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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 1373-1382 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Deuterium nuclear magnetic resonance (2H-NMR) was performed on the rigid perdeuterated fluorene segment of the compound 2-fluorenyl-4'-tetradecyloxy benzoate (FLOC 14-d9) to unambiguously measure the order parameter U which reflects the degree of asymmetric ordering of the molecule in the nematic liquid crystalline phase. Measurements of U showed this parameter to be finite at all temperatures in the nematic phase indicative of the uniaxial phase U2 described in the Allender–Lee generalized Landau theory. Mixtures of FLOC 14-d9 with compounds consisting of molecules more cylindrical in shape were also studied to examine their effect on the parameter U. Other parameters such as the degree of order S and the orientation of the principal axes of the Maier–Saupe order matrix were measured and are discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 35 (1994), S. 1622-1633 
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: Second harmonic generation, an important phenomenon in nonlinear optics, is modeled in this work. The model is derived from a nonlinear system of Maxwell's equations, which overcomes the known shortcomings of some commonly used models in the literature. Existence and uniqueness of solutions are established by a combination of a variational approach and the contraction mapping principle. Some numerical results are also presented.
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 3925-3931 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The refractive index of the polymer np is adjusted relative to the ordinary refractive index of dispersed droplets of nematic liquid crystal no to regulate the angle of maximum transmission through a film in the presence of an applied field. Maximum transmission occurs at normal incidence when np≤no with the breadth of the angle of view being largest at np=no. When np〉no, maximum transmission is peaked at an angle away from normal incidence, the value of the angle depending upon the ratio np/no. Angular discriminating filters are therefore possible with these films. The optical response of these materials as a function of applied field is also shown to be dependent on the ratio np/no as is the contrast exhibited by information displays. Methods for measuring the scattering cross section of a nematic droplet are also described.
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  • 4
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Biomedical Engineering 2 (2000), S. 189-226 
    ISSN: 1523-9829
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Technology , Medicine
    Notes: Abstract As the basic unit of life, the cell is a biologically complex system, the understanding of which requires a combination of various approaches including biomechanics. With recent progress in cell and molecular biology, the field of cell mechanics has grown rapidly over the last few years. This review synthesizes some of these recent developments to foster new concepts and approaches, and it emphasizes molecular-level understanding. The focuses are on the common themes and interconnections in three related areas: (a) the responses of cells to mechanical forces, (b) the mechanics and kinetics of cell adhesion, and (c) the deformation of biomolecules. Specific examples are also given to illustrate the quantitative modeling used in analyzing biological processes and physiological functions.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 392-394 (Oct. 2008), p. 116-120 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In order to predict the dynamic characteristics, the piezoelectric valve-less diffusermicropump is equivalent to the hydraulic model which consists of several hydraulic components.Using finite element analysis (FEA) method, the static analysis and the natural frequency calculationof the diaphragm are carried out. The mathematical model and the simulation method using AMESimare developed. Simulation results show the pressure and flow rate characteristics of the micropump,as well as the diaphragm stiffness influence. The agreement between the simulation results and thosepublished previously indicates that the method combining FEA with the hydraulic analogue modelprovides a relatively simple and effective tool to study the dynamic characteristics of micropumps
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  • 6
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 399 (1999), S. 564-566 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Polymer dynamics are of central importance in materials science, mechanical engineering, biology and medicine,. The dynamics of macromolecular solutions and melts in shear flow are typically studied using bulk experimental methods such as light and neutron scattering and birefringence,. But the ...
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  • 7
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 575-578 (Apr. 2008), p. 1228-1233 
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Being as a functional material, piezoelectric ceramics is applied to drive a micropumpwhen it is composed to be a thin membrane on a brass film to form a diaphragm. According to theproperties of the piezoelectric material, the stiffness of the diaphragm influences the vibrationdisplacement and therefore the supply flow rate of the micropump. This paper focuses on thedynamic characteristic study of the micropump and the stiffness influence of the diaphragm on thecharacteristics. The mathematical model of the valve-less micropump considering the diaphragmstiffness is developed in order to predict the dynamic characteristics of the piezoelectric valve-lessmicropump. Using the 3-D finite element analysis (FEA) method, the static and vibration mode ofthe diaphragm are analyzed to obtain the diaphragm stiffness and natural frequency. The methodusing Matlab is to predict the pressure and flow rate characteristics of the micropump when thediaphragm stiffness is considered or not. Comparison of the simulation results shows the stiffness ofthe diaphragm influences the dynamic characteristics of micropumps. It also shows that the methodcombining FEA software with Matlab provides a possible and effective tool to take the diaphragmstiffness into account when the pressure and flow rate characteristics of micropumps are studied
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Numerische Mathematik 75 (1996), S. 1-16 
    ISSN: 0945-3245
    Keywords: Mathematics Subject Classification (1991):78A45, 65N30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary. The diffraction of a time harmonic wave in TM polarization by some periodic inhomogeneous material is studied in this paper. The diffraction problem is modeled by a generalized Helmholtz equation with transparent boundary conditions. Existence and uniqueness are proved for the model problem. Uniform error estimates for the finite element approximation of the solution are established. Error estimates are also obtained when the truncation of the nonlocal boundary operators takes place.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Wireless networks 2 (1996), S. 229-237 
    ISSN: 1572-8196
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Computer Science
    Notes: Abstract Due to the high frame error rate in wireless communication channels, an additional link layer protocol, Radio Link Protocol (RLP), has been introduced in the newly approvedData Services Option Standard for Wideband Spread Spectrum Digital Cellular System. In this paper, we investigate performance issues of a typical Cod Division Multiple Access (CDMA) wireless link using the protocol stack given in the standard. In particular, we focus on the dynamics of the TCP and RLP layers of the protocol stack since the fluctuation of system performance is largely caused by Automatic Repeat Request (ARQ) mechanisms implemented at these two layers. We compare the network performance of default parameter setting to those of other possible parameter settings. Analytical and simulation results presented in this paper can provide guidance to those attempting to further improve performance of interest.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Archive for rational mechanics and analysis 132 (1995), S. 49-72 
    ISSN: 1432-0673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract Suppose the 3-dimensional space is filled with three materials having dielectric constants ɛ 1 above S 1={x 2=f 1(x 1), x 3 arbitrary}, ɛ 2 below S 2 = {x 2 =f 2(x 1), x 3 arbitrary} and ɛ o in {f 2(x 1) 〈x 2 〈f1(x 1), x 3 arbitrary} where f 1 f 2 are periodic functions. Suppose for a plane wave incident on S 1 from above we can measure the reflected and transmitted waves of the corresponding time-harmonic solution of the Maxwell equations, say at x 2=±b,b large. To what extent can we infer from these measurements the location of the pair (S 1, S 2 ? In this paper, we establish a local stability: If ( $$\tilde S_1 ,\tilde S_2$$ ) is another pair of periodic curves “close” to (S 1, S2), then, for any δ〉0, if the measurements for the two pairs are δ-close, then $$\tilde S_1$$ and $$\tilde S_2$$ are 0(δ)-close to S 1 and S 2, respectively.
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