main payload, have been analyzed for times when there was a well-developed wake effect. Using wake theory, the maximum temperature of the quasi-neutral xenon ion beam has been determined for an intermediate distance from the ion beam source when the beam has left the diamagnetic region but is still much denser than the ionospheric background plasma. The beam temperature is found to be about 4 times less than the temperature at injection. This observation is very well explained by adiabatic cooling of the beam during its initial diamagnetic and current-buildup phases at distances r smaller than 10 m. Outside this region, the beam conserves the temperature achieved. The observation proves that the artificial plasma jet passes through an initial gas-like diamagnetic phase restricted to the vicinity of the beam source, where it expands adiabatically. Partial cooling also takes place outside the diamagnetic region where the beam current still builds up. The observations also support a recently developed current-closure model of the quasi-neutral ion beam.
Temperature dependence of electronic eigenenergies in the adiabatic harmonic approximation
NASA Astrophysics Data System (ADS)
Poncé, S.; Antonius, G.; Gillet, Y.; Boulanger, P.; Laflamme Janssen, J.; Marini, A.; Côté, M.; Gonze, X.
2014-12-01
The renormalization of electronic eigenenergies due to electron-phonon interactions (temperature dependence and zero-point motion effect) is important in many materials. We address it in the adiabatic harmonic approximation, based on first principles (e.g., density-functional theory), from different points of view: directly from atomic position fluctuations or, alternatively, from Janak's theorem generalized to the case where the Helmholtz free energy, including the vibrational entropy, is used. We prove their equivalence, based on the usual form of Janak's theorem and on the dynamical equation. We then also place the Allen-Heine-Cardona (AHC) theory of the renormalization in a first-principles context. The AHC theory relies on the rigid-ion approximation, and naturally leads to a self-energy (Fan) contribution and a Debye-Waller contribution. Such a splitting can also be done for the complete harmonic adiabatic expression, in which the rigid-ion approximation is not required. A numerical study within the density-functional perturbation theory framework allows us to compare the AHC theory with frozen-phonon calculations, with or without the rigid-ion approximation. For the two different numerical approaches without non-rigid-ion terms, the agreement is better than 7 μ eV in the case of diamond, which represent an agreement to five significant digits. The magnitude of the non-rigid-ion terms in this case is also presented, distinguishing specific phonon modes contributions to different electronic eigenenergies.
FRW-type cosmologies with adiabatic matter creation
NASA Astrophysics Data System (ADS)
Lima, J. A. S.; Germano, A. S. M.; Abramo, L. R. W.
1996-04-01
Some properties of cosmological models with matter creation are investigated in the framework of the Friedmann-Robertson-Walker line element. For adiabatic matter creation, as developed by Prigogine and co-workers, we derive a simple expression relating the particle number density n and energy density ρ which holds regardless of the matter creation rate. The conditions to generate inflation are discussed and by considering the natural phenomenological matter creation rate ψ=3βnH, where β is a pure number of the order of unity and H is the Hubble parameter, a minimally modified hot big-bang model is proposed. The dynamic properties of such models can be deduced from the standard ones simply by replacing the adiabatic index γ of the equation of state by an effective parameter γ*=γ(1-β). The thermodynamic behavior is determined and it is also shown that ages large enough to agree with observations are obtained even given the high values of H suggested by recent measurements.
Adiabatic Processes Realized with a Trapped Brownian Particle
NASA Astrophysics Data System (ADS)
Martínez, Ignacio A.; Roldán, Édgar; Dinis, Luis; Petrov, Dmitri; Rica, Raúl A.
2015-03-01
The ability to implement adiabatic processes in the mesoscale is of key importance in the study of artificial or biological micro- and nanoengines. Microadiabatic processes have been elusive to experimental implementation due to the difficulty in isolating Brownian particles from their fluctuating environment. Here we report on the experimental realization of a microscopic quasistatic adiabatic process employing a trapped Brownian particle. We circumvent the complete isolation of the Brownian particle by designing a protocol where both characteristic volume and temperature of the system are changed in such a way that the entropy of the system is conserved along the process. We compare the protocols that follow from either the overdamped or underdamped descriptions, demonstrating that the latter is mandatory in order to obtain a vanishing average heat flux to the particle. We provide analytical expressions for the distributions of the fluctuating heat and entropy and verify them experimentally. Our protocols could serve to implement the first microscopic engine that is able to attain the fundamental limit for the efficiency set by Carnot.
Conditions for super-adiabatic droplet growth after entrainment mixing
Yang, Fan; Shaw, Raymond; Xue, Huiwen
2016-07-29
Cloud droplet response to entrainment and mixing between a cloud and its environment is considered, accounting for subsequent droplet growth during adiabatic ascent following a mixing event. The vertical profile for liquid water mixing ratio after a mixing event is derived analytically, allowing the reduction to be predicted from the mixing fraction and from the temperature and humidity for both the cloud and environment. It is derived for the limit of homogeneous mixing. The expression leads to a critical height above the mixing level: at the critical height the cloud droplet radius is the same for both mixed and unmixedmore » parcels, and the critical height is independent of the updraft velocity and mixing fraction. Cloud droplets in a mixed parcel are larger than in an unmixed parcel above the critical height, which we refer to as the “super-adiabatic” growth region. Analytical results are confirmed with a bin microphysics cloud model. Using the model, we explore the effects of updraft velocity, aerosol source in the environmental air, and polydisperse cloud droplets. Results show that the mixed parcel is more likely to reach the super-adiabatic growth region when the environmental air is humid and clean. It is also confirmed that the analytical predictions are matched by the volume-mean cloud droplet radius for polydisperse size distributions. The findings have implications for the origin of large cloud droplets that may contribute to onset of collision–coalescence in warm clouds.« less
High Energy Signatures of POST Adiabatic Supernova Remnants
NASA Astrophysics Data System (ADS)
Telezhinsky, Igor; Hnatyk, Bohdan
Between the well-known adiabatic and radiative stages of the Supernova remnant (SNR) evolution there is, in fact, a transition stage with a duration comparable to the duration of adiabatic one. Physical existence of the transition stage is motivated by cooling of some part of the downstream hot gas with formation of a thin cold shell that is joined to a shell of swept up interstellar medium (ISM). We give an approximate analytical method for full hydrodynamical description of the transition stage. On its base we investigate the evolution of X-ray and γ-ray radiation during this stage. It is shown that formation of a dense shell during the transition stage is accompanied by the decrease of X-ray luminosity because of hot gas cooling and increase of gamma-ray flux according to the increase of target proton density and CR energy in the newly born shell. The role of nonuniformity of ISM and its influence on the high energy fluxes from the SNRs is also discussed.
Breakdown of adiabatic electron behavior in expanding magnetic fields
NASA Astrophysics Data System (ADS)
Lichko, Emily; Egedal, Jan; Daughton, William
2015-11-01
During magnetic reconnection the incoming magnetic flux tubes expand in the inflow region. If this expansion is sufficiently slow the results are well described by a previously developed adiabatic model. Using kinetic simulations in a simple geometry and applying rapid magnetic perturbations, this study investigates the point at which the adiabatic assumption fails. To this end a 2D VPIC simulation was constructed, where the magnetic field in a uniform plasma is perturbed by externally driven currents. By varying the onset speed of the magnetic perturbation and the electron thermal speed, we found a sharp threshold at which this model breaks down. We believe that this point is determined by the time of the magnetic pumping compared to the electron transit time through the region, i.e. ω ~ Ḃ / B ~vthe / L . This threshold was also characterized by the launching of Whistler waves and with time domain structures, such as electron holes and double layers, which agree with those seen during magnetic reconnection and may relate to similar structures in the Van Allen Belts. NSF GEM award 1405166 and NASA grant NNX14AC68G.
Schedule path optimization for adiabatic quantum computing and optimization
NASA Astrophysics Data System (ADS)
Zeng, Lishan; Zhang, Jun; Sarovar, Mohan
2016-04-01
Adiabatic quantum computing and optimization have garnered much attention recently as possible models for achieving a quantum advantage over classical approaches to optimization and other special purpose computations. Both techniques are probabilistic in nature and the minimum gap between the ground state and first excited state of the system during evolution is a major factor in determining the success probability. In this work we investigate a strategy for increasing the minimum gap and success probability by introducing intermediate Hamiltonians that modify the evolution path between initial and final Hamiltonians. We focus on an optimization problem relevant to recent hardware implementations and present numerical evidence for the existence of a purely local intermediate Hamiltonian that achieve the optimum performance in terms of pushing the minimum gap to one of the end points of the evolution. As a part of this study we develop a convex optimization formulation of the search for optimal adiabatic schedules that makes this computation more tractable, and which may be of independent interest. We further study the effectiveness of random intermediate Hamiltonians on the minimum gap and success probability, and empirically find that random Hamiltonians have a significant probability of increasing the success probability, but only by a modest amount.
Phobos: Observed bulk properties
NASA Astrophysics Data System (ADS)
Pätzold, Martin; Andert, Tom; Jacobson, Robert; Rosenblatt, Pascal; Dehant, Véronique
2014-11-01
This work is a review of the mass determinations of the Mars moon Phobos by spacecraft close flybys, by solving for the Martian gravity field and by the analysis of secular orbit perturbations. The absolute value and accuracy is sensitive on the knowledge and accuracy of the Phobos ephemeris, of the spacecraft orbit, other perturbing forces acting on the spacecraft and the resolution of the Martian gravity field besides the measurement accuracy of the radio tracking data. The mass value and its error improved from spacecraft mission to mission or from the modern analysis of “old” tracking data but these solutions depend on the accuracy of the ephemeris at the time of observation. The mass value seems to settle within the range of GMPh=(7.11±0.09)×10-4 km3 s-2 which covers almost all mass values from close flybys and “distant” encounters within its 3-σ error (1.5%). Using the volume value determined from MEX HRSC imaging, the bulk density is (1873±31) kg m-3 (3-σ error or 1.7%), a low value which suggests that Phobos is either highly porous, is composed partially of light material or both. The determination of the gravity coefficients C20 and C22 from the Mars Express 2010 close flyby does not allow to draw conclusion on the internal structure. The large errors do not distinguish whether Phobos is homogeneous or not. In view of theories of the Phobos' origin, one possibility is that Phobos is not a captured asteroid but accreted from a debris disk in Mars orbit as a second generation solar system object.
2011-01-03
Bulk Data Mover (BDM) is a high-level data transfer management tool. BDM handles the issue of large variance in file sizes and a big portion of small files by managing the file transfers with optimized transfer queue and concurrency management algorithms. For example, climate simulation data sets are characterized by large volume of files with extreme variance in file sizes. The BDN achieves high performance using a variety of techniques, including multi-thraded concurrent transfer connections,more » data channel caching, load balancing over multiple transfer servers, and storage i/o pre-fetching. Logging information from the BDM is collected and analyzed to study the effectiveness of the transfer management algorithms. The BDM can accept a request composed of multiple files or an entire directory. The request also contains the target site and directory where the replicated files will reside. If a directory is provided at the source, then the BDM will replicate the structure of the source directory at the target site. The BDM is capable of transferring multiple files concurrently as well as using parallel TCP streams. The optimal level of concurrency or parallel streams depends on the bandwidth capacity of the storage systems at both ends of the transfer as well as achievable bandwidth of the wide-area network. Hardware req.-PC, MAC, Multi-platform & Workstation; Software req.: Compile/version-Java 1.50_x or ablove; Type of files: source code, executable modules, installation instructions other, user guide; URL: http://sdm.lbl.gov/bdm/« less
Size effects of effective Young's modulus for periodic cellular materials
NASA Astrophysics Data System (ADS)
Dai, Gaoming; Zhang, Weihong
2009-08-01
With the wide demands of cellular materials applications in aerospace and civil engineering, research effort sacrificed for this type of materials attains nowadays a higher level than ever before. This paper is focused on the prediction methods of effective Young’s modulus for periodical cellular materials. Based on comprehensive studies of the existing homogenization method (HM), the G-A meso-mechanics method (G-A MMM) and the stretching energy method (SEM) that are unable to reflect the size effect, we propose the bending energy method (BEM) for the first time, and a comparative study of these four methods is further made to show the generality and the capability of capturing the size effect of the BEM method. Meanwhile, the underlying characteristics of each method and their relations are clarified. To do this, the detailed finite element computing and existing experimental results of hexagonal honeycombs from the literature are adopted as the standard of comparison for the above four methods. Stretch and bending models of periodical cellular materials are taken into account, respectively for the comparison of stretch and flexural displacements resulting from the above methods. We conclude that the BEM has the strong ability of both predicting the effective Young’s modulus and revealing the size effect. Such a method is also able to predict well the variations of structural displacements in terms of the cell size under stretching and bending loads including the non-monotonous variations for the hexagonal cell. On the contrary, other three methods can only predict the limited results whenever the cell size tends to be infinitely small.
Measurement of corneal tangent modulus using ultrasound indentation.
Wang, Li-Ke; Huang, Yan-Ping; Tian, Lei; Kee, Chea-Su; Zheng, Yong-Ping
2016-09-01
Biomechanical properties are potential information for the diagnosis of corneal pathologies. An ultrasound indentation probe consisting of a load cell and a miniature ultrasound transducer as indenter was developed to detect the force-indentation relationship of the cornea. The key idea was to utilize the ultrasound transducer to compress the cornea and to ultrasonically measure the corneal deformation with the eyeball overall displacement compensated. Twelve corneal silicone phantoms were fabricated with different stiffness for the validation of measurement with reference to an extension test. In addition, fifteen fresh porcine eyes were measured by the developed system in vitro. The tangent moduli of the corneal phantoms calculated using the ultrasound indentation data agreed well with the results from the tensile test of the corresponding phantom strips (R(2)=0.96). The mean tangent moduli of the porcine corneas measured by the proposed method were 0.089±0.026MPa at intraocular pressure (IOP) of 15mmHg and 0.220±0.053MPa at IOP of 30mmHg, respectively. The coefficient of variation (CV) and intraclass correlation coefficient (ICC) of tangent modulus were 14.4% and 0.765 at 15mmHg, and 8.6% and 0.870 at 30mmHg, respectively. The preliminary study showed that ultrasound indentation could be applied to the measurement of corneal tangent modulus with good repeatability and improved measurement accuracy compared to conventional surface displacement-based measurement method. The ultrasound indentation can be a potential tool for the corneal biomechanical properties measurement in vivo.
Elastic area compressibility modulus of red cell membrane.
Evans, E A; Waugh, R; Melnik, L
1976-01-01
Micropipette measurements of isotropic tension vs. area expansion in pre-swollen single human red cells gave a value of 288 +/- 50 SD dyn/cm for the elastic, area compressibility modulus of the total membrane at 25 degrees C. This elastic constant, characterizing the resistance to area expansion or compression, is about 4 X 10(4) times greater than the elastic modulus for shear rigidity; therefore, in situations where deformation of the membrane does not require large isotropic tensions (e.g., in passage through normal capillaries), the membrane can be treated by a simple constitutive relation for a two-dimensionally, incompressible material (i.e. fixed area). The tension was found to be linear and reversible for the range of area changes observed (within the experimental system resolution of 10%). The maximum fractional area expansion required to produce lysis was uniformly distributed between 2 and 4% with 3% average and 0.7% SD. By heating the cells to 50 degrees C, it appears that the structural matrix (responsible for the shear rigidity and most of the strength in isotropic tension) is disrupted and primarily the lipid bilayer resists lysis. Therefore, the relative contributions of the structural matrix and lipid bilayer to the elastic, area compressibility could be estimated. The maximum isotropic tension at 25 degrees C is 10-12 dyn/cm and at 50 degrees C is between 3 and 4 dyn/cm. From this data, the respective compressibilities are estimated at 193 dyn/cm and 95 dyn/cm for structural network and bilayer. The latter value correlates well with data on in vitro, monolayer surface pressure versus area curves at oil-water interfaces. Images FIGURE 2 PMID:1276386
First principle investigation of structural and electronic properties of bulk ZnSe
Khatta, Swati; Tripathi, S. K. Prakash, Satya
2015-08-28
Electronic and structural properties of ZnSe are investigated using plane-wave self-consistent field method within the framework of density functional theory. The pseudopotential method within the local density approximation is used for the exchange-correlation potential. The equilibrium lattice parameter, static bulk modulus and its pressure derivative are calculated. The electronic band structure, partial density of states and density of states are also obtained. The results are compared with available theoretical calculations and experimental results.
NASA Astrophysics Data System (ADS)
Blaise, A.; André, S.; Delobelle, P.; Meshaka, Y.; Cunat, C.
2016-04-01
Exact measurements of the rheological parameters of time-dependent materials are crucial to improve our understanding of their intimate relation to the internal bulk microstructure. Concerning solid polymers and the apparently simple determination of Young's modulus in tensile tests, international standards rely on basic protocols that are known to lead to erroneous values. This paper describes an approach allowing a correct measurement of the instantaneous elastic modulus of polymers by a tensile test. It is based on the use of an appropriate reduced model to describe the behavior of the material up to great strains, together with well-established principles of parameter estimation in engineering science. These principles are objective tools that are used to determine which parameters of a model can be correctly identified according to the informational content of a given data set. The assessment of the methodology and of the measurements is accomplished by comparing the results with those obtained from two other physical experiments, probing the material response at small temporal and length scales, namely, ultrasound measurements with excitation at 5 MHz and modulated nanoindentation tests over a few nanometers of amplitude.
Abou Neel, Ensanya A.; Salih, Vehid; Revell, Peter A.; Young, Anne M.
2012-01-01
The aim of this study was to investigate the effect of reactive mono- and tricalcium phosphate addition on the mechanical, surface free energy, degradation and cell compatibility properties of poly(lactide-co-propylene glycol-co-lactide) dimethacrylate (PPGLDMA) thin films. Dry composites containing up to 70 wt.% filler were in a flexible rubber state at body temperature. Filler addition increased the initial strength and Young’s modulus and reduced the elastic and permanent deformation under load. The polymer had high polar surface free energy, which might enable greater spread upon bone. This was significantly reduced by filler addition but not by water immersion for 7 days. The samples exhibited reduced water sorption and associated bulk degradation when compared with previous work with thicker samples. Their cell compatibility was also improved. Filler raised water sorption and degradation but improved cell proliferation. The materials are promising bone adhesive candidates for low-load-bearing areas. PMID:21884829
Abou Neel, Ensanya A; Salih, Vehid; Revell, Peter A; Young, Anne M
2012-01-01
The aim of this study was to investigate the effect of reactive mono- and tricalcium phosphate addition on the mechanical, surface free energy, degradation and cell compatibility properties of poly(lactide-co-propylene glycol-co-lactide) dimethacrylate (PPGLDMA) thin films. Dry composites containing up to 70 wt.% filler were in a flexible rubber state at body temperature. Filler addition increased the initial strength and Young's modulus and reduced the elastic and permanent deformation under load. The polymer had high polar surface free energy, which might enable greater spread upon bone. This was significantly reduced by filler addition but not by water immersion for 7 days. The samples exhibited reduced water sorption and associated bulk degradation when compared with previous work with thicker samples. Their cell compatibility was also improved. Filler raised water sorption and degradation but improved cell proliferation. The materials are promising bone adhesive candidates for low-load-bearing areas. PMID:21884829
Abou Neel, Ensanya A; Salih, Vehid; Revell, Peter A; Young, Anne M
2012-01-01
The aim of this study was to investigate the effect of reactive mono- and tricalcium phosphate addition on the mechanical, surface free energy, degradation and cell compatibility properties of poly(lactide-co-propylene glycol-co-lactide) dimethacrylate (PPGLDMA) thin films. Dry composites containing up to 70 wt.% filler were in a flexible rubber state at body temperature. Filler addition increased the initial strength and Young's modulus and reduced the elastic and permanent deformation under load. The polymer had high polar surface free energy, which might enable greater spread upon bone. This was significantly reduced by filler addition but not by water immersion for 7 days. The samples exhibited reduced water sorption and associated bulk degradation when compared with previous work with thicker samples. Their cell compatibility was also improved. Filler raised water sorption and degradation but improved cell proliferation. The materials are promising bone adhesive candidates for low-load-bearing areas.
Strength and flexibility of bulk high-T{sub c} superconductors.
Goretta, K. C.; Jiang, M.; Kupperman, D. S.; Lanagan, M. T.; Singh, J. P.; Vasanthamohan, N.; Hinks, D. G.; Mitchell, J. F.; Richardson, J. W., Jr.
1997-06-01
Strength, fracture toughness, and elastic modulus data for bulk high-temperature superconductors, commercial 99.9% Ag, and a 1.2 at.% Mg/Ag alloy have been collected. These data have been used to calculate fracture strains for bulk conductors. The calculations indicate that the superconducting cores of clad tapes should begin to fracture at strains below 0.2%. In addition, residual strains in Ag-clad (Bi,Pb)2Sr2Ca2Cu3Ox tapes have been measured by neutron diffraction. An explanation is offered for why many tapes appear to be able to tolerate large strains before exhibiting a reduction in current transport.
Worms under Pressure: Bulk Mechanical Properties of C. elegans Are Independent of the Cuticle
Gilpin, William; Uppaluri, Sravanti; Brangwynne, Clifford P.
2015-01-01
The mechanical properties of cells and tissues play a well-known role in physiology and disease. The model organism Caenorhabditis elegans exhibits mechanical properties that are still poorly understood, but are thought to be dominated by its collagen-rich outer cuticle. To our knowledge, we use a novel microfluidic technique to reveal that the worm responds linearly to low applied hydrostatic stress, exhibiting a volumetric compression with a bulk modulus, κ = 140 ± 20 kPa; applying negative pressures leads to volumetric expansion of the worm, with a similar bulk modulus. Surprisingly, however, we find that a variety of collagen mutants and pharmacological perturbations targeting the cuticle do not impact the bulk modulus. Moreover, the worm exhibits dramatic stiffening at higher stresses—behavior that is also independent of the cuticle. The stress-strain curves for all conditions can be scaled onto a master equation, suggesting that C. elegans exhibits a universal elastic response dominated by the mechanics of pressurized internal organs. PMID:25902429
On the adiabatic stability of solitons and the matching of conservation laws
NASA Astrophysics Data System (ADS)
Lochak, Pierre
1984-08-01
We derive a series of identities which generalize and simplify the results obtained for adiabatically modulated solitons in the case of perturbed specific integrable equations. It stresses the importance of the variational properties of the solitons, which make an adiabatic theorem plausible. A precise conjecture is made and its validity discussed from different points of view.
Shear Modulus for Nonisotropic, Open-Celled Foams Using a General Elongated Kelvin Foam Model
NASA Technical Reports Server (NTRS)
Sullivan, Roy M.; Ghosn, Louis J.
2008-01-01
An equation for the shear modulus for nonisotropic, open-celled foams in the plane transverse to the elongation (rise) direction is derived using an elongated Kelvin foam model with the most general geometric description. The shear modulus was found to be a function of the unit cell dimensions, the solid material properties, and the cell edge cross-section properties. The shear modulus equation reduces to the relation derived by others for isotropic foams when the unit cell is equiaxed.
Goldilocks models of higher-dimensional inflation (including modulus stabilization)
NASA Astrophysics Data System (ADS)
Burgess, C. P.; Enns, Jared J. H.; Hayman, Peter; Patil, Subodh P.
2016-08-01
We explore the mechanics of inflation within simplified extra-dimensional models involving an inflaton interacting with the Einstein-Maxwell system in two extra dimensions. The models are Goldilocks-like inasmuch as they are just complicated enough to include a mechanism to stabilize the extra-dimensional size (or modulus), yet simple enough to solve explicitly the full extra-dimensional field equations using only simple tools. The solutions are not restricted to the effective 4D regime with H ll mKK (the latter referring to the characteristic mass splitting of the Kaluza-Klein excitations) because the full extra-dimensional Einstein equations are solved. This allows an exploration of inflationary physics in a controlled calculational regime away from the usual four-dimensional lamp-post. The inclusion of modulus stabilization is important because experience with string models teaches that this is usually what makes models fail: stabilization energies easily dominate the shallow potentials required by slow roll and so open up directions to evolve that are steeper than those of the putative inflationary direction. We explore (numerically and analytically) three representative kinds of inflationary scenarios within this simple setup. In one the radion is trapped in an inflaton-dependent local minimum whose non-zero energy drives inflation. Inflation ends as this energy relaxes to zero when the inflaton finds its own minimum. The other two involve power-law scaling solutions during inflation. One of these is a dynamical attractor whose features are relatively insensitive to initial conditions but whose slow-roll parameters cannot be arbitrarily small; the other is not an attractor but can roll much more slowly, until eventually transitioning to the attractor. The scaling solutions can satisfy H > mKK, but when they do standard 4D fluctuation calculations need not apply. When in a 4D regime the solutions predict η simeq 0 and so r simeq 0.11 when ns simeq 0.96 and so
Differential geometric treewidth estimation in adiabatic quantum computation
NASA Astrophysics Data System (ADS)
Wang, Chi; Jonckheere, Edmond; Brun, Todd
2016-07-01
The D-Wave adiabatic quantum computing platform is designed to solve a particular class of problems—the Quadratic Unconstrained Binary Optimization (QUBO) problems. Due to the particular "Chimera" physical architecture of the D-Wave chip, the logical problem graph at hand needs an extra process called minor embedding in order to be solvable on the D-Wave architecture. The latter problem is itself NP-hard. In this paper, we propose a novel polynomial-time approximation to the closely related treewidth based on the differential geometric concept of Ollivier-Ricci curvature. The latter runs in polynomial time and thus could significantly reduce the overall complexity of determining whether a QUBO problem is minor embeddable, and thus solvable on the D-Wave architecture.
Quasi-adiabatic compression heating of selected foods
NASA Astrophysics Data System (ADS)
Landfeld, Ales; Strohalm, Jan; Halama, Radek; Houska, Milan
2011-03-01
The quasi-adiabatic temperature increase due to compression heating, during high-pressure (HP) processing (HPP), was studied using specially designed equipment. The temperature increase was evaluated as the difference in temperature, during compression, between atmospheric pressure and nominal pressure. The temperature was measured using a thermocouple in the center of a polyoxymethylene cup, which contained the sample. Fresh meat balls, pork meat pate, and tomato purée temperature increases were measured at three initial temperature levels between 40 and 80 °C. Nominal pressure was either 400 or 500 MPa. Results showed that the fat content had a positive effect on temperature increases. Empirical equations were developed to calculate the temperature increase during HPP at different initial temperatures for pressures of 400 and 500 MPa. This thermal effect data can be used for numerical modeling of temperature histories of foods during HP-assisted pasteurization or sterilization processes.
Optical waveguide device with an adiabatically-varying width
Watts; Michael R. , Nielson; Gregory N.
2011-05-10
Optical waveguide devices are disclosed which utilize an optical waveguide having a waveguide bend therein with a width that varies adiabatically between a minimum value and a maximum value of the width. One or more connecting members can be attached to the waveguide bend near the maximum value of the width thereof to support the waveguide bend or to supply electrical power to an impurity-doped region located within the waveguide bend near the maximum value of the width. The impurity-doped region can form an electrical heater or a semiconductor junction which can be activated with a voltage to provide a variable optical path length in the optical waveguide. The optical waveguide devices can be used to form a tunable interferometer (e.g. a Mach-Zehnder interferometer) which can be used for optical modulation or switching. The optical waveguide devices can also be used to form an optical delay line.
Planar prism spectrometer based on adiabatically connected waveguiding slabs
NASA Astrophysics Data System (ADS)
Civitci, F.; Hammer, M.; Hoekstra, H. J. W. M.
2016-04-01
The device principle of a prism-based on-chip spectrometer for TE polarization is introduced. The spectrometer exploits the modal dispersion in planar waveguides in a layout with slab regions having two different thicknesses of the guiding layer. The set-up uses parabolic mirrors, for the collimation of light of the input waveguide and focusing of the light to the receiver waveguides, which relies on total internal reflection at the interface between two such regions. These regions are connected adiabatically to prevent unwanted mode conversion and loss at the edges of the prism. The structure can be fabricated with two wet etching steps. The paper presents basic theory and a general approach for device optimization. The latter is illustrated with a numerical example assuming SiON technology.
Passive gas-gap heat switch for adiabatic demagnetization refrigerator
NASA Technical Reports Server (NTRS)
Shirron, Peter J. (Inventor); Di Pirro, Michael J. (Inventor)
2005-01-01
A passive gas-gap heat switch for use with a multi-stage continuous adiabatic demagnetization refrigerator (ADR). The passive gas-gap heat switch turns on automatically when the temperature of either side of the switch rises above a threshold value and turns off when the temperature on either side of the switch falls below this threshold value. One of the heat switches in this multistage process must be conductive in the 0.25? K to 0.3? K range. All of the heat switches must be capable of switching off in a short period of time (1-2 minutes), and when off to have a very low thermal conductance. This arrangement allows cyclic cooling cycles to be used without the need for separate heat switch controls.
Adiabatic Floquet model for the optical response in femtosecond filaments
NASA Astrophysics Data System (ADS)
Hofmann, Michael; Brée, Carsten
2016-10-01
The standard model of femtosecond filamentation is based on phenomenological assumptions which suggest that the ionization-induced carriers can be treated as a homogeneous, uncorrelated plasma according to the Drude model, while the nonlinear response of the bound carriers is responsible for the all-optical Kerr effect. Here, we demonstrate that the additional plasma generated at a multiphoton resonance dominates the saturation of the nonlinear refractive index. Since resonances are not captured by the standard model, we propose a modification of the latter in which ionization enhancements can be accounted for by an ionization rate obtained from non-Hermitian Floquet theory. In the adiabatic regime of long pulse envelopes, this augmented standard model is in excellent agreement with direct quantum mechanical simulations. Since our proposal maintains the structure of the standard model, it can be easily incorporated into existing codes for the numerical simulation of femtosecond filaments.
Adiabatic passage with spin locking in Tm3+:YAG
NASA Astrophysics Data System (ADS)
Pascual-Winter, M. F.; Tongning, R. C.; Lauro, R.; Louchet-Chauvet, A.; Chanelière, T.; Le Gouët, J.-L.
2012-08-01
In low-concentration Tm3+:YAG, we observe efficient adiabatic rapid passage (ARP) of thulium nuclear spin over flipping times much longer than T2. Efficient ARP with long flipping time has been observed in monoatomic solids for decades and has been analyzed in terms of spin temperature and of the thermodynamic equilibrium of a coupled spin ensemble. In low-concentration impurity-doped crystals the spin temperature concept may be questioned. A single spin model should be preferred since the impurity ions are weakly coupled together but interact with the numerous off-resonant matrix ions that originate the spin-spin relaxation. The experiment takes place in the context of quantum information investigation, involving impurity-doped crystals, spin hyperpolarization by optical pumping, and optical detection of the spin evolution.
Adiabatic invariants in stellar dynamics. 1: Basic concepts
NASA Technical Reports Server (NTRS)
Weinberg, Martin D.
1994-01-01
The adiabatic criterion, widely used in astronomical dynamics, is based on the harmonic oscillator. It asserts that the change in action under a slowly varying perturbation is exponentially small. Recent mathematical results that precisely define the conditions for invariance show that this model does not apply in general. In particular, a slowly varying perturbation may cause significant evolution stellar dynamical systems even if its time scale is longer than any internal orbital time scale. This additional 'heating' may have serious implications for the evolution of star clusters and dwarf galaxies which are subject to long-term environmental forces. The mathematical developments leading to these results are reviewed, and the conditions for applicability to and further implications for stellar systems are discussed. Companion papers present a computational method for a general time-dependent disturbance and detailed example.
Shortcut to Adiabaticity for an Anisotropic Gas Containing Quantum Defects.
Papoular, D J; Stringari, S
2015-07-10
We present a shortcut to adiabaticity (STA) protocol applicable to 3D unitary Fermi gases and 2D weakly interacting Bose gases containing defects such as vortices or solitons. Our protocol relies on a new class of exact scaling solutions in the presence of anisotropic time-dependent harmonic traps. It connects stationary states in initial and final traps having the same frequency ratios. The resulting scaling laws exhibit a universal form and also apply to the classical Boltzmann gas. The duration of the STA can be made very short so as to realize a quantum quench from one stationary state to another. When applied to an anisotropically trapped superfluid gas, the STA conserves the shape of the quantum defects hosted by the cloud, thereby acting like a perfect microscope, which sharply contrasts with their strong distortion occurring during the free expansion of the cloud.
Multiphoton Raman Atom Optics with Frequency-Swept Adiabatic Passage
NASA Astrophysics Data System (ADS)
Kotru, Krish; Butts, David; Kinast, Joseph; Stoner, Richard
2016-05-01
Light-pulse atom interferometry is a promising candidate for future inertial navigators, gravitational wave detectors, and measurements of fundamental physical constants. The sensitivity of this technique, however, is often limited by the small momentum separations created between interfering atom wave packets (typically ~ 2 ℏk) . We address this issue using light-pulse atom optics derived from stimulated Raman transitions and frequency-swept adiabatic rapid passage (ARP). In experiments, these Raman ARP atom optics have generated up to 30 ℏk photon recoil momenta in an acceleration-sensitive atom interferometer, thereby enhancing the phase shift per unit acceleration by a factor of 15. Since this approach forgoes evaporative cooling and velocity selection, it could enable large-area atom interferometry at higher data rates, while also lowering the atom shot-noise-limited measurement uncertainty.
Some properties of adiabatic blast waves in preexisting cavities
NASA Technical Reports Server (NTRS)
Cox, D. P.; Franco, J.
1981-01-01
Cox and Anderson (1982) have conducted an investigation regarding an adiabatic blast wave in a region of uniform density and finite external pressure. In connection with an application of the results of the investigation to a study of interstellar blast waves in the very hot, low-density matrix, it was found that it would be desirable to examine situations with a positive radial density gradient in the ambient medium. Information concerning such situations is needed to learn about the behavior of blast waves occurring within preexisting, presumably supernova-induced cavities in the interstellar mass distribution. The present investigation is concerned with the first steps of a study conducted to obtain the required information. A review is conducted of Sedov's (1959) similarity solutions for the dynamical structure of any explosion in a medium with negligible pressure and power law density dependence on radius.
Hydroxylamine nitrate self-catalytic kinetics study with adiabatic calorimetry.
Liu, Lijun; Wei, Chunyang; Guo, Yuyan; Rogers, William J; Sam Mannan, M
2009-03-15
Hydroxylamine nitrate (HAN) is an important member of the hydroxylamine compound family with applications that include equipment decontamination in the nuclear industry and aqueous or solid propellants. Due to its instability and autocatalytic behavior, HAN has been involved in several incidents at the Hanford and Savannah River Site (SRS) [Technical Report on Hydroxylamine Nitrate, US Department of Energy, 1998]. Much research has been conducted on HAN in different areas, such as combustion mechanism, decomposition mechanism, and runaway behavior. However, the autocatalytic decomposition behavior of HAN at runaway stage has not been fully addressed due to its highly exothermic and rapid decomposition behavior. This work is focused on extracting HAN autocatalytic kinetics and analyzing HAN critical behavior from adiabatic calorimetry measurements. A lumped autocatalytic kinetic model for HAN and associated model parameters are determined. Also the storage and handling critical conditions of diluted HAN solution without metal presence are quantified.
Controlled Rapid Adiabatic Passage in a V-Type System
NASA Astrophysics Data System (ADS)
Song, Yunheung; Lee, Han-Gyeol; Jo, Hanlae; Ahn, Jaewook
2016-05-01
In chirped rapid adiabatic passage (RAP), chirp sign determines the final state to which the complete population transfer (CPT) occurs in a three-level V-type system. In this study, we show that laser intensity can be alternatively used as a control means in RAP, when the laser pulse is chirped and of a spectral hole resonant to one of the excited states. We verified such excitation selectivity in the experiment performed as-shaped femtosecond laser pulses interacting with the lowest three levels (5S, 5 P1/2, and 5 P3/2) of atomic rubidium. The successful demonstration implies that this intensity-dependent RAP in conjunction with laser beam profile programming may allow excitation selectivity for atoms or ions arranged in space.
Nucleon-deuteron scattering using the adiabatic projection method
NASA Astrophysics Data System (ADS)
Elhatisari, Serdar; Lee, Dean; Meißner, Ulf-G.; Rupak, Gautam
2016-06-01
In this paper we discuss the adiabatic projection method, a general framework for scattering and reaction calculations on the lattice. We also introduce several new techniques developed to study nucleus-nucleus scattering and reactions on the lattice. We present technical details of the method for large-scale problems. To estimate the systematic errors of the calculations we consider simple two-particle scattering on the lattice. Then we benchmark the accuracy and efficiency of the numerical methods by applying these to calculate fermion-dimer scattering in lattice effective field theory with and without a long-range Coulomb potential. The fermion-dimer calculations correspond to neutron-deuteron and proton-deuteron scattering in the spin-quartet channel at leading order in the pionless effective field theory.
Vertical and adiabatic electronic excitations in biphenylene: A theoretical study
NASA Astrophysics Data System (ADS)
Beck, M. E.; Rebentisch, R.; Hohlneicher, G.; Fülscher, M. P.; Serrano-Andrés, L.; Roos, B. O.
1997-12-01
The low-lying singlet states of biphenylene have been studied using ab initio methods. Vertical excitation energies were calculated by multiconfigurational perturbation theory (CASPT2), starting from a complete active space self-consistent field (CASSCF) reference. The geometries of the most important low-lying excited states were individually optimized at the CASSCF level to study the difference between vertical and adiabatic excitations. Extended atomic natural orbital (ANO)-type basis sets were used to calculate state energies. Geometry optimizations were done with smaller ANO-type basis sets. Excitations from the ground state to the 1 1B3g and 1 1B2u excited singlet states lead to pronounced geometry changes which alter the bond alternation pattern. The theoretical results provide a solid basis for the assignment and interpretation of experimental spectra.
Properties of a two stage adiabatic demagnetization refrigerator
NASA Astrophysics Data System (ADS)
Fukuda, H.; Ueda, S.; Arai, R.; Li, J.; Saito, A. T.; Nakagome, H.; Numazawa, T.
2015-12-01
Currently, many space missions using cryogenic temperatures are being planned. In particular, high resolution sensors such as Transition Edge Sensors need very low temperatures, below 100 mK. It is well known that the adiabatic demagnetization refrigerator (ADR) is one of most useful tools for producing ultra-low temperatures in space because it is gravity independent. We studied a continuous ADR system consisting of 4 stages and demonstrated it could provide continuous temperatures around 100 mK. However, there was some heat leakage from the power leads which resulted in reduced cooling power. Our efforts to upgrade our ADR system are presented. We show the effect of using the HTS power leads and discuss a cascaded Carnot cycle consisting of 2 ADR units.
Perspective: Stimulated Raman adiabatic passage: The status after 25 years
NASA Astrophysics Data System (ADS)
Bergmann, Klaas; Vitanov, Nikolay V.; Shore, Bruce W.
2015-05-01
The first presentation of the STIRAP (stimulated Raman adiabatic passage) technique with proper theoretical foundation and convincing experimental data appeared 25 years ago, in the May 1st, 1990 issue of The Journal of Chemical Physics. By now, the STIRAP concept has been successfully applied in many different fields of physics, chemistry, and beyond. In this article, we comment briefly on the initial motivation of the work, namely, the study of reaction dynamics of vibrationally excited small molecules, and how this initial idea led to the documented success. We proceed by providing a brief discussion of the physics of STIRAP and how the method was developed over the years, before discussing a few examples from the amazingly wide range of applications which STIRAP now enjoys, with the aim to stimulate further use of the concept. Finally, we mention some promising future directions.
Adiabatic model and design of a translating field reversed configuration
Intrator, T. P.; Siemon, R. E.; Sieck, P. E.
2008-04-15
We apply an adiabatic evolution model to predict the behavior of a field reversed configuration (FRC) during decompression and translation, as well as during boundary compression. Semi-empirical scaling laws, which were developed and benchmarked primarily for collisionless FRCs, are expected to remain valid even for the collisional regime of FRX-L experiment. We use this approach to outline the design implications for FRX-L, the high density translated FRC experiment at Los Alamos National Laboratory. A conical theta coil is used to accelerate the FRC to the largest practical velocity so it can enter a mirror bounded compression region, where it must be a suitable target for a magnetized target fusion (MTF) implosion. FRX-L provides the physics basis for the integrated MTF plasma compression experiment at the Shiva-Star pulsed power facility at Kirtland Air Force Research Laboratory, where the FRC will be compressed inside a flux conserving cylindrical shell.
Differential geometric treewidth estimation in adiabatic quantum computation
NASA Astrophysics Data System (ADS)
Wang, Chi; Jonckheere, Edmond; Brun, Todd
2016-10-01
The D-Wave adiabatic quantum computing platform is designed to solve a particular class of problems—the Quadratic Unconstrained Binary Optimization (QUBO) problems. Due to the particular "Chimera" physical architecture of the D-Wave chip, the logical problem graph at hand needs an extra process called minor embedding in order to be solvable on the D-Wave architecture. The latter problem is itself NP-hard. In this paper, we propose a novel polynomial-time approximation to the closely related treewidth based on the differential geometric concept of Ollivier-Ricci curvature. The latter runs in polynomial time and thus could significantly reduce the overall complexity of determining whether a QUBO problem is minor embeddable, and thus solvable on the D-Wave architecture.
Shortcut to Adiabaticity for an Anisotropic Gas Containing Quantum Defects
NASA Astrophysics Data System (ADS)
Papoular, D. J.; Stringari, S.
2015-07-01
We present a shortcut to adiabaticity (STA) protocol applicable to 3D unitary Fermi gases and 2D weakly interacting Bose gases containing defects such as vortices or solitons. Our protocol relies on a new class of exact scaling solutions in the presence of anisotropic time-dependent harmonic traps. It connects stationary states in initial and final traps having the same frequency ratios. The resulting scaling laws exhibit a universal form and also apply to the classical Boltzmann gas. The duration of the STA can be made very short so as to realize a quantum quench from one stationary state to another. When applied to an anisotropically trapped superfluid gas, the STA conserves the shape of the quantum defects hosted by the cloud, thereby acting like a perfect microscope, which sharply contrasts with their strong distortion occurring during the free expansion of the cloud.
Adiabatic Hamiltonian deformation, linear response theory, and nonequilibrium molecular dynamics
Hoover, W.G.
1980-05-28
Although Hamiltonians of various kinds have previously been used to derive Green-Kubo relations for the transport coefficients, the particular choice described is uniquely related to thermodynamics. This nonequilibrium Hamiltonian formulation of fluid flow provides pedagogically simple routes to nonequilibrium fluxes and distribution functions, to theoretical understanding of long-time effects, and to new numerical methods for simulating systems far from equilibrium. The same methods are now being applied to solid-phase problems. At the relatively high frequencies used in the viscous fluid calculations described, solids typically behave elastically. Lower frequencies lead to the formation of dislocations and other defects, making it possible to study plastic flow. A property of the nonequilibrium equations of motion which might be profitably explored is their effective irreversibility. Because only a few particles are necessary to generate irreversible behavior, simulations using adiabatic deformations of the kind described here could perhaps elucidate the instability in the equations of motion responsible for irreversibility.
Adiabatic quantum-flux-parametron cell library adopting minimalist design
Takeuchi, Naoki; Yamanashi, Yuki; Yoshikawa, Nobuyuki
2015-05-07
We herein build an adiabatic quantum-flux-parametron (AQFP) cell library adopting minimalist design and a symmetric layout. In the proposed minimalist design, every logic cell is designed by arraying four types of building block cells: buffer, NOT, constant, and branch cells. Therefore, minimalist design enables us to effectively build and customize an AQFP cell library. The symmetric layout reduces unwanted parasitic magnetic coupling and ensures a large mutual inductance in an output transformer, which enables very long wiring between logic cells. We design and fabricate several logic circuits using the minimal AQFP cell library so as to test logic cells in the library. Moreover, we experimentally investigate the maximum wiring length between logic cells. Finally, we present an experimental demonstration of an 8-bit carry look-ahead adder designed using the minimal AQFP cell library and demonstrate that the proposed cell library is sufficiently robust to realize large-scale digital circuits.
Laser-nucleus interactions: The quasi-adiabatic regime
NASA Astrophysics Data System (ADS)
Pálffy, Adriana; Buss, Oliver; Hoefer, Axel; Weidenmüller, Hans A.
2015-10-01
The interaction between nuclei and a strong zeptosecond laser pulse with coherent MeV photons is investigated theoretically. We provide a first semiquantitative study of the quasi-adiabatic regime where the photon absorption rate is comparable to the nuclear equilibration rate. In that regime, multiple photon absorption leads to the formation of a compound nucleus in the so-far unexplored regime of excitation energies several hundred MeV above the yrast line. The temporal dynamics of the process is investigated by means of a set of master equations that account for dipole absorption, stimulated dipole emission, neutron decay, and induced fission in a chain of nuclei. That set is solved numerically by means of state-of-the-art matrix exponential methods also used in nuclear fuel burn-up and radioactivity transport calculations. Our quantitative estimates predict the excitation path and range of nuclei reached by neutron decay and provide relevant information for the layout of future experiments.
Comments on adiabatic modifications to plasma turbulence theory
Krommes, J.A.
1980-11-01
Catto earlier introduced an interesting and plausible modification of the usual resonance-broadening prescription for obtaining the nonlinear dielectric function. He argued reasonably that one should employ that prescription only for the nonadiabatic response, and that one should treat the adiabatic response essentially exactly. However, Misguich, in a recent Comment on Catto's work, found an apparent divergence in a form for the renormalized dielectric which he argued was equivalent to Catto's. Misguich was thus led to conclude that, at least for stationary turbulence, Catto's form was suspect, and that a more intricate renormalization might have to be used to obtain a sensible, convergent result. It is argued that this conclusion is incorrect, at least for the reasons Misguich gives.
Model of TPTC Stirling engine with adiabatic working spaces
NASA Astrophysics Data System (ADS)
Renfroe, D. A.; Counts, M.
1988-10-01
A Stirling engine incorporating a phase-changing component of the working fluid has been modeled with the assumption that the compression and expansion space are adiabatic, and that the heat exchanger consists of a cooler, regenerator, and heater of finite size where the fluid follows an idealized temperature profile. Differential equations for the rate of change of mass in any cell and pressure over the entire engine were derived from the energy, continuity, state equations, and Dalton's law. From the simultaneous solution of these equations, all of the information necessary for calculation of power output and efficiency were obtained. Comparison of the results from this model with previous studies shows that the advantage of adding a phase-changing component to the working fluid may have been overstated.
Model of TPTC stirling engine with adiabatic working spaces
Renfroe, D.A.; Counts, M.
1988-10-01
A Stirling engine incorporating a phase-changing component of the working fluid has been modeled with the assumption that the compression and expansion space are adiabatic, and that the heat exchanger consists of a cooler, regenerator, and heater of finite size where the fluid follows an idealized temperature profile. Differential equations for the rate of change of mass in any cell and pressure over the entire engine were derived from the energy, continuity, state equations, and Dalton's law. From the simultaneous solution of these equations, all of the information necessary for calculation of power output and efficiency were obtained. Comparison of the results from this model with previous studies shows that the advantage of adding a phase-changing component to the working fluid may have been overstated.
From Classical Nonlinear Integrable Systems to Quantum Shortcuts to Adiabaticity.
Okuyama, Manaka; Takahashi, Kazutaka
2016-08-12
Using shortcuts to adiabaticity, we solve the time-dependent Schrödinger equation that is reduced to a classical nonlinear integrable equation. For a given time-dependent Hamiltonian, the counterdiabatic term is introduced to prevent nonadiabatic transitions. Using the fact that the equation for the dynamical invariant is equivalent to the Lax equation in nonlinear integrable systems, we obtain the counterdiabatic term exactly. The counterdiabatic term is available when the corresponding Lax pair exists and the solvable systems are classified in a unified and systematic way. Multisoliton potentials obtained from the Korteweg-de Vries equation and isotropic XY spin chains from the Toda equations are studied in detail. PMID:27563938
Robust entanglement via optomechanical dark mode: adiabatic scheme
NASA Astrophysics Data System (ADS)
Tian, Lin; Wang, Ying-Dan; Huang, Sumei; Clerk, Aashish
2013-03-01
Entanglement is a powerful resource for studying quantum effects in macroscopic objects and for quantum information processing. Here, we show that robust entanglement between cavity modes with distinct frequencies can be generated via a mechanical dark mode in an optomechanical quantum interface. Due to quantum interference, the effect of the mechanical noise is cancelled in a way that is similar to the electromagnetically induced transparency. We derive the entanglement in the strong coupling regime by solving the quantum Langevin equation using a perturbation theory approach. The entanglement in the adiabatic scheme is then compared with the entanglement in the stationary state scheme. Given the robust entanglement schemes and our previous schemes on quantum wave length conversion, the optomechanical interface hence forms an effective building block for a quantum network. This work is supported by DARPA-ORCHID program, NSF-DMR-0956064, NSF-CCF-0916303, and NSF-COINS.
Shortcut to Adiabaticity for an Anisotropic Gas Containing Quantum Defects.
Papoular, D J; Stringari, S
2015-07-10
We present a shortcut to adiabaticity (STA) protocol applicable to 3D unitary Fermi gases and 2D weakly interacting Bose gases containing defects such as vortices or solitons. Our protocol relies on a new class of exact scaling solutions in the presence of anisotropic time-dependent harmonic traps. It connects stationary states in initial and final traps having the same frequency ratios. The resulting scaling laws exhibit a universal form and also apply to the classical Boltzmann gas. The duration of the STA can be made very short so as to realize a quantum quench from one stationary state to another. When applied to an anisotropically trapped superfluid gas, the STA conserves the shape of the quantum defects hosted by the cloud, thereby acting like a perfect microscope, which sharply contrasts with their strong distortion occurring during the free expansion of the cloud. PMID:26207476
Novel latch for adiabatic quantum-flux-parametron logic
Takeuchi, Naoki Yamanashi, Yuki; Yoshikawa, Nobuyuki; Ortlepp, Thomas
2014-03-14
We herein propose the quantum-flux-latch (QFL) as a novel latch for adiabatic quantum-flux-parametron (AQFP) logic. A QFL is very compact and compatible with AQFP logic gates and can be read out in one clock cycle. Simulation results revealed that the QFL operates at 5 GHz with wide parameter margins of more than ±22%. The calculated energy dissipation was only ∼0.1 aJ/bit, which yields a small energy delay product of 20 aJ·ps. We also designed shift registers using QFLs to demonstrate more complex circuits with QFLs. Finally, we experimentally demonstrated correct operations of the QFL and a 1-bit shift register (a D flip-flop)
Pitch-angle scattering of energetic particles with adiabatic focusing
Tautz, R. C.; Shalchi, A.; Dosch, A. E-mail: andreasm4@yahoo.com
2014-10-20
Understanding turbulent transport of charged particles in magnetized plasmas often requires a model for the description of random variations in the particle's pitch angle. The Fokker-Planck coefficient of pitch-angle scattering, which is used to describe scattering parallel to the mean magnetic field, is therefore of central importance. Whereas quasi-linear theory assumes a homogeneous mean magnetic field, such a condition is often not fulfilled, especially for high-energy particles. Here, a new derivation of the quasi-linear approach is given that is based on the unperturbed orbit found for an adiabatically focused mean magnetic field. The results show that, depending on the ratio of the focusing length and the particle's Larmor radius, the Fokker-Planck coefficient is significantly modified but agrees with the classical expression in the limit of a homogeneous mean magnetic field.
New Dynamical Scaling Universality for Quantum Networks Across Adiabatic Quantum Phase Transitions
NASA Astrophysics Data System (ADS)
Acevedo, Oscar L.; Rodriguez, Ferney J.; Quiroga, Luis; Johnson, Neil F.; Rey, Ana M.
2014-05-01
We reveal universal dynamical scaling behavior across adiabatic quantum phase transitions in networks ranging from traditional spatial systems (Ising model) to fully connected ones (Dicke and Lipkin-Meshkov-Glick models). Our findings, which lie beyond traditional critical exponent analysis and adiabatic perturbation approximations, are applicable even where excitations have not yet stabilized and, hence, provide a time-resolved understanding of quantum phase transitions encompassing a wide range of adiabatic regimes. We show explicitly that even though two systems may traditionally belong to the same universality class, they can have very different adiabatic evolutions. This implies that more stringent conditions need to be imposed than at present, both for quantum simulations where one system is used to simulate the other and for adiabatic quantum computing schemes.
New Dynamical Scaling Universality for Quantum Networks Across Adiabatic Quantum Phase Transitions
NASA Astrophysics Data System (ADS)
Acevedo, O. L.; Quiroga, L.; Rodríguez, F. J.; Johnson, N. F.
2014-01-01
We reveal universal dynamical scaling behavior across adiabatic quantum phase transitions in networks ranging from traditional spatial systems (Ising model) to fully connected ones (Dicke and Lipkin-Meshkov-Glick models). Our findings, which lie beyond traditional critical exponent analysis and adiabatic perturbation approximations, are applicable even where excitations have not yet stabilized and, hence, provide a time-resolved understanding of quantum phase transitions encompassing a wide range of adiabatic regimes. We show explicitly that even though two systems may traditionally belong to the same universality class, they can have very different adiabatic evolutions. This implies that more stringent conditions need to be imposed than at present, both for quantum simulations where one system is used to simulate the other and for adiabatic quantum computing schemes.
Stimulated Raman adiabatic passage in a three-level superconducting circuit
NASA Astrophysics Data System (ADS)
Kumar, K. S.; Vepsäläinen, A.; Danilin, S.; Paraoanu, G. S.
2016-02-01
The adiabatic manipulation of quantum states is a powerful technique that opened up new directions in quantum engineering--enabling tests of fundamental concepts such as geometrical phases and topological transitions, and holding the promise of alternative models of quantum computation. Here we benchmark the stimulated Raman adiabatic passage for circuit quantum electrodynamics by employing the first three levels of a transmon qubit. In this ladder configuration, we demonstrate a population transfer efficiency >80% between the ground state and the second excited state using two adiabatic Gaussian-shaped control microwave pulses. By doing quantum tomography at successive moments during the Raman pulses, we investigate the transfer of the population in time domain. Furthermore, we show that this protocol can be reversed by applying a third adiabatic pulse, we study a hybrid nondiabatic-adiabatic sequence, and we present experimental results for a quasi-degenerate intermediate level.
Stimulated Raman adiabatic passage in a three-level superconducting circuit.
Kumar, K S; Vepsäläinen, A; Danilin, S; Paraoanu, G S
2016-01-01
The adiabatic manipulation of quantum states is a powerful technique that opened up new directions in quantum engineering--enabling tests of fundamental concepts such as geometrical phases and topological transitions, and holding the promise of alternative models of quantum computation. Here we benchmark the stimulated Raman adiabatic passage for circuit quantum electrodynamics by employing the first three levels of a transmon qubit. In this ladder configuration, we demonstrate a population transfer efficiency >80% between the ground state and the second excited state using two adiabatic Gaussian-shaped control microwave pulses. By doing quantum tomography at successive moments during the Raman pulses, we investigate the transfer of the population in time domain. Furthermore, we show that this protocol can be reversed by applying a third adiabatic pulse, we study a hybrid nondiabatic-adiabatic sequence, and we present experimental results for a quasi-degenerate intermediate level. PMID:26902454
Elastic shear modulus: Fits to data and extrapolation to large compressions and negative pressure
Straub, G.K.
1990-12-01
An analytic form for the elastic shear modulus is presented and its fit to data at different compressions is demonstrated for copper and tungsten. When only shear modulus at zero pressure and its logarithmic derivative are known, an approximate procedure is used to generate the parameters for an analytic form for the shear modulus. This procedure is demonstrated, and estimates are provided of the shear modulus as a function of compression, for Al, Cu, Fe, Mo, W, Ta, and U. 5 refs., 3 figs., 3 tabs.
Generic relation between the electron work function and Young's modulus of metals
Hua Guomin; Li Dongyang
2011-07-25
In this study, efforts were made to establish a generic relation between the Young's modulus and the electron work function of polycrystalline metals, in which Young's Modulus was defined as the second order derivative of interaction potential with respect to the equilibrium distance. The obtained Young's modulus shows a sextic relation with the work function. Data of Young's modulus and work function of polycrystalline metals, including Alkali earth metals, transition metals, and rare earth metals, can be fitted reasonably well by this derived generic relationship.
Elastic modulus of supercooled liquid and hot solid silicon measured by inelastic X-ray scattering
Alatas, A.; Said, A. H.; Sinn, H.; Alp, E. E.; Kodituwakku, C. N.; Reinhart, B.; Saboungi, M. -L.; Price, D. L.
2005-12-01
We measured the dynamical structure factors of supercooled-liquid and hot-solid silicon by inelastic X-ray scattering at the same temperature, 1620 K. Two significant changes in the averaged longitudinal sound velocities and in the longitudinal modulus are observed. We, first observe a different longitudinal modulus in the polycrystalline hot-solid silicon compared to the extrapolated value obtained from the single-crystal measurement. Furthermore, this reduction of the modulus may be a precursor of the semiconductor-to-metal transition. Second, the increase in the longitudinal modulus in the liquid upon supercooling is consistent with an increase in the degree of the directional bonding.
Wigner phase space distribution via classical adiabatic switching
Bose, Amartya; Makri, Nancy
2015-09-21
Evaluation of the Wigner phase space density for systems of many degrees of freedom presents an extremely demanding task because of the oscillatory nature of the Fourier-type integral. We propose a simple and efficient, approximate procedure for generating the Wigner distribution that avoids the computational difficulties associated with the Wigner transform. Starting from a suitable zeroth-order Hamiltonian, for which the Wigner density is available (either analytically or numerically), the phase space distribution is propagated in time via classical trajectories, while the perturbation is gradually switched on. According to the classical adiabatic theorem, each trajectory maintains a constant action if the perturbation is switched on infinitely slowly. We show that the adiabatic switching procedure produces the exact Wigner density for harmonic oscillator eigenstates and also for eigenstates of anharmonic Hamiltonians within the Wentzel-Kramers-Brillouin (WKB) approximation. We generalize the approach to finite temperature by introducing a density rescaling factor that depends on the energy of each trajectory. Time-dependent properties are obtained simply by continuing the integration of each trajectory under the full target Hamiltonian. Further, by construction, the generated approximate Wigner distribution is invariant under classical propagation, and thus, thermodynamic properties are strictly preserved. Numerical tests on one-dimensional and dissipative systems indicate that the method produces results in very good agreement with those obtained by full quantum mechanical methods over a wide temperature range. The method is simple and efficient, as it requires no input besides the force fields required for classical trajectory integration, and is ideal for use in quasiclassical trajectory calculations.
Phase relations and adiabats in boiling seafloor geothermal systems
Bischoff, J.L.; Pitzer, Kenneth S.
1985-01-01
Observations of large salinity variations and vent temperatures in the range of 380-400??C suggest that boiling or two-phase separation may be occurring in some seafloor geothermal systems. Consideration of flow rates and the relatively small differences in density between vapors and liquids at the supercritical pressures at depth in these systems suggests that boiling is occurring under closed-system conditions. Salinity and temperature of boiling vents can be used to estimate the pressure-temperature point in the subsurface at which liquid seawater first reached the two-phase boundary. Data are reviewed to construct phase diagrams of coexisting brines and vapors in the two-phase region at pressures corresponding to those of the seafloor geothermal systems. A method is developed for calculating the enthalpy and entropy of the coexisting mixtures, and results are used to construct adiabats from the seafloor to the P-T two-phase boundary. Results for seafloor vents discharging at 2300 m below sea level indicate that a 385??C vent is composed of a brine (7% NaCl equivalent) in equilibrium with a vapor (0.1% NaCl). Brine constitutes 45% by weight of the mixture, and the fluid first boiled at approximately 1 km below the seafloor at 415??C, 330 bar. A 400??C vent is primarily vapor (88 wt.%, 0.044% NaCl) with a small amount of brine (26% NaCl) and first boiled at 2.9 km below the seafloor at 500??C, 520 bar. These results show that adiabatic decompression in the two-phase region results in dramatic cooling of the fluid mixture when there is a large fraction of vapor. ?? 1985.
Many-body effects on adiabatic passage through Feshbach resonances
NASA Astrophysics Data System (ADS)
Tikhonenkov, I.; Pazy, E.; Band, Y. B.; Fleischhauer, M.; Vardi, A.
2006-04-01
We theoretically study the dynamics of an adiabatic sweep through a Feshbach resonance, thereby converting a degenerate quantum gas of fermionic atoms into a degenerate quantum gas of bosonic dimers. Our analysis relies on a zero temperature mean-field theory which accurately accounts for initial molecular quantum fluctuations, triggering the association process. The structure of the resulting semiclassical phase space is investigated, highlighting the dynamical instability of the system towards association, for sufficiently small detuning from resonance. It is shown that this instability significantly modifies the finite-rate efficiency of the sweep, transforming the single-pair exponential Landau-Zener behavior of the remnant fraction of atoms Γ on sweep rate α , into a power-law dependence as the number of atoms increases. The obtained nonadiabaticity is determined from the interplay of characteristic time scales for the motion of adiabatic eigenstates and for fast periodic motion around them. Critical slowing-down of these precessions near the instability leads to the power-law dependence. A linear power law Γ∝α is obtained when the initial molecular fraction is smaller than the 1/N quantum fluctuations, and a cubic-root power law Γ∝α1/3 is attained when it is larger. Our mean-field analysis is confirmed by exact calculations, using Fock-space expansions. Finally, we fit experimental low temperature Feshbach sweep data with a power-law dependence. While the agreement with the experimental data is well within experimental error bars, similar accuracy can be obtained with an exponential fit, making additional data highly desirable.
Many-body effects on adiabatic passage through Feshbach resonances
Tikhonenkov, I.; Pazy, E.; Band, Y. B.; Vardi, A.; Fleischhauer, M.
2006-04-15
We theoretically study the dynamics of an adiabatic sweep through a Feshbach resonance, thereby converting a degenerate quantum gas of fermionic atoms into a degenerate quantum gas of bosonic dimers. Our analysis relies on a zero temperature mean-field theory which accurately accounts for initial molecular quantum fluctuations, triggering the association process. The structure of the resulting semiclassical phase space is investigated, highlighting the dynamical instability of the system towards association, for sufficiently small detuning from resonance. It is shown that this instability significantly modifies the finite-rate efficiency of the sweep, transforming the single-pair exponential Landau-Zener behavior of the remnant fraction of atoms {gamma} on sweep rate {alpha}, into a power-law dependence as the number of atoms increases. The obtained nonadiabaticity is determined from the interplay of characteristic time scales for the motion of adiabatic eigenstates and for fast periodic motion around them. Critical slowing-down of these precessions near the instability leads to the power-law dependence. A linear power law {gamma}{proportional_to}{alpha} is obtained when the initial molecular fraction is smaller than the 1/N quantum fluctuations, and a cubic-root power law {gamma}{proportional_to}{alpha}{sup 1/3} is attained when it is larger. Our mean-field analysis is confirmed by exact calculations, using Fock-space expansions. Finally, we fit experimental low temperature Feshbach sweep data with a power-law dependence. While the agreement with the experimental data is well within experimental error bars, similar accuracy can be obtained with an exponential fit, making additional data highly desirable.
Observational tests of non-adiabatic Chaplygin gas
Carneiro, S.; Pigozzo, C. E-mail: cpigozzo@ufba.br
2014-10-01
In a previous paper [1] it was shown that any dark sector model can be mapped into a non-adiabatic fluid formed by two interacting components, one with zero pressure and the other with equation-of-state parameter ω = -1. It was also shown that the latter does not cluster and, hence, the former is identified as the observed clustering matter. This guarantees that the dark matter power spectrum does not suffer from oscillations or instabilities. It applies in particular to the generalised Chaplygin gas, which was shown to be equivalent to interacting models at both background and perturbation levels. In the present paper we test the non-adiabatic Chaplygin gas against the Hubble diagram of type Ia supernovae, the position of the first acoustic peak in the anisotropy spectrum of the cosmic microwave background and the linear power spectrum of large scale structures. We consider two different compilations of SNe Ia, namely the Constitution and SDSS samples, both calibrated with the MLCS2k2 fitter, and for the power spectrum we use the 2dFGRS catalogue. The model parameters to be adjusted are the present Hubble parameter, the present matter density and the Chaplygin gas parameter α. The joint analysis best fit gives α ≈ - 0.5, which corresponds to a constant-rate energy flux from dark energy to dark matter, with the dark energy density decaying linearly with the Hubble parameter. The ΛCDM model, equivalent to α = 0, stands outside the 3σ confidence interval.
Decoherence and adiabatic transport in semiconductor quantum dots
NASA Astrophysics Data System (ADS)
Switkes, Michael
2000-10-01
I present research on ballistic electron transport in lateral GaAs/AlGaAs quantum dots connected to the environment with leads supporting one or more fully transmitting quantum modes. The first part of this dissertation examines electron the phenomena which mediate the transition from quantum mechanical to classical behavior in these quantum dots. Measurements of electron phase coherence time based on the magnitude of weak localization correction are presented as a function both of temperature and of applied bias. The coherence time is found to depend on temperature approximately as a sum of two power laws, tauφ ≈ AT-1 + BT-2, in agreement with the prediction for diffusive two dimensional systems but not with predictions for closed quantum dots or ballistic 2D systems. The effects of a large applied bias can be described with an elevated effective electron temperature calculated from the balance of Joule heating and cooling by Wiedemann-Franz out diffusion of hot electrons. The limits this imposes for quantum dot based technologies are examined through the detailed analysis of a quantum dot magnetometer. The second part of the work presented here focuses on a novel form of electron transport, adiabatic quantum electron pumping, in which a current is driven by cyclic changes in the wave function of a mesoscopic system rather than by an externally imposed bias. After a brief review of other mechanisms which produce a dc current from an ac excitation, measurements of adiabatic pumping are presented. The pumped current (or voltage) is sinusoidal in the phase difference between the two ac voltages deforming the dot potential and fluctuates in both magnitude and direction with small changes in external parameters such as magnetic field. Dependencies of pumping on the strength of the deformations, temperature, and breaking of time-reversal symmetry are also investigated.
Dentinogenesis imperfecta - hardness and Young's modulus of teeth.
Wieczorek, Aneta; Loster, Jolanta; Ryniewicz, Wojciech; Ryniewicz, Anna M
2013-01-01
Dentinogenesis imperfecta type II (DI-II) is the most common dental genetic disease with reported incidence 1 in 8000. Elasticity and hardness of the enamel of teeth are important values which are connected with their resistance to attrition. It is hypothesized that values of physical properties for healthy teeth and teeth with DI-II are different. The aim of the study was to investigate some physical properties of teeth extracted from patients with DI-II in comparison with normal teeth. The material of the study was six teeth: three lower molars, with clinical signs of DI-II, which were extracted due to complications of pulp inflammation and three other lower molars which were extracted for orthodontic reasons - well formed, without any signs of pathology. The surfaces of DI-II and normal teeth were tested on the CSM Instruments Scratch Tester machine (producer CSEM Switzerland) by Oliver and Pharr method. The indenter used was Vicker's VG-73 diamond indenter. Additionally, the Scanning Electron Microscopy (SEM) analysis of the surface of the teeth with DI-II was made. Vickers hardness of the teeth with dental pathology (DI-II) was seven times smaller, and Young's modulus six times smaller than those of healthy teeth. The parameters of hardness and elasticity of enamel of teeth with clinical diagnosis of DI-II were very much smaller than in normal teeth and because of that can be responsible for attrition.
Impedance and modulus spectroscopic study of nano hydroxyapatite
NASA Astrophysics Data System (ADS)
Jogiya, B. V.; Jethava, H. O.; Tank, K. P.; Raviya, V. R.; Joshi, M. J.
2016-05-01
Hydroxyapatite (Ca10 (PO4)6 (OH)2, HAP) is the main inorganic component of the hard tissues in bones and also important material for orthopedic and dental implant applications. Nano HAP is of great interest due to its various bio-medical applications. In the present work the nano HAP was synthesized by using surfactant mediated approach. Structure and morphology of the synthesized nano HAP was examined by the Powder XRD and TEM. Impedance study was carried out on pelletized sample in a frequency range of 100Hz to 20MHz at room temperature. The variation of dielectric constant, dielectric loss, and a.c. conductivity with frequency of applied field was studied. The Nyquist plot as well as modulus plot was drawn. The Nyquist plot showed two semicircle arcs, which indicated the presence of grain and grain boundary effect in the sample. The typical behavior of the Nyquist plot was represented by equivalent circuit having two parallel RC combinations in series.
Short Exon Detection via Wavelet Transform Modulus Maxima
Zhang, Xiaolei; Shen, Zhiwei; Zhang, Guishan; Shen, Yuanyu; Chen, Miaomiao; Zhao, Jiaxiang; Wu, Renhua
2016-01-01
The detection of short exons is a challenging open problem in the field of bioinformatics. Due to the fact that the weakness of existing model-independent methods lies in their inability to reliably detect small exons, a model-independent method based on the singularity detection with wavelet transform modulus maxima has been developed for detecting short coding sequences (exons) in eukaryotic DNA sequences. In the analysis of our method, the local maxima can capture and characterize singularities of short exons, which helps to yield significant patterns that are rarely observed with the traditional methods. In order to get some information about singularities on the differences between the exon signal and the background noise, the noise level is estimated by filtering the genomic sequence through a notch filter. Meanwhile, a fast method based on a piecewise cubic Hermite interpolating polynomial is applied to reconstruct the wavelet coefficients for improving the computational efficiency. In addition, the output measure of a paired-numerical representation calculated in both forward and reverse directions is used to incorporate a useful DNA structural property. The performances of our approach and other techniques are evaluated on two benchmark data sets. Experimental results demonstrate that the proposed method outperforms all assessed model-independent methods for detecting short exons in terms of evaluation metrics. PMID:27635656
Application of diffusion barriers to high modulus fibers
NASA Technical Reports Server (NTRS)
Veltri, R. D.; Douglas, F. C.; Paradis, E. L.; Galasso, F. S.
1977-01-01
Barrier layers were coated onto high-modulus fibers, and nickel and titanium layers were overcoated as simulated matrix materials. The objective was to coat the high-strength fibers with unreactive selected materials without degrading the fibers. The fibers were tungsten, niobium, and single-crystal sapphire, while the materials used as barrier coating layers were Al2O3, Y2O3, TiC, ZrC, WC with 14% Co, and HfO2. An ion-plating technique was used to coat the fibers. The fibers were subjected to high-temperature heat treatments to evaluate the effectiveness of the barrier layer in preventing fiber-metal interactions. Results indicate that Al2O3, Y2O3, and HfO2 can be used as barrier layers to minimize the nickel-tungsten interaction. Further investigation, including thermal cycling tests at 1090 C, revealed that HfO2 is probably the best of the three.
Dangling chain effect on the modulus of polyurethane networks
NASA Astrophysics Data System (ADS)
Fayolle, Bruno; Diani, Julie; Gilormini, Pierre
2008-03-01
While the theory of elasticity has been well verified for the non ideal structures accounting for contribution of entanglements, some effort is needed to investigate the contribution of dangling chains. In order to establish a quantitative contribution of dangling chains, networks with a controlled architecture, i.e. where architecture is determined by synthesis of well-characterized reactants, are required. In this work, polyurethane networks based on poly(propylether) and poly(tetramethyl adipate) crosslinked by triisocyanate were prepared and studied. Different polyether molar masses are chosen from 430 g/mol up to 4000 g/mol. By varying the stoechiometric ratio r = [NCO]/[OH] between 0.4 and 1, dangling chains are introduced, provided that the reaction between NCO groups is negligible. After synthesis, the Young's modulus (E) of the networks has been measured from tensile tests according to the neo-Hookean law. The molar mass of elastically active network chains (ENAC) is determined from E. Since this molar mass is close to the molar mass of each diol used for synthesis at r=1 (``ideal'' network), a correction taking into account the number of dangling chains (b) calculated from r is proposed.
Short Exon Detection via Wavelet Transform Modulus Maxima.
Zhang, Xiaolei; Shen, Zhiwei; Zhang, Guishan; Shen, Yuanyu; Chen, Miaomiao; Zhao, Jiaxiang; Wu, Renhua
2016-01-01
The detection of short exons is a challenging open problem in the field of bioinformatics. Due to the fact that the weakness of existing model-independent methods lies in their inability to reliably detect small exons, a model-independent method based on the singularity detection with wavelet transform modulus maxima has been developed for detecting short coding sequences (exons) in eukaryotic DNA sequences. In the analysis of our method, the local maxima can capture and characterize singularities of short exons, which helps to yield significant patterns that are rarely observed with the traditional methods. In order to get some information about singularities on the differences between the exon signal and the background noise, the noise level is estimated by filtering the genomic sequence through a notch filter. Meanwhile, a fast method based on a piecewise cubic Hermite interpolating polynomial is applied to reconstruct the wavelet coefficients for improving the computational efficiency. In addition, the output measure of a paired-numerical representation calculated in both forward and reverse directions is used to incorporate a useful DNA structural property. The performances of our approach and other techniques are evaluated on two benchmark data sets. Experimental results demonstrate that the proposed method outperforms all assessed model-independent methods for detecting short exons in terms of evaluation metrics. PMID:27635656
Rolling, slip and traction measurements on low modulus materials
NASA Technical Reports Server (NTRS)
Tevaarwerk, J. L.
1985-01-01
Traction and wear tests were performed on six low modulus materials (LMM). Three different traction tests were performed to determine the suitability of the material for use as traction rollers. These were the rolling, slip and endurance traction tests. For each material the combination LMM on LMM and LMM on steel were evaluated. Rolling traction test were conducted to determine the load - velocity limits, the rolling traction coefficient of the materials and to establish the type of failures that would result when loading beyond the limit. It was found that in general a simple constant rolling traction coefficient was enough to describe the results of all the test. The slip traction tests revealed that the peak traction coefficients were considerably higher than for lubricated traction contacts. The endurance traction tests were performed to establish the durability of the LMM under conditions of prolonged traction. Wear measurements were performed during and after the test. Energetic wear rates were determined from the wear measurements conducted in the endurance traction tests. These values show that the roller wear is not severe when reasonable levels of traction are transmitted.
Two-stage bulk electron heating in the diffusion region of anti-parallel symmetric reconnection
NASA Astrophysics Data System (ADS)
Le, A.; Egedal, J.; Daughton, W.
2016-10-01
Electron bulk energization in the diffusion region during anti-parallel symmetric reconnection entails two stages. First, the inflowing electrons are adiabatically trapped and energized by an ambipolar parallel electric field. Next, the electrons gain energy from the reconnection electric field as they undergo meandering motion. These collisionless mechanisms have been described previously, and they lead to highly structured electron velocity distributions. Nevertheless, a simplified control-volume analysis gives estimates for how the net effective heating scales with the upstream plasma conditions in agreement with fully kinetic simulations and spacecraft observations.
Silicon Bulk Micromachined Vibratory Gyroscope
NASA Technical Reports Server (NTRS)
Tang, T. K.; Gutierrez, R. C.; Wilcox, J. Z.; Stell, C.; Vorperian, V.; Calvet, R.; Li, W. J.; Charkaborty, I.; Bartman, R.; Kaiser, W. J.
1996-01-01
This paper reports on design, modeling, fabrication, and characterization of a novel silicon bulk micromachined vibratory rate gyroscope designed for microspacecraft applications. The new microgyroscope consists of a silicon four leaf cloverstructure with a post attached to the center.
Possible contribution of low shear modulus C₄₄ to the low Young’s modulus of Ti-36Nb-5Zr alloy
Meng, Qingkun; Guo, Shun; Ren, Xiaobing; Xu, Huibin; Zhao, Xinqing
2014-09-29
Despite the importance of single-crystal elastic constants of β-phase titanium alloys in understanding their low Young's modulus—a property crucial for many applications, such data are often difficult to obtain when the alloy composition is close to the instability limit of the β phase, where the presence of α" martensite precludes the fabrication of β-phase single crystal. In the present study, we extracted the single-crystal elastic constants of such a β-phase titanium alloy with low Young's modulus, Ti-36Nb-5Zr (wt. %), from polycrystalline specimens by using an in-situ synchrotron X-ray diffraction technique. It is indicated that the low Young's modulus of the alloy originates from the anomalously low shear modulus C₄₄ as well as the low shear modulus C', which is different from a common viewpoint that the Young's modulus of β-phase titanium alloys is dominantly controlled by the C'. This suggests that low C₄₄ is an important contributor to low Young's modulus for instable β-phase titanium alloys.
Possible contribution of low shear modulus C{sub 44} to the low Young's modulus of Ti-36Nb-5Zr alloy
Meng, Qingkun; Xu, Huibin; Zhao, Xinqing; Guo, Shun; Ren, Xiaobing
2014-09-29
Despite the importance of single-crystal elastic constants of β-phase titanium alloys in understanding their low Young's modulus—a property crucial for many applications, such data are often difficult to obtain when the alloy composition is close to the instability limit of the β phase, where the presence of α' martensite precludes the fabrication of β-phase single crystal. In the present study, we extracted the single-crystal elastic constants of such a β-phase titanium alloy with low Young's modulus, Ti-36Nb-5Zr (wt. %), from polycrystalline specimens by using an in-situ synchrotron X-ray diffraction technique. It is indicated that the low Young's modulus of the alloy originates from the anomalously low shear modulus C{sub 44} as well as the low shear modulus C′, which is different from a common viewpoint that the Young's modulus of β-phase titanium alloys is dominantly controlled by the C′. This suggests that low C{sub 44} is an important contributor to low Young's modulus for instable β-phase titanium alloys.
Bulk pesticide storage - state perspective
Buzicky, G.
1994-12-31
State bulk pesticide storage regulations continue to evolve differentially due, in large part, to the absence of federal regulations. This is about to change because of the pending promulgation of 40 CFR Part 165, as amended in 1988 by the Environmental Protection Agency (EPA) rules regarding storage, handling and disposal. Until final adoption of the rules by EPA, states continue to address bulk pesticide storage and handling according to individual state statute, rules and guidelines.
Experimentally-based relaxation modulus of polyurea and its composites
NASA Astrophysics Data System (ADS)
Jia, Zhanzhan; Amirkhizi, Alireza V.; Nantasetphong, Wiroj; Nemat-Nasser, Sia
2016-06-01
Polyurea is a block copolymer that has been widely used in the coating industry as an abrasion-resistant and energy-dissipative material. Its mechanical properties can be tuned by choosing different variations of diamines and diisocyanates as well as by adding various nano- and micro-inclusions to create polyurea-based composites. Our aim here is to provide the necessary experimentally-based viscoelastic constitutive relations for polyurea and its composites in a format convenient to support computational studies. The polyurea used in this research is synthesized by the reaction of Versalink P-1000 (Air Products) and Isonate 143L (Dow Chemicals). Samples of pure polyurea and polyurea composites are fabricated and then characterized using dynamic mechanical analysis (DMA). Based on the DMA data, master curves of storage and loss moduli are developed using time-temperature superposition. The quality of the master curves is carefully assessed by comparing with the ultrasonic wave measurements and by Kramers-Kronig relations. Based on the master curves, continuous relaxation spectra are calculated, then the time-domain relaxation moduli are approximated from the relaxation spectra. Prony series of desired number of terms for the frequency ranges of interest are extracted from the relaxation modulus. This method for developing cost efficient Prony series has been proven to be effective and efficient for numerous DMA test results of many polyurea/polyurea-based material systems, including pure polyurea with various stoichiometric ratios, polyurea with milled glass inclusions, polyurea with hybrid nano-particles and polyurea with phenolic microbubbles. The resulting viscoelastic models are customized for the frequency ranges of interest, reference temperature and desired number of Prony terms, achieving both computational accuracy and low cost. The method is not limited to polyurea-based systems. It can be applied to other similar polymers systems.
The effect of elastic modulus on ablation catheter contact area
NASA Astrophysics Data System (ADS)
Camp, Jon J.; Linte, Cristian A.; Rettmann, Maryam E.; Sun, Deyu; Packer, Douglas L.; Robb, Richard A.; Holmes, David R.
2015-03-01
Cardiac ablation consists of navigating a catheter into the heart and delivering RF energy to electrically isolate tissue regions that generate or propagate arrhythmia. Besides the challenges of accurate and precise targeting of the arrhythmic sites within the beating heart, limited information is currently available to the cardiologist regarding intricate electrodetissue contact, which directly impacts the quality of produced lesions. Recent advances in ablation catheter design provide intra-procedural estimates of tissue-catheter contact force, but the most direct indicator of lesion quality for any particular energy level and duration is the tissue-catheter contact area, and that is a function of not only force, but catheter pose and material elasticity as well. In this experiment, we have employed real-time ultrasound (US) imaging to determine the complete interaction between the ablation electrode and tissue to accurately estimate contact, which will help to better understand the effect of catheter pose and position relative to the tissue. By simultaneously recording tracked position, force reading and US image of the ablation catheter, the differing material properties of polyvinyl alcohol cryogel[1] phantoms are shown to produce varying amounts of tissue depression and contact area (implying varying lesion quality) for equivalent force readings. We have shown that the elastic modulus significantly affects the surface-contact area between the catheter and tissue at any level of contact force. Thus we provide evidence that a prescribed level of catheter force may not always provide sufficient contact area to produce an effective ablation lesion in the prescribed ablation time.
Estimation of the Young’s modulus of cellulose Iß by MM3 and quantum mechanics
Technology Transfer Automated Retrieval System (TEKTRAN)
Young’s modulus provides a measure of the resistance to deformation of an elastic material. In this study, modulus estimations for models of cellulose Iß relied on calculations performed with molecular mechanics (MM) and quantum mechanics (QM) programs. MM computations used the second generation emp...
Adiabat shape Laser Pulses for ablation front instability control and high fuel compression
NASA Astrophysics Data System (ADS)
Milovich, Jose; Jones, O. S.; Berzak-Hopkins, L.; Clark, D. S.; Baker, K. L.; Casey, D. T.; Macphee, A. G.; Peterson, J. L.; Robey, H. F.; Smalyuk, V. A.; Weber, C. R.
2014-10-01
At the end of the NIC campaign a large body of experimental evidence showed that the point-design implosions driven by low-adiabat pulses had a high degree of mix. To reduce instability a high-adiabat (~3 × higher picket drive) design was fielded in the National Ignition Facility (NIF). The experimental results from this campaign have shown considerable improvement in performance (10 × neutron yields) over the point design with little evidence of mix. However, the adiabat of the implosions may be too high to achieve ignition for the available laser energy. To overcome this difficulty, and to take advantage of the high-picket drives, we have developed hybrid laser pulses that combined the virtue of both designs. These pulses can be thought of achieving adiabat shaping, where the ablator is set in a higher adiabat for instability control, while the fuel is maintained at a lower adiabat favoring higher fuel compression. Using these pulses, recent experiments at the NIF have indeed shown reduced growth rates. In this talk we will present the design of high-yield low-growth DT ignition experiments using these adiabat-shaped pulses. Work performed under the auspices of the U.S. D.O.E. by LLNL under contract DE-AC52-07NA27344.
NASA Astrophysics Data System (ADS)
Song, Chuan-Jing; Zhang, Yi
2015-08-01
For El-Nabulsi's fractional Birkhoff system, Mei symmetry perturbation, the corresponding Mei-type adiabatic invariants and Noether-type adiabatic invariants are investigated in this paper. Firstly, based on El-Nabulsi-Birkhoff fractional equations, Mei symmetry and the corresponding Mei conserved quantity, Noether conserved quantity deduced indirectly by Mei symmetry are studied. Secondly, Mei-type exact invariants and Noether-type exact invariants are given on the basis of the definition of adiabatic invatiant. Thirdly, Mei symmetry perturbation, Mei-type adiabatic invariants and Noether-type adiabatic invariants for the disturbed El-Nabulsi's fractional Birkhoff system are studied. Finally, two examples, Hojman-Urrutia problem for Mei-type adiabatic invariants and another for the Noether-type adiabatic invariants, are given to illustrate the application of the results. Supported by the National Natural Science Foundation of China under Grant Nos. 10972151 and 11272227, and the Innovation Program for Scientific Research of Nanjing University of Science and Technology
Energy-Efficient and Secure S-Box circuit using Symmetric Pass Gate Adiabatic Logic
Kumar, Dinesh; Mohammad, Azhar; Singh, Vijay; Perumalla, Kalyan S
2016-01-01
Differential Power Analysis (DPA) attack is considered to be a main threat while designing cryptographic processors. In cryptographic algorithms like DES and AES, S-Box is used to indeterminate the relationship between the keys and the cipher texts. However, S-box is prone to DPA attack due to its high power consumption. In this paper, we are implementing an energy-efficient 8-bit S-Box circuit using our proposed Symmetric Pass Gate Adiabatic Logic (SPGAL). SPGAL is energy-efficient as compared to the existing DPAresistant adiabatic and non-adiabatic logic families. SPGAL is energy-efficient due to reduction of non-adiabatic loss during the evaluate phase of the outputs. Further, the S-Box circuit implemented using SPGAL is resistant to DPA attacks. The results are verified through SPICE simulations in 180nm technology. SPICE simulations show that the SPGAL based S-Box circuit saves upto 92% and 67% of energy as compared to the conventional CMOS and Secured Quasi-Adiabatic Logic (SQAL) based S-Box circuit. From the simulation results, it is evident that the SPGAL based circuits are energy-efficient as compared to the existing DPAresistant adiabatic and non-adiabatic logic families. In nutshell, SPGAL based gates can be used to build secure hardware for lowpower portable electronic devices and Internet-of-Things (IoT) based electronic devices.
Recent developments in trapping and manipulation of atoms with adiabatic potentials
NASA Astrophysics Data System (ADS)
Garraway, Barry M.; Perrin, Hélène
2016-09-01
A combination of static and oscillating magnetic fields can be used to ‘dress’ atoms with radio-frequency (RF), or microwave, radiation. The spatial variation of these fields can be used to create an enormous variety of traps for ultra-cold atoms and quantum gases. This article reviews the type and character of these adiabatic traps and the applications which include atom interferometry and the study of low-dimensional quantum systems. We introduce the main concepts of magnetic traps leading to adiabatic dressed traps. The concept of adiabaticity is discussed in the context of the Landau-Zener model. The first bubble trap experiment is reviewed together with the method used for loading it. Experiments based on atom chips show the production of double wells and ring traps. Dressed atom traps can be evaporatively cooled with an additional RF field, and a weak RF field can be used to probe the spectroscopy of the adiabatic potentials. Several approaches to ring traps formed from adiabatic potentials are discussed, including those based on atom chips, time-averaged adiabatic potentials and induction methods. Several proposals for adiabatic lattices with dressed atoms are also reviewed.
Modelling of bulk superconductor magnetization
NASA Astrophysics Data System (ADS)
Ainslie, M. D.; Fujishiro, H.
2015-05-01
This paper presents a topical review of the current state of the art in modelling the magnetization of bulk superconductors, including both (RE)BCO (where RE = rare earth or Y) and MgB2 materials. Such modelling is a powerful tool to understand the physical mechanisms of their magnetization, to assist in interpretation of experimental results, and to predict the performance of practical bulk superconductor-based devices, which is particularly important as many superconducting applications head towards the commercialization stage of their development in the coming years. In addition to the analytical and numerical techniques currently used by researchers for modelling such materials, the commonly used practical techniques to magnetize bulk superconductors are summarized with a particular focus on pulsed field magnetization (PFM), which is promising as a compact, mobile and relatively inexpensive magnetizing technique. A number of numerical models developed to analyse the issues related to PFM and optimise the technique are described in detail, including understanding the dynamics of the magnetic flux penetration and the influence of material inhomogeneities, thermal properties, pulse duration, magnitude and shape, and the shape of the magnetization coil(s). The effect of externally applied magnetic fields in different configurations on the attenuation of the trapped field is also discussed. A number of novel and hybrid bulk superconductor structures are described, including improved thermal conductivity structures and ferromagnet-superconductor structures, which have been designed to overcome some of the issues related to bulk superconductors and their magnetization and enhance the intrinsic properties of bulk superconductors acting as trapped field magnets. Finally, the use of hollow bulk cylinders/tubes for shielding is analysed.
E-modulus evolution and its relation to solids formation of pastes from commercial cements
Maia, Lino; Azenha, Miguel; Geiker, Mette; Figueiras, Joaquim
2012-07-15
Models for early age E-modulus evolution of cement pastes are available in the literature, but their validation is limited. This paper provides correlated measurements of early age evolution of E-modulus and hydration of pastes from five commercial cements differing in limestone content. A recently developed methodology allowed continuous monitoring of E-modulus from the time of casting. The methodology is a variant of classic resonant frequency methods, which are based on determination of the first resonant frequency of a composite beam containing the material. The hydration kinetics - and thus the rate of formation of solids - was determined using chemical shrinkage measurements. For the cements studied similar relationships between E-modulus and chemical shrinkage were observed for comparable water-to-binder ratio. For commercial cements it is suggested to model the E-modulus evolution based on the amount of binder reacted, instead of the degree of hydration.
Indentation-derived elastic modulus of multilayer thin films: Effect of unloading induced plasticity
Jamison, Ryan Dale; Shen, Yu -Lin
2015-08-13
Nanoindentation is useful for evaluating the mechanical properties, such as elastic modulus, of multilayer thin film materials. A fundamental assumption in the derivation of the elastic modulus from nanoindentation is that the unloading process is purely elastic. In this work, the validity of elastic assumption as it applies to multilayer thin films is studied using the finite element method. The elastic modulus and hardness from the model system are compared to experimental results to show validity of the model. Plastic strain is shown to increase in the multilayer system during the unloading process. Additionally, the indentation-derived modulus of a monolayer material shows no dependence on unloading plasticity while the modulus of the multilayer system is dependent on unloading-induced plasticity. Lastly, the cyclic behavior of the multilayer thin film is studied in relation to the influence of unloading-induced plasticity. Furthermore, it is found that several cycles are required to minimize unloading-induced plasticity.